谷氨酸低分子量有机凝胶的药物控制释放行为

低分子量的有机胶凝剂组装形成的有机凝胶可应用于药物缓释体系.本研究中,使用亲水的钙黄绿素和疏水的布洛芬为模型分子,研究其在谷氨酸衍生物有机凝胶体系中的缓释行为.研究表明,与药物分子与有机胶凝剂简单混合的体系相比,亲水或疏水的药物分子在有机凝胶体系中的释放速度显著减缓.SEM的研究发现药物粒子嵌入在有机凝胶的三维网络中,因此,有机凝胶的三维网络结构可认为是实现药物缓慢释放的基质,药物分子从网络中的释放受限导致了其从有机凝胶中的缓释行为.     

酰肼衍生物的凝胶化行为

N,N-(5-烷氧基-1,3-苯二甲酰)-N',N'-二(4-甲基苯甲酰)二肼系列化合物(An)能在苯、甲苯、硝基苯及氯仿等有机溶液中形成有机凝胶. X射线衍射实验及扫描电子显微镜观察的结果显示, 在凝胶状态下, An分子聚集成层状有序排列, 并进一步堆积形成纤维网络结构. 红外光谱及核磁氢谱研究证实了分子间氢键码酰肼衍生物形成凝胶的驱动力. 另外, 侧链上烷基链的长度对凝胶的能力及凝胶的稳定性影响较大, 而对于凝胶的形貌及分子聚集的结构影响不大.     

有机低分子凝胶因子

糖苷、甾核、氨基酸等类型结构化合物是近年来有机低分子凝胶因子的研究重点,联（并）苯、有机金属化合物以及二元凝胶体系等方面有了新的拓展。本文综述了2000年以来有机低分子凝胶因子主要结构类型、表征方法和应用的研究进展,分析了凝胶因子在敏感性材料、无机纳米材料、固体燃料、固体电解质、药物控释等方面的应用,展望了其在分子识别、光电材料、半导体材料、生物催化等方面的潜在应用。     

反应型凝胶剂2,4-二烷脲基甲苯衍生物及有机溶剂的室温凝胶化研究

通常制备有机分子凝胶是在高温下溶解凝胶剂,凝胶剂分子在冷却过程中进行自组装并使有机溶剂凝胶化.该方法限制了某些低沸点溶剂的凝胶化.利用甲苯二异氰酸酯与烷基胺的高反应活性,制备了3种反应型凝胶剂.这种反应型凝胶剂能以较低的浓度在室温下使某些芳香族和卤代烃溶剂形成热可逆的有机分子凝胶.场发射扫描电镜表明这种反应型凝胶剂在有机溶剂中自组装形成纤维状三维网络结构.随着烷基胺中的烷基链长度不同,形成的纤维状聚集体的形态也不同.FT-IR和1H NMR研究表明分子间氢键作用是反应型凝胶剂自组装的驱动力.通过XRD和分子模拟推测了其聚集体的结构形态.     

π-共轭三苯基苯衍生物的合成及其胶凝性能

合成了一系列三单脂肪链具有盘状结构的三苯基苯衍生物并研究了其在有机溶剂中自组装行为. 结果表明, 该系列衍生物在多种低极性有机溶剂中可以形成稳定的凝胶, 利用小角X射线衍射实验和扫描电子显微镜技术观察到干凝胶的分子排列具有层状结构, 形成纤维状和片层状聚集, 紫外-可见吸收光谱和红外光谱结果表明分子间氢键和π-π共轭堆积效应是形成自组装凝胶的主要驱动力. 在形成凝胶过程中, 凝胶剂分子在溶液中通过盘状中心的π-π共轭堆积效应和酰胺键的分子间氢键作用自组装成层状结构, 层状结构进一步组装形成纤维状和片层状聚集体, 最终形成三维网状结构阻碍溶剂流动形成凝胶.     

