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.     

瓜环[n](n=6～8)与盐酸丁咯地尔的相互作用

利用1HNMR技术、电喷雾质谱、红外光谱及紫外吸收光谱等手段研究了瓜环[n](n=6～8)与盐酸丁咯地尔的相互作用.实验结果表明,盐酸丁咯地尔与3种瓜环具有不同的相互作用,主-客体配合物的作用模式随着瓜环大小的不同而各不相同.其中,瓜环[6]与盐酸丁咯地尔的相互作用非常弱,而瓜环[7]和瓜环[8]则都将盐酸丁咯地尔分子中的吡咯环及其相邻的2个碳全部包结进去,形成了包结比为1:1的对称包结配合物.通过紫外吸收光谱法计算得到瓜环[7]和瓜环[8]与盐酸丁咯地尔分子的包结常数在102～103L/mol范围内,说明瓜环对盐酸丁咯地尔具有潜在的药物缓释作用.     

瓜环{Q[n]}与染料碱性嫩黄O相互作用的研究

利用1H NMR和UV-vis研究了瓜环{Q[n](n=6,7)}与染料碱性嫩黄O(BO)的相互作用及其包结比【n{Q[n]}∶n(BO)】,结果表明,BO能穿过Q[7]空腔形成2∶1的包结配合物,能与Q[6]以端口的形式相互作用,配位比1∶1。     

瓜环/麦穗宁超分子体系的形成对麦穗宁的pK_a、溶解性及抑菌活性的影响

利用紫外吸收光谱法、等温滴定量热法、1H NMR法等研究了麦穗宁与瓜环Q[n](n=6,7,8)的超分子相互作用,讨论了瓜环/麦穗宁超分子体系的形成对麦穗宁的pKa及抑菌活性的影响.实验结果表明,麦穗宁与Q[n](n=6,7,8)均形成1∶1的主客体配合物,瓜环/麦穗宁超分子体系的形成使麦穗宁的pKa发生了明显移动,且对麦穗宁有助溶作用;Q[6]、Q[7]的加入减弱了麦穗宁对小麦赤霉的抑菌活性,而Q[8]的加入则增强了麦穗宁对小麦赤霉的抑菌活性.     

核磁共振法研究瓜环[n]对盐酸哌甲酯的手性识别

利用核磁共振(NMR)技术研究了瓜环[n](n=7,8)对外消旋盐酸哌甲酯的手性识别。研究结果显示,盐酸哌甲酯对映异构体与瓜环形成包合物后,其质子的化学位移移动方向和幅度不同。同时,手性碳附近的某些原子所对应的吸收峰裂分为两组信号,这两组信号分别对应盐酸哌甲酯的两个对映体。说明两个对映体与瓜环形成了作用模式不同的超分子包结物,从而使对映体能够区分开来,即非手性的瓜环将手性盐酸哌甲酯区别开来,实现了瓜环对苏式哌甲酯两个对映体的快速手性识别。     

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。     

瓜环与喹啉衍生物包结配合行为研究

利用¹H NMR以及荧光技术研究了六、七、八元瓜环与2-苯基喹啉、N-正丙基溴化异喹啉、3-氨基喹啉及7,8-苯并喹啉的相互作用.两种方法的考察结果均表明,2-苯基喹啉能与这3种瓜环发生相互作用,其中六、七元瓜环与2-苯基喹啉形成1∶1的稳定包结配合物,包结常数分别为1.6×10⁴和3.2×10³L/mol.八元瓜环能与2-苯基喹啉形成1∶2包结物.¹H NMR结果还表明,3种瓜环均能与N-正丙基溴化异喹啉相互作用,其化学计量比均为1∶2;七元瓜环与7,8-苯并喹啉相互作用,化学计量比约为1∶1.荧光法也表明八元瓜环能与N-正丙基溴化异喹啉、3-氨基喹啉及7,8-苯并喹啉发生相互作用,并且荧光强度随瓜环浓度增加而下降,其化学计量比为1∶2.同时,讨论了上述主客体包结配合物的作用模式.     

葫[n]环联脲与重氮氟硼酸盐的包合作用研究

葫[n]环联脲(简称CB[n],n=5,6,7,8,10)是一类新型的笼状大环主体分子[1],他们能够与烷基胺、染料以及其他一些有机分子形成包结配位,而且还能与金属离子以及金属簇离子形成超分子配合物.我们通过核磁以及紫外的方法首次考察了葫[n]环联脲(n=5,6,7,8)与对甲苯重氮氟硼酸盐(A)及联苯二重氮氟硼酸盐(B)的包合行为,并根据非线性最小二乘法曲线拟合求得配位常数.     

