Tran Thai T H, Chen Guan-Ling, Hoang Tuan K A, Kuo Ming-Yu, Su Yuhlong O
Department of Applied Chemistry, National Chi Nan University , 1 University Road, Puli, Nantou 545, Taiwan.
Department of Chemical Engineering, University of Waterloo , 200 University Avenue, Waterloo ON N2L 3G1, Canada.
J Phys Chem A. 2017 Sep 21;121(37):6925-6931. doi: 10.1021/acs.jpca.7b05002. Epub 2017 Sep 8.
In this study, the electrochemical behavior of zinc meso-substituted porphyrins in the presence of imidazole is examined by using both cyclic voltammetry (CV) and density functional theory (DFT) methods. The results show that the first half-wave oxidation potentials (1st E) of zinc porphyrins complexed with imidazole all move to the negative side, while the second ones (2nd E) move to the positive side, resulting in larger half-wave oxidation potential splittings of the two oxidation states (ΔE = second E - first E) comparing with the zinc porphyrins. By employing DFT calculations, we have found that both sterically controlled inter π-conjugation between porphyrin rings and meso-substituted phenyl groups and deformation of porphyrin rings do play important roles in contributing to the half-wave oxidation potentials. Imidazole exhibits strong effects on the deformation of porphyrin rings which is dominant in determining the first E while the inter π-conjugation between porphyrin rings and meso-substituted phenyl groups mainly contributes to the second E. Without imidazole, the inter π-conjugation between porphyrin rings and meso-substituted phenyl groups is the only important criterion which effects both first E and second E of zinc porphyrins.
在本研究中，运用循环伏安法（CV）和密度泛函理论（DFT）方法，研究了中取代锌卟啉在咪唑存在下的电化学行为。结果表明，与咪唑络合的锌卟啉的第一个半波氧化电位（第一E）均向负方向移动，而第二个半波氧化电位（第二E）向正方向移动，与锌卟啉相比，导致两种氧化态的半波氧化电位分裂更大（ΔE = 第二E - 第一E）。通过DFT计算，我们发现卟啉环与中取代苯基之间的空间控制的π-共轭以及卟啉环的变形在贡献半波氧化电位方面确实起着重要作用。咪唑对卟啉环的变形表现出强烈影响，这在决定第一E时起主导作用，而卟啉环与中取代苯基之间的π-共轭主要影响第二E。没有咪唑时，卟啉环与中取代苯基之间的π-共轭是影响锌卟啉第一E和第二E的唯一重要标准。
