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Sample records for platinum ii porphyrin

  1. Determination of quercetin using a photo-electrochemical sensor modified with titanium dioxide and a platinum(II)-porphyrin complex

    International Nuclear Information System (INIS)

    Tian, Li; Wang, Binbin; Chen, Ruizhan; Gao, Ye; Chen, Yanling; Li, Tianjiao

    2015-01-01

    A glassy carbon electrode (GCE) was modified with a film containing titanium dioxide and a Pt(II)-porphyrin complex, and its response to quercetin was investigated employing cyclic voltammetry and chronoamperometry. The oxidation current caused by quercetin is largely enhanced under UV illumination. The effects of pH value, mass of TiO 2 in the film, UV illumination time and applied potential were studied. Under optimized conditions, the peak current at a typically applied voltage of +0.4 V depends linearly on the concentration of quercetin in the 0.002 to 50 mg L −1 range. The detection limit (at an SNR of 3) is 0.8 μg L −1 . The method was successfully applied to the determination of quercetin in (spiked) samples of tea and apple juice. (author)

  2. Platinum porphyrins as ionophores in polymeric membrane electrodes

    DEFF Research Database (Denmark)

    Lvova, Larisa; Verrelli, Giorgio; Nardis, Sara

    2011-01-01

    A comparative study of Pt(II)- and Pt(IV)-porphyrins as novel ionophores for anion-selective polymeric membrane electrodes is performed. Polymeric membranes of different compositions, prepared by varying plasticizers, cationic and anionic additives and Pt porphyrins, have been examined...... within the electrode membranes, while those based on Pt(IV)TPPCl2 operate via a mixed mode carrier mechanism, evidencing also a partial reduction of the starting ionophore to Pt(II)TPP. Spectrophotometric measurements of thin polymeric films indicate that no spontaneous formation of hydroxide ion bridged...... porphyrin dimers occurs in the membrane plasticized both with high or low dielectric constant plasticizer, due to a low oxophilicity of central Pt. The computational study of various anion–Pt(IV)TPPCl2 complex formation by means of semi-empirical and density functional theory (DFT) methods revealed a good...

  3. Pt(II) porphyrin modified TiO{sub 2} composites as photocatalysts for efficient 4-NP degradation

    Energy Technology Data Exchange (ETDEWEB)

    Mingyue, Duan [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xian, Shaanxi 710069 (China); Li Jun, E-mail: junli@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xian, Shaanxi 710069 (China); Min, Li [Datang Wujiang Gas Turbine Power Limited Liability Company, Jiangsu 215214 (China); Zengqi, Zhang; Chen, Wang [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xian, Shaanxi 710069 (China)

    2012-05-01

    Three Pt(II) porphyrins 5,10,15,20-tetra-[2 or 3 or 4-(3-phenoxy)propoxy]phenyl porphyrin]platinum(II) (1-3) were synthesized and characterized spectroscopically. The corresponding Pt(II) porphyrins-TiO{sub 2} composites were then prepared and characterized by means of FT-IR and diffused reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of Pt(II) porphyrins-TiO{sub 2} catalyst was investigated by testing the photodegradation of 4-nitrophenol (4-NP) in aqueous solution under irradiation with Xenon lamp. The results indicated that Pt(II) porphyrins greatly enhanced the photocatalytic efficiency of bare TiO{sub 2} in photodegrading the 4-NP, and the distinct space tropisms of peripheral substituents in meso-sites of porphyrin ring led to different results.

  4. Nanostructured oxygen sensor--using micelles to incorporate a hydrophobic platinum porphyrin.

    Directory of Open Access Journals (Sweden)

    Fengyu Su

    Full Text Available Hydrophobic platinum(II-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl-porphyrin (PtTFPP was physically incorporated into micelles formed from poly(ε-caprolactone-block-poly(ethylene glycol to enable the application of PtTFPP in aqueous solution. Micelles were characterized using dynamic light scattering (DLS and atomic force microscopy (AFM to show an average diameter of about 140 nm. PtTFPP showed higher quantum efficiency in micellar solution than in tetrahydrofuran (THF and dichloromethane (CH₂Cl₂. PtTFPP in micelles also exhibited higher photostability than that of PtTFPP suspended in water. PtTFPP in micelles exhibited good oxygen sensitivity and response time. This study provided an efficient approach to enable the application of hydrophobic oxygen sensors in a biological environment.

  5. Porphyrins

    Science.gov (United States)

    Gotelli, George R.; Wall, Jeffrey H.; Kabra, Pokar M.; Marton, Laurence J.

    Historically the term porphyria has been used since it was coined in 1871 to describe a purple colored material extracted from pathological feces (1). The first case of porphyria was reported in 1874, (2, 3), but until the 1930 Nobel Prize winning work of Hans Fischer on the synthesis of protoporphyrin, there was little more than academic interest in porphyrin analysis. During the forty years between 1930 and 1970, the biosynthetic pathways leading to the formation of heme, and the details of porphyrin metabolism, were elucidated. During this time quantitative methods for porphyrins in biological fluids used complex and laborious solvent extraction techniques, requiring large sample volumes and hours to complete. We now know that these methods only partially separated the complex mixture of porphyrins found in biological fluids. These solvent extraction procedures fractionated the porphyrins into two broad groups, uroporphyrins (octacarboxylic) and coproporphyrins (tetracarboxylic). However, intermediate carboxylated porphyrin containing 2, 3, 5, 6, and 7 carboxyl groups are now known to exist in normal and pathlogical excreta, which were not differentiated, but which were included in the two broad uroporphyrin and copropophyrin groups.

  6. Substituted group and side chain effects for the porphyrin and zinc(II)–porphyrin derivatives: A DFT and TD-DFT study

    International Nuclear Information System (INIS)

    Tai, Chin-Kuen; Chuang, Wen-Hua; Wang, Bo-Cheng

    2013-01-01

    The DFT/B3LYP/LANL2DZ and TD-DFT calculations have been performed to generate the optimized structures, electronic and photo-physical properties for the porphyrin and zinc(II)–porphyrin (metalloporphyrin) derivatives. The substituted group and side chain effects for these derivatives are discussed in this study. According to the calculation results, the side chain moiety extends the π-delocalization length from the porphyrin core to the side chain moiety. The substituted group with a stronger electron-donating ability increases the energy level of highest occupied molecular orbital (E HOMO ). The side chain moiety with a lower resonance energy decreases E HOMO , the energy level of the lowest unoccupied molecular orbital (E LUMO ), and the energy gap (E g ) between HOMO and LUMO in the porphyrin and zinc(II)–porphyrin derivatives. The natural bonding orbital (NBO) analysis determines the possible electron transfer mechanism from the electron-donating to -withdrawing groups (the side chain moiety) in these porphyrin derivatives. The projected density of state (PDOS) analysis shows that the electron-donating group affects the electron density distribution in both HOMO and LUMO, and the side chain moiety influence the electron density distribution in LUMO. The calculated photo-physical properties (absorption wavelengths and the related oscillator strength, f) in dichloromethane environment for porphyrin and zinc(II)–porphyrin derivatives have been simulated by using the TD-DFT method within the Polarizable Continuum Model (PCM). The present of both of the substituted group and the side chain moiety in these derivatives results in a red shift and broadening of the range of the absorption peaks of the Q/Soret band as compared to porphin. -- Highlights: • Side chain moiety extends the π-delocalization for the porphyrins. • Substituted group increases the energy of highest occupied molecular orbital. • Side chain moiety influences the Q/Soret band of

  7. Highly red-shifted NIR emission from a novel anthracene conjugated polymer backbone containing Pt( ii ) porphyrins

    KAUST Repository

    Freeman, D. M. E.

    2015-11-30

    © The Royal Society of Chemistry 2016. We present the synthesis of a novel diphenylanthracene (DPA) based semiconducting polymer. The polymer is solubilised by alkoxy groups attached directly to a DPA monomer, meaning the choice of co-monomer is not limited to exclusively highly solubilising moieties. Interestingly, the polymer shows a red-shifted elecroluminescence maximum (510 nm) when compared to its photoluminescence maximum (450 nm) which we attribute to excimer formation. The novel polymer was utilised as a host for a covalently-linked platinum(ii) complexed porphyrin dopant. Emission from these polymers was observed in the NIR and again showed almost a 100 nm red shift from photoluminescence to electroluminescence. This work demonstrates that utilising highly aggregating host materials is an effective tool for inducing red-shifted emission in OLEDs.

  8. Iron(II) porphyrins induced conversion of nitrite into nitric oxide: A computational study.

    Science.gov (United States)

    Zhang, Ting Ting; Liu, Yong Dong; Zhong, Ru Gang

    2015-09-01

    Nitrite reduction to nitric oxide by heme proteins was reported as a protective mechanism to hypoxic injury in mammalian physiology. In this study, the pathways of nitrite reduction to nitric oxide mediated by iron(II) porphyrin (P) complexes, which were generally recognized as models for heme proteins, were investigated by using density functional theory (DFT). In view of two type isomers of combination of nitrite and Fe(II)(P), N-nitro- and O-nitrito-Fe(II)-porphyrin complexes, and two binding sites of proton to the different O atoms of nitrite moiety, four main pathways for the conversion of nitrite into nitric oxide mediated by iron(II) porphyrins were proposed. The results indicate that the pathway of N-bound Fe(II)(P)(NO2) isomer into Fe(III)(P)(NO) and water is similar to that of O-bound isomer into nitric oxide and Fe(III)(P)(OH) in both thermodynamical and dynamical aspects. Based on the initial computational studies of five-coordinate nitrite complexes, the conversion of nitrite into NO mediated by Fe(II)(P)(L) complexes with 14 kinds of proximal ligands was also investigated. Generally, the same conclusion that the pathways of N-bound isomers are similar to those of O-bound isomer was obtained for iron(II) porphyrin with ligands. Different effects of ligands on the reduction reactions were also found. It is notable that the negative proximal ligands can improve reactive abilities of N-nitro-iron(II) porphyrins in the conversion of nitrite into nitric oxide compared to neutral ligands. The findings will be helpful to expand our understanding of the mechanism of nitrite reduction to nitric oxide by iron(II) porphyrins. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Excitation energy transfer in ruthenium (II)-porphyrin conjugates led to enhanced emission quantum yield and 1O2 generation

    International Nuclear Information System (INIS)

    Pan, Jie; Jiang, Lijun; Chan, Chi-Fai; Tsoi, Tik-Hung; Shiu, Kwok-Keung; Kwong, Daniel W.J.; Wong, Wing-Tak; Wong, Wai-Kwok; Wong, Ka-Leung

    2017-01-01

    Porphyrins are good photodynamic therapy (PDT) agents due to its flexibility for modifications to achieve tumor localization and photo-cytotoxicity against cancer. Yet they are not perfect. In a Ru(polypyridyl)-porphyrin system, the Ru(polypyridyl) moiety improves the water solubility and cell permeability. Consider the similar excited state energies between Ru(polypyridyl) and porphyrin moieties; a small perturbation (e.g. Zn(II) metalation) would lead to a marked change in the energy migration process. In this work, we have synthesized a series of porphyrins conjugated with Ru(polypyridyl) complexes using different linkers and investigated their photophysical properties, which included singlet oxygen quantum yield and their in vitro biological properties, resulting from linker variation and porphyrin modification by Zn(II) metalation. - Graphical abstract: Four amphiphilic ruthenium(II)-porphyrin complexes were prepared that display energy transfer conversion with zinc coordination, lysosome specific target, low dark toxicity and efficient photodynamic therapy.

  10. Photoinduced triplet-state electron transfer of platinum porphyrin: a one-step direct method for sensing iodide with an unprecedented detection limit

    KAUST Repository

    Masih, Dilshad

    2015-02-05

    Here, we report for the first time a one-step direct method for sensing halides in aqueous solution using phosphorescence quenching of platinum-cationic porphyrin. This method offers an easy, rapid, environmentally friendly, ultra-sensitive (with a previously unattained detection limit of 1 × 10−12 M) and economical method for the determination of iodide. To fully understand the reaction mechanism responsible for the phosphorescence quenching process, we have employed cutting-edge time-resolved laser spectroscopy with broadband capabilities.

  11. Platinum(II) complexes as spectroscopic probes for biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Ratilla, E.

    1990-09-21

    The use of platinum(II) complexes as tags and probes for biomolecules is indeed advantageous for their reactivities can be selective for certain purposes through an interplay of mild reaction conditions and of the ligands bound to the platinum. The use of {sup 195}Pt NMR as a method of detecting platinum and its interactions with biomolecules was carried out with the simplest model of platinum(II) tagging to proteins. Variable-temperature {sup 195}Pt NMR spectroscopy proved useful in studying the stereodynamics of complex thioethers like methionine. The complex, Pt(trpy)Cl{sup +}, with its chromophore has a greater potential for probing proteins. It is a noninvasive and selective tag for histidine and cysteine residues on the surface of cytochrome c at pH 5. The protein derivatives obtained are separable, and the tags are easily quantitated and differentiated through the metal-to-ligand charge transfer bands which are sensitive to the environment of the tag. Increasing the pH to 7.0 led to the modification by Pt(trpy)Cl{sup +}of Arg 91 in cytochrome c. Further studies with guanidine-containing ligands as models for arginine modification by Pt(trpy)Cl{sup +} showed that guanidine can act as a terminal ligand and as a bridging ligand. Owing to the potential utility of Pt(trpy)L{sup n+} as electron dense probes of nucleic acid structure, interactions of this bis-Pt(trpy){sup 2+} complex with nucleic acids was evaluated. Indeed, the complex interacts non-covalently with nucleic acids. Its interactions with DNA are not exactly the same as those of its precedents. Most striking is its ability to form highly immobile bands of DNA upon gel electrophoresis. 232 refs.

  12. Building-up novel coordination polymer with Zn(II) porphyrin dimer ...

    Indian Academy of Sciences (India)

    mer with porphyrin dimer. Solution structures of the complexes along with binding studies in solution between ... porphyrin polymers by self-assembly is fascinating ..... ture determination. ..... J K M 2000 In The Porphyrin Handbook Kadish K M,.

  13. Excitation energy transfer in ruthenium (II)-porphyrin conjugates led to enhanced emission quantum yield and {sup 1}O{sub 2} generation

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Jie; Jiang, Lijun; Chan, Chi-Fai [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Tsoi, Tik-Hung [Department of Applied Biology and Chemical Technology, Hung Hom, Hong Kong Special Administrative Region (Hong Kong); Shiu, Kwok-Keung; Kwong, Daniel W.J. [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Wong, Wing-Tak [Department of Applied Biology and Chemical Technology, Hung Hom, Hong Kong Special Administrative Region (Hong Kong); Wong, Wai-Kwok, E-mail: wkwong@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong); Wong, Ka-Leung, E-mail: klwong@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region (Hong Kong)

    2017-04-15

    Porphyrins are good photodynamic therapy (PDT) agents due to its flexibility for modifications to achieve tumor localization and photo-cytotoxicity against cancer. Yet they are not perfect. In a Ru(polypyridyl)-porphyrin system, the Ru(polypyridyl) moiety improves the water solubility and cell permeability. Consider the similar excited state energies between Ru(polypyridyl) and porphyrin moieties; a small perturbation (e.g. Zn(II) metalation) would lead to a marked change in the energy migration process. In this work, we have synthesized a series of porphyrins conjugated with Ru(polypyridyl) complexes using different linkers and investigated their photophysical properties, which included singlet oxygen quantum yield and their in vitro biological properties, resulting from linker variation and porphyrin modification by Zn(II) metalation. - Graphical abstract: Four amphiphilic ruthenium(II)-porphyrin complexes were prepared that display energy transfer conversion with zinc coordination, lysosome specific target, low dark toxicity and efficient photodynamic therapy.

  14. The Chameleonic Nature of Platinum(II) Imidazopyridine Complexes.

    Science.gov (United States)

    Pinter, Piermaria; Pittkowski, Rebecca; Soellner, Johannes; Strassner, Thomas

    2017-10-12

    The synthesis and characterization of cyclometalated C^C* platinum(II) complexes with unique photophysical properties, aggregation induced enhancement of the quantum yields with a simultaneous decrease of phosphorescence lifetimes, is reported. Additionally, a change of emission color is induced by variation of the excitation wavelength. The aggregation behavior of these complexes is controlled by the steric demand of the substituents. The photophysical properties of these complexes are investigated through emission-excitation matrix analysis (EEM). The monomeric complexes are excellent room temperature phosphorescent blue emitters with emission maxima below 470 nm and quantum yields of up to 93 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Solvent effects on the fluorescence and effective three-photon absorption of a Zn(II)-[meso-tetrakis(4-octyloxyphenyl)porphyrin

    Science.gov (United States)

    Wan, Yong; Xue, Yuxiong; Sheng, Ning; Rui, Guanghao; Lv, Changgui; He, Jun; Gu, Bing; Cui, Yiping

    2018-06-01

    The fluorescence and effective three-photon absorption (3PA) properties of Zn(II)-[meso-tetrakis(4-octyloxyphenyl)porphyrin] (labeled Zn(II)-porphyrin) dissolved in three different polar solvents were systematically investigated. The electrochemical and photophysical properties of Zn(II)-porphyrin were investigated by 1H NMR spectra, IR spectra, mass spectroscopy, and electronic absorption spectra. The fluorescence emission of Zn(II)-porphyrin in three different solvents excited at the wavelengths of 420 nm (Soret band) and 550 nm (Q-band) were analyzed. By performing Z-scan experiments with femtosecond laser pulses at a wavelength of 800 nm, the effective 3PA process of Zn(II)-porphyrin in three different solvents was observed and the underlying mechanism was discussed in detail. It is found that the fluorescence spectra slightly depend on the polarity of the solvent. Interestingly, the effective 3PA properties of Zn(II)-porphyrin strongly depend on the solvent polarity. The lower the solvent polarity is, the larger effective 3PA cross-section is. Low polar solvents are beneficial to applications of Zn(II)-porphyrin in optical limiting, photodynamic therapy, etc.

  16. Enhancement of thermal stability of silver(I) acetylacetonate by platinum(II) acetylacetonate

    Czech Academy of Sciences Publication Activity Database

    Křenek, T.; Kovářík, T.; Pola, M.; Jakubec, Ivo; Bezdička, Petr; Bastl, Zdeněk; Pokorná, Dana; Urbanová, Markéta; Galíková, Anna; Pola, Josef

    2013-01-01

    Roč. 554, FEB (2013), s. 1-7 ISSN 0040-6031 Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:67985858 Keywords : thermal gravimetric analysis * differential scanning calorimetry * silver(I) acetylacetonate * platinum(II) acetylacetonate * enhancement of thermal stability Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 2.105, year: 2013

  17. C60 Recognition from Extended Tetrathiafulvalene Bis-acetylide Platinum(II) Complexes.

    Science.gov (United States)

    Bastien, Guillaume; Dron, Paul I; Vincent, Manon; Canevet, David; Allain, Magali; Goeb, Sébastien; Sallé, Marc

    2016-11-18

    The favorable spatial organization imposed by the square planar 4,4'-di(tert-butyl)-2,2'-bipyridine (dbbpy) platinum(II) complex associated with the electronic and shape complementarity of π-extended tetrathiafulvalene derivatives (exTTF) toward fullerenes is usefully exploited to construct molecular tweezers, which display good affinities for C 60 .

  18. Cis-diamminedichloride platinum II (DDP) in the treatment of penile carcinoma.

    Science.gov (United States)

    Sklaroff, R B; Yagoda, A

    1979-11-01

    Cis-diamminedichloride platinum II (DDP) was administered to eight patients with epidermoid carcinoma of the penis. Three of six adequately treated patients had an objective response: one patient achieved complete remission of 7 months duration and 2 patients had partial remissions of 8 and 2 months, respectively. DDP appears to be an active agent in the treatment of penile carcinoma.

  19. Structure of the Hydrated Platinum(II) Ion And the Cis-Diammine-Platinum(II) Complex in Acidic Aqueous Solution: An EXAFS Study

    Energy Technology Data Exchange (ETDEWEB)

    Jalilehvand, F.; Laffin, L.J.

    2009-05-18

    Careful analysis of Pt L{sub 3}-edge extended X-ray absorption fine structure (EXAFS) spectra shows that the hydrated platinum(II) ion in acidic (HClO{sub 4}) aqueous solution binds four water molecules with the Pt-O bond distance 2.01(2) {angstrom} and one (or two) in the axial position at 2.39(2) {angstrom}. The weak axial water coordination is in accordance with the unexpectedly small activation volume previously reported for water exchange in an interchange mechanism with associative character. The hydrated cis-diammineplatinum(II) complex has a similar coordination environment with two ammine and two aqua ligands strongly bound with Pt-O/N bond distances of 2.01(2) {angstrom} and, in addition, one (or two) axial water molecule at 2.37(2) {angstrom}. This result provides a new basis for theoretical computational studies aiming to connect the function of the anticancer drug cis-platin to its ligand exchange reactions, where usually four-coordinated square planar platinum(II) species are considered as the reactant and product. {sup 195}Pt NMR spectroscopy has been used to characterize the Pt(II) complexes.

  20. Electrochemical Preparation of Platinum Nanoparticles from Bis(acetylacetonato)platinum(II) in Some Aprotic Amide-type Ionic Liquids

    International Nuclear Information System (INIS)

    Sultana, Sharmin; Tachikawa, Naoki; Yoshii, Kazuki; Toshima, Kazunobu; Magagnin, Luca; Katayama, Yasushi

    2017-01-01

    Electrode reaction of bis(acetylacetonato)platinum(II), Pt(acac) 2 , and preparation of platinum (Pt) nanoparticles have been studied in 1-R-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (R = butyl, hexyl and decyl, which are abbreviated as BMPTFSA, HMPTFSA and DMPTFSA, respectively) ionic liquids by means of cyclic voltammetry and rotating disk electrode (RDE) method. Pt(acac) 2 was suggested to be reduced to Pt via a two-electron transfer process at a glassy carbon electrode. The diffusion coefficient of Pt(acac) 2 at 50 °C was estimated to be 1.3 × 10 −7 cm 2 s −1 in BMPTFSA, by RDE measurements. It has been demonstrated that Pt nanoparticles were able to be prepared at the glassy carbon RDE by potentiostatic electrolysis at −1.8 and −2.5 V in the ionic liquids containing Pt(acac) 2 . The prepared nanoparticles were characterized by transmission electron microscopy, energy dispersive X-ray spectroscopy and electron diffraction. No pronounced variation in the average particle sizes of Pt was observed with the rotation rates at the RDE, indicating that the average particle size was independent of the rotation rate or current density. Pt nanoparticles of average sizes of 2.1 ± 0.8, 2.8 ± 0.8 and 3.0 ± 0.8 nm were obtained after electrolysis at −1.8 V with a rotation rate of 1000 rpm in BMPTFSA, HMPTFSA and DMPTFSA, respectively, suggested that the average particle size may depend on the kind of the ionic liquid.

  1. Prophage induction and mutagenicity of a series of anti-tumour platinum(II) and platinum(IV) co-ordination complexes

    NARCIS (Netherlands)

    Mattern, I.E.; Cocchiarella, L.; Kralingen, C.G. van; Lohman, P.H.M.

    1982-01-01

    Eleven platinum compounds with nitrogen donor ligands, previously tested for anti-tumour activity were studied for induction of prophage lambda and for mutagenicity in the Ames assay, with various strains of Salmonella. The compounds included cis and trans isomers of Pt(II) and Pt(IV) complexes and

  2. Update: An efficient synthesis of poly(ethylene glycol)-supported iron(II) porphyrin using a click reaction and its application for the catalytic olefination of aldehydes

    KAUST Repository

    Chinnusamy, Tamilselvi R.; Rodionov, Valentin; Kü hn, Fritz; Reiser, Oliver

    2012-01-01

    The facile synthesis of polyethylene glycol (PEG)-immobilized iron(II) porphyrin using a copper-catalyzed azide-alkyne [3+2] cycloaddition "click" reaction is reported. The prepared complex 5 (PEG-C 51H 39FeN 7O) was found to be an efficient

  3. Photoinduced Electron Transfer of PAMAM Dendrimer-Zinc(II) Porphyrin Associates at Polarized Liquid|Liquid Interfaces.

    Science.gov (United States)

    Nagatani, Hirohisa; Sakae, Hiroki; Torikai, Taishi; Sagara, Takamasa; Imura, Hisanori

    2015-06-09

    The heterogeneous photoinduced electron-transfer reaction of the ion associates between NH2-terminated polyamidoamine (PAMAM) dendrimers and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato zinc(II) (ZnTPPS(4-)) was studied at the polarized water|1,2-dichloroethane (DCE) interface. The positive photocurrent arising from the photoreduction of ZnTPPS(4-) by a lipophilic quencher, decamethylferrocene, in the interfacial region was significantly enhanced by the ion association with the PAMAM dendrimers. The photocurrent response of the dendrimer-ZnTPPS(4-) associates was dependent on the pH condition and on the generation of dendrimer. A few cationic additives such as polyallylamine and n-octyltrimethyammonium were also examined as alternatives to the PAMAM dendrimer, but the magnitude of the photocurrent enhancement was rather small. The high photoreactivity of the dendrimer-ZnTPPS(4-) associates was interpreted mainly as a result of the high interfacial concentration of photoreactive porphyrin units associated stably with the dendrimer which was preferably adsorbed at the polarized water|DCE interface. The photochemical data observed in the second and fourth generation PAMAM dendrimer systems demonstrated that the higher generation dendrimer which can incorporate a porphyrin molecule more completely in the interior is less efficient for the photocurrent enhancement at the interface. These results indicated that the photoreactivity of ionic reactant at a polarized liquid|liquid interface can readily be modified via ion association with the charged dendrimer.

  4. Zeolite-like Metal–Organic Framework (MOF) Encaged Pt(II)-Porphyrin for Anion-Selective Sensing

    KAUST Repository

    Masih, Dilshad

    2018-03-26

    The selectivity and sensitivity of sensors are of great interest to the materials chemistry community, and a lot of effort is now devoted to improving these characteristics. More specifically, the selective sensing of anions is one of the largest challenges impeding the sensing-research area due to their similar physical and chemical behaviors. In this work, platinum–metalated porphyrin (Pt(II)TMPyP) was successfully encapsulated in a rho-type zeolite-like metal–organic framework (rho-ZMOF) and applied for anion-selective sensing. The sensing activity and selectivity of the MOF-encaged Pt(II)TMPyP for various anions in aqueous and methanolic media were compared to that of the free (nonencapsulated) Pt(II)TMPyP. While the photoinduced triplet-state electron transfer of Pt(II)TMPyP showed a very low detection limit for anions with no selectivity, the Pt(II)TMPyP encapsulated in the rho-ZMOF framework possessed a unique chemical structure to overcome such limitations. This new approach has the potential for use in other complex sensing applications, including biosensors, which require ion selectivity.

  5. Selective Magnetic Removal of Pb(II from Aqueous Solution by Porphyrin Linked-Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    H. Ghanbarnejad

    2012-12-01

    Full Text Available The discharge of lead containing effluents into the environment and water bodies is harmful for the human, animals, aquatic flora and fauna. Herein, a novel surface engineered magnetic nanoparticle for removing Pb2+  ions was studied. After surface modification of the magnetite by 3-amino-propyltriethoxysilane (APTES magnetic nanoparticles with covalently linked porphyrins were synthesized. Two atropisomers of  meso-tetrakis(2-carboxy-4-nonylphenyl porphyrin (TCNP were tested to analyze the atropisomeric effect on lead uptake. For characterize the synthesized nanosorbents methods like: Transform Infrared Spectroscopy, X-ray diffraction, Transmission Electron Microscopy and Thermo-Gravimetric Analysis were used. The effects of pH, contact time, sorbent dosage and some co-existing cations were investigated. Regeneration of lead adsorbed material could be possible and the modified magnetic nanoparticles exhibited good reusability. The use of such a system can provide fast and efficient removal of the lead ion by using an external magnetic field. The competitive adsorption tests showed good adsorption selectivity for lead ion.

  6. Porphyrin-functionalized porous polysulfone membrane towards an optical sensor membrane for sorption and detection of cadmium(II)

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lizhi, E-mail: zhaolizhi_phd@163.com [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Li, Min; Liu, Manman; Zhang, Yuecong [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Wu, Chenglin [School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou 317000, Zhejiang Province (China); Zhang, Yuzhong, E-mail: zhangyz2004cn@163.com [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

    2016-01-15

    Highlights: • An optical sensor membrane is prepared by TMPyP and PNaSS-grafted PSF membrane. • The optical sensor membrane shows enhanced sorption for cadmium(II). • Visual and spectrophotometric detection can be achieved. • The functional membrane exhibits good stability and reusability. - Abstract: In this study, an optical sensor membrane was prepared for sorption and detection of cadmium(II) (Cd(II)) in aqueous solution. A polyanion, poly(sodium 4-styrenesulfonate) (PNaSS), was grafted onto the chloromethylated polysulfone (CMPSF) microporous membrane via surface-initiated ATRP. 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin p-toluenesulfonate (TMPyP) was immobilized onto the PNaSS-grafted polysulfone (PSF-PNaSS) membrane through electrostatic interaction. The TMPyP-functionalized membrane exhibited an enhanced sorption for, and distinct color and spectral response to cadmium(II) (Cd(II)) in aqueous solution. Larger immobilization capacity of TMPyP on the membrane led to stronger sorption for Cd(II), and smaller one made the optical sensor have a faster (in minutes) and more sensitive response to the ion. The detection limit study indicated that the functional membrane with proper amount of TMPyP (<0.5 mg/g) could still have color and spectral response to Cd(II) solutions at an extreme low concentration (10{sup −4} mg/L). The optical sensor membrane exhibited good stability and reusability which made it efficient for various sorptive removal and detection applications.

  7. Binding of dioxouranium(VI) and platinum(II) to ribonuclease-S

    Energy Technology Data Exchange (ETDEWEB)

    Marzotto, A [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi

    1976-12-01

    The preferred binding sites of RNase-S to dioxouranium(VI) and platinum(II) has been determined by Wyckoff et al., (J.Biol.Chem., v242, 1967, p.3749; ibid p.3984; ibid v245, 1970, p.305) elaborating protein and of heavy-atom derivatives reported by Wyckoff and coworkers. The major sites are exposed at the surface of the protein molecule and are not directly involved in the biological properties; the coordination geometry of the groups bound to the metal ions have been examined in comparison with model compounds.

  8. GLUT1-mediated selective tumor targeting with fluorine containing platinum(II) glycoconjugates.

    Science.gov (United States)

    Liu, Ran; Fu, Zheng; Zhao, Meng; Gao, Xiangqian; Li, Hong; Mi, Qian; Liu, Pengxing; Yang, Jinna; Yao, Zhi; Gao, Qingzhi

    2017-06-13

    Increased glycolysis and overexpression of glucose transporters (GLUTs) are physiological characteristics of human malignancies. Based on the so-called Warburg effect, 18flurodeoxyglucose-positron emission tomography (FDG-PET) has successfully developed as clinical modality for the diagnosis and staging of many cancers. To leverage this glucose transporter mediated metabolic disparity between normal and malignant cells, in the current report, we focus on the fluorine substituted series of glucose, mannose and galactose-conjugated (trans-R,R-cyclohexane-1,2-diamine)-2-flouromalonato-platinum(II) complexes for a comprehensive evaluation on their selective tumor targeting. Besides highly improved water solubility, these sugar-conjugates presented improved cytotoxicity than oxaliplatin in glucose tranporters (GLUTs) overexpressing cancer cell lines and exhibited no cross-resistance to cisplatin. For the highly water soluble glucose-conjugated complex (5a), two novel in vivo assessments were conducted and the results revealed that 5a was more efficacious at a lower equitoxic dose (70% MTD) than oxaliplatin (100% MTD) in HT29 xenograft model, and it was significantly more potent than oxaliplatin in leukemia-bearing DBA/2 mice as well even at equimolar dose levels (18% vs 90% MTD). GLUT inhibitor mediated cell viability analysis, GLUT1 knockdown cell line-based cytotoxicity evaluation, and platinum accumulation study demonstrated that the cellular uptake of the sugar-conjugates was regulated by GLUT1. The higher intrinsic DNA reactivity of the sugar-conjugates was confirmed by kinetic study of platinum(II)-guanosine adduct formation. The mechanistic origin of the antitumor effect of the fluorine complexes was found to be forming the bifunctional Pt-guanine-guanine (Pt-GG) intrastrand cross-links with DNA. The results provide a rationale for Warburg effect targeted anticancer drug design.

  9. 4D-π-1A type β-substituted ZnII-porphyrins: ideal green sensitizers for building-integrated photovoltaics.

    Science.gov (United States)

    Covezzi, A; Orbelli Biroli, A; Tessore, F; Forni, A; Marinotto, D; Biagini, P; Di Carlo, G; Pizzotti, M

    2016-10-18

    Two novel green β-substituted Zn II -porphyrins, G1 and G2, based on a 4D-π-1A type substitution pattern have been synthesized. Their enhanced push-pull character, by reduction of H-L energy gaps, promotes broadening and red-shifting of absorption bands. The effective synthetic pathway and the remarkable spectroscopic properties make G2 ideal for BIPV application.

  10. Zinc (II) [tetra(4-methylphenyl)] Porphyrin: a Novel and Reusable Catalyst for Efficient Synthesis of 2,4,5-trisubstituted Imidazoles Under Ultrasound Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Safari, Javad; Khalili, Shiva Dehghan; Banitaba, Sayed Hossein; Dehghani, Hossein [Univ. of Kashan, Kashan (Iran, Islamic Republic of)

    2011-10-15

    An efficient three-component one-step synthesis of 2,4,5-trisubstituted imidazoles by condensation reaction of 1,2-diketones or α-hydroxyketones with aromatic aldehydes and ammonium acetate using Zinc (II) [tetra (4-methylphenyl)] porphyrin as a novel and reusable catalyst under ultrasound irradiation at ambient temperature is described. In this method, α-hydroxyketones as well as 1,2-diketones were converted to their corresponding 2,4,5-trisubstituted imidazoles in excellent yields.

  11. Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

    Science.gov (United States)

    Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

    2014-10-03

    The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Platinum(II)-gadolinium(III) complexes as potential single-molecular theranostic agents for cancer treatment.

    Science.gov (United States)

    Zhu, Zhenzhu; Wang, Xiaoyong; Li, Tuanjie; Aime, Silvio; Sadler, Peter J; Guo, Zijian

    2014-11-24

    Theranostic agents are emerging multifunctional molecules capable of simultaneous therapy and diagnosis of diseases. We found that platinum(II)-gadolinium(III) complexes with the formula [{Pt(NH3)2Cl}2GdL](NO3)2 possess such properties. The Gd center is stable in solution and the cytoplasm, whereas the Pt centers undergo ligand substitution in cancer cells. The Pt units interact with DNA and significantly promote the cellular uptake of Gd complexes. The cytotoxicity of the Pt-Gd complexes is comparable to that of cisplatin at high concentrations (≥0.1 mM), and their proton relaxivity is higher than that of the commercial magnetic resonance imaging (MRI) contrast agent Gd-DTPA. T1-weighted MRI on B6 mice demonstrated that these complexes can reveal the accumulation of platinum drugs in vivo. Their cytotoxicity and imaging capabilities make the Pt-Gd complexes promising theranostic agents for cancer treatment. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Synthesis and characterization of platinum(II) complexes with 2,2'-bipyridine derivative supporting ligands.

    Science.gov (United States)

    Yang, Kwang Woon; Hwang, Hey Eun; Jung, Hee Sun; Kwak, Chee Hun; Lee, Ji Hoon; Jung, Sang-Chul; Ahn, Ho Geun; Chung, Min Chul

    2011-08-01

    The reaction of the [Pt(bpy-R)Cl2](bpy-R: R=H (2,2'-bipyridine); R=CH3 (4,4'-dimethyl-2,2'-biypridine (DM-bpy), 3,3'-5,5'-tertamethyl-2,2'-bipyridiyl (TM-bpy)) with 1,4-Bis(5'-2',2"-bipyridine)benzene (bpy-Ph-bpy) affords the following mono- and di-platinum complexes of [(bpy)Pt(bpy-Ph-bpy)][PF6]2 (1), [(bpy)Pt(bpy-Ph-bpy)Pt(bpy)])[PF6]4 (2), [(DM-bpy)Pt(bpy-Ph-bpy)])][PF6]2 (3), and [(TM-bpy)Pt(bpy-ph-bpy)[PF6]2 (4), respectively. These complexes were characterized by NMR, IR, UV/VIS, PL and cyclic voltammetry. The internal quantum yields of these platinum(II) complexes are very high (0.83-0.99) and these complexes emit light at deep blue regions (373-417 nm). The redox behavior of complexes 1 and 2 shows quasi-reversible process.

  14. 4-aminoquinoline analogues and its platinum (II) complexes as antimalarial agents.

    Science.gov (United States)

    de Souza, Nicolli Bellotti; Carmo, Arturene M L; Lagatta, Davi C; Alves, Márcio José Martins; Fontes, Ana Paula Soares; Coimbra, Elaine Soares; da Silva, Adilson David; Abramo, Clarice

    2011-07-01

    The high incidence of malaria and drug-resistant strains of Plasmodium have turned this disease into a problem of major health importance. One of the approaches used to control it is to search for new antimalarial agents, such as quinoline derivates. This class of compounds composes a broad group of antimalarial agents, which are largely employed, and inhibits the formation of β-haematin (malaria pigment), which is lethal to the parasite. More specifically, 4-aminoquinoline derivates represent potential sources of antimalarials, as the example of chloroquine, the most used antimalarial worldwide. In order to assess antimalarial activity, 12 4-aminoquinoline derived drugs were obtained and some of these derivatives were used to obtain platinum complexes platinum (II). These compounds were tested in vivo in a murine model and revealed remarkable inhibition of parasite multiplication values, whose majority ranged from 50 to 80%. In addition they were not cytotoxic. Thus, they may be object of further research for new antimalarial agents. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  15. Synthesis, structural characterization, and pro-apoptotic activity of 1-indanone thiosemicarbazone platinum(II) and palladium(II) complexes: potential as antileukemic agents.

    Science.gov (United States)

    Gómez, Natalia; Santos, Diego; Vázquez, Ramiro; Suescun, Leopoldo; Mombrú, Alvaro; Vermeulen, Monica; Finkielsztein, Liliana; Shayo, Carina; Moglioni, Albertina; Gambino, Dinorah; Davio, Carlos

    2011-08-01

    In the search for alternative chemotherapeutic strategies against leukemia, various 1-indanone thiosemicarbazones, as well as eight novel platinum(II) and palladium(II) complexes, with the formula [MCl₂(HL)] and [M(HL)(L)]Cl, derived from two 1-indanone thiosemicarbazones were synthesized and tested for antiproliferative activity against the human leukemia U937 cell line. The crystal structure of [Pt(HL1)(L1)]Cl·2MeOH, where L1=1-indanone thiosemicarbazone, was solved by X-ray diffraction. Free thiosemicarbazone ligands showed no antiproliferative effect, but the corresponding platinum(II) and palladium(II) complexes inhibited cell proliferation and induced apoptosis. Platinum(II) complexes also displayed selective apoptotic activity in U937 cells but not in peripheral blood monocytes or the human hepatocellular carcinoma HepG2 cell line used to screen for potential hepatotoxicity. Present findings show that, in U937 cells, 1-indanone thiosemicarbazones coordinated to palladium(II) were more cytotoxic than those complexed with platinum(II), although the latter were found to be more selective for leukemic cells suggesting that they are promising compounds with potential therapeutic application against hematological malignancies. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. N6-Benzyladenosine Derivatives as Novel N-Donor Ligands of Platinum(II Dichlorido Complexes

    Directory of Open Access Journals (Sweden)

    Ján Vančo

    2013-06-01

    Full Text Available The platinum(II complexes trans-[PtCl2(Ln2]∙xSolv 1–13 (Solv = H2O or CH3OH, involving N6-benzyladenosine-based N-donor ligands, were synthesized; Ln stands for N6-(2-methoxybenzyladenosine (L1, involved in complex 1, N6-(4-methoxy-benzyladenosine (L2, 2, N6-(2-chlorobenzyladenosine (L3, 3, N6-(4-chlorobenzyl-adenosine (L4, 4, N6-(2-hydroxybenzyladenosine (L5, 5, N6-(3-hydroxybenzyl-adenosine (L6, 6, N6-(2-hydroxy-3-methoxybenzyladenosine (L7, 7, N6-(4-fluoro-benzyladenosine (L8, 8, N6-(4-methylbenzyladenosine (L9, 9, 2-chloro-N6-(3-hydroxy-benzyladenosine (L10, 10, 2-chloro-N6-(4-hydroxybenzyladenosine (L11, 11, 2-chloro-N6-(2-hydroxy-3-methoxybenzyladenosine (L12, 12 and 2-chloro-N6-(2-hydroxy-5-methylbenzyladenosine (L13, 13. The compounds were characterized by elemental analysis, mass spectrometry, IR and multinuclear (1H-, 13C-, 195Pt- and 15N- and two-dimensional NMR spectroscopy, which proved the N7-coordination mode of the appropriate N6-benzyladenosine derivative and trans-geometry of the title complexes. The complexes 1–13 were found to be non-toxic in vitro against two selected human cancer cell lines (HOS and MCF7; with IC50 > 50.0 µM. However, they were found (by ESI-MS study to be able to interact with the physiological levels of the sulfur-containing biogenic biomolecule L-methionine by a relatively simple 1:1 exchange mechanism (one Ln molecule was replaced by one L-methionine molecule, thus forming a mixed-nitrogen/sulfur-ligand dichlorido-platinum(II coordination species.

  17. Interaction of Cu(II)-meso-tetrakis(n-N-methylpyridiniumyl)porphyrin (n = 2,3,4) with Native and Synthetic Polynucleotides Probed by Polarized Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Mi Jin; Kim, Seog K.; Kim, Jong Moon; Lee, Dong Jin; Lee, Gil Jun

    2005-01-01

    The interactions of Cu(II)-meso-Tetrakis(n-N-methylpyridiniumyl)porphyrin (n = 2,3,4), respectively referred to as o-, m- and p-CuTMPyP, and DNA, poly[d(A-T) 2 ] and poly[d(G-C) 2 ] were investigated by circular and linear dichroism (CD and LD). In the o-CuTMPyP case, in which the rotation of the pyridinium ring is prevented, the shape of the CD spectrum when associated to DNA and poly[d(A-T) 2 ] resembles and is characterized by a positive band at a low drug to DNA concentration ratio (R ratio) and is bisignate at a high R ratio. The former CD spectrum shape has been attributed to porphyrin that is bound monomerically outside of DNA while the latter can be attributed to those that are stacked. When o-CuTMPyP is bound to poly[d(G-C) 2 ], the excitonic CD appeared at a relatively high R ratio. In contrast, a characteristic negative CD band in the Soret region was apparent for both m- and p-CuTMPyP when bound to DNA and poly[d(G-C) 2 ] at the low R ratios, indicating that the porphyrin molecule intercalates. However, the DNA is bent near the intercalation site and the plane of the porphyrin molecule tilts relative to the DNA helix axis, as judged by the magnitude of the reduced LD. Various stacking patterns were identified by the shape of the CD spectrum for m- and p-CuTMPyP when bound to poly[d(A-T) 2 ]. Three species for the former complex and two for the latter complex were found which may reflect the extent of the stacking

  18. Molecular-wire behavior of OLED materials: exciton dynamics in multichromophoric Alq3-oligofluorene-Pt(II)porphyrin triads.

    Science.gov (United States)

    Montes, Victor A; Pérez-Bolívar, César; Agarwal, Neeraj; Shinar, Joseph; Anzenbacher, Pavel

    2006-09-27

    Donor-bridge-acceptor triads consisting of the Alq3 complex, oligofluorene bridge, and PtII tetraphenylporphyrin (PtTPP) were synthesized. The triads were designed to study the energy level/distance-dependence in energy transfer both in a solution and in solid state. The materials show effective singlet transfer from the Alq3-fluorene fluorophore to the porphyrin, while the triplet energy transfer, owing to the shorter delocalization of triplet excitons, appears to take place via a triplet energy cascade. Using femtosecond transient spectroscopy, the rate of the singlet-singlet energy transfer was determined. The exponential dependence of the donor-acceptor distance and the respective energy transfer rates of 7.1 x 1010 to 1.0 x 109 s-1 with the attenuation factor â of 0.21 +/- 0.02 A-1 suggest that the energy transfer proceeds via a mixed incohererent wire/superexchange mechanism. In the OLEDs fabricated using the Alq3-oligofluorene-PtTPP triads with better triplet level alignment, the order of a magnitude increase in efficacy appears to be due to facile triplet energy transfer. The devices, where the triplet-triplet energy transfer is of paramount importance, showed high color purity emission (CIE X,Y: 0.706, 0.277), which is almost identical to the emission from thin films. Most importantly, we believe that the design principles demonstrated above are general and may be used to prepare OLED materials with enhanced quantum efficacy at lowered operational potentials, being crucial for improved lifespan of OLEDs.

  19. Update: An efficient synthesis of poly(ethylene glycol)-supported iron(II) porphyrin using a click reaction and its application for the catalytic olefination of aldehydes

    KAUST Repository

    Chinnusamy, Tamilselvi R.

    2012-05-09

    The facile synthesis of polyethylene glycol (PEG)-immobilized iron(II) porphyrin using a copper-catalyzed azide-alkyne [3+2] cycloaddition "click" reaction is reported. The prepared complex 5 (PEG-C 51H 39FeN 7O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG-supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Iron(III) and copper(II) complexes of trans-bis(ferrocenyl)porphyrin ...

    Indian Academy of Sciences (India)

    a single two-electron quasi-reversible process compared to the free base ligand in which two 1e-oxidative response separated by ... electron redox catalysis and can be used for multi- .... 0.26 x 0.22 x 0.18. Formula weight. 892.09. Crystal system. Monoclinic. Color. Dark red .... A perspective view of CuII(Fc2Ph2P) showing.

  1. Solid solutions of platinum(II) and palladium(II) oxalato-complex salt as precursors of nanoalloys

    Science.gov (United States)

    Zadesenets, A. V.; Asanova, T. I.; Vikulova, E. S.; Filatov, E. Yu.; Plyusnin, P. E.; Baidina, I. A.; Asanov, I. P.; Korenev, S. V.

    2013-03-01

    A solid solution of platinum (II) and palladium (II) oxalato-complex salt, (NH4)2[Pt0.5Pd0.5(C2O4)2]·2H2O, has been synthesized and studied as a precursor for preparing bimetallic PtPd nanoparticles through its thermal decomposition. The smallest homogenous bimetallic PtPd nanoparticles were found to form in hydrogen and helium atmospheres. The annealing temperature and time have low effect on the bimetallic particles size. Comparative analysis of structural and thermal properties of the solid solution and individual Pt, Pd oxalato-complex salts was performed to investigate a mechanism of thermal decomposition of (NH4)2[Pt0.5Pd0.5(C2O4)2]·2H2O. Based on in situ X-ray photoemission spectroscopy investigation it was proposed a mechanism of formation of bimetallic PtPd nanoparticles from the solid-solution oxalato-complex salt during thermal decomposition.

  2. Electrochemical and SEM studies of tetra-ammine platinum (II) (Pt(NH3)4)(OH)2 solution

    International Nuclear Information System (INIS)

    Wan Jeffrey Basirun

    2002-01-01

    Electrochemical studies include cyclic voltammetry with microelectrodes were done on a solution of tetra-ammine platinum (II) (Pt(NH 3 ) 4 )(OH) 2 at pH 13 and showed that the electrochemical reduction of this compound was no different from the tetra-ammine platinum (II) (Pt(NH 3 ) 4 )(HPO 4 ) at pH 10.4. The solution was instable to high temperatures and results have shown that electroplating can be done at a limited temperature range for longer periods of time or at higher temperatures for short periods of time. Scanning electron microscopy was done on some of the constant current electrodeposited samples at high temperatures and result obtained was satisfactory. (Authors)

  3. Interaction of Newly Platinum(II) with Tris(2-carboxyethyl)phosphine Complex with DNA and Model Lipid Membrane

    Czech Academy of Sciences Publication Activity Database

    Pruchnik, H.; Kral, Teresa; Hof, Martin

    2017-01-01

    Roč. 250, č. 5 (2017), s. 461-470 ISSN 0022-2631 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388955 Keywords : dna * DPPC bilayer * dsc * IR spectroscopy * Platinum(II) complex * tcspc-fcs Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.696, year: 2016

  4. Binding of palladium (II) 5, 10, 15, 20-tetrakis (4-sulfonatophenyl) porphyrin to a lectin for photosensitizer targeted delivery

    Czech Academy of Sciences Publication Activity Database

    Bogoeva, V.; Petrova, L.; Kubát, Pavel

    2015-01-01

    Roč. 153, DEC 2015 (2015), s. 276-280 ISSN 1011-1344 R&D Projects: GA ČR GA13-12496S Institutional support: RVO:61388955 Keywords : palladium porphyrin * concavalin A * fluorescence Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.035, year: 2015

  5. Photodynamic killing of cancer cells by a Platinum(II) complex with cyclometallating ligand

    Science.gov (United States)

    Doherty, Rachel E.; Sazanovich, Igor V.; McKenzie, Luke K.; Stasheuski, Alexander S.; Coyle, Rachel; Baggaley, Elizabeth; Bottomley, Sarah; Weinstein, Julia A.; Bryant, Helen E.

    2016-03-01

    Photodynamic therapy that uses photosensitizers which only become toxic upon light-irradiation provides a strong alternative to conventional cancer treatment due to its ability to selectively target tumour material without affecting healthy tissue. Transition metal complexes are highly promising PDT agents due to intense visible light absorption, yet the majority are toxic even without light. This study introduces a small, photostable, charge-neutral platinum-based compound, Pt(II) 2,6-dipyrido-4-methyl-benzenechloride, complex 1, as a photosensitizer, which works under visible light. Activation of the new photosensitizer at low concentrations (0.1-1 μM) by comparatively low dose of 405 nm light (3.6 J cm-2) causes significant cell death of cervical, colorectal and bladder cancer cell lines, and, importantly, a cisplatin resistant cell line EJ-R. The photo-index of the complex is 8. We demonstrate that complex 1 induces irreversible DNA single strand breaks following irradiation, and that oxygen is essential for the photoinduced action. Neither light, nor compound alone led to cell death. The key advantages of the new drug include a remarkably fast accumulation time (diffusion-controlled, minutes), and photostability. This study demonstrates a highly promising new agent for photodynamic therapy, and attracts attention to photostable metal complexes as viable alternatives to conventional chemotherapeutics, such as cisplatin.

  6. Synthesis and coordination behavior of a bipyridine platinum(II) complex with thioglucose.

    Science.gov (United States)

    Tsuji, Takaaki; Kuwamura, Naoto; Yoshinari, Nobuto; Konno, Takumi

    2013-05-06

    A mononuclear platinum(II) complex with two monodentate-S H4tg(-) ligands, [Pt(H4tg-κS)2(bpy)] (1), was newly synthesized by the reaction of [PtCl2(bpy)] (bpy = 2,2'-bipyridyl) with NaH4tg (NaH4tg =1-thio-β-d-glucose sodium salt) in water. Complex 1 reacted with additional [PtCl2(bpy)] in water to give an S-bridged dinuclear complex, [Pt2(μ2-H4tg-κ(1)S:κ(1)S)2(bpy)2](2+) ([2](2+)), in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [Pt(bpy)](2+) moiety through two thiolato groups. Treatments of 1 with Cu(2+) and Ni(2+) in water in the presence of bpy produced S-bridged dinuclear complexes [PtCu(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([3](2+)) and [PtNi(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([4](2+)), respectively, in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [M(bpy)](2+) (M = Cu(II), Ni(II)) moiety through two thiolato and two hydroxyl groups to form a chiral [M(N)2(O)2(S)2] octahedron with the Δ configuration. On the other hand, similar treatment with Cd(2+) in the presence of bpy resulted in the formation of an S-bridged trinuclear complex, [Cd{Pt(μ2-H4tg-κ(1)S:κ(2)O,S)(μ2-H4tg-κ(1)S:κ(1)S)(bpy)}2](2+) ([5](2+)), in which each of two square-planar [Pt(H4tg)2(bpy)] units binds to a Cd(II) ion through two thiolato groups and one hydroxyl group to form a chiral [Cd(O)2(S)4] octahedron with the Λ configuration. Of two geometrical configurations, syn and anti, which arise from the relative arrangement of two β-D-pyranose moieties, [2](2+) adopts the syn configuration with symmetric bridging sulfur atoms, while [3](2+), [4](2+), and [5](2+) all have the anti configuration with R configurational bridging sulfur atoms. All of the complexes were fully characterized by electronic absorption, CD, and NMR spectroscopies, along with single-crystal X-ray crystallography.

  7. Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

    KAUST Repository

    Goswami, Subhadip

    2014-12-18

    A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores\\' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores\\' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

  8. Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

    KAUST Repository

    Goswami, Subhadip; Winkel, Russell W.; Alarousu, Erkki; Ghiviriga, Ion; Mohammed, Omar F.; Schanze, Kirk S.

    2014-01-01

    A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

  9. Porphyrin amino acids-amide coupling, redox and photophysical properties of bis(porphyrin) amides.

    Science.gov (United States)

    Melomedov, Jascha; Wünsche von Leupoldt, Anica; Meister, Michael; Laquai, Frédéric; Heinze, Katja

    2013-07-14

    New trans-AB2C meso-substituted porphyrin amino acid esters with meso-substituents of tunable electron withdrawing power (B = mesityl, 4-C6H4F, 4-C6H4CF3, C6F5) were prepared as free amines 3a-3d, as N-acetylated derivatives Ac-3a-Ac-3d and corresponding zinc(II) complexes Zn-Ac-3a-Zn-Ac-3d. Several amide-linked bis(porphyrins) with a tunable electron density at each porphyrin site were obtained from the amino porphyrin precursors by condensation reactions (4a-4d) and mono- and bis(zinc(II)) complexes Zn(2)-4d and Zn(1)Zn(2)-4d were prepared. The electronic interaction between individual porphyrin units in bis(porphyrins) 4 is probed by electrochemical experiments (CV, EPR), electronic absorption spectroscopy, steady-state and time-resolved fluorescence spectroscopy in combination with DFT/PCM calculations on diamagnetic neutral bis(porphyrins) 4 and on respective charged mixed-valent radicals 4(+/-). The interaction via the -C6H4-NHCO-C6H4- bridge, the site of oxidation and reduction and the lowest excited singlet state S1, is tuned by the substituents on the individual porphyrins and the metalation state.

  10. Mono(p-tolyl)platinum(II) and bis(p-tolyl)platinum(II) complexes of diethylsulfide as reagents for organoplatinum synthesis. Structures of [Pt(p-Tol)2(µ-SEt2)]2 and PtCl(p-Tol)(bpy) (bpy = 2,2'-bipyridine)

    NARCIS (Netherlands)

    Koten, G. van; Casado Lacabra, M.A.; Canty, A.J.; Lutz, M.H.; Patel, J.; Spek, A.L.; Sun, H.

    2001-01-01

    The complex trans-PtCl(p-Tol)(SEt{2}){2} is obtained from the reaction of [Pt(p-Tol){2}(SEt{2})]{2} with PtCl{2}(SEt{2}){2} and SEt{2} in mole ratio 1:2:2. The mono(p-tolyl)platinum(II) and bis(p-tolyl)platinum(II) complexes of diethylsulfide react with 2, 2'-bipyridine to form the complexes

  11. Synthesis of Zn(II) 5,10,15,20-tetrakis(4'-isopropylphenyl) porphyrin and its use as a thin film sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sayyad, Muhammad H.; Saleem, Muhammad [GIK Institute of Engineering Sciences and Technology, Faculty of Engineering Sciences (FES), Topi, District Swabi, NWFP (Pakistan); Karimov, Khasan S. [GIK Institute of Engineering Sciences and Technology, Faculty of Engineering Sciences (FES), Topi, District Swabi, NWFP (Pakistan); Physical Technical Institute of Academy of Sciences, Dushanbe (Tajikistan); Yaseen, Muhammad [University of the Punjab, Institute of Chemistry, Lahore (Pakistan); Ali, Mukhtar [Government College of Science, Lahore (Pakistan); Cheong, Kuan Y.; Mohd Noor, Ahmad F. [Universiti Sains Malaysia, School of Materials and Mineral Resources Engineering, Engineering Campus, Nibong Tebal, Penang (Malaysia)

    2010-01-15

    In this paper, we have reported the synthesis and use of an organic semiconductor Zn(II) 5,10,15,20-tetrakis(4'-isopropylphenyl) porphyrin (ZnTIPP) as an active material in a surface type sensor. Ag/ZnTIPP/Ag sensor was fabricated by thermal sublimation of ZnTIPP on a glass substrate with preliminary deposited surface type silver electrodes. Semiconducting channel between silver electrodes was 0.04 mm x 15 mm. Changes in electrical measurements of the device were observed with increase of relative humidity, illumination, and temperature. A small degree of hysteresis and acceptable response and recovery times were observed over a wide range of relative humidity. Activation energy of the ZnTIPP was estimated. (orig.)

  12. Novel polar sedimentary porphyrins

    Science.gov (United States)

    Prowse, W. G.; Maxwell, J. R.

    1989-11-01

    Two polar nickel porphyrins in Messel oil shale are shown to be the C 32 and C 30 components IIIa,b. In the sample examined, component IIIa is by far the major porphyrin alcohol and is present in an abundance similar to that of the major nickel alkyl porphyrin. These primary alcohols, which do not appear to be artifacts, are structurally related to alkyl porphyrins reported previously in Serpiano oil shale.

  13. Unique DNA binding mode of antitumor trinuclear tridentate platinum(II) compound

    Czech Academy of Sciences Publication Activity Database

    Olivová, R.; Kašpárková, Jana; Vrána, Oldřich; Vojtíšková, Marie; Suchánková, T.; Nováková, Olga; He, W.; Guo, Z.; Brabec, Viktor

    2011-01-01

    Roč. 8, č. 6 (2011), s. 2368-2378 ISSN 1543-8384 R&D Projects: GA MŠk(CZ) ME10066 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : platinum * antitumor * DNA Subject RIV: BO - Biophysics Impact factor: 4.782, year: 2011

  14. Inverted porphyrins and expanded porphyrins: An overview

    Indian Academy of Sciences (India)

    Unknown

    More recently, synthetic porphyrins and porphyrin-like macrocycles have ... one of the meso carbons resulting in the formation of corroles; – (d) Isomeric ... spectroscopic, chemical and physical properties, which can find applications in ..... diol 55 under TFA catalysis yielding 20–28% yield of expected rubyrins 85 and 86 as.

  15. Synthesis, crystal structure and anticancer activity of tetrakis(N-isopropylimidazolidine-2-selenone)platinum(II) chloride

    Science.gov (United States)

    Ahmad, Saeed; Altoum, Ali Osman S.; Vančo, Ján; Křikavová, Radka; Trávníček, Zdeněk; Dvořák, Zdeněk; Altaf, Muhammad; Sohail, Manzar; Isab, Anvarhusein A.

    2018-01-01

    A Platinum(II) complex of N-isopropylimidazolidine-2-selenone (i-PrImSe), [Pt(i-PrImSe)4]Cl2 (1) was prepared and characterized by elemental analysis, IR and NMR (1H, 13C, 77Se &195Pt) spectroscopy, and X-ray crystallography. The structure of 1 consists of [Pt(i-PrImSe)4]2+ complex ion and chloride counter ions. The platinum(II) atom adopts a distorted square planar geometry. The in vitro antitumor activity of 1 as well as cisplatin, was evaluated by MTT assay against human; ovarian carcinoma A2780 and its cisplatin-resistant subline A2780R, prostate cancer 22Rv1 and breast cancer MCF-7 cell lines. The title complex displayed the activity against the A2780 cells (IC50 = 30.8 μM) at the level comparable to cisplatin (IC50 = 26.8 μM). The interaction studies with sulfur-containing biomolecules revealed its ability to form a variety of intermediates and oxidized species with L-cysteine and reduced glutathione.

  16. Relative cytotoxicity of complexes of platinum(II and palladium(II against pure cell culture Paramecium caudatum and human cell lines A431 and HaCaT

    Directory of Open Access Journals (Sweden)

    Aleksei Vladimirovich Eremin

    2018-04-01

    Full Text Available The results of cytotoxicity cisplatin-like complexes of platinum(II and palladium(II are presented. The cytotoxicity was researched by method of  biotesting with Paramecium caudatum and by MTT-assay with human cells: epidermoid carcimoma A431 and minimal transformed aneuploid keratinocytes HaCaT. Cytotoxicity of complexes toward protists is high, however, comparatively HaCaT are more sensitive than A431. Furthemore, cytotoxicity of palladium(II complexes is higher than the analogues with platinum(II.

  17. Thin porphyrin composite membranes with enhanced organic solvent transport

    KAUST Repository

    Phuoc, Duong

    2018-05-01

    Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block. Hybrid polyamide films are formed by interfacial polymerization of 5,10,15,20-(tetra-4-aminophenyl)porphyrin/m-phenylene diamine (MPD) mixtures with trimesoyl chloride. Porphyrin is a non-planar molecule, containing a heterocyclic tetrapyrrole unit. Its incorporation into a polyamide film leads to higher free volume than that of a standard polyamide film. Polyamide films derived from porphyrin and MPD amines with a fixed total amine concentration of 1wt% and various porphyrin/MPD ratios were fabricated and characterized. The porphyrin/MPD polyamide film was complexed with Cu(II), due to the binding capacity of porphyrin to metal ions. By coupling scanning transmission electron microscopy (STEM) with electron energy-loss spectroscopy (EELS), Cu mapping was obtained, revealing the distribution of porphyrin in the interfacial polymerized layer. By using porphyrin as amine-functionalized monomer a membrane with thin selective skin and enhanced solvent transport is obtained, with good dye selectivity in the nanofiltration range. For instance, an ultra-fast hexane permeance, 40-fold increased, was confirmed when using 0.5/0.5 porphyrin/MPD mixtures, instead of only MPD as amine monomer. A rejection of 94.2% Brilliant Blue R (826g/mol) in methanol was measured.

  18. A Potential Bone-Targeting Hypotoxic Platinum(II) Complex with an Unusual Cytostatic Mechanism toward Osteosarcoma Cells.

    Science.gov (United States)

    Zhang, Zhenqin; Zhu, Zhenzhu; Luo, Cheng; Zhu, Chengcheng; Zhang, Changli; Guo, Zijian; Wang, Xiaoyong

    2018-03-19

    Osteosarcoma (OS) is the most common primary pediatric bone tumor lethal to children and adolescents. Chemotherapeutic agents such as cisplatin are not effective for OS because of their poor accessibility to this cancer and severe systemic toxicity. In this study, a lipophilic platinum(II) complex bearing a bisphosphonate bone-targeting moiety, cis-[PtL(NH 3 ) 2 Cl]NO 3 {BPP; L = tetraethyl [2-(pyridin-2-yl)ethane-1,1-diyl]bisphosphonate}, was prepared and characterized by NMR, electrospray ionization mass spectrometry, and single-crystal X-ray crystallography. The cytotoxicity of BPP toward OS cell lines U2OS and MG-63 was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. BPP exhibits moderate inhibition against U2OS cells through a mechanism involving both DNA binding and a mevalonate pathway. The acute toxicity of BPP to mice is 7-fold lower than that of cisplatin. The relative low systemic toxicity may result from the steric hindrance of the ligand, which blocks BPP approaching the bases of DNA. The results suggest that incorporating bisphosphonates into a platinum complex not only enhances its bone-targeting property but also minimizes its reactivity toward DNA and thereby lowers the systematic toxicity of the complex. The diminished cytotoxicity of BPP could be compensated for by increasing the therapeutic dose with marginal harm. This strategy provides a new possibility for overcoming the ineffectiveness and systemic toxicity of platinum drugs in the treatment of OS.

  19. Trans labilization of am(m)ine ligands from platinum(II) complexes by cancer cell extracts.

    Science.gov (United States)

    Kasherman, Yonit; Sturup, Stefan; Gibson, Dan

    2009-03-01

    Cisplatin, cis-[Pt(NH(3))(2)Cl(2)], is an effective anticancer agent in wide clinical use whose efficacy is affected by cellular interactions with sulfur-containing nucleophiles. These interactions can potentially enhance the efficacy of the drug by mediating its delivery to nuclear DNA or inactivate the drug by binding to it irreversibly or by labilizing the NH(3) ligands. Despite the potential importance of trans-labilization reactions in the mechanism of action of the drug, few detailed studies on trans labilization of the ammines have been conducted. We used 2D NMR to show that some trans labilization occurs in proliferating cells and that aqueous extracts of cancer cells labilized 20% of the amine ligands of cis-[PtCl(2)((13)CH(3)NH(2))(2)] after a 12-h incubation. Both low molecular mass nucleophiles (less than 3 kDa) and high molecular mass nucleophiles (more than 3 kDa) labilize the amines with similar efficiency. Studies with model compounds show that thiols and thioethers bind to platinum(II) at similar rates, but thioethers are significantly more efficient at labilizing the am(m)ine at lower pH. N-Acetylcysteine is a more efficient trans-labilizer than glutathione, suggesting that the displacement of the amine proceeds through an associative mechanism. The lag time, the time that elapses from the formation of the Pt-S bond till the release of the amine trans to the sulfur, depends on the pH (for thiols), increasing at lower pH. Quantification of the platinum adducts obtained from incubation of cisplatin with cell extracts indicates that two thirds of the platinum is bound to cellular components with molecular mass greater than 3 kDa.

  20. Supramolecular Allosteric Cofacial Porphyrin Complexes

    International Nuclear Information System (INIS)

    Oliveri, Christopher G.; Gianneschi, Nathan C.; Nguyen, Son Binh T.; Mirkin, Chad A.; Stern, Charlotte L.; Wawrzak, Zdzislaw; Pink, Maren

    2008-01-01

    Nature routinely uses cooperative interactions to regulate cellular activity. For years, chemists have designed synthetic systems that aim toward harnessing the reactivity common to natural biological systems. By learning how to control these interactions in situ, one begins to allow for the preparation of man-made biomimetic systems that can efficiently mimic the interactions found in Nature. To this end, we have designed a synthetic protocol for the preparation of flexible metal-directed supramolecular cofacial porphyrin complexes which are readily obtained in greater than 90% yield through the use of new hemilabile porphyrin ligands with bifunctional ether-phosphine or thioether-phosphine substituents at the 5 and 15 positions on the porphyrin ring. The resulting architectures contain two hemilabile ligand-metal domains (Rh I or Cu I sites) and two cofacially aligned porphyrins (Zn II sites), offering orthogonal functionalities and allowing these multimetallic complexes to exist in two states, 'condensed' or 'open'. Combining the ether-phosphine ligand with the appropriate Rh I or Cu I transition-metal precursors results in 'open' macrocyclic products. In contrast, reacting the thioether-phosphine ligand with RhI or CuI precursors yields condensed structures that can be converted into their 'open' macrocyclic forms via introduction of additional ancillary ligands. The change in cavity size that occurs allows these structures to function as allosteric catalysts for the acyl transfer reaction between X-pyridylcarbinol (where X = 2, 3, or 4) and 1-acetylimidazole. For 3- and 4-pyridylcarbinol, the 'open' macrocycle accelerates the acyl transfer reaction more than the condensed analogue and significantly more than the porphyrin monomer. In contrast, an allosteric effect was not observed for 2-pyridylcarbinol, which is expected to be a weaker binder and is unfavorably constrained inside the macrocyclic cavity.

  1. Photophysical characterisation and studies of the effect of palladium(II) 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin on isometric contraction of isolated human mesenteric artery: Good news for photodynamic therapy

    Czech Academy of Sciences Publication Activity Database

    Dimitrova, D. Z.; Kubát, Pavel; Dimitrov, S.; Belokonski, E.; Bogoeva, V.

    2014-01-01

    Roč. 11, č. 3 (2014), s. 391-399 ISSN 1572-1000 R&D Projects: GA ČR(CZ) GA13-12496S Institutional support: RVO:61388955 Keywords : Palladium(II) 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin * Human mesenteric artery * Isometric contraction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.014, year: 2014

  2. Phase II study of oral platinum drug JM216 as first-line treatment in patients with small-cell long cancer

    NARCIS (Netherlands)

    Fokkema, E; Groen, HJM; Uges, DRA; Weil, C; Smith, IE

    1999-01-01

    Purpose: This multicenter phase II trial wets performed to determine tumor efficacy and tolerance of the oral platinum drug JM216 in patients with small-cell lung cancer (SCLC). Patients and Methods: patients with SCLC limited disease unfit for intensive chemotherapy or those with extensive disease

  3. Phosphorescence parameters for platinum (II) organometallic chromophores: A study at the non-collinear four-component Kohn–Sham level of theory

    DEFF Research Database (Denmark)

    Norman, Patrick; Jensen, Hans Jørgen Aagaard

    2012-01-01

    A theoretical characterization of the phosphorescence decay traces of a prototypical platinum (II) organic chromophore has been conducted. The phosphorescence wavelength and radiative lifetime are predicted to equal 544 nm and 160 μs, respectively. The third triplet state is assigned as participa...

  4. N -annulated perylene as an efficient electron donor for porphyrin-based dyes: Enhanced light-harvesting ability and high-efficiency Co(II/III)-based dye-sensitized solar cells

    KAUST Repository

    Luo, Jie

    2014-01-08

    Porphyrin-based dyes recently have become good candidates for dye-sensitized solar cells (DSCs). However, the bottleneck is how to further improve their light-harvesting ability. In this work, N-annulated perylene (NP) was used to functionalize the Zn-porphyrin, and four "push-pull"-type NP-substituted and fused porphyrin dyes with intense absorption in the visible and even in the near-infrared (NIR) region were synthesized. Co(II/III)-based DSC device characterizations revealed that dyes WW-5 and WW-6, in which an ethynylene spacer is incorporated between the NP and porphyrin core, showed pantochromatic photon-to-current conversion efficiency action spectra in the visible and NIR region, with a further red-shift of about 90 and 60 nm, respectively, compared to the benchmark molecule YD2-o-C8. As a result, the short-circuit current density was largely increased, and the devices displayed power conversion efficiencies as high as 10.3% and 10.5%, respectively, which is comparable to that of the YD2-o-C8 cell (η = 10.5%) under the same conditions. On the other hand, the dye WW-3 in which the NP unit is directly attached to the porphyrin core showed a moderate power conversion efficiency (η = 5.6%) due to the inefficient π-conjugation, and the NP-fused dye WW-4 exhibited even poorer performance due to its low-lying LUMO energy level and nondisjointed HOMO/LUMO profile. Our detailed physical measurements (optical and electrochemical), density functional theory calculations, and photovoltaic characterizations disclosed that the energy level alignment, the molecular orbital profile, and dye aggregation all played very important roles on the interface electron transfer and charge recombination kinetics. © 2013 American Chemical Society.

  5. Preparation and Biological Evaluation of Two Novel Platinum(II Complexes Based on the Ligands of Dipicolyamine Bisphosphonate Esters

    Directory of Open Access Journals (Sweden)

    Ling Qiu

    2016-02-01

    Full Text Available Two new platinum(II-based complexes bearing a bone-targeting group were synthesized and characterized. They both have excellent affinity for hydroxyapatite (HA, which is abundant in human bone tissues. Their antitumor activities against five human cancer cell lines (U2OS, A549, HCT116, MDA-MB-231 and HepG2 were evaluated and compared with cisplatin (CDDP. Though the antitumor efficacies of new complexes are lower than that of CDDP, they show higher selectivity against the HepG2 hepatoma cell line than the L02 normal liver cell line. Morphology studies exhibited typical characteristics of cell apoptosis and the cell cycle distribution analysis indicated that the complexes can inhibit cancer cells by inducing cell cycle arrest at the G2/M phase, a similar mechanism of action to CDDP.

