Introducing Chirality into Nonionic Dendritic Amphiphiles and Studying Their Supramolecular Assembly

Chiral head groups have been introduced into water‐soluble hydroxyl‐terminated nonionic amphiphiles and the impact of the head group stereochemistry on the supramolecular ultrastructures has been studied. Enantiomeric isomers were compared with the achiral meso form and the racemic mixture by means of cryogenic transmission electron microscopy and circular dichroism spectroscopy. Structurally, all amphiphiles are composed of the first‐generation hydrophilic polyglycerol head group coupled to a single hydrophobic hexadecyl chain through an amide linkage and diaromatic spacer. The enantiomers aggregate to form twisted ribbons with uniform handedness, whereas the meso stereoisomer and racemic mixture produce elongated assemblies, namely, tubules and platelets, but without a chiral ultrastructure. Simulations on the molecular packing geometries of the stereoisomers indicate different preferential assembly routes that explain the individual supramolecular aggregation behavior.     

Histidinium-Driven Chirality Control of Self-Assembled Hybrid Molybdenum Oxyfluorides

Exploring macroscopic chiral materials with extended structures has become an important and fundamental topic in chemistry. To systematically control the chirality of novel organic–inorganic frameworks, histidinium-based cationic structure-directing agents containing specific chiral information are introduced. In this way, two chiral compounds, [(l -hisH₂)MoO₂F₄]₃ ⋅ H₂O ( L ) and [(d -hisH₂)MoO₂F₄]₃ ⋅ H₂O ( D ), and an achiral oxyfluoride, (l /d -hisH₂)MoO₂F₄ ( LD ) (his=histidine, C₆H₉N₃O₂) have been successfully self-assembled by a slow evaporation method. The structures of these compounds are composed of histidinium cations and distorted [MoO₂F₄]²⁻ octahedra. Surprisingly, the histidinium cations not only control macroscopic chirality, but also induce O/F ordering in MoO₂F₄ octahedra through hydrogen-bonding interactions. Compounds L and D crystallize in the extremely rare polar space group P1, and exhibit positive second harmonic generation (SHG) signals attributable to a net moment originating from the MoO₂F₄ groups. Solid-state circular dichroism (CD) spectra indicate that the MoO₂F₄ units templated by histidinium cations are chirally aligned through ionic interactions. Crystallization processes influenced by the chirality of the reported materials are also discussed herein.     

基于超分子环糊精两亲分子的敏感型囊泡体系

敏感型囊泡可初步概括为由两亲分子通过非共价键构筑的、对外界的刺激具有特色响应性的一类新型囊泡体系。由"超分子环糊精两亲分子"自组装形成的囊泡体系是该类体系中重要的一类。本文重点介绍了环糊精参与的"超分子环糊精两亲分子"囊泡体系的研究进展。以与环糊精复合的化合物结构类型不同进行分类,介绍了该类囊泡体系的制备以及该体系在医药工程、新型"智能"材料以及生物模拟等方面的潜在应用;结合现阶段的研究状况,对该类囊泡体系的发展前景进行了展望。     

Nanostructured Micelle Nanotubes Self-Assembled from Dinucleobase Monomers in Water

Despite the central importance of aqueous amphiphile assemblies in science and industry, the size and shape of these nano-objects is often difficult to control with accuracy owing to the non-directional nature of the hydrophobic interactions that sustain them. Here, using a bioinspired strategy that consists of programming an amphiphile with shielded directional Watson–Crick hydrogen-bonding functions, its self-assembly in water was guided toward a novel family of chiral micelle nanotubes with partially filled lipophilic pores of about 2 nm in diameter. Moreover, these tailored nanotubes are successfully demonstrated to extract and host molecules that are complementary in size and chemical affinity.     

二(o-溴苄基)锡双(二乙基二硫代氨基甲酸)酯和二(o-氯苄基)锡双(吡咯啶二硫代氨基甲酸)酯的合成、结构及体外抗癌活性研究

二(o-溴苄基)二溴化锡和二(o-氯苄基)二氯化锡分别与N,N-二乙基二硫代氨基甲酸钠和吡咯啶二硫代氨基甲酸钠反应,合成了二(o-溴苄基)锡双(二乙基二硫代氨基甲酸)酯(1)和二(o-氯苄基)锡双(吡咯啶二硫代氨基甲酸)酯(2)。用X-射线单晶衍射测定了两个化合物的晶体结构,测试结果表明:化合物1的晶体为单斜晶系,空间群P21/c,晶体学参数a=1.827 36(4)nm,b=0.900 60(2)nm,c=1.988 41(5)nm,β=114.878 0(10)°,V=2.968 71(12)nm3,Z=4,Dc=1.690 g·cm-3,μ(Mo Kα)=38.50 cm-1,F(000)=1 496,R1=0.051 6,wR2=0.154 6。化合物2的晶体为单斜晶系,空间群C2/c,晶体学参数a=2.241 28(4)nm,b=0.818 78(2)nm,c=1.542 69(3)nm,β=106.787 0(10)°,V=2.710 37(10)nm3,Z=4,Dc=1.623 g·cm-3,μ(Mo Kα)=14.65 cm-1,F(000)=1 336,R1=0.022 9,wR2=0.056 5。晶体中锡原子呈六配位畸变八面体构型。对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及部分前沿分子轨道的组成特征。测定了配合物的热稳定性和体外抗癌活性。     

