FLUORESCENCE QUENCHING OF A FEW AROMATIC-AMINES BY INORGANIC ANIONS

Inorganic anions-induced fluorescence quenching of seven aromatic amin es has been studied up to 0.1M concentration. The fluorescence intensi ties of all the aromatic amines (except aniline) remain unaffected whe n Cl- and SCN- are used as quenchers, whereas sufficient decrease in t he fluorescence intensities is noticed when Br- and I- are used as que nchers. Based on the results obtained in the case of aniline, the fluo rescence quenching efficiency of the anions can be ordered as: SCN- <B r- <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 k(q) cannot be correlat ed with the spin-orbit; coupling constants of the quencher atom when a niline is considered.