氨基酸修饰β-环糊精对胆酸分子键合的热力学性质及生物应用

环糊精对客体分子的选择键合是当今超分子化学的研究热点之一.其中,环糊精衍生物对胆酸类分子的键合行为及热力学性质研究对于理解主-客体识别机理及热力学起源具有重要的科学意义.本文主要综述了甘氨基、色氨酸、酪氨酸及其脱羧衍生物修饰的β-环糊精对几种典型胆酸分子的识别,包括胆酸(CA)、脱氧胆酸(DCA)、鹅去氧胆酸(CDCA)、甘胆酸(GCA)及牛黄胆酸(TCA)的键合模式、键合能力、分子选择性以及热力学起源,尤其是在清除体内胆酸、调控胆酸平衡、治疗疾病方面的应用.这些研究对于进一步深入理解主客体相互作用的识别机理以及推动超分子化学的发展都具有重要的作用.     

胆酸盐参与的自组装及微纳米材料制备

胆酸盐类物质可看作是一类阴离子型甾族生物表面活性剂,鉴于其特殊的两亲性骨架结构、独特的物理化学性质及其良好的生物相容性和环境友好性,其在溶液中能够参与超分子自组装形成有序聚集结构,且可以作为模板在微纳材料制备领域有着重要应用。本文结合我们课题组的研究工作,综述了近期国内外相关研究,详细介绍了生物小分子氨基酸对胆酸盐聚集行为的影响、胆酸盐参与形成的超分子凝胶及胆酸盐参与构筑的微纳米材料制备等方面的研究进展,以期对胆酸盐参与的自组装及微纳米材料制备领域的研究有更全面更深入的了解,为后续的应用研究提供坚实的基础。     

双组分有机低分子凝胶的研究进展

双组分有机低分子凝胶的研究已成为纳米化学新兴研究领域的热点之一, 形成双组分有机低分子凝胶的有机分子具有多种结构, 例如: 巴比妥酸衍生物、氨基酸衍生物、糖类衍生物、金属有机化合物、胆固醇类衍生物和树枝状分子等. 较系统地综述了目前已知的双组分凝胶及其所涉及的有机低分子凝胶因子的主要结构类型, 并展望了双组分有机低分子凝胶的应用前景.     

凝胶体系中生物分子-金属离子沉淀的LIESEGANG现象研究:胆酸与金属离子形成的周期性沉淀及其影响因素

讨论了凝胶介质、胆酸浓度、金属离子种类及其浓度等因素对胆酸与金属廓了常常的影响规律,实验结果表明：沉淀的ＬＩＥＳＥＧＡＮＧ现象与胆酸分子和金属离子之间的作用有密切的关系。三价稀土离子倾向于和胆酸分子形成周期性环状结构篱子与胆酸分子形成的沉淀形成外貌则比较复杂。有的形成了规则的周期性沉淀环;有的则由较大球形颗粒形成。排列也不规则;还有的在形成环结构时,形成了分形图案。多离子体系中离子之间存在强烈的相     

超分子凝胶:结构多样性与超分子手性

超分子凝胶作为一种重要的软物质材料,在构建多重刺激响应性、光电功能,以及生物相容材料等功能软物质方面表现出了独特的优越性。超分子凝胶在形成过程中往往得到比较均一的纳米结构,且具有结构多样性;而另一方面,超分子凝胶的构筑单元大部分是手性分子,超分子凝胶也是实现手性在超分子层次/纳米层次表达的重要途径,尤其是手性传递、手性放大、不对称催化方面,同时超分子凝胶也是构筑手性纳米结构的重要手段。本文主要对超分子凝胶形成中的纳米结构以及形貌的多样性和超分子手性进行介绍,并展望该领域未来的发展方向。     

超分子凝胶的手性功能应用:手性分子识别与不对称催化

超分子凝胶通过形成三维空间网络结构将溶剂液体相固定化,是一类重要的软物质材料。由于超分子凝胶能快速形成,自组装形成的纳米结构均一、可调,且可大规模制备,因此成为超分子化学、纳米技术以及材料科学研究的重要研究方向之一,并在诸多领域得到广泛的功能研究和应用拓展,如在材料模板、光电开关、药物释放、分子识别和超分子催化等方面已有大量研究报道。由于超分子凝胶具有固-液相可逆转变、可控组装等特性,成为了超分子手性和分子手性研究的重要载体。近年来超分子凝胶在超分子手性催化、手性分子识别等方面取得了一系列重要突破,为超分子凝胶功能应用开辟了新的空间,为手性科学研究提供了新的手段和方法。     

胆酸衍生物的合成及其应用

综述了胆酸衍生物,包括应用于高分子材料、分子识别及医药领域的胆酸衍生物的合成.     

