类水滑石材料主客体插层结构的构筑及特性的理论研究

因主体层板和层间客体具有丰富的可调性, 类水滑石材料(LDHs)在催化、 吸附、 生物医药及光、 电、 磁等方面展现出了广阔的应用前景. 近年来理论研究已成为揭示LDHs微观结构和性质的重要手段, 本文系统综述了LDHs材料主体结构、 客体结构以及主客体相互作用3个方面的理论研究工作进展, 及其在作为光驱动催化剂方面应用的理论研究. 从主体元素构成、 元素比例、 电荷分布、 拓扑结构转变、 能带结构、 态密度、 层间阴离子组成、 离子交换性能、 主客体作用力、 能量性质及光催化性能等方面, 在原子、 电子尺度上揭示了LDHs材料结构-性能之间的构效关系, 为以其为材料平台构筑一系列基于超分子插层结构主客体间相互作用的新型功能材料、 扩展材料的功能性提供了丰富的理论信息和有益指导.     

基于柱[5]芳烃主客体包结构筑分子响应型超分子水凝胶

主客体相互作用是在水溶液中与大环主体分子形成稳定的包结物的理想驱动力.以功能化的苯并咪唑衍生物为客体(M),水溶性柱[5]芳烃为主体构建了一种分子响应型超分子水凝胶.通过1H NMR, 2D NOESY和扫描电子显微镜(SEM)研究了水凝胶的成凝胶机理.有趣的是,主客体包结作用、柱[5]芳烃间有序的"外腔"π-π相互作用和分层堆积对于获得超分子水凝胶是必不可少的,非共价键相互作用的动态可逆性使凝胶体系对温度变化/化学刺激产生响应.此外,加入竞争性客体己二腈(ADN)/百草枯(PQ)后,柱[5]芳烃基水凝胶可转化为溶胶.因此,该超分子水凝胶可以选择性识别有机分子.     

基于柱[5]芳烃主客体包结构筑分子响应型超分子水凝胶（英文）

主客体相互作用是在水溶液中与大环主体分子形成稳定的包结物的理想驱动力.以功能化的苯并咪唑衍生物为客体(M),水溶性柱[5]芳烃为主体构建了一种分子响应型超分子水凝胶.通过1H NMR, 2D NOESY和扫描电子显微镜(SEM)研究了水凝胶的成凝胶机理.有趣的是,主客体包结作用、柱[5]芳烃间有序的"外腔"π-π相互作用和分层堆积对于获得超分子水凝胶是必不可少的,非共价键相互作用的动态可逆性使凝胶体系对温度变化/化学刺激产生响应.此外,加入竞争性客体己二腈(ADN)/百草枯(PQ)后,柱[5]芳烃基水凝胶可转化为溶胶.因此,该超分子水凝胶可以选择性识别有机分子.     

氨基甲酸酯型α-猪去氧胆酸分子钳对分子的识别性能研究

用差紫外光谱滴定法考察了新型猪去氧胆酸分子钳1~6对苯胺、对甲氧基苯胺、对硝基苯胺等中性分子的识别性能,测定了主客体间的结合常数(Ka)和自由能变化(△G°)。结果表明,分子钳主体对所考察的客体分子显示良好的识别作用,主客体间形成1∶1型超分子配合物,最大结合常数可达3123.46L.mol-1,识别作用的主要推动力为氢键,范德华力等的协同作用。讨论了主体与客体的识别模式以及客体间形状、大小匹配和几何互补等因素对形成超分子配合物的影响,并利用核磁共振氢谱与计算分子模拟作为辅助手段对实验结果与现象进行了解释。     

瓜环与含羟基功能基二胺包结配合物的晶体结构及相互作用的研究

合成并表征了含羟基功能基的二胺1,3-二(2-氨基苯氧基)-2-丙醇(客体). 利用X射线衍射方法研究了客体与八元瓜环Q[8]所形成包结配合物的晶体结构. 结果表明主客体间形成了1∶2的包结配合物, 两个客体分子分别从瓜环的两个端口进入瓜环内腔, 在腔内两个客体分子中的苯环间存在着π-π相互作用. 利用1H NMR技术及紫外-可见吸收光谱对主客体间的相互作用进行考察, 所得结果与晶体结构吻合.     

