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Yaming Niu Xiaoliang Zhu Lingzhi Liu Yan Zhao Zhenhua Jiang 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1459-1467
The new monomer (4‐(4′‐trifluoromethyl)phenoxyphenyl)hydroquinone (TFPOPH) was synthesized in a three‐step synthesis. A series of poly(aryl ether ketone) copolymers were prepared by the reaction of (4‐(4′‐Trifluoromethyl)phenoxyphenyl)hydroquinone and hydroquinone (HQ) with 4,4′‐difluorobenzophenone (DFB) in the presence of potassium carbonate in tretramethylene sulfone (TMS). Thermal analyses of the fluorinated copolymers showed that the glass transition temperature and 5.0% weight loss temperature are similar with that of PEEK, and the crystallinity decreased with increasing of TFPOPH. For the copolymer synthesized with the molar fraction of TFPOPH in the diphenol monomers (TFPOPH, HQ) being over 0.2, no cold crystallization temperature and melting temperature were detected, indicating that these copolymers are almost amorphous. The crystal structure of the copolymers with the molar fraction of TFPOPH being not higher than 0.2 is rhombic. The solubility in polar aprotic solvents of poly(aryl ether ketone)s copolymers increases and dielectric constant decreases step by step. 相似文献
95.
Langang Niu Ramaswamy Nagarajan Dingsong Feng Lynne A. Samuelson 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1983-1990
Main‐chain thermotropic liquid‐crystalline polyesters containing rigid biphenyl mesogens and flexible spacers were synthesized by chemo‐enzymatic route. The enzyme‐catalyzed polymerization showed high regio‐ and chemo‐ selectivity, and is environmentally friendly. The resulting polyesters were characterized with 1H‐NMR, 13C‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and polarized light optical microscopy (POM). 相似文献
96.
Highlights? The complete gougerotin biosynthetic gene cluster is cloned ? Heterologous production of gougerotin is accomplished in S. coelicolor M1146 ? Biosynthetic pathway is proposed based on bioinformatics, genetic, and chemical analyses ? Preliminary data support an uncommon enzymatic reaction for peptide bond formation 相似文献
97.
Seeking visible‐light‐active photocatalysts for efficient solar‐energy conversion has become an intensifying endeavor worldwide. In this concept paper, general requirements for finding new visible‐light‐active photocatalysts are briefly introduced, and recent progress in exploring elemental photocatalysts for clean‐energy generation and environmental remediation are reviewed. Finally, opportunities and challenges facing elemental photocatalysts are discussed. 相似文献
98.
The energies, geometries and harmonic vibrational frequencies of 1:1 5‐hydroxytryptamine‐water (5‐HT‐H2O) complexes are studied at the MP2/6‐311++G(d,p) level. Natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM) analyses and the localized molecular orbital energy decomposition analysis (LMO‐EDA) were performed to explore the nature of the hydrogen‐bonding interactions in these complexes. Various types of hydrogen bonds (H‐bonds) are formed in these 5‐HT‐H2O complexes. The intermolecular C4H55‐HT···Ow H‐bond in HTW3 is strengthened due to the cooperativity, whereas no such cooperativity is found in the other 5‐HT‐H2O complexes. H‐bond in which nitrogen atom of amino in 5‐HT acted as proton donors was stronger than other H‐bonds. Our researches show that the hydrogen bonding interaction plays a vital role on the relative stabilities of 5‐HT‐H2O complexes. 相似文献
99.
Chen Chen Xiangheng Niu Yan Chai Hongli Zhao Minbo Lan Yonggang Zhu Gang Wei 《Electroanalysis》2013,25(6):1446-1452
This work presents a disposable bismuth‐antimony film electrode fabricated on screen‐printed electrode (SPE) substrates for lead(II) determination. This bismuth‐antimony film screen‐printed electrode (Bi‐SbSPE) is simply prepared by simultaneously in situ depositing bismuth(III) and antimony(III) with analytes on the homemade SPE. The Bi‐SbSPE can provide an enhanced electrochemical stripping signal for lead(II) compared to bismuth film screen‐printed electrodes (BiSPE), antimony film screen‐printed electrodes (SbSPE) and bismuth‐antimony film glassy carbon electrodes (Bi‐SbGC). Under optimized conditions, the Bi‐SbSPE exhibits attractive linear responses towards lead(II) with a detection limit of 0.07 µg/L. The Bi‐SbSPE has been demonstrated successfully to detect lead in river water sample. 相似文献
100.
Jiai Hua Xiang Ma Pengtao Ma Jingping Wang Jingyang Niu 《Journal of Cluster Science》2013,24(3):689-700
A new compound H8[NaCu5Cl(H2O)3(B-α-AsW9O33)2] 24H2O (1) is synthetized by the reaction of the CuCl2 2H2O and Na27[NaAs4W40O140] 60H2O in aqueous solution, which is constructed from a {Cu5Na} hexagon moiety sandwiched by two trilacunary [B-α-AsW9O33]9? units. The structure is determined by single-crystal X-ray diffraction technique and further characterized by IR spectroscopy. Single-crystal X-ray diffraction analysis reveals that 1 is built by two trilacunary [B-α-AsW9O33]9? units incorporating a {Cu5Na} hexagon moiety and further linked to each other to form an infinitely extended 2-D network via Cu–O–W bridges. Notably, magnetic measurement demonstrates that the occurrence of intramolecular ferromagnetic Cu–Cu interactions within {Cu5Na} hexagon moiety. 相似文献