六元瓜环与含双苯并咪唑功能基烷烃的自组装模式及晶体结构

以含有双苯并咪唑功能基的烷烃化合物二氯化-1,4-二(2,2’-苯并咪唑基)丁烷(SBB)为客体,普通六元瓜环(Q[6])为主体,利用1H NMR技术、荧光发射光谱和X-单晶衍射实验等考察了主客体的自组装模式.1 H NMR技术结果显示,当主客体的比例为1:1时,在水溶液中,1个Q[6]包结1个客体分子的一端苯并咪唑基团;在结晶固态条件下,X-单晶衍射实验测试结果是Q[6]包结客体分子的烷基链.荧光发射光谱表明,当主客体比例为2:1时,2个Q[6]分别包结1个客体分子的两端苯并咪唑基团形成哑铃型的实体配合物。     

两种部分甲基取代瓜环配合物的晶体结构(英文)

本文报道了2种新的部分甲基取代瓜环配合物的晶体结构,利用X-射线单晶衍射技术表征了2种配合物的结构,在CdCl2溶液中,1,2,4,5-八甲基六元瓜环选择性的包结客体分子1,2-(2,2′-bisbenzimidazolyl)ethanedichloride,形成2∶1的哑铃型主客体包结配合物;而1,2,4-六甲基五元瓜环(HMeQ[5])与钠离子配位形成包结一个水分子的"分子胶囊","分子胶囊"之间通过氢键自组装形成一维的超分子长链。     

七元瓜环与1,7-二(2-苯并咪唑)庚烷的相互作用及自组装

利用~1H NMR法、紫外吸收光谱法、荧光发射光谱法和单晶X射线衍射等方法考察了七元瓜环(Q[7])与氯化1,7-二(2-苯并咪唑)庚烷(SBHt)在酸性溶液中的相互作用过程及组装模式.首先考察了主客体相互作用对客体p Ka的影响,以确定研究主客体相互作用以及组装过程的实验条件.~1H NMR滴定实验结果表明,在水溶液中主客体可形成1∶1和2∶1的主客体包结配合物,当主客体物质的量之比为1∶1时,Q[7]包结SBHt的烷基链,两端苯并咪唑基团处于瓜环端口外侧;当主客体物质的量之比为2∶1时,两个Q[7]分别包结同一SBHt分子的两端苯并咪唑基团,这一实验结果得到荧光发射光谱的佐证.Q[7]与SBHt形成1∶1的主客体包结配合物的晶体结构表明,客体烷基链在瓜环空腔内发生折叠以使其通过离子偶极及氢键与Q[7]有效作用.     

六元瓜环、对称四甲基六元瓜环与2,2'-(1,8-辛烷)-二异喹啉二溴化物的自组装模式

利用核磁共振波谱、 紫外吸收光谱、 荧光光谱和单晶X射线衍射分析等考察了六元瓜环(Q[6])及对称四甲基六元瓜环(TMeQ[6])与2,2'-(1,8-辛烷)-二异喹啉二溴化物的相互作用. 实验结果表明, 客体分子分别与这2种瓜环自组装形成相似的1∶1包结配合物, 但晶体结构分析结果表明两个体系在主客体分子间作用力诱导下形成了不同的空间堆积模式, 其包结常数分别为K_K8-Q[6]=4.18×10⁷ L/mol, K_K8-TMeQ[6]=6.11×10⁷ L/mol.     

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.     

八元瓜环与1,7-二(2-苯并咪唑)-庚烷的超分子自组装

以氯化1,7-二（2-苯并咪唑）-庚烷（SBHt）为客体,八元瓜环（Q[8]）为主体,利用¹H NMR技术、动态光散射实验、荧光发射光谱、紫外吸收光谱详细探索了其在溶液中的相互作用、超分子自组装过程及作用模式. 首先考察了八元瓜环对客体pKa的影响,确定了研究主客体相互作用的条件,并详细探索了主客体的超分子自组装过程及作用模式. 主体Q[8]与客体SBHt相互作用的¹H NMR谱图表明,主客体相互作用自组装形成1：1超分子聚合物. 这一推断得到动态光散射实验、紫外吸收光谱、荧光发射光谱测定结果的证实,并通过紫外吸收光谱、荧光发射光谱确定其表观稳定常数分别为2.79×10⁵ L/mol及2.48×10⁵ L/mol. 而晶体结构测定表明主体Q[8]与客体SBHt自组装形成1：2的简单包结配合物. 导致Q[8]与SBHt在溶液中和固体状态下形成不同自组装结构可能源于瓜环的外壁作用与包结作用竞争所致.     

