Spectral and photochemical properties of styrylquinoline-merocyanine dyads based on 2-styrylquinoline

Abstract

The properties of styrylquinoline-merocyanine dyads, in which the styrylquinoline (SQ) and merocyanine (MC) moieties are linked with a bridge of three (SQ3MC dyad) and eleven (SQ11MC dyad) methylene groups, have been compared with the properties of the model compounds 2-(4-methoxystyryl)quinoline and 1-ethyl-2-(4-methoxystyryl)quinolinium perchlorate, of which the latter is the O-methylated merocyanine derivative. Efficient inductive-resonance energy transfer (FRET) from the SQ to the MC moiety has been revealed, resulting in the quenching of the former and sensitization of the latter. The quenching of the SQ moiety manifests itself in a decrease in the quantum yield of trans-cis photoisomerization and fluorescence, and the sensitization of the MC moiety enhances these parameters. The efficiency of energy transfer decreases from 96 to 87% on passing from the SQ3MC to SQ11MC dyad.