基于手性冠醚的对映选择性识别研究进展

介绍了冠醚类化合物的结构特点及络合性能、冠醚的络合作用和识别分子的新进展.冠醚类化合物因其稳定的构象和易于修饰的特点,成为研究最为广泛的主体分子之一,其中大量的文献报道了能够用于对映选择性识别和检测的手性冠醚.在分子识别的研究中,核磁、荧光、紫外和质谱是四种最常见的研究方法,总结了近年来手性冠醚运用这四种方法在对映选择性识别领域的最新研究进展并对手性冠醚的发展前景作了展望.     

介孔二氧化硅对映选择性吸附的手性印迹调控

使用手性阴离子表面活性剂作为超分子模板, 采用共结构导向法制备手性介孔二氧化硅(CMS), 并运用圆二色谱(CD)对CMS对映选择性吸附结果进行检测, 比较了有无共结构导向剂(CSDA)在介孔表面的排列对吸附选择性的影响. 结果表明, 当使用构型相反的手性超分子模板剂对原合成CMS材料的介孔内表面进行修饰时, 可诱导结构共导向剂N?三甲氧基硅基丙基?N, N, N?三甲基氯化铵(TMAPS)发生手性相反的排列进而导致完全相反的对映选择性吸附. 实验证明此方法合成的CMS的对映选择性吸附及分离能力主要是由修饰在介孔表面的TMAPS螺旋排列形成的手性印迹所导致. 此手性超分子模板诱导TMAPS手性印迹的策略具有一定的普适性, 可对原合成介孔材料对映选择性吸附进行原位调控, 对于拓展其在立体选择性识别、 不对称催化及药物输送等方面的应用具有一定的指导意义.     

手性药物的对映体选择性释放

手性和手性物质的重要性已不言而喻,手性药物的开发也已成为主要发展趋势,但目前仍有部分手性药物以消旋体的形式出售和使用。如何合理、有效地使用这些消旋体药物,一直是值得深入研究的课题。对映体选择性释放将手性拆分和控释两个概念结合于一体,有望为消旋体药物的使用提供新的途径。基于本课题组的研究,本文综述了近年来对映体选择性释放研究领域所取得的主要进展。为便于讨论,本文根据构成药物控释载体的手性分子或结构(手性因素),将手性药物释放体系分为有机材料(水凝胶和粒子等)、无机材料和分子印迹材料等控释体系。关于对映体选择性释放以及释放过程中的对映选择性作用的研究,可进一步提升我们对于手性、手性物质和手性作用的认识。     

手性超分子组装研究进展

介绍了超分子手性的基本构筑方式及其特点,分别从手性分子组装、手性分子诱导非手性分子及非手性分子组装等3个方面对最近几年来在手性超分子组装领域内的重要成果及最新进展进行了综述,并对这一领域的发展前景作了展望。     

手性杯芳烃及其超分子手性

杯芳烃是由苯酚单元通过亚甲基连接而成的空腔型分子,具有衍生位点多,构象丰富等特点,被称为第三代主体分子。在分子层次,依手性因素的结构特点不同,可将手性杯芳烃分为具有手性亚单元的杯芳烃、固有手性杯芳烃和桥手性杯芳烃。在超分子层次,杯芳烃自身或杯芳烃与其他分子或离子在溶液中、晶态中或二维表面可通过非共价键力形成多种拓扑结构的纳米手性聚集体。研究手性杯芳烃和基于杯芳烃的超分子手性组装体的合成、结构和性能,不仅在理解手性起源、手性结构等方面具有理论意义,而且有望获得以分子识别为基础的手性传感器、手性催化剂、手性分离材料、手性载体和手性纳米材料。本文综述近十年来有代表性的分子手性杯芳烃和以杯芳烃为组分的超分子手性聚集体的设计、合成、结构和功能。着重展示杯芳烃骨架在形成新颖分子手性和超分子手性上的优势,以及杯芳烃单元在实现特定功能如手性识别时发挥的作用。相信随着杯芳烃合成技术和杯芳烃超分子设计的发展,必将进一步发挥杯芳烃的结构优势,涌现出更多性能优异的手性杯芳烃功能分子和超分子手性杯芳烃功能材料。     

金纳米簇-多金属氧酸盐复合物的制备及催化选择性氧化环已烯性能研究

通过4-N,N二甲基胺基吡啶和多金属氧酸负离子形成的复合载体稳定金纳米颗粒,制得金纳米簇-多金属氧酸盐的复合物.复合物的组成以及金纳米颗粒的分布状态由XPS和TEM表征.利用多金属氧酸和金纳米颗粒的相互协助作用,使得这类复合物是一种优异的低温选择性氧化催化剂.     