L-苯丙氨酸衍生物与脂肪胺构筑双组分超分子凝胶

设计合成了系列单链L-苯丙氨酸衍生物,该系列衍生物单组分没有胶凝性能.选择脂肪胺作为配对物,与L-苯丙氨酸衍生物组成双组分体系后能够胶凝许多有机溶剂形成凝胶.流变学测试显示该凝胶体系弹性模量(G′)比粘性模量(G′′)约高一个数量级,有着很好的机械性能,并且呈现出典型的类固体的流变学行为.傅里叶变换红外(FT-IR)光谱、核磁共振(NMR)谱、小角X射线衍射(SAXS)和扫描电镜(SEM)结果表明,凝胶中胶凝剂分子形成纤维状或片层状的聚集体,羧基(―COOH)和氨基(―NH2)的酸碱作用、酰胺基团间(―CONH―)的氢键作用以及分子间范德华作用力是形成该凝胶的主要驱动力.凝胶中胶凝剂分子自组装形成具有周期性的层状有序结构,层状结构进一步组装形成纤维状聚集体,最终形成三维网状结构阻碍溶剂流动形成凝胶.     

亚苄基山梨醇衍生物在有机溶剂中的自组装及凝胶化研究

从分子结构的差异、亲溶剂作用、分子几何构型、相转变热焓以及溶剂极性等方面研究了三种亚苄基山梨醇衍生物凝胶剂在有机溶剂中的自组装和凝胶化机理. 三种衍生物凝胶剂在结构上的差别仅在于亚苄基上甲基取代基数量不同. 结果表明: 由于亲溶剂作用的增加和分子几何构型的优化, 含甲基多的凝胶剂在有机溶剂中的自组装能力强, 表现在具有低的最低凝胶化浓度和高的相转变温度. 而溶剂极性的增强, 使三种衍生物凝胶剂形成的凝胶相转变温度降低. 偏光显微镜照片表明该凝胶剂在正辛醇凝胶中的聚集体晶型不同. 场发射扫描电镜照片表明三种衍生物凝胶剂自组装形成相互缠绕的纤维束网络结构. 紫外吸收光谱表明, 对比其溶液态, 三种衍生物聚集体苯环的K带发生红移, 表明π-π堆积作用是亚苄基山梨醇衍生物凝胶剂自组装的驱动力之一; 红移的幅度随苯环上甲基数量的增加而增加, 这与三种衍生物形成的分子凝胶的热稳定性相吻合.     

L-苯丙氨酸衍生物与脂肪胺构筑双组分超分子凝胶

设计合成了系列单链L-苯丙氨酸衍生物,该系列衍生物单组分没有胶凝性能. 选择脂肪胺作为配对物,与L-苯丙氨酸衍生物组成双组分体系后能够胶凝许多有机溶剂形成凝胶. 流变学测试显示该凝胶体系弹性模量（G’）比粘性模量（G"）约高一个数量级,有着很好的机械性能,并且呈现出典型的类固体的流变学行为. 傅里叶变换红外（FT-IR）光谱、核磁共振（NMR）谱、小角X射线衍射（SAXS）和扫描电镜（SEM）结果表明,凝胶中胶凝剂分子形成纤维状或片层状的聚集体,羧基（―COOH）和氨基（―NH₂）的酸碱作用、酰胺基团间（―CONH―）的氢键作用以及分子间范德华作用力是形成该凝胶的主要驱动力. 凝胶中胶凝剂分子自组装形成具有周期性的层状有序结构,层状结构进一步组装形成纤维状聚集体,最终形成三维网状结构阻碍溶剂流动形成凝胶.     

胆酸超分子凝胶化学

胆酸来源丰富,价格低廉,在生命过程中发挥着重要的作用。与胆固醇不同,胆酸以其结构和修饰途径的多样性,以及独特的双亲结构备受超分子化学工作者关注。近年来以胆酸为基本构筑单元的小分子胶凝剂创制及其相关凝胶的研究取得了重要的进展。本文从胆酸衍生物结构设计到胆酸衍生物凝胶构建,概要介绍了胆酸超分子凝胶及其性能研究进展。在此基础上,简要阐述胆酸超分子凝胶材料的潜在应用。     

有机凝胶自组装模板法制备纳米材料

利用溶胶一凝胶聚合过程人工模拟生物矿化进程的技术,已经融人无机材料和超分子有机化学的研究领域.小分子有机凝胶因子在溶剂中发牛自组装,形成多种形态的有机凝胶超分子结构,以其为模板,经过溶胶一凝胶过程,可以诱导转录形成各种形态的纳米材料.本文介绍了利用有机凝胶因子自组装结构为模板制备形态可控无机材料的研究进展及模板结构诱导转录的两种可能机制.     

