密度泛函理论方法研究铝-麦芽酚配合物的形态结构与水交换反应

摘要

在B3LYP/6-311 +G(d,p)基组水平下采用密度泛函理论方法系统开展了以下工作:(1)优化得到1∶1、1∶2和1∶3铝-麦芽酚配合物10种可能构型的静态结构、NPA电荷以及能量参数,计算得到Al(ma)3配合物4种异构体的核磁共振、紫外和红外等光谱学数据并与文献实验值比较,证明本文采用的计算方法和模型适用于铝-麦芽酚体系的研究;(2)模拟1∶1和1∶2铝-麦芽酚配合物9种可能位点的水交换反应,其中3个位点计算得到的水交换反应速率对数log kex(s-1)分别为2.4 (Al(ma)(H2O)24+(cis to ma))、2.6(cis-Al(ma)2(H2O)2+(I))和3.0 (trans-Al(ma)2(H2O)2+(I)),与实验值2.5 (Al(ma)2+)和3.3(Al(ma)2+)相符,说明相应位点为反应活性位点;(3)探讨铝-麦芽酚配合物毒性与其形态结构之间的相关机制.%The following studies were carried out at B3LYP/6-31 l+G(d,p) level by density functional theory:(1)Ten possible configurations of 1∶1/1∶2/1∶3 Al-maltolate complexes were optimized and their static structural properties,NPA charges and energies were obtained.The 27Al NMR/1H NMR chemical shifts,ultraviolet spectral data and infrared absorptions of four isomers of Al(ma)3 were calculated and found to be corresponding with experimental results reported by literatures,which proved the applicability of the density functional theory.(2) Nine possible pathways of water-exchange reactions of 1∶1/1∶2 Al-maltolate complexes were simulated.The logarithm values of waterexchange rate constants log kex(S-1) of three sites were 2.4 (Al(ma)(H2O)24+(cis to ma)),2.6 (cis-Al(ma)2(H2O)2+(I))and 3.0 (trans-Al(ma)2(H2O)2+(I)) respectively,which were in good agreement with the experimental values of 2.5 (Al(ma)2+) and 3.3 (Al(ma)2+),and the corresponding sites were regarded as the active sites.(3) The mechanism of the relationship between toxicity of Al-maltolate complexes and their different speciation was discussed.