核磁共振技术对瓜环与苯并咪唑类化合物自组装模式的研究

利用核磁共振技术考察了六、七、八元瓜环与三种苯并咪唑类化合物的相互作用情况,并对瓜环与这类客体相互作用模式及作用机理进行了深入的研究。实验结果表明:三种客体均能与三种瓜环形成主客体配合物,但作用模式及作用比随瓜环的大小而各不相同,六、七元瓜环与客体相互作用形成1∶1的包结配合物,八元瓜环与客体相互作用形成1∶2的包结配合物。     

光谱分析法研究瓜环对苯并咪唑衍生物的分子识别

利用紫外吸收光谱法、荧光光谱法测定了三种苯并咪唑衍生物与六、七、八元瓜环的相互作用,计算出了主客体配合物的稳定常数,并考察了酸度对苯并咪唑衍生物与瓜环相互作用的影响,最后用紫外吸收光谱法测定了瓜环对三种客体化合物的回收率。实验结果表明:在一定的pH范围内,用紫外吸收光谱法、荧光光谱法可以很明显的观察到瓜环与三种客体的相互作用。六元瓜环与客体相互作用形成1∶1的包结配合物,七、八元瓜环与客体相互作用分别形成1.5∶1和1∶2的包结配合物,六、八元瓜环与三种客体相互作用形成的主客体配合物的稳定常数分别在103～104L·mol-1和1011～1012L2·mol-2范围内。瓜环对三种客体的回收率在98%～105%之间。     

八元瓜环与二(2-亚甲基-1,2,3,4-四氢异喹啉)的自组装模式

以用1,2,3,4-四氢喹啉和二溴乙烷合成的二(2-亚甲基-1,2,3,4-四氢异喹啉)的溴化氢酸盐为客体, 八元瓜环为主体, 利用1H NMR技术, 单晶X射线衍射方法以及理论计算等方法, 考察了两者的自组装模式. 1H NMR分析结果表明, 在溶液状态条件下, 不仅每一个八元瓜环分子同时与两个客体分子的芳环部分相互作用, 而且每一个客体分子两端的芳环部分同时与两个八元瓜环分子相互作用, 从而形成一维的自组装超分子链; 而在固体状态下, 每一个八元瓜环也可同时包结两个客体的芳环部分而形成三元的自组装结构, 但八元瓜环包结两个客体形成一独立的三元自组装结构. 利用晶体结构建立模型的计算结果说明, 模拟溶液状态比固体状态条件下的主客体包结更有利于体系能量的降低, 与主客体在溶液中1H NMR实验结果相符.     

水溶性六元瓜环衍生物与1,ω-亚烷基吡啶主客体配合物的~1H NMR及晶体结构

利用1HNMR技术以及单晶X衍射技术考察对称四甲基取代六元瓜环(TMeQ[6])与几种1,ω-亚烷基吡啶阳离子(ω=2,4,6,8,10)客体的相互作用.在这些包结配合物中,TMeQ[6]的端口效应以及空腔效应同时存在,其主客体作用模式随着客体亚烷基碳链长短不一而各不相同.对于客体1,2-二乙基吡啶(Edpy),TMeQ[6]包结Edpy的带正电荷的吡啶环部分,形成一不对称的包结配合物;对于客体1,4-二丁基吡啶(Bdpy),TMeQ[6]选择性包结Bdpy的吡啶环部分或烷基部分存在竞争作用和快速交换;而具有较长碳链的客体1,6-二己基吡啶(Hdpy)和1,8-二丁庚基吡啶(Odpy)与TMeQ[6]通过空腔的疏水作用以及外部的离子-偶极作用形成稳定的类轮烷包结配合物;客体1,10-二癸基吡啶(Ddpy)的两个吡啶环分别被两个TMeQ[6]包结形成哑铃型的包结配合物.     

Host–guest complexes of various cucurbit[n]urils with the hydrochloride salt of 2,4-diaminoazobenzene

The interaction products of normal cucurbit[n]urils (n = 7, 8; Q[7] Q[8]) and a sym- tetramethyl-substituted cucurbit[6]uril derivative (TMeQ[6]) with the hydrochloride salts of 2,4-diaminoazobenzene (g·HCl) were investigated in aqueous solution using ¹H NMR spectroscopy, electronic absorption spectroscopy, as well as single crystal X-ray diffraction. The ¹H NMR spectra analysis established a basic interaction model in which inclusion complexes with a host:guest ratio of 1:1 form for the TMeQ[6] and Q[7] cases, while they form with a host:guest ratio of 1:2 for the Q[8] case. Commonly, the hosts selectively bound to the phenyl moieties of the guests. Absorption spectrophotometric analysis in aqueous solution defined the stability of the host–guest inclusion complexes at pH 3.2. Quantitatively, at this pH, complexes with a host:guest ratio of 1:1—those with smaller hosts TMeQ[6] and Q[7]—formed with logK values between 6 and 7. That with host Q[8] and a host:guest ratio of 1:2 formed with a logK value of 10.8. Single crystal X-ray structures of the inclusion complexes TMeQ[6]–g·HCl and Q[8]–g·HCl showed the phenyl moiety of the guest inserted into the host cavity. This result supports the solution-based ¹H NMR spectroscopic study.     

