水溶性卟啉与β-环糊精相互作用的分子动力学模拟

Molecular dynamics simulation on the interaction of watersoluble porphyrins with β-cyclodextrins

卟啉和环糊精通过包结作用形成的超分子体系以其独特的物理和化学性质在多个领域得到了广泛的应用。为了考察环糊精与卟啉的包结作用,本文采用分子动力学模拟方法研究了不同结构的水溶性卟啉和β-环糊精所形成的稳定包结化合物,并考察了包结物形成的机理。计算结果表明,在水溶液中,卟啉所带电荷的种类和位置以及环糊精的结构均会影响卟啉与环糊精的包结作用。吡啶基阳离子型卟啉难以与环糊精形成稳定包结化合物。而阴离子型卟啉、非离子型卟啉和正电荷远离卟啉环的铵基阳离子型卟啉均能与环糊精形成1：1的稳定包结物,且范德华相互作用是其稳定包结的主要驱动力。相对于β-环糊精和羟丙基-β-环糊精,2, 3, 6-三甲基-β-环糊精与卟啉分子之间的范德华相互作用更强,形成的包结物更稳定。

The supramolecular system formed by the inclusion of cyclodextrin with porphyrin has been widely used in many fields because of its unique physical and chemical properties. To investigate the inclusion of β-cyclodextrin with water-solubel porphyrin, the inclusion complexes formed by different porphyrins with cyclodextrin and the corresponding mechanism were studied using molecular dynamics simulation. The calculated results show that, in aqueous solution, the type and position of the charge in porphyrin and the structure of cyclodextrin affect the inclusion of porphyrin with cyclodextrin. The cationic porphyrin with pyridyl group hardly forms the stable inclusion complex with cyclodextrin in aqueous solution, whereas the anionic porphyrin, non-ionic porphyrin and cationic porphyrin with ammonium group can form the stable 1：1 inclusion complexes with cyclodextrins. The main driving force of inclusion complex is the Van der Waals interaction. The interaction of heptakis（2,3,6-tri-O-methyl）-β-CD with porphyrins are stronger and the corresponding complexes are more stable than that of β-cyclodextrin and hydroxypropyl-β-cyclodextrin.