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Sample records for cationic meso-substituted porphyrins

  1. 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.

  2. 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.

  3. Electrochemical behavior of meso-substituted iron porphyrins in alkaline aqueous media

    Science.gov (United States)

    Berezina, N. M.; Bazanov, M. I.; Maksimova, A. A.; Semeikin, A. S.

    2017-12-01

    The effect meso-substitution in iron porphyrin complexes has on their redox behavior in alkaline aqueous solutions is studied via cyclic voltammetry. The voltammetric features of the reduction of iron pyridylporphyrins suggest that the sites of electron transfer lie at the ligand, the metal ion, and the pyridyl moieties. The electron transfer reactions between the different forms of these compounds, including the oxygen reduction reaction they mediate, are outlined to show the sequence and potential ranges in which they occur in alkaline aqueous media. Under our experimental conditions, the iron porphyrins exist as μ-oxo dimmers whose activity for the electrocatalytic reduction of oxygen displays a considerable dependence on the nature of the substitutents and nitrogen isomerization (for pyridylporphyrins) and grows in the order (Fe( ms-Ph)4P)2O, (Fe[ ms-(Py-3)Ph3]P)2O, (Fe[ ms-(Py-4)4]P)2O, and (Fe[ ms-(Py-3)4]P)2O.

  4. Synthesis and characterization of new meso-substituted ...

    Indian Academy of Sciences (India)

    WINTEC

    tems. 10. Their ability to carry out the reactions rather unusual in organic chemistry has been the object of intensive investigations aiming to utilize them as a model compounds for biological systems and as catalysts. 11. Therefore, the synthesis of well defined meso-substituted unsymmetrical porphyrin deriva- tives (A3B) is ...

  5. complexes based on meso-substituted dipyrrins

    Indian Academy of Sciences (India)

    Keywords. Coordination polymers; meso-substituted dipyrrins; heteroleptic; acetylacetonato; ... Room temperature magnetic susceptibility measurements were ... After cooling to ambient tem- perature it ... crystals of 1 were obtained from CH2Cl2/ hexane (1. : 1) solution. .... are air-stable, crystalline solids, soluble in common.

  6. 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.

  7. meso-Substituted bisanthenes as soluble and stable near-infrared dyes

    KAUST Repository

    Li, Jinling

    2010-02-05

    (Chemical Equation Presented) Three meso-substituted bisanthenes, 4-6, were prepared in a short synthetic route from the bisanthenequinone. They exhibit largely improved stability and solubility in comparison to the parent bisanthene. All of these compounds also show near-infrared (NIR) absorption and emission with high to moderate fluorescence quantum yields. Amphoteric redox behavior was observed for 4-6 by cyclic voltammetry, and these compounds can be reversibly oxidized and reduced into respective cationic and anionic species by both electrochemical and chemical processes. In addition, compound 5 adopts a herringbone π-stacking motif in the single crystal. © 2010 American Chemical Society.

  8. 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.

  9. 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

  10. Studies on meso-substituted free-base octamethoxyporphyrins

    Indian Academy of Sciences (India)

    Administrator

    base porphyrin. These data are discussed in terms of electronic structure calculations. Acknowledgement. The authors are thankful to the Council of Scientific and Industrial Research, New Delhi for financial support. Proc. Indian Acad. Sci.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Mitochondria-targeted cationic porphyrin-triphenylamine hybrids for enhanced two-photon photodynamic therapy.

    Science.gov (United States)

    Hammerer, Fabien; Poyer, Florent; Fourmois, Laura; Chen, Su; Garcia, Guillaume; Teulade-Fichou, Marie-Paule; Maillard, Philippe; Mahuteau-Betzer, Florence

    2018-01-01

    The proof of concept for two-photon activated photodynamic therapy has already been achieved for cancer treatment but the efficiency of this approach still heavily relies on the availability of photosensitizers combining high two-photon absorption and biocompatibility. In this line we recently reported on a series of porphyrin-triphenylamine hybrids which exhibit high singlet oxygen production quantum yield as well as high two-photon absorption cross-sections but with a very poor cellular internalization. We present herein new photosensitizers of the same porphyrin-triphenylamine hybrid series but bearing cationic charges which led to strongly enhanced water solubility and thus cellular penetration. In addition the new compounds have been found localized in mitochondria that are preferential target organelles for photodynamic therapy. Altogether the strongly improved properties of the new series combined with their specific mitochondrial localization lead to a significantly enhanced two-photon activated photodynamic therapy efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. [Study on the aggregation behavior of cationic porphyrins and their interaction with ctDNA].

    Science.gov (United States)

    Ma, Hong-Min; Chen, Xin; Sun, Shu-Ting; Zhang, Li-Na; Wu, Dan; Zhu, Pei-Hua; Li, Yan; Du, Bin; Wei, Qin

    2009-02-01

    Interest in the interaction between cationic porphyrins, particularly derivatives of meso-tetra(N-methylpyridinium-4-yl) porphyrin(TMPyP), and DNA abounds because they are versatile DNA-binding agents that could find application in photodynamic therapy, cancer detection, artificial nucleases, virus inhibition and so on. The interaction of two water-soluble cationic porphyrins, meso-tetrakis(4-N, N, N-trimethylanilinium) porphyrin (TMAP) and 5-phenyl-10,15,20-tris[4-(N-methyl) pyridinium]porphyrin (TriMPyP), with calf thymus DNA (ctDNA) was studied by UV-Vis absorption spectroscopy, fluorescence spectroscopy and resonance light scattering technique. TriMPyP forms aggregate in water due to the molecular asymmetry while TMAP exists as monomers. At lower concentrations of ctDNA (R > 1, R = c(TMAP)/c(DNA) base pair), the interaction of TMAP with DNA leads to significant hypochromicity and bathochromic shift of absorption spectra. And the fluorescence of TMAP was quenched while it showed enhanced resonance light scattering signals. But the extent of enhancement of resonance light scattering signals is very small, so the aggregate of TMAP is not very high. These observations indicate the self-stacking of TMAP along the DNA surface. At higher concentrations of ctDNA (R TMAP association with DNA is via outside binding which is accompanied with hyperchromic effect and fluorescence enhancement while the resonance light scattering signals is reduced. DNA addition decreases the fluorescence intensity of TriMPyP and it shifts the peak to the higher wavelengths (red shift). The interaction with DNA promotes the aggregation of TriMPyP and no simple outside binding is observed even at higher concentrations of ctDNA. The steric effect of molecular distortion constrains the intercalation or further binding to DNA. The effect of ionic strength on the interaction was investigated at two DNA concentrations, 1.2 and 24.0 micromol x L(-1), for TMAP. The Interactions of both porphyrins

  18. Spectroscopic studies on the interaction of a water-soluble cationic porphyrin with proteins

    Science.gov (United States)

    Ma, Hong-Min; Chen, Xin; Zhang, Nuo; Han, Yan-Yan; Wu, Dan; Du, Bin; Wei, Qin

    2009-04-01

    The interaction of a water-soluble cationic porphyrin, meso-tetrakis (4- N, N, N-trimethylanilinium) porphyrin (TMAP), with two proteins, bovine serum albumin (BSA) and human serum albumin (HSA), was studied by UV-vis absorption spectroscopy, fluorescence spectroscopy, fluorescence anisotropy and synchronous fluorescence spectroscopy at neutral aqueous solutions. Free base TMAP bound to proteins as monomers and no aggregation was observed. The binding of TMAP quenched the fluorescence of the protein. On the contrary, the fluorescence of TMAP was enhanced and the fluorescence anisotropy increased due to the binding. The direct static binding mechanism could account for the quenching by TMAP and the binding constants were calculated. TMAP showed a higher quenching efficiency and binding constant of HSA than BSA. The binding of TMAP had no obvious effect on the molecular conformation of the protein. There was only one binding site for TMAP and it was located on the surface of the protein molecule. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the proteins.

  19. Mechanistic insight of the photodynamic effect induced by tri- and tetra-cationic porphyrins on Candida albicans cells.

    Science.gov (United States)

    Cormick, M Paula; Quiroga, Ezequiel D; Bertolotti, Sonia G; Alvarez, M Gabriela; Durantini, Edgardo N

    2011-10-01

    The photodynamic mechanism of action induced 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 on Candida albicans cells. These cationic porphyrins are effective photosensitizers, producing a ~5 log decrease of cell survival when the cultures are incubated with 5 μM photosensitizer and irradiated for 30 min with visible light. Studies under anoxic conditions indicated that oxygen is necessary for the mechanism of action of photodynamic inactivation of this yeast. Furthermore, photoinactivation of C. albicans cells was negligible in the presence of 100 mM azide ion, whereas the photocytotoxicity induced by these porphyrins increased in D(2)O. In contrast, the addition of 100 mM mannitol produced a negligible effect on the cellular phototoxicity. On the other hand, in vitro direct observation of singlet molecular oxygen, O(2)((1)Δ(g)) phosphorescence at 1270 nm was analyzed using C. albicans in D(2)O. A shorter lifetime of O(2)((1)Δ(g)) was found in yeast cellular suspensions. These cationic porphyrins bind strongly to C. albicans cells and the O(2)((1)Δ(g)) generated inside the cells is rapidly quenched by the biomolecules of the cellular microenvironment. Therefore, the results indicate that these cationic porphyrins appear to act as photosensitizers mainly via the intermediacy of O(2)((1)Δ(g)). This journal is © The Royal Society of Chemistry and Owner Societies 2011

  20. Effects of divalent cations, EDTA and chitosan on the uptake and photoinactivation of Escherichia coli mediated by cationic and anionic porphyrins.

    Science.gov (United States)

    Gsponer, Natalia S; Spesia, Mariana B; Durantini, Edgardo N

    2015-03-01

    The effect of divalent cations, EDTA and chitosan (CS) on the uptake and photoinactivation of Escherichia coli produced by 5,10,15,20-tetrakis(4-N,N,N-trimethylammoniumphenyl)porphyrin (TMAP(4+)), 5,10-di(4-methylphenyl)-15,20-di(4-N,N,N-trimethylammoniumphenyl)porphyrin (MPAP(2+)) and 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS(4-)) were examined under different conditions. These porphyrins were rapidly bound to E. coli cells (TMAP(4+), MPAP(2+) and TPPS(4-), respectively. The addition of Ca(2+) or Mg(2+) to the cultures enhanced the uptake of MPAP(2+) and TPPS(4-) by cells. In contrast, the amount of TMAP(4+) bound to cells was decreased. The presence of EDTA produced an increase in the uptake of porphyrins by cells, while CS mainly enhanced the amount of TPPS(4-) bound to E. coli. The photoinactivation of E. coli cells mediated by TMAP(4+) was highly effective even at low concentration (1μM) and short irradiation period (5min). However, a reduction in the phototoxicity was found for TMAP(4+) in presence of Ca(2+) and Mg(2+). In contrast, the phototoxic activity mediated by MPAP(2+) and TPPS(4-) was increased. Addition of EDTA did not show effect on the photoinactivation induced by cationic porphyrins, while a small enhance was found for TPPS(4-). Moreover, inactivation of E. coli cells was achieved in the presence CS. This cationic polymer was antimicrobial by itself in the dark. Using a slightly toxic CS concentration, the phototoxic activity induced by TMAP(4+) was diminished. This effect was mainly observed at lower concentration of TMAP(4+) (0.5-1μM). In contrast, an increase in E. coli photoinactivation was obtained for MPAP(2+) and TPPS(4-) in presence of CS. Thus, this natural polymeric destabilizer agent mainly benefited the photoinactivation mediated by TPPS(4-). Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Room temperature Zinc-metallation of cationic porphyrin at graphene surface and enhanced photoelectrocatalytic activity

    Science.gov (United States)

    Zeng, Rongjin; Chen, Guoliang; Xiong, Chungang; Li, Gengxian; Zheng, Yinzhi; Chen, Jian; Long, Yunfei; Chen, Shu

    2018-03-01

    A stable zincporphyrin functionalized graphene nanocomposite was prepared by using positively charged cationic porphyrin (5,10,15,20-tetra(4-propyl pyridinio) porphyrin, TPPyP) and successive reduced graphene oxide (rGO) with tuned negative charge. The nanocomposite preparation was accompanied first by distinct electrostatic interactions and π-π stacking between TPPyP and rGO, and followed by fast Zinc-metallation at room temperature. In contrast to free TPPyP with Zn2+, the incorporation reaction is very slow at room temperature and heating or reflux conditions are required to increase the metallation rate. While at the surface of rGO nanosheet, the Zinc-metallation of TPPyP was greatly accelerated to 30 min at 25 °C in aqueous solution. The interaction process and composites formation were fully revealed by significant variations in UV-vis absorption spectra, X-ray photoelectron spectra (XPS) measurements, atomic force microscope (AFM) images, and fluorescence spectra. Furthermore, photoelectrochemical activity of resultant rGO/TPPyP-Zn nanocomposites was evaluated under visible-light irradiation, and enhancement of the photoelectrocatalytic reduction of CO2 was achieved.

  2. Remarkable fluorescence enhancement versus complex formation of cationic porphyrins on the surface of ZnO nanoparticles

    KAUST Repository

    Aly, Shawkat Mohammede

    2014-06-12

    Fluorescence enhancement of organic fluorophores shows tremendous potential to improve image contrast in fluorescence-based bioimaging. Here, we present an experimental study of the interaction of two cationic porphyrins, meso-tetrakis(1-methylpyridinium-4-yl)porphyrin chloride (TMPyP) and meso-tetrakis(4-N,N,N-trimethylanilinium)porphyrin chloride (TMAP), with cationic surfactant-stabilized zinc oxide nanoparticles (ZnO NPs) based on several steady-state and time-resolved techniques. We show the first experimental measurements demonstrating a clear transition from pronounced fluorescence enhancement to charge transfer (CT) complex formation by simply changing the nature and location of the positive charge of the meso substituent of the cationic porphyrins. For TMPyP, we observe a sixfold increase in the fluorescence intensity of TMPyP upon addition of ZnO NPs. Our experimental results indicate that the electrostatic binding of TMPyP with the surface of ZnO NPs increases the symmetry of the porphyrin macrocycle. This electronic communication hinders the rotational relaxation of the meso unit and/or decreases the intramolecular CT character between the cavity and the meso substituent of the porphyrin, resulting in the enhancement of the intensity of the fluorescence. For TMAP, on the other hand, the different type and nature of the positive charge resulting in the development of the CT band arise from the interaction with the surface of ZnO NPs. This observation is confirmed by the femtosecond transient absorption spectroscopy, which provides clear spectroscopic signatures of photoinduced electron transfer from TMAP to ZnO NPs. © 2014 American Chemical Society.

  3. 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

  4. Charge Carrier Dynamics and pH Effect on Optical Properties of Anionic and Cationic Porphyrin-Graphene Oxide Composites

    Science.gov (United States)

    Bajjou, O.; Bakour, A.; Khenfouch, M.; Baitoul, M.; Mothudi, B.; Maaza, M.; Faulques, E.

    2018-02-01

    Composites of graphene oxide (GO) functionalized with Sn(V) tetrakis (4-pyridyl)porphyrin (SnTPyP2+) and meso-tetrakis(4-phenylsulfonic acid)porphyrin (H4TPPS4 2- ) were prepared at different pH values.Successful synthesis of water-soluble stable suspension of GO-SnTPyP2+ and GO-H4TPPS4 2-was confirmed using various spectroscopic techniques, including scanning electronic microscopy (SEM), Raman spectroscopy, and ultraviolet-visible (UV-Vis) absorption. Variation of the pH was found to strongly influence the optical properties of the GO-SnTPyP2+ and GO-H4TPPS4 2-composites, as demonstrated by the UV-Vis absorption results. Steady-state photoluminescence (PL) and time-resolved PL (TRPL) results for both composites showed PL quenching and decrease in the exciton mean lifetime, suggesting strong excited-state interactions between the different components. Moreover, charge carrier dynamics study revealed that insertion of GO into both porphyrin derivatives led to faster mean lifetime for excitons with a slight advantage in the case of the cationic porphyrin-GO composite, making it a better choice for charge separation applications thanks to the higher efficiency of charge/energy transfer interactions.

  5. 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.

  6. 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.

  7. 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.

  8. Water Soluble Cationic Porphyrin Sensor for Detection of Hg2+, Pb2+, Cd2+, and Cu2+

    Directory of Open Access Journals (Sweden)

    Matibur Zamadar

    2016-01-01

    Full Text Available Here we report the sensing properties of the aqueous solution of meso-tetra(N-methyl-4-pyridylporphine tetrachloride (1 for simultaneous detection of toxic metal ions by using UV-vis spectroscopy. Cationic porphyrin 1 displayed different electronic absorptions in UV-vis region upon interacting with Hg2+, Pb2+, Cd2+, and Cu2+ ions in neutral water solution at room temperature. Quite interestingly, the porphyrin 1 showed that it can function as a single optical chemical sensor and/or metal ion receptor capable of detecting two or more toxic metal ions, particularly Hg2+, Pb2+, and Cd2+ ions coexisting in a water sample. Porphyrin 1 in an aqueous solution provides a unique UV-vis sensing system for the determination of Cd2+ in the presence of larger metal ions such as Hg2+, or Pb2+. Finally, the examination of the sensing properties of 1 demonstrated that it can operate as a Cu2+ ion selective sensor via metal displacement from the 1-Hg2+, 1-Pb2+, and 1-Cd2+.

  9. Molecular-structure control of ultrafast electron injection at cationic porphyrin-CdTe quantum dot interfaces

    KAUST Repository

    Aly, Shawkat Mohammede

    2015-03-05

    Charge transfer (CT) at donor (D)/acceptor (A) interfaces is central to the functioning of photovoltaic and light-emitting devices. Understanding and controlling this process on the molecular level has been proven to be crucial for optimizing the performance of many energy-challenge relevant devices. Here, we report the experimental observations of controlled on/off ultrafast electron transfer (ET) at cationic porphyrin-CdTe quantum dot (QD) interfaces using femto- and nanosecond broad-band transient absorption (TA) spectroscopy. The time-resolved data demonstrate how one can turn on/off the electron injection from porphyrin to the CdTe QDs. With careful control of the molecular structure, we are able to tune the electron injection at the porphyrin-CdTe QD interface from zero to very efficient and ultrafast. In addition, our data demonstrate that the ET process occurs within our temporal resolution of 120 fs, which is one of the fastest times recorded for organic photovoltaics. © 2015 American Chemical Society.

  10. Adsorption characteristics of a cationic porphyrin on nanoclay at various pH.

    Science.gov (United States)

    Rice, Zachary; Bergkvist, Magnus

    2009-07-15

    Natural and synthetic porphyrin derivatives offer a range of applications including enzymatic catalysis, photosensitizers for light harvesting and chemical reactions, and molecular electronics. They exhibit unique optical spectra dominated by the presence of Soret and Q-band structures whose position and shape offer a straightforward method to characterize porphyrins in various surroundings. In many applications it is often beneficial to have porphyrins adsorbed onto a solid matrix. Applications of porphyrin-clay complexes extend to numerous biological applications including pharmaceutical drug delivery, cosmetics, and agricultural applications and thus a full understanding of porphyrin-clay surface interactions are essential. Here we investigated the adsorption behavior of meso-tetra(4-N,N,N-trimethylanilinium) porphine (TMAP) onto sodium containing, natural montmorillonite clay (Cloisite Na(+)) in characteristic biological buffers over a range of pHs (approximately 2-9). Spectroscopic analyses show a linear absorption response at acidic and basic pHs but a slight deviation at intermediate pHs. Absorption spectra for TMAP on clay showed distinct red shifts of the Soret and Q-bands compared to free TMAP for all buffer conditions indicating core pi-electron delocalization into the substituent rings. At intermediate pHs, a gradual transition between protonated/deprotonated states were seen, presumably due to higher H(+) concentration at the surface than in bulk. Results indicate TMAP adsorption to clay occurs in a monolayer fashion at low/high pH while slightly acidic/neutral pH possibly rearrange on the surface and/or form aggregates. AFM images of clay saturated with TMAP are reported and show single isolated clay sheets without aggregation, similar to clay without TMAP.

  11. Effect of zinc insertion and hydrophobicity on the membrane interactions and PDT activity of porphyrin photosensitizers.

    Science.gov (United States)

    Pavani, Christiane; Uchoa, Adjaci F; Oliveira, Carla S; Iamamoto, Yassuko; Baptista, Maurício S

    2009-02-01

    A series of photosensitizers (PS), which are meso-substituted tetra-cationic porphyrins, was synthesized in order to study the role of amphiphilicity and zinc insertion in photodynamic therapy (PDT) efficacy. Several properties of the PS were evaluated and compared within the series including photophysical properties (absorption spectra, fluorescence quantum yield Phif, and singlet oxygen quantum yield PhiDelta), uptake by vesicles, mitochondria and HeLa cells, dark and phototoxicity in HeLa cells. The photophysical properties of all compounds are quite similar (Phifporphyrin ring result in higher vesicle and cell uptake. Binding in mitochondria is dependent on the PS lipophilicity and on the electrochemical membrane potential, i.e., in uncoupled mitochondria PS binding decreases by up to 53%. The porphyrin substituted with octyl groups (TC8PyP) is the compound that is most enriched in mitochondria, and its zinc derivative (ZnTC8PyP) has the highest global uptake. The stronger membrane interaction of the zinc-substituted porphyrins is attributed to a complexing effect with phosphate groups of the phospholipids. Zinc insertion was also shown to decrease the interaction with isolated mitochondria and with the mitochondria of HeLa cells, an effect that has been explained by the particular characteristics of the mitochondrial internal membrane. Phototoxicity was shown to increase proportionally with membrane binding efficiency, which is attributed to favorable membrane interactions which allow more efficient membrane photooxidation. For this series of compounds, photodynamic efficiency is directly proportional to the membrane binding and cell uptake, but it is not totally related to mitochondrial targeting.

  12. 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.

  13. meso-Substituted bisanthenes as soluble and stable near-infrared dyes

    KAUST Repository

    Li, Jinling; Zhang, Kai; Zhang, Xiaojie; Huang, Kuo-Wei; Chi, Chunyan; Wu, Jishan

    2010-01-01

    into respective cationic and anionic species by both electrochemical and chemical processes. In addition, compound 5 adopts a herringbone π-stacking motif in the single crystal. © 2010 American Chemical Society.

  14. A new cationic porphyrin derivative (TMPipEOPP with large side arm substituents: a highly selective G-quadruplex optical probe.

    Directory of Open Access Journals (Sweden)

    Li-Na Zhu

    Full Text Available The discovery of uncommon DNA structures and speculation about their potential functions in genes has brought attention to specific DNA structure recognition. G-quadruplexes are four-stranded nucleic acid structures formed by G-rich DNA (or RNA sequences. G-rich sequences with a high potential to form G-quadruplexes have been found in many important genomic regions. Porphyrin derivatives with cationic side arm substituents are important G-quadruplex-binding ligands. For example, 5,10,15,20-Tetrakis(N-methylpyridinium-4-yl-21H,23H-porphyrin (TMPyP4, interacts strongly with G-quadruplexes, but has poor selectivity for G-quadruplex versus duplex DNA. To increase the G-quadruplex recognition specificity, a new cationic porphyrin derivative, 5,10,15,20-tetra-{4-[2-(1-methyl-1-piperidinylethoxy]phenyl} porphyrin (TMPipEOPP, with large side arm substituents was synthesized, and the interactions between TMPipEOPP and different DNA structures were compared. The results show that G-quadruplexes cause large changes in the UV-Vis absorption and fluorescence spectra of TMPipEOPP, but duplex and single-stranded DNAs do not, indicating that TMPipEOPP can be developed as a highly specific optical probe for discriminating G-quadruplex from duplex and single-stranded DNA. Visual discrimination is also possible. Job plot and Scatchard analysis suggest that a complicated binding interaction occurs between TMPipEOPP and G-quadruplexes. At a low [G-quadruplex]/[TMPipEOPP] ratio, one G-quadruplex binds two TMPipEOPP molecules by end-stacking and outside binding modes. At a high [G-quadruplex]/[TMPipEOPP] ratio, two G-quadruplexes bind to one TMPipEOPP molecule in a sandwich-like end-stacking mode.

  15. A new cationic porphyrin derivative (TMPipEOPP) with large side arm substituents: a highly selective G-quadruplex optical probe.

    Science.gov (United States)

    Zhu, Li-Na; Zhao, Shu-Juan; Wu, Bin; Li, Xiao-Zeng; Kong, De-Ming

    2012-01-01

    The discovery of uncommon DNA structures and speculation about their potential functions in genes has brought attention to specific DNA structure recognition. G-quadruplexes are four-stranded nucleic acid structures formed by G-rich DNA (or RNA) sequences. G-rich sequences with a high potential to form G-quadruplexes have been found in many important genomic regions. Porphyrin derivatives with cationic side arm substituents are important G-quadruplex-binding ligands. For example, 5,10,15,20-Tetrakis(N-methylpyridinium-4-yl)-21H,23H-porphyrin (TMPyP4), interacts strongly with G-quadruplexes, but has poor selectivity for G-quadruplex versus duplex DNA. To increase the G-quadruplex recognition specificity, a new cationic porphyrin derivative, 5,10,15,20-tetra-{4-[2-(1-methyl-1-piperidinyl)ethoxy]phenyl} porphyrin (TMPipEOPP), with large side arm substituents was synthesized, and the interactions between TMPipEOPP and different DNA structures were compared. The results show that G-quadruplexes cause large changes in the UV-Vis absorption and fluorescence spectra of TMPipEOPP, but duplex and single-stranded DNAs do not, indicating that TMPipEOPP can be developed as a highly specific optical probe for discriminating G-quadruplex from duplex and single-stranded DNA. Visual discrimination is also possible. Job plot and Scatchard analysis suggest that a complicated binding interaction occurs between TMPipEOPP and G-quadruplexes. At a low [G-quadruplex]/[TMPipEOPP] ratio, one G-quadruplex binds two TMPipEOPP molecules by end-stacking and outside binding modes. At a high [G-quadruplex]/[TMPipEOPP] ratio, two G-quadruplexes bind to one TMPipEOPP molecule in a sandwich-like end-stacking mode.

  16. An efficient solvent-free synthesis of meso-substituted dipyrromethanes using SnCl2•2H2O catalysis

    Directory of Open Access Journals (Sweden)

    Kabeer Ahmed Shaikh

    2012-07-01

    Full Text Available Highly rapid and simple methodology has been developed for the quantitative synthesis of meso-substituted dipyrromethanes from lowest pyrrole/aldehyde ratio. The method was carried out by using SnCl2•2H2O as a catalyst under solvent free condition. The method is environmentally friendly, easy to workup, and gives excellent yield of the products.

  17. Spectroscopic and Kinetic Characterization of Peroxidase-Like π-Cation Radical Pinch-Porphyrin-Iron(III Reaction Intermediate Models of Peroxidase Enzymes

    Directory of Open Access Journals (Sweden)

    Samuel Hernández Anzaldo

    2016-06-01

    Full Text Available The spectroscopic and kinetic characterization of two intermediates from the H2O2 oxidation of three dimethyl ester [(proto, (meso, (deuteroporphyrinato (picdien]Fe(III complexes ([FePPPic], [FeMPPic] and [FeDPPic], respectively pinch-porphyrin peroxidase enzyme models, with s = 5/2 and 3/2 Fe(III quantum mixed spin (qms ground states is described herein. The kinetic study by UV/Vis at λmax = 465 nm showed two different types of kinetics during the oxidation process in the guaiacol test for peroxidases (1–3 + guaiacol + H2O2 → oxidation guaiacol products. The first intermediate was observed during the first 24 s of the reaction. When the reaction conditions were changed to higher concentration of pinch-porphyrins and hydrogen peroxide only one type of kinetics was observed. Next, the reaction was performed only between pinch-porphyrins-Fe(III and H2O2, resulting in only two types of kinetics that were developed during the first 0–4 s. After this time a self-oxidation process was observed. Our hypotheses state that the formation of the π-cation radicals, reaction intermediates of the pinch-porphyrin-Fe(III family with the ligand picdien [N,N’-bis-pyridin-2-ylmethyl-propane-1,3-diamine], occurred with unique kinetics that are different from the overall process and was involved in the oxidation pathway. UV-Vis, 1H-NMR and ESR spectra confirmed the formation of such intermediates. The results in this paper highlight the link between different spectroscopic techniques that positively depict the kinetic traits of artificial compounds with enzyme-like activity.

  18. The impact of Au doping on the charge carrier dynamics at the interfaces between cationic porphyrin and silver nanoclusters

    KAUST Repository

    Almansaf, Abdulkhaleq A.

    2017-02-04

    We explore the impact of Au doping on the charge transfer dynamics between the positively charged porphyrin (TMPyP) and negatively charged silver nanoclusters (Ag29 NCs). Our transient absorption (TA) spectroscopic results demonstrate that the interfacial charge transfer, the intersystem crossing and the triplet state lifetime of porphyrin can be tuned by the doping of Au atoms in Ag29 NCs. Additionally, we found that the electrostatic interaction between the negative charge of the cluster and the positive charge on the TMPyP is the driving force that brings them close to each other for complex formation and subsequently facilitates the transfer process.

  19. The impact of Au doping on the charge carrier dynamics at the interfaces between cationic porphyrin and silver nanoclusters

    KAUST Repository

    Almansaf, Abdulkhaleq A.; Parida, Manas R.; Besong, Tabot M.D.; Maity, Partha; Bootharaju, Megalamane Siddaramappa; Bakr, Osman; Mohammed, Omar F.

    2017-01-01

    We explore the impact of Au doping on the charge transfer dynamics between the positively charged porphyrin (TMPyP) and negatively charged silver nanoclusters (Ag29 NCs). Our transient absorption (TA) spectroscopic results demonstrate that the interfacial charge transfer, the intersystem crossing and the triplet state lifetime of porphyrin can be tuned by the doping of Au atoms in Ag29 NCs. Additionally, we found that the electrostatic interaction between the negative charge of the cluster and the positive charge on the TMPyP is the driving force that brings them close to each other for complex formation and subsequently facilitates the transfer process.

  20. Heterometallic Pd(II)-Ni(II) complexes with meso-substituted dibenzotetraaza[14]annulene: double C-H bond activation and formation of a rectangular tetradibenzotetraaza[14]annulene.