环糊精超分子组装体的研究进展

环糊精是由若干个D-吡喃葡萄糖单元通过α-1,4-糖苷键连接而成的环状低聚糖,具有一个亲水性的外表面和一个疏水性的空腔。利用主客体相互作用,环糊精及其衍生物能够选择性地与大小匹配的疏水性客体分子形成各种超分子包合物。本文概述了环糊精的结构与性质,并介绍了近年来国内外以环糊精为基础的纳米粒子、水凝胶等超分子组装体的设计原理、作用机制、刺激响应及应用特点,并对环糊精超分子组装体的前景进行了展望。     

基于葫芦[10]脲的超分子水凝胶的制备及其在H2O2检测中的应用研究

以丙烯酰胺(AM)与客体单元二茂铁衍生物(G)在引发剂作用下共聚形成P(AM-G)聚合物.基于客体分子与主体分子葫芦[10]脲之间的动态主-客体相互作用为交联点制备了超分子水凝胶.采用核磁、扫描电镜及流变等测试方法对水凝胶的结构、形貌以及自修复性能等进行研究.结果表明超分子水凝胶为3D多孔结构的弹性体,CB[10]的引入有利于在聚合物网络中提供交联点,并且本研究中的超分子水凝胶可在没有任何外部刺激的情况下进行自修复.在水凝胶制备后,二茂铁的固有催化活性仍然得以保留,其良好的催化活性可应用于H_2O_2的检测,检测限为2.5×10~(-4) mol/L.本研究为超分子水凝胶功能化提供了一种新的方法,在生物技术和环境化学等领域具有潜在应用.     

间苯二酚杯芳烃——化学家的建筑积木

间苯二酚杯芳烃是超分子化学的第3代主体分子。介绍了间苯二酚杯芳烃的结构、衍生化途径及其衍生物的用途。     

Progress in the studies of low-molecular mass gelators with unusual properties

This article is intended to provide an overview of recent progress in the studies of cholesterol-based low-molecular mass gelators (LMMGs) with unusual properties,in particular,gelation and selective gelation at room temperature,gel emulsions and gel film formation,etc.Potential applications of the LMMGs in spilled oil collection and water purification are briefly presented.     

具有选择性胶凝能力的小分子胶凝剂研究进展

不相溶混合溶剂的选择性胶凝对于溶剂纯化和分离,特别是溢油处理和水体净化具有十分重要的意义。 具有选择性胶凝能力的胶凝剂可以是高分子、微纳米颗粒和小分子胶凝剂。 然而,相对于高分子和微纳米颗粒材料,以小分子化合物为胶凝剂的凝胶往往具有凝胶 溶胶相变可逆性,这种可逆性无疑会对凝胶体系的实际应用带来额外的好处。 基于这些考虑,本文按照胶凝剂分子的结构,分类介绍此类小分子胶凝剂研究进展,并展望了相关研究的前景和可能应用。     

Highly temperature responsive core-shell magnetic particles: synthesis, characterization and colloidal properties

Three new dimeric cholesterol-based compounds of A(LS)(2) type, where A stands for aromatic component, S steroid moiety, and L a linker connecting the two units, have been designed and prepared. Gelation test in 30 solvents demonstrated that the compounds can gel some of the solvents and form 37 gels, of which 16 form spontaneously at room temperature (~25 °C). These gels possess smart thixotropic properties as revealed by rheological studies. FTIR and (1)H NMR measurements revealed that hydrogen bonding is an important driving force for the formation of the gel networks. XRD analysis demonstrated that unlike commonly found layered structures adopted by dimeric cholesterol-based low-molecular mass gelators (LMMGs), one of the gelators created in this study adopts a hexagonal packing structure in its benzene gel.     

Preparation and gelling properties of sugar-contained low-molecular-mass gelators: Combination of cholesterol and linear glucose

Four novel amphiphilic cholesterol-based and sugar-contained low-molecular-mass gelators (LMMGs) were designed and prepared. According to the structures of the linkers, which are ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, and 1,6-hexane- diamine, these compounds are denoted as 1, 2, 3 and 4, respectively. Gelation tests revealed that 2, 3 and 4 start to gel xylene at concentrations of 0.090%, 0.022%, and 0.016% (w/v), respectively, which are typical ‘super-gelators’. Moreover, these xylene gel systems also possess film formation property. Scanning electron microscopy (SEM) measurements demonstrated that the aggregation behaviors of the compounds are greatly affected by the structures of the linkers. ¹H NMR spectroscopy studies revealed that intermolecular hydrogen bonding formation plays an important role for the formation of the gels. X-ray diffraction (XRD) studies showed that 1 possesses a layered structure in its 1-pentanol gel, a similar structure to that of it in solid state. Gelator 3 also possesses a similar structure in its THF gel, but different from that of it in solid state. Transmission electron microscopy (TEM) observation revealed the helical nature of the nanobelt assemblies of 1 in its 1-pentanol gel.     

