Molecular dynamics (MD) simulations are performed to study the stability of structure H clathrate-hydrates of methane+large-molecule guest substance (LMGS) at temperatures of 270, 273, 278 and 280 K under canonic...Molecular dynamics (MD) simulations are performed to study the stability of structure H clathrate-hydrates of methane+large-molecule guest substance (LMGS) at temperatures of 270, 273, 278 and 280 K under canonical (NVT-) ensemble condition in a 3×3×3 structure H unit cell replica with 918 TIP4P water molecules. The studied LMGS are 2-methylbutane (2-MB), 2,3-dimethylbutane (2,3-DMB), neohexane (NH), methylcyclohexane (MCH), adamantane and tert-butyl methyl ether (TBME). In the process of MD simulation, achieving equilibrium of the studied system is recognized by stability in calculated pressure for NVT-ensemble. So, for the accuracy of MD simulations, the obtained pressures are compared with the experimental phase diagrams. Therefore, the obtained equilibrium pressures by MD simulations are presented for studying the structure H clathrate-hydrates. The results show that the calculated temperature and pressure conditions by MD simulations are consistent with the experimental phase diagrams. Also, the radial distribution functions (RDFs) of host-host, host-guest and guest-guest molecules are used to analysis the characteristic configurations of the structure H clathrate-hydrate.展开更多
Ursolic acid(UA) and oleanolic acid(OA) are insoluble drugs. The objective of this study was to encapsulate them into β-cyclodextrin(β-CD) and compare the solubility and intermolecular force of β-CD with the two is...Ursolic acid(UA) and oleanolic acid(OA) are insoluble drugs. The objective of this study was to encapsulate them into β-cyclodextrin(β-CD) and compare the solubility and intermolecular force of β-CD with the two isomeric triterpenic acids. The host-guest interaction was explored in liquid and solid state by ultraviolet-visible absorption,1H NMR, phase solubility analysis, and differential scanning calorimetry, X-ray powder diffractometry, and molecular modeling studies. Both experimental and theoretical studies revealed that β-CD formed 1: 1 water soluble inclusion complexes and the complexation process was naturally favorable. In addition, the overall results suggested that ring E with a carboxyl group of the drug was encapsulated into the hydrophobic CD nanocavity. Therefore, a clear different inclusion behavior was observed, and UA exhibited better affinity to β-CD compared with OA in various media due to little steric interference, which was beneficial to form stable inclusion complex with β-CD and increase its water solubility effectively.展开更多
The aryl moiety which was bonded as a functional group on the primary alcohol side ofβ-CD or the secondary alcohol side of β-CD or the secondary alcohol side of β-CD with anethylenediamino chain could show remarkab...The aryl moiety which was bonded as a functional group on the primary alcohol side ofβ-CD or the secondary alcohol side of β-CD or the secondary alcohol side of β-CD with anethylenediamino chain could show remarkable different molecular recognition abilities in thecomplexation with small molecular guests such as alkanes, cycloketones etc.展开更多
The molecular recotwtion abilities of β-naphthoated β-CD derivatives as the host compounds were studied: 3-o-β-Naphthoyl-β-CD has a largely improved association constant with cyclohexanol than the corresponding 6-...The molecular recotwtion abilities of β-naphthoated β-CD derivatives as the host compounds were studied: 3-o-β-Naphthoyl-β-CD has a largely improved association constant with cyclohexanol than the corresponding 6-position substituted β-CD derivative has. On the other hand, the polarisablity and the sturcture of the gueset molecule are also important factors which affect the association constant. Cyclohexane may form the 1:2 type inclusion compound with the host compound in this report.展开更多
This paper mainly elaborated the recent developments of the studies on the new type zeohite molecular sieve host-nanoguest composite materials composing of molecular sieve chaimels or cages encapsulated nanoscale mate...This paper mainly elaborated the recent developments of the studies on the new type zeohite molecular sieve host-nanoguest composite materials composing of molecular sieve chaimels or cages encapsulated nanoscale materials from the point of nanochemistry and material science,and the trends of development in this field. As the research of the properties of this kind of materials are gomg on. it is possible that this kind of host-guest nanocomposite materials will be usd in some fields. such as science and high technology fields. as the new type of ptical. electrical and magnetic materials in the level of molecular assembly. This paper contains the following contents:hosts and guests; the sizes and shapes of guests; the optical, electrical and magnetic properties of the materials; the syntheses and characterizations of the materials; the applications of the materials and forecast.展开更多
文摘Molecular dynamics (MD) simulations are performed to study the stability of structure H clathrate-hydrates of methane+large-molecule guest substance (LMGS) at temperatures of 270, 273, 278 and 280 K under canonical (NVT-) ensemble condition in a 3×3×3 structure H unit cell replica with 918 TIP4P water molecules. The studied LMGS are 2-methylbutane (2-MB), 2,3-dimethylbutane (2,3-DMB), neohexane (NH), methylcyclohexane (MCH), adamantane and tert-butyl methyl ether (TBME). In the process of MD simulation, achieving equilibrium of the studied system is recognized by stability in calculated pressure for NVT-ensemble. So, for the accuracy of MD simulations, the obtained pressures are compared with the experimental phase diagrams. Therefore, the obtained equilibrium pressures by MD simulations are presented for studying the structure H clathrate-hydrates. The results show that the calculated temperature and pressure conditions by MD simulations are consistent with the experimental phase diagrams. Also, the radial distribution functions (RDFs) of host-host, host-guest and guest-guest molecules are used to analysis the characteristic configurations of the structure H clathrate-hydrate.