    Science.gov (United States)

    Khaledi, Hamid; Olmstead, Marilyn M; Fukuda, Takamitsu; Ali, Hapipah Mohd

    2014-11-03

    Three isomeric 2[Pd(II)-Ni(II)] metal complexes, derived from indoleninyl meso-substituted dibenzotetraaza[14]annulene, were synthesized. The resulting dimers feature Ni···Ni or, alternatively, Ni···π interactions in staggered or slipped cofacial structures. A remarkable insertion of palladium into two different C-H bonds yielded a 4[Pd(II)-Ni(II)] rectangular complex with dimensions of 8.73 × 10.38 Å.

  1. 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

  2. Remarkable fluorescence enhancement versus complex formation of cationic porphyrins on the surface of ZnO nanoparticles

    KAUST Repository

    Aly, Shawkat Mohammede; Eita, Mohamed Samir; Khan, Jafar Iqbal; Alarousu, Erkki; Mohammed, Omar F.

    2014-01-01

    the first experimental measurements demonstrating a clear transition from pronounced fluorescence enhancement to charge transfer (CT) complex formation by simply changing the nature and location of the positive charge of the meso substituent of the cationic

  3. 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.

  4. Inclusion of 5-[4-(1-dodecanoylpyridinium)]-10,15,20-triphenylporphine in supramolecular aggregates of cationic amphiphilic cyclodextrins: physicochemical characterization of the complexes and strengthening of the antimicrobial photosensitizing activity.

    Science.gov (United States)

    Ferro, Stefania; Jori, Giulio; Sortino, Salvatore; Stancanelli, Rosanna; Nikolov, Peter; Tognon, Giuseppe; Ricchelli, Fernanda; Mazzaglia, Antonino

    2009-09-14

    Recent findings suggest that visible light-promoted photooxidative processes mediated by sensitizers of appropriate chemical structure could represent a useful tool for properly addressing the problem of the increasing occurrence of infectious diseases caused by multiantibiotic-resistant microbial pathogens. The monocationic meso-substituted porphyrin 5-[4-(1-dodecanoylpyridinium)]-10,15,20-triphenyl-porphine (TDPyP) complexed into supramolecular aggregates of cationic amphiphilic beta-cyclodextrin (SC(6)NH(2)) (mean diameter = 20 nm) appeared to be endowed with favorable properties to act as a photosensitizing agent, including a very high quantum yield (Phi(Delta) = 0.90) for the generation of the highly reactive oxygen species, singlet oxygen ((1)O(2)). Although the yield of (1)O(2) generation was comparable to that obtained after TDPyP incorporation into cationic unilamellar liposomes of N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP) SC(6)NH(2)-bound TDPyP was more active than DOTAP-bound TDPyP in photosensitizing the inactivation of the Gram-positive methicillin-resistant bacterium Staphylococcus aureus (MRSA). At variance with DOTAP-bound TDPyP, photoactivated SC(6)NH(2)-bound TDPyP was efficient also in photokilling Gram-negative bacterial pathogens, such as Escherichia coli . These observations are in agreement with the well-known photobactericidal effect of positively charged porphyrin derivatives, which can be markedly enhanced after incorporation into carriers with multiple positive charges. In addition, transmission electron microscopy studies revealed that potentiation of the TDPyP-mediated photobactericidal effect by incorporation into SC(6)NH(2) is a consequence of the carrier's ability to promote an efficient crossing of the very tightly organized three-dimensional architecture of the bacterial outer wall by the embedded porphyrin so that a prompt interaction between the short-lived photogenerated (1)O(2) and the nearby

  5. Factors affecting hydrogen-tunneling contribution in hydroxylation reactions promoted by oxoiron(IV) porphyrin π-cation radical complexes.

    Science.gov (United States)

    Cong, Zhiqi; Kinemuchi, Haruki; Kurahashi, Takuya; Fujii, Hiroshi

    2014-10-06

    Hydrogen atom transfer with a tunneling effect (H-tunneling) has been proposed to be involved in aliphatic hydroxylation reactions catalyzed by cytochrome P450 and synthetic heme complexes as a result of the observation of large hydrogen/deuterium kinetic isotope effects (KIEs). In the present work, we investigate the factors controlling the H-tunneling contribution to the H-transfer process in hydroxylation reaction by examining the kinetics of hydroxylation reactions at the benzylic positions of xanthene and 1,2,3,4-tetrahydronaphthalene by oxoiron(IV) 5,10,15,20-tetramesitylporphyrin π-cation radical complexes ((TMP(+•))Fe(IV)O(L)) under single-turnover conditions. The Arrhenius plots for these hydroxylation reactions of H-isotopomers have upwardly concave profiles. The Arrhenius plots of D-isotopomers, clear isosbestic points, and product analysis rule out the participation of thermally dependent other reaction processes in the concave profiles. These results provide evidence for the involvement of H-tunneling in the rate-limiting H-transfer process. These profiles are simulated using an equation derived from Bell's tunneling model. The temperature dependence of the KIE values (k(H)/k(D)) determined for these reactions indicates that the KIE value increases as the reaction temperature becomes lower, the bond dissociation energy (BDE) of the C-H bond of a substrate becomes higher, and the reactivity of (TMP(+•))Fe(IV)O(L) decreases. In addition, we found correlation of the slope of the ln(k(H)/k(D)) - 1/T plot and the bond strengths of the Fe═O bond of (TMP(+•))Fe(IV)O(L) estimated from resonance Raman spectroscopy. These observations indicate that these factors modulate the extent of the H-tunneling contribution by modulating the ratio of the height and thickness of the reaction barrier.

  6. Theoretical investigation of the charge-transfer properties in different meso-linked zinc porphyrins for highly efficient dye-sensitized solar cells.

    Science.gov (United States)

    Namuangruk, Supawadee; Sirithip, Kanokkorn; Rattanatwan, Rattanawelee; Keawin, Tinnagon; Kungwan, Nawee; Sudyodsuk, Taweesak; Promarak, Vinich; Surakhot, Yaowarat; Jungsuttiwong, Siriporn

    2014-06-28

    The charge transfer effect of different meso-substituted linkages on porphyrin analogue 1 (A1, B1 and C1) was theoretically investigated using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The calculated geometry parameters and natural bond orbital analysis reveal that the twisted conformation between porphyrin macrocycle and meso-substituted linkages leads to blocking of the conjugation of the conjugated backbone, and the frontier molecular orbital plot shows that the intramolecular charge transfer of A1, B1 and C1 hardly takes place. In an attempt to improve the photoinduced intramolecular charge transfer ability of the meso-linked zinc porphyrin sensitizer, a strong electron-withdrawing group (CN) was introduced into the anchoring group of analogue 1 forming analogue 2 (A2, B2 and C2). The density difference plot of A2, B2 and C2 shows that the charge transfer properties dramatically improved. The electron injection process has been performed using TDDFT; the direct charge-transfer transition in the A2-(TiO2)38 interacting system takes place; our results strongly indicated that introducing electron-withdrawing groups into the acceptor part of porphyrin dyes can fine-tune the effective conjugation length of the π-spacer and improve intramolecular charge transfer properties, consequently inducing the electron injection process from the anchoring group of the porphyrin dye to the (TiO2)38 surface which may improve the conversion efficiency of the DSSCs. Our calculated results can provide valuable information and a promising outlook for computation-aided sensitizer design with anticipated good properties in further experimental synthesis.

  7. 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.

  8. 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.

  9. 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.

  10. Nanometrological porphyrins

    International Nuclear Information System (INIS)

    Safar, G A M; Idemori, Y M; CarvalhoDa-Silva, D; Rebouças, J S; Mazzoni, M S C; Righi, A

    2012-01-01

    A new cationic silver N-alkylpyridylporphyrin complex is able to ‘sense’ nanometric conductive particles with a diameter below 10 nm. The luminescence of the molecule changes its maximum from red to blue when it embraces a conductive (metallic or semiconducting) nanoparticle. The change is explained on the basis of a charge transfer between the molecule and the conductive nanoparticle along with a geometrical distortion of the porphyric ring and pyridinium substituents. This new molecule could be used to sense nanoparticle contamination in the environment, in the industry of heterogeneous catalysis and many other branches of nanometrological applications. (paper)

  11. 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.

  12. 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.

  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. 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. 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 ...

  16. 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.

  17. 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...

  18. 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

  19. 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.

  20. 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.

  1. Reversible formation of high-valent-iron-oxo-porphyrin intermediate in heme-based catalysis: revisiting the kinetic model for horseradish peroxidase.

    NARCIS (Netherlands)

    Haandel, van M.J.H.; Primus, J.L.; Teunis, C.; Boersma, M.G.; Osman, A.M.; Veeger, C.; Rietjens, I.M.C.M.

    1998-01-01

    Many heme-containing biocatalysts exert their catalytic action through the initial formation of so-called high-valent-iron-oxo porphyrin intermediates. For horseradish peroxidase the initial intermediate formed has been identified as a high-valent-iron-oxo porphyrin π-radical cation, called compound

  2. 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.

  3. 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).

  4. 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)

  5. 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%.

  6. 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.

  7. 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.

  8. 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.

  9. Characterization of cationic glycoporphyrins by electrospray tandem mass spectrometry.

    Science.gov (United States)

    Silva, Eduarda M P; Serra, Vanda Vaz; Ribeiro, Anderson O; Tomé, João P C; Domingues, Pedro; Faustino, M Amparo F; Neves, M Graça P M S; Tomé, Augusto C; Cavaleiro, José A S; Ferrer-Correia, António J; Iamamoto, Yassuko; Domingues, M Rosário M

    2006-01-01

    Novel cationic porphyrin derivatives having a galactose or a bis(isopropylidene)galactose unit linked directly to a pyridine or to an aminophenyl group were characterized by electrospray tandem mass spectrometry (ESI-MS/MS). The electrospray mass spectra (ESI-MS) show the M(+) ions, since these porphyrins are already monocharged in solution. The fragmentation of these ions under ESI-MS/MS conditions was studied and it was found that elimination of the sugar residue as a radical (-163 or -243 Da) is a common fragmentation pathway. Loss of the sugar unit as a neutral fragment (-162 or -242 Da) and cross-ring fragmentations typical of glyco-derivatives are also observed for the pyridinium glycoporphyrins, but they are absent in the case of ammonium glycoporphyrins. The cationic beta-pyridiniumvinyl porphyrins show an atypical fragmentation due to the cleavage of the C(5)-C(6) bond of the sugar unit. Overall, the different patterns of fragmentation observed in the ESI-MS/MS spectra of the sugar pyridinium porphyrins and of the sugar ammonium phenyl porphyrins can give important information about the type of spacer between the porphyrin and the sugar unit. Copyright (c) 2006 John Wiley & Sons, Ltd.

  10. 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.

  11. 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.

  12. Actinide cation-cation complexes

    International Nuclear Information System (INIS)

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO 2 + ) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO 2 + ; therefore, cation-cation complexes indicate something unique about AnO 2 + cations compared to actinide cations in general. The first cation-cation complex, NpO 2 + ·UO 2 2+ , was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO 2 + species, the cation-cation complexes of NpO 2 + have been studied most extensively while the other actinides have not. The only PuO 2 + cation-cation complexes that have been studied are with Fe 3+ and Cr 3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO 2 + ·UO 2 2+ , NpO 2 + ·Th 4+ , PuO 2 + ·UO 2 2+ , and PuO 2 + ·Th 4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M -1

  13. 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.

  14. Obstruction of photoinduced electron transfer from excited porphyrin to graphene oxide: a fluorescence turn-on sensing platform for iron (III ions.

    Directory of Open Access Journals (Sweden)

    Zhong De Liu

    Full Text Available A comparative research of the assembly of different porphyrin molecules on graphene oxide (GO and reduced graphene oxide (RGO was carried out, respectively. Despite the cationic porphyrin molecules can be assembled onto the surfaces of graphene sheets, including GO and RGO, to form complexes through electrostatic and π-π stacking interactions, the more obvious fluorescence quenching and the larger red-shift of the Soret band of porphyrin molecule in RGO-bound states were observed than those in GO-bound states, due to the difference of molecular flattening in degree. Further, more interesting finding was that the complexes formed between cationic porphyrin and GO, rather than RGO sheets, can facilitate the incorporation of iron (III ions into the porphyrin moieties, due to the presence of the oxygen-contained groups at the basal plane of GO sheets served as auxiliary coordination units, which can high-efficiently obstruct the electron transfer from excited porphyrin to GO sheets and result in the occurrence of fluorescence restoration. Thus, a fluorescence sensing platform has been developed for iron (III ions detection in this contribution by using the porphyrin/GO nanohybrids as an optical probe, and our present one exhibited rapid and sensitive responses and high selectivity toward iron (III ions.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Dual-sensing porphyrin-containing copolymer nanosensor as full-spectrum colorimeter and ultra-sensitive thermometer.

    Science.gov (United States)

    Yan, Qiang; Yuan, Jinying; Kang, Yan; Cai, Zhinan; Zhou, Lilin; Yin, Yingwu

    2010-04-28

    A porphyrin-containing copolymer has dual-sensing in response to metal ions and temperature as a novel nanosensor. Triggered by ions, the sensor exhibits full-color tunable behavior as a cationic detector and colorimeter. Responding to temperature, the sensor displays an "isothermal" thermochromic point as an ultra-sensitive thermometer.

  1. 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

  2. Layered silicate films with photochemically active porphyrin cations

    Czech Academy of Sciences Publication Activity Database

    Čeklovský, A.; Czímerová, A.; Lang, Kamil; Bujdák, J.

    2009-01-01

    Roč. 81, č. 8 (2009), s. 1385-1396 ISSN 0033-4545 R&D Projects: GA AV ČR KAN100500651; GA ČR(CZ) GA203/06/1244 Grant - others:GA(SK) VEGA2/6180/27 Institutional research plan: CEZ:AV0Z40320502 Keywords : clay minerals * layer charge * smectites Subject RIV: CA - Inorganic Chemistry Impact factor: 2.289, year: 2009

  3. 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.

  4. N-Confused Porphyrin Immobilized on Solid Supports: Synthesis and Metal Ions Sensing Efficacy

    Directory of Open Access Journals (Sweden)

    Sara R. D. Gamelas

    2018-04-01

    Full Text Available In this work, the N-confused porphyrin 5,10,15,20-tetraphenyl-2-aza-21-carbaporphyrin (NCTPP was immobilized on neutral or cationic supports based on silica and on Merrifield resin. The new materials were characterized by appropriate techniques (UV-Vis spectroscopy, SEM, and zeta potential analysis. Piezoelectric quartz crystal gold electrodes were coated with the different hybrids and their ability to interact with heavy metals was evaluated. The preliminary results obtained showed that the new materials can be explored for metal cations detection and the modification of the material surface is a key factor in tuning the metal selectivity.

  5. 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

  6. 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.

  7. 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.

  8. Structure Optimization of 21,23-Core-Modified Porphyrins Absorbing Long-Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells

    National Research Council Canada - National Science Library

    Detty, Michael R

    2007-01-01

    .... The structures of two derivatives were determined unambiguously be x-ray crystallography including the structure of a cis-ABCC meso-substituted derivative and the structure of a cis-AB disubstituted derivative...

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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...

  14. 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.

  15. 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

  16. Influence of aqueous media properties on aggregation and solubility of four structurally related meso-porphyrin photosensitizers evaluated by spectrophotometric measurements.

    Science.gov (United States)

    Sobczyński, J; Tønnesen, H H; Kristensen, S

    2013-02-01

    Porphyrin photosensitizers tend to aggregate in aqueous solutions even in the micromolar concentration range. This is a challenge during formulation of e.g., parenteral preparations for photodynamic cancer therapy, or preparations for local or topical administration in antimicrobial photodynamic therapy. Monomerization is essential to achieve biocompatible drug formulations of high bioavailability and physiological response (i.e., photoreactivity) and low toxicity. The aggregation and solubilization of four structurally related meso-tetraphenyl porphyrin photosensitizers with nonionic (4-hydroxy), anionic (4-sulphonate; 4-carboxy) and cationic (4-trimethylanilinium) substituents were evaluated in various vehicles by use of UV-Vis spectroscopy. Substituents, overall charge and charge distribution influenced the pKa-values and interaction of the porphyrins with different solvents, excipients and impurities. Modification of medium polarity and solubilization by the nonionic surfactant Tween 80 adjusted the acid-base equilibria and increased the solubility by reduction of porphyrin aggregation. The selected porphyrins were sensitive towards ionic strength, temperature and inorganic impurities to various extents. The results will be further used during development of parenteral and topical formulations of porphyrin photosensitizers for use in photodynamic therapy of cancer and bacterial infections.

  17. A Highly Stable Porphyrinic Zirconium Metal–Organic Framework with shp-a Topology

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Dawei; Gu, Zhi-Yuan; Chen, Ying-Pin; Park, Jihye; Wei, Zhangwen; Sun, Yujia; Bosch, Mathieu; Yuan, Shuai; Zhou, Hong-Cai

    2014-12-24

    Through a kinetically controlled synthetic process, we synthesized PCN-223, a new porphyrinic Zr-MOF constructed from the newly reported hexagonal prismatic 12-connected Zr6 cluster through an unusual disordered arrangement, giving rise to the first example of the shp-a network in MOFs. With its extremely high connectivity, PCN-223 shows high stability in aqueous solutions with a wide range of pH. Cationic PCN-223(Fe) formed by postsynthetic treatment is an excellent recyclable heterogeneous catalyst for the hetero-Diels–Alder reaction.

  18. Quantum confinement-tunable intersystem crossing and the triplet state lifetime of cationic porphyrin–CdTe quantum dot nano-assemblies

    KAUST Repository

    Ahmed, Ghada H.

    2015-03-27

    Here, we report a ground-state interaction between the positively charged cationic porphyrin and the negatively charged carboxylate groups of the thiol ligands on the surface of CdTe quantum dots (QDs), leading to the formation of a stable nanoassembly between the two components. Our time-resolved data clearly demonstrate that we can dramatically tune the intersystem crossing (ISC) and the triplet state lifetime of porphyrin by changing the size of the QDs in the nanoassembly.

  19. Quantum confinement-tunable intersystem crossing and the triplet state lifetime of cationic porphyrin–CdTe quantum dot nano-assemblies

    KAUST Repository

    Ahmed, Ghada H.; Aly, Shawkat Mohammede; Usman, Anwar; Eita, Mohamed Samir; Melnikov, Vasily; Mohammed, Omar F.

    2015-01-01

    Here, we report a ground-state interaction between the positively charged cationic porphyrin and the negatively charged carboxylate groups of the thiol ligands on the surface of CdTe quantum dots (QDs), leading to the formation of a stable nanoassembly between the two components. Our time-resolved data clearly demonstrate that we can dramatically tune the intersystem crossing (ISC) and the triplet state lifetime of porphyrin by changing the size of the QDs in the nanoassembly.

  20. 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.

  1. Electron transfer between a zinc porphyrin photo-sensitized in the visible, and various acceptors, in aqueous and micellar solutions

    International Nuclear Information System (INIS)

    Le Roux, Dominique

    1983-01-01

    This research thesis addresses the study of reactions occurring during the transformation of solar energy in chemical energy, and more precisely the search for photochemical systems allowing the dissociation of water into hydrogen and oxygen. In this study on water photolysis, the author chose to use a porphyrin soluble in water, the zinc tetra-meta-N-methylpyridinium porphyrin, as one of its isomer provided a good efficiency in hydrogen formation. Before reporting the study of electron photo-transfer, the author reports the study of photo-physical and photochemical properties of this porphyrin. Then, in the case of a well known electron acceptor (methyl viologen), he studied the influence of Coulomb effects on the kinetics of direct electron transfer, and on the kinetics of recombination of formed species. He also studied the influence of organised systems (cationic micelles) on these reactions when using a viologen with long chains. He finally reports the study of reactions of the triplet state of this porphyrin with metallic complexes

  2. Endogenous and exogenous porphyrins as photosensitizers in the Hep-2 human carcinoma cell line.

    Science.gov (United States)

    Alvarez, M G; Milanesio, M; Rivarola, V; Durantini, E; Batlle, A; Fukuda, H

    2009-07-01

    The photodynamic activity of three photosensitizers (PS): AL-induced PPIX, the porphyrin derivative 5-(4-trimethylammoniumphenyl)-10, 5, 20-tris (2,4,6- trimethoxyphenyl) porphyrin (CP) and the molecular dyad porphyrin-C(60) (P-C(60)), the last two incorporated into liposomal vesicles, was evaluated on Hep-2 human larynx carcinoma cell line. ALA-induced accumulation of the endogenous PS PPIX, reached saturation values between 5 and 24 h incubation time; the maximal PPIX content was 5.7 nmol/106 cells. The same intracellular level was accumulated when the cationic porphyrin CP was used, while the amount of P-C(60) attained was 1.5 nmol/106 cells. Under violet-blue exciting light, the fluorescence of PPIX and P-C(60) was found in the cytoplasm showing a granular appearance indicating lysosomal localization. CP was mainly detected as a filamentous pattern characteristic of mitochondrial localization. No dark cytotoxicity was observed using 1mM ALA, 5 microM CP and 1 microM P-C(60) after 24 h incubation. Cell morphology was analyzed using Hoechst-33258, toluidine blue staining, TUNEL assay and DNA fragmentation, 24 h after irradiation with 54 J/cm2. When photosensitized with ALA and P-C(60), chromatine condensation characteristic of apoptotic cell death was found; instead, 58 % of necrotic cells were observed with CP. The results show that in the Hep-2 cells, of the three PS analyzed, the molecular dyad P-C(60) was more efficient than CP and PPIX, and confirm that PDT can induce different mechanisms of cell death depending on the PS and the irradiation dose.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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,.

  9. Metal ion attachment to the matrix meso-tetrakis(pentafluorophenyl)porphyrin, related matrices and analytes: an experimental and theoretical study.

    Science.gov (United States)

    van Kampen, Jeroen J A; Luider, Theo M; Ruttink, Paul J A; Burgers, Peter C

    2009-11-01

    In a previous study [van Kampen et al. Analytical Chemistry 2006; 78: 5403], we found that meso-tetrakis (pentafluorophenyl)porphyrin (F20TPP), in combination with lithium salts, provides an efficient matrix to cationize small molecules by Li+ attachment and that this combination can be successfully applied to the quantitative analysis of drugs, such as antiretroviral compounds using matrix-assisted laser desorption ionization in conjunction with a time-of-flight analyzer (MALDI-TOF). In the present study, we further explore the mechanism of metal ion attachment to F20TPP and analytes by MALDI-FTMS(/MS). To this end, we have studied the interaction of F20TPP and analytes with various mono-, di- and trivalent metal ions (Li+, Na+, K+, Rb+, Cs+, Co2+, Cu2+, Zn2+, Fe2+, Fe3+ and Ga3+). For the alkali cations, we find that F20TPP forms complexes only with Li+ and Na+; in addition, model analyte molecules such as poly(ethyleneglycol)s, mixed with F20TPP and the alkali cations, also only form Li+ and Na+ adducts. This contrasts sharply with the commonly used matrix 2,5-dihydroxybenzoic acid, where analytes are most efficiently cationized by Na+ or K+. Reasons for this difference are delineated. Ab initio calculations on porphyrin itself reveal that even the smallest alkali cation, Li+, does not fit in the porphyrin cavity, but lies on top of it, pushing the 21H and 23 H hydrogen atoms out of and below the plane with concomitant bending of the porphyrin skeleton in the opposite direction, i.e. toward the cation. Thus, the Li+ ion is not effectively sequestered and is in fact exposed and thus accessible for donation to analyte molecules. Interaction of F20TPP with di- and trivalent metal ions leads to protoporphyrin-metal ions, where the metal ion is captured within the protoporphyrin dianion cavity. The most intense signal is obtained when F20TPP is reacted with CuCl2 and then subjected to laser ablation. This method presents an easy general route to study the metal

  10. Photophysical Properties and Photoinduced Electron Transfer Within Host-Guest Complexes of 5,10,15,20-Tetrakis(4-N-methylpyridyl)porphyrin with Water-soluble Calixarenes and Cyclodextrins

    Czech Academy of Sciences Publication Activity Database

    Lang, Kamil; Kubát, Pavel; Lhoták, P.; Mosinger, J.; Wagnerová, Dana Marie

    2001-01-01

    Roč. 74, č. 4 (2001), s. 558-565 ISSN 0031-8655 R&D Projects: GA ČR GA203/99/1163 Institutional research plan: CEZ:AV0Z4032918 Keywords : ammonium cations * porphyrin dimers * binding Subject RIV: CA - Inorganic Chemistry Impact factor: 2.146, year: 2001

  11. [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.

  12. 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...

  13. 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)

  14. 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)

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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 ...

  2. 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

  3. 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.

  4. 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.

  5. Post-synthetic modification of porphyrin-encapsulating metal-organic materials by cooperative addition of inorganic salts to enhance CO 2/CH 4 selectivity

    KAUST Repository

    Zhang, ZhenJie

    2012-08-21

    Keeping MOM: Reaction of biphenyl-3,4\\',5-tricarboxylate and Cd(NO 3) 2 in the presence of meso-tetra(N-methyl-4-pyridyl) porphine tetratosylate afforded porph@MOM-11, a microporous metal-organic material (MOM) that encapsulates cationic porphyrins and solvent in alternating open channels. Porph@MOM-11 has cation and anion binding sites that facilitate cooperative addition of inorganic salts (such as M +Cl -) in a stoichiometric fashion. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Post-synthetic modification of porphyrin-encapsulating metal-organic materials by cooperative addition of inorganic salts to enhance CO 2/CH 4 selectivity

    KAUST Repository

    Zhang, ZhenJie; Gao, Wenyang; Wojtas, Łukasz; Ma, Shengqian; Eddaoudi, Mohamed; Zaworotko, Michael J.

    2012-01-01

    Keeping MOM: Reaction of biphenyl-3,4',5-tricarboxylate and Cd(NO 3) 2 in the presence of meso-tetra(N-methyl-4-pyridyl) porphine tetratosylate afforded porph@MOM-11, a microporous metal-organic material (MOM) that encapsulates cationic porphyrins and solvent in alternating open channels. Porph@MOM-11 has cation and anion binding sites that facilitate cooperative addition of inorganic salts (such as M +Cl -) in a stoichiometric fashion. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 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

  8. Visible light-driven O2 reduction by a porphyrin-laccase system.

    Science.gov (United States)

    Lazarides, Theodore; Sazanovich, Igor V; Simaan, A Jalila; Kafentzi, Maria Chrisanthi; Delor, Milan; Mekmouche, Yasmina; Faure, Bruno; Réglier, Marius; Weinstein, Julia A; Coutsolelos, Athanassios G; Tron, Thierry

    2013-02-27

    Several recent studies have shown that the combination of photosensitizers with metalloenzymes can support a light-driven multielectron reduction of molecules such as CO(2) or HCN. Here we show that the association of the zinc tetramethylpyridinium porphyrin (ZnTMPyP(4+)) photosensitizer with the multicopper oxidase (MCO) laccase allows to link the oxidation of an organic molecule to the four electrons reduction of dioxygen into water. The enzyme is photoreduced within minutes with porphyrin/enzyme ratio as low as 1:40. With a 1:1 ratio, the dioxygen consumption rate is 1.7 μmol L(-1) s(-1). Flash photolysis experiments support the formation of the triplet excited state of ZnTMPyP(4+) which reduces the enzyme to form a radical cation of the porphyrin with a k(ET) ≈ 10(7) s(-1) M(-1). The long-lived triplet excited state of the ZnTMPyP(4+) (τ(0) = 0.72 ms) accounts for a substantial electron-transfer quantum yield, φ(ET) = 0.35. Consequently, the enzyme-dependent photo-oxidation of the electron donor occurs with a turnover of 8 min(-1) for the one-electron oxidation process, thereby supporting the suitability of such enzyme/sensitizer hybrid systems for aerobic photodriven transformations on substrates. This study is the first example of a phorphyrin-sensitized four-electron reduction of an enzyme of the MCO family, leading to photoreduction of dioxygen into water.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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)

  18. 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

  19. 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

  20. 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.

  1. 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 ...

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomeri- zation of the linear propargyl cation to ..... C3, C4 and C5. The ZPE corrections in each case are derived from the. B3LYP calculations. ..... the converse of which gives the relative capacity of the. LPD's to stabilize TS6 with respect ...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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...

  17. Cation Exchange Water Softeners

    Science.gov (United States)

    WaterSense released a notice of intent to develop a specification for cation exchange water softeners. The program has made the decision not to move forward with a spec at this time, but is making this information available.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. Optical transition rates of a meso-substituted thiacarbocyanine in methanol-in-oil reverse micelles

    International Nuclear Information System (INIS)

    Oezcelik, Serdar; Zeynep Atay, N.

    2005-01-01

    We report the photophysical properties of 3,3'-diethyl-5,5'-dichloro-9-phenylthiacarbocyanine (DDPT) in methanol-in-oil (m/o) reverse micellar systems which form methanol droplets stabilized with anionic surfactant aerosol-OT (AOT) in n-heptane. The fluorescence quantum yield of DDPT is enhanced by a factor of 17 in the methanol droplet in comparison with bulk methanol. The fluorescence lifetimes of DDPT in m/o reverse micelles are prolonged up to 2.2 ns with increasing molar ratio of methanol to surfactant (w 0 =[MeOH]/[AOT]), whereas the fluorescence lifetime of DDPT in bulk methanol is 75 ps. The non-radiative rate constants of DDPT in the droplets are decreased by a factor of 40, resulting in a remarkable enhancement in quantum yields, indicating that internal motions of DDPT in the droplets are significantly reduced due to strong electrostatic interactions between the positively charged DDPT and the negatively charged sulfonate head-groups of AOT and the spatial confinement induced by the reverse micellar structure

  6. A New Approach to Non-Coordinating Anions: Lewis Acid Enhancement of Porphyrin Metal Centers in a Zwitterionic Metal$-$Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jacob A. [Univ. of Nebraska, Lincoln, NE (United States). Dept. of Chemistry; Petersen, Brenna M. [Univ. of Nebraska, Lincoln, NE (United States). Dept. of Chemistry; Kormos, Attila [Hungarian Academy of Sciences, Budapest (Hungary); Echeverría, Elena [Univ. of Nebraska, Lincoln, NE (United States). Dept. of Physics and Astronomy; Chen, Yu-Sheng [Univ. of Chicago, Argonne, IL (United States). ChemMatCARS, Center for Advanced Radiation Sources; Zhang, Jian [Univ. of Nebraska, Lincoln, NE (United States). Dept. of Chemistry

    2017-02-28

    Here, we describe a new strategy to generate non-coordinating anions using zwitterionic metal–organic frameworks (MOFs). By assembly of anionic inorganic secondary building blocks (SBUs) ([In(CO2)4]$-$) with cationic metalloporphyrin-based organic linkers, we prepared zwitterionic MOFs in which the complete internal charge separation effectively prevents the potential binding of the counteranion to the cationic metal center. We demonstrate the enhanced Lewis acidity of MnIII- and FeIII-porphyrins in the zwitterionic MOFs in three representative electrocyclization reactions: [2 + 1] cycloisomerization of enynes, [3 + 2] cycloaddition of aziridines and alkenes, and [4 + 2] hetero-Diels–Alder cycloaddition of aldehydes with dienes. Lastly, this work paves a new way to design functional MOFs for tunable chemical catalysis.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. Manganese(III Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations

    Directory of Open Access Journals (Sweden)

    Eugenia Fagadar-Cosma

    2010-09-01

    Full Text Available Two manganese(III porphyrins: manganese(III tetraphenylporphyrin chloride and manganese(III-tetrakis(3-hydroxyphenylporphyrin chloride were tested as ionophores for the construction of new diclofenac−selective electrodes. The electroactive material was incorporated either in PVC or a sol−gel matrix. The effect of different plasticizers and additives (anionic and cationic on the potentiometric response was studied. The best results were obtained for the PVC membrane plasticized with dioctylphtalate and having sodium tetraphenylborate as a lipophilic anionic additive incorporated. The sensor response was linear in the concentration range 3 × 10−6 – 1 × 10−2 M with a slope of −59.7 mV/dec diclofenac, a detection limit of 1.5 × 10−6 M and very good selectivity coefficients. It was used for the determination of diclofenac in pharmaceutical preparations, by direct potentiometry. The results were compared with those obtained by the HPLC reference method and a good agreement was found between the two methods.

