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Sample records for benzoxazoles

  1. Benzoxazoles and oxazolopyridines in medicinal chemistry studies

    DEFF Research Database (Denmark)

    Demmer, Charles S; Bunch, Lennart

    2015-01-01

    The benzoxazole heterocycle is often found in ligands targeting a plethora of receptors and enzymes. By analysis of published X-ray structures, this review aims at highlighting key interactions which the benzoxazole may engage in with its host protein. Furthermore, bioavailability, metabolism and...... chemistry studies....

  2. SYNTHESIS THROUGH MICROWAVE IRRADIATION, CHARACTERIZATION AND EVALUATION OF ANTIMICROBIAL ACTIVITY OF 2-PHENYL-1, 3-BENZOXAZOLE DERIVATIVES

    Directory of Open Access Journals (Sweden)

    Tariq Sana

    2012-09-01

    Full Text Available A series of 2-phenyl-1,3-benzoxazoles were synthesized by the reaction of 2-aminophenol and acyl chlorides using microwave irradiation. Purity of compounds was determined by TLC. All the synthesized compounds were characterized by spectral analysis (FTIR, 1H-NMR . The compounds were evaluated for in vitro antimicrobial activity against Bacillus pumilus, Bacillus subtilis (Gram positive; Escherichia coli, Pseudomonas aeruginosa (Gram negative and Candida albicans and Aspergillus niger by agar-well diffusion method at 2.5, 5, 10mg/ml. Compounds 2-(2-methoxyphenyl-1,3-benzoxazole, 2-(4-bromophenyl-1,3-benzoxazole, 2-(3-cholorophenyl-1,3-benzoxazole, 2-(2-nitrophenyl-1,3-benzoxazole have been found to have good antibacterial activity. Compounds 2-pheny-1,3-benzoxazole, 2-(4-bromophenyl-1,3-benzoxazole, were potent antifungal compounds amongst the series.

  3. Novel benzoxazole inhibitors of mPGES-1.

    Science.gov (United States)

    Kablaoui, Natasha; Patel, Snahel; Shao, Jay; Demian, Douglas; Hoffmaster, Keith; Berlioz, Francioise; Vazquez, Michael L; Moore, William M; Nugent, Richard A

    2013-02-01

    A novel series of potent benzoxazole mPGES-1 inhibitors has been derived from a hit from a high throughput screen. Compound 37 displays mPGES-1 inhibition in an enzyme assay (0.018 μM) and PGE-2 inhibition in a cell-based assay (0.034 μM). It demonstrates 500- and 2500-fold selectivity for mPGES-1 over COX-2 and 6-keto PGF-1α, respectively. In vivo PK studies in dogs demonstrate 55% oral bioavailability and an 7 h half-life. PMID:23266122

  4. Efficient Syntheses of 2-Substituted Benzimidazoles and Benzoxazoles from β-Keto Esters

    Institute of Scientific and Technical Information of China (English)

    XIAO Li-wei; ZHANG Min; SUN Wen-hua

    2011-01-01

    An efficient synthetic method was developed to synthesize 2-substituted benzimidazoles and benzoxazoles withβ-keto esters as starting materials under mild reaction conditions, during which other functional groups are bearable from reactants to products.

  5. A chemometric approach for prediction of antifungal activity of some benzoxazole derivatives against Candida albicans

    Directory of Open Access Journals (Sweden)

    Podunavac-Kuzmanović Sanja O.

    2012-01-01

    Full Text Available The purpose of the article is to promote and facilitate prediction of antifungal activity of the investigated series of benzoxazoles against Candida albicans. The clinical importance of this investigation is to simplify design of new antifungal agents against the fungi which can cause serious illnesses in humans. Quantitative structure activity relationship analysis was applied on nineteen benzoxazole derivatives. A multiple linear regression (MLR procedure was used to model the relationships between the molecular descriptors and the antifungal activity of benzoxazole derivatives. Two mathematical models have been developed as a calibration models for predicting the inhibitory activity of this class of compounds against Candida albicans. The quality of the models was validated by the leave-one-out technique, as well as by the calculation of statistical parameters for the established model. [Projekat Ministarstva nauke Republike Srbije, br. 172012 i br. 172014

  6. Microwave-assisted one-pot synthesis of benzothiazole and benzoxazole libraries as analgesic agents

    Indian Academy of Sciences (India)

    C Praveen; A Nandakumar; P Dheenkumar; D Muralidharan; P T Perumal

    2012-05-01

    Microwave-assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved. Twenty compounds have been investigated for their analgesic activity and showed moderate to good activity.

  7. Synthesis of substituted benzoxazoles by the iron(Ⅲ)-catalyzed aerobic oxidation process

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The FeCl3-catalyzed aerobic oxidation process for the synthesis of benzoxazoles,benzothiazole and benzimidazole has been discovered.This method has proved to be effective to a wide range of substrates,and it has been applied for the synthesis of JTP-426467.

  8. Discovery of new antitubercular agents by combining pyrazoline and benzoxazole pharmacophores: design, synthesis and insights into the binding interactions

    Czech Academy of Sciences Publication Activity Database

    Rana, D. N.; Chhabria, M. T.; Shah, N. K.; Brahmkshatriya, Pathik

    2014-01-01

    Roč. 23, č. 5 (2014), s. 2218-2228. ISSN 1054-2523 Institutional support: RVO:61388963 Keywords : antitubercular * benzoxazole * interaction energy * molecular docking * pharmacophore * pyrazoline Subject RIV: CC - Organic Chemistry Impact factor: 1.402, year: 2014

  9. Synthesis and Biological Evaluation of Novel 5,7-Dichloro-1,3-benzoxazole Derivatives

    Directory of Open Access Journals (Sweden)

    N. D. Jayanna

    2013-01-01

    Full Text Available A new class of 5,7-dichloro-1,3-benzoxazole derivatives 4–11 were synthesized by fusing 5,7-dichloro-2-hydrazino-1,3-benzoxazole 3 nucleus with aliphatic acids, active methylene compounds, and with selected esters to form heterocyclic ring systems like 1,2,4-triazoles, pyrazoles, and triazine moieties. The compound 3 on diazotization reaction affords the tetrazole compound. The synthesized compounds were characterized by 1H NMR, IR, Mass, and 13C NMR spectral data and screened for cytotoxic, antimicrobial, antioxidant, and antilipase activities. The compounds 4, 5, and 8 have shown significant antimicrobial activities, whereas compounds 6 and 8 have been emerged as leading cytotoxic agents. The compounds 9, 10, and 11 were found to be strong enzyme inhibitors.

  10. Effect of Solvent on Nonlinear Refractive Index of 2-(2‧-HYDROXYPHENYL) Benzoxazole

    Science.gov (United States)

    ZHANG, GUILAN; XIONG, FEIBING; ZHANG, BAO; TANG, GUOQING; CHEN, WENJU; WANG, LIANYING; BAI, YUBAI

    Nonlinear refractive indexes n2 of 2-(2‧-hydroxyphenyl) benzoxazole (HBO) in three species of solvent (cyclohexane, ethanol and dimethyl sulfoxide) have been determined by using the Z-scan technique. The experimental results show that the n2 of HBO is strongly dependent on the polarity of the solvent. Through the study on the absorption and fluorescence spectra of HBO in different solvents, we regard that the principal origin of the nonlinear refractive index of HBO is not the thermal effect because of absorption of incident light but the excited state intramolecular proton transfer of HBO under the incident light.

  11. A pilot study of the novel J-PET plastic scintillator with 2-(4-styrylphenyl)benzoxazole as a wavelength shifter

    CERN Document Server

    Wieczorek, A; Niedźwiecki, Sz; Bednarski, T; Białas, P; Czerwiński, E; Danel, A; Gajos, A; Gruntowski, A; Kamińska, D; Kapłon, Ł; Kochanowski, A; Korcyl, G; Kowal, J; Kowalski, P; Kozik, T; Krzemień, W; Kubicz, E; Molenda, M; Pałka, M; Raczyński, L; Rudy, Z; Rundel, O; Salabura, P; Sharma, N G; Silarski, M; Słomski, A; Smyrski, J; Strzelecki, A; Uchacz, T; Wiślicki, W; Zieliński, M; Zoń, N

    2015-01-01

    For the first time a molecule of 2-(4-styrylphenyl)benzoxazole containing benzoxazole and stilbene groups is applied as a scintillator dopant acting as a wavelength shifter. In this article a light yield of the plastic scintillator, prepared from styrene doped with 2 wt% of 2,5-diphenylbenzoxazole and 0.03 wt% of 2-(4-styrylphenyl)benzoxazole, is determined to be as large as 60% $\\pm$ 2% of the anthracene light output. There is a potential to improve this value in the future by the optimization of the additives concentrations.

  12. Improvement of surface wetting properties of poly(p-phenylene benzoxazole) by incorporation of ionic groups

    International Nuclear Information System (INIS)

    Modified poly(p-phenylene benzoxazole), SPBO, containing ionic sulfonate groups was synthesized by polycondensation of the corresponding monomers in polyphosphoric acid. SPBO fiber was spun via a dry-jet wet-spinning technique. The wetting property of poly(p-phenylene benzoxazole) (PBO) fiber and SPBO fiber were measured by contact angle analysis, and the interfacial shear strength (IFSS) between fibers and epoxy was determined by microbond pull-out testing. The contact angles of water and ethanol on SPBO fiber surface get smaller, and the wetting process becomes faster. The surface free energy of SPBO fiber increases to 38.9 mJ m-2, which is 9.6% higher than that of PBO fiber. Furthermore the ionic introducing leads to a 23% increase in IFSS from 8.2 MPa for PBO/epoxy to 10.1 MPa for SPBO/epoxy. It could be expected that the failure mode may change from fiber/matrix interface adhesive failure to partly cohesive failure mode

  13. Fluorescence characteristics and photostability of benzoxazole derived donor-acceptor dyes in constrained media.

    Science.gov (United States)

    Fayed, Tarek A; Etaiw, Safaa El-Din H

    2006-10-01

    The spectroscopic properties and photoreactivity of 2-(4-dimethylaminostryl)benzoxazole and its butadienyl analogue (abbreviated as DMASBO and BODB, respectively) were investigated in thin films of PS, PMMA and PVA polymer matrices as well as immobilized on silica surface. The experimental results showed that the investigated benzoxazole derivatives are sensitive to the polarity of its microenvironment even in the glassy matrices and in the solid state. The micropolarity of PVA and silica surface is greater than that of PMMA and PS. The combined results of fluorescence quantum yield and photoisomerization indicated that the size of the free volume within the polymer matrix influence strongly the photochemical reactivity of the used dyes. In PVA, which offers the smaller free volume, the photoreaction is totally blocked while the fluorescence yield is extremely enhanced relative to those in solutions and other polymer matrices. This is associated with an emission of green laser from DMASBO-PVA doped film when pumped by nitrogen laser (337 nm). The results showed that the present dyes are excellent probes for non-fluorescent systems presenting constrained geometry. The spectra of amorphous solid thin films of both dyes were also measured and show large red shifts relative to those in solutions indicating symmetric aggregation of molecules in the solid crystals. PMID:16500138

  14. Synthesis and pharmacological evaluation of piperidine (piperazine)-substituted benzoxazole derivatives as multi-target antipsychotics.

    Science.gov (United States)

    Huang, Ling; Zhang, Wenjun; Zhang, Xiaohua; Yin, Lei; Chen, Bangyin; Song, Jinchun

    2015-11-15

    The present study describes the optimization of a series of novel benzoxazole-piperidine (piperazine) derivatives combining high dopamine D2 and serotonin 5-HT1A, 5-HT2A receptor affinities. Of these derivatives, the pharmacological features of compound 29 exhibited high affinities for the DA D2, 5-HT1A and 5-HT2A receptors, but low affinities for the 5-HT2C and histamine H1 receptors and human ether-a-go-go-related gene (hERG) channels. Furthermore, compound 29 reduced apomorphine-induced climbing and 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI)-induced head twitching without observable catalepsy, even at the highest dose tested. Thus, compound 29 is a promising candidate as a multi-target antipsychotic treatment. PMID:26483200

  15. Triplet-triplet absorption of 2-(2'-hydroxyphenyl) benzoxazole (HBO) in polar solvents

    Science.gov (United States)

    Yang, Guoqiang; Morlet-Savary, Fabrice; Peng, Zhaokui; Wu, Shikang; Fouassier, Jean-Pierre

    1996-07-01

    The transient TT absorption spectra of 2-(2'-hydroxyphenyl) benzoxazole (HBO) have been measured in liquid polar solvents and in polymethylthacrylate. In non-protonic polar solvents the main TT absorption is from the keto form of the compound ( 3K ∗). With a triplet sensitizer the compound just gives a TT absorption of its enol from ( 3E ∗) after triplet energy transfer from the sensitizer to HBO. The excited state intramolecular proton transfer (ESIPT) from the enol form to keto form occurs just in the singlet state. The protonic solvent can break the intramolecular hydrogen bond of HBO and decrease the ESIPT process. In solid solution both 3E ∗ and 3K ∗ can be formed and the TT absorptions were detected because of the inhibition of the rotational conformation transfer.

  16. Synthesis and in vitro antibacterial and antifungal activities of benzoxazole derivatives

    International Nuclear Information System (INIS)

    The in vitro antibacterial and antifungal activities of twenty-nine (29) benzoxazole derivatives were tested against fifteen Gram-positive and sixteen Gram-negative strains. Out of the twenty-nine compounds, eighteen compounds 3-5, 7-9, 11-13, 15-25 showed a broad range of activity against tested Gram-positive microorganisms, whereas rest of the compounds 6, 10, 14 and 26-31 were found to be completely inactive against all the tested strains of Gram-positive bacteria. Five compounds 8, 11-13, and 15 showed activities against Gram-negative strains whereas the rest were devoid of any activity. Twenty-one (21) out of twenty-nine (29) compounds possessed antifungal activity. The structures of the synthetic compounds were confirmed by IR, EIMS and /sup 1/H-NMR spectral data. (author)

  17. Expeditious and Efficient Synthesis of Benzoxazoles, Benzothiazoles, Benzimidazoles Catalyzed by Ga(OTf)3 under Solvent-Free Conditions%Expeditious and Efficient Synthesis of Benzoxazoles, Benzothiazoles, Benzimidazoles Catalyzed by Ga(OTf)3 under Solvent-Free Conditions

    Institute of Scientific and Technical Information of China (English)

    刘巨艳; 刘倩; 徐玮; 王玮璐

    2011-01-01

    A new and efficient method for the synthesis of benzoxazoles, benzothiazoles, benzimidazoles from reactions of o-substituted aminoaromatics with orthoesters in the presence of catalytic amounts of Ga(OTf)3 under solvent-free conditions is presented. The remarkable features of this new protocol are high conversion, very short reaction times, cleaner reaction profiles under solvent-free conditions, straight forward procedure, and use of relatively non-toxic catalysts.

