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Trifluoromethyl Groups (trifluoromethyl + groups)
Selected AbstractsSynthesis of Some Trifluoromethylated Cyclodextrin Derivatives and Analysis of Their Properties as Artificial Glycosidases and OxidasesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2007Jeannette Bjerre Abstract Cyclodextrin derivatives containing trifluoromethyl groups at C6 of the A and D rings were synthesized for the purpose of creating artificial enzymes. The compounds were synthesized by perbenzylation of ,-cyclodextrin followed by selective A,D-debenzylation according to Sinaÿ. Subsequent oxidation to dialdehyde with Dess,Martin periodinane followed by addition of CF3 by using Arduengo carbene and TMSCF3 led to the C6 -bistrifluoromethylated alcohols. These were either deprotected by hydrogenolysis or subjected to another round of oxidation to provide the corresponding ketones that were deprotected. The trifluoromethylated alcohols were found to be weak artificial enzymes catalysing hydrolysis of nitrophenyl glycosides at neutral pH with a kcat/kuncat of up to 56. It is proposed that this catalysis is analogues to the catalysis performed by related cyanohydrins. The trifluoro ketones were likewise weak articial enzymes catalysing oxidation of amines to nitro derivatives or alcohols to ketones with a kcat/kuncat of up to 133. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis of bipolar charge transporting block copolymers and characterization for organic light-emitting diodeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2010Kousuke Tsuchiya Abstract A series of hole and electron transporting random and block copolymers consisting of triphenylamine moiety as a hole transporting unit and oxadiazole moiety as an electron transporting unit have been prepared via a nitroxide mediated radical polymerization. Oxadiazole monomers with t -butyl or trifluoromethyl groups, 2 and 7, respectively, were used for copolymerization. Photoluminescent measurements of polymers revealed that the formation of the exciplex between triphenylamine and oxadiazole units tends to occur in the order of random copolymers, block copolymers, and polymer blends, implying phase-separated morphologies in block or blend systems. The polymers were applied for OLED devices, and we found that the morphology in the polymer layer critically affected device performance. The block copolymer comprising hole and electron transporting units with the composition of 14/86 showed the highest external quantum efficiency over 10%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1461,1468, 2010 [source] Synthesis and characterization of a series of diverse poly(2-oxazoline)sJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2009Kristian Kempe Abstract This article describes the synthesis and characterization of a variety of new poly(2-oxazoline)s. With regard to functional polymers, 2-oxazolines represent an interesting class of monomers because of the easy variation of the substituent in 2-position. Starting from the corresponding nitriles, different 2-oxazolines were obtained containing a diverse set of 2-substituents, including thioether bonds (M11), trifluoromethyl groups (M8, M10), and alkyl- or aryl groups (M1,M7). The subsequent polymerization of the majority of these monomers proceeded in a living manner, which was demonstrated by linear first-order kinetics, a linear increase of molar mass with conversion, and relatively narrow molar mass distributions. In addition, selected thermal and surface properties of the polymers were studied utilizing DSC and contact-angle measurements to determine the effects of different 2-substituents on the macroscopic properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3829,3838, 2009 [source] Novel organosoluble and colorless poly(ether imide)s based on 3,3-bis[4-(3,4-dicarboxyphenoxy)phenyl]phthalide dianhydride and aromatic bis(ether amine)s bearing pendent trifluoromethyl groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2006Chin-Ping Yang Abstract A novel series of colorless and highly organosoluble poly(ether imide)s were prepared from 3,3-bis[4-(3,4-dicarboxyphenoxy)phenyl]phthalide dianhydride with various fluorinated aromatic bis(ether amine)s via a conventional two-stage process that included ring-opening polyaddition to form the poly(amic acid)s followed by cyclodehydration to produce the polymer films. The poly(ether imide)s showed excellent solubility, with most of them dissoluble at a concentration of 10 wt % in amide polar solvents, in ether-type solvents, and even in chlorinated solvents. Their films had a cutoff wavelength between 358 and 373 nm, and the yellowness index ranged from 3.1 to 9.5. The glass-transition temperatures of the poly(ether imide) series were recorded between 237 and 297 °C, the decomposition temperatures at 10% weight loss were all above 494 °C, and the residue was more than 54% at 800 °C in nitrogen. These films showed high tensile strength and also were characterized by higher solubility, lighter color, and lower dielectric constants and moisture absorption than an analogous nonfluorinated polyimide series. