Ground- and excited-state properties of some naphthof lavyliums

A series of five, structurally related, substituted 2-phenyl-benzopyrylium (flavylium) salts were synthesized and characterized by NMR, absorption, and fluorescence techniques. Their hydration and deprotonation constants were obtained through thermodynamic and relaxation kinetic methods. Metallic complexation with the two compounds possessing a catechol group and its effect on the fluorescence intensity was also studied. The ground state properties of the five pigments are correlated with the theoretical data collected through AM1 molecular orbital calculations.