Synthesis and Thermal Rearrangement of Tetramethyldisilane-bridged Bis(cyclopentadienyl) Diiron Complexes with Bis(phosphine)Substitution

Photolysis of [Me2SiSiMe2)[C5H4Fe(CO2)]2with a series of bis(phosphine)ligands Ph2P(CH2)n PPh2(n=1-4) leads to the formation of the corresponding diiron complexes with intramolecular and intermolecular bis(phosphine) substitution.When these complexes were heated in refluxing xylene.only in the complexes with intermolecular bis(phosphine )substitution the thermal rearrangement reaction occurred.     

Tuning the Supramolecular Chirality of Polyaniline by Methyl Substitution

A game of Twister : The induced helicity of polyaniline and its supramolecular structures could be tuned by the methyl substitution of one of the monomers. By copolymerization of aniline with m‐toluidine, the helicity of copolymer (PMANI) nanofibers was totally inverted compared to that of polyaniline (PANI), while copolymer nanofibers with o‐toluidine (POANI) had the same helicity as that of polyaniline (see picture).

     

C2对称的手性双噁唑啉和双噻唑啉的质谱碎裂机理研究

The electron impact mass spectra of ten new C2-symmetric chiral bis(oxazoline) and bis(thiazoline) have been studied. Bis(thiazoline) and bis(oxazoline) possess the same fragmentation mechanism under EI conditions. An unusual fragmentation pathway has been found in the compounds studied. Due to the presence of phenyl group, compounds 6 and 10 undergo a new fragmentation pathway except for the common way as the other eight compounds.Mass analyzed ion kinetic energy spectra experiments and high resolution accurate mass measurement were conducted to confirm the proposed fragmentation pathways.     

手性双噁唑啉配体的合成进展

总结了近年来用于不对称催化的各种双噁唑啉配体的合成方法,包括丙二酸酯类、酒石酸类、吡啶类、联苯、联萘及二茂铁类等多种双噁唑啉配体的合成.另外,还讨论了苯甲醚类、二联苯噁二唑类、联苯胺类与氮杂类等新型双噁唑啉配体的合成.     

手性双噁唑啉配体在不对称合成中的应用

双噁唑啉手性配体已广泛用于不对称Henry反应、环丙烷化反应、Aldol反应、烷基化反应、环加成反应中,并表现出很高的对映选择性和催化活性,成为最有用的手性配体之一。文章综述了近10年来双噁唑啉手性配体及高分子受载手性双噁唑啉在不对称合成中的研究进展。     

手性二噁唑啉吡啶铁和镍配合物的制备与表征

Tridentate bis(oxazolinylpyridine)(1) reacted with nickel chloride or ferrous chloride in anhydrous ethanol to form bis(oxazolinylpyridine) Nickel(Ⅱ) and Iron(Ⅱ) complexes. The stable solid complexes were characterized with IR， UV， MS， XPS and elemental analysis. No stable complexes were formed with bidentate bis(oxazoline)(2) ins- tead of bis(oxazolinylpyridine).     

偶氮苯修饰DNA的组装行为及主客体作用介导的形貌调控

智能型DNA纳米材料,由于其具有灵敏的外界刺激响应性,是纳米技术和生物医学应用中一类重要的功能纳米材料。本文研究的具有光响应性质的偶氮苯共价修饰DNA的两亲分子在水相中可组装成直径为28.8nm的球形胶束,光刺激或者β-环糊精与偶氮苯的主客体识别的调控均可实现组装解离,进一步通过荧光包裹实验和金纳米颗粒负载实验验证了球形胶束的组装机制,为其在药物负载、靶向识别等生物医学领域提供了潜在应用。     

Bis(dicarbollide) Complexes of Transition Metals as a Platform for Molecular Switches. Study of Complexation of 8,8′-Bis(methylsulfanyl) Derivatives of Cobalt and Iron Bis(dicarbollides)

Complexation of the 8,8′-bis(methylsulfanyl) derivatives of cobalt and iron bis(dicarbollides) [8,8′-(MeS)₂-3,3′-M(1,2-C₂B₉H₁₀)₂]⁻ (M = Co, Fe) with copper, silver, palladium and rhodium leads to the formation of the corresponding chelate complexes, which is accompanied by a transition from the transoid to the cisoid conformation of the bis(dicarbollide) complex. This transition is reversible and can be used in design of coordination-driven molecular switches based on transition metal bis(dicarbollide) complexes. The solid-state structures of {(Ph₃P)ClPd[8,8′- (MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂-κ²-S,S′]} and {(COD)Rh[8,8′-(MeS)₂-3,3′-Co(1,2-C₂B₉H₁₀)₂-κ²-S,S′]} were determined by single crystal X-ray diffraction.     

