5,10,15,20-Tetrakis(4-aminophenyl)porphyrin
(TAPP) undergoes oxidative
polymerization to form electronically conductive, nanofibrous structures
in which the porphyrin units are linked by phenazine bridges. Polymerizations
by chemical oxidation, electrochemical oxidation, and interfacial
oxidative polymerization are described. Poly-TAPP (pTAPP) films have
been characterized using scanning electron microscopy, cyclic voltammetry,
electrochemical impedance spectroscopy, and UV–vis spectroscopy.
The polymer morphology is consistently nanofibrous, with some differences
depending on the specific synthetic method. The polymer films show
distinctive electrochromism at different redox and protonation states.
A Pourbaix diagram correlates the proposed redox and protonation states
of the polymer with applied potential, pH, and perceived color of
the film. pTAPP shows the lowest resistance to oxidative doping/dedoping
at low pH and potentials between +0.4 and +0.5 V vs Ag/AgCl