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121.
Ivan S. Alferiev Narendra R. Vyavahare Cunxian X. Song Robert. J. Levy 《Journal of polymer science. Part A, Polymer chemistry》2001,39(1):105-116
Three types of elastomeric segmented polyurethanes represented by a polyether‐urethane, a polyurethane‐urea, and a polycarbonate‐urethane were introduced into a modified low‐temperature variant of base‐induced N‐alkylation of urethane hard segments with an excess of 1,6‐dibromohexane in N,N′‐dimethylacetamide (DMAc), resulting in the modification of polymers with 0.08–0.26 mmol/g of pendant 6‐bromohexyl groups. Either lithium diisopropylamide (LDA) or sodium hydride was used to initiate the reaction, although LDA was found to be more suitable for the bromoalkylation. Selected bromoalkylated polyurethanes of all three types were reacted with thiol‐containing bisphosphonates, to yield the polymers modified with 0.08–0.12 mmol/g of geminal nonesterified covalently attached bisphosphonate groups. Two thiol‐containing geminal bisphosphonates used in the modifications were prepared via reactions of nucleophilic addition to vinylidene‐bisphosphonic acid. All three types of polyurethanes were found equally suitable for the modifications. The bisphosphonate‐modified polyurethanes with nonmetallic cations on the bisphosphonate groups remain soluble in the solvents suitable for the dissolution of nonmodified polymers and can be processed into films by solvent casting. After the exchange of nonmetallic cations to sodium, the polymers become insoluble in any solvent, probably as a result of the intermolecular coordination of bisphosphonate groups with the metal cations. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 105–116, 2001 相似文献
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利用实验观测与密度泛函理论(DFT)计算方法考察了新化合物N, N'-二-[3-羟基-4-(2-苯并噻唑)苯基]脲(4-DHBTU)的红外、核磁与紫外吸收光谱性质.与单体2-(4-氨基-2-羟苯基)苯并噻唑(4-AHBT)相比, 4-DHBTU的实验紫外吸收强度显著增强,最大吸收峰发生了明显红移,并呈现出双吸收峰特征.结合实验光谱数据与密度泛函理论计算分析表明, 4-DHBTU分子最稳定的基态异构体为cis-C11和trans-C11,而导致上述紫外光谱差异的主要原因是4-DHBTU样品中cis-C11, trans-C11, cis-C22, trans-C22等多种异构体共存.此外, 4-DHBTU与溶剂二甲基亚砜(DMSO)间氢键作用使得核磁实验中4-DHBTU的15H、16H氢谱化学位移显著增大. 相似文献
124.
A series of 6,7-dimethoxyquinazoline derivatives connected by diaryl urea scaffolds was designed, synthesized and their in vitro antitumor activities were evaluated. Most of them showed an excellent potency against the four tested cancer cell lines as compared with sorafenib. Particularly, a promising compound 20 was identified, which showed the most potent antitumor activities with IC50 values of 0.08, 0.09, 0.16 and 0.19 μmol/L against H460, HT-29, MKN-45 and MDA-MB-231 cell lines, respectively. The structure-activity relationship(SAR) analysis indicated that compounds with dimethylamino or diethylamino group at the C4 position of 6,7-dimethoxyquinazoline moiety exhibited superior activities than compounds bearing morpholino groups. 相似文献
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An efficient synthesis of benzoxazole-substituted 3,4-dihydropyrimidinones(DHPMs) using trifluoro acetic acid as the catalyst for the first time from an aldehyde,β-keto ester and benzoxazole-substituted urea/thiourea under solvent-free conditions is described.Compared to the classical Biginelli reaction conditions,this new method consistently has the advantage of excellent yields(80-91%) and short reaction time(40-130 min) at reflux temperature. 相似文献
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Silicone‐urethane membranes for lithium batteries. Part 1. Moisture‐cured poly(siloxane‐urethane‐urea) elastomers containing polyethylene oxide (PEO) segments – synthesis and characterization as potential membrane materials
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Poly(siloxane‐urethane‐urea) elastomers containing both polysiloxane and polyethylene oxide (PEO) segments in the polymer chain were obtained by moisture‐curing of NCO‐terminated poly(siloxane‐urethane) prepolymers synthesized from isophorone diisocyanate and mixtures of polyoxyethylene diols and polysiloxane diols with various molecular weights. Mechanical properties of the moisture‐cured films and their swelling ability in solvent mixtures commonly used in lithium batteries were investigated, and it was found that they were greatly influenced by PEO content in the polymer. PEO content in the polymer was also found to affect very much the electric conductivity of the films after immersion in lithium salt solution in ethylene carbonate–dimethyl carbonate solvent mixture. At high contents of PEO in the polymer chain specific conductivities of the films in a range of 10?3, Scm?1 could be achieved at room temperature. Based on the results of Scanning Electron Microscopy with X‐ray Analysis (SEM/EDS) investigations and wide‐angle X‐ray scattering and small‐angle X‐ray scattering studies, it could be anticipated that the reason for good conductivity of the films might be their specific supramolecular structure that potentially facilitated lithium ion mobility. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
130.
Gudipati Srinivasa Rao Srinivas Basavoju 《Molecular Crystals and Liquid Crystals》2014,605(1):225-239
A novel Betti base compound, 1-((2-hydroxynaphthalen-1-yl)(2-hydroxyphenyl)methyl)urea, UBB, was synthesized and characterized by spectral, structural and thermal studies. Single crystal X-ray diffraction studies reveal that the racemic mixture of the compound, when crystallized from DMF, yields R-isomer preferentially (prismatic crystals), whereas, when crystallized from 5:1 (v/v) mixture of DMF-THF, it yields S-isomer (rectangular shaped crystals) with two molecules of DMF, included in both the cases. The crystal structure is discussed in terms of supramolecular interactions and molecular modeling. Both R and S enantiomeric DMF solvate crystals are in their chiral triclinic P1 space group. 相似文献