  12. Cation radicals of xanthophylls.

    Science.gov (United States)

    Galinato, Mary Grace I; Niedzwiedzki, Dariusz; Deal, Cailin; Birge, Robert R; Frank, Harry A

    2007-10-01

    Carotenes and xanthophylls are well known to act as electron donors in redox processes. This ability is thought to be associated with the inhibition of oxidative reactions in reaction centers and light-harvesting pigment-protein complexes of photosystem II (PSII). In this work, cation radicals of neoxanthin, violaxanthin, lutein, zeaxanthin, beta-cryptoxanthin, beta-carotene, and lycopene were generated in solution using ferric chloride as an oxidant and then studied by absorption spectroscopy. The investigation provides a view toward understanding the molecular features that determine the spectral properties of cation radicals of carotenoids. The absorption spectral data reveal a shift to longer wavelength with increasing pi-chain length. However, zeaxanthin and beta-cryptoxanthin exhibit cation radical spectra blue-shifted compared to that of beta-carotene, despite all of these molecules having 11 conjugated carbon-carbon double bonds. CIS molecular orbital theory quantum computations interpret this effect as due to the hydroxyl groups in the terminal rings selectively stabilizing the highest occupied molecular orbitals of preferentially populated s-trans-isomers. The data are expected to be useful in the analysis of spectral results from PSII pigment-protein complexes seeking to understand the role of carotene and xanthophyll cation radicals in regulating excited state energy flow, in protecting PSII reaction centers against photoinhibition, and in dissipating excess light energy absorbed by photosynthetic organisms but not used for photosynthesis.

  13. Identifi cation of Sectarianism

    Directory of Open Access Journals (Sweden)

    Martinovich Vladimir

    2016-03-01

    Full Text Available «New religious movements and society» is traditionally one of the most sophisticated topics in the area of new religions studies. Its problem field is so huge that up to now by far not all important research themes where even touched by scientists from all over the world. The problem of the process of the identification of sectarianism by diff erent societal institutions is one of such untouched themes that is taken as the main subject of this article. This process by itself is an inseparable part of the every societal deliberate reaction to the very existence of unconventional religiosity, its unstructured and mainly structured types. The focal point of the article is step-by-step analysis of the general structure elements of the process of the identification of sectarianism without any reference to the specific time and place of its flow. Special attention is paid to the analysis of the subjects of the identification of sectarianism, to the criteria for religious groups to be qualified as new religious movements, and to the specific features of the process of documents filtration. The causes of selective perception of sectarianism are disclosed. Some main consequences and unpredictable outcomes of the process of the identification of sectarianism are described.

  14. 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...

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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...

  5. 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.

  6. 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

  7. 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.

  8. Effect of porphyrin on photocatalytic activity of TiO2 nanoparticles toward Rhodamine B photodegradation.

    Science.gov (United States)

    Ahmed, M A; Abou-Gamra, Z M; Medien, H A A; Hamza, M A

    2017-11-01

    As known, porphyrins have central role in photosynthesis, biological oxidation and reduction and oxygen transport beside to their intensive color which qualify them to be good photosensitizers. Herein, tetra (4-carboxyphenyl) porphyrin (TCPP) was prepared by a simple one-pot synthesis to use as a visible antenna for TiO 2 nanoparticles that were prepared via a simple template-free sol-gel method. Various loading percentages of TCPP (0.05-1%) were incorporated on the surface of TiO 2 as photosensitizer for photocatalytic degradation of Rhodamine B (Rh B) dye as a primary cationic pollutant model. Among them, 0.1% TCPP-TiO 2 was the most reactive sample. It was found that the photoactivity of 0.1% TCPP-TiO 2 sample (0.5g/L) was approximately 1.5 times greater than that of pure TiO 2 (0.5g/L) toward the degradation of Rh B (1×10 -5 M) under UV-A irradiation. Transient fluorescence decay measurements showed that the life time of TiO 2 excited state has doubled after anchoring TCPP, thus the probability of electron-hole recombination has decreased. The samples were characterized by XRD, HR-TEM, DRS and N 2 adsorption-desorption isotherms. The XRD patterns confirmed the successful preparation of TiO 2 nanoparticles with average crystalline size of 25.7nm. Also, XRD patterns suggested the presence of mixed phase TiO 2 nanoparticles of 77% anatase and 23% rutile. DRS showed that the characteristic peaks of TCPP covered the whole visible range 400-700nm. HR-TEM images showed the spheroids shape of TiO 2 nanoparticles and confirmed the presence of anatase and rutile phases as suggested from XRD data. The different parameters affecting the photodegradation of Rh B dye such as catalyst dose, dye concentration and pH were studied to obtain the optimum conditions. Almost complete degradation of Rh B was obtained which confirmed by HPLC and TOC measurements. The effect of scavengers was studied to indicate the most active species. TCPP-TiO 2 gave a good response toward the

  9. 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.

  10. Antibacterial effect of cationic porphyrazines and anionic phthalocyanine and their interaction with plasmid DNA

    Science.gov (United States)

    Hassani, Leila; Hakimian, Fatemeh; Safaei, Elham; Fazeli, Zahra

    2013-11-01

    Resistance to antibiotics is a public health issue and identification of new antibacterial agents is one of the most important goals of pharmacological research. Among the novel developed antibacterial agents, porphyrin complexes and their derivatives are ideal candidates for use in medical applications. Phthalocyanines differ from porphyrins by having nitrogen atoms link the individual pyrrol units. The aza analogues of the phthalocyanines (azaPcs) such as tetramethylmetalloporphyrazines are heterocyclic Pc analogues. In this investigation, interaction of an anionic phthalocyanine (Cu(PcTs)) and two cationic tetrapyridinoporphyrazines including [Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+ complexes with plasmid DNA was studied using spectroscopic and gel electrophoresis methods. In addition, antibacterial effect of the complexes against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was investigated using dilution test method. The results indicated that both porphyrazines have significant antibacterial properties, but Cu(PcTs) has weak antibacterial effect. Compairing the binding of the phthalocyanine and the porphyrazines to DNA demonstrated that the interaction of cationic porphyrazines is stronger than the anionic phthalocyanine remarkably. The extent of hypochromicity and red shift of absorption spectra indicated preferential intercalation of the two porphyrazine into the base pairs of DNA helix. Gel electrophoresis result implied Cu(2,3-tmtppa) and Cu(3,4-tmtppa) are able to perform cleavage of the plasmid DNA. Consequently, DNA binding and cleavage might be one of the antibacterial mechanisms of the complexes.

  11. 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)

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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+.

  3. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  4. 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)

  5. 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)

  6. 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

  7. 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)

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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...

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu

    2017-04-27

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  7. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu; Tian, Qiwei; Dong, Xinglong; Liu, Zhaohui; Basset, Jean-Marie; Saih, Youssef; Sun, Miao; Xu, Wei; Shaikh, Sohel

    2017-01-01

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  8. 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.

  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. The cation-π interaction.

    Science.gov (United States)

    Dougherty, Dennis A

    2013-04-16

    The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author's perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forego aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction (Li(+) binds to benzene with 38 kcal/mol of binding energy; NH4(+) with 19 kcal/mol) distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2-5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) C(δ-)-H(δ+) bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li(+) > Na(+) > K(+) > Rb(+): as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane is

  11. Synthetic cation-selective nanotube: permeant cations chaperoned by anions.

    Science.gov (United States)

    Hilder, Tamsyn A; Gordon, Dan; Chung, Shin-Ho

    2011-01-28

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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)

  20. 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.

  1. 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

  2. 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

  3. The porphyrin-fullerene nanoparticles to promote the ATP overproduction in myocardium: 25Mg2+-magnetic isotope effect.

    Science.gov (United States)

    Rezayat, S M; Boushehri, S V S; Salmanian, B; Omidvari, A H; Tarighat, S; Esmaeili, S; Sarkar, S; Amirshahi, N; Alyautdin, R N; Orlova, M A; Trushkov, I V; Buchachenko, A L; Liu, K C; Kuznetsov, D A

    2009-04-01

    This is a first case ever reported on the fullerene-based low toxic nanocationite particles (porphyrin adducts of cyclohexyl fullerene-C(60)) designed for targeted delivery of the paramagnetic magnesium stable isotope to the heart muscle providing a sharp clinical effect close to about 80% recovery of the tissue hypoxia symptoms in less than 24 h after a single injection (0.03-0.1 LD(50)). A whole principle of this therapy is novel: (25)Mg(2+)-magnetic isotope effect selectively stimulates the ATP overproduction in the oxygen-depleted cells due to (25)Mg(2+) released by the nanoparticles. Being membranotropic cationites, these "smart nanoparticles" release the overactivating paramagnetic cations only in response to the metabolic acidic shift. The resulting positive changes in the heart cell energy metabolism may help to prevent and/or treat the local myocardial hypoxic disorders and, hence, protect the heart muscle from a serious damage in a vast variety of the hypoxia-caused clinical situations including both doxorubicin and 1-methylnicotineamide cardiotoxic side effects. Both pharmacokinetics and pharmacodynamics of the drug proposed make it suitable for safe and efficient administration in either single or multi-injection (acute or chronic) therapeutic schemes.

  4. Simultaneous anionic and cationic redox

    Science.gov (United States)

    Jung, Sung-Kyun; Kang, Kisuk

    2017-12-01

    It is challenging to unlock anionic redox activity, accompanied by full utilization of available cationic redox process, to boost capacity of battery cathodes. Now, material design by tuning the metal-oxygen interaction is shown to be a promising solution.

  5. 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

  6. Cation disorder in Ga1212.

    Science.gov (United States)

    Greenwood, K B; Ko, D; Vander Griend, D A; Sarjeant, G M; Milgram, J W; Garrity, E S; DeLoach, D I; Poeppelmeier, K R; Salvador, P A; Mason, T O

    2000-07-24

    Substitution of calcium for strontium in LnSr2-xCaxCu2GaO7 (Ln = La, Pr, Nd, Gd, Ho, Er, Tm, and Yb) materials at ambient pressure and 975 degrees C results in complete substitution of calcium for strontium in the lanthanum and praseodymium systems and partial substitution in the other lanthanide systems. The calcium saturation level depends on the size of the Ln cation, and in all cases, a decrease in the lattice parameters with calcium concentration was observed until a common, lower bound, average A-cation size is reached. Site occupancies from X-ray and neutron diffraction experiments for LnSr2-xCaxCu2GaO7 (x = 0 and x = 2) confirm that the A-cations distribute between the two blocking-layer sites and the active-layer site based on size. A quantitative link between cation distribution and relative site-specific cation enthalpy for calcium, strontium, and lanthanum within the gallate structure is derived. The cation distribution in other similar materials can potentially be modeled.

  7. 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.

  8. Molecular-structure control of ultrafast electron injection at cationic porphyrin-CdTe quantum dot interfaces

    KAUST Repository

    Aly, Shawkat Mohammede; Ahmed, Ghada H.; Shaheen, Basamat; Sun, Jingya; Mohammed, Omar F.

    2015-01-01

    Charge transfer (CT) at donor (D)/acceptor (A) interfaces is central to the functioning of photovoltaic and light-emitting devices. Understanding and controlling this process on the molecular level has been proven to be crucial for optimizing

  9. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    Muller, W.

    2010-01-01

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl - , NO 3 - , C 2 O 4 2- ) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu 2+ , Zn 2+ , UO 2 2+ , Fe 3+ , Nd 3+ , Eu 3+ , Th 4+ ) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author) [fr

  10. 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.

  11. 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.

  12. 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.

  13. Potentiation of radiation-induced cell kill by synthetic metalloporphyrins

    International Nuclear Information System (INIS)

    O'Hara, J.A.; Douple, E.B.; Abrams, M.J.; Picker, D.J.; Giandomenico, C.M.; Vollano, J.F.

    1989-01-01

    The effects of the combination of several meso-substituted, water soluble metalloporphyrins with ionizing radiation on hypoxic and oxic monolayers of Chinese hamster fibroblast (V79N) cells were studied. The metalloporphyrins tested included a series of cationic metalloporphyrins complexed with Co(III), Zn(II), Fe(III), Cu(II), Pd(II) or Mn(III) and a series of anionic porphyrins chelated with Co(III), Fe(III), Cu(II), Rh(III), Mn(III) or Sn(IV). Both cationic and anionic free porphyrins were also tested. Cationic ligands were tetrakis(4N-methylpyridyl)porphine [TMPyP], tetrakis(4N-trimethylamino phenyl)porphine [TMAP], tetrakis(4N-butylpyridyl)porphine [TBPyP] and tetrakis(3N-methylpyridyl)porphine [3TMPyP]. Anionic ligands tested were tetrakis(4-sulfonato phenyl)porphine [TPPS], tetrakis(biphenyl)porphine sulfonate [TBPS] and tetrakis(4-carboxyphenyl)porphine [TCPP]. SER calculated from survival curves and SFR from one radiation dose were used to assess the relative effectiveness of this class as non-cytotoxic hypoxic and oxic cell-kill potentiators. Comparisons were made at 100 microM, which was essentially non-toxic (greater than 70% survival) for all porphyrins tested except for Co[TMPyP] (approximately 50% survival after 1 hour at 37 degrees C under oxic conditions). The greatest effects on radiation-induced cell kill were achieved with Co[TPPS] and Co[TMPyP] with SER values of 2.3 and 2.4 respectively. Porphyrin analogs with no coordinated metal were found to be less active than the same compound with metal. The overall charge on the molecule did not systematically relate to the biological activity of the compounds tested

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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....

  14. 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.

  15. 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.

  16. 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.

  17. New double-cation borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Lindemann, Inge; Domenech Ferrer, Roger; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, Institute for Metallic Materials, P.O. Box 270016, 01171 Dresden (Germany); Filinchuk, Yaroslav [Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Hagemann, Hans; Cerny, Radovan [Department of Physical Chemistry and Crystallography, University of Geneva, 1211 Geneva (Switzerland)

    2011-07-01

    Complex hydrides are under consideration for on-board hydrogen storage due to their high hydrogen density. However, up to now conventional borohydrides are either too stable or unstable for applications as in PEM fuel cells (60-120 C). Recently, double-cation borohydride systems have attracted great interest. The desorption temperature of the borohydrides decreases with increasing electronegativity of the cation. Consequently, it is possible to tailor a feasible on-board hydrogen storage material by the combination of appropriate cations. The stability was found to be intermediate between the single-cation borohydride systems. Two combinations were sucessfully synthesised by metathesis reaction via high energy ball milling. Al-Li-borohydride shows desorption at about 70 C combined with a very high hydrogen density (17.2 wt.%) and the Na-Al-borohydride (14.2 wt.%) decomposes around 90 C. Both desorption temperatures are in the target range for applications. The decomposition pathways were observed by in-situ-Raman spectroscopy, DSC (Differential Scanning Calorimetry), TG (Thermogravimetry) and thermal desorption measurements.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Liquid-solid extraction of metallic cations by cationic amphiphiles

    International Nuclear Information System (INIS)

    Mueller, Wolfram; Sievers, Torsten K.; Zemb, Thomas; Diat, Olivier; Sievers, Torsten K.; Dejugnat, Christophe

    2012-01-01

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  3. Comparative study of the interaction of meso-tetrakis (N-para-trimethyl-anilium) porphyrin (TMAP) in its free base and Fe derivative form with oligo(dA.dT)15 and oligo(dG.dC)15.

    Science.gov (United States)

    Bathaie, S Zahra; Ajloo, Davood; Daraie, Marzieh; Ghadamgahi, Maryam

    2015-01-01

    Interaction between a cationic porphyrin and its ferric derivative with oligo(dA.dT)15 and oligo(dG.dC)15 was studied by UV-vis spectroscopy, resonance light scattering (RLS), and circular dichroism (CD) at different ionic strengths; molecular docking and molecular dynamics simulation were also used for completion. Followings are the observed changes in the spectral properties of meso-tetrakis (N-para-trimethyl-anilium) porphyrin (TMAP), as a free-base porphyrin with no axial ligand, and its Fe derivative (FeTMAP) upon interaction with oligo(dA.dT)15 and oligo(dG.dC)15: (1) the substantial red shift and hypochromicity at the Soret maximum in the UV-vis spectra; (2) the increased RLS intensity by increasing the ionic strength; and (3) an intense bisignate excitonic CD signal. All of them are the reasons for TMAP and FeTMAP binding to oligo(dA.dT)15 and oligo(dG.dC)15 with the outside binding mode, accompanied by the self-stacking of the ligands along the oligonucleotide helix. The CD results demonstrated a drastic change from excitonic in monomeric behavior at higher ionic strengths, which indicates the groove binding of the ligands with oligonucleotides. Molecular docking also confirmed the groove binding mode of the ligands and estimated the binding constants and energies of the interactions. Their interaction trend was further confirmed by molecular dynamics technique and structure parameters obtained from simulation. It showed that TMAP reduced the number of intermolecular hydrogen bonds and increased the solvent accessible surface area in the oligonucleotide. The self-aggregation of ligands at lower concentrations was also confirmed.

  4. 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.

  5. 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)

  6. Tripodal receptors for cation and anion sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Verboom, Willem; Reinhoudt, David

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  7. Heavy metal cations permeate the TRPV6 epithelial cation channel.

    Science.gov (United States)

    Kovacs, Gergely; Danko, Tamas; Bergeron, Marc J; Balazs, Bernadett; Suzuki, Yoshiro; Zsembery, Akos; Hediger, Matthias A

    2011-01-01

    TRPV6 belongs to the vanilloid family of the transient receptor potential channel (TRP) superfamily. This calcium-selective channel is highly expressed in the duodenum and the placenta, being responsible for calcium absorption in the body and fetus. Previous observations have suggested that TRPV6 is not only permeable to calcium but also to other divalent cations in epithelial tissues. In this study, we tested whether TRPV6 is indeed also permeable to cations such as zinc and cadmium. We found that the basal intracellular calcium concentration was higher in HEK293 cells transfected with hTRPV6 than in non-transfected cells, and that this difference almost disappeared in nominally calcium-free solution. Live cell imaging experiments with Fura-2 and NewPort Green DCF showed that overexpression of human TRPV6 increased the permeability for Ca(2+), Ba(2+), Sr(2+), Mn(2+), Zn(2+), Cd(2+), and interestingly also for La(3+) and Gd(3+). These results were confirmed using the patch clamp technique. (45)Ca uptake experiments showed that cadmium, lanthanum and gadolinium were also highly efficient inhibitors of TRPV6-mediated calcium influx at higher micromolar concentrations. Our results suggest that TRPV6 is not only involved in calcium transport but also in the transport of other divalent cations, including heavy metal ions, which may have toxicological implications. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. 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.

  9. 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

  10. 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.

  11. Cationic electrodepositable coating composition comprising lignin

    Science.gov (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  12. 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.

  13. 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.

  14. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... highly enantioselective silylation reactions in polyether-generated chiral environments, and leading to a record-high turnover in asymmetric organocatalysis. This can lead to further applications by the asymmetric use of other inorganic salts in various organic transformations....

  15. 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.

  16. 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.

  17. 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...

  18. 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

  19. 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.

  20. 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...

  1. 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...

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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)

  11. 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

  12. 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.

  13. 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

  14. 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....

  15. 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.

  16. 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

  17. 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.

  18. 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.

  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

  1. Synthesis and biological evaluation of porphyrin-polyamine conjugates as potential agents in photodynamic therapy

    International Nuclear Information System (INIS)

    Lamarche, Francois

    2004-01-01

    The synthesis of photosensitizers that specifically recognize tumoral cells constitutes a challenging step in the field of photodynamic therapy. To this end, we designed a new class of porphyrins linked to natural polyamines (spermidine, spermine). As a first step, we synthesized para and ortho-carboxy-propyl-oxy-phenyl-tritolyl-porphyrins bearing spermidine or spermine. Then, we designed two precursors, N4-aminobutyl-spermidine-Boc2 and N4-aminobutyl-spermine-Boc3. These derivatives have been fixed on carboxy-porphyrins, protoporphyrin IX and chlorin e6. These new compounds have been characterized by MALDI spectrometry, UV-Visible and 1 H NMR spectroscopy. They have been found to produce singlet oxygen. Biological activity study of these photosensitizers has been realized on K562 cell line, irradiated with fluorescent bulbs. In vitro tests of these porphyrins have shown their photo-cytotoxic activity and protoporphyrins-polyamines have been able to trigger early apoptotic events. Finally, preliminary results obtained with chlorin e6-polyamines, irradiated with red light, seem to show that these structures are good candidates for an application in PDT. (author) [fr

  2. Porphyrins and pheomelanins contribute to the reddish juvenal plumage of black-shouldered kites.

    Science.gov (United States)

    Negro, Juan J; Bortolotti, Gary R; Mateo, Rafael; García, Isabel M

    2009-07-01

    Porphyrins are a widespread group of pigments in nature, but, contrary to melanins and carotenoids, their occurrence as plumage colorants seems to be anecdotal and their function, if any, is unknown. Using thin-layer chromatography and high pressure liquid chromatography, we have found coproporphyrin III, the same porphyrin type previously reported in owls, in the plumage of nestling black-shouldered kites (Elanus caeruleus). The first plumage grown at the nest in this species includes reddish-brown contour feathers in the upperparts, and particularly in the breast area, which fade during the weeks-long post-fledging period to become either gray or white consistent with the definitive adult plumage. In these reddish feathers, we have also found small amounts of pheomelanins and traces of eumelanin. The contribution of each pigment to the final colour perceived by birds or other animals is unknown. In white and grey feathers of the same species no porphyrin was found, and only traces of eumelanin were detected in the grey ones. The fact that the reddish feathers are only found in the juvenal plumage, when individuals are vulnerable in an open nest, leads us to hypothesize a camouflage role for this ephemeral plumage. As porphyrins are involved, although not exclusively, we can for the first time ascribe them a function in the plumage of birds.

  3. 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.

  4. Biosynthesis of porphyrins and immune status of children and teenagers exposed to irradiation in low doses

    International Nuclear Information System (INIS)

    Grubina, L.A.; Shavrova, Ye.N.; Vorontsova, T.V.; Vinnik, L.M.; Kuchinskaya, E.A.; Khmelevskaya, L.A.

    1999-01-01

    Immunological indices and porphyrins levels were studied in children of various ages living on the radionuclide contaminated territories. A reliable reduction of medium levels of proto- and coproporphyrins in erythrocytes of children and teenagers with the thyroid gland pathologies from radio contaminated regions was revealed. The lowest level of porphyrins was observed in children with thyroid neoplasm. The state of immune system of children with thyroid pathology was characterized by decreasing content of T-lymphocytes production and by stimulation of B-lymphocytes generation despite of the type of thyroid gland disease. Maximal changes of both porphyrins metabolism and T- and B-immune system were registered in children from the Stolin District of the Brest Region with increasing amount of incorporated cesium 137. It could be due to the complex of radio ecological factors. In another investigated groups a correlation between the immune parameters and porphyrins level from the one hand and the level of radionuclide contamination or absorbed amount of cesium 137 in organism from the other hand was not obtained

  5. Photoinduced electron transfer and photocurrent in multicomponent organic molecular films containing oriented porphyrin-fullerene dyad

    NARCIS (Netherlands)

    Kaunisto, Kimmo; Vuorinen, Tommi; Vahasalo, Heidi; Chukharev, Vladimir; Tkachenko, Nikolai V.; Efimov, Alexander; Tolkki, Antti; Lehtivuori, Heli; Lemmetyinen, Helge

    2008-01-01

    Layers of poly(3-hexylthiophene), PHT, phenyl vinyl thiophene, PVT3, poly(p-phenylene-2,3′-bis(3,2′-diphenyl)-quinoxaline-7-7′- diyl), PPQ, and covalently linked porphyrin-fullerene donor-acceptor dyad, P-F, were deposited as various multilayer films, which then were used to study photoinduced

  6. Experimental Determination of Activation Energy of Nucleophilic Aromatic Substitution on Porphyrins

    Science.gov (United States)

    Rizvi, Waqar; Khwaja, Emaad; Siddiqui, Saim; Bhupathiraju, N. V. S. Dinesh K.; Drain, Charles Michael

    2018-01-01

    A physical organic chemistry experiment is described for second-year college students. Students performed nucleophilic aromatic substitution (NAS) reactions on 5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (TPPF[subscript 20]) using three different nucleophiles. Substitution occurs preferentially at the 4-position ("para")…

  7. Tapping the biotechnological potential of insect microbial symbionts: new insecticidal porphyrins.

    Science.gov (United States)

    Martinez, Ana Flávia Canovas; de Almeida, Luís Gustavo; Moraes, Luiz Alberto Beraldo; Cônsoli, Fernando Luís

    2017-06-27

    The demand for sustainable agricultural practices and the limited progress toward newer and safer chemicals for use in pest control maintain the impetus for research and identification of new natural molecules. Natural molecules are preferable to synthetic organic molecules because they are biodegradable, have low toxicity, are often selective and can be applied at low concentrations. Microbes are one source of natural insecticides, and microbial insect symbionts have attracted attention as a source of new bioactive molecules because these microbes are exposed to various selection pressures in their association with insects. Analytical techniques must be used to isolate and characterize new compounds, and sensitive analytical tools such as mass spectrometry and high-resolution chromatography are required to identify the least-abundant molecules. We used classical fermentation techniques combined with tandem mass spectrometry to prospect for insecticidal substances produced by the ant symbiont Streptomyces caniferus. Crude extracts from this bacterium showed low biological activity (less than 10% mortality) against the larval stage of the fall armyworm Spodoptera frugiperda. Because of the complexity of the crude extract, we used fractionation-guided bioassays to investigate if the low toxicity was related to the relative abundance of the active molecule, leading to the isolation of porphyrins as active molecules. Porphyrins are a class of photoactive molecules with a broad range of bioactivity, including insecticidal. The active fraction, containing a mixture of porphyrins, induced up to 100% larval mortality (LD 50  = 37.7 μg.cm -2 ). Tandem mass-spectrometry analyses provided structural information for two new porphyrin structures. Data on the availability of porphyrins in 67 other crude extracts of ant ectosymbionts were also obtained with ion-monitoring experiments. Insect-associated bacterial symbionts are a rich source of bioactive compounds. Exploring

  8. Environmental conditions during the Frasnian-Fammenian mass extinction inferred from chlorophyll-derived porphyrin biomarkers.

    Science.gov (United States)

    Uveges, B. T.; Junium, C. K.; Cohen, P. A.; Boyer, D.

    2014-12-01

    The widespread mass extinction that occurred across the Frasnian- Fammenian (F-F) boundary was one of the largest losses of biodiversity in Earth's history. The F-F extinction interval is expressed in western New York State by two organic rich black shale intervals known as the Upper and Lower Kellwasser events. These shale intervals are well preserved, thermally immature, and are well constrained in age by conodont biostratigraphy, and thus provide an exceptional opportunity to study the organic material originating from the F-F boundary. In order to test hypotheses about the cause(s) and consequences of the FF biotic crisis, a broader knowledge of the organic carbon sources is needed, and a characterization of the marine primary producer communities will assist in this endeavor. One such avenue is through the study of chlorophyll-derived biomarkers (porphyrins). The organic extracts of powdered shale samples from the Kellwasser horizons were analyzed using HPLC/LC-MSn and diode array UV-Vis spectroscopy. Preliminary data from the Kellwasser intervals reveal only one porphyrin, with a mass (M+H) of 600. The UV-Vis absorbance spectrum (Soret = 405nm, α = 533nm, β = 570nm) of the metallated compound is consistent with that of a vanadyl porphyrin with a free-base (M+H) of 535. Collision-induced mass spectra displays mass losses of 43 and 57 daltons, which are consistent with an extended alkyl chain at the C-8 position. Extended alkyl chains at C-8 are exclusively associated with porphyrins derived from bacteriochlorophyll c, d or e. The presence of bacterioporphyrins is congruous with the episodic presence of anoxic and sulfidic conditions in the photic zone. What is surprising is that a bacteriochlorophyll- derived porphyrin is the most abundant in these sequences, and their study may help to elucidate the conditions surrounding the F-F mass extinction, and further constrain the fluctuations in marine oxygen content in the Upper Devonian Appalachian Basin.

