L-苏氨酸卟啉锌配合物结构及ECD谱理论研究  

Theoretical analysis of ECD spectrum of L-Thr-TPPZn^(Ⅱ)

作　　者：周辉[1,2] 蒋启华[1,3] 蒋君好[1] 邓萍[1,2] 

机构地区：[1]重庆医科大学药学院,重庆400016 [2]重庆市生物化学与分子药理学重点实验室,重庆400016 [3]重庆高校药物工程研究中心,重庆400016

出　　处：《原子与分子物理学报》2016年第1期41-45,共5页Journal of Atomic and Molecular Physics

摘　　要：采用密度泛函理论(DFT)方法和极化连续介质模型(PCM),在B3LYP和混合基组(C,H原子采用6-31G(d);Zn、N、O采用6-311++G(2d,p))水平对L-苏氨酸卟啉锌(L-Thr-TPPZnII)的基态几何构型进行了优化;以优化得到的稳定构型为基础,采用含时密度泛函理论(TD-DFT)方法,在相同基组水平进行了电子圆二色谱(ECD)研究,根据计算获得的电子跃迁吸收波长(λ)和电子旋转强度(R)拟合得到了ECD谱.除吸收峰位置有一定的蓝移外,计算获得的ECD谱带形与实验谱基本吻合.通过跃迁性质分析对实验光谱进行了理论解析.理论研究发现L-Thr-TPP ZnII的ECD谱吸收带主要来源于分子内的π→π*的荷移跃迁.353 nm处的负性Cotton效应具有明显的分子内电子转移特征,电子从卟啉环向氨基酸残基转移.The geometry of L - Thr - TPPZnII was optimized using density functional theory （DFr） at the B3LYP level of theory with the mixed basis sets： 6 -31G（d） for C and H, and 6 -311 ＋ ＋ G（2d, p） for Zn, Fe, N and O atoms. Based on the optimized results, the electron transition absorption wavelengths （A） and rotational strengths （R）, and electronic circular dichroism （ECD） spectrum were calculated using time -dependent densi- ty functional theory （TD -DFT） with the same functional and basis sets. In these calculations, solvent effects of CHCl3 were included using the polarized continuum model （PCM）. Comparing with the experimental date, the calculated absorption peaks exhibit blue shifts and calculated ECD spectrum is in good agreement with experi- mental one. Detailed analyses of the dominant transitions reveal that all the cotton effects in the ECD spectrum are caused by the π→→ charge transfer transition. The circular dichroism band in 353 nm is dominated by the intermolecular charge transfer transition form porphyrin ring to amino acid residue.

关 键 词：L-苏氨酸 锌卟啉 圆二色谱 手性光学性质 理论解析 

分 类 号：O641[理学—物理化学] R914.5[理学—化学]