Liquid crystal polymers 23. Steric and polar effects of large substituents in thermotropic aromatic polyesters with decamethylene spacers

A series of thermotropic aromatic polyesters based on a triad ester mesogenic unit containing an arylsulfonyl substituted hydroquinone group and a decamethylene spacer group was prepared. The large arylsulfonyl substituent was substituted in the para-position with either electron donating or accepting groups to study the effect of steric and polar interactions on the thermal transitions of these polymers and on the thermodynamic parameters of their isotropization transitions. All polymers formed nematic melts, and a regular decrease in T₁, ΔH₁ and ΔS₁ was observed with increasing molecular radius of the substituted hydroquinone group. However, a polarity or polarizability effect was superimposed on these relationships. Model compounds containing the same aromatic ester triad were prepared and their thermotropic properties were compared to those of the polymers. Essentially identical effects were observed for both.     

Halogenation of N-substituted <Emphasis Type="Italic">p</Emphasis>-quinone monoimines and <Emphasis Type="Italic">p</Emphasis>-quinone monooxime esters: VII. Halogenation of 4-aroyl(arylsulfonyl)imino- and 4-aroyl(arylsulfonyl)-oxyimino-2,6-diisopropylcyclohexa-2,5-dien-1-ones

Halogenation of 4-aroyl(arylsulfonyl)imino-2,6-diisopropylcyclohexa-2,5-dien-1-ones gave 4-aroyl-(arylsulfonyl)imino-3-halo-2,6-diisopropylcyclohexa-2,5-dien-1-ones and 4-aroyl(arylsulfonyl)imino-3,5,6-trihalo-2,6-diisopropylcyclohex-2-en-1-ones. The latter were formed as mixtures of two stereoisomers, and the isopropyl group on the sp ³-hybridized carbon atom in one stereoisomer occupies axial position, which is untypical of such compounds. Halogenation of 4-aroyl(arylsulfonyl)oxyimino-2,6-diisopropylcyclohexa-2,5-dien-1-ones leads to the formation of the corresponding addition products with traditional trans-diaxial arrangement of the halogen atoms.     

Biphilic properties of substituted triphenylphosphoranylideneacetonitriles bearing 4,5-Di(arylsulfonyl)-1,3-thiazol-2-yl fragments at the ylide center

Phosphonium ylides stabilized by nitrile and 4,5-di(arylsulfonyl)-1,3-thiazol-2-yl fragments show biphilic reactivity. They react with aromatic aldehydes upon heating revealing a noticeable activity of ylide center and are condensed with typical nucleophiles at C⁴ center of the thiazole ring with the elimination of arylsulfonyl group under mild conditions. New 1,3-thiazole derivatives were obtained whose structures were proved by chemical, spectal and X-ray structural investigations.     

Halogenation of N-Substituted p-Quinonimines and p-Quinone Oxime Esters: II. Chlorination and Bromination of 4-Aroyl(arylsulfonyl)oxyimino-2-methyl-2,5-cyclohexadienones

Halogenation of 4-aroyl(arylsulfonyl)oxyimino-2-methyl-2,5-cyclohexadienones yields Z,E-isomeric 4-aroyl(arylsulfonyl)oxyimino-5,6-dihalo-2-methyl-2-cyclohexenones and (E)-4-aroyl(arylsulfonyl)oxyimino-5,6-dihalo-6-methyl-2-cyclohexenones. Further chlorination leads to formation of (Z,E)-4-aroyl(arylsulfonyl)oxyimino-2,5,6-trichloro-6-methyl-2-cyclohexenones.     