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.     

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^1HNMR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．     

七、八元瓜环对盐酸雷尼替丁的包合作用及缓释性能

研究了七元瓜环(Q[7])和八元瓜环(Q[8])与盐酸雷尼替丁(RH)的包合作用及包合物的体外药物缓释性能.采用紫外-可见光谱法测定了体系的包合比、包合稳定常数和药物累积释放度;用1H NMR技术考察了体系主-客体的包合作用.结果表明,Q[7]和Q[8]与RH在酸性及中性条件下均能发生1∶1包合作用,包合稳定常数分别为1.21×104和2.06×104 L/mol;在碱性条件下则不发生包合作用.原药RH,Q[7]-RH及Q[8]-RH包合物在人工胃液(pH=1.2)中的60 min累积释放度分别为89.1%,56.6%和38.4%;而在人工肠液(pH=6.8)中三者的60 min累积释放度分别为90.2%,58.7%和38.0%.实验结果表明,Q[7]及Q[8]包合对RH有明显的体外缓释作用.     

Bromination of N-phenyloxypropyl-N'-ethyl-4,4'-bipyridium in cucurbit[8]uril molecular reactor

CB[n](n=6-8) is a family of synthetic macrocyclic host molecules composed of n glycoluril units, which can be employed as molecular reactor. N-phenyloxypropyl-N'-ethyl-4,4'-bipyridium (1) was designed to form a host-guest inclusion complex with CB[n](n=6-8), subsequently, the bromination reaction of 1 and its corresponding inclusion complexes was investigated in this work. In the case of 1/CB[8], the folded including mode is quite helpful to acquire 1-bormination product completely through intramolecular charge transfer (ICT), and CB[8] can provide a safe bromination environment for 1.     

吡啶基咪唑[4,5-f]1,10-菲咯啉合成、表征及与瓜环作用的光谱学考察

设计合成了2个吡啶基菲咯啉衍生物2-(3-吡啶基)咪唑[4,5-f]1,10-菲咯啉(G1)和2-(4-吡啶基)咪唑[4,5-f]1,10-菲咯啉(G2),通过元素分析、质谱和核磁共振氢谱对其结构进行了表征。 利用紫外吸收光谱和荧光光谱法考察了所合成化合物与六元瓜环Q[6]、七元瓜环Q[7]的相互作用,以及体系pH值对主-客体相互作用的影响。 在酸性条件下,Q[6]、Q[7]与Gl以及Q[6]与G2均发生包合形成1∶1的包合物,并有荧光增敏作用;Q[7]与G2作用形成1∶2包合物,且对G2有荧光猝灭作用;Q[6]、Q[7]与G1的包合常数分别为3.00×104和1.86×104 L/mol;Q[6]、Q[7]与G2的包合常数分别为1.64×104和1.01×103 L/mol。 随着体系酸性减弱,瓜环与客体作用减弱,在中性条件下,瓜环未与客体发生包合作用。     

葫[n]环联脲(n=5,6,7,8)与两种重氮氟硼酸盐的包合作用研究

用核磁共振氢谱和紫外-可见光谱滴定法考察了葫[n]环联脲(Cucurbit[n]uril,n=5,6,7,8)与对甲苯重氮氟硼酸盐和4,4′-联苯二重氮氟硼酸盐的配位情况,并用曲线拟合求得形成的包结配合物的稳定常数.结果表明,不同空腔的葫[n]环联脲对不同尺寸的重氮氟硼酸盐具有很显著的选择性包结作用.在相同条件下,与葫[6]环联脲相比,葫[7]环联脲更易于容纳苯环.同时,随着酸性的增强,葫[n]环联脲上的脲羰基质子化程度加大,使得其配位能力有所减弱.     