  6. Synthesis and Characterization of Platinum(II) Complexes with Various Substituted 2,2'-Bipyridine Ligands.

    Science.gov (United States)

    Son, Seokhwan; Lee, Hwan Gyu; Lee, Nopl; Ryu, Minwoo; Kwak, Cheenhun; Lee, Jihoon; Ahn, Hogeun; Chung, Minchu

    2016-02-01

    The reaction of platinum 5,5"-(9,9-dioctyl-9H-fluorene-2,7-diyl)di-2,2'-bipyridine with 2,2'-bipyridine) PtCI2, (1,10-phenanthroline)PtC2 and (2,2'-bipyrimidine)PtC2: (2,2'-bipyridine)Pt[5,5"-(9,9-dioctyl-9H- fluorene-2,7-diyl)di-2,2'-bipyridine] (1) (2,2'-bipyrimi-dine)Pt[5,5"-(9,9-dioctyl-9H-fluorene-2,7-diyl)di- 2,2'-bipyridine] (2) (1,10-Phenantroline)-Pt[5,5"-(9,9-dioctyl-9H-fluorene-2,7-diyl)di-2,2'-bipyridine] (3). In the study, new platinum complex compounds were synthesized utilizing the ligand of a 5,5"-(9,9- dioctyl-9H-fluorene-2,7-diyl)di-2,2'-bipyridine). Each of the three complexes was obtained through the reaction carried out in this study. These complexes were analyzed using 1H(13C)-NMR, PL, and a UV-vis spectrophotometer. The maximum wavelengths of complexes 1, 2, and 3 appear at 519 nm, 375 nm, and 517 nm, respectively. The quantum yields of these complexes are in the range of 0.35-0.67.

  7. Thermal decomposition of vinyl- and allylsilane platinum(II complexes and platinum(II catalysed synthesis of (E,(E-1,4-diphenyl-1,3-butadiene

    Directory of Open Access Journals (Sweden)

    Paul P. Mebe

    2008-12-01

    Full Text Available Thermal stabilities of Pt(II complexes: K[PtCl3(CH2=CHSiMe3], K[PtCl3(CH2=CHCH2SiMe3], K[(acacPtCl(CH2=CHSiMe3] and [PtCl(CH2=CHCH2SiMe3]2, were examined. All complexes were found to be stable at room temperature but they decomposed without melting above about 90 oC. The allylsilane complex decomposed above about 125 oE,(E-1,4-diphenyl-1,3-butadiene was stereoselectively synthesised in good yield from (E-β-styrylsilane in the presence of Zeise’s salt.

  8. A highly sensitive amperometric sensor for oxygen based on iron(II) tetrasulfonated phthalocyanine and iron(III) tetra-(N-methyl-pyridyl)-porphyrin multilayers

    International Nuclear Information System (INIS)

    Duarte, Juliana C.; Luz, Rita C.S.; Damos, Flavio S.; Tanaka, Auro A.; Kubota, Lauro T.

    2008-01-01

    The development of a highly sensitive sensor for oxygen is proposed using a glassy carbon (GC) electrode modified with alternated layers of iron(II) tetrasulfonated phthalocyanine (FeTsPc) and iron(III) tetra-(N-methyl-pyridyl)-porphyrin (FeT4MPyP). The modified electrode showed excellent catalytic activity for the oxygen reduction. The reduction potential of the oxygen was shifted about 330 mV toward less negative values with this modified electrode, presenting a peak current much higher than those observed on a bare GC electrode. Cyclic voltammetry and rotating disk electrode (RDE) experiments indicated that the oxygen reduction reaction involves 4 electrons with a heterogenous rate constant (k obs ) of 3 x 10 5 mol -1 L s -1 . A linear response range from 0.2 up to 6.4 mg L -1 , with a sensitivity of 4.12 μA L mg -1 (or 20.65 μA cm -2 L mg -1 ) and a detection limit of 0.06 mg L -1 were obtained with this sensor. The repeatability of the proposed sensor, evaluated in terms of relative standard deviation (R.S.D.) was 2.0% for 10 measurements of a solution of 6.4 mg L -1 oxygen. The sensor was applied to determine oxygen in pond and tap water samples showing to be a promising tool for this purpose

  9. The photodynamic and non-photodynamic actions of porphyrins

    Directory of Open Access Journals (Sweden)

    S.G. Afonso

    1999-03-01

    Full Text Available Porphyrias are a family of inherited diseases, each associated with a partial defect in one of the enzymes of the heme biosynthetic pathway. In six of the eight porphyrias described, the main clinical manifestation is skin photosensitivity brought about by the action of light on porphyrins, which are deposited in the upper epidermal layer of the skin. Porphyrins absorb light energy intensively in the UV region, and to a lesser extent in the long visible bands, resulting in transitions to excited electronic states. The excited porphyrin may react directly with biological structures (type I reactions or with molecular oxygen, generating excited singlet oxygen (type II reactions. Besides this well-known photodynamic action of porphyrins, a novel light-independent effect of porphyrins has been described. Irradiation of enzymes in the presence of porphyrins mainly induces type I reactions, although type II reactions could also occur, further increasing the direct non-photodynamic effect of porphyrins on proteins and macromolecules. Conformational changes of protein structure are induced by porphyrins in the dark or under UV light, resulting in reduced enzyme activity and increased proteolytic susceptibility. The effect of porphyrins depends not only on their physico-chemical properties but also on the specific site on the protein on which they act. Porphyrin action alters the functionality of the enzymes of the heme biosynthetic pathway exacerbating the metabolic deficiencies in porphyrias. Light energy absorption by porphyrins results in the generation of oxygen reactive species, overcoming the protective cellular mechanisms and leading to molecular, cell and tissue damage, thus amplifying the porphyric picture.

  10. Comparative Study on the Efficiency of the Photodynamic Inactivation of Candida albicans Using CdTe Quantum Dots, Zn(II Porphyrin and Their Conjugates as Photosensitizers

    Directory of Open Access Journals (Sweden)

    Osnir S. Viana

    2015-05-01

    Full Text Available The application of fluorescent II-VI semiconductor quantum dots (QDs as active photosensitizers in photodymanic inactivation (PDI is still being evaluated. In the present study, we prepared 3 nm size CdTe QDs coated with mercaptosuccinic acid and conjugated them electrostatically with Zn(II meso-tetrakis (N-ethyl-2-pyridinium-2-yl porphyrin (ZnTE-2-PyP or ZnP, thus producing QDs-ZnP conjugates. We evaluated the capability of the systems, bare QDs and conjugates, to produce reactive oxygen species (ROS and applied them in photodynamic inactivation in cultures of Candida albicans by irradiating the QDs and testing the hypothesis of a possible combined contribution of the PDI action. Tests of in vitro cytotoxicity and phototoxicity in fibroblasts were also performed in the presence and absence of light irradiation. The overall results showed an efficient ROS production for all tested systems and a low cytotoxicity (cell viability >90% in the absence of radiation. Fibroblasts incubated with the QDs-ZnP and subjected to irradiation showed a higher cytotoxicity (cell viability <90% depending on QD concentration compared to the bare groups. The PDI effects of bare CdTe QD on Candida albicans demonstrated a lower reduction of the cell viability (~1 log10 compared to bare ZnP which showed a high microbicidal activity (~3 log10 when photoactivated. The QD-ZnP conjugates also showed reduced photodynamic activity against C. albicans compared to bare ZnP and we suggest that the conjugation with QDs prevents the transmembrane cellular uptake of the ZnP molecules, reducing their photoactivity.

  11. A comparison of DNA binding profiles of dinuclear platinum compounds with polyamine linkers and the trinuclear platinum phase II clinical agent BBR3464

    Czech Academy of Sciences Publication Activity Database

    McGregor, T. D.; Hegmans, A.; Kašpárková, Jana; Neplechová, Kamila; Nováková, Olga; Peňázová, Hana; Vrána, Oldřich; Brabec, Viktor; Farrel, N.

    2002-01-01

    Roč. 7, 4/5 (2002), s. 397-404 ISSN 0949-8257 R&D Projects: GA ČR GA305/99/0695; GA ČR GA301/00/0556; GA ČR GA301/98/P231; GA AV ČR IAA5004101; GA AV ČR IAA7004805 Institutional research plan: CEZ:AV0Z5004920 Keywords : unwinding * dinuclear platinum * hydrogen bonding Subject RIV: BO - Biophysics Impact factor: 3.911, year: 2002

  12. Half-Lantern Pt(II and Pt(III Complexes. New Cyclometalated Platinum Derivatives

    Directory of Open Access Journals (Sweden)

    Violeta Sicilia

    2014-08-01

    Full Text Available The divalent complex [{Pt(bzq(μ-L}2] (1 [Hbzq = benzo[h]quinolone, HL = CF3C4H2N2SH: 4-(trifluoromethylpyrimidine-2-thiol] was obtained from equimolar amounts of [Pt(bzq(NCMe2]ClO4 and 4-(trifluoromethylpyrimidine-2-thiol with an excess of NEt3. The presence of a low intensity absorption band at 486 nm (CH2Cl2, assignable to a metal-metal-to-ligand charge transfer transition (1MMLCT [dσ*(Pt2→π*(bzq], is indicative of the existence of two platinum centers located in close proximity because the rigidity of the half-lantern structure allows the preservation of these interactions in solution. Compound 1 undergoes two-electron oxidation upon treatment with halogens X2 (X2: Cl2, Br2 or I2 to give the corresponding dihalodiplatinum (III complexes [{Pt(bzq(μ-LX}2] (L = CF3C4H2N2S-κN,S; X: Cl 2, Br 3, I 4. Complexes 2–4 were also obtained by reaction of 1 with HX (molar ratio 1:2, 10% excess of HX in THF with yields of about 80% and compound 2 was also obtained by reaction of [{Pt(bzq(μ-Cl}2] with HL (4-(trifluoromethylpyrimidine-2-thiol in molar ratio 1:2 in THF, although in small yield. The X-ray structures of 2 and 3 confirmed the half-lantern structure and the anti configuration of the molecules. Both of them show Pt–Pt distances (2.61188(15 Å 2, 2.61767(16 Å 3 in the low range of those observed in Pt2(III,IIIX2 half-lantern complexes.

  13. Soluble porphyrin polymers

    Science.gov (United States)

    Gust, Jr., John Devens; Liddell, Paul Anthony

    2015-07-07

    Porphyrin polymers of Structure 1, where n is an integer (e.g., 1, 2, 3, 4, 5, or greater) ##STR00001## are synthesized by the method shown in FIGS. 2A and 2B. The porphyrin polymers of Structure 1 are soluble in organic solvents such as 2-MeTHF and the like, and can be synthesized in bulk (i.e., in processes other than electropolymerization). These porphyrin polymers have long excited state lifetimes, making the material suitable as an organic semiconductor for organic electronic devices including transistors and memories, as well as solar cells, sensors, light-emitting devices, and other opto-electronic devices.

  14. Vibrational bands of luminescent zinc(II)-octaethyl-porphyrin using a polarization-sensitive 'microcopic' multiplex CARS technique

    NARCIS (Netherlands)

    Otto, Cornelis; Voroshilov, A.; Voroshilov, Artemy; Kruglik, S.; Kruglik, S.G.; Greve, Jan

    2001-01-01

    Polarization-sensitive, multiplex coherent anti-Stokes Raman scattering (ps-MCARS) has been used to detect the vibrational bands of the highly luminescent zinc(II)-octaethylporphyrin (Zn-OEP). We show here that ps-MCARS can be used to measure the vibrational bands under resonant conditions.

  15. A bioaccumulative cyclometalated platinum(II) complex with two-photon-induced emission for live cell imaging.

    Science.gov (United States)

    Koo, Chi-Kin; Wong, Ka-Leung; Man, Cornelia Wing-Yin; Lam, Yun-Wah; So, Leo King-Yan; Tam, Hoi-Lam; Tsao, Sai-Wah; Cheah, Kok-Wai; Lau, Kai-Chung; Yang, Yang-Yi; Chen, Jin-Can; Lam, Michael Hon-Wah

    2009-02-02

    The cyclometalated platinum(II) complex [Pt(L)Cl], where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine containing C(phenyl), N(pyridyl), and N(pyrazolyl) donor moieties, was found to possess two-photon-induced luminescent properties. The two-photon-absorption cross section of the complex in N,N-dimethylformamide at room temperature was measured to be 20.8 GM. Upon two-photon excitation at 730 nm from a Ti:sapphire laser, bright-green emission was observed. Besides its two-photon-induced luminescent properties, [Pt(L)Cl] was able to be rapidly accumulated in live HeLa and NIH3T3 cells. The two-photon-induced luminescence of the complex was retained after live cell internalization and can be observed by two-photon confocal microscopy. Its bioaccumulation properties enabled time-lapse imaging of the internalization process of the dye into living cells. Cytotoxicity of [Pt(L)Cl] to both tested cell lines was low, according to MTT assays, even at loadings as high as 20 times the dose concentration for imaging for 6 h.

  16. Synthesis, Characterization and in Vitro Antitumor Activity of Platinum(II Oxalato Complexes Involving 7-Azaindole Derivatives as Coligands

    Directory of Open Access Journals (Sweden)

    Pavel Štarha

    2014-07-01

    Full Text Available The platinum(II oxalato complexes [Pt(ox(naza2] (1–3 were synthesized and characterized by elemental analysis (C, H, N, multinuclear NMR spectroscopy (1H, 13C, 15N, 195Pt and electrospray ionization mass spectrometry (ESI-MS; naza = 4-chloro-7-azaindole (4Claza; 1, 3-bromo-7-azaindole (3Braza; 2 or 4-bromo-7-azaindole (4Braza; 3. The prepared substances were screened for their in vitro antitumor activity on the osteosarcoma (HOS and breast adenocarcinoma (MCF7 human cancer cell lines, where 2 showed moderate antitumor effect (IC50 = 27.5 μM, and 18.3 μM, respectively. The complex 2 was further tested on a panel of six others human cancer cell lines, including the malignant melanoma (G361, cervix carcinoma (HeLa, ovarian carcinoma (A2780, cisplatin-resistant ovarian carcinoma (A2780R, lung carcinoma (A549 and prostate adenocarcinoma (LNCaP. This substance was found to be moderate antitumor effective against G361 (IC50 = 17.3 μM, HeLa (IC50 = 31.8 μM and A2780 (IC50 = 19.2 μM cell lines. The complex 2 was also studied by NMR for its solution stability and by ESI-MS experiments for its ability to interact with biomolecules, such as cysteine, glutathione or guanosine 5'-monophosphate.

  17. How do ligands influence the quantum yields of cyclometalated platinum(ii) complexes, a theoretical research study.

    Science.gov (United States)

    Yang, Baozhu; Huang, Shuang; Wang, Jianhao

    2017-08-30

    A series of cyclometalated platinum(ii) complexes have been investigated with the TDDFT method. These complexes have similar structures but distinct phosphorescence quantum yields. Theoretical calculations were carried out to explain the differences in quantum yields from the conjugation effect of the cyclometalated ligand, molecular rigidity and ligand-field strength of the monodentate ligand. The radiative decay rate constants (k r ) have been discussed with the oscillator strength (f n ), the strength of the spin-orbit coupling (SOC) interaction between the lowest energy triplet excited state (T 1 ) and singlet excited states (S n ), and the energy gaps between E(T 1 ) and E(S n ). To illustrate the nonradiative decay processes, the transition states (TS) between the triplet metal-centered state ( 3 MC) and T 1 states have been optimized. In addition, the minimum energy crossing points (MECPs) between 3 MC and the ground states (S 0 ) were optimized. Finally, the potential energy curves along the nonradiative decay pathways are simulated. To obtain a phosphorescent complex with a high quantum yield, the complex should retain molecular rigidity well in the S 1 and T 1 states, while showing significant structural distortion at the MECP structure.

  18. Synthesis and photoinduced electron transfer in platinum(II) bis(N-(4-ethynylphenyl)carbazole)bipyridine fullerene complexes.

    Science.gov (United States)

    Lee, Sai-Ho; Chan, Chris Tsz-Leung; Wong, Keith Man-Chung; Lam, Wai Han; Kwok, Wai-Ming; Yam, Vivian Wing-Wah

    2014-12-21

    Platinum(ii) bis(N-(4-ethynylphenyl)carbazole)bipyridine fullerene complexes, (Cbz)2-Pt(bpy)-C60 and ((t)BuCbz)2-Pt(bpy)-C60, were synthesized. Their photophysical properties were studied by electronic absorption and emission spectroscopy and the origin of the transitions was supported by computational studies. The electrochemical properties were also studied and the free energies for charge-separation and charge-recombination processes were evaluated. The photoinduced electron transfer reactions in the triads were investigated by femtosecond and nanosecond transient absorption spectroscopy. In dichloromethane, both triads undergo ultrafast charge separation from the (3)MLCT/LLCT excited state within 300 fs to yield their respective triplet charge-separated (CS) states, namely (Cbz)2˙(+)-Pt(bpy)-C60˙(-) and ((t)BuCbz)2˙(+)-Pt(bpy)-C60˙(-), and the CS states would undergo charge recombination to give the (3)C60* state, which subsequently decays to the ground state in 22-28 μs.

  19. Dichlorido[N-(N,N-dimethylcarbamimidoyl-N′,N′,4-trimethylbenzohydrazonamide]platinum(II nitromethane hemisolvate

    Directory of Open Access Journals (Sweden)

    Dmitrii S. Bolotin

    2014-04-01

    Full Text Available In the title compound, [PtCl2(C13H21N5]·0.5CH3NO2, the PtII atom is coordinated in a slightly distorted square-planar geometry by two Cl atoms and two N atoms of the bidentate ligand. The (1,3,5-triazapentadienePtII metalla ring is slightly bent and does not conjugate with the aromatic ring. In the crystal, N—H...Cl hydrogen bonds link the complex molecules, forming chains along [001]. The nitromethane solvent molecule shows half-occupancy and is disordered over two sets of sites about an inversion centre.

  20. Porphyrins - blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003372.htm Porphyrins blood test To use the sharing features on this page, ... blood or the urine . This article discusses the blood test. How the Test is Performed A blood sample ...

  1. Dimensional Control and Morphological Transformations of Supramolecular Polymeric Nanofibers Based on Cofacially-Stacked Planar Amphiphilic Platinum(II) Complexes.

    Science.gov (United States)

    Robinson, Matthew E; Nazemi, Ali; Lunn, David J; Hayward, Dominic W; Boott, Charlotte E; Hsiao, Ming-Siao; Harniman, Robert L; Davis, Sean A; Whittell, George R; Richardson, Robert M; De Cola, Luisa; Manners, Ian

    2017-09-26

    Square-planar platinum(II) complexes often stack cofacially to yield supramolecular fiber-like structures with interesting photophysical properties. However, control over fiber dimensions and the resulting colloidal stability is limited. We report the self-assembly of amphiphilic Pt(II) complexes with solubilizing ancillary ligands based on polyethylene glycol [PEG n , where n = 16, 12, 7]. The complex with the longest solubilizing PEG ligand, Pt-PEG 16 , self-assembled to form polydisperse one-dimensional (1D) nanofibers (diameters fibers of length up to ca. 400 nm. The fiber lengths were dependent on the Pt-PEG 16 complex to seed mass ratio in a manner analogous to a living covalent polymerization of molecular monomers. Moreover, the fiber lengths were unchanged in solution after 1 week and were therefore "static" with respect to interfiber exchange processes on this time scale. In contrast, similarly formed near-uniform fibers of Pt-PEG 12 exhibited dynamic behavior that led to broadening of the length distribution within 48 h. After aging for 4 weeks in solution, Pt-PEG 12 fibers partially evolved into 2D platelets. Furthermore, self-assembly of Pt-PEG 7 yielded only transient fibers which rapidly evolved into 2D platelets. On addition of further fiber-forming Pt complex (Pt-PEG 16 ), the platelets formed assemblies via the growth of fibers selectively from their short edges. Our studies demonstrate that when interfiber dynamic exchange is suppressed, dimensional control and hierarchical structure formation are possible for supramolecular polymers through the use of kinetically controlled seeded growth methods.

  2. Photoactive platinum(II) complexes of nonsteroidal anti-inflammatory drug naproxen: Interaction with biological targets, antioxidant activity and cytotoxicity.

    Science.gov (United States)

    Srivastava, Payal; Singh, Khushbu; Verma, Madhu; Sivakumar, Sri; Patra, Ashis K

    2018-01-20

    The effect on the therapeutic efficacy of Pt(II) complexes on combining non-steroidal anti-inflammatory drugs (NSAIDs) is an attractive strategy to circumvent chronic inflammation mediated by cancer and metastasis. Two square-planar platinum(II) complexes: [Pt(dach)(nap)Cl] (1) and [Pt(dach)(nap) 2 ] (2), where dach = (1R,2R)-dichloro(cyclohexane-1,2-diamine) and NSAID drug naproxen (nap), have been designed for studying their biological activity. The naproxen bound to the Pt(II) centre get released upon photoirradiation with low-power UV-A light as confirmed by the significant enhancement in emission intensities of the complexes. The compounds were evaluated for their photophysical properties, photostability, reactivity with 5'-guanosine monophophosphate (5'-GMP), interactions with CT-DNA and BSA, antioxidant activity and reactive oxygen species mediated photo-induced DNA damage properties. ESI-MS studies demonstrated the formation of bis-adduct with 5'-GMP and the formation of Pt II -DNA crosslinks by gel electrophoretic mobility shift assay and ITC studies. The interaction of the complexes 1 and 2 with the CT-DNA exhibits potential binding affinity (K b  ∼ 10 4  M -1 , K app ∼ 10 5  M -1 ), implying intercalation to CT-DNA through planar naphthyl ring of the complexes. Both the complexes also exhibit strong binding affinity towards BSA (K BSA ∼ 10 5  M -1 ). The complexes exhibit efficient DNA damage activity on irradiation at 365 nm via formation of singlet oxygen ( 1 O 2 ) and hydroxyl radical ( • OH) under physiological conditions. Both the complexes were cytotoxic in dark and exhibit significant enhancement of cytotoxicity upon photo-exposure against HeLa and HepG2 cancer cells giving IC 50 values ranging from 8 to 12 μM for 1 and 2. The cellular internalization data showed cytosolic and nuclear localization of the complexes in the HeLa cells. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Photosensitization of liposomes by porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Grossweiner, L I; Goyal, G C

    1984-01-01

    Lipid peroxidation was photosensitized in egg phosphatidylcholine (EPC) liposomes by hematoporphyrin (HP), hematoporphyrin derivative (HpD) and uroporphyrin I (Uro-I). Photosensitization by HP was type II via singlet oxygen (/sup 1/O/sub 2/) for the monomeric and dimeric states and type I for aggregated HP. Uro-I was an efficient type II /sup 1/O/sub 2/ photosensitizer. The HpD fraction enriched in the active biological component (HpD-A) was a type II /sup 1/O/sub 2/ photosensitizer at high and low concentrations. The spectral differences between HpD-A in buffer and solubilized in small EPC liposomes are attributed to a conformation change of a key dimer constituent from a folded to a planar geometry. The implications of the results for the action mechanism in photoradiation therapy of tumors with these porphyrins are discussed. 73 references, 1 figure, 5 tables.

  4. trans-Dichlorido­bis(3,4-dimethyl­pyridine)platinum(II)

    Science.gov (United States)

    Chernyshev, Alexander N.; Bokach, Nadezhda A.; Izotova, Youlia A.; Haukka, Matti

    2009-01-01

    In the title compound, trans-[PtCl2(C7H9N)2], the PtII atom is located on an inversion center and is coordinated by two 3,4-dimethyl­pyridine ligands and two chloride ligands, resulting in a typical slightly distorted square-planar geometry. The crystallographic inversion centre forces the value of the C—N—N—C torsion angle to be linear and the 3,4-dimethyl-pyridine ligands to be coplanar. PMID:21581530

  5. Oxidative Reactivity and Cytotoxic Properties of a Platinum(II) Complex Prepared by Outer-Sphere Amide Bond Coupling

    Science.gov (United States)

    Wilson, Justin J.; Lippard, Stephen J.

    2012-01-01

    Benzyl amine was coupled to the dangling carboxylic acid groups of the platinum(II) complex [Pt(edda)Cl2], where edda = ethylenediamine-N,N’-diacetic acid, to give the diamidetethered complex [Pt(L)Cl2] (1), where L = ethylenediamine-N,N’-bis(N-benzylacetamide). Complex 1 was oxidized with both PhICl2 and Br2. Oxidation with PhICl2 cleanly afforded the tetrachloride complex, [Pt(L)Cl4] (2), whereas oxidation with Br2 gave rise to several mixed halide complexes of the general formula, [Pt(L)ClxBr4-x], where x = 1, 2, or 3. Complexes 1 and 2 were fully characterized by 1H, 13C, and 195Pt NMR spectroscopy, as well as by ESI-MS. These compounds exist as a mixture of diastereomers that arise from the chirality of the two coordinated nitrogen atoms. Crystal structures of 1, 2, and [Pt(L)ClxBry] (3) are reported. Although refined as the tetrabromide complex [Pt(L)Br4], the crystal structure of 3 is a mixture of species with site-occupancy disorder of chloride and bromide ligands. DFT calculations indicate that the two sets of diastereomers of 1 and 2 are effectively thermoneutral, a conclusion that is also supported by the observation of both members of each pair by NMR spectroscopy. The cytotoxicity of 1 and 2 was measured by the MTT assay in HeLa cells and compared to that of cisplatin. Both exhibit IC50 values close to 50 μM and are therefore substantially less toxic than cisplatin, for which the IC50 is 1 μM. PMID:24489429

  6. Trans- and cis-2-phenylindole platinum(II) complexes as cytotoxic agents against human breast adenocarcinoma cell lines

    Science.gov (United States)

    Tomé, Maria; López, Concepción; González, Asensio; Ozay, Bahadir; Quirante, Josefina; Font-Bardía, Mercè; Calvet, Teresa; Calvis, Carme; Messeguer, Ramon; Baldomá, Laura; Badía, Josefa

    2013-09-01

    The synthesis and characterization of the new 2-phenylindole derivative: C8H3N-2-C6H5-3NOMe-5OMe (3c) and the trans- and cis-isomers of [Pt(3c)Cl2(DMSO)] complexes (4c and 5c, respectively) are described. The crystal structures of 4c·CH2Cl2 and 5c confirm: (a) the existence of a Pt-Nindole bond, (b) the relative arrangement of the Cl- ligands [trans- (in 4c) or cis- (in 5c)] and (c) the anti-(E) configuration of the oxime. The cytotoxic assessment of C8H3N-2-(C6H4-4‧R1)-3NOMe-5R2 [with R1 = R2 = H (3a); R1 = Cl, R2 = H (3b) and R1 = H, R2 = OMe (3c)] and the geometrical isomers of [Pt(L)Cl2(DMSO)] with L = 3a-3c [trans- (4a-4c) and cis- (5a-5c), respectively] against human breast adenocarcinoma cell lines (MDA-MB231 and MCF-7) is also reported and reveals that all the platinum(II) complexes (except 4a) are more cytotoxic than cisplatin in front of the MCF7 cell line. Electrophoretic DNA migration studies of the synthesized compounds in the absence and in the presence of topoisomerase-I have been performed, in order to get further insights into their mechanism of action.

  7. Design, synthesis and anticancer activity of diam(m)ine platinum(II) complexes bearing a small-molecular cell apoptosis inducer dichloroacetate.

    Science.gov (United States)

    Liu, Weiping; Jiang, Jing; Xu, Yongping; Hou, Shuqian; Sun, Liping; Ye, Qingsong; Lou, Liguang

    2015-05-01

    Four new diam(m)ine platinum complexes containing the dichloroacetate moiety in 3-dichoroacetoxylcyclobutane-1,1-dicarboxylate as the leaving group were synthesized, characterized by elemental analysis as well as by ESI(+)-MS (electrospray ionization mass spectrometry in positive mode), FT-IR, (1)H- and (13)C-NMR, and evaluated for their in vitro anticancer activity against human lung cancer cell line (A549) and ovarian cancer cell lines (SK-OV-3, SK-OV-3/DDP). Diam(m)ines used in the present study belong to the carriers of six clinically approved platinum drugs. Among the complexes synthesized, complex 2, cis-[Pt(II)(1R,2R-diaminocyclohexane)·(3-dichoroacetoxylcyclobutane-1,1-dicarboxylate)] is the most promising in terms of water solubility and potential of being totally devoid of cross-drug resistance with cisplatin. Therefore, complex 2 was selected for the dichloroacetate release test. The test shows dichloroacetate can be efficiently released from complex 2 under physiological conditions via the hydrolysis of an ester bond bridging the dichloroacetate moiety and platinum pharmacophores together. Our study supports the further evaluation of this complex as a drug candidate. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. bis-Nitrile and bis-Dialkylcyanamide Platinum(II) Complexes as Efficient Catalysts for Hydrosilylation Cross-Linking of Siloxane Polymers.

    Science.gov (United States)

    Islamova, Regina M; Dobrynin, Mikhail V; Ivanov, Daniil M; Vlasov, Andrey V; Kaganova, Elena V; Grigoryan, Galina V; Kukushkin, Vadim Yu

    2016-03-05

    cis- and trans-Isomers of the platinum(II) nitrile complexes [PtCl2(NCR)2] (R = NMe2, N(C₅H10), Ph, CH2Ph) were examined as catalysts for hydrosilylation cross-linking of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated poly(dimethylsiloxane-co-ethylhydrosiloxane) producing high quality silicone rubbers. Among the tested platinum species the cis-complexes are much more active catalysts than their trans-congeners and for all studied platinum complexes cis-[PtCl2(NCCH2Ph)2] exhibits the best catalytic activity (room temperature, c = 1.0 × 10(-4) mol/L, τpot-life 60 min, τcuring 6 h). Although cis-[PtCl₂(NCCH2Ph)2] is less active than the widely used Karstedt's catalyst, its application for the cross-linking can be performed not only at room temperature (c = 1.0 × 10(-4) mol/L), but also, more efficiently, at 80 °C (c = 1.0 × 10(-4)-1.0 × 10(-5) mol/L) and it prevents adherence of the formed silicone rubbers to equipment. The usage of the cis- and trans-[PtCl2(NCR)2] complexes as the hydrosilylation catalysts do not require any inhibitors and, moreover, the complexes and their mixtures with vinyl- and trimethylsilyl terminated polysiloxanes are shelf-stable in air. Tested catalysts do not form colloid platinum particles after the cross-linking.

  9. Copper (II) complexes of bidentate ligands exhibit potent anti-cancer activity regardless of platinum sensitivity status.

    Science.gov (United States)

    Wehbe, Mohamed; Lo, Cody; Leung, Ada W Y; Dragowska, Wieslawa H; Ryan, Gemma M; Bally, Marcel B

    2017-12-01

    Insensitivity to platinum, either through inherent or acquired resistance, is a major clinical problem in the treatment of many solid tumors. Here, we explored the therapeutic potential of diethyldithiocarbamate (DDC), pyrithione (Pyr), plumbagin (Plum), 8-hydroxyquinoline (8-HQ), clioquinol (CQ) copper complexes in a panel of cancer cell lines that differ in their sensitivity to platins (cisplatin/carboplatin) using a high-content imaging system. Our data suggest that the copper complexes were effective against both platinum sensitive (IC 50  ~ 1 μM platinum) and insensitive (IC 50  > 5 μM platinum) cell lines. Furthermore, copper complexes of DDC, Pyr and 8-HQ had greater therapeutic activity compared to the copper-free ligands in all cell lines; whereas the copper-dependent activities of Plum and CQ were cell-line specific. Four of the copper complexes (Cu(DDC) 2 , Cu(Pyr) 2 , Cu(Plum) 2 and Cu(8-HQ) 2 ) showed IC 50 values less than that of cisplatin in all tested cell lines. The complex copper DDC (Cu(DDC) 2 ) was selected for in vivo evaluation due to its low nano-molar range activity in vitro and the availability of an injectable liposomal formulation. Liposomal (Cu(DDC) 2 ) was tested in a fast-growing platinum-resistant A2780-CP ovarian xenograft model and was found to achieve a statistically significant reduction (50%; p < 0.05) in tumour size. This work supports the potential use of copper-based therapeutics to treat cancers that are insensitive to platinum drugs.

  10. Highly Luminescent Dinuclear Platinum(II) Complexes Incorporating Bis-Cyclometallating Pyrazine-Based Ligands: A Versatile Approach to Efficient Red Phosphors

    OpenAIRE

    Culham, Stacey; Lanoe, Pierre-Henri; Whittle, Victoria; Durrant, Marcus; Williams, Gareth; Kozhevnikov, Valery

    2013-01-01

    A series of luminescent dinuclear platinum(II) complexes incorporating diphenylpyrazine-based bridging ligands ((LH2)-H-n) has been prepared. Both 2,5-diphenylpyrazine ((LH2)-H-2) and 2,3-diphenylpyrazine ((LH2)-H-3) are able to undergo cyclometalation of the two phenyl rings, with each metal ion binding to the two nitrogen atoms of the central heterocycle, giving, after treatment with the anion of dipivaloyl methane (dpm), complexes of formula \\{Pt(dpm)\\}(2)L-n. These compounds are isomers o...

  11. Push-pull quinoidal porphyrins.

    Science.gov (United States)

    Smith, Martin J; Blake, Iain M; Clegg, William; Anderson, Harry L

    2018-05-01

    A family of push-pull quinoidal porphyrin monomers has been prepared from a meso-formyl porphyrin by bromination, thioacetal formation, palladium-catalyzed coupling with malononitrile and oxidation with DDQ. Attempts at extending this synthesis to a push-pull quinoidal/cumulenic porphyrin dimer were not successful. The crystal structures of the quinoidal porphyrins indicate that there is no significant contribution from singlet biradical or zwitterionic resonance forms. The crystal structure of an ethyne-linked porphyrin dimer shows that the torsion angle between the porphyrin units is only about 3°, in keeping with crystallographic results on related compounds, but contrasting with the torsion angle of about 35° predicted by computational studies. The free-base quinoidal porphyrin monomers form tightly π-stacked layer structures, despite their curved geometries and bulky aryl substituents.

  12. Platinum(II) complexes with steroidal esters of L-methionine and L-histidine: Synthesis, characterization and cytotoxic activity

    Czech Academy of Sciences Publication Activity Database

    Kvasnica, Miroslav; Buděšínský, Miloš; Swaczynová, Jana; Pouzar, Vladimír; Kohout, Ladislav

    2008-01-01

    Roč. 16, č. 7 (2008), s. 3704-3713 ISSN 0968-0896 R&D Projects: GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50380511 Keywords : steroids * platinum * L-histidin * L-methionin Subject RIV: CC - Organic Chemistry Impact factor: 3.075, year: 2008

  13. Phosphate buffer and salt medium concentrations affect the inactivation of T4 phage by platinum(II) complexes

    DEFF Research Database (Denmark)

    Pedersen, Henrik B.; Josephsen, Jens; Kerszman, Gustaw

    1985-01-01

    -Tris) buffer and HEPES buffer. The phosphate abolishes the antiphage activity of the platinum complexes probably by some sort of complex formation. This together with dimerization reactions qualitatively explains the tailing off of the phage inactivation rate. High concentrations of NaNO3 as the salt medium...

  14. Mechanistic insights into toxic effects of a benzotriazolate-bridged dinuclear platinum(II) compound in tumor cells

    Czech Academy of Sciences Publication Activity Database

    Olivová, R.; Štěpánková, Jana; Muchová, T.; Novohradský, V.; Nováková, Olga; Vrána, Oldřich; Kašpárková, Jana; Brabec, Viktor

    2012-01-01

    Roč. 393, DEC (2012), s. 204-211 ISSN 0020-1693 R&D Projects: GA ČR(CZ) GAP301/10/0598 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : Dinuclear platinum * Antitumor * DNA binding Subject RIV: BO - Biophysics Impact factor: 1.687, year: 2012

  15. Conformation and recognition of DNA damaged by antitumor cis-dichlorido platinum(II) complex of CDK inhibitor bohemine

    Czech Academy of Sciences Publication Activity Database

    Nováková, Olga; Lišková, Barbora; Vystrčilová, Jana; Suchánková, Tereza; Vrána, Oldřich; Starha, P.; Trávníček, Z.; Brabec, Viktor

    2014-01-01

    Roč. 78, MAY2014 (2014), s. 54-64 ISSN 0223-5234 R&D Projects: GA ČR(CZ) GA13-08273S Institutional support: RVO:68081707 Keywords : Antitumor * Platinum * DNA Subject RIV: BO - Biophysics Impact factor: 3.447, year: 2014

  16. Synthesis and reactivity towards diiodine of palladium(II) and platinum(II) complexes with non-cyclic and cyclic ligands (C6H3{CH=NR1R2}2-2,6)-. End-on diiodine-platinum(II) bonding in macrocyclic [PtI(C6H3{CH2NMe(CH2)7MeNCH2}-2,6)(h1-I2)

    NARCIS (Netherlands)

    Koten, G. van; Beek, J.A.M. van; Dekker, G.P.C.M.; Wissing, E.; Zoutberg, M.C.; Stam, C.H.

    1990-01-01

    Several new organo-platinum(II) and -palladium(II) complexes [MX(C{6}H{3}{CH{2}NR}1{R}2{}{2}-2, 6)] (X = halide, M = Pt, Pd; R}1{ = R}2{ = Et; R}2{ = Me, R}1{ = }t{Bu, M = Pt: R}2{ = Me, R}1{ = Ph) have been synthesized from [PtCl{2}(SEt{2}){2}] or [PdCl{2}(COD)] (COD = 1, 5-cyclooctadiene) by

  17. Synthetic Porphyrins and Metalloporphyrins

    Science.gov (United States)

    1976-12-10

    disease syndromes , drug metabolism and cancer. Porphyrins and metalloporphyrins such as tetraphenylporphine sulfonate and hema- toporphyrin have been found...267(1941). 34. A. D. Adler, F. R. Longo, J. D. Finarelli, J. Goldmacher, J. Assour and L. Korsakoff , J. Org. Chem., 32, 476(1967). 35. H. W

  18. A randomized phase II study of carboplatin plus pegylated liposomal doxorubicin versus carboplatin plus paclitaxel in platinum sensitive ovarian cancer patients: a Hellenic Cooperative Oncology Group study

    Directory of Open Access Journals (Sweden)

    Briasoulis Evangelos

    2010-01-01

    Full Text Available Abstract Background Platinum-based combinations are the standard second-line treatment for platinum-sensitive ovarian cancer (OC. This randomized phase II study was undertaken in order to compare the combination of carboplatin and pegylated liposomal doxorubicin (LD with carboplatin and paclitaxel (CP in this setting. Methods Patients with histologically confirmed recurrent OC, at the time of or more than 6 months after platinum-based chemotherapy, were randomized to six cycles of CP (carboplatin AUC5 + paclitaxel 175 mg/m2, d1q21 or CLD (carboplatin AUC5 + pegylated LD 45 mg/m2, d1q28. Results A total of 189 eligible patients (CP 96, CLD 93, with a median age of 63 years, median Performance Status (PS 0 and a median platinum free interval (PFI of 16.5 months, entered the study. Discontinuation due to toxicity was higher in the CP patients (13.5% versus 3%, P = 0.016. The overall response rate was similar: CP 58% versus CLD 51%, P = 0.309 (Complete Response; CR 34% versus 23% and there was no statistical difference in time-to-progression (TTP or overall survival (OS; TTP 10.8 months CP versus 11.8 CLD, P = 0.904; OS 29.4 months CP versus 24.7 CLD, P = 0.454. No toxic deaths were recorded. Neutropenia was the most commonly seen severe toxicity (CP 30% versus CLD 35%. More frequent in CLD were severe thrombocytopenia (11% versus 2%, P = 0.016, skin toxicity and Palmar-plantar erythrodysesthesia (PPE grade 1-2 (38% versus 9%, PP = 0.029, 20% versus 5%, P = 0.003. PS and PFI were independent prognostic factors for TTP and OS. Conclusions The combination of pegylated LD with carboplatin is effective, showing less neurotoxicity and alopecia than paclitaxel-carboplatin. It thus warrants a further phase III evaluation as an alternative treatment option for platinum-sensitive OC patients. Trial Registration Australian New Zealand Clinical Trials Registry: ACTRN12609000436279

  19. Improved recovery of trace amounts of gold (III), palladium (II) and platinum (IV) from large amounts of associated base metals using anion-exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, I. [Lab. of Chemistry, Tokyo Women' s Medical Univ. (Japan); Takeda, Y.; Ishida, K. [Lab. of Chemistry, Nippon Medical School, Kawasaki-shi, Kanagawa-ken (Japan)

    2000-02-01

    The adsorption and desorption behaviors of gold (III), palladium (II) and platinum (IV) were surveyed in column chromatographic systems consisting of one of the conventional anion-exchange resins of large ion-exchange capacity and dilute thiourea solutions. The noble metals were strongly adsorbed on the anion-exchange resins from dilute hydrochloric acid, while most base metals did not show any marked adsorbability. These facts made it possible to separate the noble metals from a large quantity of base metals such as Ag (I), Al (III), Co (II), Cu (II), Fe (III), Mn (II), Ni (II), Pb (II), and Zn (II). Although it used to be very difficult to desorb the noble metals from the resins used, the difficulty was easily overcome by use of dilute thiourea solutions as an eluant. In the present study, as little as 1.00 {mu}g of the respective noble metals was quantitatively separated and recovered from as much as ca. 10 mg of a number of metals on a small column by elution with a small amount of dilute thiourea solution. The present systems should be applicable to the separation, concentration and recovery of traces of the noble metals from a number of base metals coexisting in a more extended range of amounts and ratios. (orig.)

  20. The PACOVAR-trial: A phase I/II study of pazopanib (GW786034) and cyclophosphamide in patients with platinum-resistant recurrent, pre-treated ovarian cancer

    International Nuclear Information System (INIS)

    Eichbaum, Michael; Fersis, Nikos; Schmidt, Marcus; Wallwiener, Markus; Schneeweiss, Andreas; Sohn, Christof; Mayer, Christine; Eickhoff, Regina; Bischofs, Esther; Gebauer, Gerhard; Fehm, Tanja; Lenz, Florian; Fricke, Hans-Christian; Solomayer, Erich

    2011-01-01

    The prognosis of patients with recurrent, platinum-resistant epithelial ovarian cancer (EOC) is poor. There is no standard treatment available. Emerging evidence suggests a major role for antiangiogenic treatment modalities in EOC, in particular in combination with the metronomic application of low dose chemotherapy. The novel, investigational oral antiangiogenic agent pazopanib targeting vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR) and c-kit is currently being studied in different tumour types and is already used as first line therapy in recurrent renal cell carcinoma. A combined therapy consisting of pazopanib and metronomic oral cyclophosphamide may offer a well-tolerable treatment option to patients with recurrent, pretreated EOC. This study is designed as a multicenter phase I/II trial evaluating the optimal dose for pazopanib (phase I) as well as activity and tolerability of a combination regimen consisting of pazopanib and metronomic cyclophosphamide in the palliative treatment of patients with recurrent, platinum-resistant, pre-treated ovarian cancer (phase II). The patient population includes patients with histologically or cytologically confirmed diagnosis of EOC, cancer of the fallopian tube or peritoneal cancer which is platinumresistant or -refractory. Patients must have measurable disease according to RECIST criteria and must have failed available standard chemotherapy. Primary objectives are determination of the optimal doses for pazopanib (phase I) and the overall response rate according to RECIST criteria (phase II). Secondary objectives are time to progression, overall survival, safety and tolerability. The treatment duration is until disease progression or intolerability of study drug regimen (with a maximum of 13 cycles up to 52 weeks per subject). The current phase I/II trial shall clarify the potential of the multitargeting antiangiogenic tyrosinkinaseinhibitor GW 786034 (pazopanib) in

  1. Study of the interaction between two newly synthesized cyclometallated platinum (II) complexes and human serum albumin: Spectroscopic characterization and docking simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yousefi, Reza, E-mail: ryousefi@shirazu.ac.ir [Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Mohammadi, Roghayeh [Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Taheri-Kafrani, Asghar [Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Bagher Shahsavani, Mohammad [Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Dadkhah Aseman, Marzieh; Masoud Nabavizadeh, S.; Rashidi, Mehdi [Department of Chemistry, College of Sciences, Shiraz University, Shiraz (Iran, Islamic Republic of); Poursasan, Najmeh; Moosavi-Movahedi, Ali-Akbar [Institute of Biochemistry and Biophysics (IBB), the University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-03-15

    This study describes HSA binding properties of two cyclometalated platinum (II) complexes with non-leaving lipophilic ligands; deprotonated 2-phenylpyridine (ppy): C{sub 1} and deprotonated benzo [h]quinolone (bhq): C{sub 2}, using UV–vis, fluorescence and circular dichroism (CD) spectroscopy. The absorption spectra of HSA decreased in the presence of increasing concentration of these complexes, reflecting HSA structural alteration after drug's binding. Also the thermodynamic parameters (ΔG, ΔH and ΔS) that obtained from Trp fluorescence study revealed that the interaction between these complexes and HSA were spontaneous. In addition, C{sub 1} with flexible chemical structure indicated significantly higher fluorescence quenching and binding affinity to HSA than C{sub 2} which possesses a higher structural rigidity. The ANS fluorescence results also indicated that two Pt (II) complexes were competing for binding to the hydrophobic regions of HSA. Moreover, CD results demonstrated that C{sub 2} complex induced alteration of HSA conformation to more significant extent compared to C{sub 1}. The molecular docking results revealed the involvement of π–π stacking and hydrophobic interaction between these complexes and the protein. Overall, this study may highlight the significance of structural flexibility in designing of future anticancer Pt (II) complexes with improved binding affinity for HSA. - Highlights: • HSA is a general transport carrier for a wide variety of ligands such as metabolites and pharmaceutical drugs. • The HSA binding properties of two structurally related cyclometallated platinum (II) complexes (C{sub 1} and C{sub 2}) were studied. • The complexes can bind to HSA and induce structural alteration in this protein. • The thermodynamic parameters revealed that the interactions were spontaneous and mainly hydrophobic driven. • C{sub 1} with flexible chemical structure indicated a higher binding affinity for HSA than C{sub 2}.

  2. Synthesis, singlet-oxygen photogeneration, two-photon absorption, photo-induced DNA cleavage and cytotoxic properties of an amphiphilic β-Schiff-base linked Ru(II) polypyridyl–porphyrin conjugate

    International Nuclear Information System (INIS)

    Ke, Hanzhong; Ma, Wanpeng; Wang, Hongda; Cheng, Guoe; Yuan, Han; Wong, Wai-Kwok; Kwong, Daniel W.J.; Tam, Hoi-Lam; Cheah, Kok-Wai; Chan, Chi-Fai; Wong, Ka-Leung

    2014-01-01

    A novel porphyrin–polypyridyl ruthenium(II) conjugate (TPP–Ru), in which the ruthenium(II) polypyridyl moiety is linked to the β-position of the tetraphenylporphyrin via a Schiff base linkage, has been synthesized and characterized by 1 H NMR, HRMS and UV–visible spectroscopy. The relative singlet oxygen quantum yield and two-photon absorption cross-section of this conjugate, together with its photo-induced DNA cleavage and cytotoxic activities were measured. The results show that the amphiphilic ruthenium(II) polypyridyl–porphyrin conjugate is an effective DNA photocleavage agent, with potential application in one- and two-photon absorption anti-cancer photodynamic therapy. - Highlights: • New porphyrin–ruthenium(II) polypyridyl complexes (TTP–Ru) have been synthesized. • The TTP–Ru shows substantial two-photon absorption cross-section (σ 2 =391 GM). • The TTP–Ru exhibits a substantial 1 O 2 quantum yield (0.64±0.13). • The TTP–Ru exhibits a strong DNA cleavage activity upon photo-excitation. • The TTP–Ru is available for in vitro imaging and as a photodynamic therapy agent

  3. Synthesis, singlet-oxygen photogeneration, two-photon absorption, photo-induced DNA cleavage and cytotoxic properties of an amphiphilic β-Schiff-base linked Ru(II) polypyridyl–porphyrin conjugate

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Hanzhong, E-mail: kehanz@163.com [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan, Hubei 430074 (China); Ma, Wanpeng; Wang, Hongda; Cheng, Guoe [Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan, Hubei 430074 (China); Yuan, Han [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Wong, Wai-Kwok, E-mail: wkwong@hkbu.edu.hk [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Institute of Advanced Materials, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Kwong, Daniel W.J. [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Tam, Hoi-Lam; Cheah, Kok-Wai [Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Institute of Advanced Materials, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China); Chan, Chi-Fai; Wong, Ka-Leung [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR (China)

    2014-10-15

    A novel porphyrin–polypyridyl ruthenium(II) conjugate (TPP–Ru), in which the ruthenium(II) polypyridyl moiety is linked to the β-position of the tetraphenylporphyrin via a Schiff base linkage, has been synthesized and characterized by {sup 1}H NMR, HRMS and UV–visible spectroscopy. The relative singlet oxygen quantum yield and two-photon absorption cross-section of this conjugate, together with its photo-induced DNA cleavage and cytotoxic activities were measured. The results show that the amphiphilic ruthenium(II) polypyridyl–porphyrin conjugate is an effective DNA photocleavage agent, with potential application in one- and two-photon absorption anti-cancer photodynamic therapy. - Highlights: • New porphyrin–ruthenium(II) polypyridyl complexes (TTP–Ru) have been synthesized. • The TTP–Ru shows substantial two-photon absorption cross-section (σ{sub 2}=391 GM). • The TTP–Ru exhibits a substantial {sup 1}O{sub 2} quantum yield (0.64±0.13). • The TTP–Ru exhibits a strong DNA cleavage activity upon photo-excitation. • The TTP–Ru is available for in vitro imaging and as a photodynamic therapy agent.

  4. Antibatic photovoltaic response in zinc-porphyrin-liked oligothiophenes

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Spanggaard, H.

    2005-01-01

    -stannylchloride and subsequent palladium catalysed Stille coupling. We further synthesised 5,15-bis(3, 4', 4", 4"', 4", 4""', 4""", 4"""'-octahexyl-[2, 2'; 5', 2" 5", 2'"; 5"', 2""; 5"", 2""'; 5""', 2"""; 5""", 2"""']octithiophene-5-yl)-10, 20-bis(3, 5-ditertbutylphenyl)zinc(II)porphyrin (5) from trimethyl(3, 4', 4", 4'", 4......"", 4""', 4""", 4"""'-Octahexyl-[2, 2'; 5', 2"; 5"; 2'"; 5"', 2""; 5"", 2"'"; 5""', 2"""; 5""", 2"""']octithiophene-5-yl)stannane (3-SnMe3) and 5, 15-dibromo-10, 20-bis(3, 5-ditertbutylphenyl)zinc(II)porphyrin (6) by Stille coupling. All the products were characterised by size exclusion chromatography...

  5. A microscale synthesis of a promising radiolabelled antitumor drug: cis-1,1-cyclobutanedicarboxylato (2R)-2-methyl-1,4-butanediamine platinum(II), NK121

    International Nuclear Information System (INIS)

    Suwa, Masato; Kogawa, Osamu; Hashimoto, Yutaka

    1992-01-01

    A promising antitumor drug, cis-1,1-cyclobutane-dicarboxylato (2R)-2-methyl-1,4-butanediamine platinum (II), NK121, was synthesized from radionuclides of platinum such as 193m Pt, 195m Pt and 191 Pt which were produced by neutron irradiation of enriched 192 Pt. The overall yield was 38.6% in a synthesis time of 10 hours. The radioactivities present in 8.39 mg of NK121 were 115.3 μCi as 193m Pt, 29.9 μCi as 197 Pt, 22.0 μCi as 195m Pt, and 4.8 μCi as 191 Pt at the end of synthesis. The specific activity of the NK121 was 13.7 μCi ( 193m Pt)/mg NK121 at the end of synthesis. The radiochemical purity of NK121 was typically 99%. HPLC analyses confirmed that NK121 was in an adequate chemical purity and suitable for animal experimentation. (author)

  6. A microscale synthesis of a promising radiolabelled antitumor drug: cis-1,1-cyclobutanedicarboxylato (2R)-2-methyl-1,4-butanediamine platinum(II), NK121

    Energy Technology Data Exchange (ETDEWEB)

    Suwa, Masato; Kogawa, Osamu; Hashimoto, Yutaka (Nippon Kayaku Co. Ltd., Tokyo (Japan). Research Labs. of Pharmaceuticals Group); Nowatari, Hiroyoshi (Nippon Kayaku Co. Ltd., Takasaki, Gumma (Japan). Takasaki Research Labs.); Murase, Yuko; Homma, Yoshio (Kyoritsu Coll. of Pharmacy, Tokyo (Japan))

    1992-05-01

    A promising antitumor drug, cis-1,1-cyclobutane-dicarboxylato (2R)-2-methyl-1,4-butanediamine platinum (II), NK121, was synthesized from radionuclides of platinum such as {sup 193m}Pt, {sup 195m}Pt and {sup 191}Pt which were produced by neutron irradiation of enriched {sup 192}Pt. The overall yield was 38.6% in a synthesis time of 10 hours. The radioactivities present in 8.39 mg of NK121 were 115.3 {mu}Ci as {sup 193m}Pt, 29.9 {mu}Ci as {sup 197}Pt, 22.0 {mu}Ci as {sup 195m}Pt, and 4.8 {mu}Ci as {sup 191}Pt at the end of synthesis. The specific activity of the NK121 was 13.7 {mu}Ci ({sup 193m}Pt)/mg NK121 at the end of synthesis. The radiochemical purity of NK121 was typically 99%. HPLC analyses confirmed that NK121 was in an adequate chemical purity and suitable for animal experimentation. (author).

  7. Synthesis of diorganoplatinum(IV) complexes by the Ssbnd S bond cleavage with platinum(II) complexes

    Science.gov (United States)

    Niroomand Hosseini, Fatemeh; Rashidi, Mehdi; Nabavizadeh, S. Masoud

    2016-12-01

    Reaction of [PtR2(NN)] (R = Me, p-MeC6H4 or p-MeOC6H4; NN = 2,2‧-bipyridine, 4,4‧-dimethyl-2,2‧-bipyridine, 1,10-phenanthroline or 2,9-dimethyl-1,10-phenanthroline) with MeSSMe gives the platinum(IV) complexes cis,trans-[PtR2(SMe)2(NN)]. They are characterized by NMR spectroscopy and elemental analysis. The geometries and the nature of the frontier molecular orbitals of Pt(IV) complexes containing Ptsbnd S bonds are studied by means of the density functional theory.

  8. Behaviour of palladium(II), platinum(IV), and rhodium(III) in artificial and natural waters: Influence of reactor surface and geochemistry on metal recovery

    Energy Technology Data Exchange (ETDEWEB)

    Cobelo-Garcia, Antonio [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)]. E-mail: antonio.cobelo-garcia@plymouth.ac.uk; Turner, Andrew [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Millward, Geoffrey E. [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Couceiro, Fay [School of Earth, Ocean and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

    2007-03-07

    The recovery of dissolved platinum group elements (PGE: Pd(II), Pt(IV) and Rh(III)) added to Milli-Q[reg] water, artificial freshwater and seawater and filtered natural waters has been studied, as a function of pH and PGE concentration, in containers of varying synthetic composition. The least adsorptive and/or precipitative loss was obtained for borosilicate glass under most of the conditions employed, whereas the greatest loss was obtained for low-density polyethylene. Of the polymeric materials tested, the adsorptive and/or precipitative loss of PGE was lowest for fluorinated ethylene propylene (Teflon[reg]). The loss of Pd(II) in freshwater was significant due to its affinity for surface adsorption and its relatively low solubility. The presence of natural dissolved organic matter increases the recovery of Pd(II) but enhances the loss of Pt(IV). The loss of Rh(III) in seawater was significant and was mainly due to precipitation, whereas Pd(II) recovery was enhanced, compared to freshwater, because of its complexation with chloride. The results have important implications regarding protocols employed for sample preservation and controlled laboratory experiments used in the study of the speciation and biogeochemical behaviour of PGE.

  9. [Combination of adriamycin and cis-diammine-dichloro-platinum (II) in the treatment of advanced, therapy-resistant, ovarian carcinoma (author's transl)].

    Science.gov (United States)

    Cavalli, F; Stoller, U; Tschopp, L; Sonntag, R W; Brunner, K W

    1978-06-02

    Adriamycin (doxorubicin, Adriblastin) and cis-diammine-dichloro-platinum (II) (DDP, NSC 119 875) were used in the treatment of 18 patients with ovarian carcinoma, usually after intensive pre-treatment, both in a dosage of 50 mg/m2 once every 4 weeks. Forced diuresis was initiated at the same time. On average three such treatments were given. Six patients showed partial remission defined as decrease of tumour mass by more than 50% or as almost complete disappearance of ascites during more than two months without concomitant diuretic treatment. The remission time was 2+, 3, 3+, 3.5, 7+, and 9+ months. In all patients severe gastrointestinal toxicity occurred, however the myelosuppressive action was only moderate. Nephrotoxicity was negligible. Combined chemotherapy with Adriblastin and DDP thus seems effective even in intensively pretreated patients with ovarian carcinoma.

  10. Shedding light on the photophysical properties of newly designed platinum(II) complexes by adding substituents on functionalized ligands as highly efficient OLED emitters from a theoretical viewpoint

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jieqiong [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Wang, Li, E-mail: chemwangl@henu.edu.cn [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Wang, Xin [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); He, Chaozheng, E-mail: hecz2013@nynu.edu.cn [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061 (China); Zhang, Jinglai, E-mail: zhangjinglai@henu.edu.cn [Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

    2015-08-01

    The phosphorescent properties of three synthesized and three new designed platinum(II) complexes are focused on in this work. To reveal their structure–property relationships, a density functional theory/time-dependent density functional theory (DFT/TDDFT) investigation is performed on the geometric and electronic structures, absorption and emission spectra. The electroluminescent (EL) properties are evaluated by the ionization potential (IP), electron affinity (EA), and reorganization energy (λ). Furthermore, the radiative rate constant (k{sub r}) is qualitatively elucidated by various factors including the strength of the SOC interaction between the higher-lying singlet excited states (S{sub n}) and the T{sub 1} state, the oscillator strength (f) of the S{sub n} states that can couple with the T{sub 1} state, and the energy separation between the coupled states. A combined analysis of various elements that could affect the phosphorescent efficiency is beneficial to exploring efficient triplet phosphors in OLEDs. Consequently, complexes Pt-1 and 1 would be more suitable blue-emitting phosphorescent materials with balance of EL properties and acceptable quantum yields. - Graphical abstract: Display Omitted - Highlights: • The absorption and phosphorescence spectra of Pt(II) complexes are investigated. • Their Φ{sub em}, IP, EA, and reorganization energy are compared. • Three new Pt(II) complexes are designed.

  11. Unusual combination of Cis platinum and radiotherapy followed by a three fractions per day irradiation in splitcourse: a phase I-II study in brain glioma patients

    International Nuclear Information System (INIS)

    Ben-Hassel, M.; Lesimple, T.; Gedouin, D.; Chenal, C.; Guegan, Y.; Darcel, F.

    1992-01-01

    An unusual protocol based on a preliminary clinical study on cylindromas metastasized to the lung was proposed to brain glioma patients: Day 2 100 mg/m 2 i.v. Cis platinum (Cis P II) followed at days 3 and 5 by 6 Gy irradiation (RT) in two fractions and three days. Five cycles were scheduled at 21 days interval. On disease progression a three fractions per day radiotherapy regimen (3 FRT) in split-course (two series of 22.50 Gy in 15 fractions and five days separated by a two weeks period of rest) was then delivered to the patients. All patients had a measurable mass on the CT scan. 19 were entered into the study: 13 as first line therapy (group A) and six for salvage treatment (group B). Tolerance was globally good. Eight patients were considered responders at the end of five cycles of Cis II-RT. They were all group A patients. Median symptom-free interval was six months for the whole population. Survival was twelve months. The 3 FRT was well tolerated but does not seem to have improved the therapeutic gain of the chemoradiotherapy combination. The present study concerns patients whose prognosis was poor on inclusion: Surgery unadvisable or unsatisfactory and diagnosis mainly based on biopsy only. The number and the duration of responses justify further study into Cis P II as first line therapy as either an effective cytotoxic drug or a potential radio enhancer. (orig.) [de

  12. Recovery of platinum-group metals (PGMS from spent automotive catalysts: Part II: Automotive catalysts: Structures and principle of operation

    Directory of Open Access Journals (Sweden)

    Dimitrijević Mile D.

    2015-01-01

    Full Text Available Catalytic converters are incorporated into motor vehicle emission systems (passenger cars, trucks and other motor vehicles, as well as civil and agricultural machines, as of lately to reduce air pollution as well as to meet the emission standards. Their purpose is to convert toxic emissions generated by combustion of liquid fossil fuels into less harmful products. In catalytic converters, rhodium is used for the reduction of gasses, whereas platinum and palladium are used for the oxidation of gasses. This paper presents the structure and operating principle of automotive catalysts in view of the fact that cars are the most prevalent motor vehicles worldwide and due to the fact that the production of cars with gasoline and diesel engines will dominate until at least 2020.

  13. Molecular modeling of cationic porphyrin-anthraquinone hybrids as DNA topoisomerase IIβ inhibitors.

    Science.gov (United States)

    Arba, Muhammad; Ruslin; Ihsan, Sunandar; Tri Wahyudi, Setyanto; Tjahjono, Daryono H

    2017-12-01

    Human DNA Topoisomerase II has been regarded as a promising target in anticancer drug discovery. In the present study, we designed six porphyrin-anthraquinone hybrids bearing pyrazole or pyridine group as meso substituents and evaluated their potentials as DNA Topoisomerase IIβ inhibitor. First, we investigated the binding orientation of porphyrin hybrids into DNA topoisomerase IIβ employing AutoDock 4.2 and then performed 20-ns molecular dynamics simulations to see the dynamic stability of each porphyrin-Topo IIβ complex using Amber 14. We found that the binding of porphyrin hybrids occured through intercalation and groove binding mode in addition interaction with the amino acid residues constituting the active cavity of Topo IIβ. Each porphyrin-Topo IIβ complex was stabilized during 20-ns dynamics simulations. The MM-PBSA free energy calculation shows that the binding affinities of porphyrin hybrids were modified with the number of meso substituent. Interestingly, the affinity of all porphyrin hybrids to Topo IIβ was stronger than that of native ligand (EVP), indicating the potential of the designed porphyrin to be considered in experimental research. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Adsorption of platinum(IV) and palladium(II) from aqueous solution by thiourea-modified chitosan microspheres

    International Nuclear Information System (INIS)

    Zhou Limin; Liu Jinhui; Liu Zhirong

    2009-01-01

    The chitosan microparticles were prepared using the inverse phase emulsion dispersion method and modified with thiourea (TCS). TCS was characterized by scanning electron microscope (SEM), the Fourier transform infrared (FT-IR) spectra, sulfur elemental analysis, specific surface area and pore diameter. The effects of various parameters, such as pH, contact time, initial concentration and temperature, on the adsorption of Pt(IV) and Pd(II) by TCS were investigated. The results showed that the maximum adsorption capacity was found at pH 2.0 for both Pt(IV) and Pd(II). TCS can selectively adsorb Pt(IV) and Pd(II) from binary mixtures with Cu(II), Pb(II), Cd(II), Zn(II), Ca(II), and Mg(II). The adsorption reaction followed the pseudo-second-order kinetics, indicating the main adsorption mechanism of chemical adsorption. The isotherm adsorption equilibrium was well described by Langmuir isotherms with the maximum adsorption capacity of 129.9 mg/g for Pt(IV) and 112.4 mg/g for Pd(II). The adsorption capacity of both Pt(IV) and Pd(II) decreased with temperature increasing. The negative values of enthalpy (ΔH o ) and Gibbs free energy (ΔG o ) indicate that the adsorption process is exothermic and spontaneous in nature. The adsorbent was stable without loss of the adsorption capacity up to at least 5 cycles and the desorption efficiencies were above 95% when 0.5 M EDTA-0.5 M H 2 SO 4 eluent was used. The results also showed that the preconcentration factor for Pt(IV) and Pd(II) was 196 and 172, respectively, and the recovery was found to be more than 97% for both precious metal ions.

  15. Experimental studies on the nature of bonding of DNA/bipyridyl-(ethylenediamine)platinum(II) and DNA/netropsin complexes in solution and oriented wet-spun films

    Science.gov (United States)

    Marlowe, R. L.; Szabo, A.; Lee, S. A.; Rupprecht, A.

    2002-03-01

    The stability of complexes of NaDNA with bipyridyl-(ethylenediamine)platinum(II) (abbreviated [(bipy)Pt(en)]) and with netropsin has been studied using two techniques: (i) ultraviolet melting experiments were done on NaDNA/[(bipy)Pt(en)], showing that the [(bipy)Pt(en)] ligand stabilizes the DNA double helix structure; and (ii) swelling measurements (via optical microscopy) as a function of relative humidity were done on wet-spun oriented films of NaDNA/[(bipy)Pt(en)] and of NaDNA/netropsin. The swelling data shows that an irreversible transition of the films occurs at high relative humidity, first for the NaDNA/netropsin, then for pure NaDNA, and lastly for the NaDNA/[(bipy)Pt(en)]. These results are indicative that the [(bipy)Pt(en)] complex stabilizes the intermolecular bonds which mediate the film swelling characteristics. A model is suggested for the binding of [(bipy)Pt(en)] to DNA to explain why the swelling experiments show this ligand as increasing the intermolecular bond strength between the DNA double helices, while netropsin decreases this degree of stabilization.

  16. Stepwise π-extension of meso-alkylidenyl porphyrins through sequential 1,3-dipolar cycloaddition and redox reactions.

    Science.gov (United States)

    Park, Dowoo; Jeong, Seung Doo; Ishida, Masatoshi; Lee, Chang-Hee

    2014-08-25

    Several regioselectively π-extended, pyrrole fused porphyrinoids have been synthesized by the 1,3-dipolar cycloaddition of meso-alkylidene-(benzi)porphyrins. Pd(II) complexes gave oxidation resistant, bis-pyrrole fused adducts. The repeated 1,3-dipolar cycloaddition followed by oxidation-reduction of pentaphyrin analogs afforded π-extended porphyrin analogs.

  17. Microscopic modeling of gas-surface scattering: II. Application to argon atom adsorption on a platinum (111) surface

    Science.gov (United States)

    Filinov, A.; Bonitz, M.; Loffhagen, D.

    2018-06-01

    A new combination of first principle molecular dynamics (MD) simulations with a rate equation model presented in the preceding paper (paper I) is applied to analyze in detail the scattering of argon atoms from a platinum (111) surface. The combined model is based on a classification of all atom trajectories according to their energies into trapped, quasi-trapped and scattering states. The number of particles in each of the three classes obeys coupled rate equations. The coefficients in the rate equations are the transition probabilities between these states which are obtained from MD simulations. While these rates are generally time-dependent, after a characteristic time scale t E of several tens of picoseconds they become stationary allowing for a rather simple analysis. Here, we investigate this time scale by analyzing in detail the temporal evolution of the energy distribution functions of the adsorbate atoms. We separately study the energy loss distribution function of the atoms and the distribution function of in-plane and perpendicular energy components. Further, we compute the sticking probability of argon atoms as a function of incident energy, angle and lattice temperature. Our model is important for plasma-surface modeling as it allows to extend accurate simulations to longer time scales.

  18. Porphyrins at interfaces

    Science.gov (United States)

    Auwärter, Willi; Écija, David; Klappenberger, Florian; Barth, Johannes V.

    2015-02-01

    Porphyrins and other tetrapyrrole macrocycles possess an impressive variety of functional properties that have been exploited in natural and artificial systems. Different metal centres incorporated within the tetradentate ligand are key for achieving and regulating vital processes, including reversible axial ligation of adducts, electron transfer, light-harvesting and catalytic transformations. Tailored substituents optimize their performance, dictating their arrangement in specific environments and mediating the assembly of molecular nanoarchitectures. Here we review the current understanding of these species at well-defined interfaces, disclosing exquisite insights into their structural and chemical properties, and also discussing methods by which to manipulate their intramolecular and organizational features. The distinct characteristics arising from the interfacial confinement offer intriguing prospects for molecular science and advanced materials. We assess the role of surface interactions with respect to electronic and physicochemical characteristics, and describe in situ metallation pathways, molecular magnetism, rotation and switching. The engineering of nanostructures, organized layers, interfacial hybrid and bio-inspired systems is also addressed.

  19. Luminescent platinum(II) complexes with functionalized N-heterocyclic carbene or diphosphine selectively probe mismatched and abasic DNA

    OpenAIRE

    Che, CM; Chen, T; To, WP; Zou, T; FUNG, SK; Lok, CN; YANG, C; Cao, B

    2016-01-01

    The selective targeting of mismatched DNA overexpressed in cancer cells is an appealing strategy in designing cancer diagnosis and therapy protocols. Few luminescent probes that specifically detect intracellular mismatched DNA have been reported. Here we used Pt(II) complexes with luminescence sensitive to subtle changes in the local environment and report several Pt(II) complexes that selectively bind to and identify DNA mismatches. We evaluated the complexes' DNA-binding characteristics by ...

  20. Synthesis of carbon-14 labelled cis-malonato [(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane] platinum(II) (SKI 2053R)

    International Nuclear Information System (INIS)

    Kim, Dae-Kee; Kim, Youngseok; Rim, Jonggill; Kim, Ganghyeok; Gam, Jongsik; Song, Sungkun; Yoo, Kwanghee; Kim, Key H.

    1994-01-01

    The synthesis of 14 C-labelled cis-malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolan e]platinum(II) from [1,4- 14 C] D-tartaric acid is described. The overall radiochemical yield of the product in a eight-step sequence was 23.8% and radiochemical purity was 98.5%. (author)

  1. Synthesis and characterization of a novel meso-porphyrin and its metallo derivatives

    Directory of Open Access Journals (Sweden)

    Paulo Cesar Bega

    2014-02-01

    Full Text Available There has been a growing interest in the properties of substituted meso-tetraarylporphyrins and metallo porphyrins as catalysts for oxidation of hydrocarbons, oxygen detection, among others. This work describes the synthesis of a new porphyrin, 5,10,15,20-tetrakis(4-butoxy-3-methoxyphenylporphyrin, and its metallo complexes. Herein it was used a readily available reactant, vanillin, as starting material which was submitted to alkylation with n-bromobutane affording the synthetic precursor. The desired porphyrin was obtained by reacting the O-alkylated aldehyde with pyrrole in the presence of propionic acid (Alder-Longo method. The purified porphyrin was then subjected to the metallation process using iron (II and manganese (II salts. The synthesized compounds were characterized by IR, UV-Vis, NMR and EPR spectroscopy.

  2. Platinum(II Complexes with Tetradentate Schiff Bases as Ligands: Synthesis, Characterization and Detection of DNA Interaction by Differential Pulse Voltammetry

    Directory of Open Access Journals (Sweden)

    Lijun Li

    2012-01-01

    Full Text Available Five sterically hindered platinum(II complexes with tetradentate schiff bases as ligands, [Pt(L] (L= N,N′-bisalicylidene-1,2-ethylenediamine (L1, N,N′-bisalicylidene-1,2-cyclohexanediamine (L2, N,N′-bis(5-hydroxyl-salicylidene-1,2-cyclohexanediamine (L3, N,N′-bisalicylidene-1,2-diphenyl-ethylenediamine (L4 and N,N′-bis(3-tert-butyl-5-methyl-salicylidene-1,2-diphenylethylenediamine (L5 have been synthesized and characterized by IR spectroscopy and elemental analysis. The sterical hindrance of antitumor drug candidates potentially makes them less susceptible to deactivation by sulphur containing proteins and helping to overcome resistance mechanisms. The interaction of these metal complexes with fish sperm single-stranded DNA (ssDNA was studied electrochemically based on the oxidation signals of guanine and adenine. Differential pulse voltammetry was employed to monitor the DNA interaction in solution by using renewable pencil graphite electrode. The results indicate that ligands with different groups can strongly affect the interaction between [Pt(L] complexes and ssDNA due to sterical hindrances and complex [Pt(L1] has the best interaction with DNA among the five complexes.

