- Bent Shaped 1,3,4-Oxadiazole/Thiadiazole heterocyclic rings containing liquid crystals
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Two series of bent shaped 1,3,4-oxadiazole/thiadiazole heterocyclic ring containing liquid crystalline (LC) compounds were synthesized and characterized by FT-IR, 1H, 13C-NMR and ESI-Mass spectroscopic techniques. Liquid crystal properties were investigated by polarized optical microscopy and differential scanning calorimetry. All the compounds exhibited mesophases such as nematic, smectic A and smectic C phases. The liquid crystalline effects were ascertained by changing the central atom in the heterocyclic ring and by increasing the length of the terminal alkyloxy chains which bring considerable improvements on the mesomorphic properties. The absorption and emission spectral studies of all the compounds were investigated and confirmed.
- Selvarasu, Chinnaiyan,Kannan, Palaninathan
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- Synthesis and photophysical study of some new highly thermostable blue fluorescent poly(1,3,4-oxadiazole-imide)s containing dimethylamine groups
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New poly(1,3,4-oxadiazole-imide)s were synthesized from a diamine containing 1,3,4-oxadiazole ring, 4,4′-diamino-4″-[(2-(4-phenoxy)-5-(4-dimethylaminophenyl)-1,3,4-oxadiazole]triphenylmethane, and different aromatic dianhydrides: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, 9,9-bis[(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) and perylene-3,4,9,10-tetracarboxylic dianhydride. The polymers were easily soluble in polar organic solvents and exhibited high thermal stability, having 5% weight loss in the range of 445-470 °C and glass transition temperature in the domain of 201-244 °C. The optical properties were investigated in different media. The absorption characteristics (intensity, absorption maximum and shape) of investigated compounds depended on their chemical structures and the nature of environment. The emission of these samples was represented by one broadened and blue emission band. The largest and solvent dependent Stokes shifts values were obtained. The fluorescence quantum yield (QY) values of polymer with hexafluoroisopropylidene groups, in tetrahydrofuran solution, depended on the wavelength used for excitation. This is an exception from Kasha's rule and Vavilov's law, which was attributed either to photodecomposition or to the enhancement of intramolecular energy transfer process competing with internal conversion between singlet states. High QY values were obtained for polymers with isopropylidene or fluorene units in dimethyl sulfoxide (polar solvent), which may be due to the strong overlap of electronic transitions of species from system.
- Hamciuc, Corneliu,Homocianu, Mihaela,Hamciuc, Elena,Carja, Ionela-Daniela
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- NITROGEN-CONTAINING BIOPOLYMER-BASED CATALYSTS, THEIR PREPARATION AND USES IN HYDROGENATION PROCESSES, REDUCTIVE DEHALOGENATION AND OXIDATION
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The present invention relates to a process for the preparation of a nitrogen containing biopolymer-based catalyst by pyrolysis of a metal complex with a nitrogen-containing biopolymer and to the nitrogen containing biopolymer-based catalysts obtainable by this process. In particular, the invention relates to a nitrogen containing biopolymer-based catalyst comprising metal particles and at least one nitrogen containing carbon layer. The invention also relates to the use of a nitrogen containing biopolymer-based catalyst in a hydrogenation process, preferably in a process for hydrogenation of nitroarenes, nitriles or imines; in a reductive dehalogenation process of C-X bonds, wherein X is CI, Br or I, preferably in a process for dehalogenation of organohalides or in a process for deuterium labelling of arenes via dehalogenation of organohalides; or in an oxidation process. Further, the invention relates to a metal complex with the nitrogen containing biopolymer, wherein the metal is a transition metal selected from the group consisting of manganese, ruthenium, cobalt, rhodium, nickel, palladium and platinum, preferably cobalt or nickel, and wherein the nitrogen containing biopolymer is selected from chitosan, chitin and a polyamino acid, preferably chitosan or chitin.
