Fluorescence quenching of 6BDTC by aniline in different solvents

Abstract

Quenching mechanisms of coumarin derivative 6-bromo-3-[1-(4,5-dicarbomethoxy-1,2,3-triazoloacetyl)]coumarin (6BDTC) were carried out in different solvents using the steady-state method to understand the role of diffusion in the quenching mechanism. The solute was excited by UV radiation of wavelength 360 nm. Various quenching parameters like frequency of encounter, kd; probability of quenching per encounter, p; and quenching rate parameter, kq, were experimentally determined for all solvents. Activation energies of quenching, Ea, were also determined by using the literature values of activation energy of diffusion, Ed. It was found that the values of Ea were less than Ed in all solvents indicating that the quenching reactions are more significantly influenced by material diffusion.

Exploring the mechanism of fluorescence quenching in two biologically active boronic acid derivatives using Stern-Volmer kinetics

“…Quenching studies can reveal, for example, the diffusion rate of quenchers, localization of fluorophores in proteins and membranes and their accessibilities to quenchers. Because of many such novel applications, fluorescence quenching study has attracted many investigators in the last couple of decades [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. One of the well-known experimental techniques used to study the fluorescence quenching is to determine some of the quenching parameters using Stern-Volmer plots.…”

Fluorescence quenching of boronic acid derivatives by aniline in alcohols – A Negative deviation from Stern–Volmer equation

“…The diffusion coefficients are calculated using Stokes-Einstein equation [26] D kT a R 8 πη = ( ) here k is Boltzmann constant, T is the absolute temperature, η is the solvent viscosity (in cP), R is the radius of solute or quencher molecule as the case may be and 'a' is Stoke-Einstein number. Its value is 6 for solute and 3 for quencher [8]. The calculated values of k q and k d for both the solutes are tabulated in Tables 1 and 2.…”

“…Here N ′ is Avogadro number in per millimole, D ¼D S þ D Q and R¼ R S þR Q represents the sum of the diffusion coefficients (in cm 2 s À 1 ) and the molecular radii (in Å) of the solute (S) and the quencher (Q), respectively [8,25]. The diffusion coefficients are calculated using Stokes-Einstein equation [26] D kT a R 8 πη = ( ) here k is Boltzmann constant, T is the absolute temperature, η is the solvent viscosity (in cP), R is the radius of solute or quencher molecule as the case may be and 'a' is Stoke-Einstein number.…”

“…The efficient quenching may take place before the complete formation of an exciplex/conformer and the diffusion limited quenching is expected to increase with the decrease in solvent viscosity. In order to understand the effect of solvent viscosity (η), the diffusion-limited rate constant k d is estimated using the following equation [8]:…”

“…Quenching studies can reveal for example the diffusion rate of quenchers, localization of fluorophores in proteins and membranes and their permeabilities to quenchers. Because of many such novel applications, fluorescence quenching study has attracted many investigators in the last couple of decades [1][2][3][4][5][6][7][8][9][10][11]. The mechanism of decreasing the fluorescence intensity of a given substance is known as fluorescence quenching.…”