  18. Ligand-Free, Cu- and Fe-Catalyzed Selective Ring-Opening Arylations of Benzoxazoles with Aryl Iodides.

    Science.gov (United States)

    He, Yue; Mao, Jincheng; Rong, Guangwei; Yan, Hong; Zhang, Guoqi

    2016-06-01

    Cu- or Fe-based catalyst systems have been reported to selectively catalyze the N,N-diarylation or N-monoarylation of benzoxazoles ring-opening with aryl iodides in the absence of additional added ligand in polyethylene glycol under an inert atmosphere. Two types of coupling products (triphenylamines and diphenylamines) have been examined and the reaction routes can be simply controlled by changing the metal salts (Cu or Fe) as catalyst. A range of substrates have been investigated for the diverse reactions, and the corresponding arylation products were achieved in good to high yields. This selective, low-cost, and environmentally friendly protocol displays great potential for replacing existing methodologies as well as extending the synthetic applications of benzoxazoles. PMID:27037845

  19. Optical switching of 2-(2'-hydroxyphenyl) benzoxazole in different solvents

    Science.gov (United States)

    Zhang, G.; Wang, H.; Yu, Y.; Xiong, F.; Tang, G.; Chen, W.

    All-optical switching and beam deflection of 2-(2'-hydroxyphenyl) benzoxazole (HBO) in three species of solvent (cyclohexane, ethanol and dimethyl sulfoxide) have been investigated by using third-harmonic generation (355 nm) of a mode-locked Nd:YAG laser as a pump beam and a continuous-wave He-Ne laser (632.8 nm) as a probe beam. The nonlinear refractive indices of HBO in different solvents are determined by using the Z-scan technique. The optical switching and beam-deflection effects are due to the change of the refractive index of HBO under the pump beam. Through the study of the absorption spectra and the fluorescence spectra of HBO in different solvents, we conclude that the principal reason for the change of the refractive index of HBO is not the thermal effect because of absorption of the pump beam, but the excited-state intramolecular proton-transfer (ESIPT) effect of HBO under the pump beam. As the ESIPT process is very fast, HBO might be an excellent material for high-speed optical switching.

  20. A durable alternative for proton-exchange membranes: sulfonated poly(benzoxazole thioether sulfone)s

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dan [Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Lab of PEMFC Key Materials and Technologies, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Liaoning, Dalian 116023 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Li, Jinhuan [Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Song, Min-Kyu; Liu, Meilin [Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Yi, Baolian; Zhang, Huamin [Lab of PEMFC Key Materials and Technologies, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Liaoning, Dalian 116023 (China)

    2011-03-18

    To develop a durable proton-exchange membrane (PEM) for fuel-cell applications, a series of sulfonated poly(benzoxazole thioether sulfone)s (SPTESBOs) are designed and synthesized, with anticipated good dimensional stability (via acid-base cross linking), improved oxidative stability against free radicals (via incorporation of thioether groups), and enhanced inherent stability (via elimination of unstable end groups) of the backbone. The structures and the degree of sulfonation of the copolymers are characterized using Fourier-transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy ({sup 1}H NMR and {sup 19}F NMR). The electrochemical stabilities of the monomers are examined using cyclic voltammetry in a typical three-electrode cell configuration. The physicochemical properties of the membranes vital to fuel-cell performance are also carefully evaluated under conditions relevant to fuel-cell operation, including chemical and thermal stability, proton conductivity, solubility in different solvents, water uptake, and swelling ratio. The new membranes exhibit low dimensional change at 25 C to 90 C and excellent thermal stability up to 250 C. Upon elimination of unstable end groups, the co-polymers display enhanced chemical resistance and oxidative stability in Fenton's test. Further, the SPTESBO-HFB-60 (HFB-60=hexafluorobenzene, 60 mol% sulfone) membrane displays comparable fuel-cell performance to that of an NRE 212 membrane at 80 C under fully humidified condition, suggesting that the new membranes have the potential to be more durable but less expensive for fuel-cell applications. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. A Durable Alternative for Proton-Exchange Membranes: Sulfonated Poly(Benzoxazole Thioether Sulfone)s

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dan; Li, Jin Hui; Song, Min Kyu; Yi, Baolian; Zhang, Huamin; Liu, Meilin

    2011-02-24

    To develop a durable proton-exchange membrane (PEM) for fuel-cell applications, a series of sulfonated poly(benzoxazole thioether sulfone)s ( SPTESBOs) are designed and synthesized, with anticipated good dimensional stability (via acid–base cross linking), improved oxidative stability against free radicals (via incorporation of thioether groups), and enhanced inherent stability (via elimination of unstable end groups) of the backbone. The structures and the degree of sulfonation of the copolymers are characterized using Fourier-transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy ({sup 1}H NMR and {sup 19}F NMR). The electrochemical stabilities of the monomers are examined using cyclic voltammetry in a typical three-electrode cell configuration. The physicochemical properties of the membranes vital to fuel-cell performance are also carefully evaluated under conditions relevant to fuel-cell operation, including chemical and thermal stability, proton conductivity, solubility in different solvents, water uptake, and swelling ratio. The new membranes exhibit low dimensional change at 25°C to 90°C and excellent thermal stability up to 250°C. Upon elimination of unstable end groups, the co-polymers display enhanced chemical resistance and oxidative stability in Fenton's test. Further, the SPTESBO-HFB-60 (HFB-60=hexafluorobenzene, 60 mol% sulfone) membrane displays comparable fuel-cell performance to that of an NRE 212 membrane at 80°C under fully humidified condition, suggesting that the new membranes have the potential to be more durable but less expensive for fuel-cell applications.

  2. Synthesis, photophysical property study of novel fluorescent 4-(1,3-benzoxazol-2-yl)-2-phenylnaphtho[1,2-][1,3]oxazole derivatives and their antimicrobial activity

    Indian Academy of Sciences (India)

    Kiran R Phatangare; Bhushan N Borse; Vikas S Padalkar; Vikas S Patil; Vinod D Gupta; Prashant G Umape; N Sekar

    2013-01-01

    A series of 4-(1,3-benzoxazol-2-yl)-2-phenylnaphtho[1,2-][1,3]oxazole derivatives have been synthesized from intermediate 1-amino-3-(1,3-benzoxazol-2-yl)naphthalen-2-ol. This intermediate was obtained by coupling 3-(1,3-benzoxazol-2-yl)naphthalen-2-ol with 4-sulphobenzenediazonium chloride followed by reduction with sodium dithionate in water at pH 8-9. 3-(1,3-benzoxazol-2-yl)naphthalen-2-ol was synthesized from 3-hydroxynaphthalene-2-carboxylic acid and 2-amino phenol in the presence of PCl3 in chlorobenzene at 130-135°C. All these compounds were characterized by FT-IR, 1H NMR, mass spectral and elemental analysis. The synthesized compounds are fluorescent which absorbs in the range of 296 to 332 nm while emits in the ranges of 368 to 404 nm with excellent quantum yield. All compounds were evaluated for in vitro antibacterial activities against Escherichia coli and Staphylococcus aureus strains and in vitro antifungal activity against Candida albicans and Aspergillus niger strains by using serial dilution method.

  3. A comprehensive spectroscopic and computational investigation of intramolecular proton transfer in the excited states of 2-(2′-hydroxyphenyl) benzoxazole and its derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Padalkar, Vikas S. [Tinctorial Chemistry Group, Institute of Chemical Technology, Matunga, Mumbai 400019 (India); Ramasami, Ponnadurai, E-mail: ramchemi@intnet.mu [Computational Chemistry Group, Department of Chemistry, Faculty of Science, University of Mauritius, Réduit (Mauritius); Sekar, Nagaiyan, E-mail: n.sekar@ictmumbai.edu.in [Tinctorial Chemistry Group, Institute of Chemical Technology, Matunga, Mumbai 400019 (India)

    2014-02-15

    The excited-state intramolecular proton transfer (ESIPT) fluorescence of the 2-(2′ hydroxyphenyl) benzoxazole (HBO) and its derivatives with NO{sub 2} as electron acceptor and NH{sub 2} as electron donor at the 4 and 5 position of benzoxazole ring was studied by spectroscopic and computational methods. The changes in the electronic transition, energy levels, and orbital diagrams of the HBO derivatives were investigated using the DFT computations and they were correlated with the experimental spectral emission. The benzoxazole derivatives are fluorescent under UV-light in solution. Photophysical properties of the compounds were also studied in solvents of different polarities. Experimental absorption and emission wavelengths are in agreement with those computed with a deviation ranging between 0 and 50%. The computational methods have been useful for molecular understanding of the transitions responsible for the fluorescent spectra. -- Highlights: • Experimental photophysical properties of 2-substituted benzoxazoles in different solvents have been studied and compared with the computational data. • Compounds show dual emission due to ESIPT process and was supported by DFT and TD-DFT computations. • Experimental results and computational results are in good agreements.

  4. Excited state intramolecular proton transfer of 2-(2′,6′-dihydroxyphenyl)benzoxazole: Insights using computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Tathe, Abhinav B.; Gupta, Vinod D.; Shreykar, Milind R. [Tinctorial Chemistry Group, Department of Dyestuff Technology, Institute of Chemical Technology, N. P. Marg, Matunga, Mumbai, Maharashtra 400019 (India); Ramasami, Ponnadurai, E-mail: ramchemi@intnet.mu [Computational Chemistry Group, Department of Chemistry, Faculty of Science University of Mauritius, Réduit (Mauritius); Sekar, Nagaiyan, E-mail: n.sekar@ictmumbai.edu.in [Tinctorial Chemistry Group, Department of Dyestuff Technology, Institute of Chemical Technology, N. P. Marg, Matunga, Mumbai, Maharashtra 400019 (India)

    2014-10-15

    The photo-physical behaviour of 2-(2′,6′-dihydroxyphenyl) benzoxazole was studied using the Density Functional Theory (DFT), Time Dependent Density Functional Theory (TD-DFT) and Configuration Interaction Singles (CIS). Different functionals including the hybrid and M06X series were used to compute the absorption and emission. Experimental absorption and emission wavelengths are in good agreement with those predicted using TD-DFT [TD-B3LYP/6–31 G(d)]. The further improvement was not observed with the larger basis sets like 6–31 G(d,p) and 6–311 G(d,p). The rotational barrier was also calculated theoretically in chloroform (10.5–14.1 kcal/mol) and it was found to be close to the experimental energy value (10.5 kcal/mol). - Highlights: • Photo-physical data of 2-(2′,6′-dihydroxyphenyl)benzoxazole was studied theoretically. • The methods employed are DFT, TD-DFT and CIS. • The rotational barriers evaluated computationally. • The results of DFT and TD-DFT are in good agreement with the experiments. • This study can lead to a better understanding of ESIPT phenomenon computationally.

  5. Synthesis of 2-(1-Benzofuran-2-yl)-4-(1,3-benzoxazol-2-yl/ 1,3-benzothiazol-2-yl) Quinolines as Blue Green Fluorescent Probes

    OpenAIRE

    Bodke, Yadav D.; Sheelavanth Shankerrao; Hosanagara N. Harishkumar

    2013-01-01

    A series of novel 2-(1-benzofuran-2-yl)-4-(1,3 benzoxazol-2-yl/1,3-benzothiazol-2-yl) quinoline derivatives 4(a–d) were synthesized in one step by the reaction of 2-(1-benzofuran-2-yl) quinoline-4-carboxylic acids 3(a-b) with o-aminophenol and o-amino thiophenol, respectively, using polyphosphoric acid (PPA) as a cyclizing agent. The fluorescent properties of newly synthesized compounds were investigated in three different organic solvents like chloroform (CHCl3), tetrahydrofuran (THF), and d...

  6. Synthesis of luminescent ethynyl-extended regioisomers of borate complexes based on 2-(2'-hydroxyphenyl)benzoxazole.

    Science.gov (United States)

    Massue, Julien; Frath, Denis; Retailleau, Pascal; Ulrich, Gilles; Ziessel, Raymond

    2013-04-22

    A series of thirteen luminescent tetrahedral borate complexes based on the 2-(2'-hydroxyphenyl)benzoxazole (HBO) core is presented. Their synthesis includes the incorporation of an ethynyl fragment by Sonogashira cross-coupling reaction, with the goal of extending the conjugation and consequently redshifting their emission wavelength. Different regioisomers, substituted in the 3-, 4-, or 5-position of the phenolate side of the HBO core, were studied in order to compare their photophysical properties. The complexes were characterized by X-ray diffraction and NMR, UV/Vis, and emission spectroscopy in solution and in the solid state. In all cases, complexation to boron leads to a donor-acceptor character that impacts their photophysical properties. Complexes with a 3- or 5-substituted fragment display mild to pronounced internal charge transfer (ICT), a feature strengthened by the presence of p-dibutylaminophenylacetylene in the molecular structure, protonation of the nitrogen atom of which leads to a significant blueshift and an increase in quantum yield. On the contrary, when the ethynyl module is grafted on the 4-position, narrow, structured, symmetrical absorption/emission bands are observed. Moreover, the fact that protonation has little effect on the emission maximum wavelength reveals singlet excited-state decay. Solid-state emission properties reveal a redshift compared to solution, explained by tight packing of the π-conjugated systems and the high planarity of the dyes. Subsequent connection of these complexes to other photoactive subunits (BODIPY, Boranil) provides dyads in which efficient cascade energy transfer is observed. PMID:23447429

  7. The role of water in solvating the hydrogen-bonding center of 2-(2‧-hydroxyphenyl)benzoxazole

    Science.gov (United States)

    Abou-Zied, Osama K.

    2007-08-01

    2-(2'-Hydroxyphenyl)benzoxazole (HBO) has been useful as a probe to study tautomerization in DNA. In order to clarify the role of water in solvating the hydrogen-bonding center of HBO, we examine here the effect of water on the ground- and excited-state properties of HBO by steady state absorption and fluorescence spectroscopy, and by ab initio calculations. The study was carried out in solvents of varying polarity and hydrogen-bonding capability and in binary mixtures of 1,4-dioxane/water and methanol/water. HBO exists in three equilibrium structures in its ground state which are solvent-dependent, solvated and closed syn-enols and anti-enol. Only closed syn-enol is able to undergo tautomerization in the excited state to form syn-keto tautomer. Fluorescence due to solvated HBO was observed at 370 nm. The intensity change in the fluorescence peak at 370 nm as a function of water content in the binary solvents was quantitatively analyzed. Two water molecules were found to solvate the hydrogen-bonding center of the syn-enol tautomer in the ground state. The ground-state structures of the syn-enol tautomer with one to four water molecules were calculated by performing ab initio calculations at the MP2/6-31G(d) level and it was found that only two water molecules interact with the hydrogen-bonding center of HBO, confirming the above results. As water content increased in the binary mixtures, the keto tautomer fluorescence shifted to the blue and increased in intensity. This change was attributed to the formation of an anion species in the excited state which is stabilized in high polar binary mixtures. This result was confirmed by measuring the fluorescence in aqueous solution of pH 13. At high water contents, the behavior of the binary mixtures approaches that of pure water in which HBO undergoes water-assisted tautomerization to give the syn-keto tautomer.