邻-甲氧基苯酚和α-,β-环糊精包合现象的理论与实验研究

通过紫外可见光谱法考察了水溶液中邻-甲氧基苯酚(o-Mop)和α-与β-环糊精(CD)的分子间相互作用, 利用Hildebrand-Benesi方程给出了两个包合物的稳定常数(K_s). 采用半经验PM3方法研究了α-,β-CD和o-Mop及其类似物苯酚(Phe)、丁香酚(Eug)之间的包络作用, 阐述了这些主客体包合作用过程中体系能量随主客体相对位置改变而变化的细节, 据此推断出主-客体包合物可能的分子结构, 计算了包合物的稳定化能(ΔE_s). 研究结果表明, 本文所选主客体体系而言, 当客体和同一种主体分子作用时, 超分子包合物的ΔE_s随着客体分子苯环上取代基团数目的增多而增加. 基于PM3方法优化得到的主-客体包合物在真空中的分子结构和通过实验方法在水溶液中测定的结构一致.     

七、八元瓜环与两种含香豆素单元的紫精衍生物的相互作用

合成了两个含有香豆素单元的紫精衍生物(简称[XDS-3CMV],[XDS-6CMV]).利用1H NMR,ESI-MS,UV-Vis以及荧光光谱分析方法考察了七、八元瓜环CB[n](n=7,8)与客体分子[XDS-3CMV],[XDS-6CMV]之间的相互作用.结果显示,两种客体均可与CB[n](n=7,8)分别形成稳定的包结配合物,烷基链长度以及瓜环空腔尺寸的差异影响主客体相互作用的模式.其中七元瓜环与两种客体分子的紫精部分作用形成1∶1的包结配合物;八元瓜环可以与折叠成U型结构的[XDS-6CMV]分子形成1∶1的包结物,而与[XDS-3CMV]分子则形成超分子聚合物.     

基于主客体作用构筑的聚集诱导发光型超分子组装体 在生物医用领域的研究进展

主客体相互作用是超分子自组装过程中最重要的作用方式之一,常被用于构建多功能超分子材料.基于主客体相互作用,利用具有聚集诱导发光性质的大环主体分子或客体分子作为自组装基元,构筑具有聚集诱导发光效应的超分子体系,并将其应用于药物递送、细胞成像、生物传感等生物领域,已成为超分子化学的研究热点.从超分子组装体的发光效应分别源于主体分子和客体分子两方面,介绍了近五年来以环糊精、杯芳烃、葫芦脲、柱芳烃及其它大环为主体化合物,基于主客体作用构筑的聚集诱导发光超分子组装体,并对其在生物医用领域的研究进展进行了简要综述.     

基于主客体识别作用的光控智能超分子体系的研究进展

利用主客体识别作用赋予材料智能化是目前智能材料研究的一个新方向.通过光可以使客体分子发生可逆的结构改变,如偶氮苯可逆的光致顺反异构,结合环糊精主体分子和客体分子之间可逆形成包结物的能力,可以利用光来设计光控的智能超分子体系.基于上述环糊精和客体分子之间的光控制的主客体识别作用,本文从有机小分子、聚合物和表面三个方面综述了近年来基于主客体识别作用的光控智能超分子体系的研究工作,并对该领域的研究前景进行了展望.     

