Fluorescence Quenching and Enhancement by H-bonding Interactions in Some Nitrogen Containing Fluorophores

Abstract

The benzo[de]benzo[4,5]imidazo[2,1-a]isoquinolin-7-one (1) shows solvent dependent fluorescence emission. The compound shows quenching of fluorescence emission on interaction with polyhydroxy compounds such as 1,3-dihydroxybenzene, 1,4-dihydroxybenzene. The result on fluorescence quenching is attributed to the hydrogen bonding interactions. Similar observation of fluorescence quenching by protic solvent is observed with isoindolo[2,1-a] perimidin-12-one (2). In the case of 2-(2-amino-phenyl)-isoindole-1,3-dione (3) enhancement of fluorescence emission in methanol solution is observed over benzene solution. This is explained on the basis of intermolecular hydrogen bonding. The crystal structure of adduct of 1 with 1,3-dihydroxybenzene, 1,4-dihydroxybenzene respectively and 3 are reported.