  8. Environment-sensitive benzoxazole based fluorescein derivatives: Synthesis and application to the design of ON–OFF fluorescent chemosensors for microenvironment

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Vikas; Padalkar, Vikas; Sekar, Nagaiyan, E-mail: nethi.sekar@gmail.com

    2015-02-15

    The intermediate 2-(2′, 4,-dihydroxyphenyl) benzoxazole was used for the synthesis of substituted fluorescein derivatives. Fluorescence behavior of the synthesized fluorescein derivatives was studied under different microenvironments like pH, viscosity, surfactant sodium dodecyl sulfate (SDS) and protein Bovine Serum Albumin (BSA). Further, the fluorescence of these molecules was used for the detection of blood sample. Photophysical properties show that all the fluorescent compounds are very sensitive to pH, and in basic medium these compounds show hyper chromic shift. These compounds are also sensitive to the viscosity of the medium. All the compounds are characterized by FT-IR, H NMR and mass spectral analysis. - Highlights: • Synthesized novel ESIPT inspired compounds which are unknown to this date, synthesis route is very easy. • Existing fluorescein compounds show single absorption in UV region having restricted applications are overcome by introducing ESIPT unit in fluorescein core. • First and unique study of fluorescein compounds having pH sensitive dual absorption–emission characteristics. • Relative fluorescence quantum yield of fluorescein derivatives was investigated.

  9. Synthesis of 2-(1-Benzofuran-2-yl-4-(1,3-benzoxazol-2-yl/ 1,3-benzothiazol-2-yl Quinolines as Blue Green Fluorescent Probes

    Directory of Open Access Journals (Sweden)

    Yadav D. Bodke

    2013-01-01

    Full Text Available A series of novel 2-(1-benzofuran-2-yl-4-(1,3 benzoxazol-2-yl/1,3-benzothiazol-2-yl quinoline derivatives 4(a–d were synthesized in one step by the reaction of 2-(1-benzofuran-2-yl quinoline-4-carboxylic acids 3(a-b with o-aminophenol and o-amino thiophenol, respectively, using polyphosphoric acid (PPA as a cyclizing agent. The fluorescent properties of newly synthesized compounds were investigated in three different organic solvents like chloroform (CHCl3, tetrahydrofuran (THF, and dimethyl sulfoxide (DMSO. The photophysical constants such as quantum yield and stokes shift were determined. From the results of fluorescence study, it is evident that all synthesized compounds are fluorescent in solution. Compound 4a emitted green light (490.4 nm, 518.2 nm, and 522.4 nm with high quantum yield in all the three solvents, while compounds 4b, 4c, and 4d emitted green light (512 nm, 499 nm, 510 nm only in polar solvent DMSO. All fluorescent probes exhibited a bathochromic shift on increase in polarity of the solvent.

  10. Moderate modulation of disease in the G93A model of ALS by the compound 2-(2-hydroxyphenyl)-benzoxazole (HBX).

    Science.gov (United States)

    Evans, Teresa M; Bhattacharya, Arunabh; Shi, Yun; Qi, Wenbo; Block, Travis J; Chaudhuri, Asish; Chaudhuri, Alakananda Ray; Hawker, Kara; Van Remmen, Holly

    2016-06-15

    Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurological disease characterized by degeneration and death of motor neurons. Aberrant protein aggregation and oxidative stress are implicated in the etiology of ALS; thus preventing propagation of early aggregation events and oxidative damage could be an effective therapy. We tested the effect of dietary supplementation (initiated 40 days of age) with 2-(2-hydroxyphenyl)-benzoxazole (HBX), a compound with metal chelator and anti-aggregation properties, on disease onset, progression and lifespan in the G93A mouse model of ALS. Tests were not sufficiently powerful to detect any change to survival distribution of mice treated with HBX. However, the disease onset was delayed and max lifespan was increased in the treatment group. Additionally, disease progression was moderated as shown by reduced neuromuscular denervation measured by repetitive nerve stimulation. F2-isoprostanes, a marker of oxidative damage, are elevated in skeletal muscle from G93A mice at onset and this increase is prevented in HBX fed G93A mice. Furthermore, HBX treatment reduced mutant SOD1 protein aggregation in whole spinal cord of G93A mice at disease onset. Overall, our data suggests that HBX may be able to improve the degenerative symptoms of ALS through the prevention of oxidative damage and protein aggregation. Further studies are needed to uncover the mechanistic effects of HBX in ameliorating ALS pathology. PMID:27138280

  11. Environment-sensitive benzoxazole based fluorescein derivatives: Synthesis and application to the design of ON–OFF fluorescent chemosensors for microenvironment

    International Nuclear Information System (INIS)

    The intermediate 2-(2′, 4,-dihydroxyphenyl) benzoxazole was used for the synthesis of substituted fluorescein derivatives. Fluorescence behavior of the synthesized fluorescein derivatives was studied under different microenvironments like pH, viscosity, surfactant sodium dodecyl sulfate (SDS) and protein Bovine Serum Albumin (BSA). Further, the fluorescence of these molecules was used for the detection of blood sample. Photophysical properties show that all the fluorescent compounds are very sensitive to pH, and in basic medium these compounds show hyper chromic shift. These compounds are also sensitive to the viscosity of the medium. All the compounds are characterized by FT-IR, H NMR and mass spectral analysis. - Highlights: • Synthesized novel ESIPT inspired compounds which are unknown to this date, synthesis route is very easy. • Existing fluorescein compounds show single absorption in UV region having restricted applications are overcome by introducing ESIPT unit in fluorescein core. • First and unique study of fluorescein compounds having pH sensitive dual absorption–emission characteristics. • Relative fluorescence quantum yield of fluorescein derivatives was investigated

  12. Paliperidone: 3-{2-[4-(6-fluoro-1,2-benzoxazol-3-ylpiperidin-1-yl]ethyl}-9-hydroxy-2-methyl-1,6,7,8,9,9a-hexahydropyrido[1,2-a]pyrimidin-4-one

    Directory of Open Access Journals (Sweden)

    Richard Betz

    2011-11-01

    Full Text Available The title compound (also known as 9-hydroxyrisperidone, C23H27FN4O3, is a heterocyclic compound with manifold pharmacological properties. The hydroxy group shows disorder over two positions, with site-occupancy factors of 0.856 (2 and 0.144 (2. The piperidine ring adopts a chair conformation, while the annulated ring bearing the hydroxy group is present in a half-chair conformation. Classical O—H...O hydrogen bonds as well as C—H...N contacts connect the molecules into undulating sheets lying perpendicular to the crystallographic b axis. The shortest centroid–centroid distance between two centers of gravity is 3.5867 (8 Å and is apparent between the benzoxazole moiety and the six-membered ring bearing the keto substituent.

  13. Electronic and photophysical properties of 2-(2′-hydroxyphenyl)benzoxazole and its derivatives enhancing in the excited-state intramolecular proton transfer processes: A TD-DFT study on substitution effect

    International Nuclear Information System (INIS)

    The effect of electron donating and withdrawing substituents on the enol absorption and keto emission spectra of 2-(2′-hydroxyphenyl)benzoxazole (HBO) and its derivatives has been systematically investigated by means of density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The enol absorption spectra of HBO were simulated by using five different DFTs with various exchange-correlation functions to validate a suitable functional prior to being further used as a method of choice to study the effect of substituents on the spectral characteristics of HBO derivatives. The popular B3LYP (Becke, three-parameter, Lee–Yang–Parr) exchange-correlation functional is found to provide the best desirable result in predicting the absorption spectrum close to experimental data. In the ground state, enol forms of HBO and its derivatives are more stable than those of keto forms, while in the first lowest excited state, keto forms are found to be more stable than their enol forms. Overall, simulated absorption and emission spectra of HBO and its derivatives from TD-B3LYP calculations are in good agreement with the experimental data. For enol, absorption maxima of HBO derivatives having electron-withdrawing groups are red-shift corresponding to their lower HOMO–LUMO energy gaps compared to that of HBO. For keto emission, HBO having electron donating groups (m-MeHBO and MHBO) and withdrawing group (CNHBO) at 4′-position on the phenol fragment as well as electron donating groups (HBOMe and HBOM) at 6-position on the benzoxazole fragment make the position of keto emission peak shift to shorter wavelength (blue-shift). However, HBO derivatives with electron withdrawing groups (HBOF, HBOCl, HBOA and HBOE) at 6-position give redshifted emission compared to the parent compound (HBO). The type of substituent on both 4′- and 6-positions certainly has a pronounced effect on the absorption and emission spectra of HBO derivatives. - Highlights: • Simulated spectra

  14. Electronic and photophysical properties of 2-(2′-hydroxyphenyl)benzoxazole and its derivatives enhancing in the excited-state intramolecular proton transfer processes: A TD-DFT study on substitution effect

    Energy Technology Data Exchange (ETDEWEB)

    Daengngern, Rathawat; Kungwan, Nawee, E-mail: naweekung@gmail.com

    2015-11-15

    The effect of electron donating and withdrawing substituents on the enol absorption and keto emission spectra of 2-(2′-hydroxyphenyl)benzoxazole (HBO) and its derivatives has been systematically investigated by means of density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The enol absorption spectra of HBO were simulated by using five different DFTs with various exchange-correlation functions to validate a suitable functional prior to being further used as a method of choice to study the effect of substituents on the spectral characteristics of HBO derivatives. The popular B3LYP (Becke, three-parameter, Lee–Yang–Parr) exchange-correlation functional is found to provide the best desirable result in predicting the absorption spectrum close to experimental data. In the ground state, enol forms of HBO and its derivatives are more stable than those of keto forms, while in the first lowest excited state, keto forms are found to be more stable than their enol forms. Overall, simulated absorption and emission spectra of HBO and its derivatives from TD-B3LYP calculations are in good agreement with the experimental data. For enol, absorption maxima of HBO derivatives having electron-withdrawing groups are red-shift corresponding to their lower HOMO–LUMO energy gaps compared to that of HBO. For keto emission, HBO having electron donating groups (m-MeHBO and MHBO) and withdrawing group (CNHBO) at 4′-position on the phenol fragment as well as electron donating groups (HBOMe and HBOM) at 6-position on the benzoxazole fragment make the position of keto emission peak shift to shorter wavelength (blue-shift). However, HBO derivatives with electron withdrawing groups (HBOF, HBOCl, HBOA and HBOE) at 6-position give redshifted emission compared to the parent compound (HBO). The type of substituent on both 4′- and 6-positions certainly has a pronounced effect on the absorption and emission spectra of HBO derivatives. - Highlights: • Simulated spectra

  15. Paliperidone: 3-{2-[4-(6-fluoro-1,2-benzoxazol-3-yl)piperidin-1-yl]eth­yl}-9-hy­droxy-2-methyl-1,6,7,8,9,9a-hexa­hydro­pyrido[1,2-a]pyrimidin-4-one

    Science.gov (United States)

    Betz, Richard; Gerber, Thomas; Hosten, Eric; Dayananda, Alaloor S.; Yathirajan, Hemmige S.; Thomas, Saji

    2011-01-01

    The title compound (also known as 9-hy­droxy­risperidone), C23H27FN4O3, is a heterocyclic compound with manifold pharmacological properties. The hy­droxy group shows disorder over two positions, with site-occupancy factors of 0.856 (2) and 0.144 (2). The piperidine ring adopts a chair conformation, while the annulated ring bearing the hy­droxy group is present in a half-chair conformation. Classical O—H⋯O hydrogen bonds as well as C—H⋯N contacts connect the mol­ecules into undulating sheets lying perpendicular to the crystallographic b axis. The shortest centroid–centroid distance between two centers of gravity is 3.5867 (8) Å and is apparent between the benzoxazole moiety and the six-membered ring bearing the keto substituent. PMID:22219974

  16. Aromatic Polyimide and Crosslinked Thermally Rearranged Poly(benzoxazole-co-imide) Membranes for Isopropanol Dehydration via Pervaporation

    KAUST Repository

    Ming Xu, Yi

    2015-10-31

    Novel crosslinked thermally rearranged polybenzoxazole (C-TR-PBO) membranes, which show impressive results for isopropanol dehydration, have been obtained via in-situ thermal conversion of hydroxyl-containing polyimide precursors. The polyimide precursors are synthesized by the polycondensation of three monomers; namely, 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,3′-dihydroxybenzidine diamine (HAB) and 3,5-diaminobenzoic acid (DABA). Due to the incorporation of the carboxylic-group containing diamine DABA into an ortho-hydroxypolyimide precursor, the thermal induced crosslinking reaction can be achieved together with the thermal rearrangement process. Consequently, a synergistic effect of high permeability and high selectivity can be realized in one step. The resultant C-TR-PBO membrane exhibits an unambiguous enhancement in permeation flux compared to their polyimide precursors. Moreover, the newly developed C-TR-PBO membrane displays stable isopropanol dehydration performance at 60 °C throughout the continuous 200 hours. The promising preliminary results achieved in this study may offer useful insights for the selection of membrane materials for pervaporation and new methods to molecularly design next-generation pervaporation membranes.

  17. Femtosecond fluorescence upconversion studies of excited-state proton-transfer dynamics in 2-(2 '-hydroxyphenyl)benzoxazole (HBO) in liquid solution and DNA

    Science.gov (United States)

    Wang, H.; Zhang, H.; Abou-Zied, O. K.; Yu, C.; Romesberg, F. E.; Glasbeek, M.

    2003-01-01

    A femtosecond fluorescence upconversion study is reported for HBO in solution, as well as for HBO incorporated in DNA. The typical time for the excited-state intramolecular proton-transfer reaction of the syn-enol tautomer in solution and in DNA has been determined to be 150 fs. In addition, the lifetimes of the keto, the anti-enol and the 'solvated enol' tautomer forms were determined in protic solvents, aprotic solvents and DNA. Picosecond rise and decay components in the fluorescence transients with characteristic times between 3 and 25 ps are also observed and attributed to the effects of vibrational cooling.

  18. 3-{[5-(4-Bromophenylimidazo[2,1-b][1,3,4]thiadiazol-2-yl]methyl}-1,2-benzoxazole

    Directory of Open Access Journals (Sweden)

    Ravi S. Lamani

    2011-01-01

    Full Text Available In the title compound, C18H11BrN4OS, the imidazothiadiazole and benzisoxazole rings are individually planar with maximum deviations of 0.025 (3 0.015 (4 Å, respectively, and are inclined at an angle of 23.51 (7° with respect to each other. The planes of the imidazothiadiazole and bromophenyl rings are inclined at an angle of 27.34 (3°. In the crystal, intermolecular C—H...N interactions result in chains of molecules along the b and c axes. Moreover, C—H...O interactions result in centrosymmetric head-to-head dimers with R22(24 graph-set motifs. The molecular packing is further stabilized by π–π stacking interactions between the imidazole rings with a shortest centroid–centroid distance of 3.492 (3 Å. In addition, C—H...π interactions are observed in the crystal structure.