新型Schiff碱分子钳对中性分子的识别性能研究

采用差紫外光谱法考察了3种新型Schiff碱分子钳对一系列二苯甲酮、芳香二胺的识别性能.测定了主客体间的结合常数(Ka)和自由能变化(ΔG0).结果表明,分子钳对所考察的客体显示良好的识别作用,主客体间形成1:1型超分子配合物.讨论了识别作用的推动力与形状、大小匹配和几何互补等因素对形成主客体配合物的影响,并利用核磁氢谱与计算机模拟作为辅助手段对主要的实验结果与现象进行了解释.     

Recognition of N‐Alkyl and N‐Aryl Acetamides by N‐Alkyl Ammonium Resorcinarene Chlorides

N‐Alkyl ammonium resorcinarene chlorides are stabilized by an intricate array of intra‐ and intermolecular hydrogen bonds that leads to cavitand‐like structures. Depending on the upper‐rim substituents, self‐inclusion was observed in solution and in the solid state. The self‐inclusion can be disrupted at higher temperatures, whereas in the presence of small guests the self‐included dimers spontaneously reorganize to 1:1 host–guest complexes. These host compounds show an interesting ability to bind a series of N‐alkyl acetamide guests through intermolecular hydrogen bonds involving the carbonyl oxygen (C?O) atoms and the amide (NH) groups of the guests, the chloride anions (Cl^?) and ammonium (NH₂⁺) cations of the hosts, and also through CH ??? π interactions between the hosts and guests. The self‐included and host–guest complexes were studied by single‐crystal X‐ray diffraction, NMR titration, and mass spectrometry.     

Construction of supramolecular polymers with alternating alpha-, beta-cyclodextrin units using conformational change induced by competitive guests

Supramolecular polymers having alternating alpha- and beta-cyclodextrin (CD) units have been prepared by using conformational change induced by competitive guests. Although each CD unit does not form intermolecular complexes, a mixture of an alpha-CD derivative and a beta-CD derivative formed intermolecular complexes to give supramolecular polymers having alternating CD units. This is the first example of construction of supramolecular polymers with alternating alpha-, beta-cyclodextrin units.     

Manifesting Subtle Differences of Neutral Hydrophilic Guest Isomers in a Molecular Container by Phase Transfer

Achieving strong host–guest interactions between synthetic hosts and hydrophilic guests in solution is challenging because solvation effects overwhelm other effects. To resolve this issue, we transferred complexes of cucurbit[7]uril (CB[7]) and monosaccharides to the gas phase and report here their intrinsic host–guest chemistry in the absence of solvation effects. It was observed that effective host–guest interactions in the gas phase mediated by ammonium cations allow the differentiation of the monosaccharide isomers in complex with CB[7] upon vibrational excitation. The potential of the unique observation was extended to a quantitative supramolecular analytical method for the monosaccharide guests. The combination of host–guest chemistry and phase transfer presented in this study is an effective approach to overcome current limitations in supramolecular chemistry.     

The complexation of two different ammonium ions with resorcarenes in protic solvent medium investigated by electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry

The complexations of two ammonium ions (guests) with two resorcarenes (hosts) were investigated using electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry. Although the two guests and the two hosts were noticeably similar, the quantity of the corresponding supramolecular complexes formed varied significantly due to the differences in host conformations and guest ability to form non-covalent interactions.     

Selectivity in supramolecular host-guest complexes

The background of possible selectivity-affinity correlations and their limitations is reviewed, with typical crown ether and cryptand complexes, ionic associations, hydrogen bonded complexes and complexes driven by van der Waals, stacking or hydrophobic interactions, with some additional topics including associations based on metal coordination as supplementary material. This tutorial review is addressed to students and researchers interested in molecular recognition, and relates to the design of sensors, of discriminators for separation processes, of supramolecular devices and of drug compounds. A theoretical analysis of selectivity in supramolecular host-guest complexes, defined as a difference in binding free energies for structurally related guests, as a function of total binding free energy shows that for certain types of intermolecular interactions one may observe a correlation between selectivity and affinity. Such correlation fails however if the selectivity is due to additional interactions at a secondary binding sites, which is expected in complexes with anisotropic guest molecules. Several clear examples of theoretically expected selectivity-affinity correlations are found. The influence of reaction conditions on the experimentally observed selectivity, defined as a difference in complexation degrees with different guests in the presence of added receptor, is illustrated. The importance of often neglected solvent effects on selectivity is exemplified with ionophore and hydrogen bonded complexes.     