  3. Bright, Multi-responsive, Sky-Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework.

    Science.gov (United States)

    Liu, Lijie; Wang, Xiang; Wang, Nan; Peng, Tai; Wang, Suning

    2017-07-24

    A new class of highly efficient and stable, blue-phosphorescent Pt II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching-from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi-response phenomenon. Highly efficient singlet-oxygen sensitization by the Pt II compounds yields UV-light-induced phosphorescence enhancement and color switching. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. cis-Dichlorido(dimethyl sulfoxide-κS(N,N,N′,N′-tetramethylguanidine-κN′′platinum(II

    Directory of Open Access Journals (Sweden)

    Ivan I. Eliseev

    2013-02-01

    Full Text Available In the title compound, cis-[PtCl2(C5H13N3(C2H6OS], the four-coordinate PtII atom is bonded to one N atom of the N,N,N′,N′-tetramethylguanidine ligand, one dimethyl sulfoxide S atom and two chloride ligands, forming a cis-square-planar geometry. The bond lengths and angles of the N—Pt—Cl functionality are typical for imine dichloridoplatinum(II complexes. The H atom of the imino group is oriented towards the O atom of the sulfoxide group of a neighboring molecule and forms an N—H...O hydrogen bond.

  5. Interaction of cationic porphyrins with DNA: Importance of the number and position of the charges and minimum structural requirements for intercalation

    International Nuclear Information System (INIS)

    Sari, M.A.; Battioni, J.P.; Dupre, D.; Mansuy, D.; Le Pecq, J.B.

    1990-01-01

    Thirty-three porphyrins or metalloporphyrins corresponding to the general formula [meso-[N-methyl-4(or 3 or 2)-pyridiniumyl] n (aryl) 4-n porphyrin]M (M = H 2 , Cu II , or ClFe III ), with n = 2-4, have been synthesized and characterized by UV-visible and 1 H NMR spectroscopy and mass spectrometry. These porphyrins differ not only in the number (2-4) and position of their cationic charges but also in the steric requirements to reach even temporarily a completely planar geometry. Interaction of these porphyrins or metalloporphyrins with calf thymus DNA has been studied and their apparent affinity binding constants have been determined by use of a competition method with ethidium bromide which was applicable not only for all the free base porphyrins but also for their copper (II) or iron (III) complexes. Whatever their mode of binding may be, their apparent affinity binding constants were relatively high and a linear decrease of log K app with the number of porphyrin charges was observed. Studies of porphyrin-DNA interactions by UV and fluorescence spectroscopy, viscosimetry, and fluorescence energy transfer experiments showed that not only the tetracationic meso-tetrakis[N-methyl-4(or 3)-pyridiniumyl]porphyrins, which both involved four freely rotating meso-aryl groups, but also the corresponding tri- and dicationic porphyrins were able to intercalate into calf thymus DNA. These results show that only half of the porphyrin ring is necessary for intercalation to occur

  6. Solvent extraction of platinum with thiobenzanilide. Separation of platinum from copper

    International Nuclear Information System (INIS)

    Shkil', A.N.; Zolotov, Yu.A.

    1989-01-01

    The solvent extraction of micro concentrations of platinum has been investigated from hydrochloric acid media using thiobenzanilide in the presence of SnCl 2 and KI. In the presence of SnCl 2 platinum is extracted rapidly and to significant completion. Conditions have been developed for the quantitative extraction of platinum. The authors have also examined the solvent extraction of copper(II) using thiobenzanilide, interference due to copper(II) and iron(III) on solvent extraction of platinum, and methods to suppress this interference. A procedure has also been developed for the separation of platinum from copper. Solvent extraction of metals was studied using radioactive isotopes: 197 Pt, 64 Cu, 59 Fe, 198 Au, 109 Pd, 110m Ag

  7. A study of the structure-property relationship of azole-azine based homoleptic platinum(II) complexes and tunability of the photo-physical properties

    Science.gov (United States)

    Ranga Prabhath, Malaviarachchige Rabel

    Owing to superior energy efficiency, Light Emitting Diode (OLED) technology has become considerably commercialised over the last decade. Innovations in this field have been spurred along by the discovery of new molecules with good stability and high emission intensity, followed through by intense engineering efforts. Emissive transition metal complexes are potent molecular emitters as a result of their high quantum efficiencies related to facile intersystem crossing (ISC) between excited-state manifolds (efficient spin orbit coupling (SOC)) and resultant efficient emission from the triplet state (phosphorescence). These also allow rational tuning of the emission wavelengths. Tuning of the ground and excited state energies, and thus emission wavelength of these complexes can be achieved by subtle structural changes in the organic ligands. Pyridyl-triazole ligands have started receiving increasing attention in recent years as strong field ligands that are relatively straightforward to synthesise. In this study we explore the emission tunability of a newly synthesised series of 5-subsituted-Pyridyl-1,2,3-triazole-based ligands and their Pt(II) complexes. Studies have shown, substitution at the triazole moiety is less effective in achieving emission tunability. Alternatively we carried out the substitution at the 5th position of the pyridine ring with a wide range of electronically diverse, donor-acceptor groups (-N(CH3)2, -H, -CHO, -CHC(CN)2). The target ligands were approached through the serial application of the Sonogashira carbon-carbon coupling and the Sharpless copper-catalyzed Huisgen’s 1,3-dipolarcycloaddition procedures. As a result, coarse tunability of excimer emission was observed in thin-films, generating blue-(486 nm), green-(541 nm), orange-(601 nm) and red-(625 nm) luminescence respectively. This “turned-on” substituent effect was accounted for metallophilic Pt—Pt interaction-induced aggregates in the solid state. Excited state calculations

  8. The synthesis of chlorophyll-a biosynthetic precursors and methyl substituted iron porphyrins

    International Nuclear Information System (INIS)

    Matera, K.M.

    1988-01-01

    The biosynthetic intermediates were incubated in a plant system. The activity levels calculated show that magnesium 6-acrylate porphyrins and one of the magnesium 6-β-hydroxypropionate porphyrins are not intermediates. In addition, plant systems incubated with 18 O 2 were found to synthesize magnesium 2,4-divinyl pheoporphyrin-a 5 incorporated with 18 O at the 9-carbonyl oxygen. Mass spectroscopy confirmed the presence of the oxygen label, thus eliminating one of two hypothesized pathways to chlorophyll-a. An overall description is given of iron porphyrins and iron porphyrin containing proteins. The function of the propionic side chains of the heme prosthetic group during electron transport reactions will be investigated. The synthesis of a series of iron(III) hexamethyl porphyrins with increasingly longer substituents in the remaining two peripheral positions of the porphyrin is described. Models for NMR studies of iron chlorin containing enzymes are discussed. Iron(III) pyropheophorbide-a and methyl pyropheophorbide-a were synthesized in addition to 5-CD 3 , 10-CD 2 iron(III) pyropheophorbide-a and methyl pyropheophorbide-a. Together, these pyropheophorbides were used to assign NMR resonances and ultimately provide a model for other iron chlorins. The synthesis of nickel(II) anhydro-mesorhodoporphyrin from zinc(III) anhydromesorhodochlorin is described; this nickel porphyrin was used as a standard for ring current calculations of reduced nickel analogs of anhydromesorhodoporphyrin

  9. Unusual near-white electroluminescence of light emitting diodes based on saddle-shaped porphyrins.

    Science.gov (United States)

    Shahroosvand, Hashem; Zakavi, Saeed; Sousaraei, Ahmad; Mohajerani, Ezeddin; Mahmoudi, Malek

    2015-05-14

    In contrast to the red electroluminescence emission frequently observed in porphyrins based OLED devices, the present devices exhibit a nearly white emission with greenish yellow, yellowish green and blue green hues in the case of Fe(II)(TCPPBr6) (TCPPBr6 = β-hexabromo-meso-tetrakis-(4-phenyl carboxyl) porphyrinato), Zn(II)(TPPBr6) and Co(II)(TPPBr6), respectively.

  10. A label-free colorimetric aptasensor for simple, sensitive and selective detection of Pt (II) based on platinum (II)-oligonucleotide coordination induced gold nanoparticles aggregation.

    Science.gov (United States)

    Fan, Daoqing; Zhai, Qingfeng; Zhou, Weijun; Zhu, Xiaoqing; Wang, Erkang; Dong, Shaojun

    2016-11-15

    Herein, a gold nanoparticles (AuNPs) based label-free colorimetric aptasensor for simple, sensitive and selective detection of Pt (II) was constructed for the first time. Four bases (G-G mismatch) mismatched streptavidin aptamer (MSAA) was used to protect AuNPs from salt-induced aggregation and recognize Pt (II) specifically. Only in the presence of Pt (II), coordination occurs between G-G bases and Pt (II), leading to the activation of streptavidin aptamer. Streptavidin coated magnetic beads (MBs) were used as separation agent to separate Pt (II)-coordinated MSAA. The residual less amount of MSAA could not efficiently protect AuNPs anymore and aggregation of AuNPs will produce a colorimetric product. With the addition of Pt (II), a pale purple-to-blue color variation could be observed by the naked eye. A detection limit of 150nM and a linear range from 0.6μM to 12.5μM for Pt (II) could be achieved without any amplification. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Enhanced photocatalytic degradation activity over TiO{sub 2} nanotubes co-sensitized by reduced graphene oxide and copper(II) meso-tetra(4-carboxyphenyl)porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Meng; Wan, Junmin, E-mail: wwjm2001@126.com; Hu, Zhiwen; Peng, Zhiqin; Wang, Bing

    2016-07-30

    Highlights: • CuTCPP/rGO-TNT photocatalysts are synthesized. • CuTCPP and rGO are helpful to induce interfacial charge transfer at surface junction. • CuTCPP and rGO are favorable for enhancing co-photocatalytic activity. • A deeper insight into the co-photocatalytic mechanism is put forward. • The photocatalyst are proven to be effective and chemically-stable catalysts. - Abstract: In this paper, TiO{sub 2} nanotubes (TNT) co-sensitized with copper(II) meso-tetra(4-carboxyphenyl)porphyrin (CuTCPP) and reduced graphene oxide nanosheets (rGO), which was fabricated through two-step improved hydrothermal method and heating reflux process. The effect of rGO and CuTCPP on the co-photocatalytic behavior of TNT for the degradation of Methylene Blue (MB) were measured under visible light irradiation. The photocatalysts have been characterized and analyzed by high-resolution transmission electron microscopy (TEM), selected area electronic diffraction (SAED), elemental mapping by energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and electron paramagnetic resonance (EPR). The results provide a deeper insight into the co-photocatalytic mechanism of CuTCPP/rGO-TNT nanocomposites. The degradation results showed a purification of more than 95% MB in wastewater, which is about 5 times higher than that of the pure TNT. The results also confirm the prepared CuTCPP/rGO-TNT nanocomposites possess superior co-photocatalytic activities.

  12. Porphyrins Fused with Unactivated Polycyclic Aromatic Hydrocarbons

    KAUST Repository

    Diev, Vyacheslav V.; Schlenker, Cody W.; Hanson, Kenneth; Zhong, Qiwen; Zimmerman, Jeramy D.; Forrest, Stephen R.; Thompson, Mark E.

    2012-01-01

    A systematic study of the preparation of porphyrins with extended conjugation by meso,β-fusion with polycyclic aromatic hydrocarbons (PAHs) is reported. The meso-positions of 5,15-unsubstituted porphyrins were readily functionalized with PAHs. Ring fusion using standard Scholl reaction conditions (FeCl 3, dichloromethane) occurs for perylene-substituted porphyrins to give a porphyrin β,meso annulated with perylene rings (0.7:1 ratio of syn and anti isomers). The naphthalene, pyrene, and coronene derivatives do not react under Scholl conditions but are fused using thermal cyclodehydrogenation at high temperatures, giving mixtures of syn and anti isomers of the meso,β-fused porphyrins. For pyrenyl-substituted porphyrins, a thermal method gives synthetically acceptable yields (>30%). Absorption spectra of the fused porphyrins undergo a progressive bathochromic shift in a series of naphthyl (λ max = 730 nm), coronenyl (λ max = 780 nm), pyrenyl (λ max = 815 nm), and perylenyl (λ max = 900 nm) annulated porphyrins. Despite being conjugated with unsubstituted fused PAHs, the β,meso-fused porphyrins are more soluble and processable than the parent nonfused precursors. Pyrenyl-fused porphyrins exhibit strong fluorescence in the near-infrared (NIR) spectral region, with a progressive improvement in luminescent efficiency (up to 13% with λ max = 829 nm) with increasing degree of fusion. Fused pyrenyl-porphyrins have been used as broadband absorption donor materials in photovoltaic cells, leading to devices that show comparatively high photovoltaic efficiencies. © 2011 American Chemical Society.

  13. Porphyrins Fused with Unactivated Polycyclic Aromatic Hydrocarbons

    KAUST Repository

    Diev, Vyacheslav V.

    2012-01-06

    A systematic study of the preparation of porphyrins with extended conjugation by meso,β-fusion with polycyclic aromatic hydrocarbons (PAHs) is reported. The meso-positions of 5,15-unsubstituted porphyrins were readily functionalized with PAHs. Ring fusion using standard Scholl reaction conditions (FeCl 3, dichloromethane) occurs for perylene-substituted porphyrins to give a porphyrin β,meso annulated with perylene rings (0.7:1 ratio of syn and anti isomers). The naphthalene, pyrene, and coronene derivatives do not react under Scholl conditions but are fused using thermal cyclodehydrogenation at high temperatures, giving mixtures of syn and anti isomers of the meso,β-fused porphyrins. For pyrenyl-substituted porphyrins, a thermal method gives synthetically acceptable yields (>30%). Absorption spectra of the fused porphyrins undergo a progressive bathochromic shift in a series of naphthyl (λ max = 730 nm), coronenyl (λ max = 780 nm), pyrenyl (λ max = 815 nm), and perylenyl (λ max = 900 nm) annulated porphyrins. Despite being conjugated with unsubstituted fused PAHs, the β,meso-fused porphyrins are more soluble and processable than the parent nonfused precursors. Pyrenyl-fused porphyrins exhibit strong fluorescence in the near-infrared (NIR) spectral region, with a progressive improvement in luminescent efficiency (up to 13% with λ max = 829 nm) with increasing degree of fusion. Fused pyrenyl-porphyrins have been used as broadband absorption donor materials in photovoltaic cells, leading to devices that show comparatively high photovoltaic efficiencies. © 2011 American Chemical Society.

  14. Bis(di-2-pyridylamine-κ2N2,N2'platinum(II dibromide monohydrate

    Directory of Open Access Journals (Sweden)

    Kwang Ha

    2012-04-01

    Full Text Available The asymmetric unit of the title compound, [Pt(C10H9N32]Br2·H2O, contains two crystallographically independent half-molecules of the cationic PtII complex, two Br− anions and a lattice water molecule; an inversion centre is located at the centroid of each complex. Each PtII ion is four-coordinated in an essentially square-planar environment by four pyridine N atoms derived from the two chelating di-2-pyridylamine (dpa ligands, and the PtN4 unit is exactly planar. The chelate ring formed by the dpa ligand displays a boat conformation, with dihedral angles between the pyridine rings of 35.9 (2 and 41.0 (2°. The complex cations, Br− anions and solvent water molecules are linked by O—H...Br, N—H...Br, C—H...O and C—H...Br hydrogen bonds, forming a three-dimensional network.

  15. Platinum(II/palladium(II complexes with n-propyldithiocarbamate and 2,2′-bipyridine: synthesis, characterization, biological activity and interaction with calf thymus DNA

    Directory of Open Access Journals (Sweden)

    Hassan Mansouri-Torshizi

    2014-12-01

    Full Text Available Two Pd(II and Pt(II complexes ([Pt(bpy(pr-dtc]Br and [Pd(bpy(pr-dtc]Br, where bpy=2, 2′-bipyridine and pr-dtc = n-propyldithiocarbamate were synthesized and characterized by elemental analysis (CHN, molar conductivity measurements, Fourier transform infrared, 1H nuclear magnetic resonance and UV–visible techniques. In these complexes, the dithiocarbamato ligand coordinates to Pt(II or Pd(II center as bidentate with two sulfur atoms. The binding of these complexes to calf thymus DNA (CT-DNA was investigated using various physicochemical methods such as spectrophotometric, spectrofluorometric and gel filtration technique. The experimental results indicate that Pt(II and Pd(II complexes interact with CT-DNA in the intercalative mode. Both complexes unexpectedly denatured DNA at low concentration. Gel filtration studies indicated that the binding of complexes with DNA is strong enough and does not break readily. The cytotoxic activity of these metal complexes has been tested against human cell tumor lines (K562 and revealed much lower 50% cytotoxic concentration (Cc50 less than that of cisplatin. Several binding and thermodynamic parameters are also described.

  16. Mixed ligand complexes of platinum(II) and palladium(II) with cytokinin-derived compounds Bohemine and Olomoucine: X-ray structure of [Pt(BohH+-N7)Cl(3)].9/5H2O [Boh=6-(benzylamino)-2-[(3-(hydroxypropyl)-amino]-9-isopropylpurine, Bohemine

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Zdeněk; Maloň, M.; Zatloukal, Marek; Doležal, Karel; Strnad, Miroslav

    2003-01-01

    Roč. 94, č. 4 (2003), s. 307-316 ISSN 0162-0134 R&D Projects: GA ČR GA522/01/0275; GA ČR GA203/00/0152 Institutional research plan: CEZ:AV0Z5038910 Keywords : Platinum(II) * Palladium(II) * Bohemine Subject RIV: CE - Biochemistry Impact factor: 2.343, year: 2003

  17. DNA-protein crosslinking by trans-platinum(II)diamminedichloride in mammalian cells, a new method of analysis

    International Nuclear Information System (INIS)

    Kohn, K.W.; Ewig, R.A.G.

    1979-01-01

    DNA-protein crosslinks produced in mouse leukemia L1210 cells by trans-Pt(II)diamminedichloride were quantitated using the technique of DNA alkaline elution. DNA single-strand segments that were or were not linked to protein were separable into distinct components by alkaline elution after exposure of the cells to 2-15 kR of X-ray. Protein-linked DNA strands were separated on the basis of their retention on filters at pH 12 while free DNA strands of the size generated by 2-15 kR of X-ray passed rapidly through the filters. The retention of protein-linked DNA strands was attributable to adsorption of protein to the filter under the conditions of alkaline elution. The results obeyed a simple quantitative model according to which the frequency of DNA-protein crosslinks could be calculated. (Auth.)

  18. Decomposition of Intermolecular Interactions in the Crystal Structure of Some Diacetyl Platinum(II Complexes: Combined Hirshfeld, AIM, and NBO Analyses

    Directory of Open Access Journals (Sweden)

    Saied M. Soliman

    2016-12-01

    Full Text Available Intermolecular interactions play a vital role in crystal structures. Therefore, we conducted a topological study, using Hirshfeld surfaces and atom in molecules (AIM analysis, to decompose and analyze, respectively, the different intermolecular interactions in six hydrazone-diacetyl platinum(II complexes. Using AIM and natural bond orbital (NBO analyses, we determined the type, nature, and strength of the interactions. All the studied complexes contain C-H⋯O interactions, and the presence of bond critical points along the intermolecular paths underlines their significance. The electron densities (ρ(r at the bond critical points (0.0031–0.0156 e/a03 fall within the typical range for H-bonding interactions. Also, the positive values of the Laplacian of the electron density (∇2ρ(r revealed the depletion of electronic charge on the interatomic path, another characteristic feature of closed-shell interactions. The ratios of the absolute potential energy density to the kinetic energy density (|V(r|/G(r and ρ(r are highest for the O2⋯H15-N3 interaction in [Pt(COMe2(2-pyCMe=NNH2] (1; hence, this interaction has the highest covalent character of all the O⋯H intermolecular interactions. Interestingly, in [Pt(COMe2(H2NN=CMe-CMe=NNH2] (3, there are significant N-H⋯Pt interactions. Using the NBO method, the second-order interaction energies, E(2, of these interactions range from 3.894 to 4.061 kJ/mol. Furthermore, the hybrid Pt orbitals involved in these interactions are comprised of dxy, dxz, and s atomic orbitals.

  19. New palladium(II) and platinum(II) 5,5-diethylbarbiturate complexes with 2-phenylpyridine, 2,2'-bipyridine and 2,2'-dipyridylamine: synthesis, structures, DNA binding, molecular docking, cellular uptake, antioxidant activity and cytotoxicity.

    Science.gov (United States)

    Icsel, Ceyda; Yilmaz, Veysel T; Kaya, Yunus; Samli, Hale; Harrison, William T A; Buyukgungor, Orhan

    2015-04-21

    Novel palladium(ii) and platinum(ii) complexes of 5,5-diethylbarbiturate (barb) with 2-phenylpyridine (Hppy), 2,2'-bipyridine (bpy) and 2,2'-dipyridylamine (dpya) have been prepared and characterized by elemental analysis, IR, UV-Vis, NMR and ESI-MS. Single-crystal diffraction measurements show that complex consists of binuclear [Pd2(μ-barb-κN,O)2(ppy-κN,C)2] moieties, while complexes are mononuclear, [M(barb-κN)2(L-κN,N')] (L = bpy or dpya). has a composition of [Pt(dpya-κN,N')2][Ag(barb-κN)2]2·4H2O and was assumed to have a structure of [Pt(barb-κN)(Hppy-κN)(ppy-κN,C)]·3H2O. The complexes were found to exhibit significant DNA binding affinity by a non-covalent binding mode, in accordance with molecular docking studies. In addition, complexes and displayed strong binding with supercoiled pUC19 plasmid DNA. Cellular uptake studies were performed to assess the subcellular localization of the selected complexes. A moderate radical scavenging activity of and was confirmed by DPPH and ABTS tests. Complexes , , and showed selectivity against HT-29 (colon) cell line.

  20. The effect of cis-diammine dichloro platinum(II) on radiation injury in the rat bowel

    International Nuclear Information System (INIS)

    Lee, Kyung Ja; Rhee, Chung Sik

    1995-01-01

    This experimental study was performed for evaluate the effects of cis-diamminedichloroplatinum(II) (cis-DDP) on the radiation injury of rat bowel by histopathologic changes. Rats were exposed to entire abdomen by a single doses of X-ray(6-10 Gy) without or with cis-DDP(2.5mg/kg). Rats were divided into 3 groups such as radiation alone, cis-DDP alone and combined group. In combined group, cis-DDP was given 30 minutes before or immediately after irradiation. Cis-DDP induced the inflammatory cell infiltrations with focal necrosis of the mucosa in the small bowel and no abnormal change in the large bowel. In radiation alone group, mucosal necrosis, submucosal fibrosis and muscular necrosis were prominent changes in small bowel and submucosal fibrosis in the large bowel. The submucosal fibrosis in the small bowel was appeared in 10 Gy of radiation alone group and 8 Gy of cis-DDP infusion after radiation and 6 Gy of cis-DDP infusion before radiation of combined group. In the large bowel, submucosal fibrosis was noted in 8 Gy of radiation alone group 8 Gy of cis-DDP infusion after radiation and 6 Gy of cis-DDP infusion before radiation of combined group. In the small bowel, the enhancement ratio was 1.67 in a group of cis-DDP infusion before radiation and 1.25 in group of cis-DDP infusion after radiation as the end point was the submucosal fibrosis. In the large bowel, the enhancement ratio was 1.33 in a group of cis-DDP infusion before radiation and 1.0 in a group of cis-DDP infusion after radiation as the end point was the submucosal fibrosis. This study suggested that cis-DDP enhance the radiation effect in the small and large bowel especially when cis-DDP was infused before radiation

  1. N -annulated perylene as an efficient electron donor for porphyrin-based dyes: Enhanced light-harvesting ability and high-efficiency Co(II/III)-based dye-sensitized solar cells

    KAUST Repository

    Luo, Jie; Xu, Mingfei; Li, Renzhi; Huang, Kuo-Wei; Jiang, Changyun; Qi, Qingbiao; Zeng, Wangdong; Zhang, Jie; Chi, Chunyan; Wang, Peng; Wu, Jishan

    2014-01-01

    Porphyrin-based dyes recently have become good candidates for dye-sensitized solar cells (DSCs). However, the bottleneck is how to further improve their light-harvesting ability. In this work, N-annulated perylene (NP) was used to functionalize

  2. Trans-ligand-dependent arrangement (bent or linear) of Pt II-bound dialkylcyanamide ligands: Molecular structure of trans-dichloro(dimethylcyanamide)(dimethyl sulfoxide)platinum(II)

    Science.gov (United States)

    Anisimova, Tatyana B.; Bokach, Nadezhda A.; Fritsky, Igor O.; Haukka, Matti

    2011-11-01

    The title compound, trans-[PtCl 2(NCNMe 2)(Me 2SO)], is the first example of the structurally characterized Pt II species having the nitrile and the sulfoxide ligands in the trans-position to each other. The most significant feature of this structure is the non-linear arrangement of the Pt sbnd N1 sbnd C1 fragment providing the rare case of the bent form of the dialkylcyanamide ligand.

  3. Ultrafast Photoinduced Electron Transfer in a π-Conjugated Oligomer/Porphyrin Complex

    KAUST Repository

    Aly, Shawkat Mohammede

    2014-10-02

    Controlling charge transfer (CT), charge separation (CS), and charge recombination (CR) at the donor-acceptor interface is extremely important to optimize the conversion efficiency in solar cell devices. In general, ultrafast CT and slow CR are desirable for optimal device performance. In this Letter, the ultrafast excited-state CT between platinum oligomer (DPP-Pt(acac)) as a new electron donor and porphyrin as an electron acceptor is monitored for the first time using femtosecond (fs) transient absorption (TA) spectroscopy with broad-band capability and 120 fs temporal resolution. Turning the CT on/off has been shown to be possible either by switching from an organometallic oligomer to a metal-free oligomer or by controlling the charge density on the nitrogen atom of the porphyrin meso unit. Our time-resolved data show that the CT and CS between DPP-Pt(acac) and cationic porphyrin are ultrafast (approximately 1.5 ps), and the CR is slow (ns time scale), as inferred from the formation and the decay of the cationic and anionic species. We also found that the metallic center in the DPP-Pt(acac) oligomer and the positive charge on the porphyrin are the keys to switching on/off the ultrafast CT process.

  4. Design of a novel theranostic nanomedicine: synthesis and physicochemical properties of a biocompatible polyphosphazene–platinum(II conjugate

    Directory of Open Access Journals (Sweden)

    Avaji PG

    2016-03-01

    Full Text Available Prakash G Avaji,1,2,* Jung Hyun Park,1,* Hyun Jeong Lee,1 Yong Joo Jun,2 Kyung Su Park,3 Kyung Eun Lee,3 Soo-Jin Choi,4 Hwa Jeong Lee,1 Youn Soo Sohn2 1Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul, Republic of Korea; 2C & Pharm, Ewha Womans University, Seoul, Republic of Korea; 3Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, Republic of Korea; 4Department of Food Science and Technology, Seoul Women’s University, Seoul, Republic of Korea *These authors contributed equally to this work Abstract: To develop a theranostic nanomedicine involving the antitumor-active moiety (dachPt(II (dach: trans-(±-1,2-diaminocyclohexane of oxaliplatin (OX, a new biocompatible polyphosphazene carrier polymer was designed by grafting with a methoxy poly(ethylene glycol (MPEG to increase duration of circulation in the blood and with aminoethanol (AE as a spacer group. The antitumor (dachPt moiety was conjugated to the carrier polymer using cis-aconitic acid (AA as a linker, resulting in a polymer conjugate formulated as [NP(MPEG550(AE-AAPt(dach]n, named “Polyplatin” (PP. PP was found to self-assemble into very stable polymeric nanoparticles with a mean diameter of 55.1 nm and a critical aggregation concentration of 18.5 mg/L in saline. PP could easily be labeled with a fluorescence dye such as Cy5.5 for imaging studies. The time-dependent ex vivo image studies on organ distributions and clearance of Cy-labeled PP have shown that PP accumulated in the tumor with high selectivity by the enhanced permeability and retention effect but was cleared out from all the major organs including the liver in about 4 weeks postinjection. Another time-dependent bioimaging study on distribution and clearance of PP in mouse kidney using laser ablation inductively coupled plasma mass spectroscopy has shown that PP accumulates much less in kidney and is more rapidly excreted than monomeric OX, which is in accord with the

  5. Bis-Porphyrin Racks with Space-Separated Co-Planar Porphyrin Rings

    Directory of Open Access Journals (Sweden)

    Martin R. Johnston

    2001-03-01

    Full Text Available A porphyrin appended norbornenyl building block 8 has been isolated and coupled, using a 1,3-dipolar ACE reaction, to yield bis-porphyrin compounds in which the porphyrin moietes are angled upward relative to the norbornane backbone.

  6. Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins

    KAUST Repository

    Anderson, Carly E.

    2013-09-18

    Two dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide-propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis-para-tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis-ortho-tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time-resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis-ortho-tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins

    KAUST Repository

    Anderson, Carly E.; Vagin, Sergei I.; Hammann, Markus; Zimmermann, Leander; Rieger, Bernhard

    2013-01-01

    Two dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide-propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis-para-tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis-ortho-tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time-resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis-ortho-tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Atezolizumab in platinum-treated locally advanced or metastatic urothelial carcinoma: post-progression outcomes from the phase II IMvigor210 study.

    Science.gov (United States)

    Necchi, A; Joseph, R W; Loriot, Y; Hoffman-Censits, J; Perez-Gracia, J L; Petrylak, D P; Derleth, C L; Tayama, D; Zhu, Q; Ding, B; Kaiser, C; Rosenberg, J E

    2017-12-01

    Conventional criteria for tumor progression may not fully reflect the clinical benefit of immunotherapy or appropriately guide treatment decisions. The phase II IMvigor210 study demonstrated the efficacy and safety of atezolizumab, a programmed death-ligand 1-directed antibody, in patients with platinum-treated locally advanced or metastatic urothelial carcinoma. Patients could continue atezolizumab beyond Response Evaluation Criteria In Solid Tumors (RECIST) v1.1 progression at the investigator's discretion: this analysis assessed post-progression outcomes in these patients. Patients were treated with atezolizumab 1200 mg i.v. every 3 weeks until loss of clinical benefit. Efficacy and safety outcomes in patients who experienced RECIST v1.1 progression and did, or did not, continue atezolizumab were analyzed descriptively. In total, 220 patients who experienced progression from the overall cohort (n = 310) were analyzed: 137 continued atezolizumab for ≥ 1 dose after progression, 19 received other systemic therapy, and 64 received no further systemic therapy. Compared with those who discontinued, patients continuing atezolizumab beyond progression were more likely to have had a baseline Eastern Cooperative Oncology Group performance status of 0 (43.1% versus 31.3%), less likely to have had baseline liver metastases (27.0% versus 41.0%), and more likely to have had an initial response to atezolizumab (responses in 11.7% versus 1.2%). Five patients (3.6%) continuing atezolizumab after progression had subsequent responses compared with baseline measurements. Median post-progression overall survival was 8.6 months in patients continuing atezolizumab, 6.8 months in those receiving another treatment, and 1.2 months in those receiving no further treatment. Atezolizumab exposure-adjusted adverse event frequencies were generally similar before and following progression. In this single-arm study, patients who continued atezolizumab beyond RECIST v1

  9. Porphyrin coordination polymer nanospheres and nanorods

    Science.gov (United States)

    Wang, Zhongchun; Shelnutt, John A.; Medforth, Craig J.

    2012-12-04

    A porphyrin coordination polymer nanostructure comprising a network of pyridyl porphyrin molecules and coordinating metal ions coordinatively bound through the pyridyl groups. In some embodiments, the porphyrins are metalloporphyrins. A variety of nanostructures are formed by the network polymer, including nanospheres, polygonal nanostructures, nanorods, and nanofibers, depending on a variety of factors including coordination metal ion, porphyrin type, metal of the metalloporphyrin, and degree of agitation during nanostructure formation. Reduction of coordinating metal ions may be used to form metal nanoparticles on the coordination polymer nanostructure.

  10. Synthesis and Spectroscopic Characterization of Two Tetrasubstituted Cationic Porphyrin Derivatives

    Directory of Open Access Journals (Sweden)

    Newton M. Barbosa Neto

    2011-07-01

    Full Text Available An imidazolium tetrasubstituted cationic porphyrin derivative (the free base and its Zn(II complex with five-membered heterocyclic groups in the meso-positions were synthesized using microwave irradiation, and the compounds obtained characterized by 1H-NMR and mass spectrometry. We observed that under microwave irradiation the yield is similar to when the synthesis is performed under conventional heating, however, the time required to prepare the porphyrins decreases enormously. In order to investigate the electronic state of these compounds, we employed UV-Vis and fluorescence spectroscopy combined with quantum chemical calculations. The results reveal the presence, in both compounds, of a large number of electronic states involving the association between the Soret and a blue-shifted band. The Soret band in both compounds also shows a considerable solvent dependence. As for emission, these compounds present low quantum yield at room temperature and no solvent influence on the fluorescence spectra was observed.

  11. A new [(1R,2R)-1,2-diaminocyclohexane]platinum(II) complex: formation by nitrate-acetonitrile ligand exchange

    Czech Academy of Sciences Publication Activity Database

    Pažout, R.; Housková, J.; Dušek, Michal; Maixner, J.; Cibulková, J.; Kačer, P.

    2010-01-01

    Roč. 66, Part 10 (2010), m273-m275 ISSN 0108-2701 Institutional research plan: CEZ:AV0Z10100521 Keywords : platinum complexes * structure analysis * disorder * cyclohexane * diamine Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.745, year: 2010

  12. Platinum(II) Complexes of 2-(Dimethylamino)ethylselenolate-Donor-Acceptor Inter-Ligand Interactions as Evident from Experimental and TD-DFT Computational Analysis

    Czech Academy of Sciences Publication Activity Database

    Dey, S.; Jain, V. K.; Knoedler, A.; Kaim, W.; Záliš, Stanislav

    č. 11 (2001), s. 2965-2973 ISSN 1434-1948 R&D Projects: GA MŠk ME 439 Institutional research plan: CEZ:AV0Z4040901 Keywords : platinum * selenium * NMR spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.475, year: 2001

  13. and allylsilane platinum(ii)

    African Journals Online (AJOL)

    a

    literature [1, 2]. The products of these reactions are mainly alkenes and hexamethyldisiloxane. ... NMR spectra were obtained on a Perkin-Elmer P-12A spectrometer. ... Samples of complexes 1a-3 were prepared by literature methods [3, 4].

  14. Light-induced reduction of rhodium(III) and palladium(II) on titanium dioxide dispersions and the selective photochemical separation and recovery of gold(III), platinum(IV), and rhodium(III) in chloride media

    Energy Technology Data Exchange (ETDEWEB)

    Borgarello, E.; Serpone, N.; Emo, G.; Harris, R.; Pelizzetti, E.; Minero, C.

    1986-12-03

    Irradiation of aqueous TiO/sub 2/ dispersions containing palladium(II) or rhodium(III) chloride salts with AM1 simulated sunlight leads to the photoreduction of these metals, which are deposited on the semiconductor particle surface. Oxygen is detrimental to the photoreduction of rhodium(III) but not the photoreduction of palladium(II). However, in both cases the reduction process is most efficient if the solution contains CH/sub 3/OH, which acts to scavenge valence band holes of the illuminated TiO/sub 2/ semiconductor. The selective photoreduction and recovery of precious metals from a dilute solution (as might be found in industrial wastes) have been investigated for a mixture of gold(III), platinum(IV), and rhodium(III) chloride salts as a function of various parameters (pH, presence or absence of O/sub 2/, presence or absence of a hole scavenger, and the concentration of the semiconductor). At pH 0, gold is easily separated from platinum and rhodium. The rate of photoreduction of gold(III) on TiO/sub 2/ is nearly independent of the concentration of the semiconductor, under the experimental conditions employed; the limiting rate is 2.7 x 10/sup -7/ M s/sup -1/. The potential utility of this selective photochemical technique is discussed.

  15. Disproportionation of hydroxylamine by water-soluble iron(III) porphyrinate compounds.

    Science.gov (United States)

    Bari, Sara E; Amorebieta, Valentín T; Gutiérrez, María M; Olabe, José A; Doctorovich, Fabio

    2010-01-01

    The reactions of hydroxylamine (HA) with several water-soluble iron(III) porphyrinate compounds, namely iron(III) meso-tetrakis-(N-ethylpyridinium-2yl)-porphyrinate ([Fe(III)(TEPyP)](5+)), iron(III) meso-tetrakis-(4-sulphonatophenyl)-porphyrinate ([Fe(III)(TPPS)](3-)), and microperoxidase 11 ([Fe(III)(MP11)]) were studied for different [Fe(III)(Porph)]/[HA] ratios, under anaerobic conditions at neutral pH. Efficient catalytic processes leading to the disproportionation of HA by these iron(III) porphyrinates were evidenced for the first time. As a common feature, only N(2) and N(2)O were found as gaseous, nitrogen-containing oxidation products, while NH(3) was the unique reduced species detected. Different N(2)/N(2)O ratios obtained with these three porphyrinates strongly suggest distinctive mechanistic scenarios: while [Fe(III)(TEPyP)](5+) and [Fe(III)(MP11)] formed unknown steady-state porphyrinic intermediates in the presence of HA, [Fe(III)(TPPS)](3-) led to the well characterized soluble intermediate, [Fe(II)(TPPS)NO](4-). Free-radical formation was only evidenced for [Fe(III)(TEPyP)](5+), as a consequence of a metal centered reduction. We discuss the catalytic pathways of HA disproportionation on the basis of the distribution of gaseous products, free radicals formation, the nature of porphyrinic intermediates, the Fe(II)/Fe(III) redox potential, the coordinating capabilities of each complex, and the kinetic analysis. The absence of NO(2)(-) revealed either that no HAO-like activity was operative under our reaction conditions, or that NO(2)(-), if formed, was consumed in the reaction milieu.

  16. Metal-porphyrin interactions. VI. The reactivities of several ferric porphyrin monomers with cyanide compared with ligand reactions of iron and cobalt porphyrins reconstituted with proteins. [25/sup 0/

    Energy Technology Data Exchange (ETDEWEB)

    Hambright, P. (Howard Univ., Washington, DC); Chock, P.B.

    1975-01-01

    A study of the hydrolysis and kinetics and equilibrium behavior of cyanide addition to the monomeric iron(III) complexes of meso, proto and deuteroporphyrin-IX in 2 percent sodium lauryl sulfate--0.1 M tetramethyl ammonium bromide, 25/sup 0/ is reported. The reactivity parameters are compared to reactions of the same Co(II) and Fe(II) porphyrin types reconstituted to myoglobins and hemoglobins.

  17. Adsorption of volatile polonium species on metals in various gas atmospheres. Pt. II. Adsorption of volatile polonium on platinum, silver and palladium

    Energy Technology Data Exchange (ETDEWEB)

    Maugeri, Emilio Andrea; Joerg Neuhausen; Dressler, Rugard; Piguet, David; Voegele, Alexander; Schumann, Dorothea [Paul Scherrer Institut (PSI), Villigen (Switzerland). Lab. for Radiochemistry; Misiak, Ryszard [The Henryk Niewodniczanski Institute of Nuclear Physics, Krakow (Poland); Eichler, Robert [Paul Scherrer Institut (PSI), Villigen (Switzerland). Lab. for Radiochemistry; Bern Univ. (Switzerland). Dept. for Chemistry and Biochemistry

    2016-07-01

    This work presents the results obtained from studying the interaction between polonium compounds formed in different atmospheres and platinum, palladium and silver surfaces obtained by thermochromatography. These results are of crucial importance for the design of cover gas filter systems for lead-bismuth eutectic (LBE)-based nuclear facilities such as accelerator driven systems (ADS). The results obtained from studying the interaction of polonium and platinum under inert atmosphere and reducing atmospheres with and without addition of moisture show that polonium is deposited at temperatures between 993 and 1221 K, with adsorption enthalpies ranging from -235 to -291 kJ mol{sup -1}, indicating a very strong adsorption of the polonium species present on platinum surfaces. The interaction between polonium and silver was investigated using purified inert, reducing and oxidizing carrier gases. Results show a deposition temperature between 867 and 990 K, with adsorption enthalpies ranging from -205 to -234 kJ mol{sup -1}. The interaction of polonium and palladium was studied in purified helium and purified hydrogen. For both conditions a deposition temperature of 1221 K was observed corresponding to an adsorption enthalpy of -340 kJ mol{sup -1}. No highly volatile polonium species was formed at any of the applied experimental conditions.

  18. Porphyrin-based Photocatalytic Nanolithography

    Energy Technology Data Exchange (ETDEWEB)

    Bearinger, J P; Stone, G; Dugan, L C; Dasher, B E; Stockton, C; Conway, J W; Kuenzler, T; Hubbell, J A

    2009-06-08

    Nanoarray fabrication is a multidisciplinary endeavor encompassing materials science, chemical engineering and biology. We form nanoarrays via a new technique, porphyrin-based photocatalytic nanolithography (PCNL). The nanoarrays, with controlled features as small as 200 nm, exhibit regularly ordered patterns and may be appropriate for (a) rapid and parallel proteomic screening of immobilized biomolecules, (b) protein-protein interactions and/or (c) biophysical and molecular biology studies involving spatially dictated ligand placement. We demonstrate protein immobilization utilizing nanoarrays fabricated via PCNL on silicon substrates, where the immobilized proteins are surrounded by a non-fouling polymer background.

  19. Novel drug delivery strategies for porphyrins and porphyrin precursors

    Science.gov (United States)

    Morrow, D. I. J.; Donnelly, R. F.

    2009-06-01

    superficial lesions, such as actinic keratosis. In addition, photodynamic antimicrobial chemotherapy (PACT) is attracting increasing interest for the treatment of infection. However, delivery strategies for topical PDT and PACT are still based on application of rather simplistic cream and solution formulations, with little consideration given to thermodynamics, targeting or the physicochemical properties of the active agent. Purpose-designed dosage forms for topical delivery of aminolevulinic acid or its esters include creams containing penetration enhancers and/or iron chelators, pressure sensitive patches and bioadhesive patches. Such systems aim to enhance drug delivery across the stratum corneum and keratinised debris overlying neoplastic lesions and improve subsequent protoporphyrin IX (PpIX) production. The alternative to using porphyrin precursors is the use of pre-formed photosensitisers. However, owing to their relatively high molecular weights, conventional topical application is not appropriate. Innovative strategies, such as the use of needle-free injections and microneedle arrays, bypass the stratum corneum, enabling rapid and targeted delivery not only porphyrin precursors but also pre-formed photosensitisers. This presentation will review drug delivery work published to date in the fields of PDT and PACT. In addition, the benefits of employing the latest advances in pharmaceutical technology will be highlighted.

  20. Long-lived, charge-shift states in heterometallic, porphyrin-based dendrimers formed via click chemistry.

    Science.gov (United States)

    Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol; Odobel, Fabrice; Harriman, Anthony

    2011-05-26

    A series of multiporphyrin clusters has been synthesized and characterized in which there exists a logical gradient for either energy or electron transfer between the porphyrins. A central free-base porphyrin (FbP), for example, is equipped with peripheral zinc(II) porphyrins (ZnP) which act as ancillary light harvesters and transfer excitation energy to the FbP under visible light illumination. Additional energy-transfer steps occur at the triplet level, and the series is expanded by including magnesium(II) porphyrins and/or tin(IV) porphyrins as chromophores. Light-induced electron transfer is made possible by incorporating a gold(III) porphyrin (AuP(+)) into the array. Although interesting by themselves, these clusters serve as control compounds by which to understand the photophysical processes occurring within a three-stage dendrimer comprising an AuP(+) core, a second layer formed from four FbP units, and an outer layer containing 12 ZnP residues. Here, illumination into a peripheral ZnP leads to highly efficient electronic energy transfer to FbP, followed by charge transfer to the central AuP(+). Charge recombination within the resultant charge-shift state is intercepted by secondary hole transfer to the ZnP, which occurs with a quantum yield of around 20%. The final charge-shift state survives for some microseconds in fluid solution at room temperature.

  1. Panitumumab and pegylated liposomal doxorubicin to platinum-resistant epithelial ovarian cancer with KRAS wild-type: An ongoing, nonrandomized, multicenter, phase II trial

    DEFF Research Database (Denmark)

    Dahl Steffensen, Karina; Waldstrøm, Marianne; Lund, B

    2010-01-01

    , and head and neck cancer. No previous studies have evaluated the effect of panitumumab in OC based on KRAS mutation status. Methods: Eligibility criteria are confirmed stage I-IV primary epithelial ovarian/fallopian/peritoneal cancer patients with progression either during or within 6 months after end...... to a total of 33 patients. At present, 15 patients have been enrolled. The primary endpoint is to investigate the response rate in platinum-resistant, KRAS wild- type OC patients treated with PLD supplemented with panitumumab. Translational research is included as a secondary endpoint and tumor tissue...

  2. Reduction reactions of water soluble cyano-cobalt(III)-porphyrins: Metal versus ligand centered processes

    International Nuclear Information System (INIS)

    Mosseri, S.; Neta, P.; Harriman, A.; Hambright, P.

    1990-01-01

    Reduction reactions of dicyano-cobalt(III)-porphyrins [potential in vivo cyanide scavenger drugs] were studied by radiolytic and electrochemical methods using the water soluble tetrakis(4-sulfonatophenyl)porphyrin (TPPS) and tetrakis(N-methyl-4-pyridyl)porphyrin (TMPyP). For [(CN)2CoIIITPPS]-, reduction occurs stepwise to the CoII, CoI, and finally to the phlorin anion. This behavior is similar to that of the cobalt porphyrins in the absence of cyanide, except that the cyanide ligand shifts the reduction potentials to much more negative values. On the other hand, under radiolytic conditions, [(CN)2CoIIITMPyP]- is reduced on the porphyrin macrocycle by one electron to give the CoIII pi-radical anion, which disproportionates into the initial complex and the two-electron ring reduced CoIII phlorin. The radical anion is also formed by intramolecular electron transfer subsequent to the reaction of CoIITMPyP and cyanide. The results are compared with the chemistry of Vitamin B-12

  3. New porphyrin-polyoxometalate hybrid materials: synthesis, characterization and investigation of catalytic activity in acetylation reactions.

    Science.gov (United States)

    Araghi, Mehdi; Mirkhani, Valiollah; Moghadam, Majid; Tangestaninejad, Shahram; Mohammdpoor-Baltork, Iraj

    2012-10-14

    New hybrid complexes based on covalent interaction between 5,10,15,20-tetrakis(4-aminophenyl)porphyrinatozinc(II) and 5,10,15,20-tetrakis(4-aminophenyl)porphyrinatotin(IV) chloride, and a Lindqvist-type polyoxometalate, Mo(6)O(19)(2-), were prepared. These new porphyrin-polyoxometalate hybrid materials were characterized by (1)H NMR, FT IR and UV-Vis spectroscopic methods and cyclic voltammetry. These spectro- and electrochemical studies provided several spectral data for synthesis of these compounds. Cyclic voltammetry showed the influence of the polyoxometalate on the redox process of the porphyrin ring. The catalytic activity of tin(IV)porphyrin-hexamolybdate hybrid material was investigated in the acetylation of alcohols and phenols with acetic anhydride. The reusability of this catalyst was also investigated.

  4. New porphyrins bearing positively charged peripheral groups linked by a sulfonamide group to meso-tetraphenylporphyrin: interactions with calf thymus DNA.

    Science.gov (United States)

    Manono, Janet; Marzilli, Patricia A; Marzilli, Luigi G

    2009-07-06

    New water-soluble cationic meso-tetraarylporphyrins (TArP, Ar = 4-C(6)H(4)) and some metal derivatives have been synthesized and characterized. One main goal was to assess if N-methylpyridinium (N-Mepy) groups must be directly attached to the porphyrin core for intercalative binding of porphyrins to DNA. The new porphyrins have the general formula, [T(R(2)R(1)NSO(2)Ar)P]X(4/8) (R(1) = CH(3) or H and R(2) = N-Mepy-n-CH(2) with n = 2, 3, or 4; or R(1) = R(2) = Et(3)NCH(2)CH(2)). Interactions of selected porphyrins and metalloporphyrins (Cu(II), Zn(II)) with calf thymus DNA were investigated by visible circular dichroism (CD), absorption, and fluorescence spectroscopies. The DNA-induced changes in the porphyrin Soret region (a positive induced CD feature and, at high DNA concentration, increases in the Soret band and fluorescence intensities) indicate that the new porphyrins interact with DNA in an outside, non-self-stacking binding mode. Several new metalloporphyrins did not increase DNA solution viscosity and thus do not intercalate, confirming the conclusion drawn from spectroscopic studies. Porphyrins known to intercalate typically bear two or more N-Mepy groups directly attached to the porphyrin ring, such as the prototypical meso-tetra(N-Mepy)porphyrin tetracation (TMpyP(4)). The distances between the nitrogens of the N-Mepy group are estimated to be approximately 11 A (cis) and 16 A (trans) for the relatively rigid TMpyP(4). For the new flexible porphyrin, [T(N-Mepy-4-CH(2)(CH(3))NSO(2)Ar)P]Cl(4), the distances between the nitrogens are estimated to be able to span the range from approximately 9 to approximately 25 A. Thus, the N-Mepy groups in the new porphyrins can adopt the same spacing as in known intercalators such as TMpyP(4). The absence of intercalation by the new porphyrins indicates that the propensity for the N-Mepy group to facilitate DNA intercalation of cationic porphyrins requires direct attachment of N-Mepy groups to the porphyrin core.

  5. Stage II recovery behavior of a series of ion-irradiated platinum (gold) alloys as studied by field-ion microscopy. [0. 10, 0. 62, and 4. 0 at. percent Au and pure Pt

    Energy Technology Data Exchange (ETDEWEB)

    Wei, C.Y.; Seidman, D.N.

    1976-11-01

    Direct and visible evidence was obtained for long-range migration of self-interstitial atoms (SIAs) in Stage II of three different ion-irradiated platinum (gold) alloys. Field-ion microscope (FIM) specimens of Pt--0.10, 0.62 and 4.0 at. percent Au alloys were irradiated in-situ with 30-keV W/sup +/ or Pt/sup +/ ions at a tip temperature of 35 to 41 K at 2 x 10/sup -9/ torr. Direct observation of the surfaces of the FIM specimens during isochronal warming experiments to 100 K showed that a flux of SIAs crossed the surfaces of the specimens between 40 to 100 K. The spectrum for each alloy consisted of two recovery peaks (substages II/sub B/ and II/sub C/). The results are explained on the basis of an impurity-delayed diffusion mechanism employing a two-level trapping model. The application of this diffusion model to the isochronal recovery spectra yielded a dissociation enthalpy (DELTAh/sub li-Au//sup diss/) and an effective diffusion coefficient for each substage; for substage II/sub B/ DELTAh/sub li-Au//sup diss/ (II/sub B/) = 0.15 eV and for substage II/sub C/ DELTAh/sub li-Au//sup diss/ (II/sub C/) = 0.24 eV. A series of detailed control experiments was also performed to show that the imaging electric field had not caused the observed long-range migration of SIAs and that the observed effects were not the result of surface artifacts. 14 figures, 6 tables.

  6. Single-step electron transfer on the nanometer scale: ultra-fast charge shift in strongly coupled zinc porphyrin-gold porphyrin dyads.

    Science.gov (United States)

    Fortage, Jérôme; Boixel, Julien; Blart, Errol; Hammarström, Leif; Becker, Hans Christian; Odobel, Fabrice

    2008-01-01

    The synthesis, electrochemical properties, and photoinduced electron transfer processes of a series of three novel zinc(II)-gold(III) bisporphyrin dyads (ZnP--S--AuP(+)) are described. The systems studied consist of two trisaryl porphyrins connected directly in the meso position via an alkyne unit to tert-(phenylenethynylene) or penta(phenylenethynylene) spacers. In these dyads, the estimated center to center interporphyrin separation distance varies from 32 to 45 A. The absorption, emission, and electrochemical data indicate that there are strong electronic interactions between the linked elements, thanks to the direct attachment of the spacer on the porphyrin ring through the alkyne unit. At room temperature in toluene, light excitation of the zinc porphyrin results in almost quantitative formation of the charge shifted state (.+)ZnP--S--AuP(.), whose lifetime is in the order of hundreds of picoseconds. In this solvent, the charge-separated state decays to the ground state through the intermediate population of the zinc porphyrin triplet excited state. Excitation of the gold porphyrin leads instead to rapid energy transfer to the triplet ZnP. In dichloromethane the charge shift reactions are even faster, with time constants down to 2 ps, and may be induced also by excitation of the gold porphyrin. In this latter solvent, the longest charge-shifted lifetime (tau=2.3 ns) was obtained with the penta-(phenylenethynylene) spacer. The charge shift reactions are discussed in terms of bridge-mediated super-exchange mechanisms as electron or hole transfer. These new bis-porphyrin arrays, with strong electronic coupling, represent interesting molecular systems in which extremely fast and efficient long-range photoinduced charge shift occurs over a long distance. The rate constants are two to three orders of magnitude larger than for corresponding ZnP--AuP(+) dyads linked via meso-phenyl groups to oligo-phenyleneethynylene spacers. This study demonstrates the critical

  7. Photoexcited iron porphyrin as biomimetic catalysts

    International Nuclear Information System (INIS)

    Bartocci, C.; Maldotti, A.; Varani, G.; Consiglio Nazionale delle Ricerche, Ferrara

    1996-01-01

    Photoexcited iron porphyrins can be of some interest in both fine and industrial chemistry in view of the preparation of new efficient biomimetic catalysts, working with high selectivity under mild temperature and pressure

  8. Magnetic interactions in iron (III) porphyrin chlorides

    International Nuclear Information System (INIS)

    Ernst, J.; Subramanian, Japyesan; Fuhrhop, J.H.

    1977-01-01

    Intermolecular exchange interactions in iron(III) porphyrin chlorides (porphyrin = OEP, proto, TPP) have been studied by X-ray structure, EPR and magnetic susceptibility studies. The crystal structure of Fe(III)OEP-Cl was found to be different from that of the other two. Different types of exchange broadened EPR-spectra are obtained which are attributable to the arrangement in the crystals. The EPR results correlate well with magnetic susceptibility data. (orig.) [de

  9. Urinary porphyrin excretion in hepatitis C infection

    OpenAIRE

    Vogeser, Michael; Jacob, Karl; Zachoval, Reinhart

    1999-01-01

    A high prevalence of hepatitis C virus infection in porphyria cutanea tarda in some populations suggests a close link between viral hepatitis and alteration of porphyrin metabolism. Moreover, there is evidence of a role of porphyrinopathies in hepatocarcinogenesis. The aim of our study was to obtain data on the prevalence and patterns of heme metabolism alterations in patients with chronic hepatitis C virus infection. Urinary porphyrin excretion was prospectively studied in 100 consecutive ou...

  10. Synthesis and characterization of a new class of glycosylated porphyrins bearing the RGD moiety and their application in photodynamic therapy

    International Nuclear Information System (INIS)

    Chaleix, Vincent

    2003-01-01

    The use of porphyrins and analogues as photosensitisers together with visible light is a new treatment of tumors (photodynamic therapy, PDT). Carbohydrate-substituted porphyrins are in this domain very promising compounds. In addition, it is known that endothelial cells of the neo-vascularisation in tumors express αVβ3 integrin. Extracellular domains of this transmembrane glycoprotein are able to bind components of the extracellular matrix (ECM) and more precisely the sequence Arg-Gly-Asp. With the aim of their utilization in photodynamic therapy of cancers, we describe the synthesis and characterization (UV-Visible, mass, NMR) of new glucosylated porphyrins bearing the RGD moiety. The first synthesised compounds were derived from tritolyl and tri-glucosyl-aryl-porphyrins where the peptidic moiety is linked to the phenyl group by a spacer arm by means of a solid phase reaction.. The second series consists of glucosylated porphyrin derivatives bearing a cyclical unsaturated pentapeptide including RGD sequence, obtained by ring closing metathesis in solid phase. We have also synthesized a dimer in which the two glucosylated porphyrins are linked by the RGD sequence. These compounds produced 1 O 2 and photo-cyto-toxicities against K562 leukemia cell line were favourably compared to Photofrin II R . Due to their sensitising abilities, these compounds are of considerable interest for photodynamic therapy. (author) [fr

  11. Proof of concept for molecular velcro based on the attractive interaction between porphyrin and pyridine containing copolymers

    Directory of Open Access Journals (Sweden)

    M. Sievers

    2018-06-01

    Full Text Available In this short communication, we investigated the synthesis and mixing of porphyrin and pyridine functionalized copolymers as a proof of concept for a velcro-like interaction. A functionalized porphyrin monomer with one polymerizable side chain was synthesized following a rational synthetic pathway. Subsequent copolymerization and careful removal of residual free porphyrin led to poly(n-butyl acrylate-co-5,10,15-triphenyl-20-(3-vinylphenylporphyrin. The immobilized porphyrin was transformed into the corresponding zinc(II complex, which is capable of the coordinative binding of one pyridine moiety. Complete metallation was proven by absorption spectroscopy. 4-Vinylpyridine was immobilized by copolymerization with n-butyl acrylate, too. Via controlled radical polymerization conditions, the molecular weight of poly(n-butyl acrylate-co-4-vinylpyridine was limited to one tenth of the molecular weight of the porphyrin containing copolymer. This large difference in the molecular weight easily allowed identifying the polymers in the mixture of both. With the help of diffusion ordered nuclear magnetic resonance spectroscopy, the complete and temperature-stable precipitation of the porphyrin containing copolymer was observed, proving the expected attractive interaction and supramolecular network formation.

  12. Electron Transport through Porphyrin Molecular Junctions

    Science.gov (United States)

    Zhou, Qi

    The goal of this work is to study the properties that would affect the electron transport through a porphyrin molecular junction. This work contributes to the field of electron transport in molecular junctions in the following 3 aspects. First of all, by carrying out experiments comparing the conductance of the iron (III) porphyrin (protected) and the free base porphyrin (protected), it is confirmed that the molecular energy level broadening and shifting occurs for porphyrin molecules when coupled with the metal electrodes, and this level broadening and shifting plays an important role in the electron transport through molecular junctions. Secondly, by carrying out an in-situ deprotection of the acetyl-protected free base porphyrin molecules, it is found out that the presence of acetyl groups reduces the conductance. Thirdly, by incorporating the Matrix-assisted laser desorption/ionization (MALDI) spectrum and the in-situ deprotection prior to formation of molecular junctions, it allows a more precise understanding of the molecules involved in the formation of molecular junctions, and therefore allows an accurate analysis of the conductance histogram. The molecules are prepared by self-assembly and the junctions are formed using a Scanning Tunneling Microscopy (STM) molecular break junction technique. The porphyrin molecules are characterized by MALDI in solution before self-assembly to a gold/mica substrate. The self-assembled monolayers (SAMs) of porphyrins on gold are characterized by Ultraviolet-visible (UV-Vis) reflection spectroscopy to confirm that the molecules are attached to the substrate. The SAMs are then characterized by Angle-Resolved X-ray photoelectron spectroscopy (ARXPS) to determine the thickness and the average molecular orientation of the molecular layer. The electron transport is measured by conductance-displacement (G-S) experiments under a given bias (-0.4V). The conductance value of a single molecule is identified by a statistical analysis

  13. Synthesis of platinum nanowheels using a bicellar template.

    Science.gov (United States)

    Song, Yujiang; Dorin, Rachel M; Garcia, Robert M; Jiang, Ying-Bing; Wang, Haorong; Li, Peng; Qiu, Yan; van Swol, Frank; Miller, James E; Shelnutt, John A

    2008-09-24

    Disk-like surfactant bicelles provide a unique meso-structured reaction environment for templating the wet-chemical reduction of platinum(II) salt by ascorbic acid to produce platinum nanowheels. The Pt wheels are 496 +/-55 nm in diameter and possess thickened centers and radial dendritic nanosheets (about 2-nm in thickness) culminating in flared dendritic rims. The structural features of the platinum wheels arise from confined growth of platinum within the bilayer that is also limited at edges of the bicelles. The size of CTAB/FC7 bicelles is observed to evolve with the addition of Pt(II) complex and ascorbic acid. Synthetic control is demonstrated by varying the reaction parameters including metal salt concentration, temperature, and total surfactant concentration. This study opens up opportunities for the use of other inhomogeneous soft templates for synthesizing metals, metal alloys, and possibly semiconductors with complex nanostructures.

  14. Ratiometric Fluorescent Detection of Pb2+ by FRET-Based Phthalocyanine-Porphyrin Dyads.

    Science.gov (United States)

    Zhang, Dongli; Zhu, Mengliang; Zhao, Luyang; Zhang, Jinghui; Wang, Kang; Qi, Dongdong; Zhou, Yang; Bian, Yongzhong; Jiang, Jianzhuang

    2017-12-04

    Sensitive and selective detection of Pb 2+ is a very worthwhile endeavor in terms of both human health and environmental protection, as the heavy metal is fairly ubiquitous and highly toxic. In this study, we designed phthalocyanine-porphyrin (Pc-Por) heterodyads, namely, H 2 Pc-α-ZnPor (1) and H 2 Pc-β-ZnPor (2), by connecting a zinc(II) porphyrin moiety to the nonperipheral (α) or peripheral (β) position of a metal-free phthalocyanine moiety. Upon excitation at the porphyrin Soret region (420 nm), both of the dyads exhibited not only a porphyrin emission (605 nm) but also a phthalocyanine emission (ca. 700 nm), indicating the occurrence of intramolecular fluorescence resonance energy transfer (FRET) processes from the porphyrin donor to the phthalocyanine acceptor. The dyads can selectively bind Pb 2+ in the phthalocyanine core leading to a red shift of the phthalocyanine absorption and thus a decrease of spectral overlap between the porphyrin emission and phthalocyanine absorption, which in turn suppresses the intramolecular FRET. In addition, the binding of Pb 2+ can highly quench the emission of phthalocyanine by heavy-metal ion effects. The synergistic coupled functions endow the dyads with remarkable ratiometric fluorescent responses at two distinct wavelengths (F 605 /F 703 for 1 and F 605 /F 700 for 2). The emission intensity ratio increased as a linear function to the concentration of Pb 2+ in the range of 0-4.0 μM, whereas the detection limits were determined to be 3.4 × 10 -9 and 2.2 × 10 -8 M for 1 and 2, respectively. Furthermore, by comparative study of 1 and 2, the effects of distance and relative orientation between Pc and ZnPor fluorophores on the FRET efficiency and sensing performance were highlighted, which is helpful for further optimizing such FRET systems.

  15. Studies of interactions of porphyrins with transfer RNA by high-resolution NMR

    International Nuclear Information System (INIS)

    Birdsall, W.J.; Lehigh Univ., Bethlehem, PA; Anderson, W.R. Jr; Foster, N.

    1989-01-01

    The interactions of tetra-4N-methulpyridyl porphyrin and its zinc (II), copper (II) and manganese (III) complexes with brewer's yeast type V phenylalanine specific tRNA have been evaluated by high-resolution NMR. Differences in chemical shifts have been noted for thre proton resonances in response to the presence of small quantities of the fre base and the zinc and copper complexes. The protons giving rise to these signals are located on bases T54 and psi55, both of which are involved in the primary intraloop and interloop hydroen bonds that hold the D and TpsiC loops together in the tertiary structure. In addition, broadening of specific resonances due to hydrogen bonding protons in the D stem at low ratios of porphyrin to tRNA indicates that the association of porphyrins increases the rate of imino proton exchange. The titration of the tRNA with the manganese (III) complex did not eveal shifts or spcific broadening comparable to the other porpyrins at low ratios. The changes induced in the NMR spectrum of tNA by porphyrins define their site of interaction with the polynucleotide. This site, at the outside of the elbow-bend in the tRNA 'L', is different from the locus of binding in tRNA for other classical DNA intercalators. Furthermore, a new mode of binding may be involved that is neither intercalative nor simply electrostatic. (author). 36 refs.; 4 figs

  16. Concerning the Deactivation of Cobalt(III)-Based Porphyrin and Salen Catalysts in Epoxide/CO 2 Copolymerization

    KAUST Repository

    Xia, Wei

    2015-02-05

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Functioning as active catalysts for propylene oxide (PO) and carbon dioxide copolymerization, cobalt(III)-based salen and porphyrin complexes have drawn great attention owing to their readily modifiable nature and promising catalytic behavior, such as high selectivity for the copolymer formation and good regioselectivity with respect to the polymer microstructure. Both cobalt(III)-salen and porphyrin catalysts have been found to undergo reduction reactions to their corresponding catalytically inactive cobalt(II) species in the presence of propylene oxide, as evidenced by UV/Vis and NMR spectroscopies and X-ray crystallography (for cobalt(II)-salen). Further investigations on a TPPCoCl (TPP=tetraphenylporphyrin) and NaOMe system reveal that such a catalyst reduction is attributed to the presence of alkoxide anions. Kinetic studies of the redox reaction of TPPCoCl with NaOMe suggests a pseudo-first order in cobalt(III)-porphyrin. The addition of a co-catalyst, namely bis(triphenylphosphine)iminium chloride (PPNCl), into the reaction system of cobalt(III)-salen/porphyrin and PO shows no direct stabilizing effect. However, the results of PO/CO2 copolymerization by cobalt(III)-salen/porphyrin with PPNCl suggest a suppressed catalyst reduction. This phenomenon is explained by a rapid transformation of the alkoxide into the carbonate chain end in the course of the polymer formation, greatly shortening the lifetime of the autoreducible PO-ring-opening intermediates, cobalt(III)-salen/porphyrin alkoxides. CO2 saves: The deactivation of cobalt(III)-porphyrin and salen catalysts in propylene oxide/carbon dioxide copolymerization is systematically investigated, revealing a proposed mechanism for the catalyst reduction (see scheme).

  17. Concerning the Deactivation of Cobalt(III)-Based Porphyrin and Salen Catalysts in Epoxide/CO 2 Copolymerization

    KAUST Repository

    Xia, Wei; Salmeia, Khalifah A.; Vagin, Sergei I.; Rieger, Bernhard

    2015-01-01

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Functioning as active catalysts for propylene oxide (PO) and carbon dioxide copolymerization, cobalt(III)-based salen and porphyrin complexes have drawn great attention owing to their readily modifiable nature and promising catalytic behavior, such as high selectivity for the copolymer formation and good regioselectivity with respect to the polymer microstructure. Both cobalt(III)-salen and porphyrin catalysts have been found to undergo reduction reactions to their corresponding catalytically inactive cobalt(II) species in the presence of propylene oxide, as evidenced by UV/Vis and NMR spectroscopies and X-ray crystallography (for cobalt(II)-salen). Further investigations on a TPPCoCl (TPP=tetraphenylporphyrin) and NaOMe system reveal that such a catalyst reduction is attributed to the presence of alkoxide anions. Kinetic studies of the redox reaction of TPPCoCl with NaOMe suggests a pseudo-first order in cobalt(III)-porphyrin. The addition of a co-catalyst, namely bis(triphenylphosphine)iminium chloride (PPNCl), into the reaction system of cobalt(III)-salen/porphyrin and PO shows no direct stabilizing effect. However, the results of PO/CO2 copolymerization by cobalt(III)-salen/porphyrin with PPNCl suggest a suppressed catalyst reduction. This phenomenon is explained by a rapid transformation of the alkoxide into the carbonate chain end in the course of the polymer formation, greatly shortening the lifetime of the autoreducible PO-ring-opening intermediates, cobalt(III)-salen/porphyrin alkoxides. CO2 saves: The deactivation of cobalt(III)-porphyrin and salen catalysts in propylene oxide/carbon dioxide copolymerization is systematically investigated, revealing a proposed mechanism for the catalyst reduction (see scheme).

  18. Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles

    Science.gov (United States)

    Lavado, Andrea S.; Chauhan, Veeren M.; Alhaj Zen, Amer; Giuntini, Francesca; Jones, D. Rhodri E.; Boyle, Ross W.; Beeby, Andrew; Chan, Weng C.; Aylott, Jonathan W.

    2015-08-01

    Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(ii) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures.Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(ii

  19. Phase II study of biweekly cetuximab in combination with irinotecan as second-line treatment in patients with platinum-resistant gastro-oesophageal cancer

    DEFF Research Database (Denmark)

    Schønnemann, K R; Yilmaz, Mette Karen; Bjerregaard, J K

    2012-01-01

    The purpose of this phase II trial was to evaluate the efficacy and safety of cetuximab and irinotecan as second-line treatment in patients with gastro-oesophageal adenocarcinoma.......The purpose of this phase II trial was to evaluate the efficacy and safety of cetuximab and irinotecan as second-line treatment in patients with gastro-oesophageal adenocarcinoma....

  20. Dualism of Sensitivity and Selectivity of Porphyrin Dimers in Electroanalysis.

    Science.gov (United States)

    Lisak, Grzegorz; Tamaki, Takashi; Ogawa, Takuji

    2017-04-04

    This work uncovers the application of porphyrin dimers for the use in electroanalysis, such as potentiometric determination of ions. It also puts in question a current perception of an occurrence of the super-Nernstian response, as a result of the possible dimerization of single porphyrins within an ion-selective membrane. To study that, four various porphyrin dimers were used as ionophores, namely, freebase-freebase, Zn-Zn, Zn-freebase, and freebase-Zn. Since the Zn-freebase and freebase-Zn porphyrin dimers carried both anion- and cation-sensitive porphyrin units, their application in ISEs was utilized in both anion- and cation-sensitive sensors. With respect to the lipophilic salt added, both porphyrins dimers were found anion- and cation-sensitive. This allowed using a single molecule as novel type of versatile ionophore (anion- and cation-selective), simply by varying the membrane composition. All anion-sensitive sensors were perchlorate-sensitive, while the cation-selective sensors were silver-sensitive. The selectivity of the sensors depended primarily on the porphyrin dimers in the ion-selective membrane. Furthermore, the selectivity of cation-sensitive dimer based sensors was found significantly superior to the ones measured for the single porphyrin unit based sensors (precursors of the porphyrin dimers). Thus, the dimerization of single porphyrins may actually be a factor to increase or modulate porphyrin selectivity. Moreover, in the case of cation-sensitive sensors, the selectivity vastly depended on the order of porphyrin units in the dimer. This opens a new approach of regulating and adjusting sensitivity and selectivity of the sensor through the application of complex porphyrin systems with more than one porphyrin units with mix sensitive porphyrins.