  19. 含噁唑结构固化剂的分子动力学模拟研究%Study on Curing Agent Containing Benzoxazole Groups by Using Molecular Simulation Technology

    Institute of Scientific and Technical Information of China (English)

    卢晓东; 贾近; 肖海英; 黄玉东; 张红星

    2011-01-01

    The models of diglycidyl ether of bisphenol A/diaminophenylbenzoxazoie (E/ABO) were established by means of molecular simulation technique. The study on the glass transition temperature of the cured epoxy resin was performed by means of the models with computer and the simulations were verifying in the experiments. The results showed that the glass transition temperature of cured epoxy resin system could be predicted by means of molecular simulation technique and the glass transition temperatures of the developed E/ABO system were 217t (determined by DSC) and 1881C (determined by DMA). Compared to E/DDS system, it was a great improvement.%首先利用分子模拟技术建立了缩水甘油醚双酚A环氧树脂/二胺基苯并噁唑(E/ABO)固化环氧树脂体系的简单分子模型,并利用这些模型在计算机上对树脂体系的玻璃化转变温度进行研究,同时利用实验进行验证.结果表明,利用分子模拟技术可以很好地预测环氧树脂固化体系的玻璃化转变温度;同时新开发的E/ABO环氧树脂固化体系的玻璃化转变温度分别为217℃(DSC法)和188℃(DMA法),与环氧树脂/二胺基二苯基砜(E/DDS)固化体系相比有很大的提高.

  20. Synthesis of Some New 2-(3-Aryl-1-phenyl-4-pyrazolyl-benzoxazoles Using Hypervalent Iodine Mediated Oxidative Cyclization of Schiff’s Bases

    Directory of Open Access Journals (Sweden)

    Ajay Kumar

    2006-01-01

    Full Text Available Ten new 2-(3-aryl-1-phenyl-4-pyrazolylbenzoxazoles have been synthesized by oxidative intramolecular cyclization of the corresponding Schiff’s bases using iodobenzene diacetate in methanol as an oxidant.

  1. Pharmacophore combination as a useful strategy to discover new antitubercular agents

    Czech Academy of Sciences Publication Activity Database

    Rana, D. N.; Chhabria, M. T.; Shah, N. K.; Brahmkshatriya, Pathik

    2014-01-01

    Roč. 23, č. 1 (2014), s. 370-381. ISSN 1054-2523 Institutional support: RVO:61388963 Keywords : antitubercular * benzoxazole * interaction energy * molecular docking * pharmacophore * pyrazoline Subject RIV: CC - Organic Chemistry Impact factor: 1.402, year: 2014

  2. C-H arylation of azaheterocycles: a direct ligand-free and Cu-catalyzed approach using diaryliodonium salts.

    Science.gov (United States)

    Kumar, Dalip; Pilania, Meenakshi; Arun, V; Pooniya, Savita

    2014-09-01

    An efficient and high yielding Cu-catalyzed direct C-H arylation of azaheterocycles including oxadiazoles, thiadiazoles, benzoxazoles and benzothiazoles has been achieved by employing easily accessible diaryliodonium salts. PMID:25017573

  3. Spacecraft Thermal Protection Systems (TPS) Based on Polybenzoxazole (PBO) With Unique UV, Atomic-O and Solar Wind Protective Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Poly(benzoxazole) (PBO) is a new polymeric material extremely promising for external spacecraft structural applications, including, e.g., debris and micrometeoroid...

  4. Fluorescent compounds for plastic scintillation applications

    International Nuclear Information System (INIS)

    Several 2-(2'-hydroxyphenyl)benzothiazole, -benzoxazole, and -benzimidazole derivatives have been prepared. Transmittance, fluorescence, light yield, and decay time characteristics of these compounds have been studied in a polystyrene matrix and evaluated for use in plastic scintillation detectors. Radiation damage studies utilizing a 60C source have also been performed

  5. Synthesis and Spectroscopic Characterisation of N-Alkyl Quaternary Ammonium Salts Typical Precursors of Cyanines

    Directory of Open Access Journals (Sweden)

    P. Almeida

    2002-03-01

    Full Text Available The synthesis and spectroscopic characterisation of some representative N-alkylsubstituted quaternary ammonium salts derived from benzothiazole, benzoxazole, benzoselenazole, indole and quinoline are described. These heterocyclic salts, bearing an activated methyl group in the 2-position in relation to the nitrogen atom and N-methyl, -pentyl, -hexyl and -decyl chains, are typical precursors of cyanine dyes.

  6. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    Science.gov (United States)

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities. PMID:19899783

  7. Design, synthesis and antitumor activity of 3-substituted quinolone derivatives (Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A series of quinolone derivatives containing benzimidazole, benzoxazole or benzothiazole ring were synthesized. The cytotoxicity of 12 new compounds was evaluated in KB, Be17402, A2780 and HT-29 cell lines. Most of synthesized compounds showed moderate inhibitory activity against cancer cells. The inhibitory activities of 6k, against KB and A2780 tumor cells are comparable to that of topotecan, one of topoisomerase I inhibitors.

  8. Oxidative cyclization of a phenolic Schiff base and synthesis of a cyclometalated ruthenium nitrosyl complex: photoinduced NO release by visible light.

    Science.gov (United States)

    Ghosh, Kaushik; Kumar, Sushil; Kumar, Rajan; Singh, Udai P; Goel, Nidhi

    2010-08-16

    The reactivity of sigma-arylruthenium cyclometallate [Ru(L(SB1))(PPh(3))(2)Cl] [1; L(SB1)H(2) = 4-methyl-2-(4-nitrobenzylideneamino)phenol] with nitric oxide (NO) gave rise to nitrosylation at the metal center, ring nitration, and oxidative cyclization, affording benzoxazole derivative formation. The molecular structure of the resultant nitrosyl complex, [Ru(L(PB1))(PPh(3))(2)(NO)Cl](ClO(4)) [2; L(PB1)H = 5-methyl-7-nitro-2-(4-nitrophenyl)benzoxazole] was determined, and a different sigma-arylruthenium cyclometallate was characterized in which the benzoxazole derivative was found to be coordinated to the metal center. The crystal structure and IR and NMR spectral data confirmed the formation of a diamagnetic {RuNO}(6) species with a S = 0 ground state and a {Ru(II)NO(+)}(6) description of the {RuNO}(6) moiety. Coordinated NO in the resultant complex 2 was photolabile under visible light and was transferred to reduced myoglobin. PMID:20690733

  9. Small diameter scintillator made optical fiber and detector using such fibers. Fibres optiques scintillantes de faible diametre et detecteur comportant de telles fibres

    Energy Technology Data Exchange (ETDEWEB)

    Bourdinaud, M.; Le Bras, J.Y.; Thevenin, J.C.; Rebourgeard, P.

    1990-03-30

    A patent is claimed for the invention of optical fibers and a detector using such fibers. The invention is to be applied to the detection of particles and ionizing radiations. The small diameter fibers are formed by a sheathed core. The core consists of (biphenylyl-4) - phenil-6 benzoxazol dissolved in polystirene or polyvinyltoluene. The material of the envelope is the polymetacrylate of methyl. The design of the detector, the characteristics and the fabrication of the fibers and the system's operation are presented.

  10. Studies of 3-amino-4-hydroxyl benzoic acid phosphate

    International Nuclear Information System (INIS)

    3-amino-4-hydroxyl benzoic acid phosphate was synthesized from 4-chloro benzoic acid through three steps, the whole process was cost-effective in which the materials in each step were reused. More importantly, phosphoric acid medium did no harm to Pd-C catalyst in the hydrogenation and the Pd-C catalyst could be recycled for ten times at least without decrease in catalytic activity. In addition, product could meet the requirement of polymerization reaction of producing poly(2,5-benzoxazole) without dehydrochlorogenation. In this process, good conversion, high overall yield (79.28%) and high purity (99.30% by HPLC) were achieved. (author)

  11. Synthesis and Optical Characterization of Mixed Ligands Beryllium Complexes for Display Device Applications

    OpenAIRE

    Vandna Nishal; Devender Singh; Raman Kumar Saini; Vijeta Tanwar; Shri Bhagwan; Sonika Kadyan; Ishwar Singh; Pratap Singh Kadyan

    2015-01-01

    Synthesis and photoluminescent behaviour of mixed ligand based beryllium complexes with 2-(2-hydroxyphenyl)benzoxazole (HPB) and 5-chloro-8-hydroxyquinoline (Clq) or 5,7-dichloro-8-hydroxyquinoline (Cl2q) or 2-methyl-8-hydroxyquinoline (Meq) or 8-hydroxyquinoline (q) are reported in this work. These complexes, that is, [BeHPB(Clq)], [BeHPB(Cl2q)], [BeHPB(Meq)], and [BeHPB(q)], were prepared and their structures were confirmed by elemental analysis, Fourier transform infrared spectroscopy, nuc...

  12. Air-Stable Triazine-Based Ni(II) PNP Pincer Complexes As Catalysts for the Suzuki-Miyaura Cross-Coupling.

    Science.gov (United States)

    Mastalir, Matthias; Stöger, Berthold; Pittenauer, Ernst; Allmaier, Günter; Kirchner, Karl

    2016-07-01

    Air-stable, thermally robust, and well-defined cationic Ni(II) PNP pincer complexes based on the 2,4-diaminotriazine scaffold are described. These complexes are active catalysts for the Suzuki-Miyaura cross-coupling of a wide range of aryl, heteroaryl (including benzoxazole, thiazole, pyridine, pyrimidine, thiazole), primary and secondary alkyl halides, and pseudohalides with different organoboronate reagents giving excellent to good isolated yields. Neutral deprotonated complexes seem to play a key role in the catalytic process. PMID:27281438

  13. PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix

    CERN Document Server

    Wieczorek, A; Jasińska, B; Gorgol, M; Bednarski, T; Białas, P; Czerwiński, E; Gajos, A; Kamińska, D; Kapłon, Ł; Kochanowski, A; Korcyl, G; Kowalski, P; Kozik, T; Krzemień, W; Kubicz, E; Niedźwiecki, S; Pałka, M; Raczyński, L; Rudy, Z; Rundel, O; Sharma, N G; Silarski, M; Słomski, A; Strzelecki, A; Wiślicki, W; Zieliński, M; Moskal, P

    2015-01-01

    The polystyrene dopped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter, prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260 K, 283 K and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.

  14. Novel arylsulfonamide derivatives with 5-HT₆/5-HT₇ receptor antagonism targeting behavioral and psychological symptoms of dementia.

    Science.gov (United States)

    Kołaczkowski, Marcin; Marcinkowska, Monika; Bucki, Adam; Pawłowski, Maciej; Mitka, Katarzyna; Jaśkowska, Jolanta; Kowalski, Piotr; Kazek, Grzegorz; Siwek, Agata; Wasik, Anna; Wesołowska, Anna; Mierzejewski, Paweł; Bienkowski, Przemyslaw

    2014-06-12

    In order to target behavioral and psychological symptoms of dementia (BPSD), we used molecular modeling-assisted design to obtain novel multifunctional arylsulfonamide derivatives that potently antagonize 5-HT(6/7/2A) and D2 receptors, without interacting with M1 receptors and hERG channels. In vitro studies confirmed their antagonism of 5-HT(7/2A) and D2 receptors and weak interactions with key antitargets (M1R and hERG) associated with side effects. Marked 5-HT6 receptor affinities were also observed, notably for 6-fluoro-3-(piperidin-4-yl)-1,2-benzoxazole derivatives connected by a 3-4 unit alkyl linker with mono- or bicyclic, lipophilic arylsulfonamide moieties. N-[4-[4-(6-Fluoro-1,2-benzoxazol-3-yl)piperidin-1-yl]butyl]benzothiophene-2-sulfonamide (72) was characterized in vitro on 14 targets and antitargets. It displayed dual blockade of 5-HT6 and D2 receptors and negligible interactions at hERG and M1 receptors. Unlike reference antipsychotics, 72 displayed marked antipsychotic and antidepressant activity in rats after oral administration, in the absence of cognitive or motor impairment. This profile is particularly attractive when targeting a fragile, elderly BPSD patient population. PMID:24805037

  15. BOXTO as a real-time thermal cycling reporter dye

    Indian Academy of Sciences (India)

    Ashraf I Ahmad

    2007-03-01

    The unsymmetrical cyanine dyes BOXTO (4-[6-(benzoxazole-2-yl-(3-methyl-)-2,3-dihydro-(benzo-1,3-thiazole)-2-methylidene)]-1-methyl-quinolinium chloride) and its positive divalent derivative BOXTO-PRO (4-[(3-methyl-6-(benzoxazole-2-yl)-2,3-dihydro-(benzo-1,3-thiazole)-2-methylidene)]-1-(3-trimethylammonium-propyl)-quinolinium dibromide) were studied as real-time PCR reporting fluorescent dyes and compared to SYBR GREEN I (SG) (2-[N-(3-dimethylaminopropyl)-N-propylamino]-4-[2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene]-1-phenyl-quinolinium). Unmodified BOXTO showed no inhibitory effects on real-time PCR, while BOXTO-PRO showed complete inhibition. Sufficient fluorescent signal was acquired when 0.5–1.0 M BOXTO was used with RotorGene and iCycler platforms. Statistical analysis showed that there is no significant difference between the efficiency and dynamic range of BOXTO and SG. BOXTO stock solution (1.5 mM) was stable at –20°C for more than one year and 40 M BOXTO solution was more stable than 5x SG when both were stored at 4°C for 45 days.

  16. An efficient ratiometric fluorescent probe for tracking dynamic changes in lysosomal pH.

    Science.gov (United States)

    Wang, Qianqian; Zhou, Liyi; Qiu, Liping; Lu, Danqing; Wu, Yongxiang; Zhang, Xiao-Bing

    2015-08-21

    Lysosomes are acidic organelles (approximately pH 4.5-5.5) and tracking the changes in lysosomal pH is of great biological importance. To address this issue, quite a few of fluorescent probes have been developed. However, few of these probes can realize the tracking of dynamic changes in lysosomal pH. Herein, we report a new lysosome-targeted ratiometric fluorescent probe (FR-Lys) by hybridizing morpholine with a xanthane derivative and an o-hydroxy benzoxazole group. In this probe, the morpholine group serves as a targeting unit for lysosome, the xanthane derivative exhibits a pH-modulated open/close reaction of the spirocycle, while the o-hydroxy benzoxazole moiety shows a pH modulated excited-state intramolecular proton transfer (ESIPT) process. Such a design affords the probe a ratiometric fluorescence response towards pH with pH values ranging from 4.0 to 6.3. The response of the probe to pH was fast and reversible with high selectivity. Moreover, this probe possesses further advantages such as easy synthesis, high photostability and low cytotoxicity. These features are favorable for tracking dynamic pH changes in biosystems. It was then applied for dynamic imaging pH changes in lysosomes with satisfactory results. PMID:26107774

  17. Preclinical studies of potential amyloid binding PET/SPECT ligands in Alzheimer's disease

    International Nuclear Information System (INIS)

    Visualizing the neuropathological hallmarks amyloid plaques and neurofibrillary tangles of Alzheimer's disease in vivo using positron emission tomography (PET) or single photon emission computed tomography will be of great value in diagnosing the individual patient and will also help in our understanding of the disease. The successful introduction of [11C]PIB as a PET tracer for the amyloid plaques less than 10 years ago started an intensive research, and numerous new compounds for use in molecular imaging of the amyloid plaques have been developed. The candidates are based on dyes like thioflavin T, Congo red and chrysamine G, but also on other types such as benzoxazoles, curcumin and stilbenes. In the present review, we present methods of the radiochemistry and preclinical evaluation as well as the main properties of some of these compounds.