Hierarchical self-assembly of noncovalent amphiphiles

Amphiphiles defined by noncovalent inclusion complexes between an alkylated beta-cyclodextrin and PEG-conjugated guests assemble into higher-ordered structures whose thermodynamic stability reflects that of the defining intermolecular interactions.     

Effect of electron donor-acceptor interaction on the thermal stability of supramolecular side chain liquid crystalline polymers based on poly(3-carboxypropylmethylsiloxane)

Supramolecular side chain liquid crystalline polymers were prepared from poly(3-carboxypropylmethylsiloxane) (PSI100) and azobenzene-based derivatives through intermolecular hydrogen bonding between the carboxylic acid groups of PSI100 and the imidazole rings in the azobenzene-based derivatives. The presence of H-bonding was confirmed using FTIR spectroscopy. The polymeric complexes behave as liquid crystalline polymers and exhibit nematic mesophases identified on the basis of the observation of Schlieren textures. The mesogenic behaviour of these complexes was studied by polarizing optical microscopy and X-ray diffraction. The thermal behaviour of the complexes was investigated by differential scanning calorimetry. On increasing the spacer length, the transition temperatures initially increase. A further increase in spacer length, however, leads to a decrease in the transition temperatures. The electron donor-acceptor interaction between unlike mesogenic units in supramolecular copolymeric complexes helps to stabilize the mesophase.     

Effect of electron donor-acceptor interaction on the thermal stability of supramolecular side chain liquid crystalline polymers based on poly(3-carboxypropylmethylsiloxane)

Supramolecular side chain liquid crystalline polymers were prepared from poly(3-carboxypropylmethylsiloxane) (PSI100) and azobenzene-based derivatives through intermolecular hydrogen bonding between the carboxylic acid groups of PSI100 and the imidazole rings in the azobenzene-based derivatives. The presence of H-bonding was confirmed using FTIR spectroscopy. The polymeric complexes behave as liquid crystalline polymers and exhibit nematic mesophases identified on the basis of the observation of Schlieren textures. The mesogenic behaviour of these complexes was studied by polarizing optical microscopy and X-ray diffraction. The thermal behaviour of the complexes was investigated by differential scanning calorimetry. On increasing the spacer length, the transition temperatures initially increase. A further increase in spacer length, however, leads to a decrease in the transition temperatures. The electron donor-acceptor interaction between unlike mesogenic units in supramolecular copolymeric complexes helps to stabilize the mesophase.     

Binding propensity and selectivity of cationic,anionic, and neutral guests with model hydrophobic hosts: A first principles study

Computations play a critical role in deciphering the nature of host–guest interactions both at qualitative and quantitative levels. Reliable quantum chemical computations were employed to assess the nature, binding strength, and selectivity of ionic, and neutral guests with benzenoid hosts. Optimized complex structures reveal that alkali and ammonium ions are found to be in the hydrophobic cavity, while halide ions are outside, while both complexes elicit substantial binding energy. The origin of the selectivity of host toward the guest has been traced to the interaction and deformation energies, and the nature of associated interactions is quantified using energy decomposition and the Quantum Theory of Atoms in Molecules analyses. While the larger hosts lead to loosely bound complexes, as assessed by the longer intermolecular distances, the binding strengths are proportional to the size of the host systems. The binding of cationic complexes is electrostatic or polarization driven while exchange term dominates the anionic complexes. In contrast, dispersion contribution is a key in neutral complexes and plays a pivotal role in stabilizing the polyatomic complexes.