含顺反异构双胆固醇型小分子胶凝剂的合成与胶凝行为

以甘氨酸为连接臂,以顺反丁烯二酸为功能基团设计合成了两种具有不同立体异构连接臂的A(LS)2型双胆固醇类小分子胶凝剂MA-C和FA-C. 考察了MA-C和FA-C对30种常见有机溶剂中的胶凝能力. 结果表明：MA-C和FA-C的胶凝能力及其所形成凝胶的性质依赖于胶凝剂分子的立体异构. 值得一提的是,MA-C能使CCl4室温胶凝,而且所形成凝胶具有良好的热稳定性和显著的剪切触变性. 更为有趣的是,此胶凝剂还能在水/CCl4混合体系中选择胶凝有机相. 显微分析表明,凝胶中胶凝剂的聚集体形貌不仅依赖于胶凝剂分子的立体异构,胶凝剂的浓度,而且也和胶凝剂分子与溶剂分子间的相互作用有关. 变温、变浓度1H NMR研究表明胶凝剂分子间的π-π堆积和氢键作用是凝胶形成的重要驱动力. 此外,根据XRD和其它实验结果提出了MA-C在CCl4中的可能堆积模型.     

Stigmasterol-based novel low molecular weight/mass organic gelators

Conjugates consisting of stigmasterol and L-phenylalanine, interconnected through short-chained dicarboxylic acyls by ester and amide bonds, respectively, were synthesized as potential low molecular weight/mass organic gelators (LMWGs/LMMGs). Their physico-chemical properties were subjected to investigation, especially their ability to form gels reversibly based on changes of the environmental conditions. Other self-assembly properties detectable by UV-VIS traces were measured in systems consisting of two miscible solvents (water/acetonitrile) with varying solvent ratios and using constant concentrations of the studied compounds. Partition and diffusion coefficients and solubility in water were calculated for the target conjugates. The conjugate 3a was the only compound from this series capable of forming a gel in 1-octanol. All three conjugates 3a-3c displayed supramolecular characteristics in the UV-VIS spectra.     

Synthesis and post-synthetic derivatization of a cyanine-based amino acid. Application to the preparation of a novel water-soluble NIR dye

An efficient synthesis of a new fluorescent amino acid derived from a pentamethylene cyanine dye is described. Selective derivatization of its amino group with an original trisulfonated linker has led to a novel water-soluble NIR dye suitable for covalent labeling of biomolecules     

Photocatalytic Modification of Amino Acids,Peptides, and Proteins

In the last decade, visible-light photoredox catalysis has emerged as a powerful strategy to enable novel transformations in organic synthesis. Owing to mild reaction conditions (i.e., room temperature, use of visible light) and high functional-group tolerance, photoredox catalysis could represent an ideal strategy for chemoselective biomolecule modification. Indeed, a recent trend in photoredox catalysis is its application to the development of novel methodologies for amino acid modification. Herein, an up-to-date overview of photocatalytic methodologies for the modification of single amino acids, peptides, and proteins is provided. The advantages offered by photoredox catalysis and its suitability in the development of novel biocompatible methodologies are described. In addition, a brief consideration of the current limitations of photocatalytic approaches, as well as future challenges to be addressed, are discussed.     

Metal Triflimidates: Better than Metal Triflates as Catalysts in Organic Synthesis—The Effect of a Highly Delocalized Counteranion

The continuously increasing need for novel and selective methods in organic synthesis to aid drug discovery and to address environmental concerns is a constant source of stimulation to develop novel and more efficient reaction systems. This has often resulted in a focus on transition metals, ligands, and additives, with much less attention paid to the counterion(s) of the metal cation. Recently, metal salts with one or more triflimidate counterion(s) have appeared as a unique class of catalysts that display outstanding σ‐ and π‐Lewis acid character. The highly delocalized nature of the triflimidate counterion, combined with its high steric hindrance results in virtually no nucleophilic behavior and an extremely high positive charge density on the metal cation, thus enhancing its Lewis acid character. Consequently, these metal triflimidates often outperform their metal halide or triflate analogues. This Review describes general methods for the preparation of metal triflimidate salts and their use as catalysts.     

Functionalized 4-hydroxy coumarins: novel synthesis, crystal structure and DFT calculations

A novel short-step methodology for the synthesis in good yields of functionalized coumarins has been developed starting from an activated precursor, the N-hydroxysuccinimide ester of O-acetylsalicylic acid. The procedure is based on a tandem C-acylation-cyclization process under mild reaction conditions. The structure of 3-methoxycarbonyl-4-hydroxy coumarin has been established by X-ray diffraction analysis and its geometry was compared with optimized parameters by means of DFT calculations.