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Page/Page column 16; 31-33
(2018/07/29)
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- Biomass-Derived Catalysts for Selective Hydrogenation of Nitroarenes
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Development of catalytically active materials from biowaste represents an important aspect of sustainable chemical research. Three heterogeneous materials were synthesized from inexpensive biomass-based chitosan and abundant Co(OAc)2 using complexation followed by pyrolysis at various temperatures. These materials were applied in the catalytic hydrogenation of nitroarenes using molecular hydrogen. A variety of diversely functionalized nitroarenes including some pharmaceutically active compounds were converted into aromatic amines in high yields, with high selectivity, and with excellent functional group tolerance. This green protocol has also been implemented for the synthesis of a biologically important TRPC3 inhibitor.
- Sahoo, Basudev,Formenti, Dario,Topf, Christoph,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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p. 3035 - 3039
(2017/08/18)
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- Polytriazole bridged with 2,5-diphenyl-1,3,4-oxadiazole moieties: A highly sensitive and selective fluorescence chemosensor for Ag+
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Fluorescent conjugated polytriazoles (FCP 1-4) containing both 2,5-diphenyl-1,3,5-oxadiazole (OXD) and 1,2,3-triazole moieties in the main chain were synthesized from aromatic diazide (1) and dialkynes (2-5) via click polymerization, respectively. In the polymers, OXDs (fluorophores) and triazole rings (generated via CuAAC acting as metal ion ligands) comprise a fluorescent system. The polytriazoles displayed relatively strong emission with quantum yields in the range of 0.20-0.28 at room temperature in DMF. The study on their ion-responsive properties showed that, although all four FCPs have good selectivity for Ag+, the integration of alkoxy side groups (methoxy for FCP 2, hexyloxy for FCP 3 and 2-ethylhexyloxy for FCP 4) to the main chains of the polytriazoles decreased their sensitivity for Ag+via alteration of the polymer aggregation status and electron density of the main chains. Thus FCP 1 is highly sensitive for Ag+, where its Ksv is as high as 1.44 × 105 M-1 and its lowest detection limit is in the ppb range (4.22 × 10-7 M). This study provides an efficient click approach to the synthesis of a novel fluorescence sensor for Ag+ detection, which could expand the application of click polymerization in designing fluorescence sensors based on the triazole unit. This journal is
- Cao, Shoupeng,Pei, Zhichao,Xu, Yongqian,Zhang, Ruina,Pei, Yuxin
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p. 45888 - 45896
(2015/06/08)
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- Electrochemical oxidation of aldehyde-N-arylhydrazones into symmetrical-2,5-disubstituted-1,3,4-oxadiazoles
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A convenient, efficient and one-pot synthesis of chemically and pharmaceutically interesting symmetrical-2,5-disubstituted-1,3,4-oxadiazoles is reported. The protocol involves anodic oxidation of aldehyde-N-arylhydrazones in anhyd. MeCN-LiClO4. Constant potential electrolysis carried out in an undivided cell and platinum electrodes leads to the formation of the corresponding oxadiazoles under ambient condition and the mechanism was deduced from voltammetry studies. The reaction proceeded smoothly with high atom economy. Springer Science+Business Media Dordrecht 2013.
- Singh, Sushma,Sharma, Laxmi K.,Saraswat, Apoorv,Siddiqui, Ibadur R.,Singh, Rana K. Pal
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p. 947 - 960
(2014/05/06)
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- Electrosynthesis and screening of novel 1,3,4-oxadiazoles as potent and selective antifungal agents
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The electrochemical oxidation of aldehyde-N-aroylhydrazone has been studied in the presence of NaClO4 as supporting electrolyte in MeOH solution using cyclic voltammetry and controlled potential electrolysis. The results indicate that intramolecular cyclization of aldehyde-N-aroylhydrazone has been successfully performed at a platinum electrode in an undivided cell with good yields of the corresponding 1,3,4-oxadiazoles at ambient conditions. The reaction products were characterized by spectroscopic methods and a mechanism was deduced from voltammetry studies. The antifungal activity of the synthesized compounds was evaluated on Fusarium oxysporum, Alternaria solani, Candida albicans and Aspergillus niger. The results revealed that all the synthesized compounds have significant antifungal activity against the tested fungi. Among the synthesized derivatives 7b, 7d, 7g, 7h, 7i, 7j and 7r were found to be the most effective antifungal compounds. The Royal Society of Chemistry 2013.
