Fluorescence quenching of anthrylvinyl acetate by carbon tetrachloride

Fluorescence quenching of anthrylvinyl acetate by carbon tetrachloride (CCl4) was carried out in both polar and non-polar solvents at room temperature to understand the role of quenching mechanism. The negative deviation in normal Stern-Volmer (S-V) plots was observed in almost all solvents used for lambda(ex), 345 nm, 365 nm and 385 nm. The bimolecular quenching rate constant (k(q)) estimated using the measured values of quenching constants and decay times were found to be dependent on the polarity of the solvent. Further, it is found that quenching efficiency increases with increasing polarity of the solvent. The negative deviations from the normal Stern-Volmer (S-V) plots shown in the fluorescence quenching of anthrylvinyl acetate by carbon tetrachloride is interpreted in terms of the existence of different conformers of the solute in the ground-state. Fluorescence decay of the solute before quenching showed bi-exponential behavior and the analysis yielded two decay components, respectively, in the range 2.11-7.22 ns and 5.17-12 ns in all solvents except n-propanol and methanol. Based on the steady state and fluorescence lifetime measurements emission band I (408 nm) is assigned due to locally (LE) excited state (Trans form), band II (430 nm) due to isomer state of Cis form. (C) 2010 Elsevier B.V. All rights reserved.