Department of Applied Chemistry, National Chi Nan University, 1 University Road, Puli, Nantou Hsien, Taiwan 545.
J Phys Chem A. 2012 Feb 16;116(6):1632-7. doi: 10.1021/jp209555k. Epub 2012 Feb 2.
Electrochemical properties of substituted free base meso-tetraphenylporphyrins (H(2)T(o,o'-X)PP, H(2)T(o-X)PP, and H(2)T(p-X)PP, where X = OCH(3), CH(3), H, F, or Cl on the phenyl rings) are examined by cyclic voltammetry. When a substituent is located only at the para position of the meso-phenyl group, the difference between the first and second oxidation potentials (ΔE(ox), i.e., E(2)(ox) - E(1)(ox)), is generally significantly smaller than those of the H(2)TPPs with bulky o,o'-substituents on the phenyl group. This trend is elucidated with density functional theory calculations and attributed mainly to the sterically controlled π-conjugation of the meso-phenyl groups to the central porphyrin ring, rather than the often discussed deformation of porphyrin.
取代的游离碱卟啉（H(2)T(o,o'-X)PP、H(2)T(o-X)PP 和 H(2)T(p-X)PP，其中 X = OCH(3)、CH(3)、H、F 或 Cl 在苯基环上）的电化学性质通过循环伏安法进行了研究。当取代基仅位于间位苯基时，第一和第二氧化电势之间的差异（ΔE(ox)，即 E(2)(ox) - E(1)(ox))通常明显小于具有较大 o,o'-取代基的 H(2)TPPs。这种趋势通过密度泛函理论计算得到了解释，并主要归因于间位苯基到中心卟啉环的空间控制的π共轭，而不是通常讨论的卟啉变形。