Amino acid derivatives of cholesterol as "latent" organogelators with hydrogen chloride as a protonation reagent

A series of low molecular weight organic gelator (LMOG) gel systems sensitive to alkaline/acidic stimuli was established by employing amino acid derivatives of cholesterol as "latent" gelators, which are cholesteryl glycinate (1), cholesteryl L-alaninate, cholesteryl D-alaninate, cholesteryl L-phenyl alaninate, and cholesteryl D-phenyl alaninate. The hydrochloric salts are denoted as 2, 3, 4, 5, and 6, respectively. For the 18 solvents tested, one proved to be a weak gelator and gels only two of the solvents. Its gelation ability, however, was greatly improved by bubbling HCl gas, which was produced by reaction of concentrated sulfuric acid with NaCl, through its solution owing to protonation of its amino group. It was demonstrated that the protonated form of it gelled 14 of the solvents tested. Further investigation revealed that the gels changed into solution with addition of any of the amines, including triethylamine (TEA), diethylamine, ethylenediamine, and NH3. The phase transition could be reversed by further introduction of the acidic gas. SEM measurements showed that 1 self-assembled into different supramolecular structures in different gels. Salt effect studies proved that electrostatic interaction is one of the driving forces for formation of the gels.     

Effect of the structure of gelators on electro-optical properties of liquid crystal physical gels

Low molecular mass organic gelator (LMOG) as an important component of liquid crystal physical gel has a great influence on the electro-optical properties. In this paper, three analogues of amide gelator were synthesized and employed as LMOGs in nematic liquid crystal 5CB. Both hydrogen-bonding and pi-pi-stacking interactions in the gel phase were found to stabilize the self-assembled structure. It was observed that the morphology was highly dependent on the crystallinity of gelators, which was affected by the intensity of hydrogen bonding. The thicker fibril was obtained with higher crystallinity of LMOG, while the thinner fibril was obtained with lower crystallinity. Moreover, the electro-optical properties of liquid crystal physical gels were proposed to be related to the interaction between the fibrils and the liquid crystal molecules.     

刺激响应型有机小分子凝胶的研究进展

智能型凝胶是近年来有机小分子凝胶的研究重点, 其中刺激响应型有机小分子智能凝胶对外界微小的物理、化学刺激, 如温度、光、pH、离子强度或电场等能够感知并在响应过程中有显著的响应行为性. 较系统地综述了刺激响应型有机小分子智能凝胶的结构特点和近年来的研究进展, 并展望了该类有机小分子智能凝胶的应用前景.     

Gelation of perfluorinated liquids by N-alkyl perfluoroalkanamides

Gels comprised of low-molecular-mass organic gelators (LMOGs), N-alkyl perfluoroalkanamides [F(CF2)(m)CONH(CH2)(n)H; FmNHn], and several perfluorinated liquids are described. The gelation ability of the amides has been compared to that of two analogous alkyl perfluoroalkanoates. The properties of these gels have been correlated with the N-alkyl and (to a lesser extent) perfluoroalkyl chain lengths in the FmNHn by X-ray diffraction, polarizing optical microscopy, infrared spectroscopy, and small-angle neutron scattering. The gels are thermally reversible and require generally very low concentrations (<2 wt %) of LMOG. Several of the gels have been stable at room temperature for >1 year, thus far. The incompatibility of the fluorocarbon and hydrocarbon segments causes the LMOGs to aggregate into lamellae within the fibrils that constitute the basic unit of the gel networks. IR spectroscopic studies of these gels indicate that additional ordering within the aggregate units is enforced by intermolecular H-bonding among amide groups.     