  9. Gadolinium-porphyrins: new potential magnetic resonance imaging contrast agents for melanoma detection

    Directory of Open Access Journals (Sweden)

    Daryoush Shahbazi-Gahrouei

    2006-11-01

    Full Text Available BACKGROUND: Two new porphyrin-based magnetic resonance imaging (MRI contrast agents, Gd-hematoporphyrin (Gd-H and Gd-tetra-carboranylmethoxyphenyl-porphyrin (Gd-TCP were synthesized and tested in nude mice with human melanoma (MM-138 xenografts as new melanoma contrast agents. METHODS: Subcutaneous xenografts of human melanoma cells (MM-138 were studied in 30 (five groups of six nude mice. The effect of different contrast agents (Gd-TCP, Gd-H, GdCl3 and Gd-DTPA on proton relaxation times was measured in tumors and other organs. T1 values, signal enhancement and the Gd concentration for different contrast agent solutions were also investigated. RESULTS: The porphyrin agents showed higher relaxivity compared to the clincal agent, Gd-DTPA. A significant 16% and 21% modification in T1 relaxation time of the water in human melanoma tumors grafted in the nude mice was revealed 24 hours after injection of Gd-TCP and Gd-H, respectively. The percentage of injected Gd localized to the tumor measured by inductively coupled plasma atomic emission spectrometry (ICP-AES was approximately 21% for Gd-TCP and 28% for Gd-H which were higher than that of Gd-DTPA (10%. CONCLUSIONS: The high concentration of Gd in the tumor is indicative of a selective retention of the compounds and indicates that Gd-TCP and Gd-H are promising MR imaging contrast agents for melanoma detection. Gd-porphyrins have considerable promise for further diagnostic applications in magnetic resonance imaging. KEY WORDS: MRI, porphyrin-based contrast agent, hematoporphyrin, melanoma.

  10. 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

  11. LDL Receptors as Gateways for Intracellular Porphyrin Uptake

    International Nuclear Information System (INIS)

    Novick, S.; Laster, B.; Quastel, M.

    2004-01-01

    Boronated compounds are currently being studied for possible use in Boron Neutron Capture Therapy (BNCT). We found that one of these agents, BOPP (tetrakis-carborane-carboxylate, esters of 2,4-bis (a,b- dihydroxyethyl) deuteroporphyrin IX), could also be labeled with indium (In-BOPP) and, therefore, could also be used potentially to transport high Z atoms into tumor cell DNA for AET (Auger Electron Therapy). In order to assess the uptake of these agents into cells, the role of the LDL receptor in the intracellular accumulation of BOPP and In-BOPP was investigated. Pre-incubation of V-79 Chinese hamster cells in medium containing delipidized fetal bovine serum (FBS) markedly increased the subsequent uptake of intracellular boron transported by both BOPP and In-BOPP when compared with cells that had been pre-incubated with medium containing 10% normal FBS (lipidized). The increased uptake was characterized by elevated levels of receptor, and greater affinity was shown for both BOPP and In-BOPP, although less marked with the latter. Positive cooperativity was demonstrated by sigmoid saturation curves, Scatchard analysis and Hill plots. Increasing the amount of LDL in the incubation medium had a relatively small effect on the total accumulation of either indium or boron atoms inside the cell. Furthermore, chemical acetylation of LDL did not decrease the intracellular uptake of either boron or indium transported by BOPP or In-BOPP. It is thus concluded that BOPP and In-BOPP preferentially enter the cells directly by way of the LDL receptor and that only a small fraction of these molecules are transported into the cells indirectly using serum LDLs as their carriers. These data suggest a novel way of bringing greater amounts of boron and indium (and perhaps other agents) into tissues. Porphyrins can be used to transport different agents into tumor cells because they are tumor affinic molecules. Tumors express a higher number of LDL receptors than do most normal tissues

  12. Cation-Coupled Bicarbonate Transporters

    OpenAIRE

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2014-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 ...

  13. Cation disorder in shocked orthopyroxene.

    Science.gov (United States)

    Dundon, R. W.; Hafner, S. S.

    1971-01-01

    The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

  14. Cation coordination in oxychloride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J A [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States); Holland, D [Physics Department, Warwick University, Coventry (United Kingdom); Bland, J [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom); Johnson, C E [Physics Department, Northern Illinois University, DeKalb, IL (United States); Thomas, M F [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom)

    2003-02-19

    Glasses containing mixtures of cations and anions of nominal compositions [Sb{sub 2}O{sub 3}]{sub x} - [ZnCl{sub 2}]{sub 1-x} where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb){sub 2}(OZn)] and [Zn(ClZn){sub 2}(OSb){sub 2}].

  15. Cation coordination in oxychloride glasses

    International Nuclear Information System (INIS)

    Johnson, J A; Holland, D; Bland, J; Johnson, C E; Thomas, M F

    2003-01-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb 2 O 3 ] x - [ZnCl 2 ] 1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb) 2 (OZn)] and [Zn(ClZn) 2 (OSb) 2

  16. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  17. Assembly of individual TiO2-C60/porphyrin hybrid nanoparticles for enhancement of photoconversion efficiency

    International Nuclear Information System (INIS)

    Jang, Jae Kwon; Park, Se Ho; Song, Hyunjoon; Park, Joon T; Kim, Chulwoo; Ko, Jaejung; Seo, Won Seok

    2011-01-01

    Rational organization of porphyrin and C 60 on the electrode surface in photovoltaic structures is essential to yield high quantum efficiency. In the present work, individual TiO 2 nanoparticles were modified by introducing C 60 and porphyrin units on the surface, and then electrophoretically deposited on an ITO/SnO 2 electrode. The morphology of the photoactive layer on the electrode was significantly different from that of the layer produced as a result of separate deposition of C 60 and porphyrin. The maximum incident photon to current efficiency of the resulting electrode approached 88% at 410 nm, which is the highest value among molecule-based photovoltaic cells reported to date. This indicates that molecular assembly of the C 60 and porphyrin units on the individual nanoparticles through strong chemical attachment is a key factor in improving effective electron transfer between the photoactive units and the electrodes.

  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

  19. 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.

  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. 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

  2. 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.

  3. Engineering of Porphyrin Molecules for Use as Effective Cathode Interfacial Modifiers in Organic Solar Cells of Enhanced Efficiency and Stability.

    Science.gov (United States)

    Tountas, Marinos; Verykios, Apostolis; Polydorou, Ermioni; Kaltzoglou, Andreas; Soultati, Anastasia; Balis, Nikolaos; Angaridis, Panagiotis A; Papadakis, Michael; Nikolaou, Vasilis; Auras, Florian; Palilis, Leonidas C; Tsikritzis, Dimitris; Evangelou, Evangelos K; Gardelis, Spyros; Koutsoureli, Matroni; Papaioannou, George; Petsalakis, Ioannis D; Kennou, Stella; Davazoglou, Dimitris; Argitis, Panagiotis; Falaras, Polycarpos; Coutsolelos, Athanassios G; Vasilopoulou, Maria

    2018-06-06

    In the present work, we effectively modify the TiO 2 electron transport layer of organic solar cells with an inverted architecture using appropriately engineered porphyrin molecules. The results show that the optimized porphyrin modifier bearing two carboxylic acids as the anchoring groups and a triazine electron-withdrawing spacer significantly reduces the work function of TiO 2 , thereby reducing the electron extraction barrier. Moreover, the lower surface energy of the porphyrin-modified substrate results in better physical compatibility between the latter and the photoactive blend. Upon employing porphyrin-modified TiO 2 electron transport layers in PTB7:PC 71 BM-based organic solar cells we obtained an improved average power conversion efficiency up to 8.73%. Importantly, porphyrin modification significantly increased the lifetime of the devices, which retained 80% of their initial efficiency after 500 h of storage in the dark. Because of its simplicity and efficacy, this approach should give tantalizing glimpses and generate an impact into the potential of porphyrins to facilitate electron transfer in organic solar cells and related devices.

  4. Differential Antioxidant Responses and Perturbed Porphyrin Biosynthesis after Exposure to Oxyfluorfen and Methyl Viologen in Oryza sativa

    Directory of Open Access Journals (Sweden)

    Nhi-Thi Pham

    2015-07-01

    Full Text Available We compared antioxidant responses and regulation of porphyrin metabolism in rice plants treated with oxyfluorfen (OF or methyl viologen (MV. Plants treated with MV exhibited not only greater increases in conductivity and malondialdehyde but also a greater decline in Fv/Fm, compared to plants treated with OF. MV-treated plants had greater increases in activities of superoxide dismutase (SOD and catalase (CAT as well as transcript levels of SODA and CATA than OF-treated plants after 28 h of the treatments, whereas increases in ascorbate peroxidase (APX activity and transcript levels of APXA and APXB were greater in OF-treated plants. Both OF- and MV-treated plants resulted in not only down-regulation of most genes involved in porphyrin biosynthesis but also disappearance of Mg-porphyrins during the late stage of photooxidative stress. By contrast, up-regulation of heme oxygenase 2 (HO2 is possibly part of an efficient antioxidant response to compensate photooxidative damage in both treatments. Our data show that down-regulated biosynthesis and degradation dynamics of porphyrin intermediates have important roles in photoprotection of plants from perturbed porphyrin biosynthesis and photosynthetic electron transport. This study suggests that porphyrin scavenging as well as strong antioxidative activities are required for mitigating reactive oxygen species (ROS production under photooxidative stress caused by OF and MV.

  5. Differential Antioxidant Responses and Perturbed Porphyrin Biosynthesis after Exposure to Oxyfluorfen and Methyl Viologen in Oryza sativa.

    Science.gov (United States)

    Pham, Nhi-Thi; Kim, Jin-Gil; Jung, Sunyo

    2015-07-21

    We compared antioxidant responses and regulation of porphyrin metabolism in rice plants treated with oxyfluorfen (OF) or methyl viologen (MV). Plants treated with MV exhibited not only greater increases in conductivity and malondialdehyde but also a greater decline in Fv/Fm, compared to plants treated with OF. MV-treated plants had greater increases in activities of superoxide dismutase (SOD) and catalase (CAT) as well as transcript levels of SODA and CATA than OF-treated plants after 28 h of the treatments, whereas increases in ascorbate peroxidase (APX) activity and transcript levels of APXA and APXB were greater in OF-treated plants. Both OF- and MV-treated plants resulted in not only down-regulation of most genes involved in porphyrin biosynthesis but also disappearance of Mg-porphyrins during the late stage of photooxidative stress. By contrast, up-regulation of heme oxygenase 2 (HO2) is possibly part of an efficient antioxidant response to compensate photooxidative damage in both treatments. Our data show that down-regulated biosynthesis and degradation dynamics of porphyrin intermediates have important roles in photoprotection of plants from perturbed porphyrin biosynthesis and photosynthetic electron transport. This study suggests that porphyrin scavenging as well as strong antioxidative activities are required for mitigating reactive oxygen species (ROS) production under photooxidative stress caused by OF and MV.

  6. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    Science.gov (United States)

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  7. Electronic spectra of astrophysically interesting cations

    Energy Technology Data Exchange (ETDEWEB)

    Maier, John P., E-mail: j.p.maier@unibas.ch; Rice, Corey A., E-mail: j.p.maier@unibas.ch; Mazzotti, Fabio J., E-mail: j.p.maier@unibas.ch; Johnson, Anatoly, E-mail: j.p.maier@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstr. 80, CH-4056 Basel (Switzerland)

    2015-01-22

    The electronic spectra of polyacetylene cations were recorded at 20K in the laboratory in an ion trap instrument. These can then be compared with diffuse interstellar band (DIB) absorptions. Examination of recently published data shows that the attribution of a weak DIB at ∼506.9 nm to diacetylene cation is not justified. Study of the higher excited electronic states of polyacetylene cations shows that their widths can still be sufficiently narrow for consideration as DIB carriers.

  8. Uranium isotope separation using styrene cation exchangers

    International Nuclear Information System (INIS)

    Kahovec, J.

    1980-01-01

    The separation of 235 U and 238 U isotopes is carried out either by simple isotope exchange in the system uranium-cation exchanger (sulphonated styrene divinylbenzene resin), or by combination of isotope exchange in a uranium-cation exchanger (Dowex 50, Amberlite IR-120) system and a chemical reaction. A review is presented of elution agents used, the degree of cation exchanger cross-linking, columns length, and 235 U enrichment. The results are described of the isotope effect study in a U(IV)-U(VI)-cation exchanger system conducted by Japanese and Romanian authors (isotope exchange kinetics, frontal analysis, reverse (indirect) frontal analysis). (H.S.)

  9. Cation-π interactions in structural biology

    OpenAIRE

    Gallivan, Justin P.; Dougherty, Dennis A.

    1999-01-01

    Cation-pi interactions in protein structures are identified and evaluated by using an energy-based criterion for selecting significant sidechain pairs. Cation-pi interactions are found to be common among structures in the Protein Data Bank, and it is clearly demonstrated that, when a cationic sidechain (Lys or Arg) is near an aromatic sidechain (Phe, Tyr, or Trp), the geometry is biased toward one that would experience a favorable cation-pi interaction. The sidechain of Arg is more likely tha...

  10. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    and the expulsion of anions; a broad anodic peak centered at ca. - 0.5 V representing the expulsion of cations; and a second broad peak at +0.2 to +0.5 V corresponding to anions being inserted. Although the motion of cations is the most important, as expected, there is a significant anion contribution, thereby...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  11. Communication: Charge-transfer rate constants in zinc-porphyrin-porphyrin-derived dyads: A Fermi golden rule first-principles-based study

    International Nuclear Information System (INIS)

    Manna, Arun K.; Dunietz, Barry D.

    2014-01-01

    We investigate photoinduced charge transfer (CT) processes within dyads consisting of porphyrin derivatives in which one ring ligates a Zn metal center and where the rings vary by their degree of conjugation. Using a first-principles approach, we show that molecular-scale means can tune CT rates through stabilization affected by the polar environment. Such means of CT tuning are important for achieving high efficiency optoelectronic applications using organic semiconducting materials. Our fully quantum mechanical scheme is necessary for reliably modeling the CT process across different regimes, in contrast to the pervading semi-classical Marcus picture that grossly underestimates transfer in the far-inverted regime

  12. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  13. Porphyrin synthesized from cashew nut shell liquid as part of a novel superparamagnetic fluorescence nanosystem

    Energy Technology Data Exchange (ETDEWEB)

    Clemente, C. S.; Ribeiro, V. G. P.; Sousa, J. E. A.; Maia, F. J. N.; Barreto, A. C. H. [Universidade Federal do Ceara, Laboratorio de Produtos e Tecnologia em Processos (LPT) (Brazil); Andrade, N. F. [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Denardin, J. C. [Universidad de Santiago de Chile (USACH), Departamento de Fisica (Chile); Mele, G. [Universita del Salento, Dipartimento di Ingegneria dell' Innovazione (Italy); Carbone, L. [NNL, Istituto Nanoscienze UOS Lecce (Italy); Mazzetto, S. E. [Universidade Federal do Ceara, Laboratorio de Produtos e Tecnologia em Processos (LPT) (Brazil); Fechine, P. B. A., E-mail: fechine@ufc.br [Universidade Federal do Ceara (UFC), Grupo de Quimica de Materiais Avancados (GQMAT), Departamento de Quimica Analitica e Fisico-Quimica (Brazil)

    2013-06-15

    Magnetic Fe{sub 3}O{sub 4} nanoparticles with average size approximately 11 nm were first oleic acid coated to interact with the meso-porphyrin derivative from CNSL. This procedure produced a novel superparamagnetic fluorescent nanosystem (SFN) linked by van der Waals interactions. This system was characterized by transmission electron microscope, infrared spectroscopy, thermogravimetric analysis, magnetic measurements, UV-Vis absorption, and fluorescence emission measurements. These results showed that SFN has good thermal stability, excellent magnetization, and nanosized dimensions ({approx}13 nm). It exhibited emission peaks at 668 and 725 nm with a maximum emission at 467 nm of excitation wavelength. The type of interaction between porphyrin and magnetic nanoparticles allowed to obtain a material with interesting optical properties which might be used as an imaging agent for contrast in cells as well as heterogeneous photocatalysis.

  14. Computational screening of functionalized zinc porphyrins for dye sensitized solar cells

    DEFF Research Database (Denmark)

    Ørnsø, Kristian Baruël; García Lastra, Juan Maria; Thygesen, Kristian Sommer

    2013-01-01

    separation, and high output voltage. Here we demonstrate an extensive computational screening of zinc porphyrins functionalized with electron donating side groups and electron accepting anchoring groups. The trends in frontier energy levels versus side groups are analyzed and a no-loss DSSC level alignment...... quality is estimated. Out of the initial 1029 molecules, we find around 50 candidates with level alignment qualities within 5% of the optimal limit. We show that the level alignment of five zinc porphyrin dyes which were recently used in DSSCs with high efficiencies can be further improved by simple side......An efficient dye sensitized solar cell (DSSC) is one possible solution to meet the world's rapidly increasing energy demands and associated climate challenges. This requires inexpensive and stable dyes with well-positioned frontier energy levels for maximal solar absorption, efficient charge...

  15. A supramolecular miktoarm star polymer based on porphyrin metal complexation in water.

    Science.gov (United States)

    Hou, Zhanyao; Dehaen, Wim; Lyskawa, Joël; Woisel, Patrice; Hoogenboom, Richard

    2017-07-25

    A novel supramolecular miktoarm star polymer was successfully constructed in water from a pyridine end-decorated polymer (Py-PmDEGA) and a metalloporphyrin based star polymer (ZnTPP-(PEG) 4 ) via metal-ligand coordination. The Py-PmDEGA moiety was prepared via a combination of reversible addition-fragmentation chain transfer polymerization (RAFT) and subsequent aminolysis and Michael addition reactions to introduce the pyridine end-group. The ZnTPP(PEG) 4 star-polymer was synthesized by the reaction between tetrakis(p-hydroxyphenyl)porphyrin and toluenesulfonyl-PEG, followed by insertion of a zinc ion into the porphyrin core. The formation of a well-defined supramolecular AB 4 -type miktoarm star polymer was unambiguously demonstrated via UV-Vis spectroscopic titration, isothermal titration calorimetry (ITC) and diffusion ordered NMR spectroscopy (DOSY).

  16. Selective C-H Halogenation with a Highly Fluorinated Manganese Porphyrin.

    Science.gov (United States)

    Li, Gang; Dilger, Andrew K; Cheng, Peter T; Ewing, William R; Groves, John T

    2018-01-26

    The selective C-H functionalization of aliphatic molecules remains a challenge in organic synthesis. While radical chain halogenation reactions provide efficient access to many halogenated molecules, the use of typical protocols for the selective halogenation of electron-deficient and strained aliphatic molecules is rare. Herein, we report selective C-H chlorination and fluorination reactions promoted by an electron-deficient manganese pentafluorophenyl porphyrin catalyst, Mn(TPFPP)Cl. This catalyst displays superior properties for the aliphatic halogenation of recalcitrant, electron-deficient, and strained substrates with unique regio- and stereoselectivity. UV/Vis analysis during the course of the reaction indicated that an oxo-Mn V species is responsible for hydrogen-atom abstraction. The observed stereoselectivity results from steric interactions between the bulky porphyrin ligand and the intermediate substrate radical in the halogen rebound step. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Tunneling electron induced molecular electroluminescence from individual porphyrin J-aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Qiushi; Zhang, Chao; Zhang, Yang, E-mail: zhyangnano@ustc.edu.cn, E-mail: zcdong@ustc.edu.cn; Zhang, Yao; Liao, Yuan; Dong, Zhenchao, E-mail: zhyangnano@ustc.edu.cn, E-mail: zcdong@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-07-27

    We investigate molecular electroluminescence from individual tubular porphyrin J-aggregates on Au(111) by tunneling electron excitations in an ultrahigh-vacuum scanning tunneling microscope (STM). High-resolution STM images suggest a spiral tubular structure for the porphyrin J-aggregate with highly ordered “brickwork”-like arrangements. Such aggregated nanotube is found to behave like a self-decoupled molecular architecture and shows red-shifted electroluminescence characteristics of J-aggregates originated from the delocalized excitons. The positions of the emission peaks are found to shift slightly depending on the excitation sites, which, together with the changes in the observed spectral profiles with vibronic progressions, suggest a limited exciton coherence number within several molecules. The J-aggregate electroluminescence is also found unipolar, occurring only at negative sample voltages, which is presumably related to the junction asymmetry in the context of molecular excitations via the carrier injection mechanism.

  18. Effects of radiation and porphyrin on mitosis and chromosomes in human hematopoietic cell lines

    International Nuclear Information System (INIS)

    Tan, J.C.; Huang, C.C.; Fiel, R.J.

    1976-01-01

    The effect on mitosis of a human hematopoietic cell line RPMI-1788 treated with a metal chelate (Zn ++ ) of meso-tetra (p-carboxyphenyl) porphine (Zn-TCPP) alone at various concentrations or in combination with gamma-irradiation at various doses were studied. The results showed that both Zn-TCPP and radiation were effective in interfering with normal mitosis and that the effect of radiation was relatively more effective. Data also suggest interacting effects between Zn-TCPP and gamma-irradiation. At low doses of radiation, Zn-TCPP potentiated the effect of radiation. The reverse seemed to be true at a high dose of radiation. The effects of two porphyrins (Zn-TCPP and hematoporphyrin) and radiation on chromosomes were also studied. Chromosomal aberrations characteristic of radiation were observed. The porphyrins were found not to be effective chromosome-breaking agents under the experimental conditions tested

  19. 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.

  20. Radiolabeled porphyrin versus gallium-67 citrate for the detection of human melanoma in athymic mice

    International Nuclear Information System (INIS)

    Maric, N.; Chan, S. Ming; Hoffer, P.B.; Duray, P.

    1987-01-01

    We performed the biodistribution and imaging studies of 111 In and 67 Ga labeled tetra(4-N-methylpyridyl) porphine, (T4NMPYP), and compared it to that of 67 Ga citrate in athymic mice bearing a human melanoma xenograft. The biodistribution results of both 111 In and 67 Ga labeled T4NMPYP (3, 6, 24, and 48 hours) were similar but differed from that of 67 Ga citrate (48 hours). The optimum tumor uptake of both radiolabeled porphyrins was at 6 hours postinjection and was lower than the tumor uptake of 67 Ga citrate at 48 hours postinjection. Kidney was the only organ showing higher uptake of radiolabeled porphyrin compared to that of 67 Ga citrate. The imaging studies performed with 111 In T4NMPYP and 67 Ga citrate correspond to the biodistribution results. Osteomyelitis present in one mouse showed good localization of 111 In T4NMPYP. 15 refs., 3 figs., 5 tabs

  1. Porphyrin-sensitized solar cells: systematic molecular optimization, coadsorption and cosensitization.

    Science.gov (United States)

    Song, Heli; Liu, Qingyun; Xie, Yongshu

    2018-02-15

    As a promising low-cost solar energy conversion technique, dye-sensitized solar cells have undergone spectacular development since 1991. For practical applications, improvement of power conversion efficiency has always been one of the major research topics. Porphyrins are outstanding sensitizers endowed with strong sunlight harvesting ability in the visible region and multiple reaction sites available for functionalization. However, judicious molecular design in consideration of light-harvest, energy levels, operational dynamics, adsorption geometry and suppression of back reactions is specifically required for achieving excellent photovoltaic performance. This feature article highlights some of the recently developed porphyrin sensitizers, especially focusing on the systematic dye structure optimization approach in combination with coadsorption and cosensitization methods in pursuing higher efficiencies. Herein, we expect to provide more insights into the structure-performance correlation and molecular engineering strategies in a stepwise manner.

  2. Diagnostic use of blood porphyrin and radiographic changes in lead exposure in goats

    International Nuclear Information System (INIS)

    Swarup, D.; Maiti, S.K.; Dwivedi, S.K.

    1990-01-01

    Blood porphyrin, hematological examination and radiographic changes were evaluated for the detection of lead intoxication in goats given daily po doses of 10, 15 and 20 mg lead acetate (5.43, 8.15 and 10.86 mg lead)/kg body weight for 30, 30 and 31 days, or a total of 91 days. Blood porphyrin was found a sensitive indicator with direct correlation (r = 0.976) to blood lead concentration. Basophilic stippling was not seen in the lead-exposed goats. Radiopaque bands developed at the distal metaphysis of the radius in 7 of the 12 lead-exposed goats at day 30. The usefulness of this sign for the diagnosis of lead exposure in goats requires further investigation

  3. Effect of ferrocene-substituted porphyrin RL-91 on Candida albicans biofilm formation.

    Science.gov (United States)

    Lippert, Rainer; Vojnovic, Sandra; Mitrovic, Aleksandra; Jux, Norbert; Ivanović-Burmazović, Ivana; Vasiljevic, Branka; Stankovic, Nada

    2014-08-01

    Ferrocene-substituted porphyrin RL-91 exhibits antifungal activity against opportune human pathogen Candida albicans. RL-91 efficiently inhibits growth of both planktonic C. albicans cells and cells within biofilms without photoactivation. The minimal inhibitory concentration for plankton form (PMIC) was established to be 100 μg/mL and the same concentration killed 80% of sessile cells in the mature biofilm (SMIC80). Furthermore PMIC of RL-91 efficiently prevents C. albicans biofilm formation. RL-91 is cytotoxic for human fibroblasts in vitro in concentration of 10 μg/mL, however it does not cause hemolysis in concentrations of up to 50 μg/mL. These findings open possibility for application of RL-91 as an antifungal agent for external antibiofilm treatment of medical devices as well as a scaffold for further development of porphyrin based systemic antifungals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Biomimetic oxidation of piperine and piplartine catalyzed by iron(III) and manganese(III) porphyrins.

    Science.gov (United States)

    Schaab, Estela Hanauer; Crotti, Antonio Eduardo Miller; Iamamoto, Yassuko; Kato, Massuo Jorge; Lotufo, Letícia Veras Costa; Lopes, Norberto Peporine

    2010-01-01

    Synthetic metalloporphyrins, in the presence of monooxygen donors, are known to mimetize various reactions of cytochrome P450 enzymes systems in the oxidation of drugs and natural products. The oxidation of piperine and piplartine by iodosylbenzene using iron(III) and manganese(III) porphyrins yielded mono- and dihydroxylated products, respectively. Piplartine showed to be a more reactive substrate towards the catalysts tested. The structures of the oxidation products were proposed based on electrospray ionization tandem mass spectrometry.

  5. Ion pair recognition by Zn-porphyrin/crown ether conjugates: visible sensing of sodium cyanide.

    Science.gov (United States)

    Kim, Yeon-Hwan; Hong, Jong-In

    2002-03-07

    Synthesis and complexation behavior of ditopic neutral receptors composed of both a Lewis-acidic binding site (zinc porphyrin moiety) and a Lewis-basic binding site (crown ether moiety) are reported; the receptors bound only NaCN in a ditopic fashion with a color change, and in contrast other sodium salts bound to the receptors in a monotopic fashion without a color change.

  6. Designing Porphyrinic Covalent Organic Frameworks for the Photodynamic Inactivation of Bacteria

    Czech Academy of Sciences Publication Activity Database

    Hynek, Jan; Zelenka, J.; Rathouský, Jiří; Kubát, Pavel; Ruml, T.; Demel, Jan; Lang, Kamil

    2018-01-01

    Roč. 10, č. 10 (2018), s. 8527-8535 ISSN 1944-8244 R&D Projects: GA ČR(CZ) GA16-15020S Institutional support: RVO:61388980 ; RVO:61388955 Keywords : antibacterial coating * biofilm * covalent organic framework * photodynamic * porphyrin * singlet oxygen Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Inorganic and nuclear chemistry; Physical chemistry (UFCH-W) Impact factor: 7.504, year: 2016

  7. Thiacalix[4]arene–porphyrin conjugates with high selectivity towards fullerene C70

    Czech Academy of Sciences Publication Activity Database

    Kundrát, O.; Káš, M.; Tkadlecová, M.; Lang, Kamil; Cvačka, Josef; Stibor, I.; Lhoták, P.

    2007-01-01

    Roč. 48, č. 38 (2007), s. 6620-6623 ISSN 0040-4039 R&D Projects: GA MŠk ME 857 Grant - others:GA MŠk(CZ) OC 134 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40550506 Keywords : porphyrin * thiacalixarenes * derivatives Subject RIV: CA - Inorganic Chemistry Impact factor: 2.615, year: 2007

  8. Enhanced magneto-optical SPR platform for amine sensing based on Zn porphyrin dimers

    OpenAIRE

    Manera, M. G.; Ferreiro-Vila, E.; Garcia-Martin, J. M.; Cebollada, A.; Garcia-Martin, A.; Giancane, G.; Valli, L.; Rella, R.

    2013-01-01

    Ethane-bridged Zn porphyrins dimers (ZnPP) have been deposited by Langmuir-Schäfer (LS) deposition technique onto proper transducer layers for surface plasmon resonance (SPR) and magneto-optical surface plasmon resonance (MO-SPR) characterization techniques performed in controlled atmosphere. This last tool has emerged as a novel and very performing sensing technique using as transducer layers a combination of noble and magnetic layers deposited onto glass substrates. A magnetic actuation all...

  9. Response of the oral mucosa to porphyrin mediated boron neutron capture therapy

    International Nuclear Information System (INIS)

    Morris, G.M.

    2003-01-01

    Pre-clinical studies are now in progress to develop boron neutron capture therapy (BNCT) modalities for the treatment of head and neck carcinomas. BNCT is a bimodal therapy which involves the administration of a boron-10 enriched compound, that accumulates preferentially in tumours, prior to irradiation with low energy neutrons. These neutrons are captured by boron-10 atoms to produce a highly localised radiation exposure. More recently, it has been demonstrated that various boronated porphyrins can target a variety of tumours. Of the porphyrins evaluated to date, copper tetracarboranylphenyl porphyrin (CuTCPH) is a strong candidate for potential clinical evaluation. It has extremely high specificity for a variety of tumour models. Therapeutic efficacy of CuTCPH mediated BNCT has been demonstrated in pre-clinical studies using the murine EMT-6 carcinoma model. In the present investigation the response of the oral mucosa to CuTCPH mediated boron neutron capture (BNC) irradiation was assessed using a standard rat model (ventral tongue). Single exposure irradiation was carried out on the thermal neutron beam at the Brookhaven Medical Research Reactor, at 3 days after the final injection of the boronated porphyrin. The impact of CuTCPH mediated BNC irradiation on oral mucosa at therapeutically effective exposure times, assessed using the ventral tongue model, was minimal. This was primarily due to the fact that blood boron levels (from CuTCPH) were very low at the time of irradiation. Analysis of the dose-effect data for CuTCPH gave a compound biological effectiveness (CBE) factor of 2.5. It can be concluded that, although, the CBE factor (calculated using blood boron concentrations) was relatively high, CuTCPH mediated BNC irradiation should not cause significant damage at clinically relevant radiation doses. This is because blood boron levels would be very low at the time of irradiation

  10. Nanoparticles with Embedded Porphyrin Photosensitizers for Photooxidation Reactions and Continuous Oxygen Sensing

    Czech Academy of Sciences Publication Activity Database

    Kubát, Pavel; Henke, P.; Berzediová, V.; Štěpánek, M.; Lang, Kamil; Mosinger, Jiří

    2017-01-01

    Roč. 9, č. 41 (2017), s. 36229-36238 ISSN 1944-8244 R&D Projects: GA ČR(CZ) GA16-15020S Institutional support: RVO:61388955 ; RVO:61388980 Keywords : photooxidation * polystyrene nanoparticles * porphyrins Subject RIV: CF - Physical ; Theoretical Chemistry; CA - Inorganic Chemistry (UACH-T) OBOR OECD: Physical chemistry; Inorganic and nuclear chemistry (UACH-T) Impact factor: 7.504, year: 2016

  11. Porphyrinic supramolecular daisy chains incorporating pillar[5]arene-viologen host-guest interactions

    KAUST Repository

    Fathalla, Maher; Strutt, Nathan; Srinivasan, Sampath; Katsiev, Khabiboulakh; Hartlieb, Karel J.; Bakr, Osman; Stoddart, J. Fraser

    2015-01-01

    A porphyrin functionalised with pillar[5]arene and a viologen at its 5- and 15-meso positions assembles in a head-to-tail manner, producing linear supramolecular daisy chains in dichloromethane. At high concentrations, it forms an organogel which has been investigated by electron microscopy and rheological measurements, paving the way for the preparation of other functional supramolecular assemblies which harness viologen"⊂" pillararene host-guest interactions.

