Sulochana Devar¹, S.M. Basavarajaiah², G.Y. Nagesh³, S.M. Hanagodimath^1
1Department of PG Studies and Research in Physics, Gulbarga University, Kalaburagi-585 106, Karnataka, India
²PG Department of Chemistry, Vijaya College, R. V. Road, Bengaluru-560004, Karnataka, India
³Department of Chemistry, Guru Nanak First Grade College, Bidar, Karnataka, India

Abstract. The fluorescence quenching of the newly synthesized indole derivative Ethyl 5-Methyl-3-phenyl-1H-indole 2-Carboxylate [5-MPIC], has been examined in various solvents, including Benzene, Tolu\-ene, 1,4 Dioxane, Acetonitrile. Aniline was used as a quencher. The molecular behavior in various media has been explored by using solvents with different refractive index and dielectric constants. Spectroscopic techniques like UV/Vis spectroscopy and time-resolved single-photon counting were utilized to characterize the molecules at room temperature. The study of fluorescence quenching demonstrated a linear dependence in Stern-Volmer (SV) plots across solvents with varying dielectric constants. This indicates that the quenching reactions are dynamic. Additionally, key quenching parameters were determined, and the specific type of quenching reaction involved was identified. at room temperature, and the study took into account the role of diffusion in the quenching process. The probability of quenching per encounter (p) was calculated for all solvents. Furthermore, the values of p were used to estimate both the activation energy for quenching and the activation energy for diffusion.

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