荧光聚合物研究进展

本文总结了近年来荧光聚合物的研究进展,主要介绍了荧光聚合物的分类：按其溶解性能可分为非水溶性、水溶性和两亲荧光聚合物三大类;荧光聚合物的合成：荧光化合物为引发剂、荧光化合物为链转移剂、荧光功能单体聚合、荧光化合物与聚合物的化学键合、非荧光功能单体聚合等五种制备荧光聚合物的设计合成方法;荧光聚合物的应用：荧光聚合物在荧光化学传感器、荧光分子温度计、荧光造影、药物载体、荧光探针等方面的应用研究。     

氨基氮杂环荧光分子改性苯乙烯马来酸酐共聚物的研究

荧光高分子材料 ,由于其独特光学性质 ,成为功能高分子研究热点[1～ 3 ] .一般而言 ,荧光聚合物的合成有两种方法 ,一是首先合成荧光单体 ,然后与其他适宜单体聚合 ,得到荧光聚合物 ,然而荧光单体结构复杂 ,提纯困难 ,难以获得高分子量、成膜性能好的聚合物[4] ;另一种方法是通过官能团的反应 ,用荧光物质对聚合物进行化学改性来制备[5,6] .苯乙烯 马来酸酐共聚物 (ＳＭＡ)是一类成本低廉 ,性能良好的商品化聚合物材料 ,主链中含有具有反应性能的酸酐基团 ,这就使通过化学改性制备荧光聚合物成为可能 .本文通过 2 氨基苯并咪唑 ( 1 ) ,4 …     

2-烷基-2-(芳磺酰基)乙酸酯的高效共轭加成

本文报道在固-液相转移催化的温和条件下2-烷基-2-(芳磺酰基)乙酸酯(1)与α, β-不饱和酯、腈、酮(2)的高选择性和高效率共轭加成反应。成功地合成了2, 2-二取代戊二酸二酯(3a~d)、4-氰基丁酸酯(3e~g)和5-氧代己酸酯(3h~j)。对它们的结构作了表征。初步讨论了本合成法的特点。Michael受体、相转移催化剂和溶剂等对共轭加成反应的影响。     

苯乙烯马来酸酐共聚物(SMA)化学改性制备荧光聚合物及其荧光性能研究

用自行合成的 2-氨基噻唑 (1)、2-氨基-4-苯基噻唑 (2)、2-氨基苯并噻唑(3)等荧光小分子化合物,与商品化的苯乙烯马来酸酐共聚物 (SMA)中的酸酐基团反应,制成聚苯乙烯马来酰亚胺 (SMI),实现了SMA化学改性.在获得荧光聚合物的同时,不仅保持了原SMA的可溶性、成膜性等优点,其热性能也得到了改善.通过示差扫描量热 (DSC)、凝胶色谱 (GPC)、红外、紫外及荧光光谱等手段表征了荧光聚合物的玻璃化转变温度、分子量及结构与荧光性能关系.     

Regioselective synthesis of (E)-3-[2-(arylmethylene)-1-(arylsulfonyl)hydrazino]-2-propenoates via the reaction of arylsulfonyl hydrazones and alkyl propiolates in the presence of triphenylphosphine

A regioselective method for the synthesis of (E)-3-[2-(arylmethylene)-1-(arylsulfonyl)hydrazino]-2-propenoates is described. The reaction takes place between arylsulfonyl hydrazones and alkyl propiolates in the presence of triphenylphosphine as the catalyst.     

Facile domino reactions in the statistically controlled product- and stereoselective synthesis of densely functionalized cis-1,4-cyclohexa-1,4-dienes and trans,trans-trisubstituted-1,2,5,6-tetrahydropyridines

The domino reactions of ethyl 3-oxo-4-(arylsulfonyl)butanoates with aromatic aldehydes in a 2:1 molar ratio in the presence of a catalytic amount of ammonium acetate furnished densely functionalized cyclohexa-1,4-dienes stereoselectively, while the domino reactions of ethyl 3-oxo-4-(arylsulfonyl)butanoates, aromatic aldehydes, and ammonium acetate in a 1:2:2 molar ratio afforded highly functionalized 1,2,5,6-tetrahydropyridines stereoselectively.     

