八元瓜环对氯化矢车菊素溶解性、稳定性及抗氧化性的影响

采用核磁共振氢谱(¹H NMR)、 红外光谱及紫外吸收光谱等方法考察了八元瓜环(Q[8])对氯化矢车菊素(Cy)的包结作用. 结果表明, 在pH=0.8的盐酸介质中, Q[8]可与Cy形成摩尔比为1:1的主客体配合物, 紫外吸收光谱法测得的主-客体结合常数为1.51×10⁶ . 相溶解度研究结果表明, Q[8]能使饱和Cy溶液的溶解度增大, 当Q[8]浓度为100 μmol/L时, 可使Cy的溶解度增大12.21倍. 紫外吸收光谱随时间变化结果表明, 在较为稳定存在形态及相同实验条件下, Q[8]/Cy溶液比Cy溶液的稳定性提高了2.58倍. 抗氧化性实验结果表明, Q[8]/Cy包合物和Cy均表现出较好的抗氧化活性.     

七元瓜环对阿糖胞苷稳定性的影响

研究了七元瓜环(Q[7])与抗癌药物阿糖胞苷(Ara-C)的不同质子化存在形式之间的超分子相互作用, 探讨了超分子包合作用对药物电离平衡常数及药物稳定性的影响. 结果表明, Q[7]使得Ara-C的pK_a降低了约0.3个单位, Q[7]与Ara-C的2种存在形式(Ara-C⁺及Ara-C)均可形成1∶1的主客体包结配合物, Ara-C以其嘧啶环进入Q[7]空腔, 而核糖环位于瓜环端口发生相互作用; Q[7]与Ara-C作用后对药物起到保护性载体的作用, 从而提高了药物的稳定性.     

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.     

六元瓜环与二氯化-1,8-二(2-苯并咪唑基)辛烷的自组装模式

采用¹H NMR、 荧光光谱和紫外吸收光谱法考察了主体六元瓜环与合成客体二氯化-1,8-二(2-苯并咪唑基)辛烷的自组装模式. 结果表明, 六元瓜环能与二氯化-1,8-二(2-苯并咪唑基)辛烷发生相互作用, 瓜环包结客体分子的苯并咪唑基团, 烷基链置于瓜环端口外侧. 自组装模式与主客体的摩尔比密切相关. 当主客体的摩尔比为1:1时, 1个瓜环包结客体分子的一端苯并咪唑基团形成棒槌形的包结配合物; 当主客体的摩尔比为2:1时, 2个瓜环分别包结客体分子的两端苯并咪唑基团形成哑铃型的主客体包结配合物.     

十二甲基六元瓜环包结1,4-二烷噁的晶体结构

合成了全甲基取代六元瓜环(Me_(12)Q[6])与1,4-二噁烷的包结配合物并生长了晶体,通过单晶X-射线衍射方法进行了表征;该配合物形成了以Me_(12)Q[6]为"胶囊体"、1,4-二噁烷为"胶囊"芯材、水分子为"胶囊盖"的"分子胶囊"结构,"分子胶囊"通过氢键自组装形成一维超分子链,而一维的超分子链通过Me_(12)Q[6]端口的羰基氧原子与水分子之间的氢键作用横竖交错组成二维具有空洞结构的分子网.     

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.     

三种六元瓜环与Sr(Ⅱ)离子的配位及超分子自组装

本文以六元瓜环及两种部分甲基取代六元瓜环(统称为Q[6]s)为构筑元件,合成了4个Q[6]s-Sr髤离子的配合物,用X射线单晶衍射方法测定了配合物的晶体结构。结果表明,Q[6]s-Sr髤离子配合物自组装形成不同结构的分子链,体系中存在Cl-离子时,Q[6]s-Sr髤离子形成配位聚合链,而只有NO3-离子存在时,形成水分子配位桥连的超分子链。     

六元和七元瓜环与两类端邻苯二甲酰亚胺基紫精轮烷的组装及性质

设计合成了2种不同碳链长度的客体分子1,1'-二甲基邻苯二甲酰亚胺基-4,4'-联吡啶溴化物 (G1)和1,1'-二丁基邻苯二甲酰亚胺基-4,4'-联吡啶溴化物(G2). 利用紫外-可见吸收光谱、 核磁共振波谱和等温滴定量热等方法研究了客体分子G1和G2与六元(Q[6])和七元瓜环(Q[7])的超分子自组装方式. 结果表明, 在加热回流情况下G1与Q[6]利用滑移法能与紫精基团包结形成[2]轮烷结构, 而Q[7]在常温下就能滑过封端基团邻苯二甲酰亚胺与紫精基团包结形成[2]准轮烷结构.     