  12. C-84 Selective Porphyrin Macrocycle with an Adaptable Cavity Constructed Through Alkyne Metathesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C. X.; Long, H.; Zhang, W.

    2012-06-21

    A bisporphyrin macrocycle was constructed from a porphyrin-based diyne monomer in one step through alkyne metathesis. The fullerene binding studies (C{sub 60}, C{sub 70} and C{sub 84}) showed the highest binding affinity of the macrocycle for C{sub 84}, which is in great contrast to its bisporphyrin four-armed cage analogue that showed the strongest binding with C{sub 70}.

  13. Porphyrinic supramolecular daisy chains incorporating pillar[5]arene-viologen host-guest interactions

    KAUST Repository

    Fathalla, Maher

    2015-05-18

    A porphyrin functionalised with pillar[5]arene and a viologen at its 5- and 15-meso positions assembles in a head-to-tail manner, producing linear supramolecular daisy chains in dichloromethane. At high concentrations, it forms an organogel which has been investigated by electron microscopy and rheological measurements, paving the way for the preparation of other functional supramolecular assemblies which harness viologen"⊂" pillararene host-guest interactions.

  14. Nanoparticles with Embedded Porphyrin Photosensitizers for Photooxidation Reactions and Continuous Oxygen Sensing

    Czech Academy of Sciences Publication Activity Database

    Kubát, Pavel; Henke, P.; Berzediová, V.; Štěpánek, M.; Lang, Kamil; Mosinger, Jiří

    2017-01-01

    Roč. 9, č. 41 (2017), s. 36229-36238 ISSN 1944-8244 R&D Projects: GA ČR(CZ) GA16-15020S Institutional support: RVO:61388955 ; RVO:61388980 Keywords : photooxidation * polystyrene nanoparticles * porphyrins Subject RIV: CF - Physical ; Theoretical Chemistry ; CA - Inorganic Chemistry (UACH-T) OBOR OECD: Physical chemistry ; Inorganic and nuclear chemistry (UACH-T) Impact factor: 7.504, year: 2016

  15. Glycol porphyrin derivatives and temoporfin elicit resistance to photodynamic therapy by different mechanisms

    Czech Academy of Sciences Publication Activity Database

    Králová, Jarmila; Kolář, Michal; Kahle, Michal; Truksa, Jaroslav; Lettlová, Sandra; Balusiková, K.; Bartůněk, Petr

    2017-01-01

    Roč. 7, Mar 15 (2017), č. článku 44497. ISSN 2045-2322 R&D Projects: GA MŠk LO1220 Institutional support: RVO:68378050 ; RVO:86652036 Keywords : Glycol porphyrin derivates * chemotherapy * cancer * multidrug resistance Subject RIV: EB - Genetics ; Molecular Biology; EB - Genetics ; Molecular Biology (BTO-N) OBOR OECD: Biochemistry and molecular biology; Biochemistry and molecular biology (BTO-N) Impact factor: 4.259, year: 2016

  16. Supramolecular tetracluster-cobalt porphyrin: a four-electron transfer catalyst for dioxygen reduction

    International Nuclear Information System (INIS)

    Winnischofer, Herbert; Otake, Vesper Yoshiyuki; Dovidauskas, Sergio; Nakamura, Marcelo; Toma, Henrique Eisi; Araki, Koiti

    2004-01-01

    Electrocatalysis by CoTCP {CoTCP meso-tetrakis(4-pyridyl)porphynatocobalt(III)} coordinated to four [Ru 3 (μ 3 -O)(μ 2 -CH 3 CO 2 ) 6 (py) 2 ] + complexes in the four-electron reduction of dioxygen, has been unequivocally demonstrated in this work by using two types of electrostatically assembled films of CoTCP and anionic zinc or free-base meso-tetrakis(4-sulfonatophenyl)porphyrins (ZnTPPS or H 2 TPPS), as well as, by employing different electrode materials. An enhanced electrocatalytic activity has been observed, in spite of the fact that the typical bis-coordination of dioxygen to two cobalt porphyrin sites is precluded in such CoTCP/ZnTPPS or CoTCP/H 2 TPPS bilayered films. In addition, negligible ring currents have been observed in ring-disk voltammetry measurements, yielding straight Levich and Koutecky-Levich plots, whose slopes approached the theoretical 4e - curve in air, or in O 2 saturated solutions (pH 3-5). The use of gold instead of glassy carbon (GC) electrodes has not also significantly perturbed the mechanism. By ruling out any influence from the electrode materials, a well known critical point in the catalysis by cobalt porphyrins, the results have shown that CoTCP is acting as a four-electron transfer catalyst for dioxygen reduction. Also, by excluding the possibility of bis-coordination of dioxygen, it was shown that the electronic and supramolecular effects exerted by the peripheral ruthenium cluster complexes should be triggering the four-electron catalytic activity of the cobalt porphyrin center

  17. Interaction of porphyrin and sapphyrin macrocycles with nucleobases and nucleosides. Spectroscopic, quantum chemical and chromatographic investigation

    Czech Academy of Sciences Publication Activity Database

    Záruba, K.; Tománková, Z.; Sýkora, D.; Charvátová, J.; Kavenová, I.; Bouř, Petr; Matějka, P.; Fähnrich, J.; Volka, K.; Král, V.

    2001-01-01

    Roč. 437, - (2001), s. 39-53 ISSN 0003-2670 R&D Projects: GA ČR GA203/01/0031; GA MŠk VS97135; GA ČR GV301/98/K042 Grant - others:HHMI(US) 75195-541101 Institutional research plan: CEZ:AV0Z4055905 Keywords : HPLC * porphyrin Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.073, year: 2001

  18. Facile one-pot synthesis of porphyrin based porous polymer networks (PPNs) as biomimetic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zou, LF; Feng, DW; Liu, TF; Chen, YP; Fordham, S; Yuan, S; Tian, J; Zhou, HC

    2015-01-01

    Stable porphyrin based porous polymer networks, PPN-23 and PPN-24, have been synthesized through a facile one-pot approach by the aromatic substitution reactions of pyrrole and aldehydes. PPN-24(Fe) shows high catalytic efficiency as a biomimetic catalyst in the oxidation reaction of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) in the presence of H2O2.

  19. Porphyrin-layered double hydroxide/polymer composites as novel ecological photoactive surfaces

    Czech Academy of Sciences Publication Activity Database

    Káfuňková, Eva; Lang, Kamil; Kubát, Pavel; Klementová, Mariana; Mosinger, Jiří; Šlouf, Miroslav; Troutier-Thuilliez, A. L.; Leroux, F.; Verney, V.; Taviot-Guého, Ch.

    2010-01-01

    Roč. 20, č. 42 (2010), s. 9423-9432 ISSN 0959-9428 R&D Projects: GA ČR GAP207/10/1447 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40400503; CEZ:AV0Z40500505 Keywords : porphyrins * nanoparticles * hydroxide/polymer composites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.101, year: 2010

  20. 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.

  1. Two-photon excitation of porphyrin-functionalized porous silicon nanoparticles for photodynamic therapy.

    Science.gov (United States)

    Secret, Emilie; Maynadier, Marie; Gallud, Audrey; Chaix, Arnaud; Bouffard, Elise; Gary-Bobo, Magali; Marcotte, Nathalie; Mongin, Olivier; El Cheikh, Khaled; Hugues, Vincent; Auffan, Mélanie; Frochot, Céline; Morère, Alain; Maillard, Philippe; Blanchard-Desce, Mireille; Sailor, Michael J; Garcia, Marcel; Durand, Jean-Olivier; Cunin, Frédérique

    2014-12-03

    Porous silicon nanoparticles (pSiNPs) act as a sensitizer for the 2-photon excitation of a pendant porphyrin using NIR laser light, for imaging and photodynamic therapy. Mannose-functionalized pSiNPs can be vectorized to MCF-7 human breast cancer cells through a mannose receptor-mediated endocytosis mechanism to provide a 3-fold enhancement of the 2-photon PDT effect. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Perylene anhydride fused porphyrins as near-infrared sensitizers for dye-sensitized solar cells

    KAUST Repository

    Jiao, Chongjun

    2011-07-15

    Two perylene anhydride fused porphyrins 1 and 2 have been synthesized and employed successfully in dye-sensitized solar cells (DSCs). Both compounds showed broad incident monochromatic photon-to-current conversion efficiency spectra covering the entire visible spectral region and even extending into the near-infrared (NIR) region up to 1000 nm, which is impressive for ruthenium-free dyes in DSCs. © 2011 American Chemical Society.

  3. Cationic polymers and their therapeutic potential

    NARCIS (Netherlands)

    Samal, S.K.; Dash, M.; van Vlierberghe, S.; Kaplan, D.; Chiellini, E.; van Blitterswijk, Clemens; Moroni, Lorenzo; Dubruel, P.

    2012-01-01

    The last decade has witnessed enormous research focused on cationic polymers. Cationic polymers are the subject of intense research as non-viral gene delivery systems, due to their flexible properties, facile synthesis, robustness and proven gene delivery efficiency. Here, we review the most recent

  4. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

    Full Text Available This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  5. Asymmetric Aminalization via Cation-Binding Catalysis

    DEFF Research Database (Denmark)

    Park, Sang Yeon; Liu, Yidong; Oh, Joong Suk

    2018-01-01

    Asymmetric cation-binding catalysis, in principle, can generate "chiral" anionic nucleophiles, where the counter cations are coordinated within chiral environments. Nitrogen-nucleophiles are intrinsically basic, therefore, its use as nucleophiles is often challenging and limiting the scope of the...

  6. Structural and energetic study of cation-π-cation interactions in proteins.

    Science.gov (United States)

    Pinheiro, Silvana; Soteras, Ignacio; Gelpí, Josep Lluis; Dehez, François; Chipot, Christophe; Luque, F Javier; Curutchet, Carles

    2017-04-12

    Cation-π interactions of aromatic rings and positively charged groups are among the most important interactions in structural biology. The role and energetic characteristics of these interactions are well established. However, the occurrence of cation-π-cation interactions is an unexpected motif, which raises intriguing questions about its functional role in proteins. We present a statistical analysis of the occurrence, composition and geometrical preferences of cation-π-cation interactions identified in a set of non-redundant protein structures taken from the Protein Data Bank. Our results demonstrate that this structural motif is observed at a small, albeit non-negligible frequency in proteins, and suggest a preference to establish cation-π-cation motifs with Trp, followed by Tyr and Phe. Furthermore, we have found that cation-π-cation interactions tend to be highly conserved, which supports their structural or functional role. Finally, we have performed an energetic analysis of a representative subset of cation-π-cation complexes combining quantum-chemical and continuum solvation calculations. Our results point out that the protein environment can strongly screen the cation-cation repulsion, leading to an attractive interaction in 64% of the complexes analyzed. Together with the high degree of conservation observed, these results suggest a potential stabilizing role in the protein fold, as demonstrated recently for a miniature protein (Craven et al., J. Am. Chem. Soc. 2016, 138, 1543). From a computational point of view, the significant contribution of non-additive three-body terms challenges the suitability of standard additive force fields for describing cation-π-cation motifs in molecular simulations.

  7. Synthesis, reactivity, and properties of N-fused porphyrin rhenium(I) tricarbonyl complexes.

    Science.gov (United States)

    Toganoh, Motoki; Ikeda, Shinya; Furuta, Hiroyuki

    2007-11-12

    The thermal reactions of N-fused tetraarylporphyrins or N-confused tetraarylporphyrins with Re2(CO)10 gave the rhenium(I) tricarbonyl complexes bearing N-fused porphyrinato ligands (4) in moderate to good yields. The rhenium complexes 4 are characterized by mass, IR, 1H, and 13C NMR spectroscopy, and the structures of tetraphenylporphynato complex 4a and its nitro derivative 15 are determined by X-ray single crystal analysis. The rhenium complexes 4 show excellent stability against heat, light, acids, bases, and oxidants. The aromatic substitution reactions of 4 proceed without a loss of the center metal to give the nitro (15), formyl (16), benzoyl (17), and cyano derivatives (19), regioselectively. In the electrochemical measurements for 4, one reversible oxidation wave and two reversible reduction waves are observed. Their redox potentials imply narrow HOMO-LUMO band gaps of 4 and are consistent with their electronic absorption spectra, in which the absorption edges exceed 1000 nm. Theoretical study reveals that the HOMO and LUMO of the rhenium complexes are exclusively composed of the N-fused porphyrin skeleton. Protonation of 4 takes place at the 21-position regioselectively, reflecting the high coefficient of the C21 atom in the HOMO orbital. The skeletal rearrangement reaction from N-confused porphyrin Re(I) complex (8) to N-fused porphyrin Re(I) complex (4) is suggested from the mechanistic study as well as DFT calculations.

  8. Synthesis, characterization, and nonlinear optical properties of graphene oxide functionalized with tetra-amino porphyrin

    International Nuclear Information System (INIS)

    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.

  9. Role of electrostatic complementarity between perylenediimide and porphyrin in highly stabilized GNA

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Yonggang [Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070 (China); Zhang, Qingye [Agricultural Bioinformatics Key Laboratory of Hubei Province, College of Informatics Huazhong Agricultural University, Wuhan 430070 (China); Li, Zibiao, E-mail: lizb@imre.a-star.edu.sg [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634 (Singapore); Chen, Hao, E-mail: hchenhao@mail.hzau.edu.cn [Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan 430070 (China)

    2017-01-01

    Relatively electron-deficient perylenediimide (PDI) and relatively electron-rich porphyrin (Por) were introduced into the middle of 16-mer glycol nucleic acid (GNA), and up to five consecutive chromophores were arranged in the zipper-like interstrand alternating fashion. Remarkable variation for the CD spectra ascribed to chromophores was observed, and bathochromic shift in the UV/Vis absorption region of chromophores occurred upon duplex formation. Interestingly, zipper-like heteroaggregates of chromophores inside had marvelous positive effects on the stabilization of the duplex, T{sub m} of Por-PDI-Por sandwich-type modified GNA duplex was increased by 24 °C in comparison with three A-T base pairs, moreover, Por-PDI-Por-PDI-Por interstrand modified GNA duplex was even stabilized by 25 °C in replacement of five A-T base pairs. The specificity of high duplex stability might be driven by the strong hydrophobic electrostatic complementarity between PDI and Por face-centered stacking. - Highlights: • Electrostatic complementarity between relatively electron-deficient perylenediimide and relatively electron-rich porphyrin • Zipper-like heteroaggregates of perylenediimide and porphyrin could stablize the GNA duplex significantly. • Chromophores can lead to remarkable variation for the CD spectra and bathochromic shift occurred upon duplex formation.

  10. 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.

  11. XAFS Debye-Waller Factors Temperature-Dependent Expressions for Fe+2-Porphyrin Complexes

    Science.gov (United States)

    Dimakis, Nicholas; Bunker, Grant

    2007-02-01

    We present an efficient and accurate method for directly calculating single and multiple scattering X-ray absorption fine structure (XAFS) thermal Debye-Waller factors for Fe+2 -porphiryn complexes. The number of multiple scattering Debye-Waller factors on metal porphyrin centers exceeds the number of available parameters that XAFS experimental data can support during fitting with simulated spectra. Using the Density Functional Theory (DFT) under the hybrid functional of X3LYP, phonon normal mode spectrum properties are used to express the mean square variation of the half-scattering path length for a Fe+2 -porphiryn complex as a function of temperature for the most important single and multiple scattering paths of the complex thus virtually eliminating them from the fitting procedure. Modeled calculations are compared with corresponding values obtained from DFT-built and optimized Fe+2 -porphyrin bis-histidine structure as well as from experimental XAFS spectra previously reported. An excellent agreement between calculated and reference Debye-Waller factors for Fe+2-porphyrins is obtained.

  12. 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

  13. In vivo photoacoustic tumor tomography using a quinoline-annulated porphyrin as NIR molecular contrast agent.

    Science.gov (United States)

    Luciano, Michael; Erfanzadeh, Mohsen; Zhou, Feifei; Zhu, Hua; Bornhütter, Tobias; Röder, Beate; Zhu, Quing; Brückner, Christian

    2017-01-25

    The synthesis and photophysical properties of a tetra-PEG-modified and freely water-soluble quinoline-annulated porphyrin are described. We previously demonstrated the ability of quinoline-annulated porphyrins to act as an in vitro NIR photoacoustic imaging (PAI) contrast agent. The solubility of the quinoline-annulated porphyrin derivative in serum now allowed the assessment of the efficacy of the PEGylated derivative as an in vivo NIR contrast agent for the PAI of an implanted tumor in a mouse model. A multi-fold contrast enhancement when compared to the benchmark dye ICG could be shown, a finding that could be traced to its photophysical properties (short triplet lifetimes, low fluorescence and singlet oxygen sensitization quantum yields). A NIR excitation wavelength of 790 nm could be used, fully taking advantage of the optical window of tissue. Rapid renal clearance of the dye was observed. Its straight-forward synthesis, optical properties with the possibility for further optical fine-tuning, nontoxicity, favorable elimination rates, and contrast enhancement make this a promising PAI contrast agent. The ability to conjugate the PAI chromophore with a fluorescent tag using a facile and general conjugation strategy was also demonstrated.

  14. Physical and photophysical properties of mixed double- and triple-decker sandwiches of porphyrins and phthalocyanines

    International Nuclear Information System (INIS)

    Salabert, Isabelle

    1995-01-01

    The study of electron transfer and charge recombination processes in various oligomers of porphyrins and phthalocyanines is reported. Our objective is to determine the nature of processes which compete with electron transfer in such Systems. The first part of this thesis is devoted to the study of mixed double- and triple-decker sandwich compounds of porphyrins and phthalocyanines of cerium and praseodymium. The charge transfer reaction and geminated recombination from excited complexes in solution and in sublimated film are investigated by time-resolved absorption spectroscopy with femtosecond time scale resolution. These results show the influence of the magnetic nature of the metal ion and of the relative position of the chromophores in the complex on the photophysical processes. The physical and photophysical properties of complexes formed by pairing in solution porphyrins and porphyrazines bearing oppositely charged substituent are reported in the second part. The formation of mixed aggregates of high order (2 to 5) is observed and their nature are spectrally characterized. The photoproducts issued from these complexes are extremely stable. (author) [fr

  15. Light-activated nanotube–porphyrin conjugates as effective antiviral agents

    International Nuclear Information System (INIS)

    Banerjee, Indrani; Douaisi, Marc P; Mondal, Dhananjoy; Kane, Ravi S

    2012-01-01

    Porphyrins have been used for photodynamic therapy (PDT) against a wide range of targets like bacteria, viruses and tumor cells. In this work, we report porphyrin-conjugated multi-walled carbon nanotubes (NT-P) as potent antiviral agents. Specifically, we used Protoporphyrin IX (PPIX), which we attached to acid-functionalized multi-walled carbon nanotubes (MWNTs). We decided to use carbon nanotubes as scaffolds because of their ease of recovery from a solution through filtration. In the presence of visible light, NT-P was found to significantly reduce the ability of Influenza A virus to infect mammalian cells. NT-P may be used effectively against influenza viruses with little or no chance of them developing resistance to the treatment. Furthermore, NT-P can be easily recovered through filtration which offers a facile strategy to reuse the active porphyrin moiety to its fullest extent. Thus NT-P conjugates represent a new approach for preparing ex vivo reusable antiviral agents. (paper)

  16. Iron(III) Fluorinated Porphyrins: Greener Chemistry from Synthesis to Oxidative Catalysis Reactions.

    Science.gov (United States)

    Rebelo, Susana L H; Silva, André M N; Medforth, Craig J; Freire, Cristina

    2016-04-12

    Iron(III) fluorinated porphyrins play a central role in the biomimetics of heme enzymes and enable cleaner routes to the oxidation of organic compounds. The present work reports significant improvements in the eco-compatibility of the synthesis of 5,10,15,20-tetrakis-pentafluorophenylporphyrin (H₂TPFPP) and the corresponding iron complex [Fe(TPFPP)Cl], and the use of [Fe(TPFPP)Cl] as an oxidation catalyst in green conditions. The preparations of H₂TPFPP and [Fe(TPFPP)Cl] typically use toxic solvents and can be made significantly greener and simpler using microwave heating and optimization of the reaction conditions. In the optimized procedure it was possible to eliminate nitrobenzene from the porphyrin synthesis and replace DMF by acetonitrile in the metalation reaction, concomitant with a significant reduction of reaction time and simplification of the purification procedure. The Fe(III)porphyrin is then tested as catalyst in the selective oxidation of aromatics at room temperature using a green oxidant (hydrogen peroxide) and green solvent (ethanol). Efficient epoxidation of indene and selective oxidation of 3,5-dimethylphenol and naphthalene to the corresponding quinones is observed.

  17. Synthesis, optical and electrochemical properties of Zn-porphyrin for dye sensitized solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Kotteswaran, S.; Pandian, M. Senthil; Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [SSN Research Centre, SSN College of Engineering, Chennai-603110, Tamilnadu (India)

    2016-05-23

    Zn-Porphyrin dye has been synthesized by the reaction between aldehydes and pyrrole. The dye structure was confirmed by {sup 1}H NMR, {sup 13}C NMR spectrum. The functional group of the dye molecule was confirmed by FTIR spectrum. The UV-Vis-NIR absorption spectrum of Zn-Porphyrin in DMF solution was recorded in spectrophotometer. The UV-Vis NIR spectrum of dye exhibits a strong Soret band and Q-band. Cyclic Voltammograms were obtained with three electrode systems: Pt as counter electrode, saturated calomel used as a reference electrode and glassy carbon as working electrode at a scan rate of 100 mV/s. The curves recorded the oxidation of 0.5 mM compound Zn-Porphyrin in a dichloromethane solution containing 0.1M TBAP as supporting electrolyte, reveal two successive quasi reversible redox couples with the first anodic and cathodic peak potentials of -0.2 V and -1 V. The second anodic and cathodic peak potentials are 0.82 V and 0.01 V respectively.

  18. XAFS Debye-Waller Factors Temperature-Dependent Expressions for Fe+2-Porphyrin Complexes

    International Nuclear Information System (INIS)

    Dimakis, Nicholas; Bunker, Grant

    2007-01-01

    We present an efficient and accurate method for directly calculating single and multiple scattering X-ray absorption fine structure (XAFS) thermal Debye-Waller factors for Fe+2 -porphiryn complexes. The number of multiple scattering Debye-Waller factors on metal porphyrin centers exceeds the number of available parameters that XAFS experimental data can support during fitting with simulated spectra. Using the Density Functional Theory (DFT) under the hybrid functional of X3LYP, phonon normal mode spectrum properties are used to express the mean square variation of the half-scattering path length for a Fe+2 -porphiryn complex as a function of temperature for the most important single and multiple scattering paths of the complex thus virtually eliminating them from the fitting procedure. Modeled calculations are compared with corresponding values obtained from DFT-built and optimized Fe+2 -porphyrin bis-histidine structure as well as from experimental XAFS spectra previously reported. An excellent agreement between calculated and reference Debye-Waller factors for Fe+2-porphyrins is obtained

  19. MS2 bacteriophage as a delivery vessel of porphyrins for photodynamic therapy

    Science.gov (United States)

    Cohen, Brian A.; Kaloyeros, Alain E.; Bergkvist, Magnus

    2011-02-01

    Challenges associated with photodynamic therapy (PDT) include the packaging and site-specific delivery of therapeutic agents to the tissue of interest. Nanoscale encapsulation of PDT agents inside targeted virus capsids is a novel concept for packaging and site-specific targeting. The icosahedral MS2 bacteriophage is one potential candidate for such a packaging-system. MS2 has a porous capsid with an exterior diameter of ~28 nm where the pores allow small molecules access to the capsid interior. Furthermore, MS2 presents suitable residues on the exterior capsid for conjugation of targeting ligands. Initial work by the present investigators has successfully demonstrated RNA-based self-packaging of a heterocyclic PDT agent (meso-tetrakis(para-N-trimethylanilinium)porphine, TMAP) into the MS2 capsid. Packaging photoactive compounds in confined spaces could result in energy transfer between the molecules upon photoactivation, which could in turn reduce the production of radical oxygen species (ROS). ROS are key components in photodynamic therapy, and a reduced production could negatively impact the efficacy of PDT treatment. Here, findings are presented from an investigation of ROS generation of TMAP encapsulated within the MS2 capsid compared to free TMAP in solution. Monitoring of ROS production upon photoactivation via a specific singlet oxygen assay revealed the impact on ROS generation between packaged porphyrins as compared to free porphyrin in an aqueous solution. Follow on work will study the ability of MS2-packaged porphyrins to generate ROS in vitro and subsequent cytotoxic effects on cells in culture.

  20. Trace Oxygen Sensitive Material Based on Two Porphyrin Derivatives in a Heterodimeric Complex

    Directory of Open Access Journals (Sweden)

    Eugenia Fagadar-Cosma

    2017-10-01

    Full Text Available The successful preparation of a novel dimer complex formed between 5,10,15,20-tetrakis(3,4-dimethoxyphenyl-porphyrin Fe(III chloride and (5,10,15,20-tetraphenylporphinato dichlorophosphorus(V chloride using the well-known reactivity of the P–X bond is reported. The obtained complex was characterized by UV-vis, Fourier transform infrared spectroscopy (FT-IR, fluorescence, 1H-NMR, 13C-NMR, and 31P-NMR spectroscopic techniques and also by additional Heteronuclear Single Quantum Coherence (HSQC and Heteronuclear Multiple Bond Correlation (HMBC experiments in order to correctly assign the NMR signals. Scanning electron microscopy (SEM and EDX quantifications completed the characterizations. This novel porphyrin dimer complex demonstrated fluorescence sensing of H2O2 in water for low oxygen concentrations in the range of 40–90 µM proving medical relevance for early diagnosis of diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and even cancer because higher concentrations of H2O2 than 50 μM are consideredcytotoxic for life. Due to its optical properties, this novel metalloporphyrin–porphyrin based complex is expected to show PDT and bactericidal activity under visible-light irradiation.

  1. The study of cellulosic fabrics impregnated with porphyrin compounds for use as photo-bactericidal polymers

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Rahmatollah, E-mail: rahimi_rah@iust.ac.ir [Bioinorganic Chemistry Laboratory, Department of Chemistry, Iran University of Science and Technology, Tehran 16846-13114 (Iran, Islamic Republic of); Fayyaz, Fatemeh [Bioinorganic Chemistry Laboratory, Department of Chemistry, Iran University of Science and Technology, Tehran 16846-13114 (Iran, Islamic Republic of); Rassa, Mehdi [Department of Biology, Faculty of Science, University of Guilan, Rasht (Iran, Islamic Republic of)

    2016-02-01

    In the present work, we report on the preparation of cellulosic fabrics bearing two types of photo-sensitizers in order to prepare efficient polymeric materials for antimicrobial applications. The obtained porphyrin-grafted cellulosic fabrics were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, diffuse reflectance UV–Vis (DRUV) spectroscopy, thermo-gravimetric analysis (TG) and scanning electron microscopy (SEM). Antimicrobial activity of the prepared porphyrin-cellulose was tested under visible light irradiation against Staphylococcus aureus, Pseudomunas aeroginosa and Escherichia coli. In addition, the effect of two parameters on photo-bactericidal activity of treated fibers was studied: illumination time and concentration of photosensitizers (PS). - Highlights: • Cellulosic fabrics were impregnated with various concentrations of porphyrins (TAPP and its zinc ion complex). • The products were characterized by ATR-FTIR, DRUV, SEM and TG. • The photo-antibacterial activity of products was determined against S. aureus, P. aeroginosa and E. coli. • The effect of two parameters were studied on photoinactivation of treated fibers: illumination time and concentration of PS.

  2. Studies of alkyl porphyrin distributions in organic-rich sediments using LC-MS

    International Nuclear Information System (INIS)

    Eckardt, C.B.; Carter, J.F.; Keely, B.J.; Maxwell, J.R.; Kilpatrick, G.

    1992-01-01

    In recent years, structure elucidation of a wide variety of sedimentary tetrapyrroles has provided clear molecular evidence for the presence of primary photosynthetic communities in palaeo water columns. The reported structures indicate an origin from algal chlorophylls c for certain components, while an origin from photosynthetic bacteria is apparent from the carbon skeletons of other components. In particular, the structures of ≤C 34 porphyrin carboxylic acids in the Eocene Messel shale indicate an origin from Chloroblum bacteria. Since such bacteria are strict anaerobes, the presence of these species is evidence for anoxic conditions extending into the photic zone of Messel lake. By analogy, the presence in the more widely-occurring alkyl porphyrin distributions of components >C 33 would also suggest a Chlorobium chlorophyll origin. Hence, in this paper, the authors studied by LC-MS, the distributions of alkyl porphyrins in selected sediments and searched for the presence of such components, in order to determine photic zone anoxia in the respective palaeo environments

  3. HepG2 human hepatocarcinomas cells sensitization by endogenous porphyrins

    Science.gov (United States)

    Vonarx-Coinsmann, Veronique; Foultier, Marie-Therese; de Brito, Leonor X.; Morlet, Laurent; Patrice, Thierry

    1995-03-01

    We assessed the ability of the human hepatocarcinoma cell line HepG2 to synthesize PpIX in vitro from exogenous ALA and analyzed ALA-induced toxicity and phototoxicity on this cell line. ALA induced a slight dose-dependent dark toxicity, with 79 and 66% cell survival respectively for ALA 50 and 100 mg/ml after 3-h incubation. Whereas the same treatment followed by laser irradiation (l equals 632 nm, 25 J/sq cm) induced dose-dependent phototoxicity, with 54 and 19% cell survival 24 h after PDT. Whatever the incubation time with ALA, a 3-h delay before light exposure was found optimal to reach a maximal phototoxicity. Photoproducts induced by porphyrin light irradiation absorbed light in the red spectral region at longer wavelengths than did the original porphyrins. The possible enhancement of PDT effects after ALA HepG2 cell incubation was investigated by irradiating cells successively with red light (l equals 632 nm) and light (l equals 650 nm). Total fluence was kept constant at 25 J/sq cm. Phototoxicity was lower when cells were irradiated for increased periods of l equals 650 nm light than with l equals 632 nm light alone. Any photoproducts involved had either a short life or were poorly photoreactive. HepG2 cells, synthesizing enzymes and precursors of endogenous porphyrin synthesis, represent a good in vitro model for experiments using ALA-PpIX-PDT.