  1. Platinum metals in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Zereini, Fathi [Frankfurt Univ. (Germany). Dept. of Environmental Analytical Chemistry; Wiseman, Clare L.S. (ed.) [Toronto Univ. (Canada). School of the Environment

    2015-03-01

    This book contains the five chapters with the following topics: 1. SOURCES OF PGE EMISSIONS ELEMENTS: Sources of Platinum Group Elements (PGE) in the Environment; Impact of Platinum Group Element Emissions from Mining and Production Activities. 2. ANALYTICAL METHODS FOR THE DETERMINATION OF PGE IN BIOLOGICAL AND ENVIRONMENTAL MATRICES: Appraisal of Biosorption for Recovery, Separation and Determination of Platinum, Palladium and Rhodium in Environmental Samples; On the Underestimated Factors Influencing the Accuracy of Determination of Pt and Pd by Electrothermal Atomic Absorption Spectrometry in Road Dust Samples; Application of Solid Sorbents for Enrichment and Separation of Platinum Metal Ions; Voltammetric Analysis of Platinum in Environmental Matrices; Speciation Analysis of Chloroplatinates; Analysis of Platinum Group Elements in Environmental Samples: A Review. 3. OCCURRENCE, CHEMICAL BEHAVIOR AND FATE OF PGE IN THE ENVIRONMENT: Brazilian PGE Research Data Survey on Urban and Roadside Soils; Platinum, Palladium and Rhodium in a Bavarian Roadside Soil; Increase of Platinum Group Element Concentrations in Soils and Airborne Dust During the Period of Vehicular Exhaust Catalysts Introduction; Platinum-Group Elements in Urban Fluvial Bed Sediments-Hawaii; Long-Term Monitoring of Palladium and Platinum Contents in Road Dust of the City of Munich, Germany; Characterization of PGEs and Other Elements in Road Dusts and Airborne Particles in Houston, Texas; Accumulation and Distribution of Pt and Pd in Roadside Dust, Soil and Vegetation in Bulgaria; Increase of the Environmental Pt Concentration in the Metropolitan Area of Mexico City Associated to the Use of Automobile Catalytic Converters; Solubility of Emitted Platinum Group Elements (Pt, Pd and Rh) in Airborne Particulate Matter (PM10) in the Presence of Organic Complexing Agents; The Influence of Anionic Species (Cl{sup -}, NO{sub 3}{sup -}, SO{sub 4}{sup 2-}) on the Transformation and Solubility of Platinum in

  2. Oxygen reduction reaction at MWCNT-modified nanoscale iron(II) tetrasulfophthalocyanine: remarkable performance over platinum and tolerance toward methanol in alkaline medium

    CSIR Research Space (South Africa)

    Fashedemi, OO

    2015-04-01

    Full Text Available A nanoscale iron(II) tetrasulfophthalocyanine (nanoFeTSPc) catalyst obtained by co-ordinating with hexadecyltrimethylammonium bromide and subsequently anchored onto multi-walled carbon nanotubes (MWCNTs) for oxygen reduction reaction (ORR) has been...

  3. Metal porphyrin intercalated reduced graphene oxide nanocomposite utilized for electrocatalytic oxygen reduction

    Directory of Open Access Journals (Sweden)

    Mingyan Wang

    2017-07-01

    Full Text Available In this paper, we report a simple and facile self-assembly method to successfully fabricate cationic metal porphyrin –MtTMPyP (Mt= Cobalt (II, Manganese (III, or Iron (III; TMPyP = 5, 10, 15, 20-tetrakis (N-methylpyridinium-4-yl porphyrin intercalated into the layer of graphene oxide (GO by the cooperative effects of electrostatic and π–π stacking interaction between positively charged metal porphyrin and negatively charged GO sheets. Followed by reduction with hydrazine vapor, a series of novel 2D MtTMPyP/rGOn were fabricated. The as-prepared 2D hybrids were fully characterized and tested as non-noble metal catalysts for oxygen reduction reaction (ORR in an alkaline medium. The MtTMPyP/rGOn hybrids, especially CoTMPyP/rGO5, demonstrated an improved electrocatalytic activity for ORR and a number of exchanged electrons close to 4-electron reaction, increased stability and excellent tolerance to methanol, showing a potential alternative catalyst for ORR in fuel cells and air batteries. Keywords: Metal porphyrin, Reduced graphene oxide, Intercalation, Oxygen reduction reaction, Catalyst

  4. Synthesis of borylated porphyrin and bromo- porphyrin as building blocks for light harvesting antenna molecule

    Science.gov (United States)

    Radzuan, Nuur Haziqah Mohd; Hassan, Nurul Izzaty; Bakar, Muntaz Abu

    2018-04-01

    The building blocks for synthesis of light harvesting antenna which are 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-10,20-diphenylporphyrin, 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-10,20-dihexylporphyrin and 5,10,15,20-tetra-(bromophenyl)porphyrin were synthesized. Borylated porphyrin was synthesized by Suzuki coupling reaction between A2BC bromo-porphyrin and pinacolborane. Whereas 5,10,15,20-tetra-(bromophenyl) porphyrin was synthesized by Lindsey condensation reaction between pyrrole and 4-bromobenzaldehyde. 1H-NMR, 13C-NMR spectroscopy and UV-visible spectroscopy confirmed the successful formation of all compounds.

  5. Novel Antitumor Platinum(II) Conjugates Containing the Nonsteroidal Anti-inflammatory Agent Diclofenac: Synthesis and Dual Mechanisms of Antiproliferative Effects.

    Science.gov (United States)

    Intini, Francesco Paolo; Zajac, Juraj; Novohradsky, Vojtech; Saltarella, Teresa; Pacifico, Concetta; Brabec, Viktor; Natile, Giovanni; Kasparkova, Jana

    2017-02-06

    One concept how to improve anticancer effects of conventional metallodrugs consists in conjugation of these compounds with other biologically (antitumor) active agents, acting by a different mechanism. Here, we present synthesis, biological effects, and mechanisms of action of new Pt(II) derivatives containing one or two nonsteroidal anti-inflammatory diclofenac (DCF) ligands also known for their antitumor effects. The antiproliferative properties of these metallic conjugates show that these compounds are potent and cancer cell selective cytotoxic agents exhibiting activity in cisplatin resistant and the COX-2 positive tumor cell lines. One of these compounds, compound 3, in which DCF molecules are coordinated to Pt(II) through their carboxylic group, is more potent than parental conventional Pt(II) drug cisplatin, free DCF and the congeners of 3 in which DCF ligands are conjugated to Pt(II) via a diamine. The potency of 3 is due to several factors including enhanced internalization that correlates with enhanced DNA binding and cytotoxicity. Mechanistic studies show that 3 combines multiple effects. After its accumulation in cells, it releases Pt(II) drug capable of binding/damaging DNA and DCF ligands, which affect distribution of cells in individual phases of the cell cycle, inhibit glycolysis and lactate transport, collapse mitochondrial membrane potential, and suppress the cellular properties characteristic of metastatic progression.

  6. Balancing Exchange Mixing in Density-Functional Approximations for Iron Porphyrin.

    Science.gov (United States)

    Berryman, Victoria E J; Boyd, Russell J; Johnson, Erin R

    2015-07-14

    Predicting the correct ground-state multiplicity for iron(II) porphyrin, a high-spin quintet, remains a significant challenge for electronic-structure methods, including commonly employed density functionals. An even greater challenge for these methods is correctly predicting favorable binding of O2 to iron(II) porphyrin, due to the open-shell singlet character of the adduct. In this work, the performance of a modest set of contemporary density-functional approximations is assessed and the results interpreted using Bader delocalization indices. It is found that inclusion of greater proportions of Hartree-Fock exchange, in hybrid or range-separated hybrid functionals, has opposing effects; it improves the ability of the functional to identify the ground state but is detrimental to predicting favorable dioxygen binding. Because of the uncomplementary nature of these properties, accurate prediction of both the relative spin-state energies and the O2 binding enthalpy eludes conventional density-functional approximations.

  7. Mechanism of Exciplex Formation Between Cu-Porphyrin and Calf-thymus DNA as Revealed by Saturation Resonance Raman Spectroscopy

    NARCIS (Netherlands)

    Shvedko, A.G.; Kruglik, S.; Kruglik, S.G.; Ermolenkov, V.V.; Turpin, P.Y.; Greve, Jan; Otto, Cornelis

    1999-01-01

    The excited-state complex (exciplex) formation that results from the photoinduced interaction of water-soluble cationic copper(II) 5,10,15,20-tetrakis[4-(N-methylpyridyl)]porphyrin [Cu(TMpy-P4)] with calf-thymus DNA has been studied in detail by resonance Raman (RR) spectroscopy using both ~10 ns

  8. Structure, solution chemistry, antiproliferative actions and protein binding properties of non-conventional platinum(ii) compounds with sulfur and phosphorus donors

    NARCIS (Netherlands)

    Mügge, C.; Rothenburger, C.; Beyer, A.; Görls, H.; Gabbiani, C.; Casini, A.; Michelucci, E.; Landini, I.; Nobili, S.; Mini, E.; Messori, L.; Weigand, W.

    2011-01-01

    Twelve Pt(ii) complexes with cis-PtP2S2 pharmacophores (where P2 refers to two monodentate or one bidentate phosphane ligand and S2 is a dithiolato ligand) were prepared, characterized and evaluated as potential antiproliferative agents. The various compounds were first studied from the structural

  9. Tetradentate Schiff base platinum(II) complexes as new class of phosphorescent materials for high-efficiency and white-light electroluminescent devices.

    Science.gov (United States)

    Che, Chi-Ming; Chan, Siu-Chung; Xiang, Hai-Feng; Chan, Michael C W; Liu, Yu; Wang, Yue

    2004-07-07

    The capabilities of readily prepared and sublimable Pt(II) Schiff base triplet emitters as OLED dopants have been examined; maximum luminous and power efficiencies and luminance of 31 cd A(-1), 14 lm W(-1), and 23,000 cd m(-2), respectively, and white EL (CIE: 0.33, 0.35) by simultaneous host/dopant emission, have been achieved.

  10. Role of pendant proton relays and proton-coupled electron transfer on the hydrogen evolution reaction by nickel hangman porphyrins

    Science.gov (United States)

    Bediako, D. Kwabena; Solis, Brian H.; Dogutan, Dilek K.; Roubelakis, Manolis M.; Maher, Andrew G.; Lee, Chang Hoon; Chambers, Matthew B.; Hammes-Schiffer, Sharon; Nocera, Daniel G.

    2014-01-01

    The hangman motif provides mechanistic insights into the role of pendant proton relays in governing proton-coupled electron transfer (PCET) involved in the hydrogen evolution reaction (HER). We now show improved HER activity of Ni compared with Co hangman porphyrins. Cyclic voltammogram data and simulations, together with computational studies using density functional theory, implicate a shift in electrokinetic zone between Co and Ni hangman porphyrins due to a change in the PCET mechanism. Unlike the Co hangman porphyrin, the Ni hangman porphyrin does not require reduction to the formally metal(0) species before protonation by weak acids in acetonitrile. We conclude that protonation likely occurs at the Ni(I) state followed by reduction, in a stepwise proton transfer–electron transfer pathway. Spectroelectrochemical and computational studies reveal that upon reduction of the Ni(II) compound, the first electron is transferred to a metal-based orbital, whereas the second electron is transferred to a molecular orbital on the porphyrin ring. PMID:25298534

  11. Platinum-group elements

    Science.gov (United States)

    Zientek, Michael L.; Loferski, Patricia J.; Parks, Heather L.; Schulte, Ruth F.; Seal, Robert R.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The platinum-group elements (PGEs)—platinum, palladium, rhodium, ruthenium, iridium, and osmium—are metals that have similar physical and chemical properties and tend to occur together in nature. PGEs are indispensable to many industrial applications but are mined in only a few places. The availability and accessibility of PGEs could be disrupted by economic, environmental, political, and social events. The United States net import reliance as a percentage of apparent consumption is about 90 percent.PGEs have many industrial applications. They are used in catalytic converters to reduce carbon monoxide, hydrocarbon, and nitrous oxide emissions in automobile exhaust. The chemical industry requires platinum or platinum-rhodium alloys to manufacture nitric oxide, which is the raw material used to manufacture explosives, fertilizers, and nitric acid. In the petrochemical industry, platinum-supported catalysts are needed to refine crude oil and to produce aromatic compounds and high-octane gasoline. Alloys of PGEs are exceptionally hard and durable, making them the best known coating for industrial crucibles used in the manufacture of chemicals and synthetic materials. PGEs are used by the glass manufacturing industry in the production of fiberglass and flat-panel and liquid crystal displays. In the electronics industry, PGEs are used in computer hard disks, hybridized integrated circuits, and multilayer ceramic capacitors.Aside from their industrial applications, PGEs are used in such other fields as health, consumer goods, and finance. Platinum, for example, is used in medical implants, such as pacemakers, and PGEs are used in cancer-fighting drugs. Platinum alloys are an ideal choice for jewelry because of their white color, strength, and resistance to tarnish. Platinum, palladium, and rhodium in the form of coins and bars are also used as investment commodities, and various financial instruments based on the value of these PGEs are traded on major exchanges

  12. Helical chirality induction of expanded porphyrin analogues

    Indian Academy of Sciences (India)

    of this figure-eight conformation in relation to the num- ber of π-electrons attracts ... porphyrin moieties.7a–d In this context, application of ... become problematic. Lindsey .... cell. [a]. CD sign (λmax/nm). UV-vis θ/ abs. Ligand of 1st Cotton effect.

  13. Porphyrin formation and its regulation in Arthrobacter

    NARCIS (Netherlands)

    Kortstee, G.J.J.

    1969-01-01

    Porphyrins (tetrapyrroles) are the basic compounds of a number of substances functioning in living organisms as carriers of oxygen (hemoglobin), carriers of electrons (cytochromes) or as a trap for radiant energy (chlorophyll). In these active forms the tetrapyrroles contain a metal and are

  14. Photodynamic Efficiency of Porphyrins Encapsulated into Polysilsesquioxanes

    Czech Academy of Sciences Publication Activity Database

    Rychtáriková, Renata; Šabata, Stanislav; Hetflejš, Jiří; Kuncová, Gabriela

    2012-01-01

    Roč. 66, č. 4 (2012), s. 269-277 ISSN 0366-6352 R&D Projects: GA MŠk ME 892; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40720504 Keywords : porphyrin * immobilization * specific surface area Subject RIV: CC - Organic Chemistry Impact factor: 0.879, year: 2012

  15. Photoconductivity in DNA-Porphyrin Complexes

    Science.gov (United States)

    Myint, Peco; Oxford, Emma; Nyazenga, Collence; Smith, Walter; Qi, Zhengqing; Johnson, A. T.

    2015-03-01

    We have measured the photoconductivity of λ - DNA that is modified by intercalating a porphyrin compound, meso-tetrakis(N-methyl-4-pyridiniumyl)porphyrin (TMPyP), into its base stacks. Intercalation was verified by a red shift and hypochromism of the Soret absorption peak. The DNA/porphyrin strands were then deposited onto oxidized silicon substrates which had been patterned with interdigitated electrodes, and blown dry. Electrical measurements were carried out under nitrogen, using illumination from a 445 nm laser; this wavelength falls within the absorption peak of the DNA/porphyrin complexes. When initially measured under dry nitrogen, the complexes show no photoconductivity or dark conductivity. However, at relative humidities of 30% and above, we do observe dark conductivity, and also photoconductivity that grows with time. Photoconductivity gets larger at higher relative humidity. Remarkably, when the humidity is lowered again, some photoconductivity is now observed, indicating a change that persists for more than 24 hours. It may be that the humidity alters the structure of the DNA, perhaps allowing for better alignment of the bases. This work was supported by NSF Grant BMAT-1306170.

  16. Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles.

    Science.gov (United States)

    Lavado, Andrea S; Chauhan, Veeren M; Zen, Amer Alhaj; Giuntini, Francesca; Jones, D Rhodri E; Boyle, Ross W; Beeby, Andrew; Chan, Weng C; Aylott, Jonathan W

    2015-09-14

    Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(II) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(II) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(II) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures.

  17. Point defects in platinum

    International Nuclear Information System (INIS)

    Piercy, G.R.

    1960-01-01

    An investigation was made of the mobility and types of point defect introduced in platinum by deformation in liquid nitrogen, quenching into water from 1600 o C, or reactor irradiation at 50 o C. In all cases the activation energy for motion of the defect was determined from measurements of electrical resistivity. Measurements of density, hardness, and x-ray line broadening were also made there applicable. These experiments indicated that the principal defects remaining in platinum after irradiation were single vacant lattice sites and after quenching were pairs of vacant lattice sites. Those present after deformation In liquid nitrogen were single vacant lattice sites and another type of defect, perhaps interstitial atoms. (author)

  18. Indirect spectrophotometric determination of trace cyanide with cationic porphyrins.

    Science.gov (United States)

    Ishii, H; Kohata, K

    1991-05-01

    Three highly sensitive methods for the determination of cyanide have been developed, based on the fact that the complexation of silver ions with three cationic porphyrins, 5,10,15,20-tetrakis-(1-methyl-2-pyridinio)porphine [T(2-MPy)P], 5,10,15,20-tetrakis(1-methyl-3-pyridinio)porphine [T(3-MPy)P] and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphine [T(4-MPy)P], in alkaline media is inhibited by cyanide and the decrease in absorbance of the silver(II) complex is proportional to the cyanide concentration. Sensitivities of the procedures developed are 0.133, 0.126 and 0.234 ng/cm(2), respectively for an absorbance of 0.001. Cadmium(II), copper(II), mercury(II), zinc(II), iodide and sulfide interfere with the cyanide determination. One of the proposed methods was applied to the determination of cyanide in waste-water samples, with satisfactory results.

  19. Lipophilic manganese porphyrin crosses blood-brain barrier

    International Nuclear Information System (INIS)

    Nelson, J.A.; Cegnar, J.; Spence, A.M.; Richards, T.L.; Golden, R.N.; Muzi, M.

    1987-01-01

    Most reports on manganese porphyrins as MR imaging contrast agents have focused on a water-soluble compound, Mn-TPPS4. Phototherapy researchers have noted that lipophilic components of hematoporphyrin derivative sensitize normal brain tissue to light-stimulated photodestruction. This observation suggests that a lipophilic paramagnetic agent might be useful for brain contrast enhancement. The current experiments were designed to test the MR imaging effects of a lipid-soluble compound, Mn-mesoporphyrin. An intravenous injection of 0.05 μmoles/kg was administered to rats with a well-characterized astrocytic glioma implanted into the right cerebral hemisphere. MR imaging experiments performed at 2 T on a General Electric CSI-II system revealed T1 relaxation shortening in both normal brain and tumor. Delayed images at 24 hours revealed persistent selective contrast agent enhancement at the gross tumor site

  20. Unusual Circularly Polarized and Aggregation-Induced Near-Infrared Phosphorescence of Helical Platinum(II) Complexes with Tetradentate Salen Ligands.

    Science.gov (United States)

    Song, Jintong; Wang, Man; Zhou, Xiangge; Xiang, Haifeng

    2018-05-17

    A series of chiral and helical Pt II -Salen complexes with 1,1'-binaphthyl linkers were synthesized and characterized. Owing to the restriction of intramolecular motions of central 1,1'-binaphthyls, the complexes exhibit unusual near-infrared aggregation-induced phosphorescence (AIP). The (R)/(S) enantiopure complexes were characterized by X-ray diffraction, circular dichroism spectra, time-dependent density functional theory calculations, and circularly polarized luminescence (CPL). The present work explores the use of tetradentate ligands that can be easily prepared from commercially available enantiopure compounds, and the subsequent preparation of stable CPL-active square planar Pt II complexes with AIP effect that may have interest in many applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Intra-arterial cis-platinum infusion with sodium thiosulfate protection and angiotensin II induced hypertension for treatment of hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Onohara, S.; Kobayashi, H.; Itoh, Y.; Shinohara, S.

    Cis-diamminedichloroplatinum II (CDDP; 52-169 mg/m/sup 2/) mixed with angiotensin II (1.5-10 ..mu..g/min) was infused into the hepatic artery in 33 patients with hepatocellular carcinoma. Simultaneously, sodium thiosulfate (10-50 g) was administered intravenously in order to reduce the systemic toxicity of CDDP. Over 50% reduction in tumor size was obtained in 18 patients (55%). Complete response was achieved in 4 patients (12%). Serum alpha-fetoprotein (AFP) levels decreased by more than 75% in 10 of 18 patients in whom the previous AFP level was more than 200 mg/ml. The one year survival rate was estimated at 61% by the Kaplan-Meier method. Alimentary symptoms (nausea, vomiting) were mild or non-existent in nearly 90 per cent of treatments. Peptic ulcer and abdominal pain were manifested in small numbers. Severe changes in the laboratory data were not observed. High dosage arterial infusion of CDDP and angiotensin II and intravenous injection of sodium thiosulfate was well tolerated and gave effective therapy in hepatocellular carcinoma.

  2. Cationic Zn-Porphyrin Polymer Coated onto CNTs as a Cooperative Catalyst for the Synthesis of Cyclic Carbonates.

    Science.gov (United States)

    Jayakumar, Sanjeevi; Li, He; Chen, Jian; Yang, Qihua

    2018-01-24

    The development of solid catalysts containing multiple active sites that work cooperatively is very attractive for biomimetic catalysis. Herein, we report the synthesis of bifunctional catalysts by supporting cationic porphyrin-based polymers on carbon nanotubes (CNTs) using the direct reaction of 5,10,15,20-tetrakis(4-pyridyl)porphyrin zinc(II), di(1H-imidazol-1-yl)methane, and 1,4-bis(bromomethyl)benzene in the presence of CNTs. The bifunctional catalysts could efficiently catalyze the cycloaddition reaction of epoxides and CO 2 under solvent-free conditions with porphyrin zinc(II) as the Lewis acid site and a bromine anion as a nucleophilic agent working in a cooperative way. Furthermore, a relative amount of porphyrin zinc(II) and quaternary ammonium bromide could be facilely adjusted for facilitating cooperative behavior. The bifunctional catalyst with a TOF up to 2602 h -1 is much more active than the corresponding homogeneous counterpart and is one of the most active heterogeneous catalysts ever reported under cocatalyst-free conditions. The high activity is mainly attributed to the enhanced cooperation effect of the bifunctional catalyst. With a wide substrate scope, the bifunctional catalyst could be stably recycled. This work demonstrates a new approach for the generation of a cooperative activation effect for solid catalysts.

  3. Excited-state absorption in tetrapyridyl porphyrins: comparing real-time and quadratic-response time-dependent density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, David N. [Department of Chemistry; Supercomputing Institute and Chemical Theory Center; University of Minnesota; Minneapolis; USA; Asher, Jason C. [Department of Chemistry; Supercomputing Institute and Chemical Theory Center; University of Minnesota; Minneapolis; USA; Fischer, Sean A. [William R. Wiley Environmental Molecular Sciences Laboratory; Pacific Northwest National Laboratory; P.O. Box 999; Richland; USA; Cramer, Christopher J. [Department of Chemistry; Supercomputing Institute and Chemical Theory Center; University of Minnesota; Minneapolis; USA; Govind, Niranjan [William R. Wiley Environmental Molecular Sciences Laboratory; Pacific Northwest National Laboratory; P.O. Box 999; Richland; USA

    2017-01-01

    Threemeso-substituted tetrapyridyl porphyrins (free base, Ni(ii), and Cu(ii)) were investigated for their optical limiting (OL) capabilities using real-time (RT-), linear-response (LR-), and quadratic-response (QR-) time-dependent density functional theory (TDDFT) methods.

  4. ESI-MS studies of the reactions of novel platinum(II) complexes containing O,O'-chelated acetylacetonate and sulfur ligands with selected model proteins.

    Science.gov (United States)

    Marzo, Tiziano; De Pascali, Sandra A; Gabbiani, Chiara; Fanizzi, Francesco P; Messori, Luigi; Pratesi, Alessandro

    2017-08-01

    A group of mixed-ligand Pt(II) complexes bearing acetylacetonate and sulphur ligands were recently developed in the University of Lecce as a new class of prospective anticancer agents that manifested promising pharma-cological properties in preliminary in vitro and in vivo tests. Though modelled on the basis of cisplatin, these Pt(II) complexes turned out to exhibit a profoundly distinct mode of action as they were found to act mainly on non-genomic targets rather than on DNA. Accordingly, we have explored here their reactions with two representative model proteins through an established ESI-MS procedure with the aim to describe their general interaction mechanism with protein targets. A pronounced reactivity with the tested proteins was indeed documented; the nature of the resulting metallodrug-protein interactions could be characterised in depth in the various cases. Preferential binding to protein targets compared to DNA is supported by independent ICP-OES measurements. The implications of these findings are discussed.

  5. Investigation of cobalt porphyrin doped polymer membrane films for the optical sensing of imidazole and its derivatives

    Directory of Open Access Journals (Sweden)

    Yueyang Tan

    2015-03-01

    Full Text Available A cobalt(II porphyrin was successfully incorporated into polymer membranes for the optical sensing of imidazole and its derivatives. This research has led to a better understanding of the behavior of Co(II porphyrin in solution and in polymeric membranes. In aprotic dichloromethane (DCM, the Co(II tetraphenylporphyrin (CoTPP and Co(II octaethylporphyrin (CoOEP show a sensitive response to imidazole due to the strong ligation of the N-3 on the imidazole ring to the Co(II center, which induces an absorbance change to the Soret band. However, when doped in polymeric films, only the CoTPP exhibits moderate sensitivity towards aqueous imidazole, histamine and histidine. This weakened coordination ability of CoTPP towards imidazole in the polymer films may be due to the coordination of the plasticizer, the impurities from the THF and polymer matrix at the Co(II center. The selectivity of the polymer films towards imidazole over common anions is high. Lifetime of the cobalt(II porphyrin incorporated polymer film was relatively short.

  6. [Renal excretion of total porphyrins and hippuric acid in rats].

    Science.gov (United States)

    Gartzke, J; Burck, D

    1986-09-01

    The amounts of total porphyrins, hippuric acid and creatinine, excreted in urine by adult male Wistar rats, exhibited normal distributions for hippuric acid and creatinine, but a bimodal distribution for total porphyrins. This typical distribution of total porphyrins was still observed when creatinine was used as reference parameter. In biochemical and toxicological experiments in rats, the tested parameters should be therefore be investigated for homogeneity.

  7. Dehalogenation of lindane by a variety of porphyrins and corrins.

    OpenAIRE

    Marks, T S; Allpress, J D; Maule, A

    1989-01-01

    The dehalogenation of lindane by a range of hemoproteins, porphyrins, and corrins has been tested under reducing conditions in the presence of dithiothreitol. In addition, a series of porphyrin-metal ion complexes have been prepared and have also been screened for the capacity to dehalogenate lindane. Hemoglobin, hemin, hematin, and chlorophyll alpha all catalyzed the dehalogenation of lindane, as did all of the corrins tested. The porphyrins which did not contain metal centers--coproporphyri...

  8. Sublethal concentrations of the platinum(II) complex [Pt(O,O'-acac)(gamma-acac)(DMS)] alter the motility and induce anoikis in MCF-7 cells.

    Science.gov (United States)

    Muscella, Antonella; Calabriso, Nadia; Vetrugno, Carla; Urso, Loredana; Fanizzi, Francesco Paolo; De Pascali, Sandra Angelica; Marsigliante, Santo

    2010-07-01

    We showed previously that a new Pt(II) complex ([Pt(O,O'-acac)(gamma-acac)(DMS)]) exerted high and fast apoptotic processes in MCF-7 cells. The objective of this study was to investigate the hypothesis that [Pt(O,O'-acac)(gamma-acac)(DMS)] is also able to exert anoikis and alter the migration ability of MCF-7 cells, and to show some of the signalling events leading to these alterations. Cells were treated with sublethal doses of [Pt(O,O'-acac)(gamma-acac)(DMS)], and the efficiency of colony initiation and anchorage-independent growth was assayed; cell migration was examined by in vitro culture wounding assay. Gelatin zymography for MMP-2 and -9 activities, Western blottings of MMPs, MAPKs, Src, PKC-epsilon and FAK, after [Pt(O,O'-acac)(gamma-acac)(DMS)] treatment, were also performed. Sub-cytotoxic drug concentrations decreased the: (i) anchorage-dependent and -independent growth; (ii) migration ability; and (iii) expression and activity of MMP-2 and MMP-9. [Pt(O,O'-acac)(gamma-acac)(DMS)] provoked the generation of reactive oxygen species (ROS), and the activation of p38MAPK, Src and PKC-epsilon. p38MAPK phosphorylation, cell anoikis and migration due to [Pt(O,O'-acac)(gamma-acac)(DMS)] were blocked by PKC-epsilon inhibition. Furthermore, Src inhibition blocked the [Pt(O,O'-acac)(gamma-acac)(DMS)]-provoked activation of PKC-epsilon, while ROS generation blockage inhibited the activation of Src, and also the decrement of phosphorylated FAK observed in detached [Pt(O,O'-acac)(gamma-acac)(DMS)]-treated cells. Sublethal concentrations of [Pt(O,O'-acac)(gamma-acac)(DMS)] induced anoikis and prevented events leading to metastasis via alterations in cell migration, anchorage independency, stromal interactions and MMP activity. Hence, [Pt(O,O'-acac)(gamma-acac)(DMS)] may be a promising therapeutic agent for preventing growth and metastasis of breast cancer.

  9. Iron porphyrins doped sol-gel glasses: a chemometric study

    International Nuclear Information System (INIS)

    Sacco, Herica C.; Vidoto, Ednalva A.; Nascimento, Otaciro R.

    2000-01-01

    This paper describes the optimized conditions for preparation of iron porphyrin-template doped silica Fe PDS-template) obtained by the sol-gel process. The following porphyrins (Fe P) were used: Fe TFPP Cl, Fe TDCSPP(Na) 4 Cl and Fe TCPP(Na) 4 Cl. Pyridine or 4-phenylimidazole was used as template. The variables that present significant influence on iron porphyrin loading on xerogel were identified and the values that maximize the iron porphyrin loading on xerogel were established . The variables (Solvent volume, fractional factorial design in two levels, 2 5-1 type, generating 16 total experiments for each Fe P studied. (author)

  10. Iron porphyrins doped sol-gel glasses: a chemometric study

    Energy Technology Data Exchange (ETDEWEB)

    Sacco, Herica C.; Vidoto, Ednalva A.; Nascimento, Otaciro R. [Soap Paulo Univ (USP), Sao Carlos (Brazil). Inst. de Fisica; Biazzotto, Juliana C.; Serra, Osvaldo A.; Iamamoto, Yassuko [Sao Paulo Univ. (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras; Ciuffi, Katia J.; Mello, Cesar A.; Oliveira, Daniela C. de [Universidade de Franca , SP (Brazil)

    2000-07-01

    This paper describes the optimized conditions for preparation of iron porphyrin-template doped silica Fe (PDS-template) obtained by the sol-gel process. The following porphyrins (Fe P) were used: Fe TFPP Cl, Fe TDCSPP(Na){sub 4}Cl and Fe TCPP(Na){sub 4} Cl. Pyridine or 4-phenylimidazole was used as template. The variables that present significant influence on iron porphyrin loading on xerogel were identified and the values that maximize the iron porphyrin loading on xerogel were established. The variables Solvent volume, fractional factorial design in two levels, 2{sup 5-1} type, generating 16 total experiments for each Fe P studied. (author)

  11. A Study of Porphyrins in Petroleum Source Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Huseby, Berit

    1997-12-31

    This thesis discusses several aspects of porphyrin geochemistry. Degradation experiments have been performed on the Messel oil shale (Eocene, Germany) to obtain information on porphyrins bound or incorporated into macromolecular structures. Thermal heating of the preextracted kerogen by hydrous pyrolysis was used to study the release of porphyrins and their temperature dependent changes during simulated diagenesis and catagenesis. Selective chemical degradation experiments were performed on the preextracted sediment to get more detailed information about porphyrins that are specifically bound to the macromolecular structures via ester bonds. From the heating experiments, in a separate study, the porphyrin nitrogen content in the generated bitumens was compared to the bulk of organic nitrogen compounds in the fraction. The bulk nitrogen contents in the generated bitumens, the water phase and the residual organic matter was recorded to establish the distribution of nitrogen between the kerogen and product phases. Porphyrins as biomarkers were examined in naturally matured Kimmeridge clay source rocks (Upper Jurassic, Norway), and the use of porphyrins as general indicators of maturity was evaluated. Underlying maturity trends in the biomarker data was investigated by Partial Least Squares analysis. Porphyrin as indicators of depositional conditions was also addressed, where the correlations between the (amounts) abundance of nickel and vanadyl porphyrins were mapped together with other descriptors that are assumed to be indicative of redox depositional conditions. 252 refs., 28 figs., 4 tabs.

  12. A Study of Porphyrins in Petroleum Source Rocks

    Energy Technology Data Exchange (ETDEWEB)

    Huseby, Berit

    1996-12-31

    This thesis discusses several aspects of porphyrin geochemistry. Degradation experiments have been performed on the Messel oil shale (Eocene, Germany) to obtain information on porphyrins bound or incorporated into macromolecular structures. Thermal heating of the preextracted kerogen by hydrous pyrolysis was used to study the release of porphyrins and their temperature dependent changes during simulated diagenesis and catagenesis. Selective chemical degradation experiments were performed on the preextracted sediment to get more detailed information about porphyrins that are specifically bound to the macromolecular structures via ester bonds. From the heating experiments, in a separate study, the porphyrin nitrogen content in the generated bitumens was compared to the bulk of organic nitrogen compounds in the fraction. The bulk nitrogen contents in the generated bitumens, the water phase and the residual organic matter was recorded to establish the distribution of nitrogen between the kerogen and product phases. Porphyrins as biomarkers were examined in naturally matured Kimmeridge clay source rocks (Upper Jurassic, Norway), and the use of porphyrins as general indicators of maturity was evaluated. Underlying maturity trends in the biomarker data was investigated by Partial Least Squares analysis. Porphyrin as indicators of depositional conditions was also addressed, where the correlations between the (amounts) abundance of nickel and vanadyl porphyrins were mapped together with other descriptors that are assumed to be indicative of redox depositional conditions. 252 refs., 28 figs., 4 tabs.

  13. Developments in platinum anticancer drugs

    Science.gov (United States)

    Tylkowski, Bartosz; Jastrząb, Renata; Odani, Akira

    2018-01-01

    Platinum compounds represent one of the great success stories of metals in medicine. Following the unexpected discovery of the anticancer activity of cisplatin (Fig. 1) in 1965 by Prof. Rosenberg [1], a large number of its variants have been prepared and tested for their ability to kill cancer cells and inhibit tumor growth. Although cisplatin has been in use for over four decades, new and more effective platinum-based therapeutics are finally on the horizon. A wide introduction to anticancer studies is given by the authors of the previous chapter. This chapter aims at providing the readers with a comprehensive and in-depth understanding of recent developments of platinum anticancer drugs and to review the state of the art. The chapter is divided into two parts. In the first part we present a historical aspect of platinum and its complexes, while in the second part we give an overview of developments in the field of platinum anticancer agents.

  14. Electrochemical behavior of free-radical derivatives of tetra(4hydroxyl-3,5-di-tert-butylphenyl) porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Pokhodenko, V.D.; Melezhik, A.V.; Platonova, E.P.; Vovk, D.N.

    1984-08-01

    The electrochemical behavior of free-radical derivatives of tetra(4hydroxyl-3,5-di-tert-butylphenyl) porphyrins and their complexes with Mg(II), Zn(II), Ni(II), CU(II), and Pd(II) ions was studied by the methods of voltamperometry, ESR, and spectrophotometry. It was shown that the introduction of free-radical substituents into the porphin macrocycle leads to a substantial decrease in the oxidation and reduction potentials of the complexes. The degree of conjunction of substituents with the porphin macrocycle is estimated according to the difference of the redox potentials of free-radical and quinoid derivatives of metalloporphyrins.

  15. Axial zero-field splitting in mononuclear Co(ii) 2-N substituted N-confused porphyrin: Co(2-NC3H5-21-Y-CH2C6H4CH3-NCTPP)Cl (Y = o, m, p) and Co(2-NC3H5-21-CH2C6H5-NCTPP)Cl.

    Science.gov (United States)

    Lai, Ya-Yuan; Chang, Yu-Chang; Chen, Jyh-Horung; Wang, Shin-Shin; Tung, Jo-Yu

    2016-03-21

    The inner C-benzyl- and C-o-xylyl (or m-xylyl, p-xylyl)-substituted cobalt(ii) complexes of a 2-N-substituted N-confused porphyrin were synthesized from the reaction of 2-NC3H5NCTPPH (1) and CoCl2·6H2O in toluene (or o-xylene, m-xylene, p-xylene). The crystal structures of diamagnetic chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-hydrogen-21-carbaporphyrinato-N,N',N'')zinc(ii) [Zn(2-NC3H5-21-H-NCTPP)Cl; 3 ] and paramagnetic chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-benzyl-21-carbaporphyrinato-N,N',N'')cobalt(ii) [Co(2-NC3H5-21-CH2C6H5NCTPP)Cl; 7], and chloro(2-aza-2-allyl-5,10,15,20-tetraphenyl-21-Y-xylyl-21-carbaporphyrinato-N,N',N'')cobalt(ii) [Co(2-NC3H5-21-Y-CH2C6H4CH3NCTPP)Cl] [Y = o (8), m (9), p (10)] were determined. The coordination sphere around the Zn(2+) (or Co(2+)) ion in 3 (or 7-10) is a distorted tetrahedron (DT). The free energy of activation at the coalescence temperature Tc for the exchange of phenyl ortho protons o-H (26) with o-H (22) in 3 in a CDCl3 solvent is found to be ΔG = 61.4 kJ mol(-1) through (1)H NMR temperature-dependent measurements. The axial zero-field splitting parameter |D| was found to vary from 35.6 cm(-1) in 7 (or 30.7 cm(-1) in 8) to 42.0 cm(-1) in 9 and 46.9 cm(-1) in 10 through paramagnetic susceptibility measurements. The magnitude of |D| can be related to the coordination sphere at the cobalt sites.

  16. Structures and properties of spatially distorted porphyrins

    International Nuclear Information System (INIS)

    Golubchikov, Oleg A; Kuvshinova, Elizaveta M; Pukhovskaya, Svetlana G

    2005-01-01

    The published data on the structures and properties of porphyrins with distorted aromatic macrocycles are generalised and analysed. Data on the crystal structures, spectra and kinetics of formation and dissociation of their coordination derivatives are summarised. It is demonstrated that the distortion of the planar structure of the tetrapyrrole core is one of the most efficient means of controlling spectral, physicochemical and coordination properties of these compounds.

  17. High rectification ratios of Fe-porphyrin molecules on Au facets

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoyu; Wang, Gwo-Ching [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, NY 12180 (United States); Lewis, Kim M., E-mail: lewisk2@rpi.edu [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, NY 12180 (United States)

    2012-09-14

    We report room temperature measurements of current vs. voltage (I-V) from self-assembled Fe porphyrin [Fe(III) 5,15-di[4-(s-acetylthio)phenyl]-10,20-diphenyl porphine] molecular layers formed on annealed gold crystal facets on glass substrates. I-V curves were measured using an atomic force microscope with a conductive platinum tip. We observed a rectifier effect that shows asymmetric I-V curves from a monolayer of molecules. The majority rectification ratios at {+-}1 V obtained from hundreds of I-V lie in between 20 and 200, with the highest up to 9000. This is in contrast to the symmetric I-V curves measured from a few nm thick multilayer molecular islands. We contribute the observed rectification in ultrathin FeP molecular layers from asymmetric Schottky barriers that result from molecules in different bonding strengths to electrodes of gold and platinum. -- Highlights: Black-Right-Pointing-Pointer FeP molecular layers or islands of different thickness were self-assembled on Au. Black-Right-Pointing-Pointer High rectification ratios up to 9000 observed in sub-nm thick FeP molecular layers. Black-Right-Pointing-Pointer Measured current vs. voltage using a conductive AFM tip as one electrode. Black-Right-Pointing-Pointer Observed rectification of symmetric molecules using two different electrodes.

  18. Electron Transfer and Geometric Conversion of Co-NO Moiety in Saddled Porphyrins: Implications for Trigger Role of Tetrapyrrole Distortion.

    Science.gov (United States)

    Tang, Min; Yang, Yan; Zhang, Shaowei; Chen, Jiafu; Zhang, Jian; Zhou, Zaichun; Liu, Qiuhua

    2018-01-02

    The electrons of NO and Co are strongly delocalized in normal {Co-NO} 8 species. In this work, {Co-NO} 8 complexes are induced to convert from (Co II ) +• -NO • to Co III -NO - by a core contraction of 0.06 Å in saddled cobalt(II) porphyrins. This intramolecular electron transfer mechanism indicates that nonplanarity of porphyrin is involved in driving conversion of the NO units from electrophilic NO • as a bent geometry to nucleophilic NO - as a linear geometry. This implies that distortion acts as a trigger in enzymes containing tetrapyrrole. The electronic behaviors of the Co II ions and Co-NO moieties were confirmed by X-ray crystallography, EPR spectroscopy, theoretical calculation, UV-vis and IR spectroscopy, and electrochemistry.

  19. Saddle-shaped porphyrins for dye-sensitized solar cells: new insight into the relationship between nonplanarity and photovoltaic properties.

    Science.gov (United States)

    Shahroosvand, Hashem; Zakavi, Saeed; Sousaraei, Ahmad; Eskandari, Mortaza

    2015-03-07

    We report on the theoretical and experimental studies of the new dye-sensitized solar cells functionalized with 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin zinc(II) complexes bearing 2- and 8-bromo substituents at the β positions. In agreement with the results of TD-DFT calculations, the absorption maxima of di- and octa-brominated Zn(II) complexes, ZnTCPPBr2 and ZnTCPPBr8, exhibited large red-shift compared to that of the non-brominated free base porphyrin (H2TCPP). Furthermore, DFT calculations showed that the higher stabilization of the LUMO levels relative to the HOMO ones makes the HOMO-LUMO gap of the brominated Zn-porphyrins models smaller compared to that of the nonbrominated counterparts, which explains the red shifts of the Soret and Q bands of the brominated compounds. Solar cells containing the new saddle-shaped Zn(II) porphyrins were subjected to analysis in a photovoltaic calibration laboratory to determine their solar to electric energy conversion. In this regard, we found that the overall conversion efficiency of ZnTCPPBr8 adsorbed on TiO2 nanocrystalline films was 5 times as large as that of ZnTCPPBr2 adsorbed on the same films. The effect of the increasing number of Br groups on the photovoltaic performance of the complexes was compared to the results of computational methods using ab initio DFT molecular dynamics simulations and quantum dynamics calculations of electronic relaxation to investigate the interfacial electron transfer (IET) in TCPPBrx/TiO2-anatase nanostructures. Better IET in ZnTCPPBr8 compared to ZnTCPPBr2, and in H2TCPP was evaluated from interfacial electron transfer (IET) simulations. The IET results indicate that electron injection in ZnTCPPBr8-TiO2 (τ = 25 fs) can be up to 5 orders of magnitude faster than ZnTCPPBr2-TiO2 (τ = 125 fs). Both experimental and theoretical results demonstrate that the increase of the number of bromo-substituents at the β-pyrrole positions of the porphyrin macrocycle created a new class of

  20. Extreme electronic modulation of the cofacial porphyrin structural motif.

    Science.gov (United States)

    Fletcher, James T; Therien, Michael J

    2002-04-24

    The synthesis, electrochemistry, and optical spectroscopy of an extensive series of cofacial bis[(porphinato)zinc(II)] compounds are reported. These species were synthesized using sequential palladium-catalyzed cross-coupling and cobalt-mediated [2+2+2] cycloaddition reactions. This modular methodology enables facile control of the nature of macrocycle-to-macrocycle connectivity and allows unprecedented modulation of the redox properties of face-to-face porphyrin species. We report the synthesis of 5,6-bis[(5',5''-10',20'-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (1), 5,6-bis[(2'-5',10',15',20'-tetraphenylporphinato)zinc(II)]indane (2), 5-([2'-5',10',15',20'-tetraphenylporphinato]zinc(II))-6-[(5"-10'',20''-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (3), 5-([2'-5',10',15',20'-tetrakis(trifluoromethyl)porphinato]zinc(II))-6-[(5' '-10' ',20' '-bis[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (4), 5-(2'-5',10',15',20'-[tetrakis(trifluoromethyl)porphinato]zinc(II))-6-[(2''-5'',10'',15'',20''-tetraphenylporphinato)zinc(II)]indane (5), 5,6-bis([2'-5',15'-diphenyl-10',20'-(trifluoromethyl)porphinato]zinc(II))indane (6), and 5,6-bis([2'-5',10',15',20'-tetrakis(trifluoromethyl)porphinato]zinc(II))indane (7); 4-7 define the first examples of cofacial bis[(porphinato)metal] compounds in which sigma-electron-withdrawing perfluoroalkyl groups serve as macrocycle substituents, while 2, 6, and 7 constitute the first such structures that possess a beta-to-beta linkage topology. Cyclic voltammetric studies show that the electrochemically determined HOMO and LUMO energy levels of these cofacial bis(porphinato) complexes can be lowered by 780 and 945 mV, respectively, relative to the archetypal members of this class of compounds; importantly, these orbital energy levels can be modulated over well-defined increments throughout these wide potentiometric domains. Analyses of these cofacial bis

  1. Resonance Raman study on distorted symmetry of porphyrin in ...

    Indian Academy of Sciences (India)

    The resonance Raman (RR) spectra of nickel octaethyl porphyrin, Ni(OEP), ... Nickel ocatethyl porphyrin, Ni(OEP), plays a central role in studies of the molec- ..... [8] T Kitagawa and Y Ozaki, Structure and bonding (Springer-Verlag, Berlin, ... [10] R S Czernuszewicz, K A Macar, Li Xiao-Yuan, J R Kincaid and T G Spiro, J. Am.

  2. Multifunctional porphyrinic materials encapsulated into macronets with photo chemotherapeutic applications

    Energy Technology Data Exchange (ETDEWEB)

    Ion, R. -M.; Fierascu, R. -C.; Dimitriu, I. [Valahia University, Materials Science Department, Targoviste (Romania)

    2008-07-01

    Supramolecidar chemistry is expected to keep a high developing advanced of molecular devices based on multifunctional materials. Porphyrins and their analogues should play a significant role as a consequence of their catalytic, electrocatalytic, photochemical and photoelectrochemical properties. Such molecular materials contain a high porosity with large cavities and galleries that can be functionalization yielding to a desired chirality and structure. The functionalization implies inserting into macrocydic cavity, followed by auto-assembling as columnar aggregates. The obtained cavities are used as host for different molecular guests. H and J-aggregates of some porphyrins are based on the intermolecular interactions of 3-5 Kcal/mol per porphyrin face. The columnar structure formed by porphyrins has a length of 5 to 27 porphyrin unities. In this paper we focused on our own strategy based on coordination chemistry for the design and build-up of supermolecules and supra molecular structures constituted by a porphyrin (TSPPJ and a new and revolutionary method for stabilizing porphyrins (as organic part), by their incapsulation into supports with controlled porosity as macronets (as inorganic parts), obtaining some hybrids materials. Included are also their properties and potential applications. Key words: porphyrins, macronets, photochemotherapy.

  3. The effects of urea, guanidinium chloride and sorbitol on porphyrin ...

    Indian Academy of Sciences (India)

    This paper compares the inhibition effect of porphyrin aggregation in the presence of urea, guanidinium chloride (Gdn) and sorbitol by molecular dynamics simulation. It demonstrates that porphyrin aggregation increases in sorbitol, but decreases towards addition of urea and Gdn. It shows that urea, Gdn and sorbitol can ...

  4. Porphyrin and fullerene-based artificial photosynthetic materials for photovoltaics

    International Nuclear Information System (INIS)

    Imahori, Hiroshi; Kashiwagi, Yukiyasu; Hasobe, Taku; Kimura, Makoto; Hanada, Takeshi; Nishimura, Yoshinobu; Yamazaki, Iwao; Araki, Yasuyuki; Ito, Osamu; Fukuzumi, Shunichi

    2004-01-01

    We have developed artificial photosynthetic systems in which porphyrins and fullerenes are self-assembled as building blocks into nanostructured molecular light-harvesting materials and photovoltaic devices. Multistep electron transfer strategy has been combined with our finding that porphyrin and fullerene systems have small reorganization energies, which are suitable for the construction of light energy conversion systems as well as artificial photosynthetic models. Highly efficient photosynthetic electron transfer reactions have been realized at ITO electrodes modified with self-assembled monolayers of porphyrin oligomers as well as porphyrin-fullerene linked systems. Porphyrin-modified gold nanoclusters have been found to have potential as artificial photosynthetic materials. These results provide basic information for the development of nanostructured artificial photosynthetic systems

  5. Corroles-Porphyrins: A Teamwork for Gas Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Rosamaria Capuano

    2015-04-01

    Full Text Available Porphyrins provide an excellent material for chemical sensors, and they have been used for sensing species both in air and solution. In the gas phase, the broad selectivity of porphyrins is largely dependant on molecular features, such as the metal ion complexed at the core of the aromatic ring and the peripheral substituents. Although these features have been largely exploited to design gas sensor arrays, so far, little attention has been devoted to modify the sensing properties of these macrocycles by variation of the molecular aromatic ring. In this paper, the gas sensing properties of a porphyrin analog, the corrole, are studied in comparison with those of the parent porphyrin. Results show that changes in the aromatic ring have important consequences on the sensitivity and selectivity of the sensors and that porphyrins and corroles can positively cooperate to enhance the performance of sensor arrays.

  6. One-pot synthesis of gold nanoparticles using tetradentate porphyrins

    International Nuclear Information System (INIS)

    Canitez, Fatma K.; Yavuz, Mustafa S.; Ozturk, Ramazan

    2011-01-01

    In this study, the meso-tetra (p-hydroxyphenyl) porphyrin and meso-tetra (m-hydroxyphenyl) porphyrin were coated on to gold nanoparticles (AuNPs) via thioacetate anchors which easily dissociate to form S–Au bonds. 4-tert-butyl phenyl thioacetate-AuNPs were prepared and used as a monodentate passivant to control the size of the tetradentate porphyrin-AuNPs. The porphyrin-coated AuNPs were characterized by UV–Vis, TEM, XRD, and XPS analyses. The tetradentate porphyrin-AuNPs size is within a range of 5–15 nm in diameter with exotic shapes. The plausible network formation for AuNP-p-TPP-SAc and the capping structure of the AuNP-m-TPP-SAc have been suggested.

  7. Self-assembled monolayers of a disulphide-derivatised cobalt-porphyrin on gold

    International Nuclear Information System (INIS)

    Viana, A.S.; Leupold, S.; Montforts, F.-P.; Abrantes, L.M.

    2005-01-01

    A self-assembled monolayer (SAM) of a novel cobalt(II)porphyrin disulphide derivative was prepared on flat gold(1 1 1) electrode. Evidence for surface modification was provided by electrochemical reductive desorption of the monolayer and ellipsometry, consistent with a coverage of 2.5 x 10 -10 mol cm -2 and a thickness of 13 A, respectively. Both results support the presence of SAMs where the molecules share an intermediate position between perpendicular and flat orientation. Scanning tunnelling microscopy have also proven the formation of CoPSS SAMs, however high-resolution images could only be obtained when the CoPSS molecules were diluted in an hexanethiol SAM. The electrocatalytic activity of the surface confined Co-porphyrin was evaluated for the oxygen reduction. Voltammetric data indicate that reaction involves two electrons consistent with the formation of hydrogen peroxide. Under similar experimental conditions the data obtained for an iron-porphyrin analogue points for a full reduction of dioxygen to water

  8. Measurement of urinary porphyrins and porphyrin precursors in Dutch hospital laboratories: a review of quality control over 5 years.

    NARCIS (Netherlands)

    Zuijderhoudt, F.M.; Weykamp, C.W.; Willems, J.L.

    2003-01-01

    BACKGROUND: We evaluated a quality control scheme for the measurement of urinary uroporphyrin, coproporphyrin, total urinary porphyrins and precursors of urinary porphyrins, delta-aminolevulinic acid and porphobilinogen that was performed in The Netherlands during a period of 5 years. METHODS: Six

  9. Spectroscopic evidence of xanthine compounds fluorescence quenching effect on water-soluble porphyrins

    Science.gov (United States)

    Makarska-Bialokoz, Magdalena

    2015-02-01

    The formation of π-stacked complexes between water-soluble porphyrins: 4,4‧,4″,4″‧-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis-(benzoic acid) (H2TCPP), 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (H2TPPS4), 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H2TTMePP), 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphine tetra-p-tosylate (H2TMePyP), the Cu(II) complexes of H2TTMePP and H2TMePyP, as well as chlorophyll a with xanthine, theophylline (1,3-dimethylxanthine) and theobromine (3,7-dimethylxanthine) has been studied analysing their absorption and steady-state fluorescence spectra in aqueous (or acetone in case of chlorophyll a) solution. During titration by the compounds from xanthine group the bathochromic effect in the porphyrin absorption spectra as well as the hypochromicity of the porphyrin Soret maximum can be noticed. The fluorescence quenching effect observed during interactions in the systems examined suggests the process of static quenching. The association and fluorescence quenching constants are of the order of magnitude of 103 - 102 mol-1. The results obtained show that xanthine and its derivatives can quench the fluorescence of the porphyrins according to the number of methyl groups in the molecule of quencher.

  10. LDRD final report on synthesis of shape-and size-controlled platinum and platinum alloy nanostructures on carbon with improved durability.

    Energy Technology Data Exchange (ETDEWEB)

    Shelnutt, John Allen; Garcia, Robert M.; Song, Yujiang; Moreno, Andres M.; Stanis, Ronald J.

    2008-10-01

    This project is aimed to gain added durability by supporting ripening-resistant dendritic platinum and/or platinum-based alloy nanostructures on carbon. We have developed a new synthetic approach suitable for directly supporting dendritic nanostructures on VXC-72 carbon black (CB), single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs). The key of the synthesis is to creating a unique supporting/confining reaction environment by incorporating carbon within lipid bilayer relying on a hydrophobic-hydrophobic interaction. In order to realize size uniformity control over the supported dendritic nanostructures, a fast photocatalytic seeding method based on tin(IV) porphyrins (SnP) developed at Sandia was applied to the synthesis by using SnP-containing liposomes under tungsten light irradiation. For concept approval, one created dendritic platinum nanostructure supported on CB was fabricated into membrane electrode assemblies (MEAs) for durability examination via potential cycling. It appears that carbon supporting is essentially beneficial to an enhanced durability according to our preliminary results.

  11. Transplacental passage of Pt after treatment with the new triamine complex cis-diaminechloro-[2-(diethylamino) ethyl 4-amino-benzoate, N{sup 4}]-chloride platinum (II) monohydrochloride monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Ognio, Emanuela; Lapide, Maddalena [Servizio Modelli Animali, Istituto Nazionale per la Ricerca sul Cancro, Genova (Italy); Chiavarina, Barbara; Viale, Maurizio [U.O. Farmacologia e Neuroscienze, Lab. Farmacologia Tossicologica, Istituto Nazionale per la Ricerca sul Cancro, Lgo R. Benzi, 10, Genova (Italy); Caviglioli, Gabriele [Universita di Genova, Dipartimento di Chimica e Tecnologie Farmaceutiche e Alimentari, Genova (Italy)

    2004-10-01

    Cis-diaminechloro-[2-(diethylamino) ethyl 4-amino-benzoate, N{sup 4}]-chloride platinum (II) monohydrochloride monohydrate (DPR) is a monofunctional Pt triamine complex synthesized starting from cisplatin and procaine hydrochloride, characterized by a good antitumor activity coupled with low toxic effects and able to impair prenatal development of mice but at doses outside or just in the upper range of therapeutic doses. In the present paper the transplacental passage of DPR-derived Pt was investigated in CD1 mice on days 9, 13, 16 and 18 of pregnancy, 24 h after ip administration of 21 mg/kg DPR. For comparison, groups of mice were treated with an equivalent Pt-containing dose of cisplatin (10.7 mg/kg). Similarly to cisplatin, small amounts of Pt were detected in fetuses on day 9. From day 13 of gestation the concentration of DPR- and cisplatin-derived Pt increased up to the highest fetal concentrations detected on day 16. On day 18 the concentration of Pt decreased. Most importantly, on days 13-18 of pregnancy cisplatin-derived Pt was always significantly higher than that assayed after DPR administration. In addition, on day 13 of pregnancy Pt exposure of fetuses was significantly higher when dams were treated with cisplatin (AUC{sub 0.5-24}= 3.40 vs. 4.95 {mu}g.h/g). Finally, it is worth noting that serum decay of Pt after DPR or cisplatin administration in adult female mice was similar with AUC{sub 0.13-2h} s of 7.5 and 6.6 {mu}g.h/ml, respectively. When we determined the concentration of Pt into the main organs of fetuses from dams treated with either DPR or cisplatin on day 18 of gestation, we observed a different organ distribution. In fact, while the concentration of DPR-derived Pt was greater in the heart (1.08{+-}0.30 vs. 0.78{+-}0.35 {mu}g/g, p<0.10), an opposite situation was found in the kidney (0.51{+-}0.20 vs. 0.69{+-}0.22 {mu}g/g, p<0.05). In conclusion, our data show that DPR may pass through the placenta with an efficiency significantly lower than

  12. Quinone-fused porphyrins as contrast agents for photoacoustic imaging

    KAUST Repository

    Banala, Srinivas

    2017-06-27

    Photoacoustic (PA) imaging is an emerging non-invasive diagnostic modality with many potential clinical applications in oncology, rheumatology and the cardiovascular field. For this purpose, there is a high demand for exogenous contrast agents with high absorption coefficients in the optical window for tissue imaging, i.e. the near infrared (NIR) range between 680 and 950 nm. We herein report the photoacoustic properties of quinone-fused porphyrins inserted with different transition metals as new highly promising candidates. These dyes exhibit intense NIR absorption, a lack of fluorescence emission, and PA sensitivity in concentrations below 3 nmol mL. In this context, the highest PA signal was obtained with a Zn(ii) inserted dye. Furthermore, this dye was stable in blood serum and free thiol solution and exhibited negligible cell toxicity. Additionally, the Zn(ii) probe could be detected with an up to 3.2 fold higher PA intensity compared to the clinically most commonly used PA agent, ICG. Thus, further exploration of the \\'quinone-fusing\\' approach to other chromophores may be an efficient way to generate highly potent PA agents that do not fluoresce and shift their absorption into the NIR range.

  13. N-Annulated perylene substituted zinc–porphyrins with different linking modes and electron acceptors for dye sensitized solar cells

    KAUST Repository

    Luo, Jie

    2016-05-03

    Three new N-annulated perylene (NP) substituted porphyrin dyes WW-7-WW-9 with different linking modes and accepting groups were synthesized and applied in Co(ii)/(iii) based dye sensitized solar cells (DSCs). The bay-linked porphyrins WW-7 and WW-8 exhibited moderate power conversion efficiency (PCE = 4.4% and 4.8%, respectively), while the peri-linked porphyrin dye WW-9 showed a PCE up to 9.2% which is slightly lower than that of our reference dye WW-6. Detailed physical measurements (optical and electrochemical), DFT calculations, and photovoltaic characterizations were performed to understand how the structural changes affect their light-harvesting ability, molecular orbital profile, energy level alignment, and eventually the photovoltaic performance. It turned out that the lower efficiencies of the cells based on WW-7 and WW-8 could be ascribed to the weak π-conjugation between the bay-substituted NP and phenylethynyl substituted porphyrin unit. The introduction of a benzothiadiazole acceptor at the anchoring group has induced a significant red shift of the IPCE action spectra of WW-8 and WW-9, by about 90 nm and 50 nm as compared to that of WW-7 and WW-6, respectively. However, less efficient electron injection was observed. Our studies gave some insight into the important role of electronic interactions between different components when one designs a dye for high-efficiency DSCs. © The Royal Society of Chemistry 2016.

  14. N-Annulated perylene substituted zinc–porphyrins with different linking modes and electron acceptors for dye sensitized solar cells

    KAUST Repository

    Luo, Jie; Zhang, Jing; Huang, Kuo-Wei; Qi, Qingbiao; Dong, Shaoqiang; Zhang, Jie; Wang, Peng; Wu, Jishan

    2016-01-01

    Three new N-annulated perylene (NP) substituted porphyrin dyes WW-7-WW-9 with different linking modes and accepting groups were synthesized and applied in Co(ii)/(iii) based dye sensitized solar cells (DSCs). The bay-linked porphyrins WW-7 and WW-8 exhibited moderate power conversion efficiency (PCE = 4.4% and 4.8%, respectively), while the peri-linked porphyrin dye WW-9 showed a PCE up to 9.2% which is slightly lower than that of our reference dye WW-6. Detailed physical measurements (optical and electrochemical), DFT calculations, and photovoltaic characterizations were performed to understand how the structural changes affect their light-harvesting ability, molecular orbital profile, energy level alignment, and eventually the photovoltaic performance. It turned out that the lower efficiencies of the cells based on WW-7 and WW-8 could be ascribed to the weak π-conjugation between the bay-substituted NP and phenylethynyl substituted porphyrin unit. The introduction of a benzothiadiazole acceptor at the anchoring group has induced a significant red shift of the IPCE action spectra of WW-8 and WW-9, by about 90 nm and 50 nm as compared to that of WW-7 and WW-6, respectively. However, less efficient electron injection was observed. Our studies gave some insight into the important role of electronic interactions between different components when one designs a dye for high-efficiency DSCs. © The Royal Society of Chemistry 2016.

  15. Porphyrin-magnetite nanoconjugates for biological imaging

    LENUS (Irish Health Repository)

    Nowostawska, Malgorzata

    2011-04-08

    Abstract Background The use of silica coated magnetic nanoparticles as contrast agents has resulted in the production of highly stable, non-toxic solutions that can be manipulated via an external magnetic field. As a result, the interaction of these nanocomposites with cells is of vital importance in understanding their behaviour and biocompatibility. Here we report the preparation, characterisation and potential application of new "two-in-one" magnetic fluorescent nanocomposites composed of silica-coated magnetite nanoparticles covalently linked to a porphyrin moiety. Method The experiments were performed by administering porphyrin functionalised silica-coated magnetite nanoparticles to THP-1 cells, a human acute monocytic leukaemia cell line. Cells were cultured in RPMI 1640 medium with 25 mM HEPES supplemented with heat-inactivated foetal bovine serum (FBS). Results We have synthesised, characterised and analysed in vitro, a new multimodal (magnetic and fluorescent) porphyrin magnetic nanoparticle composite (PMNC). Initial co-incubation experiments performed with THP-1 macrophage cells were promising; however the PMNC photobleached under confocal microscopy study. β-mercaptoethanol (β-ME) was employed to counteract this problem and resulted not only in enhanced fluorescence emission, but also allowed for elongated imaging and increased exposure times of the PMNC in a cellular environment. Conclusion Our experiments have demonstrated that β-ME visibly enhances the emission intensity. No deleterious effects to the cells were witnessed upon co-incubation with β-ME alone and no increases in background fluorescence were recorded. These results should present an interest for further development of in vitro biological imaging techniques.

  16. Porphyrin Protonation Studied by Magnetic Circular Dichroism

    Czech Academy of Sciences Publication Activity Database

    Štěpánek, Petr; Andrushchenko, Valery; Ruud, K.; Bouř, Petr

    2012-01-01

    Roč. 116, č. 1 (2012), s. 778-783 ISSN 1089-5639 R&D Projects: GA ČR GAP208/11/0105; GA ČR GA203/09/2037; GA ČR GAP208/10/0559; GA MŠk(CZ) LH11033 Institutional research plan: CEZ:AV0Z40550506 Keywords : magnetic circular dichroism ( MCD ) * TPPS * spectra simulations * porphyrin protonation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.771, year: 2012

  17. Valence electronic properties of porphyrin derivatives.

    Science.gov (United States)

    Stenuit, G; Castellarin-Cudia, C; Plekan, O; Feyer, V; Prince, K C; Goldoni, A; Umari, P

    2010-09-28

    We present a combined experimental and theoretical investigation of the valence electronic structure of porphyrin-derived molecules. The valence photoemission spectra of the free-base tetraphenylporphyrin and of the octaethylporphyrin molecule were measured using synchrotron radiation and compared with theoretical spectra calculated using the GW method and the density-functional method within the generalized gradient approximation. Only the GW results could reproduce the experimental data. We found that the contribution to the orbital energies due to electronic correlations has the same linear behavior in both molecules, with larger deviations in the vicinity of the HOMO level. This shows the importance of adequate treatment of electronic correlations in these organic systems.

  18. Redeposition of electrochemically dissolved platinum as nanoparticles on carbon

    DEFF Research Database (Denmark)

    Norgaard, C. F.; Stamatin, S. N.; Skou, E. M.

    2014-01-01

    communication reports a simple chemical method for reprecipitating platinum as nanoparticles of reasonable particle size on a carbon substrate without intermediary separation and handling of solid platinum salt. After electrochemical dissolution, platinum was reprecipitated using a polyol based method. Platinum...

  19. Preparation and characterization of platinum(II) and (IV) complexes of 1,3-diaminepropane and 1,4-diaminebutane: circumvention of cisplatin resistance and DNA interstrand cross-link formation in CH1cisR ovarian tumor cells.

    Science.gov (United States)

    Alvarez-Valdés, Amparo; Pérez, José Manuel; López-Solera, Isabel; Lannegrand, Raúl; Continente, José Manuel; Amo-Ochoa, Pilar; Camazón, María José; Solans, Xavier; Font-Bardía, Mercè; Navarro-Ranninger, Carmen

    2002-04-25

    The reaction of Pt(dimethyl sulfoxide)(2)CBDCA (CBDCA = 1,1-cyclobutanedicarboxylate) with 1,4-diaminebutane and 1,3-diaminepropane ligands yields, under certain conditions, new [Pt(diamine)(2)]CBDCA complexes (1a,b), where the CBDCA ligand has been removed from the coordination sphere of the platinum atom by the diamine ligand, instead of forming the expected [Pt(diamine)CBDCA] complexes (1'a,b). The structure of complexes 1a and 1'b was solved by X-ray diffraction. Complex 1a crystallizes in the orthorhombic system, in the noncentrosymmetric C222 space group, with unit cell parameters: a = 20.053(2) A; b = 8.655(2) A, c = 5.711(3) A; V = 991.2(6) A(3); delta (calcd) = 1.627 mg/m(3); and R = 0.050. The Pt atom displays an unexpected distorted tetrahedral coordination with a N-Pt-N inner bond angle equal to 81(2) degrees for N atoms of the same 1,3-propanediamine ligand and a N-Pt-N bond angle for different ligands equal to 135.4(9) degrees. Complex 1'b crystallizes in the monoclinic system, in the centrosymmetric P2(1)/c space group, with unit cell parameters: a = 6.007(2) A; b = 15.336(4) A, c = 13.232(5) A; beta = 101.90(3) degrees; V = 1192.8(7) A(3); delta (calcd) = 2.369 mg/m(3); and R = 0.067. Cytotoxicity data show that of all the synthesized compounds, only complexes 1'a and 1'b exhibit remarkable cytotoxic properties. Thus, in contrast with carboplatin (cis-diammine-1,1-cyclobutane dicarboxilatoplatinum(II)), compounds 1'a and 1'b, which also contain the CBDCA ligand, are able to circumvent cisplatin (cis-diamminedichloroplatinum(II)) resistance in several tumor cells. Moreover, after 24 h of incubation of CH1cisR ovarian tumor cells with 10 microM of compounds 1'a and 1'b, the level of DNA interstrand cross-links (ICLs) induced by compounds 1'a and 1'b is 3.3 and 3.8 times higher, respectively, than that of carboplatin and 3.5 and 4.0 times higher, respectively, than that of cisplatin. Interestingly, under the same conditions, the intracellular

  20. Porphyrin Interactions with Wild Type and Mutant Mouse Ferrochelatase

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Gloria C.; Franco, Ricardo; Lu, Yi; Ma, Jian-Guo; Shelnutt, John A.

    1999-05-19

    Ferrochelatase (EC 4.99.1.1), the terminal enzyme of the heme biosynthetic pathway, catalyzes Fe2+ chelation into protoporphyrin IX. Resonance Raman and W-visible absorbance spectroscopes of wild type and engineered variants of murine ferrochelatase were used to examine the proposed structural mechanism for iron insertion into protoporphyrin by ferrochelatase. The recombinant variants (i.e., H207N and E287Q) are enzymes in which the conserved amino acids histidine-207 and glutamate-287 of murine ferrochelatase were substituted with asparagine and glutamine, respectively. Both of these residues are at the active site of the enzyme as deduced from the Bacillus subtilis ferrochelatase three-dimensional structure. Addition of free base or metalated porphyrins to wild type ferrochelatase and H207N variant yields a quasi 1:1 complex, possibly a monomeric protein-bound species. In contrast, the addition of porphyrin (either free base or metalated) to E287Q is sub-stoichiometric, as this variant retains bound porphyrin in the active site during isolation and purification. The specificity of porphyrin binding is confirmed by the narrowing of the structure-sensitive resonance Raman lines and the vinyl vibrational mode. Resonance Raman spectra of free base and metalated porphyrins bound to the wild type ferrochelatase indicate a nonplanar distortion of the porphyrin macrocycle, although the magnitude of the distortion cannot be determined without first defining the specific type of deformation. Significantly, the extent of the nonplanar distortion varies in the case of H207N- and E287Q-bound porphyrins. In fact, resonance Raman spectral decomposition indicates a homogeneous ruffled distortion for the nickel protoporphyrin bound to the wild type ferrochelatase, whereas both a planar and ruffled conformations are present for the H207N-bound porphyrin. Perhaps more revealing is the unusual resonance , 3 Raman spectrum of the endogenous E287Q-bound porphyrin, which has

  1. Tripodal polyphosphine ligands as inductors of chelate ring-opening processes in mononuclear palladium(II) and platinum(II) compounds. The X-ray crystal structure of two derivatives containing dangling phosphorus.

    Science.gov (United States)

    Fernández-Anca, Damián; García-Seijo, M Inés; García-Fernández, M Esther

    2010-03-07

    The reaction of NP(3) (tris[2-(diphenylphosphino)ethyl]amine and PP(3) (tris[2-(diphenylphosphino)ethyl]phosphine) with the five-coordinate complexes [PdCl(NP(3))]Cl (1) and [MX(PP(3))]X [M = Pd: X = Cl(2), Br(3), I(4); M = Pt: X = Cl(5), Br(6), I(7)], respectively, followed by (31)P{(1)H}NMR when X = Cl, led to the formation of unprecedented four-coordinate halides in a 1 : 2 metal to ligand ratio, [M(AP(3))(2)]X(2) [A = N, M = Pd: X = Cl(8); A = P, M = Pd: X = Cl(9), Br(10), I(11); A = P, M = Pt: X = Cl(12), Br(13), I (14)], containing reactive dangling phosphorus. Given the non characterised precursors [M(ONO(2))(PP(3))](NO(3))], the interaction between the heteronuclear species [MAg(NO(3))(3)(PP(3))] [M = Pd(15), Pt(16)] and PP(3) was explored. It was found that the addition of 1 equivalent of phosphine afforded [MAg(NO(3))(PP(3))(2)](NO(3))(2) [M = Pd(15*), Pt(16*)] containing Ag(I) bound to two dangling phosphorus while the reaction with 2 equivalents led to the complexes [M(PP(3))(2)](NO(3))(2) [M = Pd (17), Pt (18)] in coexistence with [Ag(2)(mu-PP(3))(2)](NO(3))(2). The fate of Ag(I) on the reaction of the mixed metal compounds with excess PP(3) consisted of preventing dissociation, observed in solution for halides, and acting as an assistant for crystallization. Colourless single crystals of 18 and 10, studied by X-ray diffraction, were afforded by reaction of 16 with 4 equivalents of PP(3) and from solutions of 10 in chloroform coexisting with red crystals of 3, respectively. The structures revealed the presence of dications [M(PP(3))(2)](2+) that show two five-membered chelate rings to M(II) in a square-planar arrangement and four uncoordinated phosphine arms with the counter anions being symmetrically placed at 4.431 (Br(-)) and 13.823 (NO(3)(-)) A from M(II) above and below its coordination, MP(4), plane. Complexes 9 and 12 were shown to undergo an interesting reactivity in solution versus group 11 monocations. The reactions consisted of conversions

  2. Studies on the Synthesis, Photophysical and Biological Evaluation of Some Unsymmetrical Meso-Tetrasubstituted Phenyl Porphyrins

    Directory of Open Access Journals (Sweden)

    Rica Boscencu

    2017-10-01

    Full Text Available Abstract: We designed three unsymmetrical meso-tetrasubstituted phenyl porphyrins for further development as theranostic agents for cancer photodynamic therapy (PDT: 5-(4-hydroxy-3-methoxyphenyl-10,15,20-tris-(4-acetoxy-3-methoxyphenylporphyrin (P2.2, Zn(II-5-(4-hydroxy-3-methoxyphenyl-10,15,20-tris-(4-acetoxy-3-methoxyphenylporphyrin (Zn(II2.2 and Cu(II-5-(4-hydroxy-3-methoxyphenyl-10,15,20-tris-(4-acetoxy-3-methoxyphenylporphyrin (Cu(II2.2. The porphyrinic compounds were synthesized and their structures were confirmed by elemental analysis, FT-IR, UV-Vis, EPR and NMR. The compounds had a good solubility in polar/nonpolar media. P2.2 and, to a lesser extent, Zn(II2.2 were fluorescent, albeit with low fluoresence quantum yields. P2.2 and Zn(II2.2 exhibited PDT-acceptable values of singlet oxygen generation. A “dark” cytotoxicity study was performed using cells that are relevant for the tumor niche (HT-29 colon carcinoma cells and L929 fibroblasts and for blood (peripheral mononuclear cells. Cellular uptake of fluorescent compounds, cell viability/proliferation and death were evaluated. P2.2 was highlighted as a promising theranostic agent for PDT in solid tumors considering that P2.2 generated PDT-acceptable singlet oxygen yields, accumulated into tumor cells and less in blood cells, exhibited good fluorescence within cells for imagistic detection, and had no significant cytotoxicity in vitro against tumor and normal cells. Complexing of P2.2 with Zn(II or Cu(II altered several of its PDT-relevant properties. These are consistent arguments for further developing P2.2 in animal models of solid tumors for in vivo PDT.