  18. XPS study of PBO fiber surface modified by incorporation of hydroxyl polar groups in main chains

    International Nuclear Information System (INIS)

    Dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO), a modified poly(p-phenylene benzoxazole) (PBO) polymer containing double hydroxyl groups in polymer chains, was synthesized by copolymerization of 4,6-diamino resorcinol dihydrochloride (DAR), purified terephthalic acid (TA) and 2,5-dihydroxyterephthalic acid (DHTA). DHPBO fibers were prepared by dry-jet wet-spinning method. The effects of hydroxyl polar groups on the surface elemental compositions of PBO fiber were investigated by X-ray photoelectron spectroscopy (XPS). The results show that the ratio of oxygen/carbon on the surface of DHPBO fibers is higher than that on the surface of PBO fibers, which indicates the content of polar groups on the surface of DHPBO fiber increase compared with PBO fiber.

  19. Receptor-Guided De Novo Design of Dengue Envelope Protein Inhibitors.

    Science.gov (United States)

    Desai, Vishal H; Kumar, Sivakumar Prasanth; Pandya, Himanshu A; Solanki, Hitesh A

    2015-10-01

    Inhibitor design associated with the dynamics of dengue envelope protein at pre-fusion stage is a prominent strategy to interfere fusion transition of dengue virus with the host cell membrane. Receptor-guided de novo inhibitors were designed based on the knowledge of co-crystallized detergent, β-octyl glucoside. Pharmacophore features distribution showed the preference of aromatic groups with H bonding features connected to aliphatic bulky group as the skeleton for inhibitor design. Molecular dynamic simulations revealed (2R)-2-[(6-amino-1-oxohexan-2-yl)amino]-4-[6-(4-phenylpiperidine-1-yl)-1,2-benzoxazol-3-yl]butanoate as the probable binder which developed extensive conservative interactions despite the local pocket residues movements especially from kl β-hairpin, the key structural unit for initiating conformational changes required for fusion transition. The electronic and hydrophobic potentials also indicated that butanoate molecule as the initial lead for envelope protein inhibitors. PMID:26299376

  20. Fluorescent Brighteners as Visible LED-Light Sensitive Photoinitiators for Free Radical Photopolymerizations.

    Science.gov (United States)

    Zuo, Xiaoling; Morlet-Savary, Fabrice; Graff, Bernadette; Blanchard, Nicolas; Goddard, Jean-Philippe; Lalevée, Jacques

    2016-05-01

    The photochemical and electrochemical investigations of commercially available, safe, and cheap fluorescent brighteners, namely, triazinylstilbene (commercial name: fluorescent brightener 28) and 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene, as well as their original use as photoinitiators of polymerization upon light emitting diode (LED) irradiation are reported. Remarkably, their excellent near-UV-visible absorption properties combined with outstanding fluorescent properties allow them to act as high-performance photoinitiators when used in combination with diaryliodonium salt. These two-component photoinitiating systems can be employed for free radical polymerizations of acrylate. In addition, this brightener-initiated photopolymerization is able to overcome oxygen inhibition even upon irradiation with low LED light intensity. The underlying photochemical mechanisms are investigated by electron-spin resonance-spin trapping, fluorescence, cyclic voltammetry, and steady-state photolysis techniques. PMID:27072016

  1. Paliperidonium nitrate

    Directory of Open Access Journals (Sweden)

    Jingshui Ge

    2012-10-01

    Full Text Available In the title molecular salt (systematic name: 3-{2-[4-(6-fluoro-1,2-benzoxazol-3-ylpiperidin-1-yl]ethyl}-9-hydroxy-2-methyl-1,6,7,8,9,9a-hexahydropyrido[1,2-a]pyrimidin-4-one nitrate, C23H29FN4O3+·NO3−, the piperidine ring displays a chair conformation and its N atom is protonated; the N—H bond is in an axial orientation. The ring bearing the hydroxy group exhibits a half-chair conformation. The hydroxy group as well as the adjacent methylene group are disordered over two sets of sites in a 0.823 (5:0.177 (5 ratio. In the crystal, O—H...N, O—H...O, N—H...O and N—H...N hydrogen bonds connect the components into a three-dimensional network.

  2. New heterocycles having double characters; as antimicrobial and surface active agents.

    Directory of Open Access Journals (Sweden)

    El-Sayed, R.

    2004-12-01

    Full Text Available Fatty acids isothiocyanate (1 was used as a starting material to synthesize some important heterocycles such as triazoles, oxazoles, thiazoles, benzoxazoles and quinazolines by treating with different types of nucleophiles such as nitrogen nucleophiles, oxygen nucleophiles, and sulfur nucleophiles. The produced compounds were subjected to propylene oxide in different moles (n = 3, 5 and 7 to produce novel groups of nonionic compounds having the double function as antimicrobial and surface active agents which can be used in the manufacturing of drugs, cosmetics, pesticides or can be used as antibacterial and/or antifungal. The physical properties as surface and interfacial tension, cloud point, foaming height, wetting time, emulsification power and the critical micelle concentration (CMC were determined, antimicrobial and biodegradability were also determined.Isocianatos de acidos grasos se utilizaron como material de partida para la síntesis de importantes heterociclos tales como triazoles, oxazoles, thoazoles, benzoxazoles y quinazolinas mediante el tratamiento de los mismos con diferentes tipos de nucleofilos tales como nucleofilos nitrogenados, oxigenados, o azufrados. Los compuestos producidos se trataron con oxido de propileno a diferentes concentraciones molares (n = 3, 5 y 7 para producir nuevos grupos de compuestos no iónicos que tuvieran la doble función de ser compuestos antimicrobianos y agentes de superficie, que se pudieran usar en la fabricación de medicinas, cosméticos, pesticidas o como antibacterianos o antifúngicos. Se determinaron sus propiedades tales como tensión superficial e interfacial, punto de turbidez, altura de espuma, tiempo de mojado, poder de emulsificación y concentración micelar crítica (CMC, asi como sus propiedades antimicrobianas y de degradabilidad.

  3. Imaging of amyloid deposition in human brain using positron emission tomography and [{sup 18}F]FACT: comparison with [{sup 11}C]PIB

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiroshi [National Institute of Radiological Sciences, Molecular Imaging Center, Chiba (Japan); National Institute of Radiological Sciences, Biophysics Program, Molecular Imaging Center, Chiba (Japan); Shinotoh, Hitoshi; Shimada, Hitoshi; Miyoshi, Michie; Takano, Harumasa; Takahashi, Hidehiko; Arakawa, Ryosuke; Kodaka, Fumitoshi; Ono, Maiko; Eguchi, Yoko; Higuchi, Makoto; Fukumura, Toshimitsu; Suhara, Tetsuya [National Institute of Radiological Sciences, Molecular Imaging Center, Chiba (Japan); Yanai, Kazuhiko; Okamura, Nobuyuki [Tohoku University School of Medicine, Department of Pharmacology, Sendai (Japan)

    2014-04-15

    The characteristic neuropathological changes in Alzheimer's disease (AD) are deposition of amyloid senile plaques and neurofibrillary tangles. The {sup 18}F-labeled amyloid tracer, [{sup 18}F]2-[(2-{(E)-2-[2-(dimethylamino)-1,3-thiazol-5-yl]vinyl}-1, 3-benzoxazol-6-yl)oxy ]-3-fluoropropan-1-ol (FACT), one of the benzoxazole derivatives, was recently developed. In the present study, deposition of amyloid senile plaques was measured by positron emission tomography (PET) with both [ {sup 11}C ]Pittsburgh compound B (PIB) and [ {sup 18}F ]FACT in the same subjects, and the regional uptakes of both radiotracers were directly compared. Two PET scans, one of each with [ {sup 11}C ]PIB and [ {sup 18}F ]FACT, were performed sequentially on six normal control subjects, two mild cognitive impairment (MCI) patients, and six AD patients. The standardized uptake value ratio of brain regions to the cerebellum was calculated with partial volume correction using magnetic resonance (MR) images to remove the effects of white matter accumulation. No significant differences in the cerebral cortical uptake were observed between normal control subjects and AD patients in [ {sup 18}F ]FACT studies without partial volume correction, while significant differences were observed in [ {sup 11}C ]PIB. After partial volume correction, the cerebral cortical uptake was significantly larger in AD patients than in normal control subjects for [ {sup 18}F ]FACT studies as well as [ {sup 11}C ]PIB. Relatively lower uptakes of [ {sup 11}C ]PIB in distribution were observed in the medial side of the temporal cortex and in the occipital cortex as compared with [ {sup 18}F ]FACT. Relatively higher uptake of [ {sup 11}C ]PIB in distribution was observed in the frontal and parietal cortices. Since [ {sup 18}F ]FACT might bind more preferentially to dense-cored amyloid deposition, regional differences in cerebral cortical uptake between [ {sup 11}C ]PIB and [ {sup 18}F ]FACT might be due to differences

  4. Imaging of amyloid deposition in human brain using positron emission tomography and [18F]FACT: comparison with [11C]PIB

    International Nuclear Information System (INIS)

    The characteristic neuropathological changes in Alzheimer's disease (AD) are deposition of amyloid senile plaques and neurofibrillary tangles. The 18F-labeled amyloid tracer, [18F]2-[(2-{(E)-2-[2-(dimethylamino)-1,3-thiazol-5-yl]vinyl}-1, 3-benzoxazol-6-yl)oxy ]-3-fluoropropan-1-ol (FACT), one of the benzoxazole derivatives, was recently developed. In the present study, deposition of amyloid senile plaques was measured by positron emission tomography (PET) with both [ 11C ]Pittsburgh compound B (PIB) and [ 18F ]FACT in the same subjects, and the regional uptakes of both radiotracers were directly compared. Two PET scans, one of each with [ 11C ]PIB and [ 18F ]FACT, were performed sequentially on six normal control subjects, two mild cognitive impairment (MCI) patients, and six AD patients. The standardized uptake value ratio of brain regions to the cerebellum was calculated with partial volume correction using magnetic resonance (MR) images to remove the effects of white matter accumulation. No significant differences in the cerebral cortical uptake were observed between normal control subjects and AD patients in [ 18F ]FACT studies without partial volume correction, while significant differences were observed in [ 11C ]PIB. After partial volume correction, the cerebral cortical uptake was significantly larger in AD patients than in normal control subjects for [ 18F ]FACT studies as well as [ 11C ]PIB. Relatively lower uptakes of [ 11C ]PIB in distribution were observed in the medial side of the temporal cortex and in the occipital cortex as compared with [ 18F ]FACT. Relatively higher uptake of [ 11C ]PIB in distribution was observed in the frontal and parietal cortices. Since [ 18F ]FACT might bind more preferentially to dense-cored amyloid deposition, regional differences in cerebral cortical uptake between [ 11C ]PIB and [ 18F ]FACT might be due to differences in regional distribution between diffuse and dense-cored amyloid plaque shown in the autoradiographic

  5. 3-D QSAR CoMFA study of nitrogen mustards possessing new chemical entities as possible anticancer agents

    Directory of Open Access Journals (Sweden)

    Anand R

    2006-01-01

    Full Text Available This present work is an investigation of anticancer activities of the nitrogen mustards possessing quinazolinone, benzimidazole, benzoxazole, and benzothiazole nuclei by the three-dimensional Quantitative Structure Activity paradigm, Comparative Molecular Field Analysis. A total of 39 compounds were modelled in SYBYL 6.7 (Tripos, USA. The molecules were aligned by root-mean-square fit of atoms and field fit of the steric and electrostatic molecular fields and the resulting databases analysed by partial least squares analysis with cross-validation, leave-one-out and no validation to extract the optimum number of components. The analysis was then repeated with bootstrapping to give the final Quantitative Structure Activity Relationship models. Eight compounds, which were kept separately as test set, were used to test the predictive ability of the Comparative Molecular Field Analysis models. Out of the two models generated, one was found to be useful. The predicted activities of the test set were in good agreement with experimentally determined values.

  6. High pressure optical studies of crystalline anils and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hockert, E.N.; Drickamer, H.G.

    1977-12-01

    High pressure optical studies have been made on a series of crystalline therochromic and photochromic anils and model compounds. Measurements include absorption and emission peak locations and the integrated intensities of various absorption peaks including the uv peak and visible peaks introduced thermally or by irradiation at various temperatures and pressures. Emission yields were also obtained. For the thermochromic compounds there was a large increase in the equilibrium yield of the thermally induced peak with pressure (piezochromism), corresponding to a volume decrease of approx.1.2 cc/mole for 5-bromosalicylidene aniline (5BrSA). The emission peak shifts to lower energy and decreases in intensity primarily because of increased rate of the radiationless conversion. For salicylidene aniline and related photochromic crystals the rate of photochromic conversion varied with both pressure and temperature in a manner which depends on the size of the energy barriers to the forward and reverse processes. The emission yield increases with pressure at low pressure, goes through a maximum, and decreases at high pressure. At low pressure the dominant feature is increase in occupation of the emitting state while at high pressure the increased rate of the radiationless process governs. For 2- (O-hydroxyphenyl) benzoxazole (OHBO) (see Fig. 1), where a keto--enol rearrangement is most probable, the changes in absorption and emission intensity can be related to the same diagram used for the anils. This diagram also describes the behavior of benzilidene aniline (BA), where only a cis--trans isomerization is possible.

  7. Synthesis, structure, photophysical and catalytic properties of CuI-Iodide complexes of di-imine ligands

    Science.gov (United States)

    Mondal, Jahangir; Ghorai, Anupam; Singh, Sunil K.; Saha, Rajat; Patra, Goutam K.

    2016-03-01

    Two new multifunctional CuII based complexes [CuI(L1)] (1) and [Cu2(μ-I)2(L2)] (2) with bidentate N-N donor ligands L1 and imino-pyridyl ligand L2 have been synthesized and characterized by elemental analysis, IR, UV-Vis, NMR and single crystal X-ray crystallography. The bidentate di-imine ligand (L1) forms monomeric CuI complex (1) whereas the bis-bidentate di-imine ligand (L2) favours the formation of dimeric CuI complex (2) in association with two bridging iodides. Structural analysis reveals that in complex 1 each monomeric units are connected by π⋯π and C-H⋯π interactions to form 3D supramolecular structure whereas in complex 2 each molecules are connected by only π⋯π interactions to form 3D supramolecular structure. The photoluminescence properties of the complexes have been studied at room temperature. Theoretical analysis shows that HOMO is focused on the Cu and iodides while LUMO is focused on di-imine ligands and the luminescence behaviour arises due to metal to ligand charge transfer (MLCT) and halide to ligand charge transfer (XLCT). The complexes 1 and 2 are effective catalysts for the synthesis of 2-substituted benzoxazoles.

  8. Photophysical properties of hydroxyphenyl benzazoles and their applications as fluorescent probes to study local environment in DNA, protein and lipid.

