Spectral and photochemical properties of covalently linked dyads based on 2-styrylquinoline and 6-hydroxy-2-naphthoic acid

Abstract

Photophysical and photochemical properties of bichromophoric covalently linked SnN dyads (n = 3, 5, 9), in which the 2-styrylquinoline (SQ) and 6-hydroxy-2-naphthoic acid (Np) moieties are linked by the dioxypolymethylene bridge–O–(CH₂)_n–O–have been studied. The properties of the dyads have been compared with those of the model compounds 2-(4-methoxystyryl)quinoline and methyl 6-hydroxy-2-naphthoate. Inductive-resonance (Förster) energy transfer (FRET) from the Np to the SQ unit with an efficiency up to 99.6% is observed in the S₁ state of the dyads. The Np unit in the neutral form does not affect the photoisomerization of the SQ unit regardless of the form of the latter, neutral or protonated (cationic). The Np moiety in the anionic (deprotonated) form hinders the photoisomerization of the SQ moiety, presumably, as a result to a combined action of several factors.