  3. A multicenter, non-randomized, phase II study of docetaxel and carboplatin administered every 3 weeks as second line chemotherapy in patients with first relapse of platinum sensitive epithelial ovarian, peritoneal or fallopian tube cancer

    DEFF Research Database (Denmark)

    Wang, Yun; Herrstedt, Jørn; Havsteen, Hanne

    2014-01-01

    of 398 cycles were given. Grade 3/4 neutropenia was seen in 80% (59 of 74) patients with an incidence of febrile neutropenia of 16%. Grade 2/3 sensory peripheral neuropathy occurred in 7% of patients, but no grade 4 sensory peripheral neuropathy was observed. Sixty patients were evaluable for response...... of platinum-sensitive ovarian, peritoneal and Fallopian tube cancer. The major toxicity was neutropenia, while the frequency of peripheral neuropathy was low.......BACKGROUND: In patients with ovarian cancer relapsing at least 6 months after end of primary treatment, the addition of paclitaxel to platinum treatment has been shown to improve survival but at the cost of significant neuropathy. In the first line setting, the carboplatin-docetaxel combination...

  4. A phase II trial of fixed-dosed rate gemcitabine in platinum-resistant ovarian cancer: a GEICO (Grupo Español de Investigación en Cáncer de Ovario) Trial.

    Science.gov (United States)

    Ojeda Gonzalez, Belen; Gonzalez Martin, Antonio; Bover Barcelo, Isabel; Fabregat i Mayol, Xavier; Mellado, Begoña; Rubio Perez, María Jesus; Alonso Carrion, Lorenzo; Casado Herraez, Antonio; Calvo Garcia, Elisa; Churruca Galaz, Cristina; Arcusa Lanza, Angels; Herrero Ibañez, Ana; Adrover Cebrian, Encarna; Poveda Velasco, Andres

    2008-10-01

    Gemcitabine has well-recognized activity in the treatment of ovarian cancer. Fixed-dose rate (FDR) delivery has been proposed as a more rationale way to administer gemcitabine, to avoid saturation of the enzyme that catalyzes its intracellular transformation into the active metabolites, difluorodeoxycitidine biphosphate, and triphosphate. Our aim was to assess clinical activity of gemcitabine delivered by FDR infusion in patients with platinum resistant ovarian cancer. Patients with platinum-resistant ovarian cancer received gemcitabine 1000 mg/m(2) over 120 minutes on days 1 and 8 of each cycle. Cycles were repeated every 3 weeks, and up to 6 cycles were delivered. Forty-eight patients were included in the study. Among 41 patients evaluable for response, 9 clinical responses (1 complete response and 8 partial responses) were observed, achieving a global response rate of 22%. Grade 3 to 4 hematological toxicity consisted of anemia (15% of patients), neutropenia (24%), and thrombopenia (10%). One patient died due to septic shock. The main grade 3 to 4 nonhematological toxicity was asthenia (7 patients, 17%). Activity of gemcitabine administered by FDR infusion in patients with platinum-resistant ovarian cancer seems similar to that achieved using 30-minute infusions, with higher toxicity.

  5. Spectroscopic and biological approach in the characterization of a novel 14-membered [N4] macrocyclic ligand and its palladium(II), platinum(II), ruthenium(III) and iridium(III) complexes.

    Science.gov (United States)

    Rani, Soni; Kumar, Sumit; Chandra, Sulekh

    2014-01-24

    A novel, tetradentate nitrogen donor [N4] macrocyclic ligand, i.e. 3,5,14,16-tetramethyl-2,6,13,17-tetraazatricyclo[12,0,0(7-12)] cosa-1(22),2,5,7,9,11,13,16,18,20-decaene(L), has been synthesized and characterized by elemental analyses, IR, Mass, and (1)H NMR spectral studies. Complexes of Pd(II), Pt(II), Ru(III) and Ir(III) have been prepared and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral and thermal studies. On the basis of molar conductance the complexes may be formulated as [PdL]Cl2, [PtL]Cl2, [Ru(L)Cl2]Cl and [Ir(L)Cl2]Cl. The complexes are insoluble in most common solvents, including water, ethanol, carbon tetrachloride and acetonitrile, but soluble in DMF/DMSO. The value of magnetic moment indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moment corresponding to one unpaired electron. The magnetic moment of Ru(III) complex is 1.73 B.M. at room temperature. The antimicrobial activities of ligand and its complexes have been screened in vitro, as growth inhibiting agents. The antifungal and antibacterial screening were carried out using Food Poison and Disc Diffusion Method against plant pathogenic fungi and bacteria Alternaria porri, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa respectively. The compounds were dissolved in DMSO to get the required solutions. The required medium used for these activities was PDA and nutrient agar. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Spectroscopic and biological approach in the characterization of a novel 14-membered [N4] macrocyclic ligand and its Palladium(II), Platinum(II), Ruthenium(III) and Iridium(III) complexes

    Science.gov (United States)

    Rani, Soni; Kumar, Sumit; Chandra, Sulekh

    2014-01-01

    A novel, tetradentate nitrogen donor [N4] macrocyclic ligand, i.e. 3,5,14,16-tetramethyl-2,6,13,17-tetraazatricyclo[12,0,07-12] cosa-1(22),2,5,7,9,11,13,16,18,20-decaene(L), has been synthesized and characterized by elemental analyses, IR, Mass, and 1H NMR spectral studies. Complexes of Pd(II), Pt(II), Ru(III) and Ir(III) have been prepared and characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, Mass, electronic spectral and thermal studies. On the basis of molar conductance the complexes may be formulated as [PdL]Cl2, [PtL]Cl2, [Ru(L)Cl2]Cl and [Ir(L)Cl2]Cl. The complexes are insoluble in most common solvents, including water, ethanol, carbon tetrachloride and acetonitrile, but soluble in DMF/DMSO. The value of magnetic moment indicates that all the complexes are diamagnetic except Ru(III) complex which shows magnetic moment corresponding to one unpaired electron. The magnetic moment of Ru(III) complex is 1.73 B.M. at room temperature. The antimicrobial activities of ligand and its complexes have been screened in vitro, as growth inhibiting agents. The antifungal and antibacterial screening were carried out using Food Poison and Disc Diffusion Method against plant pathogenic fungi and bacteria Alternaria porri, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa respectively. The compounds were dissolved in DMSO to get the required solutions. The required medium used for these activities was PDA and nutrient agar.

  7. Relativistic effects in iron-, ruthenium-, and osmium porphyrins

    International Nuclear Information System (INIS)

    Liao Mengsheng; Scheiner, Steve

    2002-01-01

    Nonrelativistic and relativistic DFT calculations are performed on four-coordinate metal porphyrins MP and their six-coordinate adducts MP(py) 2 and MP(py)(CO) (py=pyridine) with M=Fe, Ru, and Os. The electronic structures of the MPs are investigated by considering all possible low-lying states with different configurations of nd-electrons. FeP and OsP have a 3 A 2g ground state, while this state is nearly degenerate with 3 E g for RuP. Without relativistic corrections, the ground states of both RuP and OsP would be 3 E g . For the six-coordinate adducts with py and CO, the strong-field axial ligands raise the energy of the M d z 2 -orbital, thereby making the M II ion diamagnetic. The calculated redox properties of MP(py) 2 and MP(py)(CO) are in agreement with experiment. The difference between RuP(py)(CO) and OsP(py)(CO), in terms of site of oxidation, is due to relativistic effects

  8. The coordination and atom transfer chemistry of titanium porphyrin complexes

    Energy Technology Data Exchange (ETDEWEB)

    Hays, James Allen [Iowa State Univ., Ames, IA (United States)

    1993-11-05

    Preparation, characterization, and reactivity of (η2- alkyne)(meso-tetratolylpoprphrinato)titanium(II) complexes are described, along with inetermetal oxygen atom transfer reactions involving Ti(IV) and Ti(III) porphyrin complexes. The η2- alkyne complexes are prepared by reaction of (TTP)TiCl2 with LiAlH4 in presence of alkyne. Structure of (OEP)Ti(η2-Ph-C≡C-Ph) (OEP=octaethylporphryin) was determined by XRD. The compounds undergo simple substitution to displace the alkyne and produce doubly substituted complexes. Structure of (TTP)Ti(4-picoline)2 was also determined by XRD. Reaction of (TTP)Ti=O with (OEP)Ti-Cl yields intermetal O/Cl exchange, which is a one-electron redox process mediated by O atom transfer. Also a zero-electron redox process mediated by atom transfer is observed when (TTP)TiCl2 is reacted with (OEP)Ti=O.

  9. Synthesis, spectroscopy and photosensitizing properties of hydroxynitrophenyl porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Maestrin, Ana Paula J.; Tedesco, Antonio Claudio; Neri, Claudio R.; Gandini, Maria Elisa F.; Serra, Osvaldo A.; Iamamoto, Yassuko [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Inst. de Quimica]. E-mail: osaserra@usp.br

    2004-10-01

    The hydroxynitrophenyl porphyrins, 5,10,15,20-tetrakis(2-hydroxy-5-nitrophenyl)porphyrin and 5-mono(carboxyphenyl)-10,15,20-tris(2-hydroxy-5-nitrophenyl)porphyrin described in this work were prepared through Adler's method. These compounds were characterized by {sup 1}H NMR and light absorption and emission spectroscopy in the visible region. In order to demonstrate the involvement of {sup 1}O{sub 2} production, the uric (UA) acid test was carried out, which considers the decrease in the absorbance of UA at 293 nm following laser light irradiation of a solution containing UA and a photosensitizer. The results obtained demonstrate that these hydroxynitrophenyl porphyrins can be considered as promising photosensitizers in PDT. (author)

  10. Porphyrin Diacid-Polyelectrolyte Assemblies: Effective Photocatalysts in Solution

    Directory of Open Access Journals (Sweden)

    Sabine Frühbeißer

    2016-05-01

    Full Text Available Developing effective and versatile photocatalytic systems is of great potential in solar energy conversion. Here we investigate the formation of supramolecular catalysts by electrostatic self-assembly in aqueous solution: Combining positively charged porphyrins with negatively charged polyelectrolytes leads to nanoscale assemblies where, next to electrostatic interactions, π–π interactions also play an important role. Porphyrin diacid-polyelectrolyte assemblies exhibit a substantially enhanced catalytic activity for the light-driven oxidation of iodide. Aggregates with the hexavalent cationic porphyrin diacids show up to 22 times higher catalytic activity than the corresponding aggregates under neutral conditions. The catalytic activity can be increased by increasing the valency of the porphyrin and by choice of the loading ratio. The structural investigation of the supramolecular catalysts took place via atomic force microscopy and small angle neutron scattering. Hence, a new facile concept for the design of efficient and tunable self-assembled photocatalysts is presented.

  11. Thin porphyrin composite membranes with enhanced organic solvent transport

    KAUST Repository

    Phuoc, Duong; Anjum, Dalaver H.; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira

    2018-01-01

    Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block

  12. Challenging Density Functional Theory Calculations with Hemes and Porphyrins

    Science.gov (United States)

    de Visser, Sam P.; Stillman, Martin J.

    2016-01-01

    In this paper we review recent advances in computational chemistry and specifically focus on the chemical description of heme proteins and synthetic porphyrins that act as both mimics of natural processes and technological uses. These are challenging biochemical systems involved in electron transfer as well as biocatalysis processes. In recent years computational tools have improved considerably and now can reproduce experimental spectroscopic and reactivity studies within a reasonable error margin (several kcal·mol−1). This paper gives recent examples from our groups, where we investigated heme and synthetic metal-porphyrin systems. The four case studies highlight how computational modelling can correctly reproduce experimental product distributions, predicted reactivity trends and guide interpretation of electronic structures of complex systems. The case studies focus on the calculations of a variety of spectroscopic features of porphyrins and show how computational modelling gives important insight that explains the experimental spectra and can lead to the design of porphyrins with tuned properties. PMID:27070578

  13. Challenging Density Functional Theory Calculations with Hemes and Porphyrins

    Directory of Open Access Journals (Sweden)

    Sam P. de Visser

    2016-04-01

    Full Text Available In this paper we review recent advances in computational chemistry and specifically focus on the chemical description of heme proteins and synthetic porphyrins that act as both mimics of natural processes and technological uses. These are challenging biochemical systems involved in electron transfer as well as biocatalysis processes. In recent years computational tools have improved considerably and now can reproduce experimental spectroscopic and reactivity studies within a reasonable error margin (several kcal·mol−1. This paper gives recent examples from our groups, where we investigated heme and synthetic metal-porphyrin systems. The four case studies highlight how computational modelling can correctly reproduce experimental product distributions, predicted reactivity trends and guide interpretation of electronic structures of complex systems. The case studies focus on the calculations of a variety of spectroscopic features of porphyrins and show how computational modelling gives important insight that explains the experimental spectra and can lead to the design of porphyrins with tuned properties.

  14. PORPHYRIN METABOLISM AND LIVER FUNCTION IN THE BANTU

    African Journals Online (AJOL)

    method for the detection of urinary coproporphyrin, Mentz5 calculated that ... defect in porphyrin metabolism which is commonly found in the Bantu could be ..... wood,61 traces of uroporphyrin may be excreted in normal urine. As much as 5 ...

  15. Mineralogy of halloysites and their interaction with porphyrine

    Czech Academy of Sciences Publication Activity Database

    Vašutová, V.; Bezdička, Petr; Lang, Kamil; Hradil, David

    2013-01-01

    Roč. 57, č. 3 (2013), s. 243-250 ISSN 0862-5468 Institutional support: RVO:61388980 Keywords : organoclays * mineralogy * porphyrine * CEC Subject RIV: CA - Inorganic Chemistry Impact factor: 0.434, year: 2013

  16. Tetrakis(4-tert-butylphenyl) substituted and fused quinoidal porphyrins

    KAUST Repository

    Zeng, Wangdong

    2012-01-01

    4-tert-Butylphenyl-substituted and fused quinoidal porphyrins 1 and 2 are prepared for the first time. They show (1) intense one-photon absorption in the far-red/near-infrared region, (2) enhanced two-photon absorption compared with aromatic porphyrin monomers, and (3) amphoteric redox behavior. Their geometry and electronic structure are studied by DFT calculations. This journal is © 2012 The Royal Society of Chemistry.

  17. Investigation of the porphyrine role at the mechanism of radioprotection

    International Nuclear Information System (INIS)

    Demoukhamedova, S.D.; Alieva, I.N.; Aliev, D.I.

    2002-01-01

    Full text: To date, it is well known that unfavourable radioecological conditions capable effect on the oxygen transport system in an living organism, particularly, on the conformational state of hemoglobin. Underlying mechanism is more active autoxidation of Hb(O 2 )4 into met-hemoglobin. Decreasing of the oxygen binding to the heme group of protein as a result of modified effect of ionization was observed into peripheral blood of people living on the polluted territory. Porphyrin, the main component of hemoglobin has been showed a wide range radioprotector properties. So, the conformational reorganization of the porphyrin ring plays an important role at the mechanism of hemoglobin functioning. In this report the result of conformational study, quantum-chemical calculations and theoretical calculation of frequencies and intensities of normal oscillations of IR-absorption spectrum of the porphyrin molecule at the NO-binding are presented. Computational program 'LEV' was used in all carried calculations. Due to changes into IR-spectrum of different complexes, the mechanism underlying the ligand bond formation are discussed. The theoretical frequencies of normal oscillations, satisfactorily described the porphyrin experimental IR-spectrum are received. On the base of both obtained normal oscillation forms and potential energy distribution of vibrational coordinates the detailed theoretical interpretation of the porphyrin molecule vibrational spectrum as well as the analysis of the nature of each absorption band the porphyrin molecule IR-spectrum have been carried out. Porphyrin molecule force field analysis has been showed that the ring electron density is irregular. The results of this study may be used at the theoretical calculations of IR-absorption spectrum of different metallo complexes of the porphyrin

  18. Novel non-platinum metal catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel non-platinum metal catalyst material for use in low temperature fuel cells and electrolysers and to fuel cells and electrolysers comprising the novel non-platinum metal catalyst material. The present invention also relates to a novel method for synthesizing...... the novel non-platinum metal catalyst material....

  19. Low platinum catalyst and method of preparation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Di-Jia; Chong, Lina

    2017-11-21

    A low platinum catalyst and method for making same. The catalyst comprises platinum-transition metal bimetallic alloy microcrystallites over a transition metal-nitrogen-carbon composite. A method of making a catalyst comprises preparation of transition metal organic frameworks, infusion of platinum, thermal treatment, and reduction to form the microcrystallites and composite.

  20. Impact of iron porphyrin complexes when hydroprocessing algal HTL biocrude

    Energy Technology Data Exchange (ETDEWEB)

    Jarvis, Jacqueline M.; Sudasinghe, Nilusha M.; Albrecht, Karl O.; Schmidt, Andrew J.; Hallen, Richard T.; Anderson, Daniel B.; Billing, Justin M.; Schaub, Tanner M.

    2016-10-01

    We apply Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for direct characterization of iron-porphyrins in hydrothermal liquefaction (HTL) biocrude oils derived from two algae: Tetraselmis sp. and cyanobacteria. The ironporphyrin compounds are shown to cause catalyst bed plugging during hydroprocessing due to iron deposition. Inductively-coupled plasma optical emission spectrometry (ICPOES) was utilized for iron quantitation in the plugged catalyst beds formed through hydroprocessing of the two HTL biocrudes and identifies an enrichment of iron in the upper five centimeters of the catalyst bed for Tetraselmis sp. (Fe=100,728 ppm) and cyanobacteria (Fe=115,450 ppm). Direct infusion FT-ICR MS analysis of the two HTL biocrudes with optimized instrument conditions facilitates rapid screening and identification of iron-porphyrins without prior chromatographic separation. With FT-ICR MS we identify 138 unique iron-porphyrin compounds in the two HTL biocrudes that are structurally similar to metal-porphyrins (e.g. Ni and V) observed in petroleum. No ironporphyrins are observed in the cyanobacteria HTL biocrude after hydroprocessing, which indicates that iron-porphyrin structures in the HTL biocrude are degraded during hydroprocessing. Hydrodemetallization reactions that occur through hydroprocessing of HTL biocrudes could be responsible for the decomposition of iron-porphyrin structures leading to metal deposition in the catalyst bed that result in catalyst deactivation and bed plugging, and must be addressed for effective upgrading of algal HTL biocrudes.

  1. Randomized phase II trial of carboplatin versus paclitaxel and carboplatin in platinum-sensitive recurrent advanced ovarian carcinoma: a GEICO (Grupo Espanol de Investigacion en Cancer de Ovario) study.

    Science.gov (United States)

    González-Martín, A J; Calvo, E; Bover, I; Rubio, M J; Arcusa, A; Casado, A; Ojeda, B; Balañá, C; Martínez, E; Herrero, A; Pardo, B; Adrover, E; Rifá, J; Godes, M J; Moyano, A; Cervantes, A

    2005-05-01

    The aim of this study was to determine whether the response rate for the paclitaxel-carboplatin combination is superior to carboplatin alone in the treatment of patients with platinum-sensitive recurrent ovarian carcinoma. Patients with recurrent ovarian carcinoma, 6 months after treatment with a platinum-based regimen and with no more than two previous chemotherapy lines, were randomized to receive carboplatin area under the curve (AUC) 5 (arm A) or paclitaxel 175 mg/m(2) + carboplatin AUC 5 (arm B). The primary end point was objective response, following a 'pick up the winner' design. Secondary end points included time to progression (TTP), overall survival, tolerability and quality of life (QoL). Eighty-one patients were randomized and included in the intention-to-treat analysis. The response rate in arm B was 75.6% [26.8% complete response (CR) + 48.8% partial response (PR)] [95% confidence interval (CI) 59.7% to 87.6%] and 50% in arm A (20% CR + 30% PR) (95% CI 33.8% to 66.2%). No significant differences were observed in grade 3-4 hematological toxicity. Conversely, mucositis, myalgia/arthralgia and peripheral neurophaty were more frequent in arm B. Median TTP was 49.1 weeks in arm B (95% CI 36.9-61.3) and 33.7 weeks in arm A (95% CI 25.8-41.5). No significant differences were found in the QoL analysis. Paclitaxel-carboplatin combination is a tolerable regimen with a higher response rate than carboplatin monotherapy in platinum-sensitive recurrent ovarian carcinoma.

  2. Porphyrin Co(III-Nitrene Radical Mediated Pathway for Synthesis of o-Aminoazobenzenes

    Directory of Open Access Journals (Sweden)

    Monalisa Goswami

    2018-05-01

    Full Text Available Azobenzenes are versatile compounds with a range of applications, including dyes and pigments, food additives, indicators, radical reaction initiators, molecular switches, etc. In this context, we report a general method for synthesizing o-aminoazobenzenes using the commercially available cobalt(II tetraphenyl porphyrin [CoII(TPP]. The net reaction is a formal dimerization of two phenyl azides with concomitant loss of two molecules of dinitrogen. The most commonly used methodology to synthesize azobenzenes is based on the initial diazotization of an aromatic primary amine at low temperatures, which then reacts with an electron rich aromatic nucleophile. As such, this limits the synthesis of azobenzenes with an amine functionality. In contrast, the method we report here relies heavily on the o-amine moiety and retains it in the product. The reaction is metal catalyzed and proceeds through a porphyrin Co(III-nitrene radical intermediate, which is known to form on activation of organic azides at the cobalt center. The synthesized o-aminoazobenzenes are bathochromatically shifted, as compared to azobenzenes without amine substituents. Based on the crystal structure of one of the products, strong H-bonding between the N-atom of the azo functionality and the H of the NH2 substituent is shown to stabilize the trans isomeric form of the product. The NH2 substituents offers possibilities for further functionalization of the synthesized azo compounds.

  3. Influence of substituents in meso-aryl groups of iron l-oxo porphyrins\

    Czech Academy of Sciences Publication Activity Database

    Tabor, Edyta; Poltowicz, J.; Pamin, K.; Basag, S.; Kubiak, W.

    2016-01-01

    Roč. 119, NOV 2016 (2016), s. 342-349 ISSN 0277-5387 Institutional support: RVO:61388955 Keywords : iron porphyrins * μ-Oxo porphyrins * oxidation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.926, year: 2016

  4. Supramolecular assemblies of pyridyl porphyrin and diazadithia phthalocyanine

    Directory of Open Access Journals (Sweden)

    OZER BEKAROGLU

    1999-08-01

    Full Text Available In this paper we report for the first time on a mixed complex between the cationic porphyrin 5, 10, 15, 20-tetra-N- -methyl-pyrydinium-p-il porphyrin (TMPyP and a new metal phthalocyanine with four 16-membered diazadithia macrocycles (denoted here as Pc16, in order to obtain an active complex with an intense absorption on the lower energy side of the visible spectrum and with a higher sensitivity in photodynamic therapy of cancer. The dimerization constant for Pc16 and also the ratio between the oscillator strengths for monomeric and dimeric forms of this compound, were evaluated. The ratio between these oscillator strengths was 2.01 showing a certain dimerization process. The Job mathematical method allowed the establishment of the stoichiometry and the formation constants for the heteroaggregates between the porphyrin and the phthalocy- anine (a diad between one phthalocyanine molecule and one porphyrin molecule and a triad between two phthalocyanine molecules and only one porphyrin molecule. The coulombic attraction resulting from the p-p interaction of the two highly conjugated macrocycles and from the interaction between the substituents, favors a face-to-face geometry.

  5. Real-time observation of ultrafast electron injection at graphene–Zn porphyrin interfaces

    KAUST Repository

    Masih, Dilshad

    2015-02-25

    We report on the ultrafast interfacial electron transfer ( ET) between zinc( II) porphyrin ( ZnTMPyP) and negatively charged graphene carboxylate ( GC) using state- of- the- art femtosecond laser spectroscopy with broadband capabilities. The steady- state interaction between GC and ZnTMPyP results in a red- shifted absorption spectrum, providing a clear indication for the binding affinity between ZnTMPyP and GC via electrostatic and p- p stacking interactions. Ultrafast transient absorption ( TA) spectra in the absence and presence of three different GC concentrations reveal ( i) the ultrafast formation of singlet excited ZnTMPyP*, which partially relaxes into a long- lived triplet state, and ( ii) ET from the singlet excited ZnTMPyP* to GC, forming ZnTMPyP + and GC , as indicated by a spectral feature at 650- 750 nm, which is attributed to a ZnTMPyP radical cation resulting from the ET process.

  6. A Porphyrin Based Potentiometric Sensor for Zn2+ Determination

    Directory of Open Access Journals (Sweden)

    H. Lang

    2003-07-01

    Full Text Available PVC based membranes of disodium salt of porphyrin 3,7,12,17-tetramethyl-8, 13-divinyl 2,18-porphine dipropionic acid (I as ionophore with sodium tetra phenyl borate (NaTPB as anion excluder and dibutyl phthalate (DBP, dioctyl phthalate (DOP, dibutyl butyl phosphonate (DBBP, tris(2- ethyl hexylphosphate (TEP, tri-n-butylphosphate (TBP and 1- chloronaphthalene (CN as plasticizing solvent mediators were prepared and constructed for determination of Zn(II. The PVC based membrane of (I with DBBP as plasticizer and having anion excluder, NaTPB in the ratio PVC: I: NaTPB: DBBP (150: 10: 2: 200 gave the best results in terms of working concentration range (1.3×10-5-1.0 ×10-1M with a Nernstian slope (30.0 mV/decade of activity. The useful pH range of the sensor is 3.0 –7.4, beyond which a drift in potential was observed. The response time of the sensor is 10s and the lifetime was about 2 months during which it could be used without any measurable divergence. It had good stability and reproducibility. The membrane worked satisfactorily in non-aqueous medium up to 40% (v/v non-aqueous content. The selectivity coefficient values indicate that the electrode is highly selective for Zn2+ over a number of other cations except Na+ and Cd2+. Although Na+ and Cd2+ are likely to cause some interference, they would not interfere if present at the concentrations < 1 ×10-5 and < 5 ×10-5 M, respectively. The electrode has been used as an indicator electrode to determine the end point in the potentiometric titration of Zn2+ with EDTA.

  7. Ruthenium porphyrin-induced photodamage in bladder cancer cells.

    Science.gov (United States)

    Bogoeva, Vanya; Siksjø, Monica; Sæterbø, Kristin G; Melø, Thor Bernt; Bjørkøy, Astrid; Lindgren, Mikael; Gederaas, Odrun A

    2016-06-01

    Photodynamic therapy (PDT) is a noninvasive treatment for solid malignant and flat tumors. Light activated sensitizers catalyze photochemical reactions that produce reactive oxygen species which can cause cancer cell death. In this work we investigated the photophysical properties of the photosensitizer ruthenium(II) porphyrin (RuP), along with its PDT efficiency onto rat bladder cancer cells (AY27). Optical spectroscopy verified that RuP is capable to activate singlet oxygen via blue and red absorption bands and inter system crossing (ISC) to the triplet state. In vitro experiments on AY27 indicated increased photo-toxicity of RuP (20μM, 18h incubation) after cell illumination (at 435nm), as a function of blue light exposure. Cell survival fraction was significantly reduced to 14% after illumination of 20μM RuP with 15.6J/cm(2), whereas the "dark toxicity" of 20μM RuP was 17%. Structural and morphological changes of cells were observed, due to RuP accumulation, as well as light-dependent cell death was recorded by confocal microscopy. Flow cytometry verified that PDT-RuP (50μM) triggered significant photo-induced cellular destruction with a photoxicity of (93%±0.9%). Interestingly, the present investigation of RuP-PDT showed that the dominating mode of cell death is necrosis. RuP "dark toxicity" compared to the conventional chemotherapeutic drug cisplatin was higher, both evaluated by the MTT assay (24h). In conclusion, the present investigation shows that RuP with or without photoactivation induces cell death of bladder cancer cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Multi-step intramolecular excitation energy transfer in dendritic pyrene-phosphorus(V)porphyrin heptads

    International Nuclear Information System (INIS)

    Hirakawa, Kazutaka; Segawa, Hiroshi

    2016-01-01

    Dendritic heptad molecules in which four pyrenyl groups are connected at the central phosphorus atom of the edge-porphyrins of the center-to-edge type porphyrin trimers were synthesized to investigate a multi-step excitation energy transfer. As the central energy acceptor, two types porphyrins which one was phosphorus(V)tetraphenylporphyrin (H2) and another was its derivative substituted by butoxy groups at four para-position of meso-phenyl groups (H1) were used. In the photoexcited state of the pyrene units, the excitation energy transfer to the central-porphyrin unit was observed in toluene. The excitation energy transfer is considered to be through two pathways; one is a stepwise pathway through the edge-porphyrin unit and another is a direct excitation energy transfer to the central porphyrin. The direct excitation energy transfer from pyrenes to the edge-porphyrin and central-porphyrin were observed in the case for H1. From the excited state of the edge-porphyrins, the excitation energy transfer to the central-porphyrin occurs in the H1 case. In the H2 case, the excitation energy of central-porphyrin is higher than that of H1, and the electron transfer from edge-porphyrin to the central-porphyrin become predominant process. - Highlights: • Dendritic pyrene-porphyrin heptads were synthesized. • Excitation energy transfer occurs from the pyrenyl moiety to the phosphorus(V)porphyrin. • The stepwise and direct energy transfer pathways were observed. • The quantum yields of these energy transfer pathways could be determined.

  9. Multi-step intramolecular excitation energy transfer in dendritic pyrene-phosphorus(V)porphyrin heptads

    Energy Technology Data Exchange (ETDEWEB)

    Hirakawa, Kazutaka, E-mail: hirakawa.kazutaka@shizuoka.ac.jp [Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Department of Optoelectronics and Nanostructure Science, Graduate School of Science and Technology, Shizuoka University, Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Segawa, Hiroshi [Department of Multi-Disciplinary Science - General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8904 (Japan); Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo 153-8904 (Japan)

    2016-11-15

    Dendritic heptad molecules in which four pyrenyl groups are connected at the central phosphorus atom of the edge-porphyrins of the center-to-edge type porphyrin trimers were synthesized to investigate a multi-step excitation energy transfer. As the central energy acceptor, two types porphyrins which one was phosphorus(V)tetraphenylporphyrin (H2) and another was its derivative substituted by butoxy groups at four para-position of meso-phenyl groups (H1) were used. In the photoexcited state of the pyrene units, the excitation energy transfer to the central-porphyrin unit was observed in toluene. The excitation energy transfer is considered to be through two pathways; one is a stepwise pathway through the edge-porphyrin unit and another is a direct excitation energy transfer to the central porphyrin. The direct excitation energy transfer from pyrenes to the edge-porphyrin and central-porphyrin were observed in the case for H1. From the excited state of the edge-porphyrins, the excitation energy transfer to the central-porphyrin occurs in the H1 case. In the H2 case, the excitation energy of central-porphyrin is higher than that of H1, and the electron transfer from edge-porphyrin to the central-porphyrin become predominant process. - Highlights: • Dendritic pyrene-porphyrin heptads were synthesized. • Excitation energy transfer occurs from the pyrenyl moiety to the phosphorus(V)porphyrin. • The stepwise and direct energy transfer pathways were observed. • The quantum yields of these energy transfer pathways could be determined.

  10. Electroreduction of CO2 Catalyzed by a Heterogenized Zn–Porphyrin Complex with a Redox-Innocent Metal Center

    Science.gov (United States)

    2017-01-01

    Transition-metal-based molecular complexes are a class of catalyst materials for electrochemical CO2 reduction to CO that can be rationally designed to deliver high catalytic performance. One common mechanistic feature of these electrocatalysts developed thus far is an electrogenerated reduced metal center associated with catalytic CO2 reduction. Here we report a heterogenized zinc–porphyrin complex (zinc(II) 5,10,15,20-tetramesitylporphyrin) as an electrocatalyst that delivers a turnover frequency as high as 14.4 site–1 s–1 and a Faradaic efficiency as high as 95% for CO2 electroreduction to CO at −1.7 V vs the standard hydrogen electrode in an organic/water mixed electrolyte. While the Zn center is critical to the observed catalysis, in situ and operando X-ray absorption spectroscopic studies reveal that it is redox-innocent throughout the potential range. Cyclic voltammetry indicates that the porphyrin ligand may act as a redox mediator. Chemical reduction of the zinc–porphyrin complex further confirms that the reduction is ligand-based and the reduced species can react with CO2. This represents the first example of a transition-metal complex for CO2 electroreduction catalysis with its metal center being redox-innocent under working conditions. PMID:28852698

  11. Fixed distance photoinduced electron transfer between Fe and Zn porphyrins encapsulated within the Zn HKUST-1 metal organic framework.

    Science.gov (United States)

    Larsen, Randy W; Wojtas, Lukasz

    2015-02-21

    An attractive strategy for the development of photocatalytic metal organic framework (MOF) materials is to co-encapsulate a photoactive electron donor with a catalytic electron acceptor within the MOF. Here we report the co-encapsulation of both Zn(ii) tetrakis(tetra 4-sulphonatophenyl)porphyrin (Zn4SP) and Fe(iii) tetrakis(tetra 4-sulphonatophenyl)porphyrin (Fe4SP) into an HKUST-1 (Zn) MOF and demonstrate photoinduced electron transfer (ET) between the co-encapsulated guest. Photo-excitation of the Zn4SP results in fixed-distance inter-molecular ET between the encapsulated (3)Zn4SP and the Fe(iii)4SP as evident by the reduction in the encapsulated (3)Zn4SP lifetime from 890 μs (kobs = 1.1 × 10(3) s(-1)) to 83 μs (kobs = 1.2 × 10(4) s(-1)) in the presence of Fe4SP giving a kET ∼ 1.1 × 10(4) s(-1). The data are consistent with ET taking place between encapsulated porphyrins that are two cages apart in distance with a reorganizational energy of ∼1.65 eV, β = 1.25 and ΔG° = -0.97 eV (within a semi-classical Marcus theory framework).

  12. Structural property of platinum mononitride

    International Nuclear Information System (INIS)

    Yu, L.H.; Yao, K.L.; Liu, Z.L.; Zhang, Y.S.

    2007-01-01

    The structural stability and pressure-induced structural phase transition of platinum mononitride (PtN), as well as its electronic structure, were studied using the full potential augmented plane wave plus local orbitals method with the generalized gradient approximation (GGA) exchange-correlation functional. The total energy calculations show that the optimized wurtzite structure is most stable energetically among four structures: zinc blende, rocksalt, CsCl and wurtzite, which reveals the platinum mononitride PtN perhaps crystallizes in the wurtzite structure; the pressure of phase transition from wurtzite to rocksalt is predicted to be 41.4 GPa.The calculated bulk modulus of the wurtzite structure is 99.41 GPa, which is smaller than that of the other three structures and face-centered cubic Pt. The band structure calculations show wurtzite PtN is metallic

  13. Rhenium–platinum antitumor systems

    Directory of Open Access Journals (Sweden)

    A. V. Shtemenko

    2017-04-01

    Full Text Available This review provides an overlook of design (in short, antitumor and other biological activity of quadruple-bonded cluster dirhenium(III compounds and their synergism with cisplatin. In particular, we describe the work of the rhenium-platinum antitumor system (introduction of rhenium and platinum compounds. Among known metal-based anticancer drugs and drug candidates dirhenium(III compounds differ profoundly due to their strong antiradical and antioxidant properties determined by quadruple bond unsaturation. Such advantages of metal complexes as more expressed redox chemical propertie should be exploited for creating more efficient anticancer drugs. Combination of drugs leads to synergistic effects and/or to lowe­ring toxicity of platinides and is very promising in cancer chemotherapy. The review covers the follo­wing items: design of quadruple bonded dirhenium(III clusters, their spectral and antiradical properties (in short; interaction of the dirhenium(III compounds with lipids and formation of liposomes; interaction of the dirhenium(III compounds with erythrocytes and their antihemolytic activity in the models of hemolytic anemia; anticancer activity of dirhenium clusters and work of the rhenium-platinum antitumor system; antianemic and antioxidant properties of the dirhenium(III compounds in the model of tumor growth; interaction of the dirhenium(III compounds with nucleobases and DNA. Some modern trends in the field of bioinorganic and medicinal chemi­stry are also considered regarding their connection to the rhenium-platinum system efficiency: use of combinational therapy and nanomaterials; involvement of some biologically active ligands and redox-activation strategy, etc.

  14. MINERALOGY OF HALLOYSITES AND THEIR INTERACTION WITH PORPHYRINE

    Directory of Open Access Journals (Sweden)

    Vašutová V.

    2013-09-01

    Full Text Available Samples representing two modifications of halloysites, dehydrated (7 Å and hydrated (10 Å forms, respectively, were examined with the aim to select suitable candidates for to be used as carriers of porphyrine photoactive molecules. The samples were analysed by powder X-ray diffraction (pXRD, infrared spectroscopy (FT-IR, and high resolution transmission electron microscopy (HRTEM. Chemical composition was also determined. For the determination of cationic exchange capacity (CEC the silver thiourea method (AgTU was used. Silver cations concentrations in the solution before and after the interaction were determined by atomic absorption spectrometry (AAS. By the interaction of two pure hydrated halloysites with porphyrine it was found that porphyrine does not intercalate the interlayer space, but it is adsorbed on the outer surface of halloysite. This interaction changed the colour of clay sample from white to green. The changes were also clearly visible on diffuse reflectance spectra (DRS.

  15. Interaction of porphyrins with CdTe quantum dots

    International Nuclear Information System (INIS)

    Zhang Xing; Liu Zhongxin; Ma Lun; Hossu, Marius; Chen Wei

    2011-01-01

    Porphyrins may be used as photosensitizers for photodynamic therapy, photocatalysts for organic pollutant dissociation, agents for medical imaging and diagnostics, applications in luminescence and electronics. The detection of porphyrins is significantly important and here the interaction of protoporphyrin-IX (PPIX) with CdTe quantum dots was studied. It was observed that the luminescence of CdTe quantum dots was quenched dramatically in the presence of PPIX. When CdTe quantum dots were embedded into silica layers, almost no quenching by PPIX was observed. This indicates that PPIX may interact and alter CdTe quantum dots and thus quench their luminescence. The oxidation of the stabilizers such as thioglycolic acid (TGA) as well as the nanoparticles by the singlet oxygen generated from PPIX is most likely responsible for the luminescence quenching. The quenching of quantum dot luminescence by porphyrins may provide a new method for photosensitizer detection.

  16. Role of complement in porphyrin-induced photosensitivity

    International Nuclear Information System (INIS)

    Lim, H.W.; Gigli, I.

    1981-01-01

    Addition of porphyrins to sera of guinea pigs in vitro, followed by irradiation with 405 nm light, resulted in dose-dependent inhibitions of hemolytic activity of complement. With guinea pig as an animal model, we also found that systemically administered porphyrins, followed by irradiation with 405 nm light, resulted in dose-dependent inhibition of CH50 in vivo. The erythrocytes from porphyrin-treated guinea pigs showed an increased susceptibility to hemolysis induced by 405 nm irradiation in vitro. Clinical changes in these animals were limited to light-exposed areas and consisted of erythema, crusting, and delayed growth of hair. Histologically, dermal edema, dilation of blood vessels, and infiltration of mononuclear and polymorphonuclear cells were observed. Guinea pigs irradiated with ultraviolet-B developed erythema, but had no alteration of their complement profiles. It is suggested that complement products may play a specific role in the pathogenesis of the cutaneous lesions of some porphyrias

  17. Radiation and platinum drug interaction

    International Nuclear Information System (INIS)

    Nias, A.H.W.

    1985-01-01

    The ideal platinum drug-radiation interaction would achieve radiosensitization of hypoxic tumour cells with the use of a dose of drug which is completely non-toxic to normal tissues. Electron-affinic agents are employed with this aim, but the commoner platinum drugs are only weakly electron-affinic. They do have a quasi-alkylating action however, and this DNA targeting may account for the radiosensitizing effect which occurs with both pre- and post-radiation treatments. Because toxic drug dosage is usually required for this, the evidence of the biological responses to the drug and to the radiation, as well as to the combination, requires critical analysis before any claim of true enhancement, rather than simple additivity, can be accepted. The amount of enhancement will vary with both the platinum drug dose and the time interval between drug administration and radiation. Clinical schedules may produce an increase in tumour response and/or morbidity, depending upon such dose and time relationships. (author)

  18. Theoretical study on junctions in porphyrin oligomers for nano scale devices

    International Nuclear Information System (INIS)

    Mizuseki, Hiroshi; Belosludov, Rodion V.; Farajian, Amir A.; Igarashi, Nobuaki; Kawazoe, Yoshiyuki

    2005-01-01

    A unimolecular rectifier could be built by combining two molecular sub-units that contain acceptor or donor groups. Porphyrin possesses good electron-donating properties due to its large, easily ionized, π-conjugated system. In this study, we propose that a rectifier diode could be created by combining two metal porphyrin molecules containing different metal atoms. This function would realize an effect similar to a p-n junction in a solid-state device. A Zn porphyrin-Ni porphyrin junction in a non-conjugated porphyrin system displays a localization of frontier orbitals that is similar to a rectifier function

  19. DNA-binding studies of a tetraalkyl-substituted porphyrin and the mutually adaptive distortion principle.

    Science.gov (United States)

    Ghimire, Srijana; Fanwick, Phillip E; McMillin, David R

    2014-10-20

    This investigation explores DNA-binding interactions of various forms of an alkyl-substituted cationic porphyrin, H2TC3 (5,10,15,20-tetra[3-(3'-methylimidazolium-1'-yl)]porphyrin). The motivating idea is that incorporating alkyl rather than aryl substituents in the meso positions will enhance the prospects for intercalative as well as external binding to DNA hosts. The ligands may also be applicable for photodynamic and/or anticancer therapy. Methods employed include absorbance, circular dichroism, and emission spectroscopies, as well as viscometry and X-ray crystallography. By comparison with the classical H2T4 system, H2TC3 exhibits a higher molar extinction coefficient but is more prone to self-association. Findings of note include that the copper(II)-containing form Cu(TC3) is adept at internalizing into single-stranded as well as B-form DNA, regardless of the base composition. Surprisingly, however, external binding of H2TC3 occurs within domains that are rich in adenine-thymine base pairs. The difference in the deformability of H2TC3 versus Cu(TC3) probably accounts for the reactivity difference. Finally, Zn(TC3) binds externally, as the metal center remains five-coordinate.

  20. An unsymmetrical porphyrin and its metal complexes: synthesis, spectroscopy, thermal analysis and liquid crystal properties

    Directory of Open Access Journals (Sweden)

    CHANGFU ZHUANG

    2009-09-01

    Full Text Available The synthesis and characterization of a new unsymmetrical porphyrin liquid crystal, 5-(4-stearoyloxyphenylphenyl-10,15,20-triphenylporphyrin (SPTPPH2 and its transition metal complexes (SPTPPM, M(II = Zn, Fe, Co, Ni, Cu or Mn are reported. Their structure and properties were studied by elemental analysis, and UV–Vis, IR, mass and 1H-HMR spectroscopy. Their luminescent properties were studied by excitation and emission spectroscopy. The quantum yields of the S1 ® S0 fluorescence were measured at room temperature. According to thermal studies, the complexes have a higher thermal stability (no decomposition until 200 °C. Differential scanning calorimetry (DSC data and an optical textural photograph, obtained using a polarizing microscope (POM, indicate that the porphyrin ligand had liquid crystalline character and that it exhibited more than one mesophase and a low-lying phase transition temperature, with transition temperatures of 19.3 and 79.4 °C; the temperature range of the liquid crystal (LC phase of the ligand was 70.1 °C.

  1. Phosphoric acid fuel cell platinum use study

    Science.gov (United States)

    Lundblad, H. L.

    1983-05-01

    The U.S. Department of Energy is promoting the private development of phosphoric acid fuel cell (PAFC) power plants for terrestrial applications. Current PAFC technology utilizes platinum as catalysts in the power electrodes. The possible repercussions that the platinum demand of PAFC power plant commercialization will have on the worldwide supply and price of platinum from the outset of commercialization to the year 2000 are investigated. The platinum demand of PAFC commercialization is estimated by developing forecasts of platinum use per unit of generating capacity and penetration of PAFC power plants into the electric generation market. The ability of the platinum supply market to meet future demands is gauged by assessing the size of platinum reserves and the capability of platinum producers to extract, refine and market sufficient quantities of these reserves. The size and timing of platinum price shifts induced by the added demand of PAFC commercialization are investigated by several analytical methods. Estimates of these price shifts are then used to calculate the subsequent effects on PAFC power plant capital costs.

  2. Effects of Immersion Solvent on Photovoltaic and Photophysical Properties of Porphyrin-Sensitized Solar Cells.

    Science.gov (United States)

    Hayashi, Hironobu; Higashino, Tomohiro; Kinjo, Yuriko; Fujimori, Yamato; Kurotobi, Kei; Chabera, Pavel; Sundström, Villy; Isoda, Seiji; Imahori, Hiroshi

    2015-08-26

    Memory effects in self-assembled monolayers (SAMs) of zinc porphyrin carboxylic acid on TiO2 electrodes have been demonstrated for the first time by evaluating the photovoltaic and electron transfer properties of porphyrin-sensitized solar cells prepared by using different immersion solvents sequentially. The structure of the SAM of the porphyrin on the TiO2 was maintained even after treating the porphyrin monolayer with different neat immersion solvents (memory effect), whereas it was altered by treatment with solutions containing different porphyrins (inverse memory effect). Infrared spectroscopy shows that the porphyrins in the SAM on the TiO2 could be exchanged with the same or analogous porphyrin, leading to a change in the structure of the porphyrin SAM. The memory and inverse memory effects are well correlated with a change in porphyrin geometry, mainly the tilt angle of the porphyrin along the long molecular axis from the surface normal on the TiO2, as well as with kinetics of electron transfer between the porphyrin and TiO2. Such a new structure-function relationship for DSSCs will be very useful for the rational design and optimization of photoelectrochemical and photovoltaic properties of molecular assemblies on semiconductor surfaces.

  3. Three novel metal-organic frameworks based on flexible porphyrin tetracarboxylic acids as highly effective catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zengqi [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi’an, Shaanxi 710069 (China); Su, Xiaoqin [School of Materials and Chemical Engineering, Xi’an Technological University, Xi’an, Shaanxi 710021 (China); Yu, Fan; Li, Jun [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi’an, Shaanxi 710069 (China)

    2016-06-15

    Targeted synthesis of metalloporphyrinic frameworks (MPFs) with Cu(II) (1), Ni(II) (2, 3) 5, 10, 15, 20-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin (Cu(TCMOPP) and Ni(TCMOPP)) as building blocks afforded three new extended coordination polymers inter-linked by Zn(II) (1) and K(I) (2, 3). 1 shows 2D frameworks while 2, 3 are 3D frameworks. The open channel are 7–17 Å wide and accessible to guest/solvent molecules. Besides, the thermogravimetric analyses (TGA) indicate that the framework structures of the three compounds are stable until 300 °C. In addition, the catalytic activities of 1–3 to the alkylbenzenes oxidation are examined, and the results indicate that 1 exhibit high catalytic activity to oxidation of ethylbenzene and 1,2,3,4-tetrahydronaphthalene with conversion of 64.1% and 80.3% respectively. - Graphical abstract: Three novel metalloporphyrinic frameworks (1, 2, 3) were synthesized based on tetracarboxylic Cu(II) (1), Ni(II) (2, 3) metalloporphyrin inter-linked by Zn(II) (1) , K(I) (2, 3), and 1 shows high catalytic activity to oxidation reaction of alkylbenzenes with conversion 80.3%. Display Omitted.

  4. Prediction of ligand effects in platinum-amyloid-β coordination.

    Science.gov (United States)

    Turner, Matthew; Deeth, Robert J; Platts, James A

    2017-08-01

    Ligand field molecular mechanics (LFMM) and semi-empirical Parametric Model 7 (PM7) methods are applied to a series of six Pt II -Ligand systems binding to the N-terminal domain of the amyloid-β (Aβ) peptide. Molecular dynamics using a combined LFMM/Assisted Model Building with Energy Refinement (AMBER) approach is used to explore the conformational freedom of the peptide fragment, and identifies favourable platinum binding modes and peptide conformations for each ligand investigated. Platinum coordination is found to depend on the nature of the ligand, providing evidence that binding mode may be controlled by suitable ligand design. Boltzmann populations at 310K indicate that each Pt-Aβ complex has a small number of thermodynamically accessible states. Ramachandran maps are constructed for the sampled Pt-Aβ conformations and secondary structural analysis of the obtained complex structures is performed and contrasted with the free peptide; coordination of these platinum complexes disrupts existing secondary structure in the Aβ peptide and promotes formation of ligand-specific turn-type secondary structure. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Room temperature synthesis of colloidal platinum nanoparticles

    Indian Academy of Sciences (India)

    Unknown

    platinum cation used. ... Particle size increased with low reagent concentration. ... 2,100) was added separately to the starting solution. Argon gas was bubbled in the solution for 20 min. Later, reduction of platinum ions was carried out by bubbling hydrogen gas ... plex to aquate (Cl– → H2O ligand exchange). ... copper grid.

  6. A Change to the Platinum Publications | Poster

    Science.gov (United States)

    Please be advised that the Poster will no longer publish the “Platinum Publications” series listing recent NCI at Frederick publications. All published research represents a valuable addition to the fight against cancer, AIDS, and infectious diseases—thus, the “Platinum Publications” did not adequately commend all of the important work done by NCI at Frederick researchers.

  7. Collective Behavior of Water on Platinum

    Science.gov (United States)

    Limmer, David; Willard, Adam; Chandler, David

    2012-02-01

    We present the results of molecular dynamics simulations of a interface between water and a platinum electrode. Using importance sampling techniques we probe a variety of collective phenomenon that emerge at the interface. We consider platinum electrodes with two different geometries and discuss how different behaviors result from a competition between geometrical frustration and favorable local interactions.

  8. Re(I) bridged porphyrin dyads, triads and tetrads

    Indian Academy of Sciences (India)

    DNA cleavage.4 Design strategies to develop solid-state multichromophore arrays of defined rigidity, ... lent synthetic strategies to porphyrin arrays have gen- erally proved quite limiting. The covalent synthetic ...... since retention times vary inversely with size.23 Pulsed- field-gradient NMR, which measures coefficients for.

  9. Expanded porphyrins as third order non-linear optical materials ...

    Indian Academy of Sciences (India)

    WINTEC

    function correlations ... An understanding of the structure–function corre- lations of these expanded porphyrins is an important first step for ... where χ (2) and χ (3) are the quadratic χ (2) (first- order) and χ (3) cubic (second-order) susceptibilities.

  10. Interaction of porphyrins with PAMAM dendrimers in aqueous solution

    Czech Academy of Sciences Publication Activity Database

    Kubát, Pavel; Lang, Kamil; Zelinger, Zdeněk

    2007-01-01

    Roč. 131, - (2007), s. 200-205 ISSN 0167-7322 R&D Projects: GA ČR GA203/04/0426 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : porphyrin * PAMAM dendrimer * aggragation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.982, year: 2007

  11. Synthesis of metallic nanoshells on porphyrin-stabilized emulsions

    Science.gov (United States)

    Wang, Haorong [Albuquerque, NM; Song, Yujiang [Albuquerque, NM; Shelnutt, John A [Tijeras, NM; Medforth, Craig J [Winters, CA

    2011-12-13

    Metal nanostructures formed by photocatalytic interfacial synthesis using a porphyrin-stabilized emulsion template and the method for making the nanostructures. Catalyst-seeded emulsion droplets are employed as templates for hollow-nanoshell growth. The hollow metal nanospheres may be formed with or without inclusions of other materials.

  12. Trilobolide-porphyrin conjugates: On synthesis and biological effects evaluation

    Czech Academy of Sciences Publication Activity Database

    Tomanová, P.; Rimpelová, S.; Jurášek, M.; Buděšínský, Miloš; Vejvodová, L.; Ruml, T.; Kmoníčková, E.; Drašar, P. B.

    2015-01-01

    Roč. 97, SI (2015), s. 8-12 ISSN 0039-128X Grant - others:GA ČR(CZ) GA14-04329S; GA MŠk(CZ) ED2.1.00/03.0076 Institutional support: RVO:61388963 Keywords : trilobolide * porphyrin * nitric oxide * fluorescence microscopy Subject RIV: CE - Biochemistry Impact factor: 2.513, year: 2015

  13. Porphyrin involvement in redshift fluorescence in dentin decay

    Science.gov (United States)

    Slimani, A.; Panayotov, I.; Levallois, B.; Cloitre, T.; Gergely, C.; Bec, N.; Larroque, C.; Tassery, H.; Cuisinier, F.

    2014-05-01

    The aim of this study was to evaluate the porphyrin involvement in the red fluorescence observed in dental caries with Soprolife® light-induced fluorescence camera in treatments mode (SOPRO, ACTEON Group, La Ciotat, France) and Vistacam® camera (DÜRR DENTAL AG, Bietigheim-Bissingen, Germany). The International Caries Detection and Assessment System (ICDAS) was used to rand the samples. Human teeth cross-sections, ranked from ICDAS score 0 to 6, were examined by epi-fluorescence microscopy and Confocal Raman microscopy. Comparable studies were done with Protoporphyrin IX, Porphyrin I and Pentosidine solutions. An RGB analysis of Soprolife® images was performed using ImageJ Software (1.46r, National Institutes of Health, USA). Fluorescence spectroscopy and MicroRaman spectroscopy revealed the presence of Protoporphyrin IX, in carious enamel, dentin and dental plaque. However, the presence of porphyrin I and pentosidine cannot be excluded. The results indicated that not only porphyrin were implicated in the red fluorescence, Advanced Glygation Endproducts (AGEs) of the Maillard reaction also contributed to this phenomenon.

  14. Platinum-group element mineralization

    International Nuclear Information System (INIS)

    Gruenewaldt, G.

    1985-01-01

    The purpose of this investigation is to determine the geological processes responsible for the abnormal enrichment of the platinum-group elements (PGE) in the mineralized layers of the Bushveld Complex. Questions asked are: what processes caused enrichment of the Bushveld magma in the PGE ; by what processes were these PGE concentrated in the mineralized layers ; was contamination of the Bushveld magma from external sources important in the formation of the PGE enriched layers ; what are the effects of fractional crystallization on the PGE ratios

  15. P-glycoprotein expression and DNA topoisomerase I and II activity in benign tumors of the ovary and in malignant tumors of the ovary, before and after platinum/cyclophosphamide chemotherapy

    NARCIS (Netherlands)

    van der Zee, A G; Hollema, H; de Jong, S; Boonstra, H; Gouw, A; Willemse, P H; Zijlstra, J G; de Vries, E G; de Jong, Steven

    1991-01-01

    P-glycoprotein (P-gp) expression and DNA topoisomerase (Topo) II are important variables in multidrug resistant tumor cell lines. The aim of this study was to evaluate P-gp expression and Topo I and II activity in benign and malignant epithelial ovarian tumors. P-gp expression was analyzed

  16. Tin dioxide sol-gel derived films doped with platinum and antimony deposited on porous silicon

    NARCIS (Netherlands)

    Savaniu, C.; Arnautu, A.; Cobianu, C.; Craciun, G.; Flueraru, C.; Zaharescu, M.; Parlog, C.; Paszti, F.; van den Berg, Albert

    1999-01-01

    SnO2 sol-gel derived thin films doped simultaneously with Pt and Sb are obtained and reported for the first time. The Sn sources were tin(IV) ethoxide or tin(II) ethylhexanoate, while hexachloroplatinic acid (H2PtCl6) and antimony chloride (SbCl3) were used as platinum and antimony sources,

  17. Bionic catalysis of porphyrin for electrochemical detection of nucleic acids

    International Nuclear Information System (INIS)

    Li Jie; Lei Jianping; Wang Quanbo; Wang Peng; Ju Huangxian

    2012-01-01

    Highlights: ► This is the first application of bionic catalysis of porphyrin as detection probe in bioanalysis. ► Porphyrin–DNA–gold nanoparticle probe is synthesized. ► Binding model between FeTMPyP and DNA is verified. ► The detection probe shows excellent electrocatalytic behaviors toward the reduction of O 2 . ► The biosensor exhibited good performance with wide linear range and high specificity. - Abstract: A novel electrochemical strategy was designed for the detection of DNA based on the bionic catalysis of porphyrin. The detection probe was prepared via the assembly of thiolated double strand DNA (dsDNA) with gold nanoparticles (AuNPs), and then interacted with cationic iron (III) meso-tetrakis (N-methylphyridinum-4-yl) porphyrin (FeTMPyP) via groove binding along the dsDNA surface. The resulting nanocomplex was characterized with transmission electron microscopy, UV–vis absorption and circular dichroism spectroscopy. The FeTMPyP–DNA–AuNPs probe on gold electrode demonstrated the excellent electrocatalytic behaviors toward the reduction of O 2 due to the largely loading of FeTMPyP and good conductivity. Based on bionic catalysis of porphyrin for the reduction of O 2 , the resulting biosensor exhibited a good performance for the detection of DNA with a wide linear range from 1 × 10 −12 to 1 × 10 −8 mol L −1 and detection limit of 2.5 × 10 −13 mol L −1 at the signal/noise of 3. More importantly, the biosensor presented excellent ability to discriminate the perfectly complementary target and the mismatched stand. This strategy could be conveniently extended for detection of other biomolecules. To the best of our knowledge, this is the first application of bionic catalysis of porphyrin as detection probe and opens new opportunities for sensitive detection of biorecognition events.

  18. Long-range electron transfer in porphyrin-containing [2]-rotaxanes: tuning the rate by metal cation coordination.

    Science.gov (United States)

    Andersson, Mikael; Linke, Myriam; Chambron, Jean-Claude; Davidsson, Jan; Heitz, Valérie; Hammarström, Leif; Sauvage, Jean-Pierre

    2002-04-24

    A series of [2]-rotaxanes has been synthesized in which two Zn(II)-porphyrins (ZnP) electron donors were attached as stoppers on the rod. A macrocycle attached to a Au(III)-porphyrin (AuP+) acceptor was threaded on the rod. By selective excitation of either porphyrin, we could induce an electron transfer from the ZnP to the AuP+ unit that generated the same ZnP*+-AuP* charge-transfer state irrespective of which porphyrin was excited. Although the reactants were linked only by mechanical or coordination bonds, electron-transfer rate constants up to 1.2x10(10) x s(-1) were obtained over a 15-17 A edge-to-edge distance between the porphyrins. The resulting charge-transfer state had a relatively long lifetime of 10-40 ns and was formed in high yield (>80%) in most cases. By a simple variation of the link between the reactants, viz. a coordination of the phenanthroline units on the rotaxane rod and ring by either Ag+ or Cu+, we could enhance the electron-transfer rate from the ZnP to the excited 3AuP+. We interpret our data in terms of an enhanced superexchange mechanism with Ag+ and a change to a stepwise hopping mechanism with Cu+, involving the oxidized Cu(phen)22+ unit as a real intermediate. When the ZnP unit was excited instead, electron transfer from the excited 1ZnP to AuP+ was not affected, or even slowed, by Ag+ or Cu+. We discuss this asymmetry in terms of the different orbitals involved in mediating the reaction in an electron- and a hole-transfer mechanism. Our results show the possibility to tune the rates of electron transfer between noncovalently linked reactants by a convenient modification of the link. The different effect of Ag+ and Cu+ on the rate with ZnP and AuP+ excitation shows an additional possibility to control the electron-transfer reactions by selective excitation. We also found that coordination of the Cu+ introduced an energy-transfer reaction from 1ZnP to Cu(phen)2+ (k = 5.1x10(9) x s(-1)) that proceeded in competition with electron

  19. A novel reusable platinum nanocatalyst

    International Nuclear Information System (INIS)

    Zhou Weiqiang; Wang Jing; Wang Chuanyi; Du Yukou; Xu Jingkun; Yang Ping

    2010-01-01

    Recyclability of noble metal catalysts is a challenging issue when dealing with their industrial applications. Smart pH-sensitive Pt nanoparticles were successfully prepared for the first time by using octa(N,N-diacetic acid phenylamine)silsesquioxane (OAPAS) as a macromolecular protective agent. As-prepared Pt nanoparticles can self-aggregate or redisperse by only changing the pH of the system solution. In the weak acidic or alkaline solution (pH > 4.0), the Pt nanoparticles dispersed homogenously; while in the acidic solution (pH = 2.5), they self-aggregated. The dynamic self-aggregation and redispersion processes of the Pt nanoparticles driven by pH changes were revealed by transmission electron microscopy measurements. Electrocatalytic experiments proved that the platinum nanoparticles as a recyclable catalyst showed excellent activity for the hydrogenation of aldehyde after runs of five times. Such platinum nanoparticles are thereby anticipated to have great potential functioning as 'smart' catalysts for industrial applications.

  20. De novo design and engineering of functional metal and porphyrin-binding protein domains

    Science.gov (United States)

    Everson, Bernard H.

    In this work, I describe an approach to the rational, iterative design and characterization of two functional cofactor-binding protein domains. First, a hybrid computational/experimental method was developed with the aim of algorithmically generating a suite of porphyrin-binding protein sequences with minimal mutual sequence information. This method was explored by generating libraries of sequences, which were then expressed and evaluated for function. One successful sequence is shown to bind a variety of porphyrin-like cofactors, and exhibits light- activated electron transfer in mixed hemin:chlorin e6 and hemin:Zn(II)-protoporphyrin IX complexes. These results imply that many sophisticated functions such as cofactor binding and electron transfer require only a very small number of residue positions in a protein sequence to be fixed. Net charge and hydrophobic content are important in determining protein solubility and stability. Accordingly, rational modifications were made to the aforementioned design procedure in order to improve its overall success rate. The effects of these modifications are explored using two `next-generation' sequence libraries, which were separately expressed and evaluated. Particular modifications to these design parameters are demonstrated to effectively double the purification success rate of the procedure. Finally, I describe the redesign of the artificial di-iron protein DF2 into CDM13, a single chain di-Manganese four-helix bundle. CDM13 acts as a functional model of natural manganese catalase, exhibiting a kcat of 0.08s-1 under steady-state conditions. The bound manganese cofactors have a reduction potential of +805 mV vs NHE, which is too high for efficient dismutation of hydrogen peroxide. These results indicate that as a high-potential manganese complex, CDM13 may represent a promising first step toward a polypeptide model of the Oxygen Evolving Complex of the photosynthetic enzyme Photosystem II.

  1. Electronic and electrochemical properties of platinum(II) and platinum-mercury-carboxylato complexes containing 2-Me2NCH2C6H4, 2,6-(Me2NCH2)2C6H3- and 2-Me2NC6H4CH2 - ligands

    NARCIS (Netherlands)

    Koten, G. van; Ploeg, A.F.M.J. van der; Schmitz, J.E.J.; Linden, J.G.M. van der

    1982-01-01

    The organoplatinum(II) compounds [{2, 6-(Me{2}NCH{2}){2}C{6}H{3}}PtBr] and cis-[(C-N){2}Pt] (C-N = 2-Me{2}NCH{2}C{6}H{4}, 2-Me{2}NC{6}H{4}CH{2}) can be chemically irreversibly oxidized in the potential range 1.00 to 1.35 V vs. an Ag/AgCl electrode, whereas the organoplatinum@?mercury complexes

  2. Photophysical properties of novel Porphyrin-Flavin Dyads

    International Nuclear Information System (INIS)

    Stark, S.

    2001-10-01

    Photosynthesis belongs to the fundamentals of life on earth, therefore it is an important matter in natural sciences. The basic principle of photosynthesis is the transformation of solar light into chemical energy. The starting steps of photosynthesis are light-induced energy- and electron-transfer-steps with singular efficiency. One attempt to enlighten the molecular processes involved is to synthesize simpler model systems with similar properties. Important research goals are the dependencies of light-induced processes on distance and orientation of donor and acceptor. A second aim next to the clarification of the molecular conditions of photosynthesis is to create molecular light-driven machines. The most simple so-called biomimetic model system consists of an electron-donor connected to an electron-acceptor via a spacer-group. This simplest form is also referred to as dyad. Beyond dyads far more complicated compounds have been introduced consisting of several donors and/or acceptors, so-called triads, tetrads, pentads etc. Usually porphyrin serves as electron-donor. Next to chinones several other electron-acceptors are used, e.g. anthracene, pyromellitimide and fullerene. Artificial photosynthetic centers are often more stable and/or the excited states are easier to detect compared to the natural photosynthetic center. The photophysical characteristics of four dyads are reported in this work. The dyads consist of porphyrin (either free-base or zinc-metallated) and flavin, connected by different spacers. These dyads reveal photo-induced electron transfer from porphyrin to flavin and energy-transfer in the reversed direction with different efficiencies. The object of the study is the dependency of these processes on the structural features. The spacer of the dyads 1a-1c is an aromatic bridge which leads to well defined donor-acceptor distances. Because of this structure conjugation through the spacer is increased, whereas the absorption in the visible and near UV

  3. Tunable photophysical processes of porphyrin macrocycles on the surface of ZnO nanoparticles

    KAUST Repository

    Parida, Manas R.

    2015-01-23

    We investigated the impact of the molecular structure of cationic porphyrins on the degree of electrostatic interactions with zinc oxide nanoparticles (ZnO NPs) using steady-state and time-resolved fluorescence and transient absorption spectroscopy. Our results demonstrate that the number of cationic pyridinium units has a crucial impact on the photophysics of the porphyrin macrocycle. Fluorescence enhancement, relative to initial free porphyrin fluorescence, was found to be tuned from 3.4 to 1.3 times higher by reducing the number of cationic substituents on the porphyrin from 4 to 2. The resulting enhancement of the intensity of the fluorescence is attributed to the decrease in the intramolecular charge transfer (ICT) character between the porphyrin cavity and its meso substituent. The novel findings reported in this work provide an understanding of the key variables involved in nanoassembly, paving the way toward optimizing the interfacial chemistry of porphyrin-ZnO NP assembly for photodynamic therapy and energy conversion.

  4. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, L.C.; Ishida, Takanobu.

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  5. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, Leonard C. [State Univ. of New York (SUNY), Stony Brook, NY (United States); Ishida, Takanobu [State Univ. of New York (SUNY), Stony Brook, NY (United States)

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between -0.24 and +1.25 VSCE while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-ρ-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  6. Local Electric Field Effects on Rhodium-Porphyrin and NHC-Gold Catalysts

    Science.gov (United States)

    2015-01-05

    AFRL-OSR-VA-TR-2015-0023 (NII) - Local Electric Field Effects on Rhodium -Porphyrin and NHC-Gold Catalysts MATTHEW KANAN LELAND STANFORD JUNIOR UNIV...Effects on Rhodium -Porphyrin and NHC-Gold Catalysts Principal Investigator: Matthew W. Kanan Project Publications: 1. “An Electric Field–Induced Change...Stanford University Grant/Contract Title The full title of the funded effort. (NII)-Local Electric Field Effects on Rhodium -Porphyrin and NHC-Gold

  7. Mechanism of Platinum Derivatives Induced Kidney Injury

    Directory of Open Access Journals (Sweden)

    Feifei YAN

    2015-09-01

    Full Text Available Platinum derivatives are the most widely used chemotherapeutic agents to treat solid tumors including ovarian, head and neck, and testicular germ cell tumors, lung cancer, and colorectal cancer. Two major problems exist, however, in the clinic use of platinum derivatives. One is the development of tumor resistance to the drug during therapy, leading to treatment failure. The other is the drug’s toxicity such as the cisplatin’s nephrotoxicity, which limits the dose that can be administered. This paper describes the mechanism of platinum derivatives induced kidney injury.

  8. Studies on the distribution of platinum in tumour-bearing rats after the administration of platinum co-ordination complexes used in cancer chemotherapy

    International Nuclear Information System (INIS)

    Zeisler, R.; Lux, F.; Beck, W.

    1979-01-01

    Platinum co-ordination complexes like dichlorodiamineplatinum(II) (DDP) feature broad spectrum antitumour activity which, however, is marred by a certain toxicity related especially to renal tubular damage. The activity of such drugs depends on the chemical structure of the complexes, with changes in the ligands resulting in changes in their antitumour activity and toxicity. Assessments of the biological and toxicological effects of recently synthesized complexes must include distribution studies of platinum in the body. It is demonstrated that instrumental neutron activation analysis can be used for these studies because of its accuracy, precision and the low detection limit for platinum (approximately equal to 2 ng), when a standardized method is used. The time-dependent retention of platinum was determined in blood, liver, kidneys and cells of ascitic Walker 256 carcinosarcoma in tumour-bearing rats and controls after the administration of the cis-Pt(Gly-Gly-0Et) 2 Cl 2 complex. Two series of experiments, one with the therapeutic amount of the drug (80 mg/kg body weight) and one low-dose experiment with 1/100 of this amount, were carried out. The results of both experiments are discussed with regard to changes in the platinum concentration with time (0-48 h) in the different samples. From the data a selective uptake of the drug by the tumour cells, causing their destruction, is deduced. Because this drug has shown excellent antitumour activity, this observed selectivity suggests promise for its application in cancer chemotherapy, although platinum retention is still found in the kidneys, which might cause renal tubular damage. This latter aspect requires further clinical research to evaluate fully its effects. (author)

  9. Controllable deposition of platinum nanoparticles on single-wall carbon nanohorns as catalyst for direct methanol fuel cells.

    Science.gov (United States)

    Niu, Ben; Xu, Wei; Guo, Zhengduo; Zhou, Nengzhi; Liu, Yang; Shi, Zujin; Lian, Yongfu

    2012-09-01

    Uniform and well dispersed platinum nanoparticles were successfully deposited on single-walled carbon nanohorns with the assistance of 4,4-dipydine and ion liquids, respectively. In particular, the size of platinum nanoparticles could be controlled in a very narrow range (2.2 to 2.5 nm) when ion liquids were applied. The crystalline nature of these platinum nanoparticles was confirmed by high resolution transmission electron microscopy observation and X-ray power diffraction analysis, and two species of platinum Pt(0) and Pt(II) were detected by X-ray photoelectron spectroscopy. Electrochemical studies revealed that thus obtained nanocomposites had much better electrocatalytic activity for the methanol oxidation than those prepared with carbon nanotubes as supporter.