Novel fluorescent amphiphilic poly(allylamine) and their supramacromolecular self‐assemblies in aqueous media

Fluorescent amphiphilic polymers were produced by grafting different types and levels of hydrophobic pendant groups with intrinsic fluorescent properties (fluorenylmethoxy carbonyl (Fmoc), dimethylamino‐1‐naphthalenesulfonyl (Dansyl), and naphthalene (Naphth) to a water soluble homopolymer backbone, polyallylamine (PAA). Non‐fluorescent hydrophobic pendant group (cholesteryl moieties) were also grafted onto PAA. The polymers were characterized with elemental analysis, NMR and FTIR spectroscopy. All polymers formed self‐assemblies by probe sonication in water with sizes ranging from 120 to 199 nm and TEM images showed the presence of spherical particles. The critical aggregation concentration (CAC) varied from 0.093 to 1.5 mg ml^?1 depending on the type of hydrophobic pendant groups. The Cholesteryl and Dansyl polymers showed the presence of one CAC while the Fmoc and Naphth grafted polymers revealed the presence of two CACs. The first CAC observed was possibly due to intermolecular aggregation while the second CAC at the higher polymer concentration was the result of excimer formation revealed by their fluorescent spectra. We reasoned that Naphth and Fmoc aromatic pendant groups possess a flat stereochemistry, thus allowing π–π stacking at higher concentrations. The presence of the N‐dimethylamino group in the Dansyl moiety gives rise to a 3D structure, thus hindering any stacking. The understanding of the supramolecular assemblies formed by these fluorescent amphiphilic polymers will aid in the engineering of advanced materials with superior functionality for biomedical applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Addition-Rearrangement of Aryl- and Alkoxysulfonyl Isocyanates with 5-Methyl-Substituted 3,4-Dihydro-2-methoxy-2H-pyrans. Selective Synthesis of Functionalized 2-Piperidones(1)

3,4-Dihydro-2-methoxy-5-methyl-2H-pyran and 3,4-dihydro-2-methoxy-5,6-dimethyl-2H-pyran undergo addition-rearrangement reactions with arylsulfonyl isocyanates to generate the corresponding 3-formyl- and 3-acetyl-6-methoxy-3-methyl-1-(arylsulfonyl)-2-piperidones. For example, 3,4-dihydro-2-methoxy-5-methyl-2H-pyran and phenylsulfonyl isocyanate afforded 3-formyl-6-methoxy-3-methyl-1-(phenylsulfonyl)-2-piperidone as a separable trans/cis mixture in high yield. The more reactive phenoxysulfonyl and alkoxysulfonyl isocyanates provided analogous results.     

Redox-triggered hydroarylation of o-(hydroxyalkyl)arylalkynes with arylsulfonyl chlorides using visible light catalysis

A new radical-mediated method for the synthesis of 1-(2-(1,2-diarylvinyl)phenyl)ethan-1-ones by the redox hydroarylation of o-(hydroxyalkyl)arylalkynes with arylsulfonyl chlorides is described. This visible light catalysis method proceeds via a sequence of the radical addition of aryl group across the C-C triple bond, protonation and redox reaction, and represents a new redox transformation reaction directed by a neighboring hydroxyl group.     

Synthesis of 2-Substituted Benzimidazoles, Benzoxazoles, and Benzothiazoles from Arylsulfonyl(thio)propionitriles

The reaction of nitriles and of methyl imino ester hydrochlorides of arylsulfonyl(thio)propionic acids with o-phenylenediamine, o-aminophenol, and o-aminothiophenol has been studied. A series of new 2-substituted benzazoles has been synthesized containing arylsulfonyl(thio)propionic acid fragments.     

Synthesis of indolylalkylphosphonates and 3-(1-diphenylphosphinoalkyl) indoles by reaction of 3-(1-arylsulfonylalkyl) indoles with phosphorus derivatives

Dialkyl phosphites as well as diphenylphosphine react with 3-(1-arylsulfonylalkyl) indoles under basic conditions leading to a formal substitution of the arylsulfonyl group through a reactive 3-alkylidene indole intermediate.     

