Strongly modified [2,2′-bipyridyl]-3,3′-diol (BP(OH)2):: a system undergoing excited state intramolecular proton transfer as a photostabilizer of polymers and as a solar energy collector

Six new compounds, derivatives of [2,2'-bipyridyl]-3.3'-diol (BP(OH)(2)) are recommended as useful modifications of the parent structure. One group, three molecules with conjugate aromatic substituents (6-methyl-6'-styryl-BP(OH)(2), 6-(4-methoxystyryl)-6'-methyl-B P(OH)(2), 6-methyl-6'-(4-phenylstyryl)-BP(OH)(2)), are potential solar energy concentrators - they have absorption spectra red shifted with respect to BP(OH)2. To the second group belong the derivatives with the aliphatic side chains, better "accepted" by polyethylene than the parent molecule. These compounds are designed to improve their function as photostabilizers of polymers. All six new compounds were synthesized and their photophysical characteristics were studied. Absorption spectra, phototautomeric fluorescences and their excitation spectra. as well as quantum yields and lifetimes are reported. (C) 2001 Elsevier Science B.V. All rights reserved.