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

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)2+4(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。

Investigation of the Configuration Characteristics and Water- Exchange Reactions of Aluminium(III)-Maltolate Complexes by Density Functional Theory

The following studies were carried out at B3LYP/6-311+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 water-exchange rate constants log k_ex (s^-1) of three sites were 2.4 (Al(ma)(H₂O)²⁺₄(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.