    Science.gov (United States)

    Sulaiman, Saba A J; Al-Rasbi, Ghalia S; Abou-Zied, Osama K

    2016-05-01

    Fluorescence techniques have drawn increasing attention because they provide crucial information about molecular interactions in protein-ligand systems beyond that obtained by other methods. The advantage of fluorescence spectroscopy stems from the fact that the majority of molecules in biological systems do not exhibit fluorescence, making fluorescent probes useful with high sensitivity. Also, the fluorescence emission is highly sensitive to the local environment, providing a valuable tool to investigate the nature of binding sites in macromolecules. In this review, we discuss some of the important applications of a class of molecules that have been used as fluorescent probes in a variety of studies. Hydroxyphenyl benzazoles (HBXs) show distinct spectroscopic features that make them suitable probes for the study of certain biological mechanisms in DNA, protein and lipid. In particular, the complex photophysics of 2-(2'-hydroxyphenyl)benzoxazole (HBO) and the distinguished fluorescence signatures of its different tautomeric forms make this molecule a useful probe in several applications. Among these are probing the DNA local environment, study of the flexibility and specificity of protein-binding sites, and detecting the heterogeneity and ionization ability of the head groups of different lipidic phases. The spectroscopy of HBX molecules and some of their chemically modified structures is also reviewed. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26910188

  9. Characterization of paliperidone photodegradation products by LC-Q-TOF multistage mass spectrometry.

    Science.gov (United States)

    Skibiński, Robert; Komsta, Łukasz; Inglot, Tadeusz

    2016-06-01

    The photodegradation of paliperidone in aqueous and methanol media under UVA and UVC irradiation was investigated. The identification and structural elucidation of its photodegradation products were performed by the use of the reversed-phase liquid chromatography coupled with accurate mass hybrid Q-TOF mass spectrometry and an atmospheric pressure chemical ionization source. Five degradation products were found and their masses were obtained with high accuracy (1.10-5.26 ppm) based on the TOF (MS) spectra. For the structural elucidation of unknown degradation products MS/MS spectra were also registered. However, for the identification of the main photodegradation product (3-{2-[4-(6-fluoro-1,3-benzoxazol-2-yl)piperidin-1-yl]ethyl}-9-hydroxy-2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidin-4-one) in-source fragmentation connected with collision-induced dissociation was used and MS(3) spectra were finally performed. The photodegradation of paliperidone yields the first-order kinetics in all tested conditions. The aqueous medium was in this case much less stable than the methanol solvent regardless of the irradiation source. Additionally, the toxicity of the analyzed photodegradation products was predicted by the use of ECOSAR software and comparable values of LC50 for the main degradants and the parent compound were obtained. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26400838

  10. Mechanism of Action and Clinical Application of Tafamidis in Hereditary Transthyretin Amyloidosis.

    Science.gov (United States)

    Coelho, Teresa; Merlini, Giampaolo; Bulawa, Christine E; Fleming, James A; Judge, Daniel P; Kelly, Jeffery W; Maurer, Mathew S; Planté-Bordeneuve, Violaine; Labaudinière, Richard; Mundayat, Rajiv; Riley, Steve; Lombardo, Ilise; Huertas, Pedro

    2016-06-01

    Transthyretin (TTR) transports the retinol-binding protein-vitamin A complex and is a minor transporter of thyroxine in blood. Its tetrameric structure undergoes rate-limiting dissociation and monomer misfolding, enabling TTR to aggregate or to become amyloidogenic. Mutations in the TTR gene generally destabilize the tetramer and/or accelerate tetramer dissociation, promoting amyloidogenesis. TTR-related amyloidoses are rare, fatal, protein-misfolding disorders, characterized by formation of soluble aggregates of variable structure and tissue deposition of amyloid. The TTR amyloidoses present with a spectrum of manifestations, encompassing progressive neuropathy and/or cardiomyopathy. Until recently, the only accepted treatment to halt progression of hereditary TTR amyloidosis was liver transplantation, which replaces the hepatic source of mutant TTR with the less amyloidogenic wild-type TTR. Tafamidis meglumine is a rationally designed, non-NSAID benzoxazole derivative that binds with high affinity and selectivity to TTR and kinetically stabilizes the tetramer, slowing monomer formation, misfolding, and amyloidogenesis. Tafamidis is the first pharmacotherapy approved to slow the progression of peripheral neurologic impairment in TTR familial amyloid polyneuropathy. Here we describe the mechanism of action of tafamidis and review the clinical data, demonstrating that tafamidis treatment slows neurologic deterioration and preserves nutritional status, as well as quality of life in patients with early-stage Val30Met amyloidosis. PMID:26894299

  11. trans-thionate derivatives of Pt(II) and Pd(II) with water-soluble phosphane PTA and DAPTA ligands: antiproliferative activity against human ovarian cancer cell lines.

    Science.gov (United States)

    Guerrero, Elena; Miranda, Susana; Lüttenberg, Sebastian; Fröhlich, Nils; Koenen, Jan-Moritz; Mohr, Fabian; Cerrada, Elena; Laguna, Mariano; Mendía, Aránzazu

    2013-06-01

    A series of PTA and DAPTA platinum(II) and palladium(II) thionate complexes of the type trans-[M(SN)2P2] were prepared from the reaction of cis-[MCl2P2] [M = Pt, Pd; P = PTA (1,3,5-triaza-7-phosphaadamantane), DAPTA (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane)] with the in situ generated sodium salts of the heterocyclic thiones S-m-methylpyrimidine-2-thione, S-4,6-dimethylpyrimidine-2-thione, S-4,6-dihydroxypyrimidine-2-thione, benzothiazole-2-thione, benzoxazole-2-thione, S-1,3,4,-thiadiazole-2-thione, S-4,5-H-thiazolan-2-thione, and S-pyrimidine-4(1H)-one-2-thione. The X-ray structures of six of the compounds confirm the trans disposition and, only in the case of [Pd2Cl2(S-pyrimidine-4(1H)-one-2-thionate)2(PTA)2], a dinuclear structure with a Pd-Pd distance of 3.0265(14)Å was observed. In vitro cytotoxicities against human ovarian cancer cell lines A2780 and A2780cisR were evaluated for ten complexes showing a high inhibition of cellular growth with a comparable inhibitory potency (IC50) against A2780 cells to that of cisplatin. Notably, the compounds also show significant (up to 7-fold higher) activity in cisplatin-resistant A2780cisR cell lines. PMID:23692403

  12. Monophthalocyanine complexes of samarium and terbium with axial ligands:synthesis, structure and optoelectronic properties

    Institute of Scientific and Technical Information of China (English)

    Alexander A Maleev; Mikhail N Bochkarev; Anatoly P Pushkarev; Vasily A Ilichev; Mikhail A Lopatin; Maxim A Samsonov; Georgy K Fukin; Georgy L Pakhomov; Vladislav V Travkin; Ivan D Grishin

    2014-01-01

    The monophthalocyanine complexes of samarium and terbium containing axial 2-mercaptobenzothiazole (PcSm(MBT) (1)), 2-(2-benzoxazol-2-yl) phenolate (PcTb(OON) (2)) or 2-(2-benzothiazol-2-yl)phenolate (PcTb(SON) (3)) ligands were synthe-sized and identified by elemental, LDI-TOF and X-ray (for 1) analysis. Photoluminescence (PL) and electroluminescence (EL) spec-tra of the compounds contained only emission bands of phthalocyanine and axial ligands but did not contain the bands of f-f transi-tions. It was found that among the complexes 1, 2, 3 the latter had highest photoconductivity (~10–7 S/cm) and photovoltaic properties. An organic photovoltaic device (OPV) of configuration of ITO/3/C60/Alq3/Al revealed open-circuit voltage (VOC) of 0.24 V and short current density (ISC) of 0.3μA/cm2 under illumination by a xenon lamp at 17 mW/cm2.

  13. Preparation of thermostable PBO/graphene nanocomposites with high dielectric constant

    International Nuclear Information System (INIS)

    In this study, poly(p-phenylene benzobisoxazole) (PBO)/graphene composites were prepared using PBO and poly(4,6-dihydroxymetaphenylenediamine terephthalamide) (PHA)-modified graphene oxide (GO–PHA). PHA is the precursor of PBO. GO–PHA was obtained via chemical coupling reaction of amino-terminated PHA and acyl-chloride-functionalized GO. Partially reduced graphene nanosheets and benzoxazole rings were formed after heating. GO–PHA could be stably dispersed in methane sulfonic acid (MSA), which facilitated its uniform distribution in the PBO matrix. The PBO/graphene nanocomposites were obtained by the dissolution of GO–PHA and PBO in MSA. The thermogravimetric analysis results showed that the PBO/graphene composites had good thermal stability below 400 ° C. The dielectric constant of the composites increased as the amount of GO–PHA increased, and the percolation threshold was fc = 0.037. The nanocomposite had a dielectric constant of 15.8, which was approximately five times larger than that of pure PBO polymer. (paper)

  14. Synthesis of Some New Heterocycles Derived from Phenylacetyl Isothiocyanate

    Institute of Scientific and Technical Information of China (English)

    HEMDAN M.M.; FAHMY A.F.; ALI N.F.; HEGAZI E.; ABD-ELHALEEM A.

    2008-01-01

    Phenylacetyl isothiocyanate (1) was reacted with benzoyl hydrazine (2a) in acetonitrile to give thiosemicarbazide derivative 3 which was cyclized by polyphosphoric acid to give 1,2,4-triazoline-5-thione derivative 4.Treatment of 1 with thiosemicarbazide (2b) yielded another 1,2,4-triazoline-5-thione derivative 5.Similar treatment of 1 with phenyl hydrazine (2c) in acetonitrile gave a differently substituted 1,2,4-triazoline-5-thione derivative 6 in one pot-reaction.On the other hand, when the reaction was carried out in acetone, a mixture of 6 and thiadiazolidine derivative 7 was obtained.However, reaction of 1 with hydrazine hydrate (2d) gave hydrazine derivative 8.Reaction of isothiocyanate 1 with anthranilic acid (9) gave benzo[d][1,3,6]oxazin-1-one derivative 10.Treatment of 1 with 2-aminothiophenol (11a), 2-aminophenol (11b) or o-phenylenediamine (11c) produced benzothiazole derivative 12a, benzoxazole derivative 12b and benzimidazole derivative 12c, respectively.The structures of all the products were confirmed by micro-analytical and spectral data.

  15. Efficient and versatile catalysis of N-alkylation of heterocyclic amines with alcohols and one-pot synthesis of 2-aryl substituted benzazoles with newly designed ruthenium(II) complexes of PNS thiosemicarbazones.

    Science.gov (United States)

    Ramachandran, Rangasamy; Prakash, Govindan; Selvamurugan, Sellappan; Viswanathamurthi, Periasamy; Malecki, Jan Grzegorz; Ramkumar, Venkatachalam

    2014-06-01

    Ruthenium(II) carbonyl complexes with phosphine-functionalized PNS type thiosemicarbazone ligands [RuCl(CO)(EPh3)(L)] (1-6) (E = P or As, L = 2-(2-(diphenylphosphino)benzylidene) thiosemicarbazone (PNS-H), 2-(2-(diphenylphosphino)benzylidene)-N-methylthiosemicarbazone (PNS-Me), 2-(2-(diphenylphosphino)benzylidene)-N-phenylthiosemicarbazone (PNS-Ph)) have been synthesized and characterized by elemental analysis and spectroscopy (IR, UV-Vis, (1)H, (13)C, (31)P-NMR) as well as ESI mass spectrometry. The molecular structures of complexes 1, 2 and 6 were identified by means of single-crystal X-ray diffraction analysis. The analysis revealed that all the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate PNS fashion. All the ruthenium complexes (1-6) were tested as catalyst for N-alkylation of heteroaromatic amines with alcohols. Notably, complex 2 was found to be a very efficient and versatile catalyst towards N-alkylation of a wide range of heterocyclic amines with alcohols. Complex 2 can also catalyze the direct amination of 2-nitropyridine with benzyl alcohol to the corresponding secondary amine. Furthermore, a preliminary examination of performance for N,N-dialkylation of diamine showed promising results, giving good conversion and high selectivity. In addition, N-alkylation of ortho-substituted anilines (-NH2, -OH and -SH) led to the one-pot synthesis of 2-aryl substituted benzimidazoles, benzoxazoles and benzothiazoles, also revealing the catalytic activity of complex 2. PMID:24705796

  16. Estrogen receptor beta-selective agonists stimulate calcium oscillations in human and mouse embryonic stem cell-derived neurons.

    Directory of Open Access Journals (Sweden)

    Lili Zhang

    Full Text Available Estrogens are used extensively to treat hot flashes in menopausal women. Some of the beneficial effects of estrogens in hormone therapy on the brain might be due to nongenomic effects in neurons such as the rapid stimulation of calcium oscillations. Most studies have examined the nongenomic effects of estrogen receptors (ER in primary neurons or brain slices from the rodent brain. However, these cells can not be maintained continuously in culture because neurons are post-mitotic. Neurons derived from embryonic stem cells could be a potential continuous, cell-based model to study nongenomic actions of estrogens in neurons if they are responsive to estrogens after differentiation. In this study ER-subtype specific estrogens were used to examine the role of ERalpha and ERbeta on calcium oscillations in neurons derived from human (hES and mouse embryonic stem cells. Unlike the undifferentiated hES cells the differentiated cells expressed neuronal markers, ERbeta, but not ERalpha. The non-selective ER agonist 17beta-estradiol (E(2 rapidly increased [Ca2+]i oscillations and synchronizations within a few minutes. No change in calcium oscillations was observed with the selective ERalpha agonist 4,4',4''-(4-Propyl-[1H]-pyrazole-1,3,5-triyltrisphenol (PPT. In contrast, the selective ERbeta agonists, 2,3-bis(4-Hydroxyphenyl-propionitrile (DPN, MF101, and 2-(3-fluoro-4-hydroxyphenyl-7-vinyl-1,3 benzoxazol-5-ol (ERB-041; WAY-202041 stimulated calcium oscillations similar to E(2. The ERbeta agonists also increased calcium oscillations and phosphorylated PKC, AKT and ERK1/2 in neurons derived from mouse ES cells, which was inhibited by nifedipine demonstrating that ERbeta activates L-type voltage gated calcium channels to regulate neuronal activity. Our results demonstrate that ERbeta signaling regulates nongenomic pathways in neurons derived from ES cells, and suggest that these cells might be useful to study the nongenomic mechanisms of estrogenic compounds.

  17. C-H and N-H bond dissociation energies of small aromatic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Barckholtz, C.; Barckholtz, T.A.; Hadad, C.M.