  4. Porphyrin-containing polyaspartamide gadolinium complexes as potential magnetic resonance imaging contrast agents.

    Science.gov (United States)

    Yan, Guo-Ping; Li, Zhen; Xu, Wei; Zhou, Cheng-Kai; Yang, Lian; Zhang, Qiao; Li, Liang; Liu, Fan; Han, Lin; Ge, Yuan-Xing; Guo, Jun-Fang

    2011-04-04

    Porphyrin-containing polyaspartamide ligands (APTSPP-PHEA-DTPA) were synthesized by the incorporation of diethylenetriaminepentaacetic acid (DTPA) and 5-(4'-aminophenyl)-10,15,20-tris(4'-sulfonatophenyl) porphyrin, trisodium salt (APTSPP) into poly-α,β-[N-(2-hydroxyethyl)-l-aspartamide] (PHEA). These ligands were further reacted with gadolinium chloride to produce macromolecule-gadolinium complexes (APTSPP-PHEA-DTPA-Gd). Experimental data of (1)H NMR, IR, UV and elemental analysis evidenced the formation of the polyaspartamide ligands and gadolinium complexes. In vitro and in vivo property tests indicated that APTSPP-PHEA-DTPA-Gd possessed noticeably higher relaxation effectiveness, less toxicity to HeLa cells, and significantly higher enhanced signal intensities (SI) of the VX2 carcinoma in rabbits with lower injection dose requirement than that of Gd-DTPA. Moreover, APTSPP-PHEA-DTPA-Gd was found to greatly enhance the contrast of MR images of the VX2 carcinoma, providing prolonged intravascular duration, and distinguished the VX2 carcinoma and normal tissues in rabbits according to MR image signal enhancements. These porphyrin-containing polyaspartamide gadolinium complexes can be used as the candidates of contrast agents for targeted MRI to tumors. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  5. 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).

  6. 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).

  7. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

    Directory of Open Access Journals (Sweden)

    Ambrish Singh

    2015-08-01

    Full Text Available The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl-21H,23H-porphyrin (HPTB, 5,10,15,20-tetra(4-pyridyl-21H,23H-porphyrin (T4PP, 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayltetrakis(benzoic acid (THP and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP was studied using electrochemical impedance spectroscopy (EIS, potentiodynamic polarization, scanning electrochemical microscopy (SECM and scanning electron microscopy (SEM techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  8. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  9. Experimental study on the fragmentation of Adenine and Porphyrin molecules induced by low energy multicharged ion impact

    International Nuclear Information System (INIS)

    Li, B.

    2010-01-01

    Since the dissociation of small molecules might play key roles in the understanding of radiation induced damages of living tissues at the primary steps and at the molecular levels, fragmentation dynamics of small biomolecules have drawn much attention. The knowledge of the internal energy is of fundamental importance for understanding its fragmentation dynamics following external excitation. For a long time however, it was difficult to measure this parameter in coincidence with the fragmentation patterns until the development of CIDEC (Collision Induced Dissociation under Energy Control) method in 2007. In this work, the CIDEC method was extended to study the fragmentation of gas-phase biomolecules adenine (Ade: H 5 C 5 N 5 ) and porphyrin chloride FeTPPCl (C 44 H 28 N 4 FeCl). The population distribution for each dissociation channel as a function of the excitation energy of the parent molecular ions at a well-determined initial charge state has been experimentally determined, which could shed some light on the fragmentation dynamics of these molecules. In collisions between Cl + and Ade at 3 keV, the fragmentation pattern of Ade 2+ is dominated by the loss of H 2 CN + and the successive emission of HCN. The energy distribution of the parent dication confirms the successive emission dynamics. A specific decay channel is observed, i.e. the emission of a charged H 2 CN + followed by the emission of HC 2 N 2 . The measured mean excitation energies of this channel and other competitive channels are compared. In Kr 8+ - FeTPPCl collisions at 80 keV, parent ions FeTPPCL 1+,2+,3+ are observed, along with the corresponding decay patterns. It is found that, in the first step the dominant low-energy-cost decay channel is the emission of Cl 0 independent of the initial charge state of FeTPPCl r+ . For the resulted dication FeTPP 2+ , the dominant fragmentation channel is the neutral evaporation; for the tri-cation however, the dominant fragmentation channel is the

  10. Cation transport in isomeric pentanes

    International Nuclear Information System (INIS)

    Gyoergy, Istvan; Gee, Norman; Freeman, G.R.

    1985-01-01

    The cation mobility μsub(+) is measured in n-pentane, isopentane, neo-pentane, and mixtures of n- and neo-pentane over conditions from the normal liquid, through the critical fluid, to the low density gas. Most of the liquid data correlate with the reduced temperature T/Tsub(c). The T/Tsub(c) reflects free volume and viscosity changes. Comparison is made to neutral molecule diffusion. The transition from viscosity control of mobility in the liquid to density control in the dilute gas occurs over the reduced viscosity region 3 > eta/etasub(c) > 0.6, which corresponds to the reduced density region 1.9 > eta/etasub(c) > 0.5. In the saturated gas etaμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average gas nμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average momentum transfer cross sections in the n-/neo-pentane mixtures are similar to those in neo-pentane at low T but similar to those in n-pentane at high T. The present findings are combined with previous electron mobility data in addressing the effect of hydrocarbon molecular (external) shape on the electric breakdown strength of gases

  11. Cationic Bolaamphiphiles for Gene Delivery

    Science.gov (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  12. Stressor states and the cation crossroads.

    Science.gov (United States)

    Weber, Karl T; Bhattacharya, Syamal K; Newman, Kevin P; Soberman, Judith E; Ramanathan, Kodangudi B; McGee, Jesse E; Malik, Kafait U; Hickerson, William L

    2010-12-01

    Neurohormonal activation involving the hypothalamic-pituitary-adrenal axis and adrenergic nervous and renin-angiotensin-aldosterone systems is integral to stressor state-mediated homeostatic responses. The levels of effector hormones, depending upon the degree of stress, orchestrate the concordant appearance of hypokalemia, ionized hypocalcemia and hypomagnesemia, hypozincemia, and hyposelenemia. Seemingly contradictory to homeostatic responses wherein the constancy of extracellular fluid would be preserved, upregulation of cognate-binding proteins promotes coordinated translocation of cations to injured tissues, where they participate in wound healing. Associated catecholamine-mediated intracellular cation shifts regulate the equilibrium between pro-oxidants and antioxidant defenses, a critical determinant of cell survival. These acute and chronic stressor-induced iterations in extracellular and intracellular cations are collectively referred to as the cation crossroads. Intracellular cation shifts, particularly excessive accumulation of Ca2+, converge on mitochondria to induce oxidative stress and raise the opening potential of their inner membrane permeability transition pores (mPTPs). The ensuing loss of cationic homeostasis and adenosine triphosphate (ATP) production, together with osmotic swelling, leads to organellar degeneration and cellular necrosis. The overall impact of iterations in extracellular and intracellular cations and their influence on cardiac redox state, cardiomyocyte survival, and myocardial structure and function are addressed herein.

  13. A novel chlorine derivative of Meso-tris(pentafluorophenyl)-4-pyridyl porphyrin: synthesis, photophysics and photochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Maestrin, Ana Paula J.; Ribeiro, Anderson O.; Tedesco, Antonio Claudio; Neri, Claudio R.; Vinhado, Fabio S.; Serra, Osvaldo A.; Martins, Patricia R.; Iamamoto, Yassuko [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Inst. de Quimica]. E-mail: oaserra@ffclrp.usp.br; Silva, Ana Margarida G.; Tome, Augusto C.; Neves, Maria G.P.M.S.; Cavaleiro, Jose A.S. [Universidade de Aveiro (Portugal). Dept. de Quimica]. E-mail: jcavaleiro@dq.ua.pt

    2004-12-01

    Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorine, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorine-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorine derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, {sup 1}H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorine 4 have been evaluated. Its quantum yield of photobleaching ({phi}{sub Pb}, mol Einstein{sup -1}) was 0.047{+-}0.014. In order to demonstrate the production of {sup 1}O{sub 2} when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorine 4 can be considered a promising photosensitizer in PDT. (author)

  14. A novel chlorine derivative of Meso-tris(pentafluorophenyl)-4-pyridyl porphyrin: synthesis, photophysics and photochemical properties

    International Nuclear Information System (INIS)

    Maestrin, Ana Paula J.; Ribeiro, Anderson O.; Tedesco, Antonio Claudio; Neri, Claudio R.; Vinhado, Fabio S.; Serra, Osvaldo A.; Martins, Patricia R.; Iamamoto, Yassuko; Silva, Ana Margarida G.; Tome, Augusto C.; Neves, Maria G.P.M.S.; Cavaleiro, Jose A.S.

    2004-01-01

    Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorine, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorine-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorine derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H- N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, 1 H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorine 4 have been evaluated. Its quantum yield of photobleaching (φ Pb , mol Einstein -1 ) was 0.047±0.014. In order to demonstrate the production of 1 O 2 when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorine 4 can be considered a promising photosensitizer in PDT. (author)

  15. Covalent functionalization of reduced graphene oxide with porphyrin by means of diazonium chemistry for nonlinear optical performance

    Science.gov (United States)

    Wang, Aijian; Yu, Wang; Huang, Zhipeng; Zhou, Feng; Song, Jingbao; Song, Yinglin; Long, Lingliang; Cifuentes, Marie P.; Humphrey, Mark G.; Zhang, Long; Shao, Jianda; Zhang, Chi

    2016-03-01

    Reduced graphene oxide (RGO)-porphyrin (TPP) nanohybrids (RGO-TPP 1 and RGO-TPP 2) were prepared by two synthetic routes that involve functionalization of the RGO using diazonium salts. The microscopic structures, morphology, photophysical properties and nonlinear optical performance of the resultant RGO-TPP nanohybrids were investigated. The covalent bonding of the porphyrin-functionalized-RGO nanohybrid materials was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Attachment of the porphyrin units to the surface of the RGO by diazotization significantly improves the solubility and ease of processing of these RGO-based nanohybrid materials. Ultraviolet/visible absorption and steady-state fluorescence studies indicate considerable π-π interactions and effective photo-induced electron and/or energy transfer between the porphyrin moieties and the extended π-system of RGO. The nonlinear optical properties of RGO-TPP 1 and RGO-TPP 2 were investigated by open-aperture Z-scan measurements at 532 nm with both 4 ns and 21 ps laser pulses, the results showing that the chemical nanohybrids exhibit improved nonlinear optical properties compared to those of the benchmark material C60, and the constituent RGO or porphyrins.

  16. Shedding lights on the flexible-armed porphyrins: Human telomeric G4 DNA interaction and cell photocytotoxicity research.

    Science.gov (United States)

    Sun, Xiang-Yu; Zhao, Ping; Jin, Shu-Fang; Liu, Min-Chao; Wang, Xia-Hong; Huang, Yu-Min; Cheng, Zhen-Feng; Yan, Si-Qi; Li, Yan-Yu; Chen, Ya-Qing; Zhong, Yan-Mei

    2017-08-01

    DNA polymorphism exerts a fascination on a large scientific community. Without crystallographic structural data, clarification of the binding modes between G-quadruplex (G4) and ligand (complex) is a challenging job. In the present work, three porphyrin compounds with different flexible carbon chains (arms) were designed, synthesized and characterized. Their binding, folding and stabilizing abilities to human telomeric G4 DNA structures were comparatively researched. Positive charges at the end of the flexible carbon chains seem to be favorable for the DNA-porphyrin interactions, which were evidenced by the spectral results and further confirmed by the molecular docking calculations. Biological function analysis demonstrated that these porphyrins show no substantial inhibition to Hela, A549 and BEL 7402 cancer cell lines under dark while exhibit broad inhibition under visible light. This significantly enhanced photocytotoxicity relative to the dark control is an essential property of photochemotherapeutic agents. The feature of the flexible arms emerges as critical influencing factors in the cell photocytotoxicity. Moreover, an ROS-mediated mitochondrial dysfunction pathway was suggested for the cell apoptosis induced by these flexible-armed porphyrins. It is found that the porphyrins with positive charges located at the end of the flexible arms represent an exciting opportunity for photochemotherapeutic anti-cancer drug design. Copyright © 2017. Published by Elsevier B.V.

  17. 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

  18. A novel self-assembly with zinc porphyrin coordination polymer for enhanced photocurrent conversion in supramolecular solar cells

    International Nuclear Information System (INIS)

    Cao, Jing; Liu, Jia-Cheng; Deng, Wen-Ting; Li, Ren-Zhi; Jin, Neng-Zhi

    2013-01-01

    Graphical abstract: An innovative type of self-assembly based on acetohydrazide zinc porphyrin coordination polymer has been prepared in supramolecular solar cells. - Highlights: • A novel assembly with acetohydrazide porphyrin coordination polymer. • The assembly based on porphyrin is prepared as parallel sample. • Coordination polymer-based assembly shows enhanced photoelectronic behavior. • A series of different organic acid ligands as anchoring groups are prepared. - Abstract: In this work, a novel acetohydrazide zinc porphyrin-based coordination polymer (CP)-isonicotinic acid self-assembly by metal-ligand axial coordination to modify the nano-structured TiO 2 electrode surface has been investigated in photoelectrochemical device. Compared to the assembly based on corresponding zinc porphyrin combined with isonicotinic acid by metal-ligand axial coordination, CP-isonicotinic acid assembly exhibits a significantly enhanced photoelectronic behavior. In addition, a series of different organic acid ligands were prepared to probe the impact of their structures on the photoelectronic performances of their corresponding assemblies-sensitized cells. This study affords a novel type of self-assembly to functionalize the nanostructured TiO 2 electrode surface in supramolecular solar cells

  19. Probing the Compound I-like reactivity of a bare high-valent oxo iron porphyrin complex: the oxidation of tertiary amines.

    Science.gov (United States)

    Chiavarino, Barbara; Cipollini, Romano; Crestoni, Maria Elisa; Fornarini, Simonetta; Lanucara, Francesco; Lapi, Andrea

    2008-03-12

    The mechanisms of oxidative N-dealkylation of amines by heme enzymes including peroxidases and cytochromes P450 and by functional models for the active Compound I species have long been studied. A debated issue has concerned in particular the character of the primary step initiating the oxidation sequence, either a hydrogen atom transfer (HAT) or an electron transfer (ET) event, facing problems such as the possible contribution of multiple oxidants and complex environmental effects. In the present study, an oxo iron(IV) porphyrin radical cation intermediate 1, [(TPFPP)*+ Fe(IV)=O]+ (TPFPP = meso-tetrakis (pentafluorophenyl)porphinato dianion), functional model of Compound I, has been produced as a bare species. The gas-phase reaction with amines (A) studied by ESI-FT-ICR mass spectrometry has revealed for the first time the elementary steps and the ionic intermediates involved in the oxidative activation. Ionic products are formed involving ET (A*+, the amine radical cation), formal hydride transfer (HT) from the amine ([A(-H)]+, an iminium ion), and oxygen atom transfer (OAT) to the amine (A(O), likely a carbinolamine product), whereas an ionic product involving a net initial HAT event is never observed. The reaction appears to be initiated by an ET event for the majority of the tested amines which included tertiary aliphatic and aromatic amines as well as a cyclic and a secondary amine. For a series of N,N-dimethylanilines the reaction efficiency for the ET activated pathways was found to correlate with the ionization energy of the amine. A stepwise pathway accounts for the C-H bond activation resulting in the formal HT product, namely a primary ET process forming A*+, which is deprotonated at the alpha-C-H bond forming an N-methyl-N-arylaminomethyl radical, A(-H)*, readily oxidized to the iminium ion, [A(-H)]+. The kinetic isotope effect (KIE) for proton transfer (PT) increases as the acidity of the amine radical cation increases and the PT reaction to the base

  20. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  1. Radioimmunoassay of human eosinophil cationic protein

    International Nuclear Information System (INIS)

    Venge, P.; Roxin, L.E.; Olsson, I.

    1977-01-01

    A radioimmunosorbent assay has been developed which allows the detection in serum of a cationic protein derived from eosinophil granulocytes. In 34 healthy individuals the mean level was 31 μg/l. with a range of 5 to 55 μg/l. The serum concentration of 'eosinophil' cationic protein was correlated (P<0.001) to the number of eosinophil granulocytes in peripheral blood. Quantitiation of 'eosinophil' cationic protein in serum might be useful in the study of eosinophil granulocyte turnover and function in vivo. (author)

  2. TMPyP4 porphyrin distorts RNA G-quadruplex structures of the disease-associated r(GGGGCC)n repeat of the C9orf72 gene and blocks interaction of RNA-binding proteins.

    Science.gov (United States)

    Zamiri, Bita; Reddy, Kaalak; Macgregor, Robert B; Pearson, Christopher E

    2014-02-21

    Certain DNA and RNA sequences can form G-quadruplexes, which can affect genetic instability, promoter activity, RNA splicing, RNA stability, and neurite mRNA localization. Amyotrophic lateral sclerosis and frontotemporal dementia can be caused by expansion of a (GGGGCC)n repeat in the C9orf72 gene. Mutant r(GGGGCC)n- and r(GGCCCC)n-containing transcripts aggregate in nuclear foci, possibly sequestering repeat-binding proteins such as ASF/SF2 and hnRNPA1, suggesting a toxic RNA pathogenesis, as occurs in myotonic dystrophy. Furthermore, the C9orf72 repeat RNA was recently demonstrated to undergo the noncanonical repeat-associated non-AUG translation (RAN translation) into pathologic dipeptide repeats in patient brains, a process that is thought to depend upon RNA structure. We previously demonstrated that the r(GGGGCC)n RNA forms repeat tract length-dependent G-quadruplex structures that bind the ASF/SF2 protein. Here we show that the cationic porphyrin (5,10,15,20-tetra(N-methyl-4-pyridyl) porphyrin (TMPyP4)), which can bind some G-quadruplex-forming sequences, can bind and distort the G-quadruplex formed by r(GGGGCC)8, and this ablates the interaction of either hnRNPA1 or ASF/SF2 with the repeat. These findings provide proof of concept that nucleic acid binding small molecules, such as TMPyP4, can distort the secondary structure of the C9orf72 repeat, which may beneficially disrupt protein interactions, which may ablate either protein sequestration and/or RAN translation into potentially toxic dipeptides. Disruption of secondary structure formation of the C9orf72 RNA repeats may be a viable therapeutic avenue, as well as a means to test the role of RNA structure upon RAN translation.

  3. Cationization of heparin for film applications

    Czech Academy of Sciences Publication Activity Database

    Šimkovic, I.; Mendichi, R.; Kelnar, Ivan; Filip, J.; Hricovíni, M.

    2015-01-01

    Roč. 115, 22 January (2015), s. 551-558 ISSN 0144-8617 Institutional support: RVO:61389013 Keywords : heparin * cationization * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.219, year: 2015

  4. Mn porphyrin-based SOD mimic, MnTnHex-2-PyP(5+), and non-SOD mimic, MnTBAP(3-), suppressed rat spinal cord ischemia/reperfusion injury via NF-κB pathways.

    Science.gov (United States)

    Celic, T; Španjol, J; Bobinac, M; Tovmasyan, A; Vukelic, I; Reboucas, J S; Batinic-Haberle, I; Bobinac, D

    2014-12-01

    Herein we have demonstrated that both superoxide dismutase (SOD) mimic, cationic Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP(5+)), and non-SOD mimic, anionic Mn(III) meso-tetrakis(4-carboxylatophenyl)porphyrin (MnTBAP(3-)), protect against oxidative stress caused by spinal cord ischemia/reperfusion via suppression of nuclear factor kappa B (NF-κB) pro-inflammatory pathways. Earlier reports showed that Mn(III) N-alkylpyridylporphyrins were able to prevent the DNA binding of NF-κB in an aqueous system, whereas MnTBAP(3-) was not. Here, for the first time, in a complex in vivo system-animal model of spinal cord injury-a similar impact of MnTBAP(3-), at a dose identical to that of MnTnHex-2-PyP(5+), was demonstrated in NF-κB downregulation. Rats were treated subcutaneously at 1.5 mg/kg starting at 30 min before ischemia/reperfusion, and then every 12 h afterward for either 48 h or 7 days. The anti-inflammatory effects of both Mn porphyrins (MnPs) were demonstrated in the spinal cord tissue at both 48 h and 7 days. The downregulation of NF-κB, a major pro-inflammatory signaling protein regulating astrocyte activation, was detected and found to correlate well with the suppression of astrogliosis (as glial fibrillary acidic protein) by both MnPs. The markers of oxidative stress, lipid peroxidation and protein carbonyl formation, were significantly reduced by MnPs. The favorable impact of both MnPs on motor neurons (Tarlov score and inclined plane test) was assessed. No major changes in glutathione peroxidase- and SOD-like activities were demonstrated, which implies that none of the MnPs acted as SOD mimic. Increasing amount of data on the reactivity of MnTBAP(3-) with reactive nitrogen species (RNS) (.NO/HNO/ONOO(-)) suggests that RNS/MnTBAP(3-)-driven modification of NF-κB protein cysteines may be involved in its therapeutic effects. This differs from the therapeutic efficacy of MnTnHex-2-PyP(5+) which presumably occurs via reactive

  5. First Example of a Lipophilic Porphyrin-Cardanol Hybrid Embedded in a Cardanol-Based Micellar Nanodispersion

    Directory of Open Access Journals (Sweden)

    Giuseppe Vasapollo

    2012-10-01

    Full Text Available Cardanol is a natural and renewable organic raw material obtained as the major chemical component by vacuum distillation of cashew nut shell liquid. In this work a new sustainable procedure for producing cardanol-based micellar nanodispersions having an embedded lipophilic porphyrin itself peripherally functionalized with cardanol substituents (porphyrin-cardanol hybrid has been described for the first time. In particular, cardanol acts as the solvent of the cardanol hybrid porphyrin and cholesterol as well as being the main component of the nanodispersions. In this way a “green” micellar nanodispersion, in which a high percentage of the micellar system is derived from renewable “functional” molecules, has been produced.

  6. Efficient solar cells sensitized by porphyrins with an extended conjugation framework and a carbazole donor: from molecular design to cosensitization.

    Science.gov (United States)

    Wang, Yueqiang; Chen, Bin; Wu, Wenjun; Li, Xin; Zhu, Weihong; Tian, He; Xie, Yongshu

    2014-09-26

    Porphyrin dyes containing the carbazole electron donor have been designed and optimized by wrapping the porphyrin framework, introducing an additional ethynylene bridge to extend the wavelength range of light absorption, and further suppression of the dye aggregation by introducing additional alkoxy chains. Application of a cosensitization approach results in improved current density (Jsc) and open-circuit voltage (Voc) values, thus achieving the highest cell efficiency of 10.45%. This work provides an effective combined strategy of molecular design and cosensitization for developing efficient dye-sensitized solar cells (DSSCs). In addition, carbazole has been demonstrated to be a promising donor for porphyrin sensitizers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Water-soluble Manganese and Iron Mesotetrakis(carboxyl)porphyrin: DNA Binding, Oxidative Cleavage, and Cytotoxic Activities.

    Science.gov (United States)

    Shi, Lei; Jiang, Yi-Yu; Jiang, Tao; Yin, Wei; Yang, Jian-Ping; Cao, Man-Li; Fang, Yu-Qi; Liu, Hai-Yang

    2017-06-29

    Two new water-soluble metal carboxyl porphyrins, manganese (III) meso -tetrakis (carboxyl) porphyrin and iron (III) meso -tetrakis (carboxyl) porphyrin, were synthesized and characterized. Their interactions with ct-DNA were investigated by UV-Vis titration, fluorescence spectra, viscosity measurement and CD spectra. The results showed they can strongly bind to ct-DNA via outside binding mode. Electrophoresis experiments revealed that both complexes can cleave pBR322 DNA efficiently in the presence of hydrogen peroxide, albeit 2-Mn exhibited a little higher efficiency. The inhibitor tests suggest the oxidative DNA cleavage by these two complexes may involve hydroxyl radical active intermediates. Notably, 2-Mn exhibited considerable photocytotoxicity against Hep G2 cell via triggering a significant generation of ROS and causing disruption of MMP after irradiation.

  8. Perturbations in DNA structure upon interaction with porphyrins revealed by chemical probes, DNA footprinting and molecular modelling.

    Science.gov (United States)

    Ford, K G; Neidle, S

    1995-06-01

    The interactions of several porphyrins with a 74 base-pair DNA sequence have been examined by footprinting and chemical protection methods. Tetra-(4-N-methyl-(pyridyl)) porphyrin (TMPy), two of its metal complexes and tetra-(4-trimethylanilinium) porphyrin (TMAP) bind to closely similar AT-rich sequences. The three TMPy ligands produce modest changes in DNA structure and base accessibility on binding, in contrast to the large-scale conformational changes observed with TMAP. Molecular modelling studies have been performed on TMPy and TMAP bound in the AT-rich minor groove of an oligonucleotide. These have shown that significant structural change is needed to accommodate the bulky trimethyl substituent groups of TMAP, in contrast to the facile minor groove fit of TMPy.

  9. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  10. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    Verschueren, K.; Balwant Kaur

    1999-01-01

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  11. Chemical reactivity of cation-exchanged zeolites

    OpenAIRE

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed by Brønsted acid sites in the hydrogen forms of zeolites, the nature of chemical reactivity, and related, the structure of the metal-containing ions in cation-exchanged zeolites remains the subject...

  12. Restructuring of a peat in interaction with multivalent cations: effect of cation type and aging time.

    Science.gov (United States)

    Kunhi Mouvenchery, Yamuna; Jaeger, Alexander; Aquino, Adelia J A; Tunega, Daniel; Diehl, Dörte; Bertmer, Marko; Schaumann, Gabriele Ellen

    2013-01-01

    It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM) molecules via cation bridges (CaB). The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al(3+), Ca(2+) or Na(+), respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>2 h) than deprotonation of functional groups (cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB) and molecular mobility of water (NMR analysis) suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat) cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is decisive for CaB and aging-induced structural reorganisation can enhance cross-link formation.

  13. Charge-transfer state and large first hyperpolarizability constant in a highly electronically coupled zinc and gold porphyrin dyad.

    Science.gov (United States)

    Fortage, Jérôme; Scarpaci, Annabelle; Viau, Lydie; Pellegrin, Yann; Blart, Errol; Falkenström, Magnus; Hammarström, Leif; Asselberghs, Inge; Kellens, Ruben; Libaers, Wim; Clays, Koen; Eng, Mattias P; Odobel, Fabrice

    2009-09-14

    We report the synthesis and the characterizations of a novel dyad composed of a zinc porphyrin (ZnP) linked to a gold porphyrin (AuP) through an ethynyl spacer. The UV/Vis absorption spectrum and the electrochemical properties clearly reveal that this dyad exhibits a strong electronic coupling in the ground state as evidenced by shifted redox potentials and the appearance of an intense charge-transfer band localized at lambda = 739 nm in dichloromethane. A spectroelectrochemical study of the dyad along with the parent homometallic system (i.e., ZnP-ZnP and AuP-AuP) was undertaken to determine the spectra of the reduced and oxidized porphyrin units. Femtosecond transient absorption spectroscopic analysis showed that the photoexcitation of the heterometallic dyad leads to an ultrafast formation of a charge-separated state ((+)ZnP-AuP(*)) that displays a particularly long lifetime (tau = 4 ns in toluene) for such a short separation distance. The molecular orbitals of the dyad were determined by DFT quantum-chemical calculations. This theoretical study confirms that the observed intense band at lambda = 739 nm corresponds to an interporphyrin charge-transfer transition from the HOMO orbital localized on the zinc porphyrin to LUMO orbitals localized on the gold porphyrin. Finally, a Hyper-Rayleigh scattering study shows that the dyad possesses a large first molecular hyperpolarizability coefficient (beta = 2100x10(-30) esu at lambda = 1064 nm), thus highlighting the valuable nonlinear optical properties of this new type of push-pull porphyrin system.

  14. "Spider"-shaped porphyrins with conjugated pyridyl anchoring groups as efficient sensitizers for dye-sensitized solar cells.

    Science.gov (United States)

    Stangel, Christina; Bagaki, Anthi; Angaridis, Panagiotis A; Charalambidis, Georgios; Sharma, Ganesh D; Coutsolelos, Athanasios G

    2014-11-17

    Two novel "spider-shaped" porphyrins, meso-tetraaryl-substituted 1PV-Por and zinc-metalated 1PV-Zn-Por, bearing four oligo(p-phenylenevinylene) (oPPV) pyridyl groups with long dodecyloxy chains on the phenyl groups, have been synthesized. The presence of four pyridyl groups in both porphyrins, which allow them to act as anchoring groups upon coordination to various Lewis acid sites, the conjugated oPPV bridges, which offer the possibility of electronic communication between the porphyrin core and the pyridyl groups, and the dodecyloxy groups, which offer the advantage of high solubility in a variety of organic solvents of different polarities and could prevent porphyrin aggregation, renders porphyrins 1PV-Por and 1PV-Zn-Por very promising sensitizers for dye-sensitized solar cells (DSSCs). Photophysical measurements, together with electrochemistry experiments and density functional theory calculations, suggest that both porphyrins have frontier molecular orbital energy levels that favor electron injection and dye regeneration in DSSCs. Solar cells sensitized by 1PV-Por and 1PV-Zn-Por were fabricated, and it was found that they show power conversion efficiencies (PCEs) of 3.28 and 5.12%, respectively. Photovoltaic measurements (J-V curves) together with incident photon-to-electron conversion efficiency spectra of the two cells reveal that the higher PCE value of the DSSC based on 1PV-Zn-Por is ascribed to higher short-circuit current (Jsc), open-circuit voltage (Voc), and dye loading values. Emission spectra and electrochemistry experiments suggest a greater driving force for injection of the photogenerated electrons into the TiO2 conduction band for 1PV-Zn-Por rather than its free-base analogue. Furthermore, electrochemical impedance spectroscopy measurements prove that the utilization of 1PV-Zn-Por as a sensitizer offers a high charge recombination resistance and, therefore, leads to a longer electron lifetime.

