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机构地区:[1]中国科学院兰州化学物理研究所,甘肃兰州730000 [2]云南大学化学科学与工程学院,云南昆明650091 [3]云南省第一人民医院,云南昆明650032 [4]曲阜师范大学化学科学学院,山东曲阜273165
出 处:《化学研究》2012年第4期85-90,共6页Chemical Research
摘 要:用半经验量子化学AM1方法对天然苝醌化合物痂囊腔菌素A(EA)的分子构型和分子内氢键进行了研究;从EA可能的64种构型中选择16种进行了计算.结果表明,EA的X射线晶体结构对应的构型是II型左旋(A)a,a型(II-L-A-a,a);小的生成热差值可以使得异构体间的转换容易进行,有利于发生分子内质子传递.尽管采用AM1方法计算得到的EA各种构象的平面性有所差别,但都很接近晶体的平面性.此外,EA分子内氢键键能的平均值为22.9kJ/mol;II型的氢键键能比I型的大,(9,10)位的氢键键能比(3,4)位的大;EA的平面性是由苝醌环上的侧链取代所决定,而与分子内是否存在氢键无关.The molecular configuration and intra-molecular hydrogen bond of natural perylenequinone elsinochrome A(EA) were examined with semi-empirical quantum chemical method AM1.Sixteen configurations were selected from 64 possible configurations and calculated.Results indicate that the X-ray crystal structure of EA corresponds to type-II left-hand rotation a,a configuration(II-L-A-a,a).A small difference in formation heat allows easy inter-transformation among various isomers,which facilitates intra-molecular proton transfer.Besides,though the planarities of EA configurations calculated with AM1 method are somewhat different,they are all similar to those of X-ray crystals.Moreover,the average intra-molecular hydrogen bond energy of EA is 22.9 kJ/mol.The hydrogen bond energies of type-II configuration are larger than that of type-I configuration,while hydrogen bond energies at(9,10) positions are greater than that at(3,4) positions.Furthermore,the planarity of EA is determined by side-chain substitution on perylenequinone ring and is not dependent on whether or not intra-molecular hydrogen bond exists.
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