Host–guest complexes of some cucurbit[n]urils with the hydrochloride salts of some imidazole derivatives

Interaction between the normal cucurbit[n]urils (n = 6,7,8; Q[6], Q[7], Q[8]) and a sym-tetramethyl-substituted cucurbit[6]uril derivative (TMeQ[6]) with the hydrochloride salts of some imidazole derivatives N-(4-hydroxylphenyl)imidazole (g1), N-(4-aminophenyl)imidazole (g2), 2-phenylimidazole (g3) in aqueous solution was investigated by using ¹H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy, as well as by using a single crystal X-ray diffraction determination. The ¹H NMR spectra analysis established a basic interaction model in which inclusion complexes with a host:guest ratio of 1:1 forms for the Q[6]s and Q[7] cases, while with a host:guest ratio of 1:2 form for the Q[8] cases. It was common that the hosts selectively bound the phenyl moiety of the guests. Absorption spectrophotometric and fluorescence spectroscopic analysis in aqueous solution defined the stability of the host–guest inclusion complexes at pH 5.8 with a host:guest ratio of 1:1 form quantitatively as logK values between 4 and 5 for the smaller hosts Q[6 or 7]s, while with a host:guest ratio of 1:2 form quantitatively as logK values between 11 and 12 for the host Q[8]. Two single crystal X-ray structures of the inclusion complexes TMeQ[6]-g2 · HCl and TMeQ[6]-g3 · HCl showed the phenyl moiety of these two guests inserted into the host cavity, which supported particularly the ¹H NMR spectroscopic study in solution.     

六、七、八元瓜环与苯胺系列衍生物的相互作用

利用紫外吸收光谱、荧光光谱以及¹H NMR方法详细考察了六、七、八元瓜环(Q[6], Q[7], Q[8])与苯胺系列衍生物客体的相互作用和体系pH对其作用的影响. 实验结果表明, 3种瓜环与苯胺系列衍生物客体的相互作用强弱、作用比例以及作用模式与体系的酸度密切相关: 在“高”或“低”pH条件下, 未观察到瓜环与这些客体的明显作用; 在介于“高”与“较高”或“低”与“较低”的pH范围, 瓜环与这些客体发生相互作用, 形成1∶1的包结配合物; 而在介于“较高”与“较低”的pH范围, 瓜环与这些客体发生相互作用, 可形成1∶2的包结配合物. 对于不同的瓜环-客体作用体系, 相应的pH范围各不相同. 本文利用简便的实验方法, 测试了这些pH值及其范围. 根据测定的结果, 结合瓜环以及客体的结构特征, 对体系主客体在不同的酸度区域表现出的不同作用模式进行了探讨.     

七、八元瓜环对萘二胺异构体相互作用的考察

利用紫外吸收光谱、荧光光谱以及¹H NMR方法考察了七、八元瓜环(Q[7], Q[8])与1,8-萘二胺(g1), 2,3-萘二胺(g2), 1,5-萘二胺(g3)的相互作用. 实验结果表明: Q[7]与客体g1发生端口作用, 作用比为1∶1; Q[7]与客体g2, g3相互作用也形成1∶1的包结配合物. Q[8]与三种客体相互作用情况各不相同, 除Q[8]与客体g2相互作用形成1∶2的包结配合物; Q[8]与客体g1或g3可发生相互作用, 形成溶解性较差的作用产物, 其表观相互作用的比例为1∶1. 考察溶液酸度对主客体相互作用的影响还表明: 当pH大于某一值之后, 如Q[7]主客体体系, pH大于6.0; Q[8]主客体体系, pH大于12.0, 用光谱方法观察不到瓜环与客体的相互作用. Q[7], Q[8]为主体的上述主客体作用产物分别与金刚烷胺盐酸盐、1,10-癸二胺盐酸盐的竞争反应结果表明, 已作用的萘二胺异构体容易被所选用的竞争客体所取代, 只有g2与Q[8]形成的包结配合物被1,10-癸二胺盐酸盐部分取代.     