    1999-01-27

    A survey of computational methods was undertaken to calculate the homolytic bond dissociation energies (BDEs) of the C-H and N-H bonds in monocyclic aromatic molecules that are representative of the functionalities present in coal. These include six-membered rings (benzene, pyridine, pyridazine, pyrimidine, pyrazine) and five-membered rings (furan, thiophene, pyrrole, oxazole). By comparison of the calculated C-H BDEs with the available experimental values for these aromatic molecules, the B3LYP/6-31G(d) level of theory was selected to calculate the BDEs of polycyclic aromatic hydrocarbons (PAHs), including carbonaceous PAHs (naphthalene, anthracene, pyrene, coronene) and heteroatomic PAHs (benzofuran, benzothiophene, indole, benzoxazole, quinoline, isoquinoline, dibenzofuran, carbazole). The cleavage of a C-H or a N-H bond generates a {sigma} radical that is, in general, localized at the site from which the hydrogen atom was removed. However, delocalization of the unpaired electron results in {approximately} 7 kcal {center{underscore}dot} mol{sup {minus}1} stabilization of the radical with respect to the formation of phenyl when the C-H bond is adjacent to a nitrogen atom in the azabenzenes. Radicals from five-membered rings are {approximately} 6 kcal {center{underscore}dot} mol{sup {minus}1} less stable than those formed from six-membered rings due to both localization of the spin density and geometric factors. The location of the heteroatoms in the aromatic ring affects the C-H bond strengths more significantly than does the size of the aromatic network. Therefore, in general, the monocyclic aromatic molecules can be used to predict the C-H BDE of the large PAHs within 1 kcal {center{underscore}dot} mol{sup {minus}1}.

  18. Pitfalls of voxel-based amyloid PET analyses for diagnosis of Alzheimer's disease. Artifacts due to non-specific uptake in the white matter and the skull

    International Nuclear Information System (INIS)

    Two methods are commonly used in brain image voxel-based analyses widely used for dementia work-ups: 3-dimensional stereotactic surface projections (3D-SSP) and statistical parametric mapping (SPM). The methods calculate the Z-scores of the cortical voxels that represent the significance of differences compared to a database of brain images with normal findings, and visualize them as surface brain maps. The methods are considered useful in amyloid positron emission tomography (PET) analyses to detect small amounts of amyloid-β deposits in early-stage Alzheimer's disease (AD), but are not fully validated. We analyzed the 11C-labeled 2-(2-[2-dimethylaminothiazol-5-yl]ethenyl)-6-(2-[fluoro]ethoxy)benzoxazole (BF-227) amyloid PET imaging of 56 subjects (20 individuals with mild cognitive impairment [MCl], 19 AD patients, and 17 non-demented [ND] volunteers) with 3D-SSP and the easy Z-score imaging system (eZIS) that is an SPM-based method. To clarify these methods' limitations, we visually compared Z-score maps output from the two methods and investigated the causes of discrepancies between them. Discrepancies were found in 27 subjects (9 MCl, 13 AD, and 5 ND). Relatively high white matter uptake was considered to cause higher Z-scores on 3D-SSP in 4 subjects (1 MCl and 3 ND). Meanwhile, in 17 subjects (6 MCl, 9 AD, and 2 ND), Z-score overestimation on eZIS corresponded with high skull uptake and disappeared after removing the skull uptake ('scalping'). Our results suggest that non-specific uptakes in the white matter and skull account for errors in voxel-based amyloid PET analyses. Thus, diagnoses based on 3D-SSP data require checking white matter uptake, and 'scalping' is recommended before eZIS analysis. (author)

  19. Redox induced switching dynamics of a three colour electrochromic metallopolymer film

    International Nuclear Information System (INIS)

    Thin films of a novel Ru-phenolate based metallopolymer, [Ru(terpy)(box)PVP20]PF6, in which one in every twenty of the 4-vinyl pyridine monomer units is labelled with the ruthenium complex have been formed on glassy carbon electrodes, terpy is 2,2':6',2''-terpyridine, box is 2-(2-hydroxyphenyl)benzoxazole, and PVP is poly(4-vinylpyridine). Cyclic voltammetry and Raman spectroscopy reveal that the Ru2+/3+ couple is electrochemically reversible but that the phenolate ligand based oxidation is irreversible. These redox processes are associated with reversible colour changes from wine red (reduced) to red orange (mixed composition) then to light green (oxidized) in the visible region and an irreversible change in the near-IR region, respectively. Scanning electron microscopy reveals that repeated switching in LiClO4 aqueous solution does not induce any significant structural change within the deposit films. Cyclic voltammetry has been used to determine the electrochromic switching rate under semi-infinite linear diffusion conditions. In aqueous LiClO4, the homogeneous charge transport diffusion coefficient, DCT, decreases from 3.6 ± 0.3 x 10-13 to 2.7 ± 0.2 x 10-13 cm2 s-1 as the LiClO4 concentration increases from 0.1 to 1.0 M. This weak dependence of DCT on electrolyte concentration suggests that counterion availability is not rate-determining and that the overall rate of charge transport through the metallopolymer film is limited by the rate of segmental polymer chain motion necessary to bring adjacent centres sufficiently close to allow electron transfer to occur. Also the impact of changing the identity of the charge compensating anion of the redox electrochromic switching rate has been investigated. Finally, the electronic conductivity has been determined using interdigitated array electrodes (IDAs)

  20. Steady-state spectroscopy of new biological probes

    Science.gov (United States)

    Abou-Zied, Osama K.

    2007-02-01

    The steady state absorption and fluorescence spectroscopy of 2-(2'-hydroxyphenyl)benzoxazole (HBO) and (2,2'-bipyridine)-3,3'-diol (BP(OH) II) were studied here free in solution and in human serum albumin (HSA) in order to test their applicability as new biological probes. HBO and BP(OH) II are known to undergo intramolecular proton transfers in the excited state. Their absorption and fluorescence spectra are sensitive to environmental change from hydrophilic to hydrophobic, thus allowing the opportunity to use them as environment-sensitive probes. The effect of water on the steady state spectra of the two molecules also shows unique features which may position them as water sensors in biological systems. For HBO in buffer, fluorescence is only due to the syn-keto tautomer, whereas in HSA the fluorescence is due to four species in equilibrium in the excited state (the syn-keto tautomer, the anti-enol tautomer, the solvated syn-enol tautomer, and the anion species of HBO). Analysis of the fluorescence spectra of HBO in HSA indicates that HBO is exposed to less water in the HBO:HSA complex. For the BP(OH) II molecule, unique absorption due to water was observed in the spectral region of 400-450 nm. This absorption decreases in the presence of HSA due to less accessibility to water as a result of binding to HSA. Fluorescence of BP(OH) II is due solely to the di-keto tautomer after double proton transfer in the excited state. The fluorescence peak of BP(OH) II shows a red-shift upon HSA recognition which is attributed to the hydrophobic environment inside the binding site of HSA. We discuss also the effect of probe-inclusion inside well-defined hydrophobic cavities of cyclodextrins.

  1. 2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties.

    Science.gov (United States)

    Sayapin, Yury A; Tupaeva, Inna O; Kolodina, Alexandra A; Gusakov, Eugeny A; Komissarov, Vitaly N; Dorogan, Igor V; Makarova, Nadezhda I; Metelitsa, Anatoly V; Tkachev, Valery V; Aldoshin, Sergey M; Minkin, Vladimir I

    2015-01-01

    A series of derivatives of 2-hetaryl-1,3-tropolone (β-tropolone) was prepared by the acid-catalyzed reaction of 2-methylbenzoxazoles, 2-methylbenzothiazoles and 2,3,3-trimethylindoline with 3,4,5,6-tetrachloro-1,2-benzoquinone. The molecular structures of the three representative compounds were determined by X-ray crystallography. In crystal and (as shown by the DFT PBE0/6-311+G** calculations) in solution, 2-hetaryl-4,5,6,7-tetrachloro- and 2-hetaryl-5,6,7-trichloro-1,3-tropolones exist in the NH-tautomeric form with a strong resonance-assisted intramolecular N-H···O hydrogen bond. The mechanism of the formation of 1,3-tropolones in the reaction of methylene-active five-membered heterocycles with o-chloranil in acetic acid solution has been studied using density functional theory (DFT) methods. The reaction of 2-(2-benzoxa(thia)zolyl)-5,6,7-trichloro(4,5,6,7-tetrachloro)-1,3-tropolones with alcohols leads to the contraction of the seven-membered tropone ring with the formation of 2-(2-benzoxa(thia)zolyl)-6-alkoxycarbonylphenols. The molecular structure of 2-(2-ethoxycarbonyl-6-hydroxy-3,4,5-trichlorophenyl)benzoxazole has been determined by X-ray diffraction. 2-(2-Benzoxa(thia)zolyl)-6-alkoxycarbonylphenols display intense green fluorescence with anomalous Stokes shifts caused by the excited state intramolecular proton transfer (ESIPT) effects. PMID:26664640

  2. Synthesis of a New Fluorescent Brightener and Their Use in Plastic%一种新荧光增白剂的合成及其在塑料中的应用

    Institute of Scientific and Technical Information of China (English)

    胡义娇; 徐会志; 金可刚; 陈昱; 单雅丽; 程德文

    2011-01-01

    A new kind of fluorescent brightener,4,4′-bis(5-tert-butyl-benzoxazol-2-yl)stilbene,has been synthesized from 4-cyanobenzyl chloride and 4-butyl-2-aminophenol by two steps.It was found that the whitening effects of the product on PE(polyethylene),PP(polypropylene),PVC(polyvinylchlorid) and PET(polyethylene terephthalate) were good.The proper concentration for PE was 0.005% to 0.02% by weight.Comparing with other bisbenzoxazole stilbene fluorescent brightener such as OB-1 and OB-2,it presented better whitening effect when whitening PP.%本文介绍了4,4'-双(对叔丁基苯并噁唑-2-基)二苯乙烯的合成方法。以对氰基氯苄和对叔丁基邻氨基苯酚为原料分两步合成而制得。将制得的荧光增白剂用于PE(聚乙烯)、PP(聚丙烯)、PVC(聚氯乙烯)、PET(聚对苯二甲酸乙二醇酯),均有较好的增白效果。通过实验得到在PE上的合适添加量为0.005%~0.02%。与目前市场上常用的其他双苯并噁唑二苯乙烯类荧光增白剂如荧光增白剂OB-1、OB-2相比,在PP上的增白效果更优异。

  3. Linear and nonlinear modeling of antifungal activity of some heterocyclic ring derivatives using multiple linear regression and Bayesian-regularized neural networks.

    Science.gov (United States)

    Caballero, Julio; Fernández, Michael

    2006-01-01

    Antifungal activity was modeled for a set of 96 heterocyclic ring derivatives (2,5,6-trisubstituted benzoxazoles, 2,5-disubstituted benzimidazoles, 2-substituted benzothiazoles and 2-substituted oxazolo(4,5-b)pyridines) using multiple linear regression (MLR) and Bayesian-regularized artificial neural network (BRANN) techniques. Inhibitory activity against Candida albicans (log(1/C)) was correlated with 3D descriptors encoding the chemical structures of the heterocyclic compounds. Training and test sets were chosen by means of k-Means Clustering. The most appropriate variables for linear and nonlinear modeling were selected using a genetic algorithm (GA) approach. In addition to the MLR equation (MLR-GA), two nonlinear models were built, model BRANN employing the linear variable subset and an optimum model BRANN-GA obtained by a hybrid method that combined BRANN and GA approaches (BRANN-GA). The linear model fit the training set (n = 80) with r2 = 0.746, while BRANN and BRANN-GA gave higher values of r2 = 0.889 and r2 = 0.937, respectively. Beyond the improvement of training set fitting, the BRANN-GA model was superior to the others by being able to describe 87% of test set (n = 16) variance in comparison with 78 and 81% the MLR-GA and BRANN models, respectively. Our quantitative structure-activity relationship study suggests that the distributions of atomic mass, volume and polarizability have relevant relationships with the antifungal potency of the compounds studied. Furthermore, the ability of the six variables selected nonlinearly to differentiate the data was demonstrated when the total data set was well distributed in a Kohonen self-organizing neural network (KNN). PMID:16205958

  4. p-Tolylimido rhenium(v) complexes with phenolate-based ligands: synthesis, X-ray studies and catalytic activity in oxidation with tert-butylhydroperoxide.

    Science.gov (United States)

    Gryca, Izabela; Machura, Barbara; Małecki, Jan Grzegorz; Kusz, Joachim; Shul'pina, Lidia S; Ikonnikov, Nikolay S; Shul'pin, Georgiy B

    2016-01-01

    The reactions of mer-[Re(p-NTol)X3(PPh3)2] (X = Cl, Br) with chelating phenolate-based ligands (2-(2-hydroxy-5-methylphenyl)benzotriazole (HL(1)), 2-(2-hydroxyphenyl)benzothiazole (HL(2)) or 2-(2-hydroxyphenyl)benzoxazole (HL(3))) afforded a series of p-tolylimido rhenium(v) complexes cis- or trans-(X,X)-[Re(p-NTol)X2(L)(PPh3)]·yMeCN (where X = Cl, Br; L = L(1), L(2), L(3) and y = 0-2) and [Re(p-NTol)X(L)(PPh3)2]Z·pPPh3 (where X = Cl, Br; Z = ReO4, PF6; L = L(1), L(2), L(3) and p = 0 or 1). The reported compounds were characterized by elemental analysis, FT-IR, NMR ((1)H, (13)C and (31)P) and X-ray crystallography. Interestingly, the halide ions of [Re(p-NTol)Cl2(L(1))(PPh3)]·MeCN (1) and [Re(p-NTol)Cl2(L(2))(PPh3)]·2MeCN (3) are in cis relative dispositions, whereas the complexes [Re(p-NTol)Br2(L)(PPh3)] (L(1) for 2, L(2) for 4 and L(3) for 6) and [Re(p-NTol)Cl2(L(3))(PPh3)] (5) were found to be trans-(X,X) isomers. The compounds [Re(p-NTol)X(L)(PPh3)2](PF6) (X = Cl, Br; L = L(1) and L(2)) and [Re(p-NTol)X(L(3))(PPh3)2](PF6)·PPh3 (X = Cl, Br) have been tested in oxidative catalysis. A few compounds exhibited very good catalytic properties in oxidation of alcohols with tert-BuOOH (TBHP) in acetonitrile solution at moderate temperatures. Complex [Re(p-NTol)Cl(L(2))(PPh3)2]PF6 (13) is the catalyst of choice for oxidation of 1-phenylethanol to acetophenone (in 80% yield; turnover number attained 290 after 30 h) and cyclooctanol to cyclooctanone (in 88% yield). Notably lower activity has been found in the oxidation of alkanes with TBHP. Product distribution in the oxidation of methylcyclohexane indicates some steric hindrance around the reaction center. PMID:26618894

  5. Redox induced switching dynamics of a three colour electrochromic metallopolymer film

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Qiang; McNally, Andrea; Keyes, Tia E. [National Centre for Sensor Research, Biomedical Diagnostics Institute, School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland); Forster, Robert J. [National Centre for Sensor Research, Biomedical Diagnostics Institute, School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland)], E-mail: robert.forster@dcu.ie