  15. Formation of radical cations of diaryloxadiazoles

    International Nuclear Information System (INIS)

    Helmstreit, W.

    1988-01-01

    The nature of the formation of the radical cation of the 2,5-bis-(p-diethylaminophenyl)-1,3,4-oxadiazole (PC) in liquid n-butyl chloride and acetonitrile has been investigated by observing excited state fluorescence and transient absorption using nanosecond pulse radiolysis and laser flash photolysis. The formation of solute oxonium ions has also been observed. At concentrations -4 mol dm -3 the growth time at which the transient absorption of the radical cation reaches the maximum follows the rise time of the electron pulse ( 2 laser yields the solute radical cation in an acetonitrile solution of 2 x 10 -4 mol dm -3 PC via an electronically excited state. Here, the generation time was smaller than 5 ns. The yield of the cation is increased by addition of CCl 4 . A reaction mechanism is proposed that explains the fast cation formation in terms of an exciplex formed by interaction between an electronically excited state of diaryloxadiazole and the ground state of the solvent. This exciplex yields the solute radical cation. (author)

  16. Luminescent sulfides of monovalent and trivalent cations

    International Nuclear Information System (INIS)

    1975-01-01

    The invention discloses a family of luminescent materials or phosphors having a rhombohedral crystal structure and consisting essentially of a mixed host sulfide of at least one monovalent host cation and at least one trivalent host cation, and containing, for each mole of phosphor, 0.0005 to 0.05 mole of at least one activating cation. The monovalent host cations may be Na, K or Rb and Cs. The trivalent host cations may be Gd, La, Lu, Sc and Y. The activating cations may be one or more of trivalent As, Bi, Ce, Dy, Er, Pr, Sb, Sm, Tb and Tm; divalent Lu, Mn, Pb and Sn; and monovalent Ag, Cu and Tl. The novel phosphors may be used in devices to convert electron-beam, ultraviolet or x-ray energy to light in the visible spectrum. Such energy conversion can be employed for example in fluoroscopic screens, and in viewing screens of cathode-ray tubes and other electron tubes

  17. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation.

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-28

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  18. Theoretical study of a neutral, doubly protonated, and doubly deprotonated porphyrin dithiolate used as a molecular switch

    International Nuclear Information System (INIS)

    Girard, Yvan; Kondo, Masakazu; Yoshizawa, Kazunari

    2006-01-01

    The zero-bias conductance of the neutral, doubly protonated, and doubly deprotonated porphyrin molecules used as molecular junctions between gold electrodes is investigated by using a Green's function formalism combined with density functional theory calculations. The probability for an electron to scatter through the porphyrin is predicted to be significantly increased by the protonation or the deprotonation, and the molecule could be used as a switch controlled by the pH. The shapes and energies of the frontier orbitals are used to rationalize these results

  19. Synthesis and characterization of a new porphyrin-polyoxometalate hybrid material and investigation of its catalytic activity.

    Science.gov (United States)

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

    2012-03-14

    In the present work, the preparation of a new organic-inorganic hybrid material in which tetrakis(p-aminophenylporphyrin) is covalently linked to a Lindqvist structure of polyoxometalate, is reported. This new porphyrin-polyoxometalate hybrid material was characterized by (1)H NMR, FT-IR and UV-Vis spectroscopic methods and cyclic voltammetry. These spectro- and electrochemical studies provided spectral data of the synthesis of this compound. Cyclic voltammetry showed the influence of the porphyrin on the redox process of the polyoxometalate. The catalytic activity of this hybrid material was investigated in the alkene epoxidation with NaIO(4).

  20. A Zinc Porphyrin Sensitizer Modified with Donor and Acceptor Groups for Dye-ensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, See Woo; Sarker, K. Ashis; Hong, Jong Dal [Incheon National University, Incheon (Korea, Republic of)

    2014-09-15

    In this article, we have designed and synthesized a novel donor-π-acceptor (D-π-A) type porphyrin-based sensitizer (denoted UI-5), in which a carboxyl anchoring group and a 9,9-dimethyl fluorene were introduced at the meso-positions of porphyrin ring via phenylethynyl and ethynyl bridging units, respectively. Long alkoxy chains in ortho-positions of the phenyls were supposed to reduce the degree of dye aggregation, which tends to affect electron injection yield in a photovoltaic cell. The cyclic voltammetry was employed to determine the band gap of UI-5 to be 1.41 eV based on the HOMO and LUMO energy levels, which were estimated by the onset oxidation and reduction potentials. The incident monochromatic photon-to-current conversion efficiency of the UI-5 DSSC assembled with double-layer (20 nm-sized TiO{sub 2}/400 nm-sized TiO{sub 2}) film electrodes appeared lower upon overall ranges of the excitation wavelengths, but exhibited a higher value over the NIR ranges (λ = 650-700 nm) compared to the common reference sensitizer N719. The UI-5-sensitized cell yielded a relatively poor device performance with an overall conversion efficiency of 0.74% with a short circuit photocurrent density of 3.05 mA/cm2, an open circuit voltage of 0.54 mV and a fill factor of 0.44 under the standard global air mass (AM 1.5) solar conditions. However, our report about the synthesis and the photovoltaic characteristics of a porphyrin-based sensitizer in a D-π-A structure demonstrated a significant complex relationship between the sensitizer structure and the cell performance.

  1. Molecular Structure and Electronic Properties of Porphyrin-Thiophene-Perylene Using Quantum Chemical Calculation

    Directory of Open Access Journals (Sweden)

    Tatiya Chokbunpiam

    2010-01-01

    Full Text Available This study aimed to design a new series of compounds consisting of a porphyrin macrocycle linked to a perylene unit via a thiophenic bridge. The structural and electronic properties of the molecules, and the effects of mono- and di-substituents R on C3 and R′ on C4 of the thiophene ring were investigated using a quantum calculation approach. The results from the method validation revealed that using the density functional theory approach at B3LYP/6–31G(d data set was the optimal one, considering the accuracy attained and maintaining the computer time required within tractable limits. The results from the B3LYP/6–31G(d approach indicated that significant changes of the torsion angle between the molecular planes of the porphyrin and perylene rings, compared to that of the unsubstituted derivatives, were found in the di-substituted systems bearing R = R′ = −OCH3 and −NH2, and in a mono-substituted system having R = −H and R′=−NH2. The symmetric di-substitution does not provide a significantly lower HOMO-LUMO energy gap (ΔEg. Noticeable decreases in ΔEg were found only with the substitution patterns of: R, R′ = −OCH3, −H; −OH, −H; −N(CH32, −H; −H, −NH2. UV-visible spectra of all derivatives exhibited characteristic absorption maxima of the free bases of porphyrin and perylene.

  2. Photoconductivity of nanowires that are self-assembled from chiral porphyrins

    Science.gov (United States)

    Menko, J. G.; Smith, W. F.; Lu, Y.; Johnson, A. T.; Iavicoli, P.

    2010-03-01

    Recently synthesized chiral porphyrin moleculesfootnotetextM. Linares, P. Iavicoli, K. Psychogyiopoulou, D. Beljonne, S. De Feyter, D. B. Amabilino, and R. Lazzaroni, Langmuir 2008, 24, 9566-9574. in a methlocyclohexane solvent self-assemble into aggregates which appear as a network of nanoscale filaments when deposited onto oxidized silicon. We have shown in preliminary experiments conducted in air that the aggregates are photoconductive, with an action spectrum (photoconductivity vs. wavelength) that matches the in-solution absorbance curve. We discuss these results, and also experiments conducted in a dry nitrogen environment.

  3. Optimizing porphyrins for dye sensitized solar cells using large-scale ab initio calculations

    DEFF Research Database (Denmark)

    Ørnsø, Kristian Baruël; Pedersen, Christian S.; García Lastra, Juan Maria

    2014-01-01

    different side and anchoring groups. Based on the calculated frontier orbital energies and optical gaps we quantify the energy level alignment with the TiO2 conduction band and different redox mediators. An analysis of the energy level-structure relationship reveals a significant structural diversity among...... the dyes with the highest level alignment quality, demonstrating the large degree of flexibility in porphyrin dye design. As a specific example of dye optimization, we show that the level alignment of the high efficiency record dye YD2-o-C8 [Yella et al., Science, 2011, 334, 629-634] can be significantly...

  4. Development of radiolanthanide labeled porphyrin complexes as possible therapeutic agents in beast carcinoma xenografts

    Energy Technology Data Exchange (ETDEWEB)

    Vahidfar, Nasim; Aghanejad, Ayuob; Beiki, Davood; Khalaj, Ali [Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of). Faculty of Pharmacy; Jalilian, Amir R.; Fazaeli, Yousef; Bahrami-Samani, Ali; Alirezapour, Behrooz; Erfani, Mostafa [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiopharmacy Research Group

    2014-10-01

    Radiolabeled porphyrins are potential tumor avid radiopharmaceuticals because of their behaviour in the human body, ability to complex various radionuclides, water solubility, low toxicity etc., in this work radio ytterbium/samarium porphyrin complexes have been developed. {sup 175}Yb and {sup 153}Sm labeled 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) porphyrins ([{sup 175}Yb]-TDMPP/[{sup 153}Sm]-TDMPP) were prepared using 5,10,15,20-tetrakis(3,4-dimethoxyphenyl) porphyrin (H{sub 2}TDMPP) and [{sup 175}Yb]YbCl{sub 3} or [{sup 153}Sm]SmCl{sub 3} in 12-24 h at 60 C. Stability of the complexes were checked in final formulation and human serum for 24 h, followed by partition coefficient determination and biodistribution studies in wild type and breast carcinoma-bearing mice. The radiocomplexes were obtained with acceptable radiochemical purity (> 95% (paper chromatography) and > 96% (HPLC) for [{sup 175}Yb]-TDMPP and > 97% (paper chromatography) and > 98% (HPLC) for [{sup 153}Sm]-TDMPP) with specific activities of 12-15 GBq/mmol and 278 GBq/mmol at the end of bombardment for [{sup 175}Yb]-TDMPP and [{sup 153}Sm]-TDMPP respectively. The partition coefficients were determined for [{sup 175}Yb]-TDMPP and [{sup 153}Sm]-TDMPP (log P = 0.63 and log P = 0.96 respectively). The [{sup 175}Yb]-TDMPP complex is mostly washed out from the circulation through kidneys. Liver and spleen also demonstrated significant activity uptake in 72 h post injection. Also [{sup 153}Sm]-TDMPP, is mostly washed out from the circulation through kidneys, however lungs are the major accumulation sites. The [{sup 153}Sm]-TDMPP complex demonstrated significant targeted uptake in breast carcinoma xenografts with tumor: blood ratios of 10.67, 10.47 and 19.01 in 24, 48 and 72 h respectively. Also interesting tumor: kidney/liver ratios were obtained. {sup 153}Sm-TDMPP properties suggest an efficient tumor targeting agent with high tumor-avidity. Further investigation on the therapeutic properties must be

  5. Tumor localization of boronated porphyrins in an intracerebral model of glioma

    International Nuclear Information System (INIS)

    Hill, J.S.; Kaye, A.H.; Gonzales, M.F.; Stylli, S.S.; Nakamura, Y.; Kahl, S.B.; Vardaxis, N.J.; Johnson, C.I.

    1992-01-01

    Treatment of the most common cerebral tumor, cerebral glioma, is unsatisfactory as the tumor recurs due to inadequate local control. Photodynamic therapy (PDT) and Boron Neutron Capture Therapy (BNCT) offer some promise as adjuvant treatments for cerebral glioma. Several clinical trials have been reported utilizing PDT and BNCT to treat the high grade glioma, glioblastoma multiforme. The authors have investigated the pharmacokinetic tissue distribution of the photosensitizer Haematoporphyrin derivative (HpD), the nido carboranyl porphyrin, boron tetraphenyl porphine (BTPP) and the closo carboranyl monomeric protoporphyrin (BOPP) in CBA mice bearing the intracerebral C6 glioma xenograft

  6. Porphyrin nanorods characterisation for an artificial light harvesting and energy transfer system

    CSIR Research Space (South Africa)

    Mongwaketsi, N

    2010-01-01

    Full Text Available s 1 0 h r s 1 3 h r s 1 5 h r s 1 8 h r s Porphyrin Nanorods Characterization for an Artificial Light Harvesting and Energy Transfer System Nametso Mongwaketsi1,2,3, Raymond Sparrow2, Bert Klumperman3, Malik Maaza1 1 NanoSciences Lab..., Materials Research Dept, iThemba LABS, PO Box 722, Somerset West, 7129, South Africa 2 CSIR Biosciences, PO Box 395, Pretoria, 0001, South Africa 3 Stellenbosch University, Department of Chemistry and Polymer Science, Private Bag X 1, Matieland, 7602...

  7. Photoinduced energy and electron transfer in rubrene-benzoquinone and rubrene-porphyrin systems

    KAUST Repository

    Khan, Jafar Iqbal

    2014-11-01

    Excited-state electron and energy transfer from singlet excited rubrene (Ru) to benzoquinone (BQ) and tetra-(4-aminophenyl) porphyrin (TAPP) were investigated by steady-state absorption and emission, time-resolved transient absorption, and femtosecond (fs)-nanosecond (ns) fluorescence spectroscopy. The low reduction potential of BQ provides the high probability of electron transfer from the excited Ru to BQ. Steady-state and time-resolved results confirm such an excited electron transfer scenario. On the other hand, strong spectral overlap between the emission of Ru and absorption of TAPP suggests that energy transfer is a possible deactivation pathway of the Ru excited state.

  8. Porphyrin-based magnetic nanocomposites for efficient extraction of polycyclic aromatic hydrocarbons from water samples.

    Science.gov (United States)

    Yu, Jing; Zhu, Shukui; Pang, Liling; Chen, Pin; Zhu, Gang-Tian

    2018-03-09

    Stable and reusable porphyrin-based magnetic nanocomposites were successfully synthesized for efficient extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. Meso-Tetra (4-carboxyphenyl) porphyrin (TCPP), a kind of porphyrin, can connect the copolymer after amidation and was linked to Fe 3 O 4 @SiO 2 magnetic nanospheres via cross-coupling. Several characteristic techniques such as field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry and a tensiometer were used to characterize the as-synthesized materials. The structure of the copolymer was similar to that of graphene, possessing sp 2 -conjugated carbon rings, but with an appropriate amount of delocalized π-electrons giving rise to the higher extraction efficiency for heavy PAHs without sacrificing the performance in the extraction of light PAHs. Six extraction parameters, including the TCPP:Fe 3 O 4 @SiO 2 (m:m) ratio, the amount of adsorbents, the type of desorption solvent, the desorption solvent volume, the adsorption time and the desorption time, were investigated. After the optimization of extraction conditions, a comparison of the extraction efficiency of Fe 3 O 4 @SiO 2 -TCPP and Fe 3 O 4 @SiO 2 @GO was carried out. The adsorption mechanism of TCPP to PAHs was studied by first-principles density functional theory (DFT) calculations. Combining experimental and calculated results, it was shown that the π-π stacking interaction was the main adsorption mechanism of TCPP for PAHs and that the amount of delocalized π-electrons plays an important role in the elution process. Under the optimal conditions, Fe 3 O 4 @SiO 2 -porphyrin showed good precision in intra-day (<8.9%) and inter-day (<13.0%) detection, low method detection limits (2-10 ng L -1 ), and wide linearity (10-10000 ng L -1 ). The method was applied to simultaneous analysis of 15 PAHs with

  9. Exciplex-exciplex energy transfer and annihilation in solid films of porphyrin-fullerene dyads.

    Science.gov (United States)

    Lehtivuori, Heli; Lemmetyinen, Helge; Tkachenko, Nikolai V

    2006-12-20

    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 be seen as a fast (within few picoseconds) decay of the transient absorption at excitation densities higher than 0.4 mJ/cm2. Analysis of the excitation density dependences indicates that in average four dyads are involved in the exciplex-exciplex interaction, suggesting that an exciplex-exciplex energy transfer may precede the annihilation.

  10. A Zn-porphyrin complex contributes to bright red color in Parma ham

    OpenAIRE

    Wakamatsu, J.; Nishimura, T.; Hattori, A.

    2004-01-01

    The Italian traditional dry-cured ham (Parma ham) shows a stable bright red color that is achieved without the use of nitrite and/or nitrate. In this study we examined the pigment spectroscopically, fluoroscopically and by using HPLC and ESI-HR-MASS analysis. Porphyrin derivative other than acid hematin were contained in the HCl-containing acetone extract from Parma ham. A strong fluorescence peak at 588 nm and a weak fluorescence peak at 641 nm were observed. By HPLC analysis the acetone ext...

  11. Accelerators for forming cationic technetium complexes useful as radiodiagnostic images

    International Nuclear Information System (INIS)

    Tweedle, M.F.

    1985-01-01

    This invention relates to compositions for making cationic radiodiagnostic agents and, in particular, to accelerator compounds for labelling such cationic radiodiagnostic agents, kits for preparing such 99m Tc-labelled cationic radiodiagnostic agents with technetium, and methods for labelling such cationic radiodiagnostic agents with technetium

  12. 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.

  13. Broad hexagonal columnar mesophases formation in bioinspired transition-metal complexes of simple fatty acid meta-octaester derivatives of meso-tetraphenyl porphyrins.

    Science.gov (United States)

    Wu, Bin; Chen, Keyang; Deng, Yuchen; Chen, Jian; Liu, Chengjie; Cheng, Rongshi; Chen, Dongzhong

    2015-02-23

    A series of meta-substituted fatty acid octaester derivatives and their transition-metal complexes of meso- tetraphenyl porphyrins (TPP-8OOCR, with R = C(n-1)H(2n-1), n = 8, 12, or 16) have been prepared through very simple synthesis protocols. The thermotropic phase behavior and the liquid crystalline (LC) organization structures of the synthesized porphyrin derivatives were systematically investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and variable-temperature small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) techniques. The shorter octanoic acid ester substituted porphyrin (C8-TPP) did not show liquid crystallinity and its metal porphyrins exhibited an uncommon columnar mesophase. The lauric acid octaester (C12-TPP) and the palmitic acid octaester (C16-TPP) series porphyrins generated hexagonal columnar mesophase Colh. Moreover, the metal porphyrins C12-TPPM and C16-TPPM with M = Zn, Cu, or Ni, exhibited well-organized Colh mesophases of broad LC temperature ranges increasing in the order of TPPNiacid octaester porphyrins and their metal complexes very attractive for variant applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Gas phase chemistry of N-benzylbenzamides with silver(I) cations: characterization of benzylsilver cation.

    Science.gov (United States)

    Sun, Hezhi; Jin, Zhe; Quan, Hong; Sun, Cuirong; Pan, Yuanjiang

    2015-03-07

    The benzylsilver cation which emerges from the collisional dissociation of silver(I)-N-benzylbenzamide complexes was characterized by deuterium-labeling experiments, theoretical calculations, breakdown curves and substituent effects. The nucleophilic attack of the carbonyl oxygen on an α-hydrogen results in the generation of the benzylsilver cation, which is competitive to the AgH loss with the α-hydrogen.

  15. Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities.

    Science.gov (United States)

    Rijnaarts, Timon; Huerta, Elisa; van Baak, Willem; Nijmeijer, Kitty

    2017-11-07

    Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams containing divalent ions experiences lower power densities because of both uphill transport and increased membrane resistance. In this study, we investigate the effects of divalent cations (Mg 2+ and Ca 2+ ) on RED and demonstrate the mitigation of those effects using both novel and existing commercial cation exchange membranes (CEMs). Monovalent-selective Neosepta CMS is known to block divalent cations transport and can therefore mitigate reductions in stack voltage. The new multivalent-permeable Fuji T1 is able to transport divalent cations without a major increase in resistance. Both strategies significantly improve power densities compared to standard-grade CEMs when performing RED using streams containing divalent cations.

  16. Graphene oxide vs. reduced graphene oxide as carbon support in porphyrin peroxidase biomimetic nanomaterials.

    Science.gov (United States)

    Socaci, C; Pogacean, F; Biris, A R; Coros, M; Rosu, M C; Magerusan, L; Katona, G; Pruneanu, S

    2016-02-01

    The paper describes the preparation of supramolecular assemblies of tetrapyridylporphyrin (TPyP) and its metallic complexes with graphene oxide (GO) and thermally reduced graphene oxide (TRGO). The two carbon supports are introducing different characteristics in the absorption spectra of the investigated nanocomposites. Raman spectroscopy shows that the absorption of iron-tetrapyridylporphyrin is more efficient on GO than TRGO, suggesting that oxygen functionalities are involved in the non-covalent interaction between the iron-porphyrin and graphene. The biomimetic peroxidase activity is investigated and the two iron-containing composites exhibit a better catalytic activity than each component of the assembly, and their cobalt and manganese homologues, respectively. The main advantages of this work include the demonstration of graphene oxide as a very good support for graphene-based nanomaterials with peroxidase-like activity (K(M)=0.292 mM), the catalytic activity being observed even with very small amounts of porphyrins (the TPyP:graphene ratio=1:50). Its potential application in the detection of lipophilic antioxidants (vitamin E can be measured in the 10(-5)-10(-4) M range) is also shown. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Single-Molecule Tribology: Force Microscopy Manipulation of a Porphyrin Derivative on a Copper Surface.

    Science.gov (United States)

    Pawlak, Rémy; Ouyang, Wengen; Filippov, Alexander E; Kalikhman-Razvozov, Lena; Kawai, Shigeki; Glatzel, Thilo; Gnecco, Enrico; Baratoff, Alexis; Zheng, Quanshui; Hod, Oded; Urbakh, Michael; Meyer, Ernst

    2016-01-26

    The low-temperature mechanical response of a single porphyrin molecule attached to the apex of an atomic force microscope (AFM) tip during vertical and lateral manipulations is studied. We find that approach-retraction cycles as well as surface scanning with the terminated tip result in atomic-scale friction patterns induced by the internal reorientations of the molecule. With a joint experimental and computational effort, we identify the dicyanophenyl side groups of the molecule interacting with the surface as the dominant factor determining the observed frictional behavior. To this end, we developed a generalized Prandtl-Tomlinson model parametrized using density functional theory calculations that includes the internal degrees of freedom of the side group with respect to the core and its interactions with the underlying surface. We demonstrate that the friction pattern results from the variations of the bond length and bond angles between the dicyanophenyl side group and the porphyrin backbone as well as those of the CN group facing the surface during the lateral and vertical motion of the AFM tip.

  18. Peripheral-type benzodiazepine receptor: a protein of mitochondrial outer membranes utilizing porphyrins as endogenous ligands

    International Nuclear Information System (INIS)

    Snyder, S.H.; Verma, A.; Trifiletti, R.R.

    1987-01-01

    The peripheral-type benzodiazepine receptor is a site identified by its nanomolar affinity for [ 3 H]diazepam, similar to the affinity of diazepam for the central-type benzodiazepine receptor in the brain. The peripheral type benzodiazepine receptor occurs in many peripheral tissues but has discrete localizations as indicated by autoradiographic studies showing uniquely high densities of the receptors in the adrenal cortex and in Leydig cells of the testes. Subcellular localization studies reveal a selective association of the receptors with the outer membrane of mitochondria. Photoaffinity labeling of the mitochondrial receptor with [ 3 H]flunitrazepam reveals two discrete labeled protein bands of 30 and 35 kDa, respectively. The 35-kDa band appears to be identical with the voltage-dependent anion channel protein porin. Fractionation of numerous peripheral tissues reveals a single principal endogenous ligand for the receptor, consisting of porphyrins, which display nanomolar affinity. Interactions of porphyrins with the mitochondrial receptor may clarify its physiological role and account for many pharmacological actions of benzodiazepines

  19. Nonlinear absorption dynamics using field-induced surface hopping: zinc porphyrin in water.

    Science.gov (United States)

    Röhr, Merle I S; Petersen, Jens; Wohlgemuth, Matthias; Bonačić-Koutecký, Vlasta; Mitrić, Roland

    2013-05-10

    We wish to present the application of our field-induced surface-hopping (FISH) method to simulate nonlinear absorption dynamics induced by strong nonresonant laser fields. We provide a systematic comparison of the FISH approach with exact quantum dynamics simulations on a multistate model system and demonstrate that FISH allows for accurate simulations of nonlinear excitation processes including multiphoton electronic transitions. In particular, two different approaches for simulating two-photon transitions are compared. The first approach is essentially exact and involves the solution of the time-dependent Schrödinger equation in an extended manifold of excited states, while in the second one only transiently populated nonessential states are replaced by an effective quadratic coupling term, and dynamics is performed in a considerably smaller manifold of states. We illustrate the applicability of our method to complex molecular systems by simulating the linear and nonlinear laser-driven dynamics in zinc (Zn) porphyrin in the gas phase and in water. For this purpose, the FISH approach is connected with the quantum mechanical-molecular mechanical approach (QM/MM) which is generally applicable to large classes of complex systems. Our findings that multiphoton absorption and dynamics increase the population of higher excited states of Zn porphyrin in the nonlinear regime, in particular in solution, provides a means for manipulating excited-state properties, such as transient absorption dynamics and electronic relaxation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. 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.

  1. Bulky melamine-based Zn-porphyrin tweezer as a CD probe of molecular chirality.

    Science.gov (United States)

    Petrovic, Ana G; Vantomme, Ghislaine; Negrón-Abril, Yashira L; Lubian, Elisa; Saielli, Giacomo; Menegazzo, Ileana; Cordero, Roselynn; Proni, Gloria; Nakanishi, Koji; Carofiglio, Tommaso; Berova, Nina

    2011-10-01

    The transfer of chirality from a guest molecule to an achiral host is the subject of significant interest especially when, upon chiral induction, the chiroptical response of the host/guest complex can effectively report the absolute configuration (AC) of the guest. For more than a decade, dimeric metalloporphyrin hosts (tweezers) have been successfully applied as chirality probes for determination of the AC for a wide variety of chiral synthetic compounds and natural products. The objective of this study is to investigate the utility of a new class of melamine-bridged Zn-porphyrin tweezers as sensitive AC reporters. A combined approach based on an experimental CD analysis and a theoretical prediction of the prevailing interporphyrin helicity demonstrates that these tweezers display favorable properties for chiral recognition. Herein, we discuss the application of the melamine-bridged tweezer to the chiral recognition of a diverse set of chiral guests, such as 1,2-diamines, α-amino-esters and amides, secondary alcohols, and 1,2-amino-alcohols. The bulky periphery and the presence of a rigid porphyrin linkage lead, in some cases, to a more enhanced CD sensitivity than that reported earlier with other tweezers. Copyright © 2011 Wiley-Liss, Inc.

  2. A Novel Sensor for Monitoring of Iron(III) Ions Based on Porphyrins

    Science.gov (United States)

    Vlascici, Dana; Fagadar-Cosma, Eugenia; Popa, Iuliana; Chiriac, Vlad; Gil-Agusti, Mayte

    2012-01-01

    Three A3B porphyrins with mixed carboxy-, phenoxy-, pyridyl-, and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10−7–1 × 10−1 M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples. PMID:22969395

  3. Antitumor effects evaluation of a novel porphyrin derivative in photodynamic therapy.

    Science.gov (United States)

    Li, Jian-Wei; Wu, Zhong-Ming; Magetic, Davor; Zhang, Li-Jun; Chen, Zhi-Long

    2015-12-01

    In this paper, the antitumor activity of a novel porphyrin-based photosensitizer 5,10,15,20-tetrakis[(5-diethylamino)pentyl] porphyrin (TDPP) was reported in vitro and in vivo. The photophysical and cellular properties of TDPP were investigated. The singlet oxygen generation quantum yield of TDPP was detected; it showed a high singlet oxygen quantum yield of 0.52. The intracellular distribution of photosensitizer was detected with laser scanning confocal microscopy. The efficiency of TDPP-photodynamic therapy (PDT) in vitro was analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and in situ trypan blue exclusion test. Treated with a 630-nm laser, TDPP can kill cultured human esophageal cancer cell line (Eca-109) cells and reduce the growth of Eca-109 xenograft tumors significantly in BABL/c nude mice. And histopathological study was also used to confirm the antitumor effect. It has the perspective to be developed as a new antitumor drug in photodynamic therapy and deserves further investigation.

  4. 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.

  5. Photoinduced Charge Transport Spectra for Porphyrin and Naphthalene Derivative-based Dendrimers

    Science.gov (United States)

    Park, J. H.; Wu, Y.; Parquette, J. R.; Epstein, A. J.

    2006-03-01

    Dendrimers are important chemical structures for harvesting charge. We prepared model dendrimers using two porphyrin derivatives and a naphthalene derivative. Films of these porphyrin derivatives have a strong Soret band (˜430nm) and four significant Q-bands; the naphthalene derivative has strong absorption at 365 and 383nm. Two kinds of photovoltaic cell structures [ITO/BaytronP/(thick or thin) dendrimer/Al] are constructed to investigate the optical response spectra of dendrimers under electric potential(V) on the cell (range from -1V to 2V). To obtain pure optical responses, incident light is modulated with an optical chopper and a lock-in amplifier is used to measure current (IAC) and phase (θ). For the excitation of the Soret band, IAC and θ do not change substantially with change of sign and amplitude of V. For Q-bands and naphthalene absorption bands, θ nearly follows the polarity of V on the cells and IAC is linear with V. Hence, IAC is nearly ohmic for Q- band although there are shifts due to built-in-potential. IAC for Soret band is almost same for thick and thin active layer cells. In contrast, IAC increases with thickness increase for Q bands. Mechanisms of photogeneration and charge transport will be discussed.