三种六元瓜环与Sr(Ⅱ)离子的配位及超分子自组装

本文以六元瓜环及两种部分甲基取代六元瓜环(统称为Q[6]s)为构筑元件,合成了4个Q[6]s-Sr(Ⅱ)离子的配合物,用X射线单晶衍射方法测定了配合物的晶体结构。结果表明,Q[6]s-Sr(Ⅱ)离子配合物自组装形成不同结构的分子链,体系中存在Cl-离子时,Q[6]s-Sr(Ⅱ)离子形成配位聚合链,而只有NO3-离子存在时,形成水分子配位桥连的超分子链。     

三种瓜环与4,4′-联吡啶及N,N′-二甲基4,4′-联吡啶盐酸盐相互作用的研究

以七元瓜环(Q[7])和新型椭圆型改性瓜环———对称四甲基取代六元瓜环(TM eQ[6])为主体,4,4′-联吡啶的盐酸盐(44)以及N,N′-二甲基4,4′-联吡啶的盐酸盐(dm44)为客体的主客体相互作用进行了考察.实验结果表明,Q[7]与客体44及dm44作用体系中,客体为了更有效地被主体Q[7]包结,在Q[7]内腔中呈倾斜状分布的几率最高.用核磁共振、循环伏安以及紫外吸收光谱对实验结果进行了印证和补充,验证了TM eQ[6]与客体44及dm44可发生较强的相互作用,形成一维的自组装超分子结构.核磁共振以及循环伏安方法的实验结果表明,没有观察到Q[6]与客体44及dm44的明显作用,而紫外吸收光谱方法证实,Q[6]与客体44确实存在一定的相互作用,比较主客体的结构特征,该作用体系也可能存在自组装的一维超分子结构等多种作用形式.     

Cucurbit[5]uril, Decamethylcucurbit[5]uril and Cucurbit[6]uril. Synthesis, Solubility and Amine Complex Formation

A simple way to prepare cucurbit[5]uril is described. The macrocycles of the cucurbituril type are nearly insoluble in water. The solubilities of cucurbit[5]uril, decamethylcucurbit[5]uril and cucurbit[6]uril in hydrochloric acid, formic acid and acetic acid of different concentrations have been investigated. Due to the formation of complexes between cucurbit[n]urils and protons the solubility increases in aqueous acids. The macrocyclic ligands are able to form complexes with several organic compounds. Thus, the complex formation of the cucurbituril macrocycles with different amines has beenstudied by means of calorimetric titrations. The reaction enthalpy gives noevidence of the formation of inclusion or exclusion complexes. ¹H-NMR measurements show that in the case of cucurbit[5]uril and cucurbit[6]uril the organic guest compound is included within the hydrophobic cavity. Decamethylcucurbit[5]uril forms only exclusion complexes with organicamines. This was confirmed by the crystal structure of the decamethylcucurbit[5]uril-1,6-diaminohexane complex.     

含有葫芦[6]脲的新型准轮烷的合成

通过葫芦[6]脲(CB[6])与两个质子化的1,4-丁二胺在水溶液中于室温下进行超分子自组装, 得到一种新型的准轮烷. 通过¹H NMR, 质谱和¹H ROESY NMR对其结构进行了表征, 证实CB[6]位于质子化1,4-丁二胺的脂肪链上, 通过非共价键与1,4-丁二胺结合, 并且主体(CB[6])与客体的结合的物质的量之比为2∶1.     

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.     