- Singh, Sushma,Sharma, Laxmi Kant,Saraswat, Apoorv,Siddiqui, Ibadur R.,Kehri, Harbans K.,Singh, Rana K. Pal
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p. 4237 - 4245
(2013/05/08)
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- Nanoscale Fe2O3-based catalysts for selective hydrogenation of nitroarenes to anilines
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Production of anilines - key intermediates for the fine chemical, agrochemical, and pharmaceutical industries - relies on precious metal catalysts that selectively hydrogenate aryl nitro groups in the presence of other easily reducible functionalities. Herein, we report convenient and stable iron oxide (Fe2O3) - based catalysts as a more earth-abundant alternative for this transformation. Pyrolysis of iron-phenanthroline complexes on carbon furnishes a unique structure in which the active Fe2O 3 particles are surrounded by a nitrogen-doped carbon layer. Highly selective hydrogenation of numerous structurally diverse nitroarenes (more than 80 examples) proceeded in good to excellent yield under industrially viable conditions.
- Jagadeesh, Rajenahally V.,Surkus, Annette-Enrica,Junge, Henrik,Pohl, Marga-Martina,Radnik, Joerg,Rabeah, Jabor,Huan, Heming,Schunemann, Volker,Brueckner, Angelika,Beller, Matthias
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p. 1073 - 1076
(2014/01/06)
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- Copoly(peryleneimide)s containing 1,3,4-oxadiazole rings: Synthesis and properties
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New copolyimides containing perylenediimide, oxadiazole and hexafluoroisopropylidene moieties were prepared by one-step polycondensation reaction in solution at high temperature of aromatic diamines containing preformed oxadiazole ring with a mixture of a dianhydride having a perylene ring and another dianhydride with hexafluoroisopropylidene unit. The thermal stability and glass transition temperatures of these copolyimides were measured and compared with those of related polyimides. The solid polymers were also studied by polarized light microscopy and X-ray diffraction which revealed a semicrystalline state consisting of face-to-face arranged columns of perylenediimide units. The film-forming ability and properties of the resulting thin films were investigated by using atom force microscopy and scanning electron microscopy which showed that the films were organized into selfassembled rod-like structures. The UV-Vis and photoluminescence properties in solution and in solid state were also investigated.
- Rusu, Radu-Dan,Damaceanu, Mariana-Dana,Marin, Luminita,Bruma, Maria
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body text
p. 4230 - 4242
(2011/11/14)
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- Fluorinated heterocyclic polyperyleneimides
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New polyperyleneimides containing 1,3,4-oxadiazole rings and hexafluoroisopropylidene linkages were synthesized by solution polycondensation reaction at high temperature of aromatic diamines having oxadiazole rings with a mixture of perylenetetracarboxylic dianhydride and hexafluoroisopropylidene diphthalic dianhydride. The solubility and thermal stability of these polymers were studied and compared with those of related polyimides and polyoxadiazoles. The film-forming ability and the quality of the resulting thin films were investigated by using atom force microscopy and scanning electron microscopy, which showed that the films were organized into self-assembled rod-like structures. The photoluminescence of the polymers, both in solution and in solid state, after irradiation with light of different wavelengths, were also studied.
- Damaceanu, Mariana-Dana,Rusu, Radu-Dan,Bruma, Maria,Rusanov, Alexander
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experimental part
p. 953 - 961
(2012/02/14)
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- Aromatic polyoxadiazoles with silicon in the main chain
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This article presents a review on aromatic polymers which contain 1,3,4-oxadiazole rings and diphenylsilylene units in the main chain. These polymers have been synthesized by polycondensation reactions of certain monomers containing silicon, such as dicarboxylic acids, diacid chlorides, diesters or dihydrazides, with conventional aromatic dihydrazides or with aromatic diamines containing preformed oxadiazole rings. The properties of these polymers, such as solubility, film forming ability, thermal stability, electrochemical behavior and photoluminescence properties, and their potential applications are discussed.
