Fluorescence quenching of a few aromatic amines by inorganic anions

Abstract

Inorganic anions-induced fluorescence quenching of seven aromatic amines has been studied up to 0.1<i>M </i> concentration. The fluorescence intensities of all the aromatic amines (except aniline) remain unaffected when CI^- and SCN^-are used as quenchers, whereas sufficient decrease in the fluorescence intensities is noticed when Br^- and I^- are used as quenchers. Based on the results obtained in the case of aniline, the fluorescence quenching efficiency of the anions can be ordered as: SCN^- < Br^- < I^-. Observed results cannot be explained completely either by spin-orbit coupling interaction or by charge transfer mechanism, although the latter seems to be more appropriate as log <i>k</i>q cannot be correlated with the spin-orbit coupling constants of the quencher atom when aniline is considered.