Host-guest chemistry and light driven molecular lock of Ru(bpy)(3)-viologen with cucurbit[7-8]urils

Host-guest chemistry and photoinduced electron-transfer processes have been studied in the systems containing Ru(bpy)3 complex covalently linked to viologen as a guest molecule and cucurbit[n]urils (n = 7, 8) as host molecules in aqueous solution. The Ru(bpy)3-viologen complex, [Ru(2,2'-bipyridine)2(4-(4-(1'-methyl-4,4'-bipyridinediium-1-yl)butyl)-4'-methyl-2,2'-bipyridine)]Cl4 (denoted as Ru2+-MV2+, 1) was shown to form stable 1:1 inclusion complexes with cucurbit[7]uril (CB[7]) and cucurbit[8]uril (CB[8]). The binding modes are slightly different with CB[7] and CB[8]. CB[7] preferentially binds to part of the viologen residue in 1 together with the butyl chain, whereas CB[8] preferentially encloses the whole viologen residue. Photoinduced intramolecular electron transfer from the excited-state of the Ru moiety to MV2(+) which is inserted into the cavity of the CBs occurred. Long-lived charge-separated states Ru3(+)-MV(+*) were generated with the lifetimes of 280 ns with CB[7] and 2060 ns with CB[8]. This shows that CBs can slow down the charge recombination within supramolecular systems, and the difference in lifetimes seems to be due to the difference in binding modes. In the presence of a sacrificial electron donor triethanolamine, light-driven formation of a dimer of MV(+*) inside the CB[8] cavity was observed. This "locked" molecular dimer can be "unlocked" by molecular oxygen to give back the original form of the molecular dyad 1 with the MV2(+) moiety inserted in the cavity of CB[8]. The processes could be repeated several times and showed nice reversibility.     

The cucurbit[n]uril family: prime components for self-sorting systems

We determined the values of Ka for a wide range of host-guest complexes of cucurbit[n]uril (CB[n]), where n = 6-8, using 1H NMR competition experiments referenced to absolute binding constants measured by UV/vis titration. We find that the larger homologues--CB[7] and CB[8]--individually maintain the size, shape, and functional group selectivity that typifies the recognition behavior of CB[6]. The cavity of CB[7] is found to effectively host trimethylsilyl groups. Remarkably, the values of Ka for the interaction of CB[7] with adamantane derivatives 22-24 exceeds 10(12) M(-1)! The high levels of selectivity observed for each CB[n] individually is also observed for the CB[n] family collectively. That is, the selectivities of CB[6], CB[7], and CB[8] toward a common guest can be remarkably large. For example, guests 1, 3, and 11 prefer CB[8] relative to CB[7] by factors greater than 10(7), 10(6), and 3000, respectively. Conversely, guests 23 and 24 prefer CB[7] relative to CB[8] by factors greater than 5100 and 990, respectively. The high levels of selectivity observed individually and collectively for the CB[n] family renders them prime components for the preparation of functional biomimetic self-sorting systems.     

Determination of the purity of cucurbit[n]uril (n = 7, 8) host samples

The formation of highly stable inclusion complexes in aqueous solution between the organometallic cobaltocenium cation (Cob(+)) and the hosts cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) was used to develop a simple method, based on UV-vis titrations, to assay the purity of samples of these two hosts. The equilibrium association constant (K) of the Cob(+)@CB7 complex had been previously reported by our group as 5.7 × 10(9) M(-1) at 25 °C in 50 mM sodium acetate medium. In this work, we determine a K value of 1.9 × 10(8) M(-1) at 25 °C in the same medium for the Cob(+)@CB8 complex. The high stability of these complexes and their decreased molar absorptivity coefficients (at 261 nm), compared to that for free Cob(+), lead to straightforward titration plots when graphing absorbance versus concentration of added CB7 (or CB8) host, at constant Cob(+) concentration.     

The formation of cucurbit[n]uril (n = 6, 7) complexes with amino compounds in aqueous formic acid studied by capillary electrophoresis

For analytes involved in dynamic equilibrium processes, capillary electrophoresis is a powerful method of determining binding constants. In this work, the complex formation between cucurbit[n]uril (CB[n] n = 6, 7) and some amino compounds was studied by capillary electrophoresis in aqueous formic acid (65% v/v). Four groups of positional and structural isomers (o, m, p-methylanilines; m, p-nitroanilines; benzidine and o-tolidine; alpha, beta-naphthylamines and 1,5-diaminonaphthalene) were selected as model compounds for study of their host-guest inclusion complexation. The interactions between CB[n] (n = 6, 7) and the model compounds were also investigated using a molecular modeling method. The results indicate that the interactions of the compounds with CB[n] (n = 6, 7) are strongly affected by the position of the substituent(s) on the aromatic ring and the ion-dipole interaction between guest molecule and CB. Furthermore, the type and the concentration of CBs on the separation and migration behavior of the amino compounds were also studied.