Abstracto

Fluorescence quenching of 5-methyl-2-phenylindole by carbon tetrachloride

S.V.Nishti, R.S.Kunabenchi, O.V.Mangalgi, H.M.Suresh Kumar, S.M.Praveen, J.S.Biradar

The steady state fluorescence quenching of 5-methyl-2-phenylindole by carbon tetrachloride in different solvents viz. dioxane, benzene, toluene, butanol, methanol and acetonitrile, and time dependent study in butanol solvent has been carried out at room temperature with a view to understand the quenching mechanisms. The experimental results show positive deviation in the Stern-Volmer plot in all the solvents. The quencher concentration dependence data were analyzed using ground state complex formation and sphere of action static quenching models in order to interpret the results. The various rate parameters have been determined and the magnitudes of these rate parameters suggest that the ground state complex formation model is not applicable in this case but the sphere of action static quenching model agrees well with the experimental results. Hence, both the static and dynamic quenching processes are responsible for the observed positive deviation in the Stern-Volmer plots. Further, with the use of finite sink approximationmodel, it is concluded that these bimolecular quenching reactions are diffusion limited, and also the dependence of Stern-Volmer constant on dielectric constant of the solvents suggest the charge transfer character of the excited complex.