The fluorescence Quenching Study of Quinine in Presence of Some Anions

The quenching of quinine fluorescence intensity in the presence of some anions in aqueous solution at ambient temperature has been investigated. The quenching is found to be collisional or dynamical in nature. This study reveals the order of two groups of quencher: NaI > NaBr > NaCl > NaF and K2Cr2O7 > KMnO4 >Na2SO4 > NaClO3. Increasing anion size in the both groups leads to an  increase in the quenching due to deactivation processes. As heavy and multi-core anions have greater influence on the quinine’s fluorescence than light halide anions and NaF hasn’t any effect on the fluorescence intensity. The quenching follows linear Stern–Volmer relation. The values of  Stern–Volmer quenching constants/quenching efficiencies (Ksv) for the anions were found to be 2385, 436, 354, 0, 1398, 853, 238, 218 M-1 respectively. Statistical analysis by linear regression method confirms significant different among the values of Stern–Volmer quenching constants.