Charge Transfer of Tetraphenylporphyrin Zinc Complexes Incorporated in a Poly(2-vinylpyridine) Matrix

Abstract

<jats:p> An indium tin oxide (ITO) electrode was coated by a poly(2-vinylpyridine) (P-2VP) film incorporating tetraphenylporphyrin zinc ( ZnTPP ) as a redox center. A cyclic voltammogram (CV) exhibited a couple of redox waves at 0.7 V (vs Ag / AgCl ). The potential-step chronoamperospectrometry (PSCAS) measurement was carried out on the modified electrode immersed in a 0.1 M LiClO <jats:sub>4</jats:sub> aqueous solution at pH 3.5 under argon atmosphere. Assuming a random distribution of the redox species in the macromolecular structure, the charge transfer distance between the adjacent ZnTPP complexes was obtained as 1.08 nm. The charge hopping distance between the redox centers (1.01 nm) and the bounded motion distance (0.07 nm after 2h) were obtained according to their different response time in the electrochemical measurement. Considering the contributions from both the charge hopping and bounded motion, the second order rate constant of electron hopping was 4.1 × 10<jats:sup>4</jats:sup> M<jats:sup>−1</jats:sup>s<jats:sup>−1</jats:sup>. </jats:p>