原位氧化复合法制备聚苯胺/金纳米纤维及过氧化氢生物传感器的构建

采用原位氧化复合法制备了聚苯胺/金纳米纤维,并将其固载在玻碳电极上构建了一种新型的过氧化氢生物传感器。该传感器对过氧化氢的还原具有良好的催化活性,在优化的实验条件下,该传感器对过氧化氢测定的线性范围为1.010-6～1.0510-4mol/L,检出限为5.7510-7mol/L(S/N=3)。     

亚胺的对映选择性催化还原研究进展

亚胺的对映选择性催化氢化是近年来不对称催化反应中的一个新热点, 本文综述了自1973 年Kagan 等人首次报道亚胺对映选择性催化还原以来本领域的研究进展。     

手性离子液体修饰纳米金粒子用于酪氨酸对映体的手性识别

本文以手性离子液体1-乙基-3-甲基咪唑L-酒石酸盐(EMIML-Tar)为修饰剂合成了EMIML-Tar修饰的金纳米粒子(EMIML-Tar-AuNPs)。采用透射电镜、紫外-可见分光光度计对EMIML-Tar-AuNPs进行了表征。合成的EMIML-Tar-AuNPs平均粒径约为6.5nm,其紫外-可见吸收光谱的最大吸收波长为520nm。进一步将EMIML-Tar-AuNPs用于酪氨酸(Tyr)对映体的手性识别,观察添加不同浓度D-Tyr和L-Tyr的EMIML-Tar-AuNPs的颜色变化及其紫外-可见吸收光谱。结果表明,经过D-Tyr和L-Tyr处理的EMIML-Tar-AuNPs胶体的颜色不同,而且紫外-可见光谱图也存在明显差异。对各浓度光谱图在650nm和520nm处的吸光度比值进行比较,结果发现各浓度D-Tyr的吸光度比值均较低且差别不大,而L-Tyr的吸光度比值均较高,且随着浓度的增大会出现大幅度增加。     

超分子手性组装体的构建与应用

超分子手性组装体通常由多种非共价相互作用协同驱动形成,是一类具有独特手性限域微环境的软物质,对材料工程、生命科学、光学器件、催化合成等领域的发展具有重要作用.其主要构建方法分为三种;手性基元组装、手性因素诱导非手性基元组装、非手性基元对称性破缺组装.通过分析近年来的研究成果,归纳了利用这三种方法构建超分子手性组装体的一...     

Helical Chiral N-Heterocyclic Carbene Ligands in Enantioselective Gold Catalysis

The first chiral helicene-NHC gold(I) complexes efficient in enantioselective catalysis were prepared. The L-shaped chiral ligand is composed of an imidazo[1,5-a]pyridin-3-ylidene (IPy) scaffold laterally substituted by a configurationally stable [5]-helicenoid unit. The chiral information was introduced in a key post-functionalization step of a NHC-gold(I) complex bearing a symmetrical anionic fluoreno[5]helicene substituent, leading to a racemic mixture of complexes featuring three correlated elements of chirality, namely central, axial and helical chirality. After HPLC enantiomeric resolution, X-ray crystallography and theoretical calculations enabled structural and stereochemical characterization of these configurationally stable NHC-gold(I) complexes. The high potential in asymmetric catalysis is demonstrated in the benchmark cycloisomerization of N-tethered 1,6-enynes with up to 95 : 5 er.     

Asymmetric Catalysis. Part 149 [1]. Synthesis of New Chiral Tridentate Ligands for Enantioselective Catalysis

Summary. The synthesis of new chiral tridentate ligands is reported which coordinate transition metals in a meridional way. The ligands contain a pyridine ring, an oxazoline ring, and a strongly coordinating diphenylphosphanyl group. The methionine-derived ligand forms a copper complex, which has been studied by X-ray crystallography. The new ligands were tested in models of enantioselective catalyses, such as hydrogenation of ketopantolactone, hydrosilylation of acetophenone, and transfer hydrogenation of acetophenone.X-ray structure analysesReceived March 4, 2003; accepted March 4, 2003 Published online August 18, 2003     

Exploitation of Catalytic Dyads by Short Peptide-Based Nanotubes for Enantioselective Covalent Catalysis

Extant enzymes with precisely arranged multiple residues in their three-dimensional binding pockets are capable of exhibiting remarkable stereoselectivity towards a racemic mixture of substrates. However, how early protein folds that possibly featured short peptide fragments facilitated enantioselective catalytic transformations important for the emergence of homochirality still remains an intriguing open question. Herein, enantioselective hydrolysis was shown by short peptide-based nanotubes that could exploit multiple solvent-exposed residues to create chiral binding grooves to covalently interact and subsequently hydrolyse one enantiomer preferentially from a racemic pool. Single or double-site chiral mutations led to opposite but diminished and even complete loss of enantioselectivities, suggesting the critical roles of the binding enthalpies from the precise localization of the active site residues, despite the short sequence lengths. This work underpins the enantioselective catalytic prowess of short peptide-based folds and argues their possible role in the emergence of homochiral chemical inventory.     