双马来腈二亚胺合铂与DNA的作用

本文以紫外-可见光谱、荧光光谱及黏度法研究了双马来腈二亚胺合铂与DNA的作用。紫外-可见光谱的研究表明,与DNA作用后,双马来腈二亚胺合铂在可见区的吸收显示出了减色效应,并伴随着吸收峰的蓝移。Scatchard图的分析结果表明,双马来腈二亚胺合铂与DNA的作用位点与溴化乙锭不同。黏度法实验表明,双马来腈二亚胺合铂与DNA作用后降低了DNA的相对黏度。这些研究结果表明,双马来腈二亚胺合铂以静电作用方式与DNA结合。本研究有助于深入理解双马来腈二亚胺合铂的作用机理并开发这种潜在的新型光动力治疗剂。     

A Chiral Recognition System Orchestrated by Self‐Assembly: Molecular Chirality,Self‐Assembly Morphology,and Fluorescence Response

The newly developed oligophenylenevinylene (OPV)‐based fluorescent (FL) chiral chemosensor (OPV‐Me) for the representative enantiomeric guest, 1,2‐cyclohexanedicarboxylic acid (1,2‐CHDA: RR ‐ and SS ‐form) showed the high chiral discrimination ability, resulting in the different aggregation modes of OPV‐Me self‐assembly: RR ‐CHDA directed the fibrous supramolecular aggregate, whereas SS ‐CHDA directed the finite aggregate. The consequent FL intensity toward RR ‐CHDA was up to 30 times larger than that toward SS ‐CHDA. Accordingly, highly enantioselective recognition was achieved. Application to the chirality sensing was also possible: OPV‐Me exhibited a linear relationship between the FL intensity and the enantiomeric excess through the morphological development of stereocomplex aggregates. These results clearly show that the chiral recognition ability is manifested by the amplification cascade of the chirality difference through self‐assembly.     

Chirality Enhancement of Porphyrin Supramolecular Assembly Driven by a Template Preorganization Effect

Cationic polylysine promotes, under neutral conditions, the spontaneous aggregation of opposite charged ZnTPPS in water. Spectroscopic investigations evidence a different preorganization of ZnTPPS onto the polypeptide matrix depending on the chain length. Spinodal decomposition theory in confined geometry is used to model this mechanism by considering the time evolution of a homogeneous distribution of randomly adsorbed particles (porphyrins) onto a rodlike polyelectrolyte (polymer) of variable length L.     

Breaking the Odd–Even Effect in the Self‐Assembly of Linear Bis(benzamides)

The twisting of supramolecular aggregates formed from simple linear bis(benzamides) has been investigated. The antiparallel arrangement of the amide functional groups controls the generation of twisted supramolecular structures. The results presented herein could contribute to elaborate predictive tools applicable in the generation of chiral supramolecular structures.     

Synthese von Mono- und Bis(silyl)hydroxylaminen

Synthesis of Mono- and Bis(silyl)hydroxylamines Silylamines reacts with hydroxylaminehydrochlorid to give the monosilylhydroxylamines: R₂FSiONH₂ (R = CMe₃ 1 ), R₂R′SiONH₂ (R = CMe₃, R′ = Me 2 ), R₂(NH₂)SiONH₂ (R = CMe₃ 3 ). The reaction of 1 in the present of HCl-acceptors or the reaction of lithiated 1 with Me₃SiCl or F₂Si(CMe₃)₂ leads to the formation of bis(silyl)hydroxylamines, (Me₃C)₂FSiONHSiMe₃ 4 , and (Me₃C)₂FSiONHSiF(CMe₃)₂ 5 . The lithium derivatives of Me₃SiONH₂ and 2 react with fluorosilanes to the bis(silyl)hydroxylamines: Me₃SiONHSiFRR′ (R = R′ = CMe₃, 6 , R = CMe₃, R′ = F 7 , R = R′ = NMeSiMe₃ 8 ), (Me₃C)₂MeSiNHOSiFRR′ (R = CMe₃, R′ = F 9 , R = (Me₃C)₃C₆H₂, R′ = F 10 , R = R′ = CMe₃ 11 , R = R′ = CHMe₂ 12 ). The bis(silyl)hydroxylamines 4 and 6 are structure isomers.