  10. Dye linked conjugated homopolymers: using conjugated polymer electroluminescence to optically pump porphyrin-dye emission

    DEFF Research Database (Denmark)

    Nielsen, K.T.; Spanggaard, H.; Krebs, Frederik C

    2004-01-01

    . Electroluminescent devices of the homopolymer itself and of the zinc-porphyrin containing polymer were prepared and the nature of the electroluminescence was characterized. The homopolymer segments were found to optically pump the emission of the zinc-porphyrin dye moities. The homopolymer exhibits blue......Zinc-porphyrin dye molecules were incorporated into the backbone of a conjugated polymer material by a method, which allowed for the incorporation of only one zinc-porphyrin dye molecule into the backbone of each conjugated polymer molecule. The electronic properties of the homopolymer were...

  11. Boronated porphyrins in NCT: Results with a new potent tumor localizer

    International Nuclear Information System (INIS)

    Kahl, S.B.; Koo, M.S.; Laster, B.H.; Fairchild, R.G.

    1988-01-01

    Several chemical methods are available for the solubilization of boronated porphyrins. We have previously reported the tumor localization of nido carboranyl porphyrins in which the icosahedral carborane cages have been opened to give B 9 C 2 anions. One of these species has shown tumor boron levels of nearly 50 μg B/g when delivered by week-long subcutaneous infusions. We report here recent in vivo experiments with a new, highly water-soluble porphyrin based on the hematoporphyrin-type of compound in which aqueous solubility is achieved using the two propionic acid side chains of the ''natural'' porphyrin frame. 7 refs

  12. Peripherally Metalated Porphyrins with Applications in Catalysis, Molecular Electronics and Biomedicine.

    Science.gov (United States)

    Longevial, Jean-François; Clément, Sébastien; Wytko, Jennifer A; Ruppert, Romain; Weiss, Jean; Richeter, Sébastien

    2018-04-24

    Porphyrins are conjugated, stable chromophores with a central core that binds a variety of metal ions and an easily functionalized peripheral framework. By combining the catalytic, electronic or cytotoxic properties of selected transition metal complexes with the binding and electronic properties of porphyrins, enhanced characteristics of the ensemble are generated. This review article focuses on porphyrins bearing one or more peripheral transition metal complexes and discusses their potential applications in catalysis or biomedicine. Modulation of the electronic properties and intramolecular communication through coordination bond linkages in bis-porphyrin scaffolds is also presented. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.R.; Foger, K.; Breakspere, R.J.

    1979-05-01

    Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts was studied with 0.9-3Vertical Bar3< platinum on silica gel, aerosil, sodium and lanthanum Y zeolites, and ..gamma..-alumina, and on aerosil-supported gold-platinum alloys containing 2, 10, 24, 33, and 85Vertical Bar3< gold. Surface enrichment with gold in the alloy systems, as derived from hydrogen adsorption data and predicted from surface enrichment theory and electron microscopic measurements of particle size, were in good agreement, which indicated that equilibrium was achieved by the thermal treatment (oxygen at 573/sup 0/K, hydrogen at 620/sup 0/K, repeated cycles) used. Hydrogen spillover to gold was observed at the higher hydrogen pressures tested on the alloys with high gold content, and to the zeolite supports. The temperature-programed desorption profiles were independent of gold content, which indicated that gold acts only as diluent, and that isolated surface platinum atoms become populated with hydrogen atoms either by hydrogen atom spillover from platinum ensembles to gold and from the gold to the isolated platinum, and/or by adsorption of a molecule directly on the isolated platinum and chemisorption of one H atom at an adjacent gold atom. The distribution of surface platinum ensembles was evaluated by a computer simulation method.

  14. Hydrogenation of hexene over platinum on alumina vs. platinum in a Na-Y zeolite

    International Nuclear Information System (INIS)

    Miner, R.S. Jr.; Ione, K.G.; Namba, S.; Turkevich, J.

    1978-01-01

    In order to study the efficacy of zeolites as supports, several platinum H--Y zeolites were prepared by ion exchanging an H--Y zeolite with Pt(NH 3 ) 4 Cl 2 and reducing these products with hydrazine hydrate (A, B, C). Another preparation was made by adsorbing 32-A platinum sol on the zeolite crystallites (D). These catalysts were studied for hydrogenation and isomerization of hexene-1, ethylene hydrogenation, hydrogen chemisorption, and poison titration. They were compared with monodisperse Pt (32 A diameter) on alumina. A marked difference was found between the behavior of hexene-1 with the platinum-in-zeolite and with the platinum-on-alumina

  15. Characterization of functionalised porphyrin films using synchrotron radiation

    International Nuclear Information System (INIS)

    Arima, V.; Matino, F.; Thompson, J.; Del Sole, R.; Mele, G.; Vasapollo, G.; Cingolani, R.; Rinaldi, R.; Blyth, R.I.R.

    2005-01-01

    Porphyrins and C 60 are strategic materials for the fabrication of nanoscale molecular devices by virtue of their optical, photo-electro-chemical and chemical properties. We have developed procedures to immobilise cobalt tetra-butyl-phenyl porphyrins (CoTBPPs) on gold surfaces via ligation to self-assembled monolayers of aromatic aminothiophenols (4-ATP). We have used synchrotron radiation photoemission and near-edge X-ray absorption, NEXAFS, to characterise such films, both in their native state, and with ligated fulleropyrrolidines N-methyl-2-(p-pyridyl)-3,4-fulleropyrrolidine (Py-C 60 ), forming charge-separation complexes which may have applications in solar cells. While photoemission spectra appear dominated by the individual CoTBPP and Py-C 60 components, we observe an apparent signature of charge separation in fulleropyrrolidine NEXAFS spectra

  16. Enhanced solar energy collection in porphyrin based photoconversion schemes

    Science.gov (United States)

    Gust, D.; Moore, T. A.

    1983-02-01

    A series of carotenoporphyrins whose conformations varied from folded (with the carotenoid (PI)-electron system stacked over that of the porphyrin) to extended (with the two chromophores widely separated) were studied. The conformations were determined by high resolution proton NMR studies. Laser flash spectroscopy revealed triplet energy transfer from porphyrin to carotenoid. Three distinct pathways for such transfer were discovered: (1) static through space transfer which does not require significant intramolecular motions; (2) dynamic through space transfer mediated by intramolecular motions; (3) triplet transfer mediated by the chemical bonds joining the chromophores. pulse radiolysis and fluorescence quenching of these ethers and related carotenoporphyrins revealed electron transfer in the systems. It is demonstrated that the natural carotenoid functions of photoprotection from singlet oxygen damage and antenna function can be mimicked by synthetic molecules, and therefore, in principle can be applied to artificial solar energy conversion systems.

  17. Characterization of functionalised porphyrin films using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Arima, V. [National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Universita di Lecce Via Arnesano, 73100 Lecce (Italy)]. E-mail: valentina.arima@unile.it; Matino, F. [National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Universita di Lecce Via Arnesano, 73100 Lecce (Italy); Thompson, J. [National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Universita di Lecce Via Arnesano, 73100 Lecce (Italy); Del Sole, R. [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, via per Arnesano, 73100 Lecce (Italy); Mele, G. [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, via per Arnesano, 73100 Lecce (Italy); Vasapollo, G. [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, via per Arnesano, 73100 Lecce (Italy); Cingolani, R. [National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Universita di Lecce Via Arnesano, 73100 Lecce (Italy); Rinaldi, R. [National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Universita di Lecce Via Arnesano, 73100 Lecce (Italy); Blyth, R.I.R. [National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Universita di Lecce Via Arnesano, 73100 Lecce (Italy)

    2005-07-30

    Porphyrins and C{sub 60} are strategic materials for the fabrication of nanoscale molecular devices by virtue of their optical, photo-electro-chemical and chemical properties. We have developed procedures to immobilise cobalt tetra-butyl-phenyl porphyrins (CoTBPPs) on gold surfaces via ligation to self-assembled monolayers of aromatic aminothiophenols (4-ATP). We have used synchrotron radiation photoemission and near-edge X-ray absorption, NEXAFS, to characterise such films, both in their native state, and with ligated fulleropyrrolidines N-methyl-2-(p-pyridyl)-3,4-fulleropyrrolidine (Py-C{sub 60}), forming charge-separation complexes which may have applications in solar cells. While photoemission spectra appear dominated by the individual CoTBPP and Py-C{sub 60} components, we observe an apparent signature of charge separation in fulleropyrrolidine NEXAFS spectra.

  18. Synthesis and anion binding properties of porphyrins and related compounds

    KAUST Repository

    Figueira, Flávio

    2016-12-02

    Over the last two decades the preparation of pyrrole-based receptors for anion recognition has attracted considerable attention. In this regard porphyrins, phthalocyanines and expanded porphyrins have been used as strong and selective receptors while the combination of those with different techniques and materials can boost their applicability in different applications as chemosensors and extracting systems. Improvements in the field, including the synthesis of this kind of compounds, can contribute to the development of efficient, cheap, and easy-to-prepare anion receptors. Extensive efforts have been made to improve the affinity and selectivity of these compounds and the continuous expansion of related research makes this chemistry even more promising. In this review, we summarize the most recent developments in anion binding studies while outlining the strategies that may be used to synthesize and functionalize these type of macrocycles. © 2016 World Scientific Publishing Company.

  19. Facile Preparation of Hybrid Zinc Porphyrin Dendrimer Using Coordination Complex

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Go-Eun; Shin, Eun Ju [Sunchon National University, Suncheon (Korea, Republic of)

    2016-03-15

    Porphyrins and metalloporphyrins have been investigated extensively due to their important role in natural photosynthesis, strong absorption in visible region, good light-harvesting properties, unique photophysical and electrochemical properties, and the development of simple synthetic routes for various derivatives. Dendrimers have globular structure with branches of repeating units and wide diversity of the architecture because their size, shape, and functionalities can be tailored. Numerous dendrimers have been designed and synthesized for various applications ranging from catalyst to drug delivery. Both pyridine dendrons Py-PD and Py-AD were successfully coordinated at axial position on central zinc metal cation in zinc porphyrin dendrimers ZnP-AD, ZnP-AD2, or ZnP-AD4. Therefore, it was proven that the formation of axial coordination complex between metal-centered dendrimer and ligand-containing dendron provides another facile method for the preparation of new hybrid dendrimer.

  20. Emulating porphyrins with a rippled multivacancy graphene system

    Science.gov (United States)

    Mombrú, Dominique; Faccio, Ricardo; Mombrú, Alvaro W.

    2018-04-01

    The interaction between a complex porphyrin-like system formed by an iron atom and multivacant graphene layer and O2, CO and CO2 molecules is studied, using Density Functional Theory (DFT) calculations. The multivacancy graphene system used for this study, consists in the removal of a 1,4-dimethybenzene-like moiety, in a 6 × 6 supercell. This removal and the structural optimization subsequently performed, yield to a biaxial vacancy, where the location of an iron atom embedded in it, lead to a system with resemblance to iron-porphyrin systems. This similar structure could be used to form complexes where gas molecules are allowed to interact with these iron-octavacant graphene systems. The study focuses on the structure of the system and the net magnetic moment for different gas molecules: O2, CO2 and CO. Rippling in the vacant graphene is enhanced through this interaction.

  1. VB Platinum Tile & Carpet, Inc. Information Sheet

    Science.gov (United States)

    VB Platinum Tile & Carpet, Inc. (the Company) is located in Bristow, Virginia. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Washington, DC.

  2. Platinum-Resistor Differential Temperature Sensor

    Science.gov (United States)

    Kolbly, R. B.; Britcliffe, M. J.

    1985-01-01

    Platinum resistance elements used in bridge circuit for measuring temperature difference between two flowing liquids. Temperature errors with circuit are less than 0.01 degrees C over range of 100 degrees C.

  3. Acid-base-controlled stereoselective metalation of overhanging carboxylic acid porphyrins: consequences for the formation of heterobimetallic complexes.

    Science.gov (United States)

    Le Gac, Stéphane; Najjari, Btissam; Dorcet, Vincent; Roisnel, Thierry; Fusaro, Luca; Luhmer, Michel; Furet, Eric; Halet, Jean-François; Boitrel, Bernard

    2013-08-12

    Overhanging carboxylic acid porphyrins have revealed promising ditopic ligands offering a new entry in the field of supramolecular coordination chemistry of porphyrinoids. Notably, the adjunction of a so-called hanging-atop (HAT) Pb(II) cation to regular Pb(II) porphyrin complexes allowed a stereoselective incorporation of the N-core bound cation, and an allosterically controlled Newton's cradle-like motion of the two Pb(II) ions also emerged from such bimetallic complexes. In this contribution, we have extended this work to other ligands and metal ions, aiming at understanding the parameters that control the HAT Pb(II) coordination. The nature of the N-core bound metal ion (Zn(II), Cd(II)), the influence of the deprotonation state of the overhanging COOH group and the presence of a neutral ligand on the opposite side (exogenous or intramolecular), have been examined through (1)H NMR spectroscopic experiments with the help of radiocrystallographic structures and DFT calculations. Single and bis-strap ligands have been considered. They all incorporate a COOH group hung over the N-core on one side. For the bis-strap ligands, either an ester or an amide group has been introduced on the other side. In the presence of a base, the mononuclear Zn(II) or Cd(II) complexes incorporate the carbonyl of the overhanging carboxylate as apical ligand, decreasing its availability for the binding of a HAT Pb(II). An allosteric effector (e.g., 4-dimethylaminopyridine (DMAP), in the case of a single-strap ligand) or an intramolecular ligand (e.g., an amide group), strong enough to compete with the carbonyl of the hung COO(-), is required to switch the N-core bound cation to the opposite side with concomitant release of the COO(-), thereby allowing HAT Pb(II) complexation. In the absence of a base, Zn(II) or Cd(II) binds preferentially the carbonyl of the intramolecular ester or amide groups in apical position rather than that of the COOH. This better preorganization, with the

  4. Supramolecular Ferric Porphyrins as Cyanide Receptors in Aqueous Solution

    Science.gov (United States)

    2011-01-01

    All fundamental data about binding of the cyanide to a supramolecular complex composed of a per-O-methylated β-cyclodextrin dimer having an imidazole linker (Im3CD) and an anionic ferric porphyrin (Fe(III)TPPS) indicate that the Fe(III)TPPS/Im3CD complex is much better as an cyanide receptor in vivo than hydroxocobalamin, whose cyanide binding ability is lowered by its strong binding to serum proteins in the blood. PMID:24900285

  5. Photoinduced electron transfer within porphyrin-cyclodextrin conjugates

    Czech Academy of Sciences Publication Activity Database

    Lang, Kamil; Král, V.; Kapusta, P.; Kubát, Pavel; Vašek, P.

    2002-01-01

    Roč. 43, - (2002), s. 4919-4922 ISSN 0040-4039 R&D Projects: GA ČR GA203/99/1163; GA ČR GA203/01/0634; GA ČR GA203/02/1483 Institutional research plan: CEZ:AV0Z4032918 Keywords : porphyrin-cyclodextrin * chiral aggregate * quenching Subject RIV: CA - Inorganic Chemistry Impact factor: 2.357, year: 2002

  6. Chemistry of supramolecular systems containing porphyrins and metal complexes

    OpenAIRE

    Araki, Koiti; Toma, Henrique Eisi

    2002-01-01

    Supramolecular chemistry is expected to keep a high developing pace in the next years, giving support to the advancement of molecular devices and nanotechnology. In this sense, porphyrins and their analogues should play a significant role as a consequence of their catalytic, electrocatalytic, photochemical and photoelectrochemical properties. In this review we focused on our own strategy based on coordination chemistry for the design and build-up of supermolecules and supramolecular structure...

  7. Porphyrin-based Nanostructure-Dependent Photodynamic and Photothermal Therapies

    Science.gov (United States)

    Jin, Cheng S.

    This thesis presents the investigation of nanostructure-dependent phototherapy. We reviewed the liposomal structures for delivery of photosensitizers, and introduced a novel class of phototransducing liposomes called "porphysomes". Porphysomes are self-assembled from high packing density of pyropheophorbide alpha-conjugated phospholipids, resulting in extreme self-quenching of porphyrin fluorescence and comparable optical absorption to gold nanoparticles for high photothermal efficiency. We demonstrated this self-assembly of porphyrin-lipid conjugates converts a singlet oxygen generating mechanism (photodynamic therapy PDT activity) of porphyrin to photothermal mechanism (photothermal therapy PTT activity). The efficacy of porphysome-enhanced PTT was then evaluated on two pre-clinical animal models. We validated porphysome-enabled focal PTT to treat orthotopic prostate cancer using MRI-guided focal laser placement to closely mimic the current clinic procedure. Furthermore, porphysome-enabled fluorescence-guided transbronchial PTT of lung cancer was demonstrated in rabbit orthotopic lung cancer models, which led to the development of an ultra-minimally invasive therapy for early-stage peripheral lung cancer. On the other hand, the nanostructure-mediated conversion of PDT to PTT can be switched back by nanoparticle dissociation. By incorporating folate-conjugated phospholipids into the formulation, porphysomes were internalized into cells rapidly via folate receptor-mediated endocytosis and resulted in efficient disruption of nanostructures, which turned back on the photodynamic activity of densely packed porphyrins, making a closed loop of conversion between PDT and PTT. The multimodal imaging and therapeutic features of porphysome make it ideal for future personalized cancer treatments.

  8. Porphyrin doped vanadium pentoxide xerogel as electrode material

    Energy Technology Data Exchange (ETDEWEB)

    Anaissi, F.J.; Engelmann, F.M.; Araki, K.; Toma, H.E. [Sao Paulo Univ., SP (Brazil). Inst. de Quimica

    2003-04-01

    The lamellar composite material, VXG-TMPyP, obtained from the combination of cationic, water-soluble meso-(tetra-4-methyl-pyridinium)porphyrin (TMPyP) and vanadium pentoxide gel was investigated and employed as electrode modifying material. This material was isolated as a xerogel and characterized by X-ray diffraction, UV-Vis spectroscopy, cyclic voltammetry, spectro-electrochemistry and TG analysis. According to the X-ray diffraction data, the original VXG lamellar matrix framework is kept in the composite, evidencing a topotatic reaction. UV-Vis spectra indicated a strong interaction between VXG and TMPyP leading to the protonation of the porphyrin ring. In contrast with the vanadium oxide xerogel the new material is stable in water. The presence of the cationic porphyrin species in its structure turns it able to incorporate negatively charged ions, such as ferrocyanide and I{sup -}. The presence of the I{sub 2}/I{sup -} couple gives rise to a dramatic increase in the reversibility of the V{sup V/IV} process and in the charge capacity of the material. (authors)

  9. New approaches to novel boronated porphyrins for neutron capture therapy

    International Nuclear Information System (INIS)

    Kahl, S.B.

    1986-01-01

    The use of boon compounds in the treatment of human cancer is based on the unique ability of nonradioactive 10 B nuclei to absorb thermal neutrons. The prompt nuclear reactions, which occur in neutron absorption, deliver a dose of nearly 2.8 MeV only in the vicinity of boron-containing cells, since the nuclear garments produced (alpha particles and recoil lithium atoms) travel only 10 to 15 μm. The practical, clinical use of this technique to date has been limited by the authors inability to target boron-containing compounds specifically to tumor cells in amounts sufficient for therapy and in a chemical form that has an acceptable level of toxicity. Porphyrins are one important and large class of compounds that are known to accumulate in practically all tumor systems yet examined. Such site-specific accumulation is not known to be based on any currently identifiable selective transport mechanism and yet is observed for both natural and synthetic porphyrins. Tetraphenylporphine sulfonate (TPPS) has been shown by Fairchild et al. to be an ideal model compound for assessing porphyrin uptake, and suitably boronated tetraphenyl porphine might be expected to behave similarly. This report describes the synthesis, properties, and preliminary biodistribution of such compounds

  10. Antimicrobial activity of new porphyrins of synthetic and natural origin

    Science.gov (United States)

    Gyulkhandanyan, Grigor V.; Ghazaryan, Robert K.; Paronyan, Marina H.; Ulikhanyan, Ghukas I.; Gyulkhandanyan, Aram G.; Sahakyan, Lida A.

    2012-03-01

    Antimicrobial photodynamic inactivation has been successfully used against Gram (+) microorganisms, but most of the photosensitizers (PSs) on Gram (-) bacteria acts weakly. PSs are the natural or synthetic origin dyes, mainly porphyrins. We have synthesized more than 100 new cationic porphyrins and metalloporphyrins with different functional groups (hydroxyethyl, butyl, allyl, methallyl) and metals (cobalt, iron, copper, zinc, silver and other); from the nettle have also been purified pheophytin (a+b) and pheophytin (a) and have synthesized their Ag-and Zn-metalloporphyrins. It was found that in the dark (cytotoxic) mode, the most highly efficiency against microorganisms showed Agmetalloporphyrins of both types of porphyrins (synthetic and natural). Metalloporphyrin of natural origin Ag-pheophytin (a + b) is a strong antibacterial agent and causes 100% death as the Gram (+) microorganisms (St. aureus and MRSA) and the Gram (-) microorganisms (E.coli and Salmonella). It is established that for the destruction of Gram (+) and Gram (-) microorganisms in photodynamic mode cationic water-soluble synthetic metalloporphyrins, especially Zn-TBut4PyP, many times more effective than pheophytins. In vivo conditions on mice established that the best therapeutic activity against various strains of the microorganism St. aureus has the synthetic metalloporphyrin Ag-TBut4PyP. It is significantly more efficient than known drug "Chlorophyllipt" (2.5-3 times) and leads the survival rate of animals up to 50-60%.

  11. Interaction of cis-diamminediaquoplatinum(II) with adenosylcobalamin and alkylcobalamins

    Energy Technology Data Exchange (ETDEWEB)

    Hogenkamp, H P.C. [Univ. of Minnesota, Minneapolis; Kohlmiller, N A; Howsinger, R; Walker, T E; Matwiyoff, N A

    1980-01-01

    The interaction of cis-diamminediaquoplatinum(II) nitrate with adenosylcobalamin and a series of alkylcobalamins was studied by carbon-13 nuclear magnetic resonance spectroscopy and by electronic spectroscopy. With these cobalamins cis-(Pt(NH/sub 3/)/sub 2/(OH/sub 2/)/sub 2/)/sup 2 +/ forms adducts in which N(3) of the 5,6-methylbenzimidazole moiety is co-ordinated to platinum(II) rather than to cobalt(III) of the corrin. The chemical shifts of the 5'-methylene carbon of adenosylcobalamin-platinum adduct and of the Co-methyl carbon of the methylcobalamin-platinum adduct are characteristic of these cobalamins in the base-off form. Furthermore, these cobalamin-platinum complexes have visible spectra identical to those of the cobalamins in acidic solution. The /sup 13/C NMR spectrum of the adenosylcobalamin-platinum complex suggests the presence of a second adduct in which platinum(II) complexes are co-ordinated to both the N(3) of the 5,6-dimethylbenzimidazole nucleotide and to N(7) of the 5'-deoxyadenosyl moiety. The rate of the alkylcobalamin-platinum(II) adduct formation is determined by the strength of the cobalt(III)-5,6-dimethylbenzimidazole co-ordinate bond. Thus, adenosylcobalamin reacts much faster than adenosylepicobalamin to form the cobalamin-platinum(II) adduct.

  12. Iodometric determination of platinum(4) using amperometry

    International Nuclear Information System (INIS)

    Zakharov, V.A.; Gavva, N.F.; Songina, O.A.

    1976-01-01

    The possibility of iodometric determination of platinum (4) by amperometric titration has been investigated. Titration has been conducted at zero potential of platinum reference electrode. Voltampere curves and absorption spectra of the solutions have been recorded to elucidate the nature of platinum (4) interaction with iodide-ion. It has been established that in the case of small excess of iodide complex [PtI 6 ] 2- is formed. When there is a considerable excess of KI, platinum (4) is reduced to Pt(2) with the formation of [PtI 4 ] 2 - and liberation of free iodine. Optimal for iodometric titration of Pt(4) is the use of acetate ot phosphate background solution with pH 6-8 with respect to 1M KI which is attained by adding 3 g of solid KI to 20 ml of the solution being titrated. Under these conditions the limit of platinum detection is 0.5 mkg/ml. Determination of Pt (4) is not hindered by the presence of 200-fold amounts of Cr(6), V(5), and Ni(2) as well as by 20-10-fold amounts of As(5), Sb(5), Se(4), Te(4), Rh(3), and Ir(3), Determination is hindered by the presence of Pd(2), Fe(3), Ir(4), and Cu(2) which, however, can easily be overcome. The possibility has been shown of using the developed technique for analysis of platinum catalysts and alloys

  13. HAEM SYNTHASE AND COBALT PORPHYRIN SYNTHASE IN VARIOUS MICRO-ORGANISMS.

    Science.gov (United States)

    PORRA, R J; ROSS, B D

    1965-03-01

    1. The preparation of a crude extract of Clostridium tetanomorphum containing cobalt porphyrin synthase but little haem-synthase activity is described. 2. The properties of cobalt porphyrin synthase in the clostridial extracts is compared with the properties of a haem synthase present in crude extracts of the yeast Torulopsis utilis. 3. Cobalt porphyrin synthase in extracts of C. tetanomorphum inserts Co(2+) ions into the following dicarboxylic porphyrins in descending order of rate of insertion: meso-, deutero- and proto-porphyrins. Esterification renders meso- and deutero-porphyrins inactive as substrates. Neither the tetracarboxylic (coproporphyrin III) nor the octacarboxylic (uroporphyrin III) compounds are converted into cobalt porphyrins by the extract, but the non-enzymic incorporation of Co(2+) ions into these two porphyrins is rapid. These extracts are unable to insert Mn(2+), Zn(2+), Mg(2+) or Cu(2+) ions into mesoporphyrin. 4. Crude extracts of T. utilis readily insert both Co(2+) and Fe(2+) ions into deutero-, meso, and proto-porphyrins. Unlike the extracts of C. tetanomorphum, these preparations catalyse the insertion of Co(2+) ions into deuteroporphyrin more rapidly than into mesoporphyrin. This parallels the formation of haems by the T. utilis extract. 5. Cobalt porphyrin synthase is present in the particulate fraction of the extracts of C. tetanomorphum but requires a heat-stable factor present in the soluble fraction. This soluble factor can be replaced by GSH. 6. Cobalt porphyrin synthase in the clostridial extract is inhibited by iodoacetamide and to a smaller extent by p-chloromercuribenzoate and N-ethylmaleimide. The haem synthases of T. utilis and Micrococcus denitrificans are also inhibited by various thiol reagents.

  14. A one-dimensional polymeric cobalt(III–potassium complex with 18-crown-6, cyanide and porphyrinate ligands

    Directory of Open Access Journals (Sweden)

    Yassine Belghith

    2014-03-01

    Full Text Available The reaction of CoII(TpivPP {TpivPP is the dianion of 5,10,15,20-tetrakis[2-(2,2-dimethylpropanamidophenyl]porphyrin} with an excess of KCN salts and an excess of the 18-crown-6 in chlorobenzene leads to the polymeric title compound catena-poly[[dicyanido-2κ2C-(1,4,7,10,13,16-hexaoxacyclooctadecane-1κ6O{μ3-(2α,2β-5,10,15,20-tetrakis[2-(2,2-dimethylpropanamidophenyl]porphyrinato-1κO5:2κ4N,N′,N′′,N′′′:1′κO15}cobalt(IIIpotassium] dihydrate], {[CoK(CN2(C12H24O6(C64H64N8O4]·2H2O}n. The CoIII ion lies on an inversion center, and the asymmetric unit contains one half of a [CoIII(2α,2β-TpivPP(CN2]− ion complex and one half of a [K(18-C-6]+ counter-ion (18-C-6 is 1,4,7,10,13,16-hexaoxacyclooctadecane, where the KI ion lies on an inversion center. The CoIII ion is hexacoordinated by two C-bonded axial cyanide ligands and the four pyrrole N atoms of the porphyrin ligand. The KI ion is chelated by the six O atoms of the 18-crown-6 molecule and is further coordinated by two O atoms of pivalamido groups of the porphyrin ligands, leading to the formation of polymeric chains running along [011]. In the crystal, the polymeric chains and the lattice water molecules are linked by N—H...O and O—H...N hydrogen bonds, as well as weak C—H...O, O—H...π and C—H...π interactions into a three-dimensional supramolecular architecture.

  15. Efficient sensitization of dye-sensitized solar cells by novel triazine-bridged porphyrin-porphyrin dyads.

    Science.gov (United States)

    Zervaki, Galateia E; Roy, Mahesh S; Panda, Manas K; Angaridis, Panagiotis A; Chrissos, Emmanouel; Sharma, Ganesh D; Coutsolelos, Athanassios G

    2013-09-03

    Two novel porphyrin-porphyrin dyads, the symmetrical Zn[Porph]-Zn[Porph] (2) and unsymmetrical Zn[Porph]-H2[Porph] (4), where Zn[Porph] and H2[Porph] are the metalated and free-base forms of 5-(4-aminophenyl)-10,15,20-triphenylporphyrin, respectively, in which two porphyrin units are covalently bridged by 1,3,5-triazine, have been synthesized via the stepwise amination of cyanuric chloride. The dyads are also functionalized by a terminal carboxylic acid group of a glycine moiety attached to the triazine group. Photophysical measurements of 2 and 4 showed broaden and strengthened absorptions in their visible spectra, while electrochemistry experiments and density functional theory calculations revealed negligible interaction between the two porphyrin units in their ground states but appropriate frontier orbital energy levels for use in dye-sensitized solar cells (DSSCs). The 2- and 4-based solar cells have been fabricated and found to exhibit power conversion efficiencies (PCEs) of 3.61% and 4.46%, respectively (under an illumination intensity of 100 mW/cm(2) with TiO2 films of 10 μm thickness). The higher PCE value of the 4-based DSSC, as revealed by photovoltaic measurements (J-V curves) and incident photon-to-current conversion efficiency (IPCE) spectra of the two cells, is attributed to its enhanced short-circuit current (J(sc)) under illumination, high open-circuit voltage (V(oc)), and fill factor (FF) values. Electrochemical impedance spectra demonstrated shorter electron-transport time (τd), longer electron lifetime (τe), and high charge recombination resistance for the 4-based cell, as well as larger dye loading onto TiO2.

  16. Activation analysis for platinum in gold and metals of the platinum group through 199Au

    International Nuclear Information System (INIS)

    Foerster, H.

    1976-01-01

    Platinum was determined in gold and in metals of the platinum group through 199 Au by activation analysis. The matrix was separated at the end of irradiation before the daughter nuclide was formed. Gold was separated by extraction with MIBK from 1

  17. New carbon-carbon linked amphiphilic carboranyl-porphyrins as boron neutron capture agents

    International Nuclear Information System (INIS)

    Vicente, M.G.H.; Wickramasinghe, A.; Shetty, S.J.; Smith, K.M.

    2000-01-01

    Novel amphiphilic carboranyl-porphyrins have been synthesized for Boron Neutron Capture Therapy (BNCT). These compounds have carbon-carbon bonds between the carborane residues and the porphyrin meso-phenyl groups, and contain 28-31% boron by weight . (author)

  18. A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes.

    Science.gov (United States)

    Ushimaru, Richiro; Nishimura, Takuho; Iwatsuki, Toshiki; Naka, Hiroshi

    2017-01-01

    A fluorinated cobalt(III) porphyrin complex [Co(TPFPP)NTf 2 ·2C 2 H 5 OH, where TPFPP=5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, Tf=CF 3 SO 2 ] promotes hydroalkoxylation of alkynes to give acetals in good to excellent yields. The acetals can be directly functionalized with nucleophiles in a one-pot procedure.

  19. Ultrafast electron injection at the cationic porphyrin-graphene interface assisted by molecular flattening

    KAUST Repository

    Aly, Shawkat Mohammede; Parida, Manas R.; Alarousu, Erkki; Mohammed, Omar F.

    2014-01-01

    The steady-state and femtosecond (fs) time-resolved data clearly demonstrate that the charge transfer (CT) process at the porphyrin-graphene carboxylate (GC) interfaces can be tuned from zero to very sufficient and ultrafast by changing the electronic structure of the meso unit and the redox properties of the porphyrin cavity. This journal is © the Partner Organisations 2014.

  20. To what extent can charge localization influence electron injection efficiency at graphene-porphyrin interfaces?

    KAUST Repository

    Parida, Manas R.

    2015-04-28

    Controlling the electron transfer process at donor- acceptor interfaces is a research direction that has not yet seen much progress. Here, with careful control of the charge localization on the porphyrin macrocycle using β -Cyclodextrin as an external cage, we are able to improve the electron injection efficiency from cationic porphyrin to graphene carboxylate by 120% . The detailed reaction mechanism is also discussed.

  1. Formation and thermodynamic stability of (polymer + porphyrin) supramolecular structures in aqueous solutions

    International Nuclear Information System (INIS)

    Costa, Viviana C.P. da; Hwang, Barrington J.; Eggen, Spencer E.; Wallace, Megan J.; Annunziata, Onofrio

    2014-01-01

    Highlights: • Thermodynamic stability of a (polymer + porphyrin) supramolecular structure was characterized. • Isothermal titration calorimetry provided two ways to determine reaction enthalpies. • Exothermic (polymer + porphyrin) binding competes with porphyrin self-association. • (Polymer + porphyrin) binding is entropically favored with respect to porphyrin self-association. • Spectral shifts show importance of porphyrin central hydrogens in polymer binding. - Abstract: Optical properties of porphyrins can be tuned through (polymer + porphyrin) (host + guest) binding in solution. This gives rise to the formation of supramolecular structures. In this paper, the formation, thermodynamic stability and spectroscopic properties of (polymer + porphyrin) supramolecular structures and their competition with porphyrin self-association were investigated by both isothermal titration calorimetry (ITC) and absorption spectroscopy. Specifically, reaction enthalpies and equilibrium constants were measured for meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS) self-association and TPPS binding to the polymer poly(vinylpyrrolidone) (PVP, 40 kg/mol) in aqueous solutions at pH 7 and three different temperatures (12, 25 and 37 °C). ITC, compared to spectroscopic techniques, provides two independent means to determine reaction enthalpies: direct measurements and Van’t Hoff plot. This was used as a criterion to assess that (1) self-association of TPPS is limited to the formation of dimers and (2) TPPS binds to PVP in its monomeric state only. The formation of TPPS dimers and (PVP + TPPS) supramolecular structures are both enthalpically driven. However, (polymer + porphyrin) binding was found to be entropically favored compared to dimerization. Furthermore, the reaction enthalpies of these two processes significantly depend on temperature. This behavior was attributed to hydrophobic interactions. Finally, the limiting absorption spectra of monomeric, dimeric and polymer

  2. Excitation energy deactivation funnel in 3-substituted BODIPY-porphyrin conjugate

    International Nuclear Information System (INIS)

    Nguyen, Nguyen Tran; Verbelen, Bram; Leen, Volker; Waelkens, Etienne; Dehaen, Wim; Kruk, Mikalai

    2016-01-01

    BODIPYs absorb in the visible region which is complementary to that of porphyrins and therefore can be suggested as promising antenna groups to improve the light-harvesting potential of porphyrins. A boron-dipyrromethene dye was combined at the 3-position with a Zn-porphyrin to afford a conjugate. The fluorescence of the conjugate was found to originate from the BODIPY moiety independently of the excitation wavelength due to an unique set of energy transfer rates between the BODIPY and Zn-porphyrin moieties. The fluorescence intensity was shown to be tunable over a wide range using the solvent properties. This feature makes the studied BODIPY-porphyrin conjugate a promising compound for the design of new photochromic devices.

  3. Excitation energy deactivation funnel in 3-substituted BODIPY-porphyrin conjugate

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Nguyen Tran [Chemistry Department, University of Education, The University of DaNang, Ton Duc Thang 459, Da Nang (Viet Nam); Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven (Belgium); Verbelen, Bram; Leen, Volker [Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven (Belgium); Waelkens, Etienne [Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Box 901, 3000 Leuven (Belgium); Dehaen, Wim, E-mail: wim.dehaen@kuleuven.be [Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven (Belgium); Kruk, Mikalai, E-mail: m.kruk@belstu.by [Belarusian State Technological University, Physics Department, Sverdlov Str., 13a, Minsk 220006 (Belarus)

    2016-11-15

    BODIPYs absorb in the visible region which is complementary to that of porphyrins and therefore can be suggested as promising antenna groups to improve the light-harvesting potential of porphyrins. A boron-dipyrromethene dye was combined at the 3-position with a Zn-porphyrin to afford a conjugate. The fluorescence of the conjugate was found to originate from the BODIPY moiety independently of the excitation wavelength due to an unique set of energy transfer rates between the BODIPY and Zn-porphyrin moieties. The fluorescence intensity was shown to be tunable over a wide range using the solvent properties. This feature makes the studied BODIPY-porphyrin conjugate a promising compound for the design of new photochromic devices.

  4. Fusing porphyrins with polycyclic aromatic hydrocarbons and heterocycles for optoelectronic applications

    Science.gov (United States)

    Thompson, Mark E.; Diev, Viacheslav; Hanson, Kenneth; Forrest, Stephen R.

    2015-08-18

    A compound that can be used as a donor material in organic photovoltaic devices comprising a non-activated porphyrin fused with one or more non-activated polycyclic aromatic rings or one or more non-activated heterocyclic rings can be obtained by a thermal fusion process. The compounds can include structures of Formula I: ##STR00001## By heating the reaction mixture of non-activated porphyrins with non-activated polycyclic aromatic rings or heterocyclic rings to a fusion temperature and holding for a predetermined time, fusion of one or more polycyclic rings or heterocyclic rings to the non-activated porphyrin core in meso,.beta. fashion is achieved resulting in hybrid structures containing a distorted porphyrin ring with annulated aromatic rings. The porphyrin core can be olygoporphyrins.

  5. Push-Pull Type Porphyrin Based Sensitizers: The Effect of Donor Structure on the Light-Harvesting Ability and Photovoltaic Performance

    KAUST Repository

    Qi, Qingbiao; Li, Renzhi; Luo, Jie; Zheng, Bin; Huang, Kuo-Wei; Wang, Peng; Wu, Jishan

    2015-01-01

    Push-pull type porphyrin-based sensitizers have become promising candidates for high-efficiency dye sensitized solar cells (DSCs). It is of importance to understand the fundamental structure-physical property-photovoltaic performance relationships by varying the donor and acceptor moieties. In this work, two new porphyrin-based sensitizers, WW-7 and WW-8, were synthesized and compared with the known sensitizer YD20. All the three dyes have the same porphyrin core and acceptor group (ethynylbenzoic acid) but their donor groups vary from the triphenylamine in YD20 to meso-diphenylaminoanthracene in WW-7 to N-phenyl carbazole in WW-8. Co(II/III)-based DSC device characterizations revealed that WW-7 showed enhanced light harvesting ability in comparison to YD20 with improved incident photon-to-collected electron conversion efficiencies (IPCEs). As a result, WW-7 displayed much higher short circuit current (Jsc: 13.54 mA cm-2) and open-circuit voltage (Voc: 0.829 V), with a power conversion efficiency (η) as high as 7.7%. Under the same conditions, YD20 cell exhibited a power conversion efficiency of 6.6% and the dye WW-8 showed even lower efficiency (η = 4.6%). Detailed physical measurements and theoretic calculations were conducted to understand the difference and reveal how three different donor structures affect their molecular orbital profile, light-harvesting ability, energy level alignment, and eventually the photovoltaic performance.

  6. Electroreduction of CO 2 Catalyzed by a Heterogenized Zn–Porphyrin Complex with a Redox-Innocent Metal Center

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yueshen [Department; Energy; Jiang, Jianbing [Department; Energy; Weng, Zhe [Department; Energy; Wang, Maoyu [School; Broere, Daniël L. J. [Department; Zhong, Yiren [Department; Energy; Brudvig, Gary W. [Department; Energy; Feng, Zhenxing [School; Wang, Hailiang [Department; Energy

    2017-07-26

    Transition-metal-based molecular complexes are a class of catalyst materials for electrochemical CO2 reduction to CO that can be rationally designed to deliver high catalytic performance. One common mechanistic feature of these electrocatalysts developed thus far is an electrogenerated reduced metal center associated with catalytic CO2 reduction. Here we report a heterogenized zinc–porphyrin complex (zinc(II) 5,10,15,20-tetramesitylporphyrin) as an electrocatalyst that delivers a turnover frequency as high as 14.4 site–1 s–1 and a Faradaic efficiency as high as 95% for CO2 electroreduction to CO at -1.7 V vs the standard hydrogen electrode in an organic/water mixed electrolyte. While the Zn center is critical to the observed catalysis, in situ and operando X-ray absorption spectroscopic studies reveal that it is redox-innocent throughout the potential range. Cyclic voltammetry indicates that the porphyrin ligand may act as a redox mediator. Chemical reduction of the zinc–porphyrin complex further confirms that the reduction is ligand-based and the reduced species can react with CO2. This represents the first example of a transition-metal complex for CO2 electroreduction catalysis with its metal center being redox-innocent under working conditions.

  7. Push-Pull Type Porphyrin Based Sensitizers: The Effect of Donor Structure on the Light-Harvesting Ability and Photovoltaic Performance

    KAUST Repository

    Qi, Qingbiao

    2015-06-23

    Push-pull type porphyrin-based sensitizers have become promising candidates for high-efficiency dye sensitized solar cells (DSCs). It is of importance to understand the fundamental structure-physical property-photovoltaic performance relationships by varying the donor and acceptor moieties. In this work, two new porphyrin-based sensitizers, WW-7 and WW-8, were synthesized and compared with the known sensitizer YD20. All the three dyes have the same porphyrin core and acceptor group (ethynylbenzoic acid) but their donor groups vary from the triphenylamine in YD20 to meso-diphenylaminoanthracene in WW-7 to N-phenyl carbazole in WW-8. Co(II/III)-based DSC device characterizations revealed that WW-7 showed enhanced light harvesting ability in comparison to YD20 with improved incident photon-to-collected electron conversion efficiencies (IPCEs). As a result, WW-7 displayed much higher short circuit current (Jsc: 13.54 mA cm-2) and open-circuit voltage (Voc: 0.829 V), with a power conversion efficiency (η) as high as 7.7%. Under the same conditions, YD20 cell exhibited a power conversion efficiency of 6.6% and the dye WW-8 showed even lower efficiency (η = 4.6%). Detailed physical measurements and theoretic calculations were conducted to understand the difference and reveal how three different donor structures affect their molecular orbital profile, light-harvesting ability, energy level alignment, and eventually the photovoltaic performance.

  8. Unsymmetrical Mesoporphyrinic Complexes of Copper (II and Zinc (II. Microwave-Assisted Synthesis, Spectral Characterization and Cytotoxicity Evaluation

    Directory of Open Access Journals (Sweden)

    Rica Boscencu

    2011-06-01

    Full Text Available New unsymmetrical mesoporphyrinic complexes, namely 5-(4-hydroxyphenyl-10,15,20–tris-(4-carboxymethylphenyl–21,23-Zn(II-porphine and 5-(4-hydroxyphenyl-10,15,20–tris-(4-carboxymethylphenyl–21,23-Cu(II-porphine, were synthesized using a microwave irradiation method. The structures of the porphyrinic complexes were confirmed using FT-IR, UV–Vis, EPR and NMR spectral data. The spectral absorption and emission properties of the porphyrinic complexes were studied in organic solvents of different polarities and the influence of solvent polarity on the wavelengths of the absorbance and fluorescence band maxima is described. The cytotoxicity evaluation of the porphyrinic complexes was performed on human colon adenocarcinoma cell line HT29 for different doses and incubation times. The obtained result indicates a lack of or low toxicity for both compounds, thus recommending them for further testing in light activation protocols.

  9. Platinum uptake from chloride solutions using biosorbents

    Directory of Open Access Journals (Sweden)

    Mehmet Hakan Morcali

    2013-04-01

    Full Text Available Present work investigates platinum uptake from synthetically prepared, dilute platinum-bearing solutions using biomass residues, i.e. pistachio nut shell and rice husk, which are abundant in Turkey, and provides a comparison between these two biosorbents. Effects of the different uptake parameters, sorbent dosage, contact time, temperature and pH of solution on platinum uptake (% were studied in detail on a batch sorption. Before the pistachio nut shell was activated, platinum uptake (% was poor compared to the rice husk. However, after the pistachio nut shell was activated at 1000 °C under an argon atmosphere, the platinum uptake (% increased two-fold. The pistachio nut shell (original and activated and rice husk were shown to be better than commercially available activated carbon in terms of adsorption capacity. These two sorbents have also been characterized by FTIR and SEM. Adsorption equilibrium data best complied with the Langmuir isotherm model. Maximum adsorption capacities, Qmax, at 25 °C were found to be 38.31 and 42.02 mg.g- 1for the activated pistachio nut shell and rice husk, respectively. Thermodynamic calculations using the measured ∆H°, ∆S° and ∆G° values indicate that the uptake process was spontaneous and endothermic. The experimental data were shown to be fit the pseudo-second-order kinetic model.

  10. Two dimensional self-assembly zinc porphyrin and zinc phthalocyanine heterojunctions with record high power conversion efficiencies

    Science.gov (United States)

    Yu, Junting; Jiang, Zhou; Hao, Yifan; Zhu, Qianhong; Zhao, Mingliang; Jiang, Xue; Zhao, Jijun

    2018-06-01

    Compared to inorganic solar cells, the power conversion efficiencies (PCEs) of organic solar cells are much lower, but they are compensated by many merits such as lower cost, less weight, and tunable structures, making them prospective for further applications. Porphyrin and phthalocyanine are the two most significant materials for organic solar cells due to their strong light-absorbing properties and semiconductor characteristics. However, there is little research on the 2D heterojunction solar cells based on these two materials, meanwhile the PCEs of them are still low. Here we have self-assembled several 2D zinc porphyrins (ZnPors) and performed first-principles simulation to demonstrate their good stability, suitable light harvesting, and high charge carrier mobility. By perfectly matching lattice constants and molecular energy levels between those 2D ZnPors and our previous proposed zinc phthalocyanines (ZnPcs), 11 type-II organic heterojunctions are constructed to further improve their charge separation capability. Those advantages endow 2D ZnPors and ZnPcs appreciable PCEs for solar cells. Among them, the theoretical PCE of 2D ZnPors/ZnPcs heterojunctions achieves as high as 19.84%, which exceeds all reported organic solar cells, and even approaches the PCEs of inorganic solar cells. These results indicate that our 2D ZnPors and 2D ZnPcs are good candidate materials for future organic solar cells.

  11. Novel platinum black electroplating technique improving mechanical stability.

    Science.gov (United States)

    Kim, Raeyoung; Nam, Yoonkey

    2013-01-01

    Platinum black microelectrodes are widely used as an effective neural signal recording sensor. The simple fabrication process, high quality signal recording and proper biocompatibility are the main advantages of platinum black microelectrodes. When microelectrodes are exposed to actual biological system, various physical stimuli are applied. However, the porous structure of platinum black is vulnerable to external stimuli and destroyed easily. The impedance level of the microelectrode increases when the microelectrodes are damaged resulting in decreased recording performance. In this study, we developed mechanically stable platinum black microelectrodes by adding polydopamine. The polydopamine layer was added between the platinum black structures by electrodeposition method. The initial impedance level of platinum black only microelectrodes and polydopamine added microelectrodes were similar but after applying ultrasonication the impedance value dramatically increased for platinum black only microelectrodes, whereas polydopamine added microelectrodes showed little increase which were nearly retained initial values. Polydopamine added platinum black microelectrodes are expected to extend the availability as neural sensors.

  12. Heterobimetallic porphyrin complexes displaying triple dynamics: coupled metal motions controlled by constitutional evolution.

    Science.gov (United States)

    Le Gac, Stéphane; Fusaro, Luca; Roisnel, Thierry; Boitrel, Bernard

    2014-05-07

    A bis-strap porphyrin ligand (1), with an overhanging carboxylic acid group on each side of the macrocycle, has been investigated toward the formation of dynamic libraries of bimetallic complexes with Hg(II), Cd(II), and Pb(II). Highly heteroselective metalation processes occurred in the presence of Pb(II), with Hg(II) or Cd(II) bound out-of-plane to the N-core and "PbOAc" bound to a carboxylate group of a strap on the opposite side. The resulting complexes, 1(Hg)·PbOAc and 1(Cd)·PbOAc, display three levels of dynamics. The first is strap-level (interactional dynamics), where the PbOAc moiety swings between the left and right side of the strap owing to a second sphere of coordination with lateral amide functions. The second is ligand-level (motional dynamics), where 1(Hg)·PbOAc and 1(Cd)·PbOAc exist as two degenerate states in equilibrium controlled by a chemical effector (AcO(-)). The process corresponds to a double translocation of the metal ions according to an intramolecular migration of Hg(II) or Cd(II) through the N-core, oscillating between the two equivalent overhanging carbonyl groups, coupled to an intermolecular pathway for PbOAc exchanging between the two equivalent overhanging carboxylate groups (N-core(up) ⇆ N-core(down) coupled to strap(down) ⇆ strap(up), i.e., coupled motion #1 in the abstract graphic). The third is library-level (constitutional dynamics), where a dynamic constitutional evolution of the system was achieved by the successive addition of two chemical effectors (DMAP and then AcO(-)). It allowed shifting equilibrium forward and backward between 1(Hg)·PbOAc and the corresponding homobimetallic complexes 1(Hg2)·DMAP and 1(Pb)·PbOAc. The latter displays a different ligand-level dynamics, in the form of an intraligand coupled migration of the Pb(II) ions (N-core(up) ⇆ strap(up) coupled to strap(down) ⇆ N-core(down), i.e., coupled motion #2 in the abstract graphic). In addition, the neutral "bridged" complexes 1HgPb and 1Cd

  13. Magnetic Circular Dichroism of Porphyrin Lanthanide M3+ Complexes

    Czech Academy of Sciences Publication Activity Database

    Andrushchenko, Valery; Padula, Daniele; Zhivotova, E.; Yamamoto, S.; Bouř, Petr

    2014-01-01

    Roč. 26, č. 10 (2014), s. 655-662 ISSN 0899-0042 R&D Projects: GA ČR GA13-03978S; GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:GA AV ČR(CZ) M200550902 Institutional support: RVO:61388963 Keywords : magnetic circular dichroism * lanthanides * porphyrin complexes * density functional theory * sum over state computations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.886, year: 2014

  14. Polystyrene nanofiber materials modified with an externally bound porphyrin photosensitizer

    Czech Academy of Sciences Publication Activity Database

    Henke, P.; Lang, Kamil; Kubát, Pavel; Sýkora, Jan; Šlouf, Miroslav; Mosinger, Jiří

    2013-01-01

    Roč. 5, č. 9 (2013), s. 3776-3783 ISSN 1944-8244 R&D Projects: GA ČR GAP208/10/1678; GA ČR GBP208/12/G016; GA ČR GA13-12496S Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:61389013 Keywords : nanofiber * porphyrin * singlet oxygen * adsorption * photooxidation * antibacterial Subject RIV: CA - Inorganic Chemistry; CD - Macromolecular Chemistry (UMCH-V); CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 5.900, year: 2013

  15. Effect of amine substituted at ortho and para positions on the electrochemical and electrocatalytic properties of cobalt porphyrins self-assembled on glassy carbon surface

    International Nuclear Information System (INIS)

    Muthukumar, Palanisamy; John, S. Abraham

    2014-01-01

    Highlights: •The self-assembly of ortho and para isomers of Co(II)aminoporphyrin on GCE was studied. •The electrochemical and electrocatalytic properties were examined. •The Co(II)MTpAP showed two redox waves whereas Co(II)MToAP showed a single redox peak. •Both the SAMs greatly catalyzed the dioxigen reduction when compared to GCE. -- Abstract: This work addresses the influence of amine group substituted at para and ortho positions of the phenyl groups on the electrochemical and electrocatalytic properties of cobalt porphyrins self-assembled on glassy carbon electrode (GCE). We have synthesized meso-tetra(para-aminophenyl)porphyrinatocobalt(II) (Co(II)MTpAP) and meso-tetra(ortho-aminophenyl)porphyrinatocobalt(II) (Co(II)MToAP) and were self-assembled on GCE through Michael addition of nucleophilic amine with olefinic GCE surface. Cyclic voltammetry, reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques were employed to confirm the formation of the self-assembled monolayers (SAMs) of Co(II)MTpAP and Co(II)MToAP on GCEs. Interestingly, the SAM of Co(II)MTpAP in 0.1 M H 2 SO 4 shows two redox waves at 0.37 and 0.60 V whereas the SAM of Co(II)MToAP shows a single redox wave at 0.32 V, indicating the influence of amine group position in the phenyl ring on the redox chemistry of porphyrin. In contrary, the SAMs of the corresponding free base porphyrins prepared under identical conditions show a single redox wave around 0.36 V. Thus, we have assigned the redox wave at 0.37 V to Co(II)Por 1− /Co(II)Por 2− and 0.60 V to Co III/II redox couples for the SAM of Co(II)MTpAP. In the case of Co(II)MToAP, we have assigned the redox wave at 0.32 V due to both Co(II)Por 1− /Co(II)Por 2− and Co III/II . The surface coverage estimated from the charge consumed for the oxidation of Co III/II was used to study the thermodynamics and kinetics of Co(II)MTpAP and Co(II)MToAP self-assembled on GCE. Further, the electrochemical reduction of dioxygen

  16. Nitrite reduction on a multimetallic porphyrin/polyoxotungstate layer-by-layer modified electrodes

    International Nuclear Information System (INIS)

    García, Macarena; Honores, Jessica; Quezada, Diego; Díaz, Carlos; Dreyse, Paulina; Celis, Freddy; Kubiak, Clifford P.; Canzi, Gabriele; Guzmán, Fernando

    2016-01-01

    Electro and photoelectrochemical reduction of nitrite in aqueous solution was studied using a multielectrocatalysts modified ITO electrode. ITO modification was carried out using the layer-by-layer (LBL) method, where sequential electrostatic assemblies were formed using a μ-(meso-5,10,15,20-tetra(pirydil)porphyrin)tetrakis{bis(bipyridine)chloride ruthenium (II)} [MTRP] n+ , coordinated in its central cavity with Mn(III), Zn(II) or Ni(II) as a cationic layer, and polyoxotungstate [SiW 12 O 40 ] 4− as the anionic layer. Electrochemical measurements and UV–vis spectroscopy were used to monitor the modification process. Optimal results were obtained when three layers were deposited onto the ITO surface and were stable in aqueous solution. The order of the multilayer formation was explored by comparing a modified electrode where [Zn(II)TRP] 4+ was the outermost layer with an electrode where [SiW 12 O 40 ] 4− was the outer layer. Results show that the best performing electrode is one with [SiW 12 O 40 ] 4− as the outer layer. Nitrite reduction on these electrode surfaces was studied in dark conditions and under light irradiation. Potential controlled electrolysis experiments were also performed, finding hydroxylamine, hydrazine and ammonia as the reduction products in dark conditions. Under light irradiation, only hydrazine and ammonia were found and, we observed an increase in the amount of obtained product. In this case, the electrolysis was carried out 150 mV less and half of time than in dark conditions. These results show that the combination of light and potential give rise to an improvement in the electrocatalytic properties of the modified electrodes. Continuous photolysis and IR spectroelectrochemical experiments were carried out to determinate the nature of this phenomena, evidencing the formation of an intermediary species between nitrite and [Mn(III)TRP] 5+.

  17. Interactions of tetracationic porphyrins with DNA and their effects on DNA cleavage

    Science.gov (United States)

    Lebedeva, Natalya Sh.; Yurina, Elena S.; Gubarev, Yury A.; Syrbu, Sergey A.

    2018-06-01

    The interaction of tetracationic porphyrins with DNA was studied using UV-Vis absorption, fluorescence spectroscopy and viscometry, and the particle sizes were determined. Аs cationic porphyrins, two isomer porphyrins, 3,3‧,3″,3‴-(5,10,15,20-Porphyrintetrayl)tetrakis(1-methylpyridinium) (TMPyP3) and 4,4‧,4″,4‴-(5,10,15,20-Porphyrintetrayl)tetrakis(1-methylpyridinium) (TMPyP4), were studied. They differ in the position of NCH3+ group in phenyl ring of the porphyrins and hence, in degree of freedom of rotation of the phenyl rings about the central macrocycle. It was found that intercalated complexes are formed at DNA/porphyrin molar ratios (R) of 2.2 and 3.9 for TMPyP3 и TMPyP4, respectively. Decreasing R up to 0.4 and 0.8 for TMPyP3 и TMPyP4, respectively, leads mainly to formation of outside complexes due to π-π stacking between the porphyrin chromophores interacting electrostatically with phosphate framework of DNA. Each type of the obtained complexes was characterized using Scatchard approach. It was ascertained that the affinity of TMPyP4 to DNA is stronger than TMPyP3, meanwhile the wedge effect of the latter is higher. The differences between the porphyrin isomers become more evident at irradiation of their complexes with DNA. It was established that irradiation of the intercalated complexes results in DNA fragmentation. In the case of TMPyP4, DNA fragments of different size are formed. The irradiation of the outside DNA/porphyrin complexes leads to cleavage of DNA (TMPyP3 and TMPyP4) and partial destruction of the complex due to photolysis of the porphyrin (TMPyP3).

  18. The impact of whole human blood on the kinetic inertness of platinum(iv) prodrugs - an HPLC-ICP-MS study.

    Science.gov (United States)

    Theiner, Sarah; Grabarics, Márkó; Galvez, Luis; Varbanov, Hristo P; Sommerfeld, Nadine S; Galanski, Markus; Keppler, Bernhard K; Koellensperger, Gunda

    2018-04-17

    The potential advantage of platinum(iv) complexes as alternatives to classical platinum(ii)-based drugs relies on their kinetic stability in the body before reaching the tumor site and on their activation by reduction inside cancer cells. In this study, an analytical workflow has been developed to investigate the reductive biotransformation and kinetic inertness of platinum(iv) prodrugs comprising different ligand coordination spheres (respectively, lipophilicity and redox behavior) in whole human blood. The distribution of platinum(iv) complexes in blood pellets and plasma was determined by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave digestion. An analytical approach based on reversed-phase (RP)-ICP-MS was used to monitor the parent compound and the formation of metabolites using two different extraction procedures. The ligand coordination sphere of the platinum(iv) complexes had a significant impact on their accumulation in red blood cells and on their degree of kinetic inertness in whole human blood. The most lipophilic platinum(iv) compound featuring equatorial chlorido ligands showed a pronounced penetration into blood cells and a rapid reductive biotransformation. In contrast, the more hydrophilic platinum(iv) complexes with a carboplatin- and oxaliplatin-core exerted kinetic inertness on a pharmacologically relevant time scale with notable amounts of the compound accumulated in the plasma fraction.

  19. Platinum recycling in the United States in 1998

    Science.gov (United States)

    Hilliard, Henry E.

    2001-01-01

    In the United States, catalytic converters are the major source of secondary platinum for recycling. Other sources of platinum scrap include reforming and chemical process catalysts. The glass industry is a small but significant source of platinum scrap. In North America, it has been estimated that in 1998 more than 20,000 kilograms per year of platinum-group metals from automobile catalysts were available for recycling. In 1998, an estimated 7,690 kilograms of platinum were recycled in the United States. U.S. recycling efficiency was calculated to have been 76 percent in 1998; the recycling rate was estimated at 16 percent.

  20. Outpatient desensitization in selected patients with platinum hypersensitivity reactions.

    Science.gov (United States)

    O'Malley, David M; Vetter, Monica Hagan; Cohn, David E; Khan, Ambar; Hays, John L

    2017-06-01

    Platinum-based chemotherapies are a standard treatment for both initial and recurrent gynecologic cancers. Given this widespread use, it is important to be aware of the features of platinum hypersensitivity reactions and the subsequent treatment of these reactions. There is also increasing interest in the development of desensitization protocols to allow patients with a history of platinum hypersensitivity to receive further platinum based therapy. In this review, we describe the management of platinum hypersensitivity reactions and the desensitization protocols utilized at our institution. We also describe the clinical categorizations utilized to triage patients to appropriate desensitization protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Electropolymerized supramolecular tetraruthenated porphyrins applied as a voltammetric sensor

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Monize M. da; Ribeiro, Gabriel H.; Faria, Anizio M. de; Bogado, Andre L.; Dinelli, Luis R., E-mail: dinelli@pontal.ufu.br [Universidade Federal de Uberlandia (UFU), Ituiutaba, MG (Brazil). Faculdade de Ciencias Integradas do Pontal; Batista, Alzir A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Quimica

    2013-11-15

    Porphyrin 5,10,15,20-Tetra(4-pyridyl)manganese(III), [Mn-TPyP(H{sub 2}O){sub 2}]PF{sub 6}, and electropolymerized supramolecular porphyrins (ESP), {l_brace}Mn-TPyP(H{sub 2}O){sub 2}[RuCl{sub 3}(dppb)]{sub 4}{r_brace}PF{sub 6} (dppb = 1,4-bis(diphenylphosphine)butane), were synthesized and characterized. A thin solid film of ESP was obtained on a glass carbon electrode surface by a cyclic voltammetry method. The peak current increased with the number of voltammetric cycles, which shows a typical behavior of the species being adsorbed on the surface of the electrode. Cyclic voltammetry was also employed for acetaminophen quantification using an ESP modified electrode. The modified electrode shows a linear relationship between the anodic peak current and the concentration of acetaminophen (in the rage 0.05 to 0.7 mmol L{sup -1}. The performance of the modified electrode was verified by the determination of acetaminophen in a commercial pharmaceutical product and the results were in good agreement with those obtained by a control HPLC method. (author)

  2. In vitro and in vivo analysis of boronated porphyrins

    International Nuclear Information System (INIS)

    Edwards, Benjamin; Matthews, Kristin; Hou, Yongjin; Vicente, M.G.H.; Autry-Conwell, Susan; James, Boggan

    2000-01-01

    New series of meso-phenylporphyrins linked through carbon-carbon bonds to nido-carboranyl groups, and containing 26-31% boron by weight, have been reported. Dark toxicity, photo-toxicity, and measurements of uptake and efflux were performed using mouse, rat, and human malignant cell lines. Drug uptake and retention by log phase cells are shown by spectrophotometry (porphyrins) and ICP-MS (boron) of cellular extracts to be concentration and time dependent, and to be influenced by plasma lipoproteins. Plasma pharmacokinetics and tissues biodistribution were studied in adult male Fisher 344 rats with bilateral subcutaneous 9L tumors injected (2.2 ml, 2 mM i.v.) with carboranyl porphyrin solutions. Whole blood, brain, liver, spleen, skin and tumors were collected at 2, 8, 18, 24 and 48 hours post-injection. Blood cells were separated from plasma and stored frozen with the other tissues. Tissue boron content was determined quantitatively by ICP-MS analysis following microwave digestion of carefully weighed samples. (author)

  3. Electron transfer reactions involving porphyrins and chlorophyll a

    International Nuclear Information System (INIS)

    Neta, P.; Scherz, A.; Levanon, H.

    1979-01-01

    Electron transfer reactions involving porphyrins (P) and quinones (Q) have been studied by pulse radiolysis. The porphyrins used were tetraphenylporphyrin (H 2 TPP), its tetracarboxy derivative (H 2 TCPP), the sodium and zinc compounds (Na 2 TPP and ZnTPP), and chlorophyll a (Chl a). These compounds were found to be rapidly reduced by electron transfer from (CH 3 ) 2 CO - . Reduction by (CH 3 ) 2 COH was rapid in aqueous solutions but relatively slow in i-PrOH solutions. Transient spectra of the anion radicals were determined and, in the case of H 2 TCPP - ., a pK = 9.7 was derived for its protonation. Electron-transfer reactions from the anion radical of H 2 TCPP to benzoquinone, duroquinone, 9,10-anthraquinone 2-sulfonate, and methylviologen occur in aqueous solutions with rate constants approx. 10 7 -10 9 M -1 s -1 which depend on the pH and the quinone reduction potential. Reactions of Na 2 TPP - ., ZnTPP - ., and Chl a - . with anthraquinone in basic i-PrOH solutions occur with rate constants approx. 10 9 M -1 s -1 . The spectral changes associated with these electron-transfer reactions as observed over a period of approx. 1 ms indicated, in some cases, the formation of an intermediate complex [P...Q - .]. 8 figures, 2 tables

  4. High-conductance surface-anchoring of a mechanically flexible platform-based porphyrin complex

    International Nuclear Information System (INIS)

    Hauptmann, Nadine; Buchmann, Kristof; Scheil, Katharina; Berndt, Richard; Groß, Lynn; Herrmann, Carmen; Schütt, Christian; Otte, Franziska L; Herges, Rainer

    2015-01-01

    The conductances of molecular model junctions comprising a triazatriangulenium platform with or without an ethynyl spacer and an upright Zn-porphyrin are probed with a low-temperature scanning probe microscope. The platform alone is found to be highly conductive. The ethynyl-linked Zn-porphyrin moiety reduces the conductance by three orders of magnitude and leads to an unexpected, non-monotonous variation of the force that was measured simultaneously at the tip of the microscope. Density functional theory calculations show that this variation results from an induced tilting of the porphyrin. (paper)

  5. On the enzymatic formation of platinum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Govender, Y.; Riddin, T. L. [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa); Gericke, M. [MINTEK (South Africa); Whiteley, C. G., E-mail: C.Whiteley@ru.ac.z [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa)

    2010-01-15

    A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 {sup o}C, respectively, a half-life stability of 36 min and a V{sub max} and K{sub m} of 3.57 nmol min{sup -1} mL{sup -1} and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H{sub 2}PtCl{sub 6}) at 1 or 2 mM with a K{sub i} value of 118 {mu}M. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 {sup o}C) afforded <10% bioreduction after 8 h while at conditions suitable for platinum nanoparticle formation (pH 9, 65 {sup o}C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

  6. Rockburst damage mechanism at Impala Platinum Mine

    CSIR Research Space (South Africa)

    Ledwaba, LS

    2012-05-01

    Full Text Available Impala Platinum Mine (Impala), situated north of the town of Rustenburg in the North West Province of South Africa, has experienced an increase in seismicity from ~841 seismic events in the year 2005 to ~1588 seismic events in 2008...

  7. Comparison of electron ionization and fast atom bombardment-mass spectrometry for the determination of nickel, vanadyl and free-base porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Castro, A.J.; Van Berkel, G.J.; Doolittle, F.G.; Filby, R.H. (Washington State Univ., Pullman (USA))

    1989-01-01

    Fast Atom Bombardment-Mass Spectrometry (FAB-MS) and Electron Ionization-Mass Spectrometry (EI-MS) at 12 and 70 eV, were used to obtain mass spectra of mesoporphyrin IX dimethylester (DME), tetraphenylporphyrin (TPP), octaethylporphyrin (OEP), and the metal-loporphyrins, Ni(DME), Ni(TPP), Ni(OEP), VO(TPP), VO(OEP), as well as a VO(II) porphyrin concentrate obtained from the New Albany oil shale bitumen (Mississippian-Devonian). A mixture of dithiothreitol/dithioerythritol (Magic Bullet) was used as the FAB matrix. Greater fragmentation of free-base and metalloporphyrins was observed in FAB mass spectra compared to the EI mass spectra. Adduct ions formed by addition of sulfur and a matrix molecule to the porphyrins were observed. In FAB spectra of the VO(II) complexes, loss of oxygen was noted. The FAB mass spectra of mixtures of VO(II) geoporphyrins are much more complex than corresponding EI mass spectra because of the greater fragmentation and the multiplicity of ions (M{sup +}, M + H, M + 2H, etc.) observed in the FAB mode. Using the matrices investigated, FAB is less suitable for EI for the mass spectrometric analysis of the geoporphyrins.

  8. A Porphyrin Complex as a Self-Conditioned Electrode Material for High-Performance Energy Storage.

    Science.gov (United States)

    Gao, Ping; Chen, Zhi; Zhao-Karger, Zhirong; Mueller, Jonathan E; Jung, Christoph; Klyatskaya, Svetlana; Diemant, Thomas; Fuhr, Olaf; Jacob, Timo; Behm, R Jürgen; Ruben, Mario; Fichtner, Maximilian

    2017-08-21

    The novel functionalized porphyrin [5,15-bis(ethynyl)-10,20-diphenylporphinato]copper(II) (CuDEPP) was used as electrodes for rechargeable energy-storage systems with an extraordinary combination of storage capacity, rate capability, and cycling stability. The ability of CuDEPP to serve as an electron donor or acceptor supports various energy-storage applications. Combined with a lithium negative electrode, the CuDEPP electrode exhibited a long cycle life of several thousand cycles and fast charge-discharge rates up to 53 C and a specific energy density of 345 Wh kg -1 at a specific power density of 29 kW kg -1 . Coupled with a graphite cathode, the CuDEPP anode delivered a specific power density of 14 kW kg -1 . Whereas the capacity is in the range of that of ordinary lithium-ion batteries, the CuDEPP electrode has a power density in the range of that of supercapacitors, thus opening a pathway toward new organic electrodes with excellent rate capability and cyclic stability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Stepwise transformation of the molecular building blocks in a porphyrin-encapsulating metal-organic material

    KAUST Repository

    Zhang, ZhenJie

    2013-04-24

    When immersed in solutions containing Cu(II) cations, the microporous metal-organic material P11 ([Cd4(BPT)4]·[Cd(C 44H36N8)(S)]·[S], BPT = biphenyl-3,4′,5-tricarboxylate) undergoes a transformation of its [Cd 2(COO)6]2- molecular building blocks (MBBs) into novel tetranuclear [Cu4X2(COO)6(S) 2] MBBs to form P11-Cu. The transformation occurs in single-crystal to single-crystal fashion, and its stepwise mechanism was studied by varying the Cd2+/Cu2+ ratio of the solution in which crystals of P11 were immersed. P11-16/1 (Cd in framework retained, Cd in encapsulated porphyrins exchanged) and other intermediate phases were thereby isolated and structurally characterized. P11-16/1 and P11-Cu retain the microporosity of P11, and the relatively larger MBBs in P11-Cu permit a 20% unit cell expansion and afford a higher surface area and a larger pore size. © 2013 American Chemical Society.

  10. Mechanism and efficiency of cell death of type II photosensitizers: effect of zinc chelation.

    Science.gov (United States)

    Pavani, Christiane; Iamamoto, Yassuko; Baptista, Maurício S

    2012-01-01

    A series of meso-substituted tetra-cationic porphyrins, which have methyl and octyl substituents, was studied in order to understand the effect of zinc chelation and photosensitizer subcellular localization in the mechanism of cell death. Zinc chelation does not change the photophysical properties of the photosensitizers (all molecules studied are type II photosensitizers) but affects considerably the interaction of the porphyrins with membranes, reducing mitochondrial accumulation. The total amount of intracellular reactive species induced by treating cells with photosensitizer and light is similar for zinc-chelated and free-base porphyrins that have the same alkyl substituent. Zinc-chelated porphyrins, which are poorly accumulated in mitochondria, show higher efficiency of cell death with features of apoptosis (higher MTT response compared with trypan blue staining, specific acridine orange/ethidium bromide staining, loss of mitochondrial transmembrane potential, stronger cytochrome c release and larger sub-G1 cell population), whereas nonchelated porphyrins, which are considerably more concentrated in mitochondria, triggered mainly necrotic cell death. We hypothesized that zinc-chelation protects the photoinduced properties of the porphyrins in the mitochondrial environment. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  11. Noninvasive estimation of bound and mobile platinum compounds in the kidney using a radiopharmacokinetic model

    International Nuclear Information System (INIS)

    Brechner, R.R.; D'Argenio, D.Z.; Dahalan, R.; Wolf, W.