Opposing substitution in cucurbit[6]urils forms ellipsoid cavities: the symmetrical dicyclohexanocucurbit[6]uril is no exception highlighted by inclusion and exclusion complexes

The symmetrical dicyclohexanocucurbit[6]uril has been synthesised by the controlled condensation of the diether of cyclohexanoglycoluril (1) and the dimer of glycoluril (2). The symmetrical dicyclohexanocucurbit[6]uril, (CyH)₂Q[6], characterised by the ¹H NMR spectroscopy, ESMS and further confirmed by single crystal X-ray diffraction of a cobalt aqua exclusion complex, which demonstrates an ellipsoid cavity. Within a cucurbit[6]uril ellipsoid cavity, an inclusion complex of 5,5′-dimethyl-2,2′-bipyridine adopts a preferred orientation, aligning with the longest axis. The ellipsoid cavity is further supported by semiempirical AM1 gas phase calculations.

Preferential orientation of a guest within the ellipsoid cavity of the symmetrical dicyclohexanocucurbit[6]uril     

Study on the Interaction and Properties of Cucurbit[8]uril with Oroxin B

The interaction between cucurbit[8]uril(Q[8]) and oroxin B(ORB) was investigated by UV-visible(UV-Vis) spectroscopy, isothermal titration calorimetry(ITC), mass spectrum(MS) and nuclear magnetic resonance(NMR) spectroscopy. The results showed that ORB formed a 2:1 inclusion complex with Q[8] with a binding constant of 8.266×10⁵ L²·mol^-2. ORB had good scavenging ability for 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS) free radicals(IC₅₀=5.74 μmol/L) and the addition of Q[8] did not significantly affect the antioxidant activity of ORB(IC₅₀=5.76 μmol/L). A phase solubility experiment revealed a 1.86-fold increase in the solubility of ORB when c(Q[8])=100 μmol/L. In vitro drug release experiments showed that the release rate for ORB@Q[8] complex was lower than that of ORB in artificial intestinal juice, and higher than that of ORB in artificial gastric juice.     

Investigation of Host–Guest Compounds of Cucurbit[n=5–8]uril with Some Ortho Aminopyridines and Bispyridine

Host–guest complexes of cucurbit[n=5–8]uril and some examples of ortho substituted pyridines or aminopyridines were examined by ¹H NMR spectroscopy. Portal binding of two ortho aminopyridine free bases, by cucurbit[5]uril, was observed in ¹H NMR spectra. Combined cavity and portal binding in cucurbit[6]uril were observed for both the free base 2-aminomethylpyridine, ampy, the HCl salt, ampy·1HCl, and the salt of 2,2′-bispyridine, bpy·1HCl. Two novel complexes were formed with cucurbit[6]uril. The free base ampyas a dual occupant, formed a 2:1 complex, and bpy·1HCl formed a stable asymmetric 1:1 complex. Only portal binding of 2,6-bisaminomethylpyridine and its salts was observed for cucurbit[6]uril. Fast exchange of the free base and pyridineammonium salts was observed for cucurbit[7-8]uril.This revised version was published online in July 2005 with a corrected issue number.     

Complexation behavior of cucurbit[6]uril with short polypeptides

The binding properties of cucurbit[6]uril towards various peptides have been investigated in acidic aqueous solution. Stability constants and thermodynamic values of the complex formation between following peptides: glycyl-l-alanine, l-leucyl-l-valine, glycyl-l-asparagine, l-leucyl-l-phenylalanine, l-leucyl-l-tryptophan, glycyl-l-histidine, l-glutathione reduced (γ-l-glutamyl-l-cysteinyl-glycine, GSH), and dl-leucyl-glycyl-dl-phenylalanine) with cucurbit[6]uril in aqueous formic acid (50%, v/v) have been calculated from calorimetric titrations. From these results it can be seen that the peptides form exclusion complexes with cucurbit[6]uril. Due to the polar peptide bond they are not included within the hydrophobic cavity of cucurbit[6]uril. The complex formation is favoured by entropic contributions. The release of water molecules from the polar amino groups of the peptides and the carbonyl groups of cucurbituril are responsible.