- Bruma, Maria
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experimental part
p. 343 - 355
(2009/05/26)
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- Polyimides containing 1,3,4-oxadiazole rings
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Two series of polyimides containing 1,3,4-oxadiazole rings in the main chain, one of them having flexible hexafluoropropane-2,2-diyl groups and the other with carbonyl groups, were prepared by polycondensation of aromatic diamines containing 1,3,4-oxadiaz
- Bruma, Maria,Damaceanu, Mariana-Dana
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experimental part
p. 1631 - 1644
(2009/06/18)
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- 2,5-SUBSTITUTED OXAZOLE DERIVATIVES AS PROTEIN KINASE INHIBITORS FOR THE TREATMENT OF CANCER
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Certain oxazole-based compounds exhibiting ATP-utilizing enzyme inhibitory activity, methods of using compounds exhibiting ATP-utilizing enzyme inhibitory activity, and compositions comprising compounds exhibiting ATP-utilizing enzyme inhibitory activity, are disclosed.
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Page/Page column 66-67
(2010/11/29)
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- Poly(1,3,4-oxadiazole-ester-amide)s
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New aromatic poly (1,3,4-oxadiazole)s containing both amide and ester groups in the main chain have been synthesized and their properties have been determined and compared with those of wholly aromatic polyamides and poly(1,3,4-oxadiazole)s. These polymers show good thermal stability, with the initial decomposition temperature around 360°C and the glass transition temperature in the range 190°C-270°C. They are easily soluble in certain solvents such as N-methylpyrrolidinone, N,N′-dimethylacetamide and N,N′-dimethylformamide, and can be cast from solutions into thin flexible films.
- Sava, Ion,Iosip, Mariana-Dana,Bruma, Maria
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p. 515 - 523
(2007/10/03)
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- An efficient one pot synthesis of 1,3,4-oxadiazoles
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Various 1,3,4-oxadiazoles have been synthesized in excellent yields by BF3·Et2O promoted cyclodehydration of 1,2-diacyl and diaroyl hydrazines prepared in situ from corresponding acid chlorides and hydrazine.
- Tandon,Chhor
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p. 1727 - 1732
(2007/10/03)
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- Ethylenic silicon compounds and thermoplastic elastomers obtained therefrom
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The invention provides organosilicon compounds of the formula: STR1 in which: N IS 1, 2 OR 3; Each R, which may be identical or different, is a monovalent organic group which contains a carbon-carbon double bond and from 2 to 10 carbon atoms; Each R1, which may be identical or different, is a straight or branched alkyl radical optionally substituted by one or more halogen atoms or cyano groups; an aryl radical or an alkylaryl radical optionally substituted by one or more halogen atoms; R2 is a straight or branched divalent alkylene or alkylidene radical possessing up to 4 carbon atoms; X is a divalent radical consisting of, or containing, at least one hetero-atom selected from oxygen, sulphur and nitrogen atoms, the radical being attached to the radical R2 via a said hetero-atom; G is an organic radical of valency (m+ l) possess from 1 to 30 carbon atoms; m is 1, 2 or 3; And each Y, which may be identical or different, is a functional group selected from: --NO2, STR2 --COOM (where M represents a sodium, potassium or lithium atom); --COOR4 ; STR3 --COCl; --OH; --OR4 ; STR4 --SH; --SR4 ; STR5 --CONH2 ; --CSNH2 ; --CN; --CH2 --NH2 ; --CHO; STR6 --NCO; STR7 wherein R3 represents a hydrogen atom or a straight or branched alkyl radical possessing up to 6 carbon atoms and R4 represents an alkyl radical possessing up to 4 carbon atoms, with the proviso that two Y groups can together constitute an imide group STR8 wherein R5 represents a hydrogen atom or a straight or branched alkyl radical possessing up to 4 carbon atoms. These are useful intermediates in the preparation of disilanes and silicon polymers, in particular of polyethylenic silicon compounds which can be polymerized with an α, ω-dihydrogenopolysiloxane to give thermoplastic elastomers.
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