基金supported by grants from the National Natural Science Foundation of China (21303086)the Natural Science Foundation of Jiangsu Province (BK20130884)the Research Fund for Doctoral Program of Higher Education (20123234120012)
文摘Ursolic acid(UA) and oleanolic acid(OA) are insoluble drugs. The objective of this study was to encapsulate them into β-cyclodextrin(β-CD) and compare the solubility and intermolecular force of β-CD with the two isomeric triterpenic acids. The host-guest interaction was explored in liquid and solid state by ultraviolet-visible absorption,1H NMR, phase solubility analysis, and differential scanning calorimetry, X-ray powder diffractometry, and molecular modeling studies. Both experimental and theoretical studies revealed that β-CD formed 1: 1 water soluble inclusion complexes and the complexation process was naturally favorable. In addition, the overall results suggested that ring E with a carboxyl group of the drug was encapsulated into the hydrophobic CD nanocavity. Therefore, a clear different inclusion behavior was observed, and UA exhibited better affinity to β-CD compared with OA in various media due to little steric interference, which was beneficial to form stable inclusion complex with β-CD and increase its water solubility effectively.
文摘The aryl moiety which was bonded as a functional group on the primary alcohol side ofβ-CD or the secondary alcohol side of β-CD or the secondary alcohol side of β-CD with anethylenediamino chain could show remarkable different molecular recognition abilities in thecomplexation with small molecular guests such as alkanes, cycloketones etc.
基金国家自然科学基金重点项目“高效耐盐两亲聚合物超分子包合驱油体系增效方法及作用机理”(项目编号52130401)国家自然科学基金青年项目“低渗裂缝油藏再粘接超分子凝胶颗粒研制及其封堵调控机理研究”(项目编号52204064)、“末端主客识别型速溶聚合物设计合成及其超分子体系黏度剪切调控机制”(项目编号52104055)国家自然科学基金外国青年学者项目“Construction method and mechanism of low concentration salt-tolerant amphiphilic”(项目编号52250410349)。
文摘The molecular recotwtion abilities of β-naphthoated β-CD derivatives as the host compounds were studied: 3-o-β-Naphthoyl-β-CD has a largely improved association constant with cyclohexanol than the corresponding 6-position substituted β-CD derivative has. On the other hand, the polarisablity and the sturcture of the gueset molecule are also important factors which affect the association constant. Cyclohexane may form the 1:2 type inclusion compound with the host compound in this report.
文摘This paper mainly elaborated the recent developments of the studies on the new type zeohite molecular sieve host-nanoguest composite materials composing of molecular sieve chaimels or cages encapsulated nanoscale materials from the point of nanochemistry and material science,and the trends of development in this field. As the research of the properties of this kind of materials are gomg on. it is possible that this kind of host-guest nanocomposite materials will be usd in some fields. such as science and high technology fields. as the new type of ptical. electrical and magnetic materials in the level of molecular assembly. This paper contains the following contents:hosts and guests; the sizes and shapes of guests; the optical, electrical and magnetic properties of the materials; the syntheses and characterizations of the materials; the applications of the materials and forecast.