Reported in this paper is a new finding based on a spectroscopic and electrochemical study of a supramolecular polymer in dilute solution. Dissolved in a mixture of dichloromethane and acetonitrile, zinc-tetraphenylporphyrin (ZnTPP) can complex with a polymethacrylate bearing an azopyridine moiety (AzPy) through the axial coordination between the metal and pyridyl group. The self-assembled polymer (PAzPy-ZnTPP) displays different photoluminescence and redox behaviors compared with those of noncomplexed ZnTPP. Moreover, the reversible trans-cis-photoisomerization of azopyridine upon UV and visible light irradiation was found to alter the equilibrium of the axial coordination between azopyridine and ZnTPP in solution, resulting in photoregulable redox potentials and fluorescence emission of the metalloporphyrin. The results suggest that supramolecular polymer solutions could enhance the mechanism of photoinduced change in the degree of complexation, which gives rise to a phenomenon of photoregulation of the electrochemical and optical properties. (c) 2006 Wiley Periodicals, Inc.