Electrochemical and in situ spectroelectrochemical behavior of 2,3,7,8,12,13,17,18-octakis(hexyl-thio) tetraazaporphyrin (H(2)OHTTAP) and (Zn(II)OHTTAP)

The characterization of free base porphyrin 2,3,7,8,12,13,17,18-octakis(hex yl-thio) tetraazaporphyrin (H(2)OHTTAP) and its zinc(II) complexes [Zn(II)O HTTAP] containing eight thioether groups at the beta -pyrrole positions of the macrocycle was reported. Results obtained by cyclic voltammetry and dif ferential pulse voltammetry indicated a five-electron reduction in five ste ps for each complex. They were oxidized in two single-electron-transfer ste ps to yield pi -cation radicals and dications and reduced in three single-e lectron-transfer steps to yield pi -anion radicals, dianions and trianions, respectively. The redox property of H(2)OHTTAP was unusual as compared to porphyrins (PPs) and phthalocyanines (Pcs). Each process was monitored by i n situ thin-layer spectroelectrochemistry, which indicated that only the Li gand was electroactive. The existence of the eight hexylthio groups was res ponsible for the intrastack interactions and enhanced intracolumnar and int ercolumnar electron motions, resulting in improved conductivity. Copyright (C) 2001 John Wiley & Sons, Ltd.