含有α-CD的新型[2]轮烷的合成

通过醋酸钯催化的Suzuki偶联反应,在室温下于水溶液中通过超分子自组装制备了以α-CD(α-环糊精)为大环,异酞酸为端塞,二苯乙烯衍生物为链的新型超分子轮烷。通过加入浓HCl调节反应溶液的pH值<1,用正丁醇萃取,将含有α-CD大环的轮烷分子与水溶液中多余的α-CD分离,再用硅胶柱层析分离得到纯的只含有1个α-CD大环的轮烷分子,从而简化了分离难度。采用1HNMR和质谱分析结果表明,所制得的轮烷为α-CD(主体)与哑铃状分子(客体)的摩尔比为1:1的[2]轮烷。     

轮烷研究－从超分子组装到分子器件

轮烷是一类由两端带有大的基团的线性分子和有机环化合物组成的互相锁连的分子化合物。主要综述了近年来这类超分子化合物的合成方法进展、在合成中的应用及其作为分子器件方面的研究进展。     

准聚轮烷的研究进展

准聚轮烷由于在刺激响应性材料、自修复材料、分子机器及荧光传感器等领域有着潜在的应用价值,近年来引起了研究人员极大的兴趣。根据准轮烷基团所处位置的不同,可将准聚轮烷分为三种类型：主链型、侧链型和其他类型 （如支化和网状准聚轮烷等）。本综述主要根据上述三种类型,基于冠醚、环糊精、杯芳烃、葫芦脲和柱芳烃这五种超分子主体分子所构筑的准聚轮烷的最新研究进展进行简要的综述,并对其未来的发展作了进一步的展望。     

含两个识别点的侧链准聚轮烷的制备

合成了侧链含烷基链(C₇)及偶氮基团(Azo)两个疏水基团修饰的聚合物4,并基于环糊精与两个疏水基团C₇、Azo的不同结合能力,制备了含两个识别点的侧链准聚轮烷.首先,在聚合物4的溶液中加入α-环糊精(α-CD),α-CD分别包结在C₇及Azo部分,得到了侧链准聚轮烷;第二步,在365 nm的紫外光光照下,聚合物4侧链端基的trans-Azo异构为cis-Azo,α-CD从Azo部分解离,但α-CD仍包结在C₇部分,得到了侧链聚轮烷;第三步,在侧链聚轮烷溶液中加入β-环糊精(β-CD),β-CD包结在cis-Azo部分,得到了α-CD、β-CD分别包结两个疏水识别点的侧链准聚轮烷.     

化学驱动的[2]轮烷型分子梭

机械互锁的轮烷型分子梭在分子机器化学领域具有重要的位置,可通过"积小为大"的方法在分子水平进行新材料的自组装.在外界的刺激下,大环分子可以在轴分子的不同识别位点间或态间往复穿梭,从而引起体系物理或化学性质的交替变化,这种变化又构成了一类基本的机械开关,可以用来执行特定的功能,在分子开关、信息储存和处理等领域具有潜在的应用前景,是超分子化学领域的研究热点.本文以[2]轮烷型分子梭的驱动力(外部刺激)为主线,分别从酸碱驱动、离子配位作用驱动和溶剂极性改变引起的疏水驱动等角度,综述了近年来化学驱动的[2]轮烷型分子梭在合成和应用方面的最新研究进展,同时介绍了其他力(如热力学参数熵、互锁体系中修饰基团尺寸大小、外加化学氧化剂或还原剂、得失电子引起的电化学氧化还原以及紫外-可见光照射诱发的偶氮苯顺反光异构化等方式)驱动的轮烷型分子梭的进展,最后对化学驱动的[2]轮烷型分子梭的未来发展趋势进行了展望.     

基于柱[n]芳烃(准)轮烷的研究进展

柱芳烃作为一类新型的大环主体分子,自2008年首次报道以来,引起了人们,特别是化学家的广泛关注.目前,它已在分子识别、(准)轮烷、超分子聚合物、分子弹簧、智能跨膜离子通道、囊泡、金属有机骨架结构等众多研究领域作为重要模块得到初步的应用.主要将以柱芳烃作为主体大环分子来构筑(准)轮烷的研究进展进行简要的综述,同时还介绍了基于柱芳烃的(准)聚轮烷的研究概况,并对未来的发展作了进一步展望.     

一锅法合成基于丁二炔-苯环冠醚的[2]轮烷

以丁二炔-苯环冠醚作为大环化合物,以带有4,4'-联吡啶正离子结构的线性分子作为半封端分子,通过简便的一锅法合成一种新的[2]轮烷分子,产率为24%.经高分辨质谱、核磁共振氢谱、核磁共振碳谱等手段确认了丁二炔-苯环冠醚大环与带有两个4,4'-联吡啶二正离子的线性封端分子组装形成[2]轮烷结构,且丁二炔-苯环冠醚在线性分子的两个识别点间作往返运动.     

分子机器的研究进展

结合分子机器的基本概念、合成方法、驱动方式以及研究的意义, 综述了近几年分子机器的研究进展, 探讨了下一步研究的发展方向.     