    1986-01-01

    Nephrotoxicity remains a major limitation in the use of cisplatin [cis-diamminedichloroplatinum(II)]. Although several strategies are in use to limit this serious side effect, none is fully satisfactory. Classical pharmacokinetic studies of cisplatin have been based on blood and urine samples. As nephrotoxicity plays a significant role in the design of the therapeutic strategy, the kidneys should be considered as a separate state in any model formulated for ultimate control purposes. Previous studies of organ pharmacokinetics have relied on population measurements. The authors have developed an organ compartmental model from individual animal data obtained noninvasively. The eight-compartment model used to represent the distribution of cisplatin considers free and bound platinum in plasma, platinum in the erythrocytes, mobile and bound platinum in the kidneys, mobile and bound platinum in the tissues, and platinum in the urine. Data were collected from experiments with anesthetized female rats, after intravenous administration of [195mPt]cisplatin. Both arterial and bladder samples, and multiple images obtained with an Anger camera interfaced to a microcomputer were used. The model was estimated from individual data obtained after injection of a bolus of cisplatin (six animals). The model was validated by using it to predict data obtained from forcing the system with a different input function, a 0.5-h intravenous infusion (three animals). The results of this work show that it is possible to noninvasively study drug kinetics in organs that are not readily accessible to direct measurements in an individual, rather than relying on invasive measurements performed on a population.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Porphyrin metabolisms in human skin commensal Propionibacterium acnes bacteria: potential application to monitor human radiation risk.

    Science.gov (United States)

    Shu, M; Kuo, S; Wang, Y; Jiang, Y; Liu, Y-T; Gallo, R L; Huang, C-M

    2013-01-01

    Propionibacterium acnes (P. acnes), a Gram-positive anaerobic bacterium, is a commensal organism in human skin. Like human cells, the bacteria produce porphyrins, which exhibit fluorescence properties and make bacteria visible with a Wood's lamp. In this review, we compare the porphyrin biosynthesis in humans and P. acnes. Also, since P. acnes living on the surface of skin receive the same radiation exposure as humans, we envision that the changes in porphyrin profiles (the absorption spectra and/or metabolism) of P. acnes by radiation may mirror the response of human cells to radiation. The porphyrin profiles of P. acnes may be a more accurate reflection of radiation risk to the patient than other biodosimeters/biomarkers such as gene up-/down-regulation, which may be non-specific due to patient related factors such as autoimmune diseases. Lastly, we discuss the challenges and possible solutions for using the P. acnes response to predict the radiation risk.

  13. Thermodynamics of complex formation of natural iron(III)porphyrins with neutral ligands

    International Nuclear Information System (INIS)

    Lebedeva, Nataliya Sh.; Yakubov, Sergey P.; Vyugin, Anatoly I.; Parfenyuk, Elena V.

    2003-01-01

    Calorimetric titrations in benzene and chloroform at 298.15 K have been performed to give the complexes stability constants and the thermodynamic parameters for the complex formation of nature iron(III)porphyrins with pyridine. Stoichimetry of the complexes formed has been determined. It has been found that the thermodynamic parameters obtained depend on nature of peripheral substituents of the porphyrins. The estimation of the influence of Cl - and Ac - ions on the processes studied has been carried out. Using thermodynamic analysis method, the crystallsolvates of nature iron(III)porphyrins with benzene have been studied. Stoichiometry, thermal and energetic stability of the π-π-complexes formed have been determined. The data obtained have been used to the estimate solvent effect on the thermodynamic parameters of axial coordination of pyridine on the iron(III)porphyrins in benzene

  14. Functionalized porphyrin conjugate thin films deposited by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Iordache, S. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Popescu, A.C.; Popescu, C.E.; Dorcioman, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Ciucu, A.A. [University of Bucharest, Faculty of Chemistry, Bucharest (Romania); Balan, A.; Stamatin, I. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Fagadar-Cosma, E. [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazul Ave. 24, 300223-Timisoara (Romania); Chrisey, D.B. [Tulane University, Departments of Physics and Biomedical Engineering, New Orleans, LA 70118 (United States)

    2013-08-01

    We report on the deposition of nanostructured porphyrin-base, 5(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin thin films by matrix assisted pulsed laser evaporation onto silicon substrates with screen-printed electrodes. AFM investigations have shown that at 400 mJ/cm{sup 2} fluence a topographical transition takes place from the platelet-like stacking porphyrin-based nanostructures in a perpendicular arrangement to a quasi-parallel one both relative to the substrate surface. Raman spectroscopy has shown that the chemical structure of the deposited thin films is preserved for fluences within the range of 200–300 mJ/cm{sup 2}. Cyclic voltammograms have demonstrated that the free porphyrin is appropriate as a single mediator for glucose in a specific case of screen-printed electrodes, suggesting potential for designing a new class of biosensors.

  15. A New Synthesis of Porphyrins with Extended Conjugation and their Photophysics

    National Research Council Canada - National Science Library

    Ono, Noboru

    2005-01-01

    .... These molecules useful non-linear optical and optoelectronic properties. The contractor used a synthesis method based on the retro Diels-Alder reaction of porphyrins fused with bicyclo[2.2.2]octadiene units...

  16. A panchromatic anthracene-fused porphyrin sensitizer for dye-sensitized solar cells

    KAUST Repository

    Ball, James M.; Davis, Nicola K. S.; Wilkinson, James D.; Kirkpatrick, James; Teuscher, Joë l; Gunning, Robert; Anderson, Harry L.; Snaith, Henry J.

    2012-01-01

    The development of ruthenium-free sensitizers which absorb light over a broad range of the solar spectrum is important for improving the power conversion efficiency of dye-sensitized solar cells. Here we study three chemically tailored porphyrin

  17. Biodistribution, toxicity and efficacy of a boronated porphyrin for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Miura, Michiko; Micca, P.; Fairchild, R.; Slatkin, D.; Gabel, D.

    1992-01-01

    Boron-containing porphyrins may be useful for boron neutron capture therapy (BNCT) in the treatment of brain tumors. Porphyrins have been shown to accumulate in tumor tissue and to be essentially excluded from normal brain. However, problems of toxicity may prevent some boron-containing porphyrins from being considered for BNCT. The authors have synthesized the boronated porphyrin 2,4-bis-vinyl-o-nidocarboranyl-deuteroporphyrin IX (VCDP). Preliminary studies in tumor-bearing mice showed considerable uptake of boron at a total dose of 150 μg/gbw with low mortality. They now report that a total dose to mice of ∼ 275 μg VCDP/gbw administered in multiple intraperitoneal (ip) injections can provide 40-50μg B per gram of tumor with acceptable toxicity. Toxicity experiments and a preliminary trial of BNCT in mice given such doses are also reported

  18. Distribution of exogenous porphyrins in vivo; implications for neutron capture therapy

    International Nuclear Information System (INIS)

    Fairchild, R.G.; Gabel, D.; Hillman, M.; Watts, K.

    1982-01-01

    Endogenous porphyrins (HpD) are already in clinical use for phototherapy, in which red light is used to stimulate a cytotoxic response in tumors. The evident success, at least with superficial cancers, gives biological evidence of selective concentrations of porphyrins in tumors adequate for therapy. The authors have investigated, in addition, the biodistribution of a synthetic porphyrin (tetraphenylporphinesulfonate, or TPPS) in seven different animal tumor models. Their data, as well as those of others, indicate abundant accumulations of TPPS in tumor. If boronated analogs behave in the same way, boron concentrations would be up to 10 times that needed for therapy. Utilization of such porphyrin analogs in the neutron capture therapy (NCT) procedure is similar in concept to phototherapy currently being used clinically, with the distinct advantage of deeper tissue penetration produced by the activating neutrons

  19. Graphene and Carbon-Nanotube Nanohybrids Covalently Functionalized by Porphyrins and Phthalocyanines for Optoelectronic Properties.

    Science.gov (United States)

    Wang, Aijian; Ye, Jun; Humphrey, Mark G; Zhang, Chi

    2018-04-01

    In recent years, there has been a rapid growth in studies of the optoelectronic properties of graphene, carbon nanotubes (CNTs), and their derivatives. The chemical functionalization of graphene and CNTs is a key requirement for the development of this field, but it remains a significant challenge. The focus here is on recent advances in constructing nanohybrids of graphene or CNTs covalently linked to porphyrins or phthalocyanines, as well as their application in nonlinear optics. Following a summary of the syntheses of nanohybrids constructed from graphene or CNTs and porphyrins or phthalocyanines, explicit intraconjugate electronic interactions between photoexcited porphyrins/phthalocyanines and graphene/CNTs are introduced classified by energy transfer, electron transfer, and charge transfer, and their optoelectronic applications are also highlighted. The major current challenges for the development of covalently linked nanohybrids of porphyrins or phthalocyanines and carbon nanostructures are also presented. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Functionalized Nanostructures: Redox-Active Porphyrin Anchors for Supramolecular DNA Assemblies

    KAUST Repository

    Börjesson, Karl; Wiberg, Joanna; El-Sagheer, Afaf H.; Ljungdahl, Thomas; Må rtensson, Jerker; Brown, Tom; Nordén, Bengt; Albinsson, Bo

    2010-01-01

    , such as orientation, strength, homogeneity, and binding site size, was determined, suggesting that the porphyrin is well suited as a photophysical and redox-active lipid anchor, in comparison to the inert cholesterol anchor commonly used today. Furthermore

  1. Electrocatalytic miRNA Detection Using Cobalt Porphyrin-Modified Reduced Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Camille De Souza

    2014-06-01

    Full Text Available Metalated porphyrins have been described to bind nucleic acids. Additionally, cobalt porphyrins present catalytic properties towards oxygen reduction. In this work, a carboxylic acid-functionalized cobalt porphyrin was physisorbed on reduced graphene oxide, then immobilized on glassy carbon electrodes. The carboxylic groups were used to covalently graft amino-terminated oligonucleotide probes which are complementary to a short microRNA target. It was shown that the catalytic oxygen electroreduction on cobalt porphyrin increases upon hybridization of miRNA strand (“signal-on” response. Current changes are amplified compared to non-catalytic amperometric system. Apart from oxygen, no added reagent is necessary. A limit of detection in the sub-nanomolar range was reached. This approach has never been described in the literature.

  2. Functionalized Nanostructures: Redox-Active Porphyrin Anchors for Supramolecular DNA Assemblies

    KAUST Repository

    Börjesson, Karl

    2010-09-28

    We have synthesized and studied a supramolecular system comprising a 39-mer DNA with porphyrin-modified thymidine nucleosides anchored to the surface of large unilamellar vesicles (liposomes). Liposome porphyrin binding characteristics, such as orientation, strength, homogeneity, and binding site size, was determined, suggesting that the porphyrin is well suited as a photophysical and redox-active lipid anchor, in comparison to the inert cholesterol anchor commonly used today. Furthermore, the binding characteristics and hybridization capabilities were studied as a function of anchor size and number of anchoring points, properties that are of importance for our future plans to use the addressability of these redox-active nodes in larger DNA-based nanoconstructs. Electron transfer from photoexcited porphyrin to a lipophilic benzoquinone residing in the lipid membrane was characterized by steady-state and time-resolved fluorescence and verified by femtosecond transient absorption. © 2010 American Chemical Society.

  3. Electrical characteristic of spin coated Fe-Porphyrin on Cu substrates

    Energy Technology Data Exchange (ETDEWEB)

    Utari, E-mail: utari@ugm.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Kentingan Surakarta 57126 (Indonesia); Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Bulaksumur BLS 21 Yogyakarta 55281 (Indonesia); Kusumandari,; Purnama, Budi, E-mail: bpurnama@mipa.uns.ac.id [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Kentingan Surakarta 57126 (Indonesia); Mudasir [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Bulaksumur BLS 21 Yogyakarta 55281 (Indonesia); Abraha, Kamsul [Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Bulaksumur BLS 21 Yogyakarta 55281 (Indonesia)

    2016-06-17

    This paper describes the electrical-characteristics of Fe-Porphyrin thin films on Cu substrates. The thin layer samples used were deposited by spin coating methods on Cu-substrates at room temperature with and without induced magnetic field in the plane direction of the surface films. Fe-porphyrin was dissolved in chloroform and mixed with a magnetic stirrer for 60 min at a rotational speed of 200 rpm. The experimental results show that the mobility carrier charge of the Fe-Porphyrin layer with induced magnetic field during deposition has lower value than that without induced magnetic field case. The decrease of the mobility can be attribute to the change of the surface morphology in Fe-porphyrin films by means of increase in the nano-granular/nano-molecular size caused by the induce magnetic field.

  4. Acid-base and coordination properties of Meso-substituted porphyrins in nonaqueous solutions

    Science.gov (United States)

    Pukhovskaya, S. G.; Nam, Dao Tkhe; Fien, Chan Ding; Domanina, E. N.; Ivanova, Yu. B.; Semeikin, A. S.

    2017-09-01

    Acid-base and coordination properties of alkyl and aryl meso-substituted porphyrins are studied spectrophotometrically in nonaqueous solutions. It is found that the nature of the substituent greatly affects the basicity of ligands for porphyrins characterized by a flat structure of macrocycle. The electronic effects of substituents have a much weaker influence on the kinetics of complexing. These effects could be due to the opposite orientation of some factors: an increase in the basicity and stability of the N-H bonds of porphyrin reaction centers. Dissociation constants p K b of the cationic forms of meso-substituted derivatives of porphyrin are measured. The values of p K b are in good agreement with classic concepts of the nature of substituents, particularly those indirectly included in the macrocycle through phenyl buffer rings.

  5. Local Electronic Structure of a Single-Layer Porphyrin-Containing Covalent Organic Framework

    KAUST Repository

    Chen, Chen; Joshi, Trinity; Li, Huifang; Chavez, Anton D.; Pedramrazi, Zahra; Liu, Pei-Nian; Li, Hong; Dichtel, William R.; Bredas, Jean-Luc; Crommie, Michael F.

    2017-01-01

    We have characterized the local electronic structure of a porphyrin-containing single-layer covalent organic framework (COF) exhibiting a square lattice. The COF monolayer was obtained by the deposition of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde

  6. Spectral properties of porphyrins in the systems with layered silicates

    International Nuclear Information System (INIS)

    Ceklovsky, A.

    2009-03-01

    This work is focused on investigation of hybrid materials based on layered silicates, representing host inorganic component, and porphyrin dyes as organic guest. Aqueous colloidal dispersions, as well as thin solid films of layered silicate/porphyrin systems were studied. Modification of photophysical properties, such as absorption and fluorescence of molecules, adsorbed or incorporated in layered silicate hosts, were studied mainly to spread the knowledge about the environments suitable for incorporating aromatic compounds, providing photoactive properties of potential technological interest. TMPyP cations interact with the surfaces of layered silicates via electrostatic interactions. The extent of dye adsorption on colloidal particles of the silicates is influenced by the CEC values and swelling ability of silicates. Interaction of porphyrins with layered silicate hosts leads to significant changes of dye spectral properties. One of the key parameters that has a crucial impact on this interaction is the layer charge of silicate template. Other factors influence the resulting spectral properties of hybrid systems, such as the method of hybrid material preparation, the material's type (colloid, film), and the modification of the silicate host. Molecular orientation studies using linearly-polarized spectroscopies in VIS and IR regions revealed that TMPyP molecules were oriented in almost parallel fashion with respect to the silicate surface plane. Slightly higher values of the orientation angle of TMPyP transition moment were observed for the TMPyP/FHT system. Thus, flattening of the guest TMPyP molecules is the next important factor (mainly in the systems with lower layer charge), influencing its spectral properties upon the interaction with layered silicates. Fluorescence was effectively quenched in the systems based on solid films prepared from the high concentration of the dye (10-3 mol.dm-3). The quenching is most probably related to the structure of the

  7. Porphyrin molecules boost the sensitivity of epitaxial graphene for NH3 detection

    Science.gov (United States)

    Iezhokin, I.; den Boer, D.; Offermans, P.; Ridene, M.; Elemans, J. A. A. W.; Adriaans, G. P.; Flipse, C. F. J.

    2017-02-01

    The sensitivity of quasi-free standing epitaxial graphene for NH3 detection is strongly enhanced by chemical functionalization with cobalt porphyrins resulting in a detection limit well below 100 ppb. Hybridization between NH3 and cobalt porphyrins induces a charge transfer to graphene and results in a shift of the graphene Fermi-level as detected by Hall measurements and theoretically explained by electronic structure calculations.

  8. N-annulated perylene fused porphyrins with enhanced near-IR absorption and emission

    KAUST Repository

    Jiao, Chongjun

    2010-09-17

    N-Annulated perylene fused porphyrins 1 and 2 were synthesized by oxidative dehydrogenation using a Sc(OTf)3/DDQ system. These newly synthesized hybrid molecules are highly soluble in organic solvents and exhibit remarkably intense near-IR absorption, as well as detectable photoluminescence quantum yields, all of which are comparable to or even exceed those of either meso-β doubly linked porphyrin dimer/trimer or bis/tri-N-annulated rylenes. © 2010 American Chemical Society.

  9. Comparative VOCs sensing performance for conducting polymer and porphyrin functionalized carbon nanotubes based sensors

    Science.gov (United States)

    Datta, Kunal; Rushi, Arti; Ghosh, Prasanta; Shirsat, Mahendra

    2018-05-01

    We report sensors for detection of ethyl alcohol, a prominent volatile organic compound (VOC). Single walled carbon nanotubes were selected as main sensing backbone. As efficiency of sensor is dependent upon the choice of sensing materials, the performances of conducting polymer and porphyrin based sensors were compared. Chemiresistive sensing modality was adopted to observe the performance of sensors. It has been found that porphyrin based sensor shows higher affinity towards ethyl alcohol.

  10. Self-organization of porphyrin units induced by magnetic field during sol-gel polymerization.

    Science.gov (United States)

    Lerouge, Frédéric; Cerveau, Geneviève; Corriu, Robert J P; Stern, Christine; Guilard, Roger

    2007-04-21

    The use of a magnetic field as a controlling factor during the hydrolysis-polycondensation of porphyrin precursors substituted by Si(OR)(3) groups, induces a self-organization of porphyrin moieties due to the stacking of these units in the hybrid material and this study also confirms the effect of the magnetic field in the nano- and micrometric organization during the kinetically controlled polycondensation process.

  11. Enhancement of oxygen reduction at Fe tetrapyridyl porphyrin by pyridyl-N coordination to transition metal ions

    International Nuclear Information System (INIS)

    Maruyama, Jun; Baier, Claudia; Wolfschmidt, Holger; Bele, Petra; Stimming, Ulrich

    2012-01-01

    One of the promising candidates as noble-metal-free electrode catalysts for polymer electrolyte fuel cells (PEFCs) is a carbon material with nitrogen atoms coordinating iron ions embedded on the surface (Fe-N x moiety) as the active site, although the activity is insufficient compared to conventional platinum-based electrocatalysts. In order to obtain fundamental information on the activity enhancement, a simple model of the Fe-N x active site was formed by adsorbing 5,10,15,20-Tetrakis(4-pyridyl)-21H,23H-porphine iron(III) chloride (FeTPyPCl) on the basal plane of highly oriented pyrolytic graphite (HOPG), and cathodic oxygen reduction was investigated on the surface in 0.1 M HClO 4 . The catalytic activity for oxygen reduction was enhanced by loading transition metal ions (Co 2+ , Ni 2+ , Cu 2+ ) together with FeTPyPCl. The X-ray photoelectron spectrum of the surface suggested that the metal was coordinated by the pyridine-N. The enhancement effect of the transition metals was supported by two different measurements: oxygen reduction at HOPG in 0.1 M HClO 4 dissolving FeTPyPCl and the metal ions; oxygen reduction in 0.1 M HClO 4 at the subsequently well-rinsed and dried HOPG. The ultraviolet–visible spectrum for the solution also suggested the coordination between the pyridyl-N and the metal ions. The oxygen reduction enhancement was attributed to the electronic interaction between the additional transition metal and the Fe center of the porphyrin through the coordination bonds. These results implied that the improvement of the activity of the noble-metal-free catalyst would be possible by the proper introduction of the transition metal ions around the active site.

  12. Reduced graphene oxide and porphyrin. An interactive affair in 2-D.

    Science.gov (United States)

    Wojcik, Aleksandra; Kamat, Prashant V

    2010-11-23

    Photoexcited cationic 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP) undergoes charge-transfer interaction with chemically reduced graphene oxide (RGO). Formation of the ground-state TMPyP-RGO complex in solution is marked by the red-shift of the porphyrin absorption band. This complexation was analyzed by Benesi-Hildebrand plot. Porphyrin fluorescence lifetime reduced from 5 to 1 ns upon complexation with RGO, indicating excited-state interaction between singlet excited porphyrin and RGO. Femtosecond transient absorption measurements carried out with TMPyP adsorbed on RGO film revealed fast decay of the singlet excited state, followed by the formation of a longer-living product with an absorption maximum around 515 nm indicating the formation of a porphyrin radical cation. The ability of TMPyP-RGO to undergo photoinduced charge separation was further confirmed from the photoelectrochemical measurements. TMPyP-RGO coated conducting glass electrodes are capable of generating photocurrent under visible excitation. These results are indicative of the electron transfer between photoexcited porphyrin and RGO. The role of graphene in accepting and shuttling electrons in light-harvesting assemblies is discussed.

  13. Real-time porphyrin detection in plaque and caries: a case study

    Science.gov (United States)

    Timoshchuk, Mari-Alina I.; Ridge, Jeremy S.; Rugg, Amanda L.; Nelson, Leonard Y.; Kim, Amy S.; Seibel, Eric J.

    2015-02-01

    An ultrathin scanning fiber endoscope, originally developed for cancer diagnosis, was used in a case study to locate plaque and caries. The imaging system incorporated software mitigation of background auto-fluorescence (AF). In conventional fluorescence imaging, varying AF across a tooth surface can mask low-level porphyrin signals. Laser-induced auto-fluorescence signals of dental tissue excited using a 405-nm laser typically produce fluorescence over a wavelength range extending from 440-nm to 750-nm. Anaerobic bacterial metabolism produces various porphyrin species (eg. protoporphyrin IX) that are located in carious enamel, dentin, gingivitis sites, and plaque. In our case study, these porphyrin deposits remained as long as one day after prophylaxis. Imaging the tooth surface using 405-nm excitation and subtracting the natural AF enhances the image contrast of low-level porphyrin deposits, which would otherwise be masked by the high background AF. In a case study, healthy tissues as well as sites of early and advanced caries formations were scanned for visual and quantitative signs of red fluorescence associated with porphyrin species using a background mitigation algorithm. Initial findings show increasing amplitudes of red fluorescence as caries severity increases from early to late stages. Sites of plaque accumulation also displayed red fluorescence similar to that found in carious dental tissue. The use of real-time background mitigation of natural dental AF can enhance the detection of low porphyrin concentrations that are indicators of early stage caries formation.

  14. Photoluminescence and dynamics of excitation relaxation in graphene oxide-porphyrin nanorods composite

    International Nuclear Information System (INIS)

    Khenfouch, M.; Wéry, J.; Baïtoul, M.; Maaza, M.

    2014-01-01

    Generally, porphyrin nanostructured materials are known by playing many roles such as photoconductors, photovoltaics and capable of light induced charging. Also their combination with acceptors like graphene, the rising two dimension material, added exciting physical and chemical properties. In this work, Morphology, optical absorption and photoluminescence properties were investigated in order to elucidate the interaction between the few layered graphene oxide (FGO) and pophyrin nanorods. Reporting on the photoluminescence (PL) of both porphyrin nanorods and FGO/porphyrin nanorods composite, synthesized via a self-assembly method, we have experimentally demonstrated the generation of a new photoluminescence band giving rise to a white light. This luminescence was studied by the analysis of its origins and dynamics which show a huge change of exciton life time found to be longer after the interaction with graphene oxide (GO) sheets. -- Highlights: • We prepared FGO-porphyrin nanorods composite via a simple chemical method. • Luminescence properties were studied presenting the absorption, photoluminescence and dynamics measurements. • These results show the emission of a white light which we studied its emissions origins. • TEM images show FGO sheets decorated with porphyrin nanorods. • FGO had like effect an increase of the exciton lifetime in porphyrin nanorods

  15. Uncharged water-soluble porphyrin tweezers as a supramolecular sensor for α-amino acids

    International Nuclear Information System (INIS)

    Villari, Valentina; Mineo, Placido; Micali, Norberto; Angelini, Nicola; Vitalini, Daniele; Scamporrino, Emilio

    2007-01-01

    The binding between uncharged cobalt porphyrin tweezers and L-amino acids in aqueous solutions is studied by means of UV-vis and circular dichroism spectroscopy. By varying the length of the aliphatic bridge between the two porphyrin units, the number of cobalt ions in the porphyrin cores and the pH of the solution, the chirality induction phenomenon has been investigated. The binding of the amino acid to the porphyrin seems to occur via a coordination mechanism between the metal and the nitrogen of the amino group; the steric, hydrophobic and π-π interactions operate to stabilize the complexes. The chirogenesis displays an opposite behaviour in the presence of aromatic guests with respect to the non-aromatic ones. Moreover, the UV-vis and the induced circular dichroism spectral changes suggest that the amino acid arrangement in the tweezers is determined by many factors, so that, unlike in organic solvent, the porphyrin tweezers in aqueous solution allow for two different arrangements of the same aromatic amino acid. The experimental findings indicate that the porphyrins tweezers reported in the paper are promising in opening perspectives toward their application as a selective molecular sensor in aqueous solutions directly

  16. Fluorescence quenching behaviour of uric acid interacting with water-soluble cationic porphyrin

    International Nuclear Information System (INIS)

    Makarska-Bialokoz, Magdalena; Borowski, Piotr

    2015-01-01

    The process of association between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H 2 TTMePP) and uric acid as well as its sodium salt has been studied in aqueous NaOH solution analysing its absorption and steady-state fluorescence spectra. The fluorescence quenching effect observed during interactions porphyrin-uric acid compounds points at the fractional accessibility of the fluorophore for the quencher. The association and fluorescence quenching constants are of the order of magnitude of 10 5 mol −1 . The fluorescence lifetimes and the quantum yields of the porphyrin anionic form were established. The results demonstrate that uric acid and its sodium salt can interact with H 2 TTMePP at basic pH and through formation of stacking complexes are able to quench its ability to emission. - Highlights: • Association study of water soluble cationic porphyrin with uric acid. • Porphyrin absorption spectra undergo the bathochromic and hypochromic effects. • Uric acid interacts with porphyrin in inhibiting manner, quenching its emission. • Fluorescence quenching effect testifies for the partial inactivation of a porphyrin. • The association and fluorescence quenching constants were calculated

  17. Fluorescence quenching behaviour of uric acid interacting with water-soluble cationic porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Makarska-Bialokoz, Magdalena, E-mail: makarska@hektor.umcs.lublin.pl [Department of Inorganic Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 2, 20-031 Lublin (Poland); Borowski, Piotr [Faculty of Chemistry, Maria Curie-Sklodowska University M. C. Sklodowska Sq. 3, 20-031 Lublin (Poland)

    2015-04-15

    The process of association between 5,10,15,20-tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine tetra-p-tosylate (H{sub 2}TTMePP) and uric acid as well as its sodium salt has been studied in aqueous NaOH solution analysing its absorption and steady-state fluorescence spectra. The fluorescence quenching effect observed during interactions porphyrin-uric acid compounds points at the fractional accessibility of the fluorophore for the quencher. The association and fluorescence quenching constants are of the order of magnitude of 10{sup 5} mol{sup −1}. The fluorescence lifetimes and the quantum yields of the porphyrin anionic form were established. The results demonstrate that uric acid and its sodium salt can interact with H{sub 2}TTMePP at basic pH and through formation of stacking complexes are able to quench its ability to emission. - Highlights: • Association study of water soluble cationic porphyrin with uric acid. • Porphyrin absorption spectra undergo the bathochromic and hypochromic effects. • Uric acid interacts with porphyrin in inhibiting manner, quenching its emission. • Fluorescence quenching effect testifies for the partial inactivation of a porphyrin. • The association and fluorescence quenching constants were calculated.

  18. Dehalogenation of chloroalkanes by nickel(i) porphyrin derivatives, a computational study.

    Science.gov (United States)

    Szatkowski, L; Hall, M B

    2016-11-14

    The nickel(i) octaethylisobacteriochlorin anion ([OEiBCh-Ni (I) ] - ) is commonly used as a synthetic model of cofactor F 430 from Methyl-Coenzyme M Reductase. In this regard, experimental studies show that [OEiBCh-Ni (I) ] - can catalyze dehalogenation of aliphatic halides in DMF solution by a highly efficient S N 2 reaction. To better understand this process, we constructed theoretical models of the dehalogenation of chloromethane by a simple nickel(i) isobacteriochlorin anion and compared its reactivity with that of similar Ni (I) complexes with other porphyrin-derived ligands: porphyrin, chlorin, bactreriochlorin, hexahydroporphyrin and octahydroporphyrin. Our calculations predict that all of the porphyrin derivative's model reactions proceed through low-spin complexes. Relative to the energy of the separate reactants the theoretical activation energies (free-energy barriers with solvation corrections) for the dehalogenation of chloromethane are similar for all of the porphyrin derivatives and range for the different functionals from 10-15 kcal mol -1 for B3LYP to 5-10 kcal mol -1 for M06-L and to 13-18 kcal mol -1 for ωB97X-D. The relative free energies of the products of the dehalogenation step, L-Ni-Me adducts, have a range from -5 to -40 kcal mol -1 for all functionals; generally becoming more negative with increasing saturation of the porphyrin ligand. Moreover, no significant differences in the theoretical chlorine kinetic isotope effect were discernable with change of porphyrin ligand.

  19. Structural and Molecular Characterization of meso-Substituted Zinc Porphyrins: A DFT Supported Study

    Directory of Open Access Journals (Sweden)

    Giuseppe Mele

    2011-12-01

    Full Text Available Structural parameters of a range of over 100 meso-substituted zinc porphyrins were reviewed and compared to show how far the nature of the functional group may affect the interatomic distances and bond angles within the porphyrin core. It was proved that even despite evident deformations of the molecular structure, involving twisting of the porphyrin's central plane, the coupled π-bonding system remains flexible and stable. DFT calculations were applied to a number of selected porphyrins representative for the reviewed compounds to emphasize the relevance of theoretical methods in structural investigations of complex macrocyclic molecular systems. Experimental and DFT-simulated IR spectral data were reported and analyzed in context of the individual molecular features introduced by the meso substituents into the porphyrin moiety base. Raw experimental spectral data, including 1H- and 13C-NMR, UV-Vis, FTIR, XRD, and other relevant physicochemical details have been provided for a specially chosen reference zinc porphyrin functionalized by tert-butylphenyl groups.

  20. Photoluminescence and dynamics of excitation relaxation in graphene oxide-porphyrin nanorods composite

    Energy Technology Data Exchange (ETDEWEB)

    Khenfouch, M., E-mail: khenfouch@yahoo.fr [University Sidi Mohamed Ben Abdellah, Faculty of Sciences Dhar el Mahraz, Laboratory of Solid State Physics, Group of Polymers and Nanomaterials, BP 1796 Atlas, Fez 30 000 (Morocco); iThemba LABS-National Research Foundation of South Africa, Old Faure Road, PO Box 722, Somerset West 7129, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Wéry, J. [Institut des Matériaux Jean Rouxel, Nantes, 2 rue de la Houssinière, BP 32229, 44322 Nantes, Cedex 3 (France); Baïtoul, M., E-mail: baitoul@yahoo.fr [University Sidi Mohamed Ben Abdellah, Faculty of Sciences Dhar el Mahraz, Laboratory of Solid State Physics, Group of Polymers and Nanomaterials, BP 1796 Atlas, Fez 30 000 (Morocco); Maaza, M. [iThemba LABS-National Research Foundation of South Africa, Old Faure Road, PO Box 722, Somerset West 7129, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa)

    2014-01-15

    Generally, porphyrin nanostructured materials are known by playing many roles such as photoconductors, photovoltaics and capable of light induced charging. Also their combination with acceptors like graphene, the rising two dimension material, added exciting physical and chemical properties. In this work, Morphology, optical absorption and photoluminescence properties were investigated in order to elucidate the interaction between the few layered graphene oxide (FGO) and pophyrin nanorods. Reporting on the photoluminescence (PL) of both porphyrin nanorods and FGO/porphyrin nanorods composite, synthesized via a self-assembly method, we have experimentally demonstrated the generation of a new photoluminescence band giving rise to a white light. This luminescence was studied by the analysis of its origins and dynamics which show a huge change of exciton life time found to be longer after the interaction with graphene oxide (GO) sheets. -- Highlights: • We prepared FGO-porphyrin nanorods composite via a simple chemical method. • Luminescence properties were studied presenting the absorption, photoluminescence and dynamics measurements. • These results show the emission of a white light which we studied its emissions origins. • TEM images show FGO sheets decorated with porphyrin nanorods. • FGO had like effect an increase of the exciton lifetime in porphyrin nanorods.

  1. π -Plasmon model for carbon nano structures: Application to porphyrin

    International Nuclear Information System (INIS)

    Ha, Dao Thu; Anh, Chu Thuy; Nga, Do Thi; Thanh, Le Minh; Van, Tran Thi Thanh; Viet, Nguyen Ai

    2016-01-01

    In traditional concept, the optical properties of semiconductors and semimetals near their fundamental optical band gaps are attributed to single excitations (such electron-hole pairs, excitons...). In our earlier article, we proposed the collective mechanism of π -plasmons for optical properties of low dimensional carbon nano structures. A simple way to calculate the peak positions of UV-vis absorption spectra was pointed out and gave a good agreement with experimental data. In this work we analyze different schemas to calculate the UV-vis absorption peaks. A new parameter k which characterizes the dependence of schema on geometry and number of carbon sites is defined. As an example, the case of porphyrin was investigated. (paper)

  2. Respiratory Monitoring by Porphyrin Modified Quartz Crystal Microbalance Sensors

    Directory of Open Access Journals (Sweden)

    Seung-Woo Lee

    2011-01-01

    Full Text Available A respiratory monitoring system based on a quartz crystal microbalance (QCM sensor with a functional film was designed and investigated. Porphyrins 5,10,15,20-tetrakis-(4-sulfophenyl-21H,23H-porphine (TSPP and 5,10,15,20-tetrakis-(4-sulfophenyl-21H, 23H-porphine manganese (III chloride (MnTSPP used as sensitive elements were assembled with a poly(diallyldimethyl ammonium chloride (PDDA. Films were deposited on the QCM resonators using layer-by-layer method in order to develop the sensor. The developed system, in which the sensor response reflects lung movements, was able to track human respiration providing respiratory rate (RR and respiratory pattern (RP. The sensor system was tested on healthy volunteers to compare RPs and calculate RRs. The operation principle of the proposed system is based on the fast adsorption/desorption behavior of water originated from human breath into the sensor films deposited on the QCM electrode.

  3. Electron injection dynamics in high-potential porphyrin photoanodes.

    Science.gov (United States)

    Milot, Rebecca L; Schmuttenmaer, Charles A

    2015-05-19

    There is a growing need to utilize carbon neutral energy sources, and it is well known that solar energy can easily satisfy all of humanity's requirements. In order to make solar energy a viable alternative to fossil fuels, the problem of intermittency must be solved. Batteries and supercapacitors are an area of active research, but they currently have relatively low energy-to-mass storage capacity. An alternative and very promising possibility is to store energy in chemical bonds, or make a solar fuel. The process of making solar fuel is not new, since photosynthesis has been occurring on earth for about 3 billion years. In order to produce any fuel, protons and electrons must be harvested from a species in its oxidized form. Photosynthesis uses the only viable source of electrons and protons on the scale needed for global energy demands: water. Because artificial photosynthesis is a lofty goal, water oxidation, which is a crucial step in the process, has been the initial focus. This Account provides an overview of how terahertz spectroscopy is used to study electron injection, highlights trends from previously published reports, and concludes with a future outlook. It begins by exploring similarities and differences between dye-sensitized solar cells (DSSCs) for producing electricity and a putative device for splitting water and producing a solar fuel. It then identifies two important problems encountered when adapting DSSC technology to water oxidation-improper energy matching between sensitizer energy levels with the potential for water oxidation and the instability of common anchoring groups in water-and discusses steps to address them. Emphasis is placed on electron injection from sensitizers to metal oxides because this process is the initial step in charge transport. Both the rate and efficiency of electron injection are analyzed on a sub-picosecond time scale using time-resolved terahertz spectroscopy (TRTS). Bio-inspired pentafluorophenyl porphyrins are

  4. Thermal decomposition of vinyl- and allylsilane platinum(II ...

    African Journals Online (AJOL)

    CHCH2SiMe3)], K[(acac)PtCl(CH2=CHSiMe3)] and [PtCl(CH2=CHCH2SiMe3)]2, were examined. All complexes were found to be stable at room temperature but they decomposed without melting above about 90 oC. The allylsilane complex ...

  5. Reactions of neopentane and neohexane on platinum/Y-zeolite and platinum/silica catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Foger, K.; Anderson, J.R.

    1978-10-13

    The hydrocracking/hydroisomerization reaction of 20:1 hydrogen/neopentane at 455-625/sup 0/K was studied on platinum-exchanged sodium, calcium, and lanthanum Y zeolites and Aerosil-supported platinum of 1-20 nm average platinum particle size, by analysis of the product distribution, ESCA, and temperature-programed desorption. The results suggested that the reaction occurs only on platinum and that it proceeds by two parallel pathways which have different activation energies and whose relative proportion depends on the particle size. One pathway is the conventionally accepted one on low-index crystallite facets; the other proceeds on single-surface platinum atoms of low coordination (corner or edge atoms) which become more abundant at lower crystallite size. In both cases, the adsorbed intermediate may undergo either isomerization or hydrogenolysis; the selectivity depends on the hydrogen partial pressure and the relative strength of adsorption of hydrogen and neopentane. Neohexane isomerization selectivity on the same catalysts is consistent with a carbonium ion mechanism on a dual-function catalyst.

  6. Electrochemical behavior of titanium implanted with platinum

    International Nuclear Information System (INIS)

    Thompson, N.G.; Lichter, B.D.; Appleton, B.R.; Kelly, E.J.; White, C.W.

    1979-01-01

    The following conclusions apply to Ti(Pt) near-surface alloys studied. (1) Open-circuit corrosion measurements show that accumulation of platinum may occur at a surface concentration of 0.32 atomic percent Pt while no accumulation occurs at 0.16 atomic percent Pt. However, these results do not allow a distinction as to cause of accumulation to be made between concentration effects and effects due to the presence of an oxide film. (2) Potentiostatic corrosion at -0.450 V (active corrosion) establish that little or no accumulation of platinum occurs at an oxide-free surface for concentrations less than 0.086 atomic percent Pt; whereas, a large amount of accumulation occurs for a distribution with a peak concentration of 0.83 atomic percent Pt. (3) An initial distribution having a peak concentration of 0.32 atomic percent platinum is sufficient to induce natural passivity in titanium and bring a freely corroding sample to a potential of 0.269 V. This is nearly the applicable reversible potential (-0.260 V) for the hydrogen reaction in 1N H 2 SO 4 . (4) Of three samples which showed accumulation, platinum was eventually lost for two of these samples (0.32 atomic percent, open-circuit corrosion; 0.83 atomic percent, potentiostatic corrosion). The remaining sample (9.1 atomic percent, open-circuit corrosion) maintained the maximum possible potential of -0.260 V for the length of the experiment (approx. 30 days). (5) For samples which had been polarized at -0.300 to -0.340 V and which had eventually reverted to the behavior of pure Ti, post corrosion RBS measurements reveal that a substantial fraction of the Pt fluence is retained on the surface in an electrochemically inactive state

  7. Synthesis and self-organization of zinc β-(dialkoxyphosphoryl)porphyrins in the solid state and in solution.

    Science.gov (United States)

    Vinogradova, Ekaterina V; Enakieva, Yulia Y; Nefedov, Sergey E; Birin, Kirill P; Tsivadze, Aslan Y; Gorbunova, Yulia G; Bessmertnykh Lemeune, Alla G; Stern, Christine; Guilard, Roger

    2012-11-19

    The first synthesis and self-organization of zinc β-phosphorylporphyrins in the solid state and in solution are reported. β-Dialkoxyphosphoryl-5,10,15,20-tetraphenylporphyrins and their Zn(II) complexes have been synthesized in good yields by using Pd- and Cu-mediated carbon-phosphorous bond-forming reactions. The Cu-mediated reaction allowed to prepare the mono-β-(dialkoxyphosphoryl)porphyrins 1 Zn-3 Zn starting from the β-bromo-substituted zinc porphyrinate ZnTPPBr (TPP = tetraphenylporphyrin) and dialkyl phosphites HP(O)(OR)(2) (R = Et, iPr, nBu). The derivatives 1 Zn-3 Zn were obtained in good yields by using one to three equivalents of CuI. When the reaction was carried out in the presence of catalytic amounts of palladium complexes in toluene, the desired zinc derivative 1 Zn was obtained in up to 72% yield. The use of a Pd-catalyzed C-P bond-forming reaction was further extended to the synthesis of β-poly(dialkoxyphosphoryl)porphyrins. An unprecedented one-pot sequence involving consecutive reduction and phosphorylation of H(2)TPPBr(4) led to the formation of a mixture of the 2,12- and 2,13-bis(dialkoxy)phosphorylporphyrins 5 H(2) and 6 H(2) in 81% total yield. According to the X-ray diffraction studies, 1 Zn and 3 Zn are partially overlapped cofacial dimers formed through the coordination of two Zn centers by two phosphoryl groups belonging to the adjacent molecules. The equilibrium between the monomeric and the dimeric species exists in solutions of 1 Zn and 3 Zn in weakly polar solvents according to spectroscopic data (UV/Vis absorption and NMR spectroscopy). The ratio of each form is dependent on the concentration, temperature, and traces of water or methanol. These features demonstrated that zinc β-phosphorylporphyrins can be regarded as new model compounds for the weakly coupled chlorophyll pair in the photosynthesis process. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Metal-porphyrin interactions. V. Kinetics of cyanide addition to a water soluble iron porphyrin dimer(1)

    Energy Technology Data Exchange (ETDEWEB)

    Hambright, P; Rishnamurthy, M K

    1975-01-01

    The kinetics of cyanide addition to the water-soluble oxybridged iron dimer of tetra (p-sulophenyl) porphin indicate that HCN is the reactant. The rate law is of the form: Rate = (3.8 +- 0.2) x 10/sup 4/ (Fe dimer) (HCN)/(1 + (3.1 +- 0.3) x 10/sup 10/ (H/sup +/)) at 25/sup 0/ ..mu.. = 0.7 (NaNO/sub 3/). The cyano iron dimer dissociates into dicyano iron monomers by two pathways, one first order in (H/sup +/), and one proportional to (H/sup +/)(CN/sup -/)/sup 2/. The mechanism of this dimer reaction is compared to iron porphyrin monomer systems.

  9. On the enzymatic formation of platinum nanoparticles

    International Nuclear Information System (INIS)

    Govender, Y.; Riddin, T. L.; Gericke, M.; Whiteley, C. G.

    2010-01-01

    A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 o C, respectively, a half-life stability of 36 min and a V max and K m of 3.57 nmol min -1 mL -1 and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H 2 PtCl 6 ) at 1 or 2 mM with a K i value of 118 μM. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 o C) afforded o C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

  10. Platinum boride nanowires: Synthesis and characterization

    International Nuclear Information System (INIS)

    Ding Zhanhui; Qiu Lixia; Zhang Jian; Yao Bin; Cui Tian; Guan Weiming; Zheng Weitao; Wang Wenquan; Zhao Xudong; Liu Xiaoyang

    2012-01-01

    Highlights: ► Platinum boride nanowires have been synthesized via the direct current arc discharge method. ► XRD, TEM and SAED indicate that the nanowires are single-crystal PtB. ► Two broad photoluminescence emission peaks at about 586 nm and 626 nm have been observed in the PL spectroscopy of PtB nanowires. - Abstract: Platinum boride (PtB) nanowires have been successfully fabricated with direct current arc discharge method using a milled mixture of platinum (Pt) and boron nitride (BN) powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the compositions, morphology, and structures of the samples. The results show that PtB nanowires are 30–50 nm thick and 20–30 μm long. TEM and selected area electron diffraction (SAED) patterns identify that the PtB nanowires are single-crystalline in nature. A growth mechanism based on vapor–liquid–solid (VLS) process is proposed for the formation of nanowires.

  11. Photodynamic inactivation of Candida albicans sensitized by tri- and tetra-cationic porphyrin derivatives.

    Science.gov (United States)

    Cormick, M Paula; Alvarez, M Gabriela; Rovera, Marisa; Durantini, Edgardo N

    2009-04-01

    The photodynamic action of 5-(4-trifluorophenyl)-10,15,20-tris(4-trimethylammoniumphenyl)porphyrin iodide (TFAP(3+)) and 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin p-tosylate (TMAP(4+)) has been studied in vitro on Candida albicans. The results of these cationic porphyrins were compared with those of 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS(4-)), which characterizes an anionic sensitizer. In vitro investigations show that these cationic porphyrins are rapidly bound to C. albicans cells, reaching a value of approximately 1.4 nmol/10(6) cells, when the cellular suspensions were incubated with 5 microM sensitizer for 30 min. In contrast, TPPS(4-) is poorly uptaken by yeast cells. The fluorescence spectra of these sensitizers into the cells confirm this behaviour. The amount of porphyrin binds to cells is dependent on both sensitizer concentrations (1-5 microM) and cells densities (10(6)-10(8) cells/mL). Photosensitized inactivation of C. albicans cellular suspensions increases with sensitizer concentration, causing a approximately 5 log decrease of cell survival, when the cultures are treated with 5 microM of cationic porphyrin and irradiated for 30 min. However, the photocytotoxicity decreases with an increase in the cell density, according to its low binding to cells. Under these conditions, the photodynamic activity of TFAP(3+) is quite similar to that produced by TMAP(4+), whereas no important inactivation effect was found for TPPS(4)(-). The high photodynamic activity of cationic porphyrins was confirmed by growth delay experiments. Thus, C. albicans cell growth was not detected in the presence of 5 microM TFAP(3+). Photodynamic inactivation capacities of these sensitizers were also evaluated on C. albicans cells growing in colonies on agar surfaces. Cationic porphyrins produce a growth delay of C. albicans colonies and viability of cells was not observed after 3 h irradiation, indicating a complete inactivation of yeast cells

  12. A new method for evaluating the conformations and normal modes of macromolecule vibrations with a reduced force field. 2. Application to nonplanar distorted metal porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Unger, E.; Beck, M.; Lipski, R.J.; Dreybrodt, W.; Medforth, C.J.; Smith, K.M.; Schweitzer-Stenner, R.

    1999-11-11

    The authors have developed a novel method for molecular mechanics calculations and normal-mode analysis. It is based on symmetry of local units that constitutes the given molecule. Compared with general valence force field calculations, the number of free parameters is reduced by 40--80% in the procedure. It was found to reproduce very well the vibrational frequencies and mode compositions of aromatic compounds and porphyrins, as shown by comparison with DFT calculations. A slightly altered force field obtained from Ni(II) porphin was then used to calculate the structure and the normal modes of several meso-substituted Ni(II) porphyrins which are known to be subject to significant ruffling and/or saddling distortions. This method satisfactorily reproduces their nonplanar structure and Raman band frequencies in the natural abundance and isotopic derivative spectra. The polarization properties of bands from out-of-plane modes are in accordance with the predicted nonplanar distortions. Moreover, some of the modes below 800 cm{sup {minus}1} which appear intense in the Raman spectra contain considerable contributions from both in-plane and out-of-plane vibrations, so that the conventional mode assignments become questionable. The authors also demonstrate that the intensity and polarization of some low-frequency Raman bands can be used as a (quantitative) marker to elucidate type and magnitude of out-of-plane distortions. These were recently shown to affect heme groups of hemoglobin, myoglobin, and, in particular, of cytochrome c.

  13. Recovery of Platinum from Dilute Chloride Media Using Biosorbents

    Science.gov (United States)

    Zeytuncu, B.; Morcali, M. H.; Yucel, O.

    Pistachio nut shells and Rice husk, a biomass residue, were investigated as adsorbents for the platinum uptake from synthetically prepared dilute chloroplatinic acid solutions. The effects of the different uptake parameters on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell material was activated, platinum uptake (%) was poor compared with rice husk. However, after the pistachio nut shell material was activated at 1000°C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (inactivated and activated) and rice husk were characterized by Attenuated Total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR).

  14. Strategies for the fabrication of porous platinum electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Kloke, Arne; Stetten, Felix von; Kerzenmacher, Sven [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); Zengerle, Roland [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg (Germany)

    2011-11-16

    Porous platinum is of high technological importance due to its various applications in fuel cells, sensors, stimulation electrodes, mechanical actuators and catalysis in general. Based on a discussion of the general principles behind the reduction of platinum salts and corresponding deposition processes this article discusses techniques available for platinum electrode fabrication. The numerous, different strategies available to fabricate platinum electrodes are reviewed and discussed in the context of their tuning parameters, strengths and weaknesses. These strategies comprise bottom-up approaches as well as top-down approaches. In bottom-up approaches nanoparticles are synthesized in a first step by chemical, photochemical or sonochemical means followed by an electrode formation step by e.g. thin film technology or network formation to create a contiguous and conducting solid electrode structure. In top-down approaches fabrication starts with an already conductive electrode substrate. Corresponding strategies enable the fabrication of substrate-based electrodes by e.g. electrodeposition or the fabrication of self-supporting electrodes by dealloying. As a further top-down strategy, this review describes methods to decorate porous metals other than platinum with a surface layer of platinum. This way, fabrication methods not performable with platinum can be applied to the fabrication of platinum electrodes with the special benefit of low platinum consumption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Oxoferryl-Porphyrin Radical Catalytic Intermediate in Cytochrome bd Oxidases Protects Cells from Formation of Reactive Oxygen Species*

    Science.gov (United States)

    Paulus, Angela; Rossius, Sebastiaan Gijsbertus Hendrik; Dijk, Madelon; de Vries, Simon

    2012-01-01

    The quinol-linked cytochrome bd oxidases are terminal oxidases in respiration. These oxidases harbor a low spin heme b558 that donates electrons to a binuclear heme b595/heme d center. The reaction with O2 and subsequent catalytic steps of the Escherichia coli cytochrome bd-I oxidase were investigated by means of ultra-fast freeze-quench trapping followed by EPR and UV-visible spectroscopy. After the initial binding of O2, the O–O bond is heterolytically cleaved to yield a kinetically competent heme d oxoferryl porphyrin π-cation radical intermediate (compound I) magnetically interacting with heme b595. Compound I accumulates to 0.75–0.85 per enzyme in agreement with its much higher rate of formation (∼20,000 s−1) compared with its rate of decay (∼1,900 s−1). Compound I is next converted to a short lived heme d oxoferryl intermediate (compound II) in a phase kinetically matched to the oxidation of heme b558 before completion of the reaction. The results indicate that cytochrome bd oxidases like the heme-copper oxidases break the O–O bond in a single four-electron transfer without a peroxide intermediate. However, in cytochrome bd oxidases, the fourth electron is donated by the porphyrin moiety rather than by a nearby amino acid. The production of reactive oxygen species by the cytochrome bd oxidase was below the detection level of 1 per 1000 turnovers. We propose that the two classes of terminal oxidases have mechanistically converged to enzymes in which the O–O bond is broken in a single four-electron transfer reaction to safeguard the cell from the formation of reactive oxygen species. PMID:22287551

  16. Fluorescence spectroscopic studies on substituted porphyrins in homogeneous solvents and cationic micellar medium

    International Nuclear Information System (INIS)

    Phukan, Smritakshi; Mishra, Bhupendra; Chandra Shekar, K.P.; Kumar, Anil; Kumar, Dalip; Mitra, Sivaprasad

    2013-01-01

    Steady state and time-resolved fluorescence properties of porphyrin appended 1,3,4-oxadiazoles and thiazoles were described in homogeneous medium as well as in presence of cationic surfactant cetyltrimethylammonium bromide (CTAB). The electron withdrawing substituent on the porphyrin moiety in both the cases make a donor–spacer–acceptor type of intramolecular photoinduced electron transfer (PET) system resulting substantial quenching in porphyrin fluorescence due to partial energy migration towards the acceptor in the excited state. The increase in fluorescence yield as well as appreciable difference in fluorescence decay behavior in aqueous buffer solution of pH 4.2 from that in chloroform solution is believed due to partial protonation of the porphyrin ring. All the investigated systems show preferential binding into the interfacial region of the micellar sub-domain with varying degree of penetration depending on the nature of the substituent. Almost 2–4 fold increase in fluorescence yield for the probes is explained on the basis of restricted flexibility and corresponding decrease in total nonradiative rate inside the micellar interface layer. - Highlights: ► Synthesis and detail fluorescence studies of a series of porphyrin appended 1,3,4-oxadiazoles and thiazoles. ► Comparison of homogeneous solvent study with that in CTAB. ► Substantial porphyrin fluorescence quenching in donor–spacer–acceptor type system. ► Preferential binding of the substituted porphyrins in micellar sub-domain. ► Appreciable increase in fluorescence yield in micellar interface layer is due to decrease in total nonradiative rate.

  17. An educational overview of the chemistry, biochemistry and therapeutic aspects of Mn porphyrins--From superoxide dismutation to H2O2-driven pathways.

    Science.gov (United States)

    Batinic-Haberle, Ines; Tovmasyan, Artak; Spasojevic, Ivan

    2015-08-01

    Most of the SOD mimics thus far developed belong to the classes of Mn-(MnPs) and Fe porphyrins(FePs), Mn(III) salens, Mn(II) cyclic polyamines and metal salts. Due to their remarkable stability we have predominantly explored Mn porphyrins, aiming initially at mimicking kinetics and thermodynamics of the catalysis of O2(-) dismutation by SOD enzymes. Several MnPs are of potency similar to SOD enzymes. The in vivo bioavailability and toxicity of MnPs have been addressed also. Numerous in vitro and in vivo studies indicate their impressive therapeutic efficacy. Increasing insight into complex cellular redox biology has been accompanied by increasing awareness of complex redox chemistry of MnPs. During O2(-) dismutation process, the most powerful Mn porphyrin-based SOD mimics reduce and oxidize O2(-) with close to identical rate constants. MnPs reduce and oxidize other reactive species also (none of them specific to MnPs), acting as reductants (antioxidant) and pro-oxidants. Distinction must be made between the type of reactions of MnPs and the favorable therapeutic effects we observe; the latter may be of either anti- or pro-oxidative nature. H2O2/MnP mediated oxidation of protein thiols and its impact on cellular transcription seems to dominate redox biology of MnPs. It has been thus far demonstrated that the ability of MnPs to catalyze O2(-) dismutation parallels all other reactivities (such as ONOO(-) reduction) and in turn their therapeutic efficacies. Assuming that all diseases have in common the perturbation of cellular redox environment, developing SOD mimics still seems to be the appropriate strategy for the design of potent redox-active therapeutics. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  18. REGIOSELECTIVE OXIDATIONS OF EQUILENIN DERIVATIVES CATALYZED BY A RHODIUM (III) PORPHYRIN COMPLEX-CONTRAST WITH THE MANGANESE (III) PORPHYRIN. (R826653)

    Science.gov (United States)

    AbstractEquilenin acetate and dihydroequilenin acetate were oxidized with iodosobenzene and a rhodium(III) porphyrin catalyst. The selectivity of the reactions differs from that with the corresponding Mn(III) catalyst, or from that of free radical chain oxidation.

  19. Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

    Science.gov (United States)

    Zhong, Qiwen

    photosynthesis. Photosynthesis uses light from the sun to drive a series of chemical reactions. Most natural photosynthetic systems utilize chlorophylls to absorb light energy and carry out photochemical charge separation that stores energy in the form of chemical bonds. The sun produces a broad spectrum of light output that ranges from gamma rays to radio waves. The entire visible range of light (400-700 nm) and some wavelengths in the NIR (700-1000 nm), are highly active in driving photosynthesis. Although the most familiar chlorophyll-containing organisms, such as plants, algae and cyanobacteria, cannot use light longer than 700 nm, anoxygenic bacterium containing bacteriochlorophylls can use the NIR part of the solar spectrum. No organism is known to utilize light of wavelength longer than about 1000 nm for photosynthesis. NIR light has a very low-energy content in each photon, so that large numbers of these low-energy photons would have to be used to drive the chemical reactions of photosynthesis. This is thermodynamically possible but would require a fundamentally different molecular mechanism that is more akin to a heat engine than to photochemistry. Early work on developing light absorbing materials for OPVs was inspired by photosynthesis in which light is absorbed by chlorophyll. Structurally related to chlorophyll is the porphyrin family, which has accordingly drawn much interest as the potential light absorbing component in OPV applications. In this dissertation, the design and detail studies of several porphyrin-based NIR absorbing materials, including pi--extended perylenyl porphryins and pyrazole-containing carbaporphyrins, as well as porphyrin modified single-walled carbon nanotube hybrids, will be presented, dedicating efforts to develop novel and application-oriented materials for efficient utilization of sustainable solar energy.

  20. Reaction pathways for reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes

    International Nuclear Information System (INIS)

    Cunha, M.C.P.M. da; De Souza, J.P.I.; Nart, F.C.

    2000-01-01

    The reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes has been investigated using differential electrochemical mass spectrometry and in situ FTIR measurements. For 3 M HNO 3 concentration it has been found that nitrate starts the reduction with partial N-O bond dissociation and N-N bond formation generating NO and N 2 O. At potentials lower than 0.2 V the reaction proceeds forming dissolved NH 4 + . For potentials lower than 0 V the reduction continues via a multiple pathway reaction leading to the nonselective production of N 2 , NH 2 OH, and N 2 H 2 . On the alloyed electrodes, the production of NO and N 2 O has been observed in both cathodic and anodic scans, while on pure platinum and rhodium electrodes the reaction has been observed only during the cathodic scan. Contrasting with the pure platinum and rhodium alloys, where the N-O bond break starts forming NO and N 2 O, on the alloys HNO 2 has been observed as the first reaction step. For alloys with higher rhodium composition, like Pt 75 Rh 25 , no N 2 has been detected for potentials lower than 0 V

  1. Long term survival with whole abdominopelvic irradiation (WAI) in platinum-refractory ovarian cancer

    International Nuclear Information System (INIS)

    Cmelak, Anthony J.; Cox, Richard S.; Kapp, Daniel S.

    1996-01-01

    Purpose: To evaluate the efficacy and toxicity of WAI in persistent or recurrent epithelial ovarian carcinoma after initial chemotherapy. Methods and Materials: Between 1970 and 1995, 41 women with persistent or recurrent ovarian carcinoma after initial surgical debulking and chemotherapy were treated with WAI. Median age was 57 years (range 27-75). Initial FIGO stages were I and II - 5 patients (12%), III - 26 (64%), and IV - 10 (24%). Tumor grade was 1 - 4 (10%), II - 16 (39%), and III - 20 (49%). Four to eighteen (median eight) cycles of chemotherapy had been given prior to WAI. Thirty-one patients had received platinum-based regimens, and 22 of these had failed within six months after completion of chemotherapy (platinum-refractory). Prior to WAI, 11 (27%) patients had microscopic residual disease, 21 (51%) had gross residual disease up to 1.5 cm, and 9 (22%) had tumors greater than 1.5 cm in maximal diameter. Median doses of 28 Gy to the abdomen and 48 Gy to the pelvis were delivered using an open-field technique with appropriate liver and kidney shielding. Results: With follow-up of 1 month to 16.5 years, the 5-year actuarial disease specific survival was 47% in all 41 patients, and 49% in 22 platinum-refractory patients. Both disease bulk at WAI (p -4 ) and initial stage (p=0.005) were of prognostic value. Five-year disease specific survivals were stage I and II - 100%, stage III - 55%, and stage IV - 27%. Five-year disease specific survival of all nonbulky (less than 1.5 cm) patients was 40%; 0% for patients with disease greater than 1.5 cm. Five-year disease specific survival for grade I - 66%, II - 59%, and III - 33%. Stage I, II, or III patients with residual disease bulk of 1.5 cm or less before WAI had a 10-year actuarial disease specific survival of 50%. Twelve patients (29%) failed to complete the planned course of WAI due to acute toxicity (most often due to prolonged thrombocytopenia). Late bowel toxicity included obstruction in one patient and

  2. Synthesis and characterization of a novel series of meso (nitrophenyl and meso (carboxyphenyl substituted porphyrins

    Directory of Open Access Journals (Sweden)

    Schiavon Marco A.

    2000-01-01

    Full Text Available The anionic 5,10,15-tris(4-carboxyphenyl, 20-mono(2-nitrophenyl porphyrin (1, 5,10(or 15-bis(4-carboxyphenyl, 15(or 10,20-bis(2-nitrophenylporphyrin (2 and 5-mono(4-carboxyphenyl, 10,15,20-tris(2-nitrophenylporphyrin (3 were sinthesized directly by reaction of pyrrole with substituted benzaldehydes in nitrobenzene/propionic acid media. The benzaldehydes molar ratio was controlled to optimize the synthesis and purification of the desired porphyrins. This new series of porphyrins was characterised by TLC, mass spectrometry (FAB MS, ¹H NMR, UV/Vis, IR and electrochemistry. 5,10,15,20-Tetrakis(4-carboxyphenylporphyrin (4 and 5,10,15,20-Tetrakis(2-nitrophenylporphyrin (5 were also characterised for comparative purposes, completing the series The electrochemical reduction was investigated for the free base and corresponding iron(III porphyrins on glassy carbon and mercury electrodes. The reduction potentials showed the expected dependence on the number of electron-withdrawing nitro groups present on the porphyrin ring providing additional evidences for the characterisation of the synthesised compounds.

  3. A panchromatic anthracene-fused porphyrin sensitizer for dye-sensitized solar cells

    KAUST Repository

    Ball, James M.

    2012-01-01

    The development of ruthenium-free sensitizers which absorb light over a broad range of the solar spectrum is important for improving the power conversion efficiency of dye-sensitized solar cells. Here we study three chemically tailored porphyrin-based dyes. We show that by fusing the porphyrin core to an anthracene unit, we can extend the conjugation length and lower the optical gap, shifting the absorption spectrum into the near-infrared (NIR). All three dyes were tested in dye-sensitized solar cells, using both titanium dioxide and tin dioxide as the electron-transport material. Solar cells incorporating the anthracene-fused porphyrin dye exhibit photocurrent collection at wavelengths up to about 1100 nm, which is the longest reported for a porphyrin-based system. Despite extending the photon absorption bandwidth, device efficiency is found to be low, which is a common property of cells based on porphyrin dyes with NIR absorption. We show that in the present case the efficiency is reduced by inefficient electron injection into the oxide, as opposed to dye regeneration, and highlight some important design considerations for panchromatic sensitizers. © 2012 The Royal Society of Chemistry.

  4. Emission properties of porphyrin compounds in new polymeric PS:CBP host

    Science.gov (United States)

    Jafari, Mohammad Reza; Bahrami, Bahram

    2015-06-01

    In this study, a device with fundamental structure of ITO/PEDOT:PSS (60 nm)/PS:CBP (70 nm)/Al (150 nm) was fabricated. The electroluminescence spectrum of device designated a red shift rather than PS:CBP photoluminescence spectra. It can be suggested that the electroplex emission occurs at PS:CBP interface. By following this step, red light-emitting devices using porphyrin compounds as a red dopant in a new host material PS:CBP with a configuration of ITO/PEDOT:PSS (60 nm)/PS:CBP:porphyrin compounds(70 nm)/Al (150 nm) have been fabricated and investigated. The electroluminescent spectra of the porphyrin compounds were red-shifted as compared with the PS:CBP blend. OLED devices based on doping 3,4PtTPP and TPPNO2 in PS:CBP showed purer red emission compared with ZnTPP and CoTPP doped devices. We believe that the electroluminescence performance of OLED devices based on porphyrin compounds depends on overlaps between the absorption of the porphyrin compounds and the emission of PS:CBP.

  5. Mechanistic aspects of the photodynamic inactivation of Candida albicans induced by cationic porphyrin derivatives.

    Science.gov (United States)

    Quiroga, Ezequiel D; Cormick, M Paula; Pons, Patricia; Alvarez, M Gabriela; Durantini, Edgardo N

    2012-12-01

    Photodynamic inactivation of Candida albicans produced by 5-(4-trifluorophenyl)-10,15,20-tris(4-N,N,N-trimethylammoniumphenyl)porphyrin (TFAP(3+)), 5,10,15,20-tetrakis(4-N,N,N-trimethylammoniumphenyl)porphyrin (TMAP(4+)) and 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin (TMPyP(4+)) was investigated to obtain insight about the mechanism of cellular damage. In solution, absorption spectroscopic studies showed that these cationic porphyrins interact strongly with calf thymus DNA. The electrophoretic analysis indicated that photocleavage of DNA induced by TFAP(3+) took place after long irradiation periods (>5 h). In contrast, TMAP(4+) produced a marked reduction in DNA band after 1 h irradiation. In C. albicans, these cationic porphyrins produced a ∼3.5 log decrease in survival when the cell suspensions (10(7) cells/mL) were incubated with 5 μM photosensitizer and irradiated for 30 min with visible light (fluence 162 J/cm(2)). After this treatment, modifications of genomic DNA isolated from C. albicans cells were not found by electrophoresis. Furthermore, transmission electron microscopy showed structural changes with appearance of low density areas into the cells and irregularities in cell barriers. However, the photodamage to the cell envelope was insufficient to cause the release of intracellular biopolymers. Therefore, modifications in the cytoplasmic biomolecules and alteration in the cell barriers could be mainly involved in C. albicans photoinactivation. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  6. Detection of a weak ring current in a nonaromatic porphyrin nanoring using magnetic circular dichroism.

    Science.gov (United States)

    Kowalska, Patrycja; Peeks, Martin D; Roliński, Tomasz; Anderson, Harry L; Waluk, Jacek

    2017-12-13

    We compare the absorption and magnetic circular dichroism (MCD) spectra of a series of porphyrin oligomers - dimer, tetramer, and hexamer - bound in a linear or cyclic fashion. The MCD signal is extremely weak for low energy transitions in the linear oligomers, but it is amplified when the cyclic porphyrin hexamer binds a template, restricting rotational freedom. The appearance of Faraday A terms in the MCD spectra demonstrates the presence of a magnetic moment, and thus, uncompensated electronic current. The value of the excited state magnetic moment estimated from the A term is very low compared with those of monomeric porphyrins, which confirms the nonaromatic character of the cyclic array and the lack of a global ring current in the ground state of the neutral nanoring. DFT calculations predict the absorption and MCD patterns reasonably well, but fail to reproduce the MCD sign inversion observed in substituted monomeric zinc porphyrins ("soft" chromophores). Interestingly, a correct sign pattern is predicted by INDO/S calculations. Analysis of the MCD spectra of the monomeric porphyrin unit allowed us to distinguish between two close-lying lowest energy transitions, which some previous assignments placed further apart. The present results prove the usefulness of MCD not only for deconvolution and assignment of electronic transitions, but also as a sensitive tool for detecting electronic ring currents.

  7. Syntheses and biological evaluation of F-18 and I-123 labeled porphyrins as potential tumor imaging agents

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. H.; Ji, D. Y. [Inha University, Incheon (Korea, Republic of); Moon, B. S.; Lee, T. S.; Lee, D. H.; Lee, K. C.; Ahn, G. I.; Yang, S. D.; Choi, C. W.; Jun, K. S. [KIRAMS, Seoul (Korea, Republic of)

    2005-07-01

    Photofrin has currently been approved for general use by licensing authorities to treatment for solid tumor and cancer using photodynamic therapy (PDT) that treat to photochemical effect induced by light. Recently, meso-tetra(3-hydroxyphenyl)porphyrin has been developed as one of best tumor localizer and also shown a favorable tissue distribution. We have studied to develop I-123 labeled meso-tetra(3-methoxyphenyl)porphyrins for tumor imaging. We have studied to develop iodine-123 labeled meso-tetra(3-carboxymethoxy phenyl)porphyrin for tumor imaging agent. The radioiodinated porphyrin compound was obtained by the iodination reaction of tin precursor (50 ig) of porphyrin with Na-123I (200 {mu}L, 100-200 mCi), in the presence of peracetic acid (40 {mu}L) in ethanol. Iodine-123 labeled porphyrin derivative was obtained in 20-30% radiochemical yield and purified by HPLC at 2 mL/min using EtOH/water gradient condition and the fraction at 24-26 min was collected and characterized to desired compound by co injection with cold porphyrin analogue. Total time was around 120 min. The in vitro and in vivo of I-123 labeled porphyrin derivative is under studying.

  8. Syntheses and biological evaluation of F-18 and I-123 labeled porphyrins as potential tumor imaging agents

    International Nuclear Information System (INIS)

    Lee, J. H.; Ji, D. Y.; Moon, B. S.; Lee, T. S.; Lee, D. H.; Lee, K. C.; Ahn, G. I.; Yang, S. D.; Choi, C. W.; Jun, K. S.

    2005-01-01

    Photofrin has currently been approved for general use by licensing authorities to treatment for solid tumor and cancer using photodynamic therapy (PDT) that treat to photochemical effect induced by light. Recently, meso-tetra(3-hydroxyphenyl)porphyrin has been developed as one of best tumor localizer and also shown a favorable tissue distribution. We have studied to develop I-123 labeled meso-tetra(3-methoxyphenyl)porphyrins for tumor imaging. We have studied to develop iodine-123 labeled meso-tetra(3-carboxymethoxy phenyl)porphyrin for tumor imaging agent. The radioiodinated porphyrin compound was obtained by the iodination reaction of tin precursor (50 ig) of porphyrin with Na-123I (200 μL, 100-200 mCi), in the presence of peracetic acid (40 μL) in ethanol. Iodine-123 labeled porphyrin derivative was obtained in 20-30% radiochemical yield and purified by HPLC at 2 mL/min using EtOH/water gradient condition and the fraction at 24-26 min was collected and characterized to desired compound by co injection with cold porphyrin analogue. Total time was around 120 min. The in vitro and in vivo of I-123 labeled porphyrin derivative is under studying

  9. Porphyrins from Messel oil shale (Eocene, Germany): Structure elucidation, geochemical and biological significance, and distribution as a function of depth

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo, R.; Bauder, C.; Callot, H.J.; Albrecht, P. (Univ. Louis Pasteur, Strasbourg (France))

    1992-02-01

    The extraction and isolation procedures of twenty nickel porphyrins (seven alkylporphyrins, thirteen carboxylic acids) from lacustrine Messel shale (Eocene, Germany), as well as the unequivocal structural assignments (obtained using 200 and 400 MHz nuclear magnetic resonance (NMR), nuclear Overhauser effect, mass spectrometry, and total or partial synthesis of six reference compounds) are described. Ten porphyrins could be specifically correlated with biological precursors: algal chlorophyll c (4), bacteriochlorophylls d (3), and heme (3), while the remaining ones may arise from several chlorophylls. The structures of these fossil pigments mostly confirm the classical Treibs scheme,' including the origin of some porphyrins from nonchlorophyll sources. They also show that, even in a very immature sediment, deep modifications occur, including, in particular, extensive degradation of chlorophyll E ring. The composition of the porphyrin fractions of Messel oil shale was also studied as a function of depth. A porphyrin acids/alkylporphyrins ratio varying from 0.35 to 24.8 demonstrated that the apparent homogeneity of the shale is not reflected on the molecular scale. This was confirmed when the abundance of the twenty individual porphyrins of known structure was measured along the core. Significant correlations between individual porphyrins were found: fossils of bacteriochlorophylls d, homolog pairs of porphyrins (3-H/3-ethyl), etc.

