title: Solvent effect on the relative quantum yield and fluorescence quenching of a newly synthesized coumarin derivative.
abstract: We estimated the relative florescence quantum yield (Φ) of 8-methoxy-3-[1-(4,5-dicarbomethoxy-1,2,3-triazoloacetyl)]coumarin [8MDTC] using a single-point method with quinine sulfate in 0.1 M of sulfuric acid used as a standard reference. The fluorescence lifetimes, radiative and non-radiative decay rate constants are calculated. Relative quantum yields were found to be less in the non-polar solvents, indicating that the solute exhibits less fluorescence in a non-polar environment. The fluorescence quenching of [8MDTC] by aniline was studied at room temperature by examining the steady state in five different solvents in order to explore various possible quenching mechanisms. The experimental results show a positive deviation in Stern-Volmer plots in all solvents. Ground state complex and sphere of action static quenching models were used to interpret the results. Many quenching rate parameters were calculated using these models. The values of these parameters suggest that the sphere of action static quenching model agrees well with the experimental results. Further, a finite sink approximation model was used to check whether these bimolecular reactions were diffusion limited or not. The values of the distance parameter R' and the diffusion coefficient D were determined and are compared with the values of the encounter distance R and diffusion coefficient D calculated using the Stokes-Einstein equation.
authors.affiliation: Department of Physics, Bangalore Institute of Technology, Bangalore, 560004, Karnataka, India.
authors.forename: D
authors.initials: D
authors.lastname: Nagaraja
authors.affiliation: Department of Physics, M S Ramaiah Institute of Technology, Bangalore, 560054, Karnataka, India.
authors.forename: R M
authors.initials: RM
authors.lastname: Melavanki
authors.affiliation: Department of Physics, B V B College of Engineering and Technology, Hubli, 580031, Karnataka, India.
authors.forename: N R
authors.initials: NR
authors.lastname: Patil
authors.affiliation: Department of Physics, Bangalore Institute of Technology, Bangalore, 560004, Karnataka, India.
authors.forename: H S
authors.initials: HS
authors.lastname: Geethanjali
authors.affiliation: Department of Chemistry, R. V. College of Engineering, Bangalore, 560059, Karnataka, India.
authors.forename: R A
authors.initials: RA
authors.lastname: Kusanur
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D003374:Coumarins / Q000737:chemistry*; D005453:Fluorescence; D008956:Models, Chemical; D011803:Quinine / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014050:Toluene / Q000737:chemistry
chemical_list: D000814:Aniline Compounds; D003374:Coumarins; D014050:Toluene; D011803:Quinine; C023650:aniline
keywords: [8MDTC]; fluorescence quenching; relative quantum yield; static and dynamic quenching