Effect of Alkyl Chain Length of N-Alkyl-N′-(2-benzylphenyl)ureas on Gelation

Urea derivatives that were substituted with a 2-benzylphenyl group and an alkyl group functioned as low molecular weight gelators for various organic solvents and ionic liquids. Urea derivatives with long alkyl chains were effective for the gelation of polar solvents. However, they were not suitable for the gelation of non-polar solvents, whereas urea derivatives with short alkyl chains were effective. Ionic liquids were similar to polar solvents in that urea derivatives with long alkyl chains were the most effective gelators. The physical properties of the formed supramolecular gels were analyzed by dynamic viscoelasticity measurements using a rheometer.     

Novel deoxycholic acid alkylamide-phenylurea-derived organogelators

Three monomeric and three dimeric deoxycholic acid (DCA) alkylamido-phenylurea derivatives are designed based on known gelators and are synthesized and characterized by ¹H and ¹³C NMR spectroscopy, ESI-TOF mass spectrometry, and elemental analyses. Among them, a monomeric derivative forms supramolecular gels in CHCl₃ and chlorobenzene, whereas a dimeric derivative gels THF and higher 1-alkanols containing 7-10 carbons. The morphologies of their xerogels are studied by scanning electron microscopy (SEM). No signature of macroscopic chirality of the gels is visible.     

Cyclohexane-based low molecular weight hydrogelators: a chirality investigation

Seven new 1,3,5-cyclohexyltricarboxamide-phenylalanine derivatives were synthesized in order to investigate the effect of the amino acid chirality on the gelating properties of these small molecules in water. Gelation tests have shown that enantiomerically pure homochiral 1,3,5-cyclohexyltricarboxamide-L-phenylalanine is a non-hydrogelator as it crystallizes from water, whereas the heterochiral derivatives with either two L-phenylalanine moieties and one D-phenylalanine (LLD), or vice versa (DDL), are very good hydrogelators. Concentration-dependent gel-to-sol transition-temperature (T(gs)) curves for LLD or DDL gels show a sigmoidal behaviour, which is in contrast to the logarithmic curves generally observed for gels derived from low molecular weight gelators (LMWGs). Such sigmoidal behaviour can be related to interactions between fibre bundles, which give rise to intertwined bundles of fibres. Transmission electron microscopy (TEM) images of LLD and DDL gels show a network of thin, unbranched, fibre bundles with diameters of 20 nm. Right-handed twisted fibre bundles are present in the LLD gel, whereas left-handed structures can be found in the DDL gel. Each bundle of fibres consists of a finite number of primary fibres. Gels consisting of mixtures of gelators, LLD and DDL, and nongelators (LLL or DDD) were investigated by means of T(gs) measurements, CD spectroscopy and TEM. Results show that the incorporation of nongelator molecules into gel fibres occurs; this leads to higher T(gs) values and to changes in the helicity of the fibre bundles. Furthermore, it was found that peripheral functionalization of the homochiral derivatives LLL or DDD by means of a second amino acid or a hydrophilic moiety can overcome the effect of chirality; this process in turn leads to good hydrogelators.     

Design, synthesis and stimuli responsive gelation of novel stigmasterol-amino acid conjugates

An efficient synthesis of three novel stigmasterol-amino acid (glycine, L-leucine and L-phenylalanine) conjugates as stimuli responsive gelators is reported. The gelation properties of the prepared compounds were investigated in a variety of organic as well as aqueous solvents. The most striking finding of our investigation was that the hydrochloride salts of the prepared conjugates acted as gelators, whereas the neutral conjugates were either non-gelators or formed only a weak gel in anisole. The hydrochloride salts of stigmasteryl glycinate and L-leucinate form gels in n-alcohols (n=4-10) and in ethane-1,2-diol, and that of stigmasteryl L-phenylalaninate forms gels in aromatic solvents and in tetrachloromethane. These unique properties of the gelators were explored to prepare stimuli responsive, "acid-base" triggered reversible sol-gel transitions. The gelators and their gels were characterized by liquid and solid-state NMR as well as FT-IR. The morphology of their corresponding xerogels was investigated by SEM.