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3140,3152, 2006 [source] Optical and electrochemical properties of copoly(aryl ether)s consisting of alternate 2,5-distyrylbenzene and electron-transporting oxadiazole or triazole derivativesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2005Shinn-Horng Chen Abstract New copoly(aryl ether) P1 consisting of alternate electron-transporting 2-(3-(trifluoromethyl)phenyl)-5-(4-(5-(3-(trifluoromethyl)phenyl)-1,3,4-oxadiazol-2-yl)-2,5-bis(hexyloxy)phenyl)-1,3,4-oxadiazole and hole-transporting 2,5-distyrylbenzene (DSB) was synthesized via nucleophilic substitution polymerization. We investigated the optical and electrochemical properties of alternate copoly(aryl ether)s P1,P6, which contain the same hole-transporting DSB segments, but with different electron transporting segments. The effect of trifluoromethyl groups in electron transporting segments is also discussed. Referencing to the spectra of their model compounds M1,M4, the emissions of P1,P3 are dominated exclusively by the hole-transporting fluorophores with longer emissive wavelength about 452,453 nm via efficient excitation energy transfer. Furthermore, P1,P3 also exhibit unique variations in energy transfer in acidic media and solvatochromism in organic solvents. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of P1,P4, estimated from electrochemical data, are ,5.12, ,5.15, ,5.18, ,5.00 eV and ,2.93, ,3.39, ,3.49, ,2.76 eV, respectively. The electron and hole affinity of P1,P6 can be enhanced simultaneously by introducing isolated hole- and electron-transporting segments in backbone. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5083,5096, 2005 [source] Synthesis of the First Chiral Bidendate Bis(trifluoromethyl)phosphane Ligand through Stabilization of the Bis(trifluoromethyl)phosphanide Anion in the Presence of AcetoneCHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2006Berthold Hoge Priv.-Doz. Abstract Lewis acid/Lewis base adduct formation of the P(CF3)2, ion and acetone leads to a reduced negative hyperconjugation and, therefore, limits the CF bond activation. The resulting increased thermal stability of the P(CF3)2, ion in the presence of acetone allows selective substitutions and enables the synthesis of the first example of a chiral, bidentate bis(trifluoromethyl)phosphane ligand: a DIOP derivative, [(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene)]bis(diphenylphosphane), in which the phenyl groups at the phosphorus atoms are replaced by strong electron-withdrawing trifluoromethyl groups. The resulting high electron-acceptor strength of the synthesized bidentate (CF3)2P ligand is demonstrated by a structural and vibrational study of the corresponding tetracarbonyl,molybdenum complex. The stabilization of the P(CF3)2, ion in the presence of acetone is based on the formation of a dynamic Lewis acid/Lewis base couple, (CF3)2PC(CH3)2O,. Although there is no spectroscopic evidence for the formation of the formulated alcoholate ion, the intermediate formation of (CF3)2PC(CH3)2O, could be proved through the reaction with (CF3)2PP(CF3)2, which yields the novel phosphane,phosphinite ligand (CF3)2PC(CH3)2OP(CF3)2. This ligand readily forms square-planar Pt(II) complexes upon treatment with solid PtCl2. [source] Catalytic Ethylene Polymerisation in Carbon Dioxide as a Reaction Medium with Soluble Nickel(II) CatalystsCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2006Amaia Bastero Dr. Abstract A series of neutral NiII,salicylaldiminato complexes substituted with perfluorooctyl- and trifluoromethyl groups, [Ni{,2 - N,O -6-C(H)NAr-2,4-R,2C6H2O}(Me)(pyridine)] (6,a: Ar=2,6-{4-(F17C8)C6H4}2C6H3, R,=I; 6,b: Ar=2,6-{4-(F3C)C6H4}2C6H3, R,=I; 6,c: Ar=2,6-{3,5-(F3C)2C6H3}2C6H3, R,=3,5-(F3C)2C6H3; 6,d: Ar=2,6-{4-(F17C8)C6H4}2C6H3, R,=3,5-(F3C)2C6H3; 6,e: Ar=2,6-{3,5-(F3C)2C6H3}2C6H3, R,=I) were studied as catalyst precursors for ethylene polymerisation in supercritical CO2. Catalyst precursors 6,a and 6,c, which are soluble in scCO2, afford the highest polymer yields, corresponding to 2×103 turnovers. Semicrystalline polyethylene (Mn typically 104 g,mol,1) is obtained with variable degrees of branching (11 to 24 branches per 1000 carbon atoms, predominantly Me branches) and crystallinities (54 to 21,%), depending on the substitution pattern of the catalyst. [source] The effect of substituents on the aggregation and gelation of azo sulphonate dyesCOLORATION TECHNOLOGY, Issue 3 2005Kunihiro Hamada The aggregation and gelation of sodium 1-phenylazo-2-hydroxy-6-naphthalene sulphonate azo dyes containing fluoro, ethyl, n -propyl, iso -propyl, n -butyl, sec -butyl and tert -butyl groups in the para -position to the azo group have been compared with those containing methyl and trifluoromethyl groups. The behaviour of dyes containing a fluoro group was also studied using 19F NMR spectroscopy. Aqueous solutions of sodium 1-(4- sec -butylphenylazo)-2-hydroxy-6-naphthalene sulphonate at concentrations greater than 0.01 mol dm,3 became gelatinous, whereas the other dyes containing alkyl groups did not show this effect. Although the gelation of aqueous dye solutions of fluorinated dyes has been reported previously, it had not been noticed with dyes containing hydrocarbon chains. Aggregation constants have been determined, and the thermodynamic parameters found to be influenced by chain branching and by the number of carbon atoms present. Important information has been established about the spatial arrangement of fluorine in the aromatic ring. [source] | ||||||||||