    2008-10-15

    Thin films of a novel Ru-phenolate based metallopolymer, [Ru(terpy)(box)PVP{sub 20}]PF{sub 6}, in which one in every twenty of the 4-vinyl pyridine monomer units is labelled with the ruthenium complex have been formed on glassy carbon electrodes, terpy is 2,2':6',2''-terpyridine, box is 2-(2-hydroxyphenyl)benzoxazole, and PVP is poly(4-vinylpyridine). Cyclic voltammetry and Raman spectroscopy reveal that the Ru{sup 2+/3+} couple is electrochemically reversible but that the phenolate ligand based oxidation is irreversible. These redox processes are associated with reversible colour changes from wine red (reduced) to red orange (mixed composition) then to light green (oxidized) in the visible region and an irreversible change in the near-IR region, respectively. Scanning electron microscopy reveals that repeated switching in LiClO{sub 4} aqueous solution does not induce any significant structural change within the deposit films. Cyclic voltammetry has been used to determine the electrochromic switching rate under semi-infinite linear diffusion conditions. In aqueous LiClO{sub 4}, the homogeneous charge transport diffusion coefficient, D{sub CT}, decreases from 3.6 {+-} 0.3 x 10{sup -13} to 2.7 {+-} 0.2 x 10{sup -13} cm{sup 2} s{sup -1} as the LiClO{sub 4} concentration increases from 0.1 to 1.0 M. This weak dependence of D{sub CT} on electrolyte concentration suggests that counterion availability is not rate-determining and that the overall rate of charge transport through the metallopolymer film is limited by the rate of segmental polymer chain motion necessary to bring adjacent centres sufficiently close to allow electron transfer to occur. Also the impact of changing the identity of the charge compensating anion of the redox electrochromic switching rate has been investigated. Finally, the electronic conductivity has been determined using interdigitated array electrodes (IDAs)

  6. Redox induced switching dynamics of a three colour electrochromic metallopolymer film

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Qiang; McNally, Andrea; Keyes, Tia E.; Forster, Robert J. [National Centre for Sensor Research, Biomedical Diagnostics Institute, School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland)

    2008-10-15

    Thin films of a novel Ru-phenolate based metallopolymer, [Ru(terpy)(box)PVP{sub 20}]PF{sub 6}, in which one in every twenty of the 4-vinyl pyridine monomer units is labelled with the ruthenium complex have been formed on glassy carbon electrodes, terpy is 2,2':6',2''-terpyridine, box is 2-(2-hydroxyphenyl)benzoxazole, and PVP is poly(4-vinylpyridine). Cyclic voltammetry and Raman spectroscopy reveal that the Ru{sup 2+/3+} couple is electrochemically reversible but that the phenolate ligand based oxidation is irreversible. These redox processes are associated with reversible colour changes from wine red (reduced) to red orange (mixed composition) then to light green (oxidized) in the visible region and an irreversible change in the near-IR region, respectively. Scanning electron microscopy reveals that repeated switching in LiClO{sub 4} aqueous solution does not induce any significant structural change within the deposit films. Cyclic voltammetry has been used to determine the electrochromic switching rate under semi-infinite linear diffusion conditions. In aqueous LiClO{sub 4}, the homogeneous charge transport diffusion coefficient, D{sub CT}, decreases from 3.6 {+-} 0.3 x 10{sup -13} to 2.7 {+-} 0.2 x 10{sup -13} cm{sup 2} s{sup -1} as the LiClO{sub 4} concentration increases from 0.1 to 1.0 M. This weak dependence of D{sub CT} on electrolyte concentration suggests that counterion availability is not rate-determining and that the overall rate of charge transport through the metallopolymer film is limited by the rate of segmental polymer chain motion necessary to bring adjacent centres sufficiently close to allow electron transfer to occur. Also the impact of changing the identity of the charge compensating anion of the redox electrochromic switching rate has been investigated. Finally, the electronic conductivity has been determined using interdigitated array electrodes (IDAs). (author)

  7. A selective orexin-1 receptor antagonist attenuates stress-induced hyperarousal without hypnotic effects.

    Science.gov (United States)

    Bonaventure, Pascal; Yun, Sujin; Johnson, Philip L; Shekhar, Anantha; Fitz, Stephanie D; Shireman, Brock T; Lebold, Terry P; Nepomuceno, Diane; Lord, Brian; Wennerholm, Michelle; Shelton, Jonathan; Carruthers, Nicholas; Lovenberg, Timothy; Dugovic, Christine

    2015-03-01

    Orexins (OXs) are peptides produced by perifornical (PeF) and lateral hypothalamic neurons that exert a prominent role in arousal-related processes, including stress. A critical role for the orexin-1 receptor (OX1R) in complex emotional behavior is emerging, such as overactivation of the OX1R pathway being associated with panic or anxiety states. Here we characterize a brain-penetrant, selective, and high-affinity OX1R antagonist, compound 56 [N-({3-[(3-ethoxy-6-methylpyridin-2-yl)carbonyl]-3-azabicyclo[4.1.0]hept-4-yl}methyl)-5-(trifluoromethyl)pyrimidin-2-amine]. Ex vivo receptor binding studies demonstrated that, after subcutaneous administration, compound 56 crossed the blood-brain barrier and occupied OX1Rs in the rat brain at lower doses than standard OX1R antagonists GSK-1059865 [5-bromo-N-({1-[(3-fluoro-2-methoxyphenyl)carbonyl]-5-methylpiperidin-2-yl}methyl)pyridin-2-amine], SB-334867 [1-(2-methyl-1,3-benzoxazol-6-yl)-3-(1,5-naphthyridin-4-yl)urea], and SB-408124 [1-(6,8-difluoro-2-methylquinolin-4-yl)-3-[4-(dimethylamino)phenyl]urea]. Although compound 56 did not alter spontaneous sleep in rats and in wild-type mice, its administration in orexin-2 receptor knockout mice selectively promoted rapid eye movement sleep, demonstrating target engagement and specific OX1R blockade. In a rat model of psychological stress induced by cage exchange, the OX1R antagonist prevented the prolongation of sleep onset without affecting sleep duration. In a rat model of panic vulnerability (involving disinhibition of the PeF OX region) to threatening internal state changes (i.e., intravenous sodium lactate infusion), compound 56 attenuated sodium lactate-induced panic-like behaviors and cardiovascular responses without altering baseline locomotor or autonomic activity. In conclusion, OX1R antagonism represents a novel therapeutic strategy for the treatment of various psychiatric disorders associated with stress or hyperarousal states. PMID:25583879

  8. Effect of 2-(2-Pyridyl)azole-based ancillary ligands (L1-4) on the electrophilicity of the nitrosyl function in [RuII(trpy)(L1-)4)(NO)]3+ [trpy = 2,2':6',2' '-Terpyridine]. synthesis, structures, and spectroscopic, electrochemical, and kinetic aspects.

    Science.gov (United States)

    Chanda, Nripen; Paul, Debamita; Kar, Sanjib; Mobin, Shaikh M; Datta, Anindya; Puranik, Vedavati G; Rao, K Krishnamurthy; Lahiri, Goutam Kumar

    2005-05-16

    Ruthenium nitrosyl complexes [Ru(trpy)(L(1-4))(NO)](3+) (13-16) [trpy = 2,2':6',2' '-terpyridine, L(1) = 2-(2-pyridyl)benzoxazole, L(2) = 2-(2-pyridyl)benzthiazole, L(3) = 2-(2-pyridyl)benzimidazole, L(4) = 1-methyl-2-(2-pyridyl)-1H-benzimidazole] were obtained in a stepwise manner starting from [Ru(II)(trpy)(L(1-4))(Cl)]ClO(4) (1-4) -->[Ru(II)(trpy)(L(1-4))(H(2)O)](ClO(4))(2) (5-8) --> [Ru(II)(trpy)(L(1-4)) (NO(2))]ClO(4) (9-12) --> [Ru(II)(trpy)(L(1,2,4))(NO)](ClO(4))(3) (13, 14, 16)/[Ru(II)(trpy)(L(3))(NO)](ClO(4))(2)(NO(3)) (15). Crystal structures of 1, 2, 4, 9, 12, 13, 15, and 16 established the stereoretentive nature of the transformation processes. Though the complexes of L(1), L(3), and L(4) were isolated in the isomeric form A (pi-acceptor trpy and azole ring in the equatorial plane and the pyridine and chloride donors in the axial positions), complexes of L(2) preferentially stabilized in form B (trpy and pyridine in the equatorial plane and the azole ring and chloride donors in the axial positions). The nu(NO) stretching frequency varied in the range of 1957-1932 cm(-1), 13 > 14 approximately 15 > 16, primarily depending on the electronic aspects of L as well as the isomeric structural forms. The coordinated nitrosyl function underwent successive reductions of [Ru(II)-NO(+)](3+) --> [Ru(II)-NO(*)](2+) and [Ru(II)-NO(*)](2+) --> [Ru(II)-NO(-)](+), and the first reduction potential follows the order 14 > 13 > 15 approximately 16. The nearly axial EPR spectra having nitrogen hyperfine splittings (A approximately 26 G) at 77 K of 13(-)-16(-) with g approximately 2.0 established that the reduction process is largely centered around the nitrosyl function. Despite an appreciably high nu(NO), the complexes were found to be unusually stable even in the aqueous medium. They transformed slowly and only partially into the corresponding nitro derivatives in H(2)O (k approximately 10(-4) s(-1) and K = 0.4-3.8). The chloro (1-4), aqua (5-8), and nitro (9

  9. 离子传感器材料Ir(ppy)2(O^N)配合物的结构和光谱特征%The Structures and Spectroscopic Properties of Ion Transducer Material Ir(ppy) 2 (O^N) Complexes

    Institute of Scientific and Technical Information of China (English)

    张建坡; 金丽; 李岩; 郝希云

    2014-01-01

    采用密度泛函方法对两种Ir(ppy)2(O^N)(ppy=2-苯基吡啶;O^N=2-(2-羟基苯)-苯并噻唑(1), O^N=2-(2-羟基苯)-苯并恶唑(2))配合物的几何结构和光谱特征进行了详细的理论研究。计算得到的Ir-N(1)、 Ir-N(3)和Ir-O(1)基态键长和相应实验值符合得较好。激发态下, Ir-N(1)和Ir-C(1)键长均增加了约0.02~0.05Å,而Ir-O(1)键长则缩短了大约0.02Å。在TD-DFT计算水平下结合极化连续介质( PCM)模型,得到1~2的最低能吸收和发射分别出现在484 nm(1)、441 nm (2)和624 nm(1)、519 nm(2)。1和2的此跃迁均属于[d(Ir)+π(ppy)+π(O^N)→π*(O^N)]的电荷转移跃迁。计算结果表明, ppy和O^N配体在跃迁过程中担当两个独立的发色团。与分子2相比,由于1在O^N配体上存在噻唑环,导致其分子整体结构变化较大,并使吸收和发射波长产生明显红移。%The geometries and spectroscopic properties of a series of Ir (ppy)2(O^N)(ppy=2-phenylpyridine;O^N=2-(2-Hydroxyphenyl) -benzothiazole (1), O^N =2 -(2 -hydroxyphenyl) -benzoxazole (2)) were investigated theoretically.The calculated bond lengths of Ir-N(1), Ir-N(3) and Ir-O(1) in the ground state agreed well with the corresponding experimental results.Upon excitation, the bond lengths of Ir -N(1) and Ir-C(1) lengthen by 0.02~0.05 Åand that of Ir-O(1) shortened by 0.02Å.At the TD-DFT level with the PCM model , 1~2 give rise to lowest -lying absorptions at 484(1), 441(2) nm and phosphorescent emissions at 624(1), 519(2) nm, respectively.The transitions of 1, 2 were attributed to [d(Ir)+π(ppy)+π(O^N)→π*(O^N)] charge transfer.The calculated results showed that the ppy and O^N groups acted as two independent chromospheres in transition processes.Compared with 2 , the geometric structure was greatly affected and the absorptions and emissions were red -shifted by

  10. A modified method of 3D-SSP analysis for amyloid PET imaging using [11C]BF-227

    International Nuclear Information System (INIS)

    Three-dimensional stereotactic surface projection (3D-SSP) analyses have been widely used in dementia imaging studies. However, 3D-SSP sometimes shows paradoxical results on amyloid positron emission tomography (PET) analyses. This is thought to be caused by errors in anatomical standardization (AS) based on an 18F-fluorodeoxyglucose (FDG) template. We developed a new method of 3D-SSP analysis for amyloid PET imaging, and used it to analyze 11C-labeled 2-(2-[2-dimethylaminothiazol-5-yl]ethenyl)-6-(2-[fluoro]ethoxy) benzoxazole (BF-227) PET images of subjects with mild cognitive impairment (MCI) and Alzheimer's disease (AD). The subjects were 20 with MCI, 19 patients with AD, and 17 healthy controls. Twelve subjects with MCI were followed up for 3 years or more, and conversion to AD was seen in 6 cases. All subjects underwent PET with both FDG and BF-227. For AS and 3D-SSP analyses of PET data, Neurostat (University of Washington, WA, USA) was used. Method 1 involves AS for BF-227 images using an FDG template. In this study, we developed a new method (Method 2) for AS: First, an FDG image was subjected to AS using an FDG template. Then, the BF-227 image of the same patient was registered to the FDG image, and AS was performed using the transformation parameters calculated for AS of the corresponding FDG images. Regional values were normalized by the average value obtained at the cerebellum and values were calculated for the frontal, parietal, temporal, and occipital lobes. For statistical comparison of the 3 groups, we applied one-way analysis of variance followed by the Bonferroni post hoc test. For statistical comparison between converters and non-converters, the t test was applied. Statistical significance was defined as p < 0.05. Among the 56 cases we studied, Method 1 demonstrated slight distortions after AS of the image in 16 cases and heavy distortions in 4 cases in which the distortions were not observed with Method 2. Both methods demonstrated that the

  11. Standards for multi-element IRMS within a single run

    International Nuclear Information System (INIS)

    occur. Another improvement is the opportunity to determine up to three isotopic ratios within a single run. This saves much time of labour (to weigh out the sample and to measure it). There has one problem to be solved. The portion of the element forming the biomass differ. Biomass consists of about 50 % carbon, but only 2 % nitrogen and less sulphur. Introducing the original outflow from the GC-column into the analyser will lead to exceeding peaks for at least one element. This problem can be solved by a diluting the gas outflow, e.g. that of carbon dioxide. Usually the IT programmes are also not suitable for multi-element measurements and must be adapted. Another problem are the standards. The number of standards to be distributed internationally and regularly is limited. The former idea to have a pair of standards for each matrix (food, juice, wine, etc.) available cannot be realized, because of many limitations, as homogeneity, storage, spoiling. One should also have standards which can be used as well for isotope ratio determinations as for the elemental analysis (content of an element of the sample). Therefore we will present our experience with a synthetic standard which has been calibrated against the international standards. In this case we have only one material, for further application would should use a pair of different isotopic composition. Their range should fit the natural scale. The material tested is 2,5.Bis-(-tert.-butyl-benzoxazol-2-yl)-thiophen. It sounds to be a complicated molecule but is not only available in larger quantities, is a homogeneous powder, not static charging, stable, non-poisonous and most important: It contains all the elements in quantities close to natural compounds except sulphur. But to hit the natural sulphur content the molecule should be much larger and perhaps not easily to synthesize. The elementary composition is: 72.46% carbon, 6.5 % nitrogen, 7.43% oxygen, 7.45% sulphur and 6.02% hydrogen. It has been tested as well in