  10. Porphyrins from Messel oil shale (Eocene, Germany): Structure elucidation, geochemical and biological significance, and distribution as a function of depth

    Science.gov (United States)

    Ocampo, Rubén; Bauder, Claude; Callot, Henry J.; Albrecht, Pierre

    1992-02-01

    The extraction and isolation procedures of twenty nickel porphyrins (seven alkylporphyrins, thirteen carboxylic acids) from lacustrine Messel shale (Eocene, Germany), as well as the unequivocal structural assignments (obtained using 200 and 400 MHz nuclear magnetic resonance (NMR), nuclear Overhauser effect, mass spectrometry and total or partial synthesis of six reference compounds) are described. Ten porphyrins could be specifically correlated with biological precursors: algal chlorophyll c (4), bacteriochlorophylls d (3) and heme (3), while the remaining ones may arise from several chlorophylls. The structures of these fossil pigments mostly confirm the classical "Treibs scheme," including the origin of some porphyrins from nonchlorophyll sources. They also show that, even in a very immature sediment, deep modifications occur, including, in particular, extensive degradation of chlorophyll E ring. The composition of the porphyrin fractions of Messel oil shale was also studied as a function of depth. A porphyrin acids/alkylporphyrins ratio varying from 0.35 to 24.8 demonstrated that the apparent homogeneity of the shale is not reflected on the molecular scale. This was confirmed when the abundance of the twenty individual porphyrins of known structure was measured along the core. Significant correlations between individual porphyrins were found: fossils of bacteriochlorophylls d, homolog pairs of porphyrins (3-H/3-ethyl), etc.

  11. Modeling of Platinum-Aryl Interaction with Amyloid-β Peptide.

    Science.gov (United States)

    Turner, Matthew; Platts, James A; Deeth, Robert J

    2016-03-08

    Ligand field molecular mechanics (LFMM), density functional theory (DFT), and semiempirical PM7 methods are used to study the binding of two Pt(II)-L systems to an N-terminal fragment of the amyloid-β peptide, where L = 2,2-bipyridyl or 1,10-phenanthroline. Molecular dynamics simulations are used to explore the conformational freedom of the peptide using LFMM combined with AMBER molecular mechanics parameters. We establish a modeling protocol, allowing for identification and analysis of favorable platinum-binding modes and peptide conformations. Preferred binding modes are identified for each ligand investigated; metal coordination occurs via Nε in His residues for both ligands--His6ε-His13ε and His6ε-His14ε for the bipyridyl and phenanthroline ligands, respectively. The observed change in binding mode for the different ligands suggests that the binding mode of these platinum-based structures can be controlled by the choice of ligand. In the bipy systems, Boltzmann population at 310 K is dominated by a single conformer, while in the phenanthroline case, three conformations make significant contributions to the ensemble. The relative stability of these conformations is due to the inherent stability of binding platinum via Nε in addition to subtle H-bonding effects.

  12. Bioaccumulation of platinum group metals in dolphins, Stenella sp ...

    African Journals Online (AJOL)

    Platinum group metals (PGMs) concentrations were measured in the tissues= of dolphins (Stenella sp.) caught along the Ghanaian coastline. Tissues from specimens caught by fishermen from Dixcove, western Ghana, were analysed in 2006 for palladium (Pd), platinum (Pt) and rhodium (Rh) using the Neutron Activation ...

  13. Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

    Science.gov (United States)

    Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

    2016-01-26

    Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

  14. Preparation of platinum/iridium scanning probe microscopy tips

    DEFF Research Database (Denmark)

    Sørensen, Alexis Hammer; Hvid, U.; Mortensen, M.W.

    1999-01-01

    oxide layer. In order to explain the relatively high etching rates observed for the otherwise noble metal platinum we suggest that besides anodic corrosion of the platinum by the electrolyte containing chloride ions, a different etching mechanism causes a substantial increase of the etching rate...

  15. Atomically flat platinum films grown on synthetic mica

    Science.gov (United States)

    Tanaka, Hiroyuki; Taniguchi, Masateru

    2018-04-01

    Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

  16. Enzymatic recovery of platinum (IV) from industrial wastewater using ...

    African Journals Online (AJOL)

    highest hydrogen-dependent platinum (IV) reducing activity in the presence of hydrogenase and its physiological electron carrier, cytochrome c3. When the purified hydrogenase enzyme (with and without cytochrome c3) was used with the industrial effluent, containing 7.9 mg.l-1 platinum, only 10 – 15% recovery was noted ...

  17. The effects of thermal-neutron irradiation on platinum and dilute platinum-gold alloys

    International Nuclear Information System (INIS)

    Piani, C.S.B.

    1978-12-01

    The effect of varying defect concentrations on the recovery spectrum of thermal-neutron-irradiated pure platinum after isochronal anneals was investigated. The dose-independence of substages I(A), I(B) and I(C), and the dose dependence of substage I(D) and I(E), were observed to be in agreement with electron-irradiated studies. The 120 K substage in pure platinum was shown not to be due to interstitial-interstitial reactions, but could possibly be accounted for in terms of detrapping of interstitials from impurities or intrinsic immobile defects. The 360 K stage was shown to shift and was suppressed with increasing defect concentration. The possible conversion of the crowdion to a dumbbell near 160 K in Stage ll in platinum, as predicted by the two-interstitial model, was investigated by consideration of the initial slopes of the production curves between 80 K and 300 K. A minimum in these slopes was observed near 160 K and could be interpreted as due to the conversion of the highly mobile crowdion to an immobile dumbbell at this temperature. The influence of varying gold concentrations on the recovery spectrum of platinum was investigated in dilute platinum-gold alloys. The characteristics of several additional substages in Stage ll, due to the gold alloying were comparable to the results of electron-irradiation experiments. The observations made with regard to the impurity (gold) dependence of these substages could be interpreted in terms of the concentrations of the interstitials, vacancies and impurities present in the material. The interpretation of these substages was found to be consistent, if the recovery spectrum was investigated as a function of defect concentration [af

  18. Chiral discrimination in platinum anticancer drugs

    Czech Academy of Sciences Publication Activity Database

    Benedetti, M.; Malina, Jaroslav; Kašpárková, Jana; Brabec, Viktor; Natile, G.

    2002-01-01

    Roč. 110, Suppl. 5 (2002), s. 779-782 ISSN 0091-6765 R&D Projects: GA ČR GA301/00/0556; GA ČR GA305/02/1552; GA AV ČR IAA7004805; GA AV ČR IBS5004107; GA MŠk OC D20.001 Institutional research plan: CEZ:AV0Z5004920 Keywords : DNA * platinum * cancer Subject RIV: BO - Biophysics Impact factor: 3.452, year: 2002

  19. Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D., E-mail: mdvargas@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Quimica; Alves, Wagner A. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Departamento de Quimica; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V. [Universidade Federal do Ceara (UFCE), Fortaleza, CE (Brazil). Centro de Ciencias da Saude. Departamento de Fisiologia e Farmacologia

    2013-04-15

    Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl{sub 2}(OH){sub 2}] 1b-3b(HL = 2-hydroxy-3-[(R{sup 1} -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R{sup 1} = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl{sub 2}] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO{sup -}, i.e., L{sup -}) redox process and irreversible process attributed to the reduction of the Pt{sup 4+}/Pt{sup 2+} pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH{sub 3}){sub 2}Cl{sub 2}(OH){sub 2}]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt{sup 4+}/Pt{sup 2+} reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC{sub 50} values have been observed for 2b-3b, which bear ligands with the largest R{sup 1} groups (HL2-HL3) being the most lipophilic. Furthermore similar IC{sub 50} values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

  20. Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

    International Nuclear Information System (INIS)

    Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D.; Alves, Wagner A.; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V.

    2013-01-01

    Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl 2 (OH) 2 ] 1b-3b(HL = 2-hydroxy-3-[(R 1 -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R 1 = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl 2 ] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO - , i.e., L - ) redox process and irreversible process attributed to the reduction of the Pt 4+ /Pt 2+ pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH 3 ) 2 Cl 2 (OH) 2 ]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt 4+ /Pt 2+ reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC 50 values have been observed for 2b-3b, which bear ligands with the largest R 1 groups (HL2-HL3) being the most lipophilic. Furthermore similar IC 50 values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

  1. An action spectrum for blue and near ultraviolet inactivation of Propionibacterium acnes; with emphasis on a possible porphyrin photosensitization

    International Nuclear Information System (INIS)

    Kjeldstad, B.; Johnsson, A.

    1986-01-01

    Propionibacterium acnes (P. acnes), grown on Eagles medium with different pH, were irradiated with monochromatic light in the range 320 to 440 nm. Different pH leads to different porphyrin concentrations in the cells. The light sensitivity of the bacteria was estimated from the reduction in their ability to form colonies after radiation. The sensitivity was highest for the lowest wavelength (320 nm), and decreased continuously with increasing wavelength up to 380 nm. In the region between 380 and 440 nm there was a second maximum (at 415 nm) which corresponds to the maximum absorption of the fluorescing porphyrins in P. acnes. The sensitivity to 415 nm light was found to be dependent on the endogenous porphyrin concentration in the cells, while the sensitivity to 320 nm radiation was independent of the amount of porphyrin present. These results indicate that porphyrins produced by the bacteria are important for the light sensitivity of these bacteria. (author)

  2. Highly Efficient Cooperative Catalysis by Co III (Porphyrin) Pairs in Interpenetrating Metal-Organic Frameworks

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zekai; Zhang, Zhi-Ming; Chen, Yu-Sheng; Lin, Wenbin (UC); (Xiamen)

    2016-12-02

    A series of porous twofold interpenetrated In-CoIII(porphyrin) metal–organic frameworks (MOFs) were constructed by in situ metalation of porphyrin bridging ligands and used as efficient cooperative catalysts for the hydration of terminal alkynes. The twofold interpenetrating structure brings adjacent CoIII(porphyrins) in the two networks parallel to each other with a distance of about 8.8 Å, an ideal distance for the simultaneous activation of both substrates in alkyne hydration reactions. As a result, the In-CoIII(porphyrin) MOFs exhibit much higher (up to 38 times) catalytic activity than either homogeneous catalysts or MOF controls with isolated CoIII(porphyrin) centers, thus highlighting the potential application of MOFs in cooperative catalysis.

  3. Synthesis and properties of 5,10,15,20-tetra[4-(3,5-dioctoxybenzamidephenyl] porphyrin and its metal complexes

    Directory of Open Access Journals (Sweden)

    Lian Wenhui

    2012-01-01

    Full Text Available A novel 5,10,15,20-tetra[4-(3,5-dioctoxybenzamidephenyl]porphyrin and its transition metal complexes are reported in this paper. Their molecular structures were characterized by elemental analysis, IR spectra, 1HNMR spectra and UV-Vis spectra. Their spectroscopic properties were studied by Raman spectra, fluorescence spectra and X-ray photoelectron spectra (XPS. The fluorescence quantum yields have been measured at room temperature. The fluorescence intensity of porphyrin ligand was stronger than that of the complexes. In Raman spectra, there was much difference between porphyrin ligand and its metal complexes due to changes of the symmetry of porphyrin plane. In the XPS spectra, the replacement of the free-base protons by a metal ion to form the metalloporphyrin increases the symmetry of the molecule also introduces an electron with-drawing group into the center of the porphyrin ligand which increases the N1s binding energy.

  4. Evidence for porphyrins bound, via ester bonds, to the Messel oil shale kerogen by selective chemical degradation experiments

    Science.gov (United States)

    Huseby, B.; Ocampo, R.

    1997-09-01

    High amounts of nickel mono- and di-acid porphyrins were released from Messel oil shale kerogen (Eocene, Germany) by selective chemical degradation (acid and base hydrolysis). The released porphyrin fractions were quantified (UV-vis) and their constituents isolated and characterized at the molecular level (UV-vis, MS, NMR). The mono-acid porphyrin fraction released contained four compounds of similar abundance which arise from an obvious chlorophyll or bacteriochlorophyll precursor. The di-acid porphyrin fraction was, however, dominated by far by one compound, mesoporphyrin IX, which must have originated from heme-like precursors (heme, cytochromes, etc.). These results show unambigously that the released mono- and di-acid porphyrins were linked to the macromolecular kerogen network via ester bonds and suggest that precursor heme-like pigments could be selectively and/or more readily incorporated into the macromolecular kerogen network than precursor chlorophylls and bacteriochlorophylls.

  5. A NEW EMPIRICAL INVESTIGATION OF THE PLATINUM SPOT RETURNS

    Directory of Open Access Journals (Sweden)

    Simone Kruse

    2017-08-01

    Full Text Available The global platinum market has been in downturn and unstable for five consecutive years, and thus market participants are demanding effective quantitative risk management tools. Since platinum is so widely used and serves as an important investment vehicle, the importance of risk management of platinum spot returns cannot be understated. In this paper, we take advantage of a very popular econometric model, the generalized autoregressive conditional heteroscedasticity (GARCH model, for platinum returns. We received two important findings by using the conventional GARCH models in explain daily platinum spot returns. First, it is crucial to introduce heavy-tailed distribution to explain conditional heavy tails; and second, the NRIG distribution performs better than the most widely-used heavy-tailed distribution, the Student’s t distribution.

  6. Improved sensitivity of a graphene FET biosensor using porphyrin linkers

    Science.gov (United States)

    Kawata, Takuya; Ono, Takao; Kanai, Yasushi; Ohno, Yasuhide; Maehashi, Kenzo; Inoue, Koichi; Matsumoto, Kazuhiko

    2018-06-01

    Graphene FET (G-FET) biosensors have considerable potential due to the superior characteristics of graphene. Realizing this potential requires judicious choice of the linker molecule connecting the target-specific receptor molecule to the graphene surface, yet there are few reports comparing linker molecules for G-FET biosensors. In this study, tetrakis(4-carboxyphenyl)porphyrin (TCPP) was used as a linker for surface modification of a G-FET and the properties of the device were compared to those of a G-FET device modified with the conventional linker 1-pyrenebutanoic acid succinimidyl ester (PBASE). TCPP modification resulted in a higher density of receptor immunoglobulin E (IgE) aptamer molecules on the G-FET. The detection limit of the target IgE was enhanced from 13 nM for the PBASE-modified G-FET to 2.2 nM for the TCPP-modified G-FET, suggesting that the TCPP linker is a powerful candidate for G-FET modification.

  7. Modulating the electronic properties of asymmetric push–pull and symmetric Zn(II)-diarylporphyrinates with para substituted phenylethynyl moieties in 5,15 meso positions: A combined electrochemical and spectroscopic investigation

    International Nuclear Information System (INIS)

    Mussini, Patrizia Romana; Orbelli Biroli, Alessio; Tessore, Francesca; Pizzotti, Maddalena; Biaggi, Cinzia; Di Carlo, Gabriele; Lobello, Maria Grazia; De Angelis, Filippo

    2012-01-01

    Graphical abstract: - Abstract: Push–pull Zn(II)-porphyrinates have recently shown attracting performances as light harvesting systems in dye-sensitized solar cells (DSSCs). To fully exploit their intrinsically high efficiency it is important to finely tune their HOMO and LUMO levels, which can be achieved by proper choice of the push and pull substituents. Of course such target-oriented molecular design requires the availability of reliable relationships between molecular structure and electronic properties; therefore we have carried out a combined electrochemical, spectroscopic and computational investigation on a wide, systematic range of Zn(II)-porphyrinates 5,15 meso substituted with phenylethynyl linkers, including a first symmetric series carrying on the opposite terminals the same substituent (-N(CH 3 ) 2 , -OCH 3 , -COOCH 3 , -COOH, -NO 2 ); and a second push–pull one, with the terminal positions carrying one donor and one acceptor group belonging to the series above. Moreover, two suitably modified porphyrins allowed evaluation of the effects of (i) the presence or absence of the phenyl group in the linker between the porphyrin core and the acceptor group, and (ii) the effect of perfluorination on the same phenyl group. A rationalization scheme is proposed encompassing the whole porphyrin set, affording inter alia interesting clues on the different localization of the redox centres and effective conjugation between the porphyrin core and the side chains as a function of the molecular design.

  8. Porphyrin-phospholipid interaction and ring metallation depending on the phospholipid polar head type.

    Science.gov (United States)

    Ramos, Ana P; Pavani, Christiane; Iamamoto, Yassuko; Zaniquelli, Maria E D

    2010-10-01

    The interaction between a hydrophobically modified 5,10,15,20-tetrakis(4-N-tetradecyl-pyridyl) porphyrin and three phospholipids: two negatively charged, DMPA (the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid) and DMPG (the sodium salt of 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)]) and a zwitterionic DMPC (dimyristoyl-sn-glycero-phosphatidylcholine), were studied by means of surface pressure isotherms and spectroscopic methods. The interaction results in partial or total metallation of the porphyrin with zinc ions in the presence of negatively charged phospholipids, as attested by UV-vis and luminescence spectroscopy of the transferred films. In the presence of the zwitterionic phospholipid no insertion of zinc ion in the porphyrin ring is detected. These results are relevant for the understanding of photosensitizer-lipid-carrier binding for use in photodynamic therapy. Copyright 2010 Elsevier Inc. All rights reserved.

  9. Single site porphyrine-like structures advantages over metals for selective electrochemical CO2 reduction

    DEFF Research Database (Denmark)

    Bagger, Alexander; Ju, Wen; Varela, Ana Sofia

    2017-01-01

    Currently, no catalysts are completely selective for the electrochemical CO2 Reduction Reaction (CO2RR). Based on trends in density functional theory calculations of reaction intermediates we find that the single metal site in a porphyrine-like structure has a simple advantage of limiting...... the competing Hydrogen Evolution Reaction (HER). The single metal site in a porphyrine-like structure requires an ontop site binding of hydrogen, compared to the hollow site binding of hydrogen on a metal catalyst surface. The difference in binding site structure gives a fundamental energy-shift in the scaling...... relation of ∼0.3eV between the COOH* vs. H* intermediate (CO2RR vs. HER). As a result, porphyrine-like catalysts have the advantage over metal catalyst of suppressing HER and enhancing CO2RR selectivity....

  10. Heterogeneous biomimetic catalysis using iron porphyrin for cyclohexane oxidation promoted by chitosan

    Science.gov (United States)

    Huang, Guan; Liu, Yao; Cai, Jing Li; Chen, Xiang Feng; Zhao, Shu Kai; Guo, Yong An; Wei, Su Juan; Li, Xu

    2017-04-01

    This study investigates how ligands modulate metalloporphyrin activity with the goal of producing a practical biomimetic catalyst for use in the chemical industry. We immobilized iron porphyrinate [iron-tetrakis-(4-sulfonatophenyl)-porphyrin; Fe(III) (TPPS)] on powdered chitosan (pd-CTS) to form an immobilized catalyst Fe(III) (TPPS)/pd-CTS, which was characterized using modern spectroscopic techniques and used for catalytic oxidation of cyclohexane with O2. Amino coordination to iron porphyrin in Fe(III) (TPPS)/pd-CTS altered the electron cloud density around the iron cation, probably by reducing the activation energy of Fe(III) (TPPS) and raising the reactivity of the iron ion catalytic center, thereby improving the catalytic efficiency. One milligram of Fe(III) (TPPS) catalyst can be reused three times for the oxidation reaction to yield an average of 22.9 mol% of cyclohexanone and cyclohexanol.

  11. NANOSTRUCTURED TiO2 SENSITIZED WITH PORPHYRINS FOR SOLAR WATER-SPLITTING

    Directory of Open Access Journals (Sweden)

    MARCELA-CORINA ROŞU

    2011-03-01

    Full Text Available Nanostructured TiO2 sensitized with porphyrins for Solar water-splitting.The production of hydrogen from water using solar light is very promising for generations of an ecologically pure carrier contributing to a clean, sustainable and renewable energy system. The selection of specific photocatalyst material for hydrogen production in photoelectrochemical cells (PECs is based on some important characteristics of semiconductor, such as photo-corrosion and chemical corrosion stability, photocatalytic potential, high sensitivity for UV-visible light. In the present paper, different nanocrystalline TiO2 photoanodes have been prepared via wet-chemical techniques followed by annealing treatment and sensitized with porphyrins and supramolecular complexes of porphyrins. The so obtained photocatalysts were characterized with UV-VIS absorption spectroscopy and spectrofluorimetry. The purpose of these experiments is to show if the prepared materials possess the necessary photocatalytic characteristics and if they can be used with success in H2 production from water decomposition in PECs.

  12. Effects of p-substituents on electrochemical CO oxidation by Rh porphyrin-based catalysts.

    Science.gov (United States)

    Yamazaki, Shin-ichi; Yamada, Yusuke; Takeda, Sahori; Goto, Midori; Ioroi, Tsutomu; Siroma, Zyun; Yasuda, Kazuaki

    2010-08-21

    Electrochemical CO oxidation by several carbon-supported rhodium tetraphenylporphyrins with systematically varied meso-substituents was investigated. A quantitative analysis revealed that the p-substituents on the meso-phenyl groups significantly affected CO oxidation activity. The electrocatalytic reaction was characterized in detail based on the spectroscopic and X-ray structural results as well as electrochemical analyses. The difference in the activity among Rh porphyrins is discussed in terms of the properties of p-substituents along with a proposed reaction mechanism. Rhodium tetrakis(4-carboxyphenyl)porphyrin (Rh(TCPP)), which exhibited the highest activity among the porphyrins tested, oxidized CO at a high rate at much lower potentials (means that CO is electrochemically oxidized by this catalyst when a slight overpotential is applied during the operation of a proton exchange membrane fuel cell. This catalyst exhibited little H(2) oxidation activity, in contrast to Pt-based catalysts.

  13. Segregation of the elements of the platinum group in a simulated high-level waste glass

    International Nuclear Information System (INIS)

    Mitamura, H.; Banba, T.; Kamizono, H.; Kiriyama, Y.; Kumata, M.; Murakami, T.; Tashiro, S.

    1983-01-01

    Segregation of the elements of the platinum group occurred during vitrification of the borosilicate glass containing 20 wt% simulated high-level waste oxides. The segregated materials were composed of two crystalline phases: one was the solid solution of ruthenium and rhodium dioxides and the other was that of palladium and rhodium metals also with tellurium. The segregated materials were not distributed homogeneously throughout the glass: (i) on the surface of the glass, there occurred palladium, rhodium and tellurium alloy alone; and (ii) at the inner part of the glass, the agglomerates of the two phases were concentrated in one part and dispersed in the other

  14. Cutaneous porphyrins exhibit anti-stokes fluorescence that is detectable in sebum (Conference Presentation)

    Science.gov (United States)

    Tian, Giselle; Zeng, Haishan; Zhao, Jianhua; Wu, Zhenguo; Al Jasser, Mohammed; Lui, Harvey; Mclean, David I.

    2016-02-01

    Porphyrins produced by Propionibacterium acnes represent the principal fluorophore associated with acne, and appear as orange-red luminescence under the Wood's lamp. Assessment of acne based on Wood's lamp (UV) or visible light illumination is limited by photon penetration depth and has limited sensitivity for earlier stage lesions. Inducing fluorescence with near infrared (NIR) excitation may provide an alternative way to assess porphyrin-related skin disorders. We discovered that under 785 nm CW laser excitation PpIX powder exhibits fluorescence emission in the shorter wavelength range of 600-715 nm with an intensity that is linearly dependent on the excitation power. We attribute this shorter wavelength emission to anti-Stokes fluorescence. Similar anti-Stokes fluorescence was also detected focally in all skin-derived samples containing porphyrins. Regular (Stokes) fluorescence was present under UV and visible light excitation on ex vivo nasal skin and sebum from uninflamed acne, but not on nose surface smears or sebum from inflamed acne. Co-registered CW laser-excited anti-Stokes fluorescence and fs laser-excited multi-photon fluorescence images of PpIX powder showed similar features. In the skin samples because of the anti-Stokes effect, the NIR-induced fluorescence was presumably specific for porphyrins since there appeared to be no anti-Stokes emission signals from other typical skin fluorophores such as lipids, keratins and collagen. Anti-Stokes fluorescence under NIR CW excitation is more sensitive and specific for porphyrin detection than UV- or visible light-excited regular fluorescence and fs laser-excited multi-photon fluorescence. This approach also has higher image contrast compared to NIR fs laser-based multi-photon fluorescence imaging. The anti-Stokes fluorescence of porphyrins within sebum could potentially be applied to detecting and targeting acne lesions for treatment via fluorescence image guidance.

  15. Intramolecular Oxidative O-Demethylation of an Oxoferryl Porphyrin Complexed with a Per-O-methylated β-Cyclodextrin Dimer.

    Science.gov (United States)

    Kitagishi, Hiroaki; Kurosawa, Shun; Kano, Koji

    2016-11-22

    The intramolecular oxidation of ROCH 3 to ROCH 2 OH, where the latter compound spontaneously decomposed to ROH and HCHO, was observed during the reaction of the supramolecular complex (met-hemoCD3) with cumene hydroperoxide in aqueous solution. Met-hemoCD3 is composed of meso-tetrakis(4-sulfonatophenyl)porphinatoiron(III) (Fe III TPPS) and a per-O-methylated β-cyclodextrin dimer having an -OCH 2 PyCH 2 O- linker (Py=pyridine-3,5-diyl). The O=Fe IV TPPS complex was formed by the reaction of met-hemoCD3 with cumene hydroperoxide, and isolated by gel-filtration chromatography. Although the isolated O=Fe IV TPPS complex in the cyclodextrin cage was stable in aqueous solution at 25 °C, it was gradually converted to Fe II TPPS (t 1/2 =7.6 h). This conversion was accompanied by oxidative O-demethylation of an OCH 3 group in the cyclodextrin dimer. The results indicated that hydrogen abstraction by O=Fe IV TPPS from ROCH 3 yields HO-Fe III TPPS and ROCH 2 . . This was followed by radical coupling to afford Fe II TPPS and ROCH 2 OH. The hemiacetal (ROCH 2 OH) immediately decomposed to ROH and HCHO. This study revealed the ability of oxoferryl porphyrin to induce two-electron oxidation. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Singlet and Triplet Excitation Management in a Bichromophoric Near-Infrared-Phosphorescent BODIPY-Benzoporphyrin Platinum Complex

    KAUST Repository

    Whited, Matthew T.

    2011-01-12

    Multichromophoric arrays provide one strategy for assembling molecules with intense absorptions across the visible spectrum but are generally focused on systems that efficiently produce and manipulate singlet excitations and therefore are burdened by the restrictions of (a) unidirectional energy transfer and (b) limited tunability of the lowest molecular excited state. In contrast, we present here a multichromophoric array based on four boron dipyrrins (BODIPY) bound to a platinum benzoporphyrin scaffold that exhibits intense panchromatic absorption and efficiently generates triplets. The spectral complementarity of the BODIPY and porphryin units allows the direct observation of fast bidirectional singlet and triplet energy transfer processes (k ST(1BDP→1Por) = 7.8×1011 s-1, kTT(3Por→3BDP) = 1.0×1010 s-1, kTT(3BDP→ 3Por) = 1.6×1010 s-1), leading to a long-lived equilibrated [3BDP][Por]=[BDP][3Por] state. This equilibrated state contains approximately isoenergetic porphyrin and BODIPY triplets and exhibits efficient near-infrared phosphorescence (λem = 772 nm, φ = 0.26). Taken together, these studies show that appropriately designed triplet-utilizing arrays may overcome fundamental limitations typically associated with core-shell chromophores by tunable redistribution of energy from the core back onto the antennae. © 2010 American Chemical Society.

  17. Biomimetic oxidation of carbamazepine with hydrogen peroxide catalyzed by a manganese porphyrin

    Directory of Open Access Journals (Sweden)

    Cláudia M. B. Neves

    2012-01-01

    Full Text Available This laboratory project is planned for an undergraduate chemistry laboratory in which students prepare a manganese porphyrin able to mimic the oxidative metabolism of carbamazepine, one of the most frequently prescribed drugs in the treatment of epilepsy. The in vitro oxidation of carbamazepine results in the formation of the corresponding 10,11-epoxide, the main in vivo metabolite. The reaction is catalyzed by manganese porphyrin in the presence of H2O2, an environmentally-friendly oxidant. Through this project students will develop their skills in organic synthesis, coordination chemistry, chromatographic techniques such as TLC and HPLC, UV-visible spectrophotometry, and NMR spectroscopy.

  18. Biomimetic oxidation of carbamazepine with hydrogen peroxide catalyzed by a manganese porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Claudia M.B.; Simoes, Mario M.Q.; Domingues, Fernando M.J.; Neves, M. Graca P.M.S.; Cavaleiro, Jose A.S., E-mail: msimoes@ua.pt [Dept. de Quimica, QOPNA, Universidade de Aveiro (Portugal)

    2012-07-01

    This laboratory project is planned for an undergraduate chemistry laboratory in which students prepare a manganese porphyrin able to mimic the oxidative metabolism of carbamazepine, one of the most frequently prescribed drugs in the treatment of epilepsy. The in vitro oxidation of carbamazepine results in the formation of the corresponding 10,11-epoxide, the main in vivo metabolite. The reaction is catalyzed by manganese porphyrin in the presence of H{sub 2}O{sub 2}, an environmentally-friendly oxidant. Through this project students will develop their skills in organic synthesis, coordination chemistry, chromatographic techniques such as TLC and HPLC, UV-visible spectrophotometry, and NMR spectroscopy. (author)

  19. Platinum Group Thiophenoxyimine Complexes: Syntheses,Crystallographic and Computational Studies of Structural Properties

    Energy Technology Data Exchange (ETDEWEB)

    Krinsky, Jamin L.; Arnold, John; Bergman, Robert G.

    2006-10-03

    Monomeric thiosalicylaldiminate complexes of rhodium(I) and iridium(I) were prepared by ligand transfer from the homoleptic zinc(II) species. In the presence of strongly donating ligands, the iridium complexes undergo insertion of the metal into the imine carbon-hydrogen bond. Thiophenoxyketimines were prepared by non-templated reaction of o-mercaptoacetophenone with anilines, and were complexed with rhodium(I), iridium(I), nickel(II) and platinum(II). X-ray crystallographic studies showed that while the thiosalicylaldiminate complexes display planar ligand conformations, those of the thiophenoxyketiminates are strongly distorted. Results of a computational study were consistent with a steric-strain interpretation of the difference in preferred ligand geometries.

  20. Corrosion Studies of Platinum Nano-Particles for Fuel Cells

    DEFF Research Database (Denmark)

    Shim, Signe Sarah

    The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been character......The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been...... characterized during oxygen reduction reaction (ORR) condition using identical location (IL) transmission electron microscopy (TEM). A TEM grid was used as the working electrode in an electrochemical setup allowing a direct correlation between the electrochemical response and the TEM analysis. The main results...... thirds and one monolayer of gold on platinum supported on carbon were synthesized by an inverse micelle method. The results obtained appear independent of the gold coverage. It has been shown that the electrochemical active surface areas of the platinum and platinum gold particles synthesized...

  1. Physical studies of porphyrin-infiltrated opal crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sabataityte, J. [Semiconductor Physics Institute, Gostauto 11, LT 01108 Vilnius (Lithuania)], E-mail: julija@pfi.lt; Simkiene, I.; Babonas, G.-J.; Reza, A. [Semiconductor Physics Institute, Gostauto 11, LT 01108 Vilnius (Lithuania); Baran, M.; Szymczak, R. [Institute of Physics, PAN, PL 02668, Warsaw (Poland); Vaisnoras, R.; Rasteniene, L. [Vilnius Pedagogical University, LT 08106, Vilnius (Lithuania); Golubev, V.; Kurdyukov, D. [Ioffe Physico-Technical Institute RAS, 194021, St. Petersburg (Russian Federation)

    2007-09-15

    Artificial opals made of silica spheres and infiltrated with aqueous solution of iron porphyrin (FeTPPS) possessing the absorption band in a visible spectral range were studied. The structural, optical and magnetic properties of composite structures were investigated. Bulk samples of opal structure were obtained by sedimentation technique from colloidal solution of SiO{sub 2} spheres of diameter 240 and 245 nm. The structure of the samples was examined by atomic force microscopy. The properties of photonic crystals were demonstrated by optical measurements in transmission and reflection modes. The stop band was observed in the region 510-550 nm. In samples annealed at 900 deg. C the width of the stop band increased to {approx} 70 nm. Aqueous solutions of FeTPPS of concentration {approx} 1.0 mM and various pH-values were used for infiltration. The infiltration has led to a change of photonic characteristics, position of the stop band and dependence on light incidence angle. The absorption bands typical of FeTPPS were observed in the vicinity of the stop band. The photonic properties of infiltrated opal structures were determined to depend on the acidity of aqueous solution, which was used in technological procedure. Magnetic properties of FeTPPS-infiltrated opal samples, which have been studied at 5-300 K in magnetic fields up to 5 T, were discussed. From magnetic measurements it followed that magnetic Fe-Fe interactions have practically vanished in hybrid samples and Fe centers should be treated as isolated ones.

  2. Physical studies of porphyrin-infiltrated opal crystals

    International Nuclear Information System (INIS)

    Sabataityte, J.; Simkiene, I.; Babonas, G.-J.; Reza, A.; Baran, M.; Szymczak, R.; Vaisnoras, R.; Rasteniene, L.; Golubev, V.; Kurdyukov, D.

    2007-01-01

    Artificial opals made of silica spheres and infiltrated with aqueous solution of iron porphyrin (FeTPPS) possessing the absorption band in a visible spectral range were studied. The structural, optical and magnetic properties of composite structures were investigated. Bulk samples of opal structure were obtained by sedimentation technique from colloidal solution of SiO 2 spheres of diameter 240 and 245 nm. The structure of the samples was examined by atomic force microscopy. The properties of photonic crystals were demonstrated by optical measurements in transmission and reflection modes. The stop band was observed in the region 510-550 nm. In samples annealed at 900 deg. C the width of the stop band increased to ∼ 70 nm. Aqueous solutions of FeTPPS of concentration ∼ 1.0 mM and various pH-values were used for infiltration. The infiltration has led to a change of photonic characteristics, position of the stop band and dependence on light incidence angle. The absorption bands typical of FeTPPS were observed in the vicinity of the stop band. The photonic properties of infiltrated opal structures were determined to depend on the acidity of aqueous solution, which was used in technological procedure. Magnetic properties of FeTPPS-infiltrated opal samples, which have been studied at 5-300 K in magnetic fields up to 5 T, were discussed. From magnetic measurements it followed that magnetic Fe-Fe interactions have practically vanished in hybrid samples and Fe centers should be treated as isolated ones

  3. Fiber optic fluorescence detection of low-level porphyrin concentrations in preclinical and clinical studies

    Science.gov (United States)

    Mang, Thomas S.; McGinnis, Carolyn; Khan, S.

    1990-07-01

    A significant clinical problem in the local treatment of cutaneous metastases of breast cancer (by any modality--surgery, radiation therapy or photodynainic therapy) is the fact that the disease almost always extends beyond the boundary of visible lesions in the form of microscopic deposits. These deposits may be distant from the site of visible disease but are often in close proximity to it and are manifested sooner or later by the development of recurrent lesions at the border of the treated area, thus the "marginal miss" in radiation therapy, the "rim recurrence" in photodynamic therapy, and the "incisional recurrence" following surgical excision. More intelligent use of these treatment modalities demands the ability to detect microscopic deposits of tumor cells using non-invasive methodology. In vivo fluorescence measurements have been made possible by the development of an extremely sensitive fiber optic in vivo fluorescence photometer. The instrument has been used to verify that fluorescence correlated with injected porphyrin levels in various tissues. The delivery of light to excite and detect background fluorescence as well as photosensitizer fluorescence in tissues has been accomplished using two HeNe lasers emitting at 632.8 nm and 612 nm delivered through a single quartz fiber optic. Chopping at different frequencies, contributions of fluorescence may be separated. Fluorescence is picked up via a 400 micron quartz fiber optic positioned appropriately near the target tissue. Validation of these levels was made by extraction of the drug from the tissues with resultant quantitation. Recently, an extensive study was undertaken to determine if fluorescence could be used for the detection of occult, clinically non-palpable metastases in the lymph node of rats. This unique model allowed for the detection of micrometastases in lymph nodes using very low injected doses of the photosensitizer Photofrin II. Data obtained revealed the ability to detect on the order

  4. Conformational switching of ethano-bridged Cu,H2-bis-porphyrin induced by aromatic amines.

    Science.gov (United States)

    Bettini, Simona; Maglie, Emanuela; Pagano, Rosanna; Borovkov, Victor; Inoue, Yoshihisa; Valli, Ludovico; Giancane, Gabriele

    2015-01-01

    Cu,H2-bis-porphyrin (Cu,H2-Por2), in which copper porphyrin and free-base porphyrin are linked together by an ethano-bridge, was dissolved in chloroform and spread at the air/liquid subphase interface of a Langmuir trough. The bis-porphyrin derivative, floating film was characterized by reflection spectroscopy and the surface pressure of the floating film was studied as a function of the mean area per molecule. When aromatic amines are dissolved in the subphase, an evident interaction between the bis-porphyrin host and the aromatic amine guest is observed. A clear-cut variation of the profile of surface pressure vs area per molecule curve is observed. Reflection spectroscopy highlights that the aromatic amines dissolved in the subphase are able to induce the syn-to-anti conformational switching in the bis-porphyrin derivative. The Langmuir-Schaefer technique has been used to transfer the floating bis-porphyrin film (when using pure water as a subphase) to a surface plasmon resonance (SPR) substrate and the resulting device was able to detect the presence of aniline at concentrations as low as 1 nM in aqueous solution. The high selectivity of the SPR sensing device has been verified by checking the spectral response of the active layer towards other analytes dissolved in the aqueous solutions.

  5. Conformational switching of ethano-bridged Cu,H2-bis-porphyrin induced by aromatic amines

    Directory of Open Access Journals (Sweden)

    Simona Bettini

    2015-11-01

    Full Text Available Cu,H2-bis-porphyrin (Cu,H2-Por2, in which copper porphyrin and free-base porphyrin are linked together by an ethano-bridge, was dissolved in chloroform and spread at the air/liquid subphase interface of a Langmuir trough. The bis-porphyrin derivative, floating film was characterized by reflection spectroscopy and the surface pressure of the floating film was studied as a function of the mean area per molecule. When aromatic amines are dissolved in the subphase, an evident interaction between the bis-porphyrin host and the aromatic amine guest is observed. A clear-cut variation of the profile of surface pressure vs area per molecule curve is observed. Reflection spectroscopy highlights that the aromatic amines dissolved in the subphase are able to induce the syn-to-anti conformational switching in the bis-porphyrin derivative. The Langmuir–Schaefer technique has been used to transfer the floating bis-porphyrin film (when using pure water as a subphase to a surface plasmon resonance (SPR substrate and the resulting device was able to detect the presence of aniline at concentrations as low as 1 nM in aqueous solution. The high selectivity of the SPR sensing device has been verified by checking the spectral response of the active layer towards other analytes dissolved in the aqueous solutions.

  6. Dissolution of Platinum in Hydrochloric Acid Under Industrial-Scale Alternating Current Polarization

    Science.gov (United States)

    Myrzabekov, B. E.; Bayeshov, A. B.; Makhanbetov, A. B.; Mishra, B.; Baigenzhenov, O. S.

    2018-02-01

    The electrochemical behavior of platinum in a hydrochloric acid solution under polarization by an industrial-scale alternating current has been investigated. For the electrical dissolution of platinum, titanium is used as an auxiliary electrode, which increases the yield of platinum dissolution by 12.5 pct. The influence of the concentration of hydrochloric acid, the current densities of the platinum and titanium electrodes, and the temperature of the electrolyte on the efficiency of the process of dissolving platinum have all been studied.

  7. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer N. [Univ. of California, San Diego, CA (United States); Wang, Joseph [Univ. of California, San Diego, CA (United States)

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  8. The RSC Faraday prize lecture of 1989 on platinum.

    Science.gov (United States)

    Thomas, John Meurig

    2017-08-25

    In 1861, Michael Faraday gave one of his last Friday Evening Discourses at the Royal Institution of Great Britain, London, on platinum, which he described as "this beautiful, magnificent and valuable metal". More than a hundred and twenty years later (in 1989), the author re-enacted, at the Royal Institution, many of the demonstrations that Faraday carried out in his memorable Discourse. This article outlines many of Faraday's views on, and experiments with, platinum. It also describes the continuing importance and utilization of platinum, both as perceived in 1989 and from present perspectives.

  9. Synthesis And Characterization Of 6,6'-Bis (2-Hydroxyphenyl)-2,2'-Bipyridyl Ligand And Its Platinum Complex for the Interaction with CT-DNA

    International Nuclear Information System (INIS)

    Norhidayah Selamat; Heng, L.Y.; Nurul Izzaty Hassan; Nurul Huda Abd Karim

    2016-01-01

    A tetradentate ligand with four donor atoms OONN and its platinum metal complex were synthesized. Bis(phenoxy)bipyridine ligand was prepared by Suzuki coupling reaction between 6,6 ' -dibromo-2,2 ' -bipyridyl and 2-hydroxy phenylboronic acid with the presence of palladium (II) acetate. The formation of platinum complex was done by introducing the ligand with platinum (II) chloride in benzonitrile. Both ligand and complex structures were confirmed by 1 H, 2D cosy and 13 C NMR spectroscopy, ESIMS spectrometry and FTIR spectroscopy. Binding studies of small molecules with DNA are useful to understand the reaction mechanism and to provide guidance for the application and design of new and more efficient drugs or sensors targeted on DNA. In this study, the binding interaction between the synthesized ligand and complex with calf thymus DNA (CT-DNA) has been investigated using UV-Visible and emission DNA titration. From the UV-Visible DNA study, it showed that platinum (II) bipyridine complex had higher affinity towards CT-DNA with binding constant K b =(3.1 ± 0.02 x 10 5 ) ± 0.02 M -1 compared to that of bis(phenoxy) bipyridine ligand with binding constant (K b ) = (1.19 ± 0.08) x 10 3 M -1 . These findings will be valuable for the potential use of platinum (II) bipyridine complex as a phosphorescent probe in optical sensor DNA. (author)

  10. Platinum dendritic nanoparticles with magnetic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenxian, E-mail: wl240@uowmail.edu.au [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Solar Energy Technologies, School of Computing, Engineering, and Mathematics, University of Western Sydney, Penrith NSW 2751 (Australia); Sun, Ziqi; Nevirkovets, Ivan P.; Dou, Shi-Xue [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Tian, Dongliang [Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and the Environment, Beihang University, Beijing 100191 (China)

    2014-07-21

    Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ∼4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

  11. Superconductivity observed in platinum-silicon interface

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Pai-Chia, E-mail: paichia@phys.sinica.edu.tw [Research Program on Nanoscience and Nanotechnology, Academia Sinica, Taipei 11529, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Chun-Wei [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Lee, Ku-Pin; Shiue, Jessie, E-mail: yshiue@phys.sinica.edu.tw [Research Program on Nanoscience and Nanotechnology, Academia Sinica, Taipei 11529, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China)

    2014-05-26

    We report the discovery of superconductivity with an onset temperature of ∼0.6 K in a platinum-silicon interface. The interface was formed by using a unique focused ion beam sputtering micro-deposition method in which the energies of most sputtered Pt atoms are ∼2.5 eV. Structural and elemental analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy reveal a ∼ 7 nm interface layer with abundant Pt, which is the layer likely responsible for the superconducting transport behavior. Similar transport behavior was also observed in a gold-silicon interface prepared by the same technique, indicating the possible generality of this phenomenon.

  12. A platinum in-core flux detector

    International Nuclear Information System (INIS)

    Shields, R.B.

    1976-01-01

    The performance is described of a platinum emitter self-powered detector having the following parameters: emitter diameter 0.51 mm, Inconel 600 collector of 1.5 mm outer diameter and 0.25 mm wall thickness, compacted powder MgO insulant, thermal neutron flux 10 14 n.cm -2 .s -1 and gamma radiation dose rate 1.2 x 10 8 rad.h -1 . The advantage of the detector is its sensitivity to both neutrons and gamma radiation. A comparison is made with other types of detectors using Ce, Ta, Os, Rh, V, Co, Zr as emitters, especially in relation to the emitter response time to neutrons or gammas, the output signal amplitude, sensitivity, and the emitter half-life. Extensive tests of the detectors proceeded for two years on the NRU and CANDU-BLW reactors in Gentilly, Canada. (J.B.)

  13. Platinum dendritic nanoparticles with magnetic behavior

    International Nuclear Information System (INIS)

    Li, Wenxian; Sun, Ziqi; Nevirkovets, Ivan P.; Dou, Shi-Xue; Tian, Dongliang

    2014-01-01

    Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ∼4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

  14. Physical origin of third order non-linear optical response of porphyrin nanorods

    International Nuclear Information System (INIS)

    Mongwaketsi, N.; Khamlich, S.; Pranaitis, M.; Sahraoui, B.; Khammar, F.; Garab, G.; Sparrow, R.; Maaza, M.

    2012-01-01

    The non-linear optical properties of porphyrin nanorods were studied using Z-scan, Second and Third harmonic generation techniques. We investigated in details the heteroaggregate behaviour formation of [H 4 TPPS 4 ] 2- and [SnTPyP] 2+ mixture by means of the UV-VIS spectroscopy and aggregates structure and morphology by transmission electron microscopy. The porphyrin nanorods under investigation were synthesized by self assembly and molecular recognition method. They have been optimized in view of future application in the construction of the light harvesting system. The focus of this study was geared towards understanding the influence of the type of solvent used on these porphyrins nanorods using spectroscopic and microscopic techniques. Highlights: ► We synthesized porphyrin nanorods by self assembly and molecular recognition method. ► TEM images confirmed solid cylindrical shapes. ► UV-VIS spectroscopy showed the decrease in the absorbance peaks of the precursors. ► The enhanced third-order nonlinearities were observed.

  15. Synthesis, characterization, and nonlinear optical properties of graphene oxide functionalized with tetra-amino porphyrin

    Science.gov (United States)

    Yamuna, R.; Ramakrishnan, S.; Dhara, Keerthy; Devi, R.; Kothurkar, Nikhil K.; Kirubha, E.; Palanisamy, P. K.

    2013-01-01

    The synthesis of a porphyrin-graphene oxide hybrid (GO-TAP) was carried out by covalently functionalizing graphene oxide (GO) with 5,10,15,20 mesotetra (4-aminophenyl) porphyrin (TAP) through an amide linkage. The GO-TAP hybrid has been characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-visible spectroscopy. The peak intensity of the Soret band of the material was suppressed compared to neat TAP. This indicates a strong interaction between the electronic energy level of TAP and GO in the GO-TAP hybrid. The functionalization of GO with TAP significantly improved its solubility and dispersion stability in organic solvents. Scanning electron micrographs reveal that the hybrid was found to be similar to the unmodified GO but slightly more wrinkled. Transmission electron micrographs also demonstrate that GO sheet in the hybrid is more wrinkled with some dark spot due to functionalization. Atomic force microscopy results also reveal that the TAP functionalization increases the thickness of GO sheet to 2.0-3.0 nm from 1.2 to 1.8 nm. We observed improved nonlinear optical and optical limiting properties for the hybrid compared to both graphene oxide and porphyrin. GO-TAP shows fluorescence quenching compared with porphyrin, indicating excellent electron and/or energy transfer to GO from TAP. Thermogravimetric analysis confirms that the GO-TAP hybrid has outstanding thermal stability.

  16. Controlled electropolymerisation of a carbazole-functionalised iron porphyrin electrocatalyst for CO2 reduction

    DEFF Research Database (Denmark)

    Hu, Xinming; Salmi, Zakaria; Lillethorup, Mie

    2016-01-01

    Using a one-step electropolymerisation procedure, CO2 absorbing microporous carbazole-functionalised films of iron porphyrins are prepared in a controlled manner. The electrocatalytic reduction of CO2 for these films is investigated to elucidate their efficiency and the origin of their ultimate...

  17. N-annulated perylene fused porphyrins with enhanced near-IR absorption and emission

    KAUST Repository

    Jiao, Chongjun; Huang, Kuo-Wei; Guan, Zhenping; Xu, Qinghua; Wu, Jishan

    2010-01-01

    -IR absorption, as well as detectable photoluminescence quantum yields, all of which are comparable to or even exceed those of either meso-β doubly linked porphyrin dimer/trimer or bis/tri-N-annulated rylenes. © 2010 American Chemical Society.

  18. Aspects of investigating scrambling in the synthesis of porphyrins Different analytical methods

    DEFF Research Database (Denmark)

    Nielsen, C.B.; Krebs, Frederik C

    2005-01-01

    Herein, we discuss the analyses and quantification of the different components in porphyrin mixtures, prepared from p-anisaidehyde, p-tolualdehyde, and 5-(4-bromophenyl)-dipyrromethane with acid catalysis, using NMR and HPLC. The advantages and disadvantages of these analytical methods are emphas...

  19. Redox tuning of cytochrome b562 through facile metal porphyrin substitution

    DEFF Research Database (Denmark)

    Della Pia, Eduardo Antonio; Chi, Qijin; Elliott, Martin

    2012-01-01

    The biologically and nanotechnologically important heme protein cytochrome b562 was reconstructed with zinc and copper porphyrins, leading to significant changes in the spectral, redox and electron transfer properties. The Cu form shifts the redox potential by +300 mV and exhibits high electron t...

  20. Spectral Sensitization of TiO2 Substrates by Monolayers of Porphyrin Heterodimers

    NARCIS (Netherlands)

    Koehorst, R.B.M.; Boschloo, G.K.; Savenije, T.J.; Goossens, A.; Schaafsma, T.J.

    2000-01-01

    Photoelectrochemical cells have been constructed by depositing monolayers of oriented covalently linked zinc/free base porphyrin heterodimers onto ~30 nm nonporous layers of TiO2 on ITO, deposited by metal-organic chemical vapor deposition (MO-CVD), and onto ~100 nm porous, nanostructured TiO2

  1. New ZnO@Cardanol Porphyrin Composite Nanomaterials with Enhanced Photocatalytic Capability under Solar Light Irradiation

    Directory of Open Access Journals (Sweden)

    Viviane Gomes Pereira Ribeiro

    2017-09-01

    Full Text Available This work describes the synthesis, characterization, and photocatalytic activity of new composite nanomaterials based on ZnO nanostructures impregnated by lipophlilic porphyrins derived from cashew nut shell liquid (CNSL. The obtained nanomaterials were characterized by X-ray diffraction (XRD, UV-Vis diffuse reflectance spectroscopy (DRS, Fourier transform infrared spectroscopy (FT-IR, transmission electron microscopy (TEM, and steady-state photoluminescence spectra (PL. The results confirm nanostructures showing average diameter of 55 nm and an improved absorption in the visible region. Further, the FTIR analysis proved the existence of non-covalent interactions between the porphyrin molecules and ZnO. The photocatalytic activity of prepared photocatalysts was investigated by degradation of rhodamine B (RhB in aqueous solution under visible light irradiation and natural sunlight. It was demonstrated that the photocatalytic activity increases in the presence of the porphyrins and, also, depends on the irradiation source. The development of composite photocatalysts based on porphyrins derived from CNSL provides an alternative approach to eliminate efficiently toxic wastes from water under ambient conditions.

  2. Optical acetylcholine sensor based on free base porphyrin as a chromoionophore.

    Science.gov (United States)

    Mroczkiewicz, Monika; Pietrzak, Mariusz; Górski, Łukasz; Malinowska, Elżbieta

    2011-09-21

    In this work, the possibility of application of free base porphyrin as a lipophilic pH chromoionophore for the preparation of optical cation-selective sensors was investigated. The properties of polymeric membranes, containing porphyrins of different structures, namely tetraphenylporphyrin (TPP) and octaethylporphyrin (OEP), were compared. Changes in equilibrium between protonated and deprotonated form of porphyrin, resulting from variations in ACh concentration, were evaluated. The influence of various factors (kind and quantity of anionic additive and porphyrin in the membrane phase, pH of sample solution) on initial equilibrium was studied. The best membrane composition was chosen as: TPP 3 wt.%, KTFPB 175 mol.% relative to ionophore, PVC:o-NPOE (1 : 4) and measuring buffer solution: 0.05 M MES, pH 4.5. Selectivity, response stability, reversibility and repeatability tests were carried out for chosen sensor. Developed sensor allowed for the determination of a model analyte, acetylcholine, at the concentration range of 10(-5) to 10(-2) M, both in stationary and flow-injection system. Sensor response was reversible and repeatable in the mentioned concentration range.

  3. Spherical porphyrin sensor array based on encoded colloidal crystal beads for VOC vapor detection.

    Science.gov (United States)

    Xu, Hua; Cao, Kai-Di; Ding, Hai-Bo; Zhong, Qi-Feng; Gu, Hong-Cheng; Xie, Zhuo-Ying; Zhao, Yuan-Jin; Gu, Zhong-Ze

    2012-12-01

    A spherical porphyrin sensor array using colloidal crystal beads (CCBs) as the encoding microcarriers has been developed for VOC vapor detection. Six different porphyrins were coated onto the CCBs with distinctive encoded reflection peaks via physical adsorption and the sensor array was fabricated by placing the prepared porphyrin-modified CCBs together. The change in fluorescence color of the porphyrin-modified CCBs array serves as the detection signal for discriminating between different VOC vapors and the reflection peak of the CCBs serves as the encoding signal to distinguish between different sensors. It was demonstrated that the VOC vapors detection using the prepared sensor array showed excellent discrimination: not only could the compounds from the different chemical classes be easily differentiated (e.g., alcohol vs acids vs ketones) but similar compounds from the same chemical family (e.g., methanol vs ethanol) and the same compound with different concentration ((e.g., Sat. ethanol vs 60 ppm ethanol vs 10 ppm ethanol) could also be distinguished. The detection reproducibility and the humidity effect were also investigated. The present spherical sensor array, with its simple preparation, rapid response, high sensitivity, reproducibility, and humidity insensitivity, and especially with stable and high-throughput encoding, is promising for real applications in artificial olfactory systems.

  4. Chiral memory via chiral amplification and selective depolymerization of porphyrin aggregates

    NARCIS (Netherlands)

    Helmich, F.A.; Lee, C.C.; Schenning, A.P.H.J.; Meijer, E.W.

    2010-01-01

    Chiral memory at the supramolecular level is obtained via a new approach using chiral Zn porphrins and achiral Cu porphyrins. In a "sergeant-and-soldiers" experiment, the Zn "sergeant" transfers its own chirality to Cu "soldiers" and, after chiral amplification, the "sergeant" is removed from the

  5. Thermodynamic driving force effects in the oxygen reduction catalyzed by a metal-free porphyrin

    Czech Academy of Sciences Publication Activity Database

    Trojánek, Antonín; Langmaier, Jan; Samec, Zdeněk

    2012-01-01

    Roč. 82, SI (2012), s. 457-462 ISSN 0013-4686 R&D Projects: GA ČR GAP208/11/0697 Institutional research plan: CEZ:AV0Z40400503 Keywords : oxygen reduction * metal-free porphyrin * electrocatalysis Subject RIV: CG - Electrochemistry Impact factor: 3.777, year: 2012

  6. Porphyrin metabolism in lymphocytes of miners exposed to diesel exhaust at oil shale mine.

    NARCIS (Netherlands)

    Muzyka, V.; Scheepers, P.T.J.; Bogovski, S.; Lang, I.; Schmidt, N.; Ryazanov, V.; Veidebaum, T.

    2004-01-01

    The present study was carried out on the evaluation and application of new biomarkers for populations exposed to occupational diesel exhaust at oil shale mines. Since not only genotoxic effects may play an important role in the generation of tumors, the level of porphyrin metabolism was proposed as

  7. Synthesis and photophysical properties of phosphorus(V) porphyrins functionalized with axial carbazolylvinylnaphthalimides.

    Science.gov (United States)

    Zhan, Yong; Cao, Kaiyu; Wang, Chenguang; Jia, Junhui; Xue, Pengchong; Liu, Xingliang; Duan, Xuemei; Lu, Ran

    2012-11-21

    We have synthesized new D-A-D type phosphorus(V) porphyrin derivatives and functionalized with axial carbazolylvinylnaphthalimide units. The absorption bands of the obtained phosphorus(V) porphyrins were in the range 250-640 nm with high molar absorption coefficients, meaning strong light-harvesting abilities. Notably, it is found that the devices based on phosphorus(V) porphyrins with a configuration structure of [ITO/PEDOT : PSS/organic active film/LiF/Al] give an incident-photon-to-current conversion efficiency (IPCE) response. The maximal IPCE value reaches 2.76% for the device based on compound , which is much higher than that of 0.20% for compound . The reason might be due to the low oxidation potential and the strong light-harvesting ability of the enlarged conjugation of the axial units in compound . Therefore, we deduced that photo-induced electron transfer happened in phosphorus(V) porphyrins bearing axial conjugated donor units, which would make them good candidates for photovoltaic materials that could be applied in solar cells.

  8. Synthesis and photobactericidal properties of a neutral porphyrin grafted onto lignocellulosic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Nzambe Ta keki, Jean Kerim; Ouk, Tan-Sothéa [Laboratoire de chimie des substances naturelles, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France); Zerrouki, Rachida [Laboratoire de chimie des substances naturelles, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France); Centre de Recherche sur les Matériaux Lignocellulosiques, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7 (Canada); Faugeras, Pierre-Antoine; Sol, Vincent [Laboratoire de chimie des substances naturelles, Université de Limoges, 123 avenue Albert Thomas, 87060 Limoges (France); Brouillette, François [Centre de Recherche sur les Matériaux Lignocellulosiques, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7 (Canada)

    2016-05-01

    Photodynamic antimicrobial chemotherapy (PACT), as one of the promising alternative antimicrobial treatment, has received great attention in recent years. In this work, a new antimicrobial material has been elaborated by grafting a neutral porphyrin, the metallated 5-(4-azidophenyl)-10,15,20-triphenylporphyrin, onto lignocellulosic fibers by using the Copper (I)-Catalyzed Alkyne-Azide 1,3-dipolar Cycloaddition (CuAAC) reaction. The cross-linked porphyrin-Kraft pulp material was characterized by infrared and by XPS spectroscopy analyses, which proved the covalent linkage between the porphyrin and propargylated Kraft pulp fibers. The antimicrobial activity of this material was tested under visible light irradiation with a low light dose (9.5 J/cm{sup 2}) against Staphylococcus aureus and Pseudomonas aeruginosa. The two bacterial strains deposited on the resulting photosensitizing Kraft pulp are efficiently killed after illumination. Such materials could find applications in industrial, household and medical environments as an alternative to overcome the widespread microbial multiresistance to classical treatments. - Highlights: • Elaboration of new antimicrobial paper • Grafting of porphyrin on lignocellulosic fibers using click chemistry • Modification of Kraft pulp fibers, using water as solvent.

  9. Photokinetic and ultrastructural studies on porphyrin photosensitization of HeLa cells

    International Nuclear Information System (INIS)

    Milanesi, Carla; Sorgato, Fiorella; Jori, Giulio

    1989-01-01

    Liposome-bound haematoporphyrin or haematoporphyrin dimethylester, as well as haematoporphyrin dissolved in phosphate-buffered saline, were added to HeLa cell monolayers at a dose of 1 μg of porphyrin per 10 5 cells. After 2 min or 20 min incubation liposome-bound porphyrins were accumulated by cells in an about two-fold larger amount than the water-dissolved haematoporphyrin. This caused a more efficient photosensitization of HeLa cells by liposome-delivered porphyrins upon illumination with 366 nm light. Ultrastructural studies of HeLa cells, which had been incubated in a physiological medium for 24 h after the end of irradiation, showed that liposomal porphyrins induce an early and extensive endocytoplasmic damage, leading to mitochondrial swelling and vesiculation; changes of permeability of the cytoplasmic membrane are also evident, especially in the case of haematoporphyrin dimethylester. On the other hand, water-dissolved haematoporphyrin predominantly photosensitizes damage of the plasma membrane. The different pattern of cell photodamage probably reflects a different subcellular distribution of the photosensitizing drugs. (author)

  10. New ZnO@Cardanol Porphyrin Composite Nanomaterials with Enhanced Photocatalytic Capability under Solar Light Irradiation

    Science.gov (United States)

    Ribeiro, Viviane Gomes Pereira; Marcelo, Ana Maria Pereira; da Silva, Kássia Teixeira; da Silva, Fernando Luiz Firmino; Mota, João Paulo Ferreira; do Nascimento, João Paulo Costa; Sombra, Antonio Sérgio Bezerra; Clemente, Claudenilson da Silva; Mazzetto, Selma Elaine

    2017-01-01

    This work describes the synthesis, characterization, and photocatalytic activity of new composite nanomaterials based on ZnO nanostructures impregnated by lipophlilic porphyrins derived from cashew nut shell liquid (CNSL). The obtained nanomaterials were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and steady-state photoluminescence spectra (PL). The results confirm nanostructures showing average diameter of 55 nm and an improved absorption in the visible region. Further, the FTIR analysis proved the existence of non-covalent interactions between the porphyrin molecules and ZnO. The photocatalytic activity of prepared photocatalysts was investigated by degradation of rhodamine B (RhB) in aqueous solution under visible light irradiation and natural sunlight. It was demonstrated that the photocatalytic activity increases in the presence of the porphyrins and, also, depends on the irradiation source. The development of composite photocatalysts based on porphyrins derived from CNSL provides an alternative approach to eliminate efficiently toxic wastes from water under ambient conditions. PMID:28934117

  11. RAFT Synthesis and Self-Assembly of Free-Base Porphyrin Cored Star Polymers

    Directory of Open Access Journals (Sweden)

    Lin Wu

    2011-01-01

    Full Text Available Reversible addition fragmentation chain transfer (RAFT synthesis and self-assembly of free-base porphyrin cored star polymers are reported. The polymerization, in the presence of a free-base porphyrin cored chain transfer agent (CTA-FBP, produced porphyrin star polymers with controlled molecular weights and narrow polydispersities for a number of monomers including N, N-dimethylacrylamide (DMA and styrene (St. Well-defined amphiphilic star block copolymers, P-(PS-PDMA4 and P-(PDMA-PS4 (P: porphyrin, were also prepared and used for self-assembly studies. In methanol, a selective solvent for PDMA, spherical micelles were observed for both block copolymers as characterized by TEM. UV-vis studies suggested star-like micelles were formed from P-(PS-PDMA4, while P-(PDMA-PS4 aggregated into flower-like micelles. Spectrophotometric titrations indicated that the optical response of these two micelles to external ions was a function of micellar structures. These structure-related properties will be used for micelle studies and functional material development in the future.

  12. Competitive inhibition of a metal-free porphyrin oxygen-reduction catalyst by water

    Czech Academy of Sciences Publication Activity Database

    Trojánek, Antonín; Langmaier, Jan; Záliš, Stanislav; Samec, Zdeněk

    2012-01-01

    Roč. 48, č. 34 (2012), s. 4094-4096 ISSN 1359-7345 R&D Projects: GA ČR GAP208/11/0697 Institutional research plan: CEZ:AV0Z40400503 Keywords : metal -free porphyrin * competitive inhibition * liquid-liquid interfaces Subject RIV: CG - Electrochemistry Impact factor: 6.378, year: 2012

  13. Electrochemical CO2 and CO reduction on metal-functionalized porphyrin-like graphene

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Vanin, Marco; Karamad, Mohammedreza

    2013-01-01

    Porphyrin-like metal-functionalized graphene structures have been investigated as possible catalysts for CO2 and CO reduction to methane or methanol. The late transition metals (Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Fe, Ru, Os) and some p (B, Al, Ga) and s (Mg) metals comprised the center of the po......Porphyrin-like metal-functionalized graphene structures have been investigated as possible catalysts for CO2 and CO reduction to methane or methanol. The late transition metals (Cu, Ag, Au, Ni, Pd, Pt, Co, Rh, Ir, Fe, Ru, Os) and some p (B, Al, Ga) and s (Mg) metals comprised the center...... instead of CO2. Volcano plots were constructed on the basis of scaling relations of reaction intermediates, and from these plots the reaction steps with the highest overpotentials were deduced. The Rh-porphyrin-like functionalized graphene was identified as the most active catalyst for producing methanol...... from CO, featuring an overpotential of 0.22 V. Additionally, we have also examined the hydrogen evolution and oxidation reaction, and in their case, too, Rh-porphyrin turned out to be the best catalyst with an overpotential of 0.15 V. © 2013 American Chemical Society....

  14. NO2-induced synthesis of nitrato-iron(III) porphyrin with diverse ...

    Indian Academy of Sciences (India)

    found serendipitously in the reaction of [Fe(4-Me-TPP)Cl] with nitrous acid, which ... Nitric oxide and its derivatives nitrite and nitrate ion ... oxide.2 Nitrate is produced in heme proteins from oxi- ... and nitrogen assimilation.4 Iron nitrate(III) porphyrins ... one-pot method.15 ... of the compound was determined based on the lack.

  15. Mg-Al layered double hydroxide intercalated with porphyrin anions: molecular simulations and experiments

    Czech Academy of Sciences Publication Activity Database

    Kovář, P.; Pospíšil, M.; Káfuňková, Eva; Lang, Kamil; Kovanda, F.

    2010-01-01

    Roč. 16, č. 2 (2010), s. 223-233 ISSN 1610-2940 R&D Projects: GA ČR(CZ) GA203/06/1244; GA AV ČR KAN100500651 Institutional research plan: CEZ:AV0Z40320502 Keywords : layered double hydroxide * porphyrin * molecular simulations Subject RIV: CA - Inorganic Chemistry Impact factor: 1.871, year: 2010

  16. Transforming a Targeted Porphyrin Theranostic Agent into a PET Imaging Probe for Cancer

    Directory of Open Access Journals (Sweden)

    Jiyun Shi, Tracy W.B. Liu, Juan Chen, David Green, David Jaffray, Brian C. Wilson, Fan Wang, Gang Zheng

    2011-01-01

    Full Text Available Porphyrin based photosensitizers are useful agents for photodynamic therapy (PDT and fluorescence imaging of cancer. Porphyrins are also excellent metal chelators forming highly stable metallo-complexes making them efficient delivery vehicles for radioisotopes. Here we investigated the possibility of incorporating 64Cu into a porphyrin-peptide-folate (PPF probe developed previously as folate receptor (FR targeted fluorescent/PDT agent, and evaluated the potential of turning the resulting 64Cu-PPF into a positron emission tomography (PET probe for cancer imaging. Noninvasive PET imaging followed by radioassay evaluated the tumor accumulation, pharmacokinetics and biodistribution of 64Cu-PPF. 64Cu-PPF uptake in FR-positive tumors was visible on small-animal PET images with high tumor-to-muscle ratio (8.88 ± 3.60 observed after 24 h. Competitive blocking studies confirmed the FR-mediated tracer uptake by the tumor. The ease of efficient 64Cu-radiolabeling of PPF while retaining its favorable biodistribution, pharmacokinetics and selective tumor uptake, provides a robust strategy to transform tumor-targeted porphyrin-based photosensitizers into PET imaging probes.

  17. Local Electronic Structure of a Single-Layer Porphyrin-Containing Covalent Organic Framework

    KAUST Repository

    Chen, Chen

    2017-12-20

    We have characterized the local electronic structure of a porphyrin-containing single-layer covalent organic framework (COF) exhibiting a square lattice. The COF monolayer was obtained by the deposition of 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMA) and 5,10,15,20-tetrakis(4-aminophenyl) porphyrin (TAPP) onto a Au(111) surface in ultrahigh vacuum followed by annealing to facilitate Schiff-base condensations between monomers. Scanning tunneling spectroscopy (STS) experiments conducted on isolated TAPP precursor molecules and the covalently linked COF networks yield similar transport (HOMO-LUMO) gaps of 1.85 ± 0.05 eV and 1.98 ± 0.04 eV, respectively. The COF orbital energy alignment, however, undergoes a significant downward shift compared to isolated TAPP molecules due to the electron-withdrawing nature of the imine bond formed during COF synthesis. Direct imaging of the COF local density of states (LDOS) via dI/dV mapping reveals that the COF HOMO and LUMO states are localized mainly on the porphyrin cores and that the HOMO displays reduced symmetry. DFT calculations reproduce the imine-induced negative shift in orbital energies and reveal that the origin of the reduced COF wave function symmetry is a saddle-like structure adopted by the porphyrin macrocycle due to its interactions with the Au(111) substrate.

  18. Heterogeneous biomimetic catalysis using iron porphyrin for cyclohexane oxidation promoted by chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Guan, E-mail: huangg66@126.com; Liu, Yao; Cai, Jing Li; Chen, Xiang Feng; Zhao, Shu Kai; Guo, Yong An; Wei, Su Juan; Li, Xu

    2017-04-30

    Graphical abstract: A biomimetic catalyst of iron-tetrakis(4-sulfonatophenyl)porphyrin immobilized on powdered chitosan achieves efficient cyclohexane oxidation with high ketone and alcohol yields. - Highlights: • Fe (TPPS)/pd-CTS is an excellent catalyst for cyclohexane oxidation. • Amino ligation alters the electron cloud density around the iron cation. • Amino coordination likely reduces the activation energy of Fe (TPPS). • The catalyst achieved 22.9 mol% yields of cyclohexanone and cyclohexanol. - Abstract: This study investigates how ligands modulate metalloporphyrin activity with the goal of producing a practical biomimetic catalyst for use in the chemical industry. We immobilized iron porphyrinate [iron-tetrakis-(4-sulfonatophenyl)-porphyrin; Fe(III) (TPPS)] on powdered chitosan (pd-CTS) to form an immobilized catalyst Fe(III) (TPPS)/pd-CTS, which was characterized using modern spectroscopic techniques and used for catalytic oxidation of cyclohexane with O{sub 2}. Amino coordination to iron porphyrin in Fe(III) (TPPS)/pd-CTS altered the electron cloud density around the iron cation, probably by reducing the activation energy of Fe(III) (TPPS) and raising the reactivity of the iron ion catalytic center, thereby improving the catalytic efficiency. One milligram of Fe(III) (TPPS) catalyst can be reused three times for the oxidation reaction to yield an average of 22.9 mol% of cyclohexanone and cyclohexanol.

  19. ALA-based fluorescent diagnosis of malignant oral lesions in the presence of bacterial porphyrin formation

    Science.gov (United States)

    Schleier, P.; Berndt, A.; Zinner, K.; Zenk, W.; Dietel, W.; Pfister, W.

    2006-02-01

    The aminolevulinic acid (5-ALA) -based fluorescence diagnosis has been found to be promising for an early detection and demarcation of superficial oral squamous cell carcinomas (OSCC). This method has previously demonstrated high sensitivity, however this clinical trial showed a specificity of approximately 62 %. This specificity was mainly restricted by tumor detection in the oral cavity in the presence of bacteria. After topical ALA application in the mouth of patients with previously diagnosed OSSC, red fluorescent areas were observed which did not correlate to confirm histological findings. Swabs and plaque samples were taken from 44 patients and cultivated microbiologically. Fluorescence was investigated (OMA-system) from 32 different bacteria strains found naturally in the oral cavity. After ALA incubation, 30 of 32 strains were found to synthesize fluorescent porphyrins, mainly Protoporphyrin IX. Also multiple fluorescent spectra were obtained having peak wavelengths of 636 nm and around 618 nm - 620 nm indicating synthesis of different porphyrins, such as the lipophylic Protoporphyrin IX (PpIX) and hydrophylic porphyrins (water soluble porphyrins, wsp). Of the 32 fluorescent bacterial strains, 18 produced wsp, often in combination with PpIX, and 5 produced solely wsp. These results clarify that ALA-based fluorescence diagnosis without consideration or suppression of bacteria fluorescence may lead to false-positive findings. It is necessary to suppress bacteria fluorescence with suitable antiseptics before starting the procedure. In this study, when specific antiseptic pre-treatment was performed bacterial associated fluorescence was significantly reduced.

  20. Exciplex-exciplex energy transfer and annihilation in solid films of porphyrin-fullerene dyads

    NARCIS (Netherlands)

    Lehtivuori, Heli; Lemmetyinen, Helge; Tkachenko, Nikolai V.

    2006-01-01

    Exciplex-exciplex annihilation was observed for the first time in porphyrin-fullerene molecular films. The films were prepared using Langmuir-Blodgett and drop casting methods. The exciplex-exciplex interactions were studied using femtosecond pump-probe method. The exciplex-exciplex annihilation can