Role of solvent polarity on fluorescence quenching of 3MOCE in binary solvent mixtures

The fluorescence quenching of 3-[2-(8-Methoxy-2-oxo-2H-chromen-3-yl)-2-oxo-ethylidene]-1,3-dihydro-indol-2-one [3MOCE] coumarin by aniline has been studied in different solvent mixtures of 1-4 Dioxane (DX) and acetonitrile (AN) at room temperature. The quenching is found to be appreciable and a positive deviation from linearity was observed in the Stern– Volmer (S–V) plot in all the solvent mixtures. Various parameters for the quenching process have been determined by sphere of action static quenching model and finite sink approximation model. The magnitudes of these rate parameters indicate that positive deviation in the S–V plot is due to both static and dynamic processes.