一种类似准[5]轮烷的β-胡萝卜素-β-环糊精包合物的制备与表征

用饱和溶液法在1∶1的乙醇—水体系中制备了β 胡萝卜素(β C)-β 环糊精(β CD)的准[5]轮烷超分子包合物.紫外可见光度法和元素分析均证明了4轮体的存在.FTIR、X 射线粉末衍射和1HNMR技术为轮烷超分子化合物的形成提供了有力的佐证.     

葫芦脲超分子(准)聚轮烷的研究进展

综述了一类新型超分子葫芦脲(准)聚轮烷的最新研究进展,包括一维、二维、三维金属(准)聚轮烷,主链、侧链有机(准)聚轮烷和树状大分子(准)聚轮烷的最新研究情况,并对超分子(准)聚轮烷的前景进行了展望。     

Rotaxane络合物研究新进展

Rotaxane是在带有长链的分子上套入环状化合物的特铁络合物。本文综述了rotaxane络合物,特别是环状化合物为环糊精( cyclodextrin, CD)的rotaxane-CD络合物的组成、合成,一些性质和应用以及研兄方法,并提出了应予重视的研完方面。     

Rotaxane Type Complexation Behavior of Cyclodextrins with Zinc (II) Tetraphenylporphyrin-Viologen Linked Compounds

The complexation behavior of zinc (II) tetraphenylporphyrin-viologen covalently linkedcompounds by a polymethylene chain (ZnPC_nV²⁺; n = 4–9) withtri-O-methyl--cyclodextrin (TM--CD) was investigated by meansof ¹H NMR and UV/Vis absorption spectrometry in acetonitrile-water (1:1, v/v).The ¹H NMR spectra indicated that ZnPC_nV²⁺ existed as a mixture ofa dimer and a monomer at high concentration (>1 × 10^-3 M). The dimerwas degraded to the monomer upon complexation with TM--CD involving theformation of 1:1 and 1:2 (ZnPC_nV²⁺: TM--CD) complexes, whichwas observed by UV/Vis spectrometry. Furthermore, ¹H NMR spectra exhibitedthat there are at least two types of structures for these complexes, one is a fastexchanging complex, and another is a slow exchanging one. A slow exchanging complexcould be assigned as a rotaxane type structure in which the methylene chain moiety ofZnPC_nV²⁺ penetrated into the cavity of TM--CD. Discrete formationconstants for these complexes were evaluated. The values were little affected by the spacermethylene chain length (n 7).     

Synthesis and Properties of Porphyrin Nanotubes

Discrete π‐conjugated zinc porphyrin nanotubes are investigated as molecular analogues of carbon nanotubes. These porphyrin nanotubes have a diameter of 2.4 nm (Zn–Zn distance) and lengths of up to 3.6 nm, measured to the van der Waals surfaces of the outer β‐pyrrole hydrogen atoms, or 4.5 nm measured to the para hydrogen atoms of the aryl groups. We explore three different strategies for synthesizing these nanotubes. The first two strategies use a template to achieve direct or sequential stave‐joining, respectively, and proceed via linear oligomers that pre‐define the length of the nanotube. These strategies are applied to synthesize porphyrin nanotubes containing 12‐ or 18‐porphyrin subunits, with ethynylene (C₂) or butadiynylene (C₄) links between the 6‐porphyrin nanorings. The third strategy involves the covalent stacking of pre‐formed 6‐porphyrin nanorings to form a 12‐porphyrin nanotube, without using a template to guide this coupling reaction. The nanotubes show strongly red‐shifted absorption spectra and low fluorescence quantum yields, indicating structural rigidity and extensive π‐conjugation.     

Rotaxane Type Complexation Behavior of Cyclodextrins with a Series of Donor–Acceptor Covarently Linked Compounds

The complexation behavior of a series of electron donor–accepter (D–A) covalently linked compounds with cyclodextrins (CyDs) has been reviewed. The structure of these complexes showed rotaxane type conformations, which were investigated by means of ¹ H NMR spectrometry. The complex formations induced a fixation of a conformation of guest D–A molecules, and D–A distances were enlarged. Thus, accurate photo-induced charge transfer behaviors can be discussed.     

Remote Control of the Synthesis of a [2]Rotaxane and its Shuttling via Metal-Ion Translocation

Remote control in an eight-component network commanded both the synthesis and shuttling of a [2]rotaxane via metal-ion translocation, the latter being easily monitored by distinct colorimetric and fluorimetric signals. Addition of zinc(II) ions to the red colored copper-ion relay station rapidly liberated copper(I) ions and afforded the corresponding zinc complex that was visualized by a bright sky blue fluorescence at 460 nm. In a mixture of all eight components of the network, the liberated copper(I) ions were translocated to a macrocycle that catalyzed formation of a rotaxane by a double-click reaction of acetylenic and diazide compounds. The shuttling frequency in the copper-loaded [2]rotaxane was determined to k₂₉₈=30 kHz (ΔH^≠=62.3±0.6 kJ mol⁻¹, ΔS^≠=50.1±5.1 J mol⁻¹ K⁻¹, ΔG^≠₂₉₈=47.4 kJ mol⁻¹). Removal of zinc(II) ions from the mixture reversed the system back generating the metal-free rotaxane. Further alternate addition and removal of Zn²⁺ reversibly controlled the shuttling mode of the rotaxane in this eight-component network where the ion translocation status was monitored by the naked eye.