  6. Iron(III Fluorinated Porphyrins: Greener Chemistry from Synthesis to Oxidative Catalysis Reactions

    Directory of Open Access Journals (Sweden)

    Susana L. H. Rebelo

    2016-04-01

    Full Text Available Iron(III fluorinated porphyrins play a central role in the biomimetics of heme enzymes and enable cleaner routes to the oxidation of organic compounds. The present work reports significant improvements in the eco-compatibility of the synthesis of 5,10,15,20-tetrakis-pentafluorophenylporphyrin (H2TPFPP and the corresponding iron complex [Fe(TPFPPCl], and the use of [Fe(TPFPPCl] as an oxidation catalyst in green conditions. The preparations of H2TPFPP and [Fe(TPFPPCl] typically use toxic solvents and can be made significantly greener and simpler using microwave heating and optimization of the reaction conditions. In the optimized procedure it was possible to eliminate nitrobenzene from the porphyrin synthesis and replace DMF by acetonitrile in the metalation reaction, concomitant with a significant reduction of reaction time and simplification of the purification procedure. The Fe(IIIporphyrin is then tested as catalyst in the selective oxidation of aromatics at room temperature using a green oxidant (hydrogen peroxide and green solvent (ethanol. Efficient epoxidation of indene and selective oxidation of 3,5-dimethylphenol and naphthalene to the corresponding quinones is observed.

  7. Enhanced performance of porphyrin sensitized solar cell based on graphene quantum dots decorated photoanodes

    Science.gov (United States)

    Sehgal, Preeti; Narula, Anudeep Kumar

    2018-05-01

    Porphyrin sensitized solar cells (PSSC) has been successfully fabricated composed of graphene quantum dots (GQD) functionalized ZnO photoanodes, zinc tetrakis (4-carboxy phenyl)porphyrin (TCPPZn) as sensitizer and polypyrrole coated oxidised multiwalled carbon nanotubes (PPy/OMWCNT) as counter electrode. The effect of the concentration of GQD on the structural, morphological, photophysical and photovoltaic properties of GQD@ZnO, and GQD@ZnO/TCPPZn nanocomposites has also been investigated. Studies indicate that TCPPZn adsorbed on the surface on GQD@ZnO. Hot electron injection mechanism and multiple exciton generation from GQD to ZnO were mainly responsible for the photoexcitation response in PSSC. This study indicates that GQD can play role of sensitizer to some extent. The time decay measurements reveals the evidences of FRET mechanism, and synergistic interaction between GQD and TCPPZn. The Jsc, Voc, PCE of the corresponding PSSC devices enhanced initially and then decreased. Among all the devices fabricated, the PSSC with a 40% amount of GQD (GQD@ZnO/TCPPZn 40%) attains the best performance with the Jsc = 10.1 mA/cm2, Voc = 0.48, PCE = 2.45% FF = 0.507 higher than ZnO@TCPPZn device fabricated without GQD. Overall, this design provides a new concept for the development of photoanodes which derive better efficiency for dye sensitized solar cell (DSSC) and PSSC at economical low cost.

  8. Porphyrin-based polymeric nanostructures for light harvesting applications: Ab initio calculations

    Science.gov (United States)

    Orellana, Walter

    The capture and conversion of solar energy into electricity is one of the most important challenges to the sustainable development of mankind. Among the large variety of materials available for this purpose, porphyrins concentrate great attention due to their well-known absorption properties in the visible range. However, extended materials like polymers with similar absorption properties are highly desirable. In this work, we investigate the stability, electronic and optical properties of polymeric nanostructures based on free-base porphyrins and phthalocyanines (H2P, H2Pc), within the framework of the time-dependent density functional perturbation theory. The aim of this work is the stability, electronic, and optical characterization of polymeric sheets and nanotubes obtained from H2P and H2Pc monomers. Our results show that H2P and H2Pc sheets exhibit absorption bands between 350 and 400 nm, slightly different that the isolated molecules. However, the H2P and H2Pc nanotubes exhibit a wide absorption in the visible and near-UV range, with larger peaks at 600 and 700 nm, respectively, suggesting good characteristic for light harvesting. The stability and absorption properties of similar structures obtained from ZnP and ZnPc molecules is also discussed. Departamento de Ciencias Físicas, República 220, 037-0134 Santiago, Chile.

  9. Photovoltaic Performance of ZnO Nanosheets Solar Cell Sensitized with Beta-Substituted Porphyrin

    Directory of Open Access Journals (Sweden)

    Arumugam Mahesh

    2011-01-01

    Full Text Available The photoanode of dye-sensitized solar cell (DSSC was fabricated using two-dimensional ZnO nanosheets (2D ZnO NSs sensitized with beta-substituted porphyrins photosensitizer, and its photovoltaic performance in solid-state DSSC with TiO2 nanotubes (TiO2 TNs modified poly (ethylene oxide (PEO polymer electrolyte was studied. The ZnO NSs were synthesized through hydrothermal method and were characterized through high-resolution scanning electron microscopy (HRSEM, diffused reflectance spectra (DRS, photoluminescence spectra (PL, and X-ray diffraction (XRD analysis. The crystallinity of the polymer electrolytes was investigated using X-ray diffraction analysis. The photovoltaic performance of the beta-substituted porphyrins sensitized solar cells was evaluated under standard AM1.5G simulated illumination (100 mW cm−2. The efficiency of energy conversion from solar to electrical due to 2D ZnO NSs based DSSCs is 0.13%, which is about 1.6 times higher than that of the control DSSC using ZnO nanoparticles (ZnO NPs as photoanode (0.08%, when TiO2 NTs fillers modified PEO electrolyte was incorporated in the DSSCs. The current-voltage (- and photocurrent-time (- curves proved stable with effective collection of electrons, when the 2D ZnO nanostructured photoanode was introduced in the solid-state DSSC.

  10. Perturbations in carotenoid and porphyrin status result in differential photooxidative stress signaling and antioxidant responses.

    Science.gov (United States)

    Park, Joon-Heum; Jung, Sunyo

    2018-02-12

    We examined differential photooxidative stress signaling and antioxidant responses in rice plants treated with norflurazon (NF) and oxyfluorfen (OF), which are inhibitors of carotenoid and porphyrin biosynthesis, respectively. Plants treated with OF markedly increased levels of cellular leakage and malondialdehyde, compared with NF-treated plants, showing that OF plants suffered greater oxidative damage with respect to membrane integrity. The enhanced production of H 2 O 2 in response to OF, but not NF, indicates the important role of H 2 O 2 in activation of photooxidative stress signaling in OF plants. In response to NF and OF, the increased levels of free salicylic acid as well as maintenance of the redox ratio of ascorbate and glutathione pools to a certain level are considered to be crucial factors in the protection against photooxidation. Plants treated with OF greatly up-regulated catalase (CAT) activity and Cat transcript levels, compared with NF-treated plants. Interestingly, NF plants showed no noticeable increase in oxidative metabolism, although they did show considerable increases in ascorbate peroxidase (APX) and peroxidase activities and transcript levels of APX, as in OF plants. Our results suggest that perturbations in carotenoid and porphyrin status by NF and OF can be sensed by differential photooxidative stress signaling, such as that involving H 2 O 2 , redox state of ascorbate and glutathione, and salicylic acid, which may be responsible for at least part of the induction of ROS-scavenging enzymes. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Self-interaction corrections applied to Mg-porphyrin, C{sub 60}, and pentacene molecules

    Energy Technology Data Exchange (ETDEWEB)

    Pederson, Mark R. [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Baruah, Tunna; Basurto, Luis [Department of Physics, The University of Texas at El Paso, El Paso, Texas 79968 (United States); Kao, Der-you [Department of Mechanical and Aerospace Engineering, George Washington University, Washington, DC 20052 (United States)

    2016-04-28

    We have applied a recently developed method to incorporate the self-interaction correction through Fermi orbitals to Mg-porphyrin, C{sub 60}, and pentacene molecules. The Fermi-Löwdin orbitals are localized and unitarily invariant to the Kohn-Sham orbitals from which they are constructed. The self-interaction-corrected energy is obtained variationally leading to an optimum set of Fermi-Löwdin orbitals (orthonormalized Fermi orbitals) that gives the minimum energy. A Fermi orbital, by definition, is dependent on a certain point which is referred to as the descriptor position. The degree to which the initial choice of descriptor positions influences the variational approach to the minimum and the complexity of the energy landscape as a function of Fermi-orbital descriptors is examined in detail for Mg-porphyrin. The applications presented here also demonstrate that the method can be applied to larger molecular systems containing a few hundred electrons. The atomization energy of the C{sub 60} molecule within the Fermi-Löwdin-orbital self-interaction-correction approach is significantly improved compared to local density approximation in the Perdew-Wang 92 functional and generalized gradient approximation of Perdew-Burke-Ernzerhof functionals. The eigenvalues of the highest occupied molecular orbitals show qualitative improvement.

  12. A novel sensor for monitoring of iron(III) ions based on porphyrins.

    Science.gov (United States)

    Vlascici, Dana; Fagadar-Cosma, Eugenia; Popa, Iuliana; Chiriac, Vlad; Gil-Agusti, Mayte

    2012-01-01

    Three A(3)B porphyrins with mixed carboxy-, phenoxy-, pyridyl-, and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10(-7)-1 × 10(-1) M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples.

  13. Self-interaction corrections applied to Mg-porphyrin, C60, and pentacene molecules

    International Nuclear Information System (INIS)

    Pederson, Mark R.; Baruah, Tunna; Basurto, Luis; Kao, Der-you

    2016-01-01

    We have applied a recently developed method to incorporate the self-interaction correction through Fermi orbitals to Mg-porphyrin, C 60 , and pentacene molecules. The Fermi-Löwdin orbitals are localized and unitarily invariant to the Kohn-Sham orbitals from which they are constructed. The self-interaction-corrected energy is obtained variationally leading to an optimum set of Fermi-Löwdin orbitals (orthonormalized Fermi orbitals) that gives the minimum energy. A Fermi orbital, by definition, is dependent on a certain point which is referred to as the descriptor position. The degree to which the initial choice of descriptor positions influences the variational approach to the minimum and the complexity of the energy landscape as a function of Fermi-orbital descriptors is examined in detail for Mg-porphyrin. The applications presented here also demonstrate that the method can be applied to larger molecular systems containing a few hundred electrons. The atomization energy of the C 60 molecule within the Fermi-Löwdin-orbital self-interaction-correction approach is significantly improved compared to local density approximation in the Perdew-Wang 92 functional and generalized gradient approximation of Perdew-Burke-Ernzerhof functionals. The eigenvalues of the highest occupied molecular orbitals show qualitative improvement.

  14. Evidence for polar porphyrins of bacterial and algal origin in oil shale

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo, R.; Callot, H.J.; Albrecht, P.

    1986-04-01

    The major part of the porphyrins of the immature Messel oil shale is composed of monocarboxylic acids (C/sub 30/-C/sub 36/) essentially complexed with nickel. These acids were separated as methyl esters by reverse phase h.p.l.c. and nine components characterized by mass and NMR spectroscopy. Structural assignments were supported by synthesis of several members and nuclear Overhauser effect experiments. Besides a major component of the DPEP series, this fraction contained other members belonging to the phyllo- and etioporphyrin series, as well as to a novel chlorophyll C derived series typical of algae. Furthermore the identification of several higher homologues (C/sub 34/-C/sub 36/) of the DPEP series, structurally related to the bacteriochlorophylls, reflects the bacterial input. The characterization of a series of petroporphyrinic acids from the polar fraction of the Messel oil shale confirms the chlorophyllic (a+b,c) origin of these porphyrins. It furthermore implies that most of the characterized petroporphyrins and the survival of carboxylic functions in this class of compounds under mild diagenetic conditions. It furthermore implies that most of the characterized petroporphyrins in Messel shale originate from photosynthetic bacteria and microscopic algae.

  15. Body burden of hexachlorobenzene in suckling rats and its effects on various organs and on liver porphyrin accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, C E; Grant, D L; Shields, J B

    1975-01-01

    The hexachlorobenzene (HCB) and porphyrin accumulation in the organs of 18-day-old Wistar rats, whose mothers were fed a diet containing 80 ppM HCB, were studied. Among the organs examined, the highest HCB residue was in the liver greater than kidney greater than or equal to lung greater than brain greater than spleen greater than heart. The porphyrin level in the liver of the HCB-treated group was approximately 2.5 fold greater than that in the control liver. About equal porphyrin concentrations were found in the male and female pups. The analysis of variance indicated the liver weight was significantly increased by the HCB-treatment. On the contrary, the weights of the kidney, brain, spleen, and heart were significantly reduced. Sex did not influence the organ weight except that of the brain. The results suggested that accumulation of HCB in different organs and porphyrin in the liver of suckling Wistar rats was about equal for the males and females.

  16. 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.

  17. Properties of halogenated and sulfonated porphyrins relevant for the selection of photosensitizers in anticancer and antimicrobial therapies.

    Directory of Open Access Journals (Sweden)

    Barbara Pucelik

    Full Text Available The impact of substituents on the photochemical and biological properties of tetraphenylporphyrin-based photosensitizers for photodynamic therapy of cancer (PDT as well as photodynamic inactivation of microorganisms (PDI was examined. Spectroscopic and physicochemical properties were related with therapeutic efficacy in PDT of cancer and PDI of microbial cells in vitro. Less polar halogenated, sulfonamide porphyrins were most readily taken up by cells compared to hydrophilic and anionic porphyrins. The uptake and PDT of a hydrophilic porphyrin was significantly enhanced with incorporation in polymeric micelles (Pluronic L121. Photodynamic inactivation studies were performed against Gram-positive (S. aureus, E. faecalis, Gram-negative bacteria (E. coli, P. aeruginosa, S. marcescens and fungal yeast (C. albicans. We observed a 6 logs reduction of S. aureus after irradiation (10 J/cm2 in the presence of 20 μM of hydrophilic porphyrin, but this was not improved with incorporation in Pluronic L121. A 2-3 logs reduction was obtained for E. coli using similar doses, and a decrease of 3-4 logs was achieved for C. albicans. Rational substitution of tetraphenylporphyrins improves their photodynamic properties and informs on strategies to obtain photosensitizers for efficient PDT and PDI. However, the design of the photosensitizers must be accompanied by the development of tailored drug formulations.

  18. Spectroscopy and photophysics of self-organized zinc porphyrin nanolayers. 1. Optical spectroscopy of excitonic interactions involving the soret band

    NARCIS (Netherlands)

    Donker, H.; Koehorst, R.B.M.; Schaafsma, T.J.

    2005-01-01

    The photophysical properties of excited singlet states of zinc tetra-(p-octylphenyl)-porphyrin in 5-25-nm-thick films spin-coated onto quartz slides have been investigated by optical spectroscopy. Analysis of the polarized absorption spectra using a dipole-dipole exciton model with two mutually

  19. Doubly and triply linked porphyrin-perylene monoimides as near IR dyes with large dipole moments and high photostability

    KAUST Repository

    Jiao, Chongjun; Huang, Kuo-Wei; Chi, Chunyan; Wu, Jishan

    2011-01-01

    Doubly and triply linked porphyrin-perylene monoimides 3 and 4, with extraordinary stability, large dipole moments, and strong near IR absorption, were prepared by means of one-pot oxidative cyclodehydrogenation promoted by FeCl 3. © 2010 American

  20. 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

  1. Doubly and triply linked porphyrin-perylene monoimides as near IR dyes with large dipole moments and high photostability

    KAUST Repository

    Jiao, Chongjun

    2011-01-21

    Doubly and triply linked porphyrin-perylene monoimides 3 and 4, with extraordinary stability, large dipole moments, and strong near IR absorption, were prepared by means of one-pot oxidative cyclodehydrogenation promoted by FeCl 3. © 2010 American Chemical Society.

  2. p38 MAPK plays an essential role in apoptosis induced by photoactivation of a novel ethylene glycol porphyrin derivative

    Czech Academy of Sciences Publication Activity Database

    Králová, Jarmila; Dvořák, Michal; Koc, Michal; Král, V.

    2008-01-01

    Roč. 27, č. 21 (2008), s. 3010-3020 ISSN 0950-9232 R&D Projects: GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z50520514 Keywords : porphyrin * photoactivation * apoptosis of tumour cells * p38 MAPK, caspase * lysosome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.216, year: 2008

  3. HALOGENATED AROMATIC HYDROCARBON-MEDIATED PORPHYRIN ACCUMULATION AND INDUCTION OF CYTOCHROME P4501A IN CHICKEN EMBRYO HEPATOCYTES. (R823889)

    Science.gov (United States)

    Concentration-dependent induction of cytochrome P4501A (CYP1A) and intracellular porphyrin accumulation were observed following treatment of chicken embryo hepatocyte (CEH) cultures with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 3,3',4,4'...

  4. 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.

  5. Aggregation and metal-complexation behaviour of THPP porphyrin in ethanol/water solutions as function of pH

    Science.gov (United States)

    Zannotti, Marco; Giovannetti, Rita; Minofar, Babak; Řeha, David; Plačková, Lydie; D'Amato, Chiara A.; Rommozzi, Elena; Dudko, Hanna V.; Kari, Nuerguli; Minicucci, Marco

    2018-03-01

    The effect of pH change on 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (THPP) with its aggregation as function of water-ethanol mixture was studied with UV-vis, fluorescence, Raman and computational analysis. In neutral pH, THPP was present as free-base and, increasing the water amount, aggregation occurred with the formation of H- and J-aggregates. The aggregation constant and the concentration of dimers were calculated, other information about the dimer aggregation were evaluated by computational study. In acidic pH, by the insertions of two hydrogens in the porphyrin rings, the porphyrin changed its geometry with a ring deformation confirmed by red-shifted spectrum and quenching in fluorescence; at this low pH, increasing the water amount, the acidic form (THPPH2)2 + resulted more stable due to a polar environment with stronger interaction by hydrogen bonding. In basic pH, reached by NH4OH, THPP porphyrin was able to react with alkali metals in order to form sitting-atop complex (M2THPP) confirmed by the typical absorption spectrum of metallo-porphyrin, Raman spectroscopy and by computational analysis.

  6. Forging Colloidal Nanostructures via Cation Exchange Reactions.

    Science.gov (United States)

    De Trizio, Luca; Manna, Liberato

    2016-09-28

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field.

  7. Forging Colloidal Nanostructures via Cation Exchange Reactions

    Science.gov (United States)

    2016-01-01

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field. PMID:26891471

  8. 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

  9. Cooperative effects in CdSe/ZnS-PEGOH quantum dot luminescence quenching by a water soluble porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Borissevitch, I.E., E-mail: iourib@ffclrp.usp.br [Departamento de Fisica, Faculdade de Filosofia Ciencia e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes 3900, Ribeirao Preto, SP (Brazil); Parra, G.G. [Departamento de Fisica, Faculdade de Filosofia Ciencia e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes 3900, Ribeirao Preto, SP (Brazil); Zagidullin, V.E.; Lukashev, E.P.; Knox, P.P.; Paschenko, V.Z.; Rubin, A.B. [Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Vorobyovy Gory, 119991 Moscow (Russian Federation)

    2013-02-15

    In this work we report on the study of the interaction of CdSe/ZnS-PEGOH 570 Quantum Dot (QD) with negatively charged meso-tetrakis(p-sulfonato-phenyl)porphyrin (TPPS{sub 4}) using optical absorption and fluorescence spectroscopies accompanied with time resolved 'single photon counting' and dynamic and resonance light scattering techniques. In the steady-state experiments the QD luminescence quenching by TPPS{sub 4} was well approximated by a square law. In the time-resolved experiments we observed a typical multi-exponential luminescence decay curve, successfully fitted by a bi-exponential approximation. At QD interaction with porphyrin the time quenching of both components was described by a linear Stern-Volmer dependence. The discrepancy between Stern-Volmer dependences in the steady-state and time resolved experiments may be due to formation of mixed m(TPPS{sub 4})+n(QD) complexes, in which one TPPS{sub 4} molecule can quench several excited QDs. This idea is in accordance with the dynamic and resonance light scattering data, which demonstrate an increase of the scattering particle size at the TPPS{sub 4} addition to QD solutions. - Highlights: Black-Right-Pointing-Pointer Quantum Dot luminescence quenching by TPPS porphyrin was studied in water solutions. Black-Right-Pointing-Pointer The size of particles in QD solutions possessed increase at the TPPS4 addition. Black-Right-Pointing-Pointer Quenching of the QD luminescence by TPPS4 is realized in contact QD-porphyrin complexes. Black-Right-Pointing-Pointer The formation of mixed quantum dot-porphyrin aggregates takes place.

  10. The Synthesis and Photophysical Characterization of Porphyrin Photoactive Materials for Use as Sensitizers in Organic Photovoltaics and Photodynamic Therapy

    Science.gov (United States)

    Marin, Dawn Marie

    Solar energy conversion and photodynamic therapy (PDT) are very different applications. However, both utilize very similar photoactive molecules called porphyrins. Porphyrins are structural analogs of chlorophyll and also function as prosthetic groups in some biological enzymes. Understanding the structure/function relationship of these molecules is crucial for enhancing the energy generation efficiency of molecular solar cells and improving chemotherapeutic activity in PDT. In this dissertation, two approaches were applied with the goal of increasing the efficiency of molecular semiconductors for these applications: the heavy atom effect and donor-acceptor molecules. We enhanced the efficiency of triplet excited state formation and singlet oxygen generation for porphyrin sensitizers using the heavy atom effect. The heavy atom effect induces spin-orbit coupling to promote intersystem crossing into the triplet state. In this study, a carbomethoxyphenyl substituent was replaced with either a bromophenyl or an iodophenyl substituent on 5,10,15,20-tetrakis(4-carbomethoxyphenyl)porphyrin. The longer lifetimes obtained from the increase in the triplet excited state allow for longer exciton diffusion lengths and lower recombination rates in photovoltaics. Also, the enhanced intersystem crossing is beneficial for photodynamic therapy because it increases singlet oxygen generation, which destroys tumor cells. Optimizing photovoltaic performance and PDT efficacy can also be accomplished with donor-acceptor molecules because they have extended electronic pi bond delocalization across the molecule, which causes the molecule to absorb longer wavelengths of light. Donor-acceptor molecules should produce photovoltaic devices that absorb more of the solar spectrum and produce sensitizers that absorb wavelengths of light that can penetrate through tissues. Donor-acceptor molecules were synthesized using 5,15-bis(4-carbomethoxyphenyl)porphyrin as the acceptor and thiazolo[5,4-d

  11. Cooperative effects in CdSe/ZnS-PEGOH quantum dot luminescence quenching by a water soluble porphyrin

    International Nuclear Information System (INIS)

    Borissevitch, I.E.; Parra, G.G.; Zagidullin, V.E.; Lukashev, E.P.; Knox, P.P.; Paschenko, V.Z.; Rubin, A.B.

    2013-01-01

    In this work we report on the study of the interaction of CdSe/ZnS-PEGOH 570 Quantum Dot (QD) with negatively charged meso-tetrakis(p-sulfonato-phenyl)porphyrin (TPPS 4 ) using optical absorption and fluorescence spectroscopies accompanied with time resolved “single photon counting” and dynamic and resonance light scattering techniques. In the steady-state experiments the QD luminescence quenching by TPPS 4 was well approximated by a square law. In the time-resolved experiments we observed a typical multi-exponential luminescence decay curve, successfully fitted by a bi-exponential approximation. At QD interaction with porphyrin the time quenching of both components was described by a linear Stern–Volmer dependence. The discrepancy between Stern–Volmer dependences in the steady-state and time resolved experiments may be due to formation of mixed m(TPPS 4 )+n(QD) complexes, in which one TPPS 4 molecule can quench several excited QDs. This idea is in accordance with the dynamic and resonance light scattering data, which demonstrate an increase of the scattering particle size at the TPPS 4 addition to QD solutions. - Highlights: ► Quantum Dot luminescence quenching by TPPS porphyrin was studied in water solutions. ► The size of particles in QD solutions possessed increase at the TPPS4 addition. ► Quenching of the QD luminescence by TPPS4 is realized in contact QD–porphyrin complexes. ► The formation of mixed quantum dot–porphyrin aggregates takes place.

  12. Isolation of an oxomanganese(V) porphyrin intermediate in the reaction of a manganese(III) porphyrin complex and H2O2 in aqueous solution.

    Science.gov (United States)

    Nam, Wonwoo; Kim, Inwoo; Lim, Mi Hee; Choi, Hye Jin; Lee, Je Seung; Jang, Ho G

    2002-05-03

    The reaction of [Mn(TF(4)TMAP)](CF(3)SO(3))(5) (TF(4)TMAP=meso-tetrakis(2,3,5,6-tetrafluoro-N,N,N-trimethyl-4-aniliniumyl)porphinato dianion) with H(2)O(2) (2 equiv) at pH 10.5 and 0 degrees C yielded an oxomanganese(V) porphyrin complex 1 in aqueous solution, whereas an oxomanganese(IV) porphyrin complex 2 was generated in the reactions of tert-alkyl hydroperoxides such as tert-butyl hydroperoxide and 2-methyl-1-phenyl-2-propyl hydroperoxide. Complex 1 was capable of epoxidizing olefins and exchanging its oxygen with H(2) (18)O, whereas 2 did not epoxidize olefins. From the reactions of [Mn(TF(4)TMAP)](5+) with various oxidants in the pH range 3-11, the O-O bond cleavage of hydroperoxides was found to be sensitive to the hydroperoxide substituent and the pH of the reaction solution. Whereas the O-O bond of hydroperoxides containing an electron-donating tert-alkyl group is cleaved homolytically, an electron-withdrawing substituent such as an acyl group in m-chloroperoxybenzoic acid (m-CPBA) facilitates O-O bond heterolysis. The mechanism of the O-O bond cleavage of H(2)O(2) depends on the pH of the reaction solution: O-O bond homolysis prevails at low pH and O-O bond heterolysis becomes a predominant pathway at high pH. The effect of pH on (18)O incorporation from H(2) (18)O into oxygenated products was examined over a wide pH range, by carrying out the epoxidation of carbamazepine (CBZ) with [Mn(TF(4)TMAP)](5+) and KHSO(5) in buffered H(2) (18)O solutions. A high proportion of (18)O was incorporated into the CBZ-10,11-oxide product at all pH values but this proportion was not affected significantly by the pH of the reaction solution.

  13. Restructuring of a peat in interaction with multivalent cations: effect of cation type and aging time.

    Directory of Open Access Journals (Sweden)

    Yamuna Kunhi Mouvenchery

    Full Text Available It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM molecules via cation bridges (CaB. The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al(3+, Ca(2+ or Na(+, respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>>2 h than deprotonation of functional groups (<2 h and was described by a Langmuir model. The maximum uptake increased with pH of cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB and molecular mobility of water (NMR analysis suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is

  14. Adsorption of cationic amylopectin on microcrystalline cellulose.

    NARCIS (Netherlands)

    Steeg, van de H.G.M.; Keizer, de A.; Cohen Stuart, M.A.; Bijsterbosch, B.H.

    1993-01-01

    The effects of electrolyte concentration and pH on the adsorption of cationic amylopectin on microcrystalline cellulose were investigated. The adsorbed amount in the pseudo-plateau of the isotherm showed a maximum as a function of the electrolyte concentration. We compared the data with a recent

  15. Alkynylcarbenium ions and related unsaturated cations

    Energy Technology Data Exchange (ETDEWEB)

    Lukyanov, Sergey M; Koblik, Alla V; Muradyan, Lyudmila A [Institute of Physical and Organic Chemistry, Rostov State University, Rostov-on-Don (Russian Federation)

    1998-10-31

    Published data on carbenium ions containing carbon-carbon triple bonds both directly conjugated with the carbenium centre and separated from it are surveyed and described systematically. Ammonium, diazonium, iminium, phosphonium and iodonium cations containing alkynyl groups, which can be regarded as heteroanalogues of alkynylcarbenium ions, are also considered. The bibliography includes 283 references.

  16. Alkynylcarbenium ions and related unsaturated cations

    International Nuclear Information System (INIS)

    Lukyanov, Sergey M; Koblik, Alla V; Muradyan, Lyudmila A

    1998-01-01

    Published data on carbenium ions containing carbon-carbon triple bonds both directly conjugated with the carbenium centre and separated from it are surveyed and described systematically. Ammonium, diazonium, iminium, phosphonium and iodonium cations containing alkynyl groups, which can be regarded as heteroanalogues of alkynylcarbenium ions, are also considered. The bibliography includes 283 references

  17. Effect of cations on the hydrated proton.

    Science.gov (United States)

    Ottosson, Niklas; Hunger, Johannes; Bakker, Huib J

    2014-09-17

    We report on a strong nonadditive effect of protons and other cations on the structural dynamics of liquid water, which is revealed using dielectric relaxation spectroscopy in the frequency range of 1-50 GHz. For pure acid solutions, protons are known to have a strong structuring effect on water, leading to a pronounced decrease of the dielectric response. We observe that this structuring is reduced when protons are cosolvated with salts. This reduction is exclusively observed for combinations of protons with other ions; for all studied solutions of cosolvated salts, the effect on the structural dynamics of water is observed to be purely additive, even up to high concentrations. We derive an empirical model that quantitatively describes the nonadditive effect of cosolvated protons and cations. We argue that the effect can be explained from the special character of the proton in water and that Coulomb fields exerted by other cations, in particular doubly charged cations like Mg(2+)aq and Ca(2+)aq, induce a localization of the H(+)aq hydration structures.

  18. Mixed cation effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.

    , network structure, and the resistances associated with the deformation processes in mixed cation glasses by partially substituting magnesium for calcium and calcium for lithium in sodium aluminosilicate glasses. We use Raman and 27Al NMR spectroscopies to obtain insights into the structural...

  19. Cationic flotation of some lithium ores

    International Nuclear Information System (INIS)

    Valadao, G.E.S.; Peres, A.E.C.; Silva, H.C. da

    1984-01-01

    The cationic flotation of some lithium ores (spodumene, amblygonite, petalite, lepidolite) is studied by the measure of zeta potential and micro-flotation tests in Hallimond tube. The effect of some modifier agents (corn starch, meta sodium silicate) on the lithium flotation is studied. (M.A.C.) [pt

  20. Letter: OCCO*+, NNCO*+ and NNNN*+ radical cations.

    Science.gov (United States)

    Flammang, R; Srinivas, R; Nguyen, M T; Gerbaux, P

    2007-01-01

    Chemical ionization of a mixture of nitrogen and carbon monoxide produces three stable isobaric species at m/z 56: OCCO, OCNN and NNNN radical cations. Separated at increased resolution, these ions are readily identified by collisional activation. Neutralization-reionization experiments performed on two different mass spectrometers have not allowed the detection of any recovery signals for the corresponding neutrals.