The binding interactions between 4-aminopyridine(4-AP) and a series of cucurbit[n]urils(Q[5], Q[6],TMe Q[6], Q[7], Q[8]) have been studied using1H NMR spectroscopy, UV–vis absorption spectroscopy,isothermal titration...The binding interactions between 4-aminopyridine(4-AP) and a series of cucurbit[n]urils(Q[5], Q[6],TMe Q[6], Q[7], Q[8]) have been studied using1H 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], TMe Q[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.展开更多
The slightly water-soluble anticancer drug camptothecin(CPT) and its inclusion complexes with cucurbit[n = 7,8]uril(Q[n](n = 7,8)) were investigated.The formation of 1:2 complexes with Q[n](n = 7,8) in aqueous solutio...The slightly water-soluble anticancer drug camptothecin(CPT) and its inclusion complexes with cucurbit[n = 7,8]uril(Q[n](n = 7,8)) were investigated.The formation of 1:2 complexes with Q[n](n = 7,8) in aqueous solution was confirmed by fluorescence spectroscopy and the apparent stability constants were determined to be higher than 3.01 × 1012 L2/mol2.The solid inclusion complexes of CPT and Q[n](n = 7,8) were also prepared by the co-evaporation method and characterized by Fourier transformation-infrared spectroscopy,differential scanning calorimetry and powder X-ray diffraction.Aqueous solubility and dissolution studies indicate that the complexes exhibited significantly increased dissolution rates compared with the pure drug and physical mixtures.The potential of Q[7] or Q[8] for stabilizing lactone modality of CPT was investigated by the High Performance Liquid Chromatography(HPLC) method.The results reveal more than 63% CPT lactone form(active form) in CPT-Q[7] or Q[8] complexes compared to only 36% CPT lactone form in the absence of Q[7] or Q[8] after being incubated in the phosphate buffer solution(pH 7.4 at 37 °C) for 5h.展开更多
It is challenging to recognize neutral hydrophilic molecules in water.Effective use of hydrogen bonds in water is generally accepted to be the key to success.In contrast,hydrophobic cavity is usually considered to pla...It is challenging to recognize neutral hydrophilic molecules in water.Effective use of hydrogen bonds in water is generally accepted to be the key to success.In contrast,hydrophobic cavity is usually considered to play an insignificant role or only to provide a nonpolar microenvironment for hydrogen bonds.Herein,we report that hydrophobic cavity alone can also strongly bind neutral,highly hydrophilic molecules in water.We found that cucurbit[n]urils(n=7,8)bind 1,4-dioxane,crown ethers and monosaccharides in water with remarkable affinities.The best binding constant reaches 10^(7) M^(−1) for cucurbit[8]uril,which is higher than its binding affinities to common organic cations.Density functional theory(DFT)calculations and control experiments reveal that the hydrophobic effect is the major contributor to the binding through releasing the cavity water and/or properly occupying the weakly hydrated cavity.However,hydrophobic cavity still prefers nonpolar guests over polar guests with similar size and shape.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.21871064)the National College Students’Innovative Training Program of China(No.2020053)+1 种基金the“Undergraduate Teaching Project”of Guizhou University(No.201936)the Student Research Training Foundation of Guizhou University,China(No.(2019)106).
基金supported by the Innovation Program for Highlevel Talents of Guizhou Province (No. 2016-5657)the University of Hull for support。
文摘The binding interactions between 4-aminopyridine(4-AP) and a series of cucurbit[n]urils(Q[5], Q[6],TMe Q[6], Q[7], Q[8]) have been studied using1H 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], TMe Q[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.
基金supported by the Talented Person Project of Guizhou University (2007016)Science and Technology Fund of Guizhou Province (20082294)Governor Foundations of Guizhou Province (200812)
文摘The slightly water-soluble anticancer drug camptothecin(CPT) and its inclusion complexes with cucurbit[n = 7,8]uril(Q[n](n = 7,8)) were investigated.The formation of 1:2 complexes with Q[n](n = 7,8) in aqueous solution was confirmed by fluorescence spectroscopy and the apparent stability constants were determined to be higher than 3.01 × 1012 L2/mol2.The solid inclusion complexes of CPT and Q[n](n = 7,8) were also prepared by the co-evaporation method and characterized by Fourier transformation-infrared spectroscopy,differential scanning calorimetry and powder X-ray diffraction.Aqueous solubility and dissolution studies indicate that the complexes exhibited significantly increased dissolution rates compared with the pure drug and physical mixtures.The potential of Q[7] or Q[8] for stabilizing lactone modality of CPT was investigated by the High Performance Liquid Chromatography(HPLC) method.The results reveal more than 63% CPT lactone form(active form) in CPT-Q[7] or Q[8] complexes compared to only 36% CPT lactone form in the absence of Q[7] or Q[8] after being incubated in the phosphate buffer solution(pH 7.4 at 37 °C) for 5h.
基金supported by the National Natural Science Foundation of China(22101125)Shenzhen Science and Technology Innovation Committee(JCYJ20180504165810828)+2 种基金Shenzhen“Pengcheng Scholar”Guangdong High-Level Personnel of Special Support Program(2019TX05C157)Guangdong Provincial Key Laboratory of Catalysis(2020B121201002)。
文摘It is challenging to recognize neutral hydrophilic molecules in water.Effective use of hydrogen bonds in water is generally accepted to be the key to success.In contrast,hydrophobic cavity is usually considered to play an insignificant role or only to provide a nonpolar microenvironment for hydrogen bonds.Herein,we report that hydrophobic cavity alone can also strongly bind neutral,highly hydrophilic molecules in water.We found that cucurbit[n]urils(n=7,8)bind 1,4-dioxane,crown ethers and monosaccharides in water with remarkable affinities.The best binding constant reaches 10^(7) M^(−1) for cucurbit[8]uril,which is higher than its binding affinities to common organic cations.Density functional theory(DFT)calculations and control experiments reveal that the hydrophobic effect is the major contributor to the binding through releasing the cavity water and/or properly occupying the weakly hydrated cavity.However,hydrophobic cavity still prefers nonpolar guests over polar guests with similar size and shape.
