| Abstract: | The correlation between intrinsic photostability (??1R) and structure of several intramolecularly hydrogen-bonded heterocycles containing suitable o-hydroxyphenyl groups is briefly discussed in terms of the changes in resonance energy resulting in such compounds from a reversible keto-enol rearrangement in the lowest excited singlet state. The influence of intramolecular hydrogen bonding, resonance and steric effects on photostability in o-hydroxyphenylquinazolines as elucidated with the aid of spectroscopic methods is discussed in detail. |