八元瓜环与常山碱的相互作用模式

利用紫外吸收光谱、 荧光光谱、 核磁共振氢谱及红外光谱等方法考察了八元瓜环(Q[8])对常山碱(Feb)的包结作用; 采用紫外吸收光谱法研究了Q[8]对Feb理化性质的影响及不同pH条件下Q[8]/Feb包合物溶液中Feb的释放及Q[8]/Feb包合物在人工肠液和人工胃液中的释放. 结果表明, 在pH=1.2的盐酸介质中, Q[8]与Feb可形成摩尔比1∶1的稳定主客体包合物, 结合常数为4.20×10 ⁴ L/mol. 在pH=1.2(人工胃液的pH值)时, Feb可与Q[8]形成稳定包合物; 在pH=6.8(人工肠液的pH值)时, Q[8]/Feb包合物可释放出单纯的游离Feb. 因此, Q[8]可作为Feb的一种潜在药物载体为减轻Feb呕吐副反应提供借鉴.     

Highly Selective Separation of Minimum‐Boiling Azeotrope Toluene/Pyridine by Nonporous Adaptive Crystals of Cucurbit[6]uril

The production of high purity toluene and pyridine is of significance in both industrial production and synthetic chemistry. The present protocols available to separate toluene/pyridine mixtures are several energy‐intensive distillation methods, which are not environmentally friendly and cost‐effective. Herein, we provide an energy‐efficient and simple adsorptive separation protocol using nonporous adaptive crystals of cucurbit[6]uril ( Q[6] ). Q[6] crystals separate pyridine from toluene/pyridine mixtures with nearly 100 % purity. Furthermore, removal of the guest from guest‐loaded Q[6] leads to the guest‐free cucurbit[6]uril, which can be recycled without losing performance.     

Supramolecular assemblies of cucurbit[n]urils and 4-aminopyridine controlled by cucurbit[n]uril size (n = 5, 6, 7 and 8)

The binding interactions between 4-aminopyridine (4-AP) and a series of cucurbit[n]urils (Q[5], Q[6], TMeQ[6], Q[7], Q[8]) have been studied using ¹H NMR spectroscopy, UV–vis absorption spectroscopy, isothermal titration calorimetry (ITC) and X-ray crystallography. The data indicates that the Q[5]@4-AP complex exhibits exo binding, which is not observed in the other four host-guest complexes. Furthermore, X-ray crystallography clearly reveals how the Q[n]s bind with 4-AP to form complexes, for example Q[5] forms an outer-surface complex, whilst Q[6], TMeQ[6] and Q[7] formed 1:1 host and guest type complexes, and Q[8] formed a stable 1:2 ternary complex due to its large cavity, which can accommodate two 4-AP molecules.     

Supramolecular assembly of cucurbit[6]uril and N-butyl-4-pyrrolidinopyridine

The nature of the supramolecular host–guest complex involving 4-pyrrolidinopyridine (BuPC4) and cucurbit[6]uril (Q[6]) has been investigated by NMR and UV spectroscopy, MALDI-TOF mass spectrometry, X-ray crystallography and isothermal titration calorimetry. The results revealed that the alkyl chain of the guest BuPC4 is located inside the cavity of the Q[6] host, whereas the other section of the BuPC4 guest remains outside of the portal.     

Cucurbit[n]urils-induced room temperature phosphorescence of quinoline derivatives

The cucurbit[7,8]urils (Q[7] and Q[8])-induced room temperature phosphorescence (RTP) of quinoline and its derivatives were firstly found in the cucurbit[n]urils chemistry. The luminophores (quinolines) and their RTP are affected by the concentration of different Q[n]s, heavy metal ions and amounts, and pH. The RTP lifetime of the luminophore has been investigated. In presence of Na₂SO₃, the cation Tl⁺ led to stronger Q[n]-induced RTP, while the RTP lifetimes of luminophore/Q[7 or 8]/KI were generally longer than that of luminophore/Q[7 or 8]/TlNO₃, the RTP lifetimes of these systems were between 0.18 and 47.4 ms. Contrary to the stable 1:2 Q[8]:guest ternary inclusion complexes at lower pHs, as suggested by ¹H NMR, electronic absorption and fluorescence spectroscopy, low Q[8]-induced room temperature phosphorescence was observed. However, at higher pHs, high intensity of cucurbit[n]urils-induced room temperature phosphorescence of these quinoline derivatives were observed, and a 1:1 Q[8]:guest inclusion complex was formed. Investigations of dependence of RTP intensity on concentration of Q[n] revealed that the highest intensity of the Q[n]-induced RTP was observed at a low mole ratio of host:guest, which is closed to 1:1. It was presumably resulted from the strong interaction of Q[n] and these guests due to the combined hydrophobic cavity interaction and the hydrophilic portal interaction of the cucurbit[n]urils with the nitrogen heterocycles guest.