Supramolecular Coordination Cages for Asymmetric Catalysis

Inspired by the high efficiency and specificity of enzymes in living systems, the development of artificial catalysts intrinsic to the key features of enzyme has emerged as an active field. Recent advances in supramolecular chemistry have shown that supramolecular coordination cages, built from non-covalent coordination bonds, offer a diverse platform for enzyme mimics. Their inherent confined cavity, analogous to the binding pocket of an enzyme, and the facile tunability of building blocks are essential for substrate recognition, transition-state stabilization, and product release. In particular, the combination of chirality with supramolecular coordination cages will undoubtedly create an asymmetric microenvironment for promoting enantioselective transformation, thus providing not only a way to make synthetically useful asymmetric catalysts, but also a model to gain a better understanding for the fundamental principles of enzymatic catalysis in a chiral environment. The focus here is on recent progress of supramolecular coordination cages for asymmetric catalysis, and based on how supramolecular coordination cages function as reaction vessels, three approaches have been demonstrated. The aim of this review is to offer researchers general guidance and insight into the rational design of sophisticated cage containers for asymmetric catalysis.     

无机手性纳米结构的可控构筑及其催化研究进展

具有强烈光学活性的无机手性结构因其具有独特的物理化学性质, 可将手性信号扩展至可见和近红外区域, 对于手性的检测与分析、手性合成、手性传感及相关光电领域的研究具有重要意义. 在过去的二十年里, 人们对无机手性结构进行了大量的研究, 从合成方法、手性起源理论到实际应用都取得了长足的进展. 重点聚焦具有手性催化应用潜力的无机手性纳米材料, 首先介绍了单个无机手性纳米粒子独特的手性效应、常用的构筑方法和手性起源机理, 并简要概述了无机纳米粒子作为构筑单元形成手性多级纳米结构的组装方法. 重点关注了无机手性纳米材料在手性催化领域的应用, 讨论了手性金属纳米结构、手性半导体纳米结构、手性陶瓷纳米结构及手性磁性纳米粒子用于手性催化的相关机理, 并对有代表性的最新进展进行了分析. 最后, 梳理了目前无机手性结构及其催化性能存在的不足和面临的挑战, 并对未来的研究方向进行了展望.     

手性药物与生物大分子相互作用中对映选择性的表征方法研究进展

手性药物在临床上有着重要的影响,已成为人们关注的一个重点问题。本文对手性药物小分子与生物大分子间相互作用中对映选择性分析方法的研究进展作了概述,重点介绍了分子光谱分析法、等温滴定量热法、手性传感器、原子力显微镜、分子对接模拟等方法在手性药物小分子与生物大分子间对映选择性相互作用表征方法中的应用与进展。     

Synthesis of Chiral Pyridylphenols for the Enantioselective Addition of Diethylzinc to Aldehydes

Chiral 8‐substituted 2‐(8,10,10‐trimethyl‐6‐aza‐tricyclo[7.1.1.0^2,7]undeca‐2(7),3,5‐trien‐5‐yl)‐phenols were prepared from a high enantiopurity (>97% ee) of (1R)‐(+)‐α‐pinene, and assessed in the enantioselective addition of diethylzinc to substituted benzaldehydes, giving the (S)‐alcohols with enantiomeric excess ranging from 33% to 89%. Interestingly, in all cases, except for those of ortho‐chlorobenzaldehyde, ortho‐ and para‐methoxybenzaldehydes, the ee was >71%. The plot of the Hammett substitution constants vs. enantiomeric excess of the diethylzinc addition to either the ortho‐ or para‐substituted benzaldehydes shows a linear correlation.     

A new pyrrolidine-derived atropisomeric amino alcohol as a highly efficient chiral ligand for the asymmetric addition of diethylzinc to aldehydes

A highly efficient pyrrolidine-derived atropisomeric amino alcohol, (S_a)-1-[2-diphenylhydroxymethyl-6-(trifluoromethyl)phenyl]-2-(1-pyrrolido)methyl-1H-pyrrole, has been synthesized as a chiral ligand for the enantioselective addition of diethylzinc to some prochiral aldehydes to afford (S)-alcohols. The conversion rates were close to quantitative with good to excellent enantiomeric excesses (up to 95% ee).