基于四唑功能位点的Tb~(3+)配位聚合物的构筑及其金属离子荧光检测性能

镧系金属配位聚合物因其独特的组成、结构和性质被广泛应用于荧光识别检测性质研究,但其功能导向构筑依然具有挑战性。本文基于双功能基团配体构筑策略构筑了一例Tb~(3+)配位聚合物[Tb(TZI)(DMF)_2(H_2O)]·(H_2O)(1)((H_3TZI=5-(1-氢-5-四唑基)间苯二甲酸,DMF=N,N-二甲基甲酰胺)),在对其进行详细结构表征的基础上研究了其金属离子识别检测性质。结果表明,基于羧酸和四唑基团与Tb~(3+)离子配位能力的不同,在确保Tb~(3+)配位聚合物成功构筑的同时可将四唑作为识别位点引入配位聚合物框架,使得配合物1可展现出基于金属离子与四唑功能位点配位导致的荧光增强,可实现对Zn~(2+)和Na~+离子的识别检测。本文所报道的结果可为镧系金属配位聚合物的荧光识别检测性质导向构筑提供有价值的参考。     

Desulfinative palladium‐catalyzed cross‐coupling of arylsulfonyl hydrazides with aryl bromides under air

A highly efficient and mild palladium‐catalyzed cross‐coupling of arylsulfonyl hydrazides and aryl bromides for the selective synthesis of unsymmetrical biaryls has been developed. This methodology has the advantages of easily accessible starting materials, functional group tolerance and a wide range of substrates, which provide rapid access to biaryls derivatives. In this protocol, abundant and stable aryl bromides serve as the aryl sources by coupling reaction of the aryl group generated from arylsulfonyl hydrazides via in situ release of nitrogen and sulfur dioxide. No external oxidants or acids are needed for this kind of transformation.     

Direct polycondensation of aromatic dicarboxylic acids and bisphenols with tosyl chloride and N,N-dimethylformamide in pyridine

A Vilsmeier adduct derived from arylsulfonyl chlorides and DMF in pyridine was successfully used as a new condensating agent for the synthesis of aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols and also of hydroxybenzoic acids. Polymers of high molecular weights (M?_w = 78,000) with relatively narrow molecular weight distribution (M?_w/M?_n ≈ 3.0) were prepared by reacting aromatic dicarboxylic acids with the adduct in pyridine, followed by addition of bisphenols. The polycondensation was significantly affected by the amount of DMF, the nature of the arylsulfonyl chlorides, the conditions of initial reaction of the acids with the adduct, and the rate of reaction with bisphenols. The process was adaptable to the direct polycondensation of hydroxybenzoic acids, affording polymers of high molecular weight (η_inh = 1.73).     

Synthetic Applications of π-Electron-Deficient Sulfones

Abstract

The use of π-electron-deficient aryl sulfones, especially 3,5-bis(trifluoromethyl) phenyl alkyl sulfones (BTFP-sulfones) as soft nucleophiles, as caboxylic acid protecting group and in Julia–Kocienski olefination reactions is described. In the case of α-(arylsulfonyl)acetates dialkylation, reactions are performed under phase-transfer analysis (PTC) conditions using K ₂ CO ₃ as base. Esters derived from 2-(arylsulfonyl)ethanol can be deprotected using aqueous NaHCO ₃ . Alkyl BTFP sulfones are coupled with carbonyl compounds using KOH or P4-t-Bu as bases to give the corresponding alkenes after Smiles rearrangement.     

Synthesis of poly(vinyl acetate) with fluorescence via a combination of RAFT/MADIX and “click” chemistry

A novel ω-azido-functionalized RAFT reagent, O-(2-azido-ethyl) S-benzyl dithiocarbonate (AEBDC), was synthesized and subsequently employed to mediate the reversible addition-fragmentation chain transfer (RAFT) polymerization of vinyl acetate (VAc) to prepare end-functionalized polymers. The polymerization results showed that the RAFT polymerizations of VAc could be well controlled using AEBDC as the RAFT agent. Number-average molecular weights (M_n GPC) increased linearly with monomer conversion, and molecular weight distributions were relatively narrow. ¹H NMR spectrum of the poly(vinyl acetate) (PVAc) confirmed the existence of functional azido group at the end of the polymers chains. The ω-azido-terminated polymers were coupled by “click” chemistry with a fluorescent alkyne, 7-propinyloxy coumarin, to prepare fluorescent PVAc. The fluorescence properties of the PVAc homopolymers before and after coupling with 7-propinyloxy coumarin in CH₂Cl₂ solution were investigated.