Effect of viscosity and dielectric constant variation on fractional fluorescence quenching analysis of coumarin dye in binary solvent mixtures

Abstract

Photo physical properties of fluorescent organic compounds give an immense improved knowledge on characteristics of excited state that is beneficial to devise innovate molecules and understand their performance in particular applications. Coumarin derivatives have been extensively investigated in this regard. This article narrates steady state fluorescence quenching measurements of a coumarin derivative namely 3-hydroxy-3-[2-oxo-2-(3-oxo-3H-benzo[f]chromen-2-yl)-ethyl]-1,3-dihydro-indol-2-one (3HBCD) in a binary mixture of acetonitrile and 1,4-dioxane. Aniline is used as quencher. Fluorescence intensity is large in acetonitrile and decreases as the percentage of 1,4-dioxane in the solvent mixture increases. With modest quencher concentration a deviation towards the x axis is noticed in the Stern-Volmer (S-V) plots. This downward curvature is interpreted as due to the presence of 3HBCD in different conformers in the lowest energy level. Ground state intramolecular hydrogen bonding formation is observed due to the conformational changes in the solute. Figured estimations of various quenching parameters recommend that, while dynamic quenching prompts linearity in S-V plot at lower quencher concentration, increasing quenching efficiency with increasing medium viscosity suggests that reaction is not entirely controlled by material diffusion. Stern-Volmer constant increases with decreasing medium dielectric constant.

Effect of preferential solvation and bimolecular quenching reactions on 3OCE in acetonitrile and 1,4‐dioxane binary mixtures by optical absorption and fluorescence studies

“…In some cases, it has been observed that certain quenching reactions give curved S–V plots. Both upward and downward curves have been observed by many researchers. While positive curvature is associated with various processes such as combined static and dynamic quenching, intersystem crossing, or the formation of charge transfer complexes at ground and excited states, negative curvature in S–V plots is due to the heterogeneity of the system, selective quenching, hydrogen bond complex formation, or occurrence of a reversible photochemical process.…”

Isomeric Effect on the anticancer Behavior of two Zinc (II) complexes based on 3,5‐bis(1‐imidazoly) pyridine: Experimental and Theoretical Approach

“…The K sq value can be used to quantitatively determine the ability of the complex to interact with the DNA under the same conditions. The greater the K sq value, the stronger the ability . The emission spectra of EtBr bound to DNA in the absence and presence of the two complexes and the fluorescence‐quenching curve are shown in Figure .…”

Effect of Hydrogen Bonding on Fluorescence Quenching of Quinolin-8-Ol - Analysis Using Negative Stern-Volmer Plots

“…Data related to positive S-V plot is pursued using modified S-V equations 15 . Negative deviation of S-V plots (downward curvature) is also reported by many researchers 10,13,14,16 . Many Reasons such as heterogeneity of the system, selective quenching, hydrogen bond complex formation, occurrence of reverse reaction in photochemical process etc are identified for the negative deviation.…”

“…Many Reasons such as heterogeneity of the system, selective quenching, hydrogen bond complex formation, occurrence of reverse reaction in photochemical process etc are identified for the negative deviation. Quenching data which are expected to arise from one of these reasons may be represented by modified 'SternVolmer' equation or Lehrer equation 10,17,18 given below. In the present paper we report the quenching of a newly synthesized Quinolin-8-ol (QO) in toluene and butanol solvents.…”

“…New fluorescent probes have been suggested 8,9 . Because of many such novel applications, many investigators have taken up this study [10][11][12][13][14] .…”