scholarly journals Solvent Effect on Fluorescence Quenching of 7, 8 Benzo‑4‑azido Methyl Coumarin by Aniline

2013 ◽  
Vol 12 (1) ◽  
pp. 69-85 ◽  
Author(s):  
R M Melavanki ◽  
N R Patil ◽  
D Nagaraja ◽  
H D Patil ◽  
J S Kadadevarmath ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Empirical Relation ◽  
Biologically Active ◽  
Static Quenching ◽  
Einstein Relation ◽  
Positive Deviation ◽  
Quenching Rate ◽  
R And D ◽  
Diffusion Limited ◽  
Static And Dynamic Quenching

Fluorescence quenching of biologically active studies of 7, 8 benzo-4-azidomethyl coumarin (7BAMC) by aniline in four different organic solvents namely benzene, dioxane, tetrahydrofuran and acetonitrile has been carried out at room temperature with a view to understand the quenching mechanisms. The Stern–Volmer (S-V) plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the ground state complex formation and sphere of action static quenching models. Using these models various quenching rate parameters have been determined. The magnitudes of these parameters suggest that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation is attributed to the static and dynamic quenching. Further, with the use of Finite Sink approximation model, it was possible to check these bimolecular reactions as diffusion-limited and to estimate independently distance parameter R’ and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R’ and D with the values of the encounter distance R and the mutual coefficient D determined using the Edward’s empirical relation and Stokes – Einstein relation.

Effect of fluorescence quenching on 6BAAC in different solvents

2014 ◽  
Vol 92 (1) ◽  
pp. 41-45 ◽  
Author(s):  
N.R. Patil ◽  
R.M. Melavanki
Keyword(s):  
Fluorescence Quenching ◽  
Empirical Relation ◽  
Static Quenching ◽  
Einstein Relation ◽  
Positive Deviation ◽  
Quenching Rate ◽  
R And D ◽  
Diffusion Limited ◽  
Quenching Mechanisms ◽  
Static And Dynamic Quenching

The fluorescence quenching studies of 6-bromo-3-azidoacetyl coumarin (6BAAC) by aniline in four different solvents, namely acetonitrile, benzene, dioxane, and toluene, were carried out at room temperature to understand quenching mechanisms. The Stern–Volmer plots have been found to be nonlinear with a positive deviation for all the solvents studied. To interpret these results we have invoked the ground state complex formation and sphere of action static quenching models. Using these models various quenching rate parameters have been determined. The magnitudes of these parameters suggest that the sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation is attributed to the static and dynamic quenching. Further, with the use of the finite sink approximation model, it was possible to check these bimolecular reactions as diffusion-limited and to estimate independently distance parameter R′ and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R′ and D with the values of the encounter distance R and the mutual coefficient D determined using Edward’s empirical relation and the Stokes–Einstein relation.

Quenching mechanism of 5BDTC by aniline using Stern–Volmer plots

2015 ◽  
Vol 93 (10) ◽  
pp. 1076-1081 ◽  
Author(s):  
Shivaram N. Patil ◽  
F.M. Sanningannavar ◽  
B.S. Navati ◽  
D. Nagaraja ◽  
N.R. Patil ◽  
...  
Keyword(s):  
Empirical Relation ◽  
Static Quenching ◽  
Einstein Relation ◽  
Dimethyl Formamide ◽  
Positive Deviation ◽  
Quenching Mechanism ◽  
Quenching Rate ◽  
R And D ◽  
Diffusion Limited ◽  
Static And Dynamic Quenching

The quenching mechanism of 5,6-benzo-3-[1-(4,5-dicarbomethoxy-1,2,3-triazoloacetyl)] coumarin (5BDTC) by aniline using Stern–Volmer plots in six different solvents, namely, 1,4 dioxane, dimethyl formamide, dichloromethane, toluene, tetrahydrofuran, and acetonitrile. The Stern–Volmer plots are found to be nonlinear with a positive deviation in all six solvents. To interpret these results we have invoked ground-state complex formation and sphere of action static quenching models. Using these models, various quenching rate parameters have been determined. The magnitudes of these parameters suggest that the sphere of action static quenching model agrees well with the experimental results. Hence, the positive deviation is attributed to the static and dynamic quenching. Further, with the use of the finite sink approximation model, it was possible to check these bimolecular reactions as diffusion-limited and to estimate independently distance parameter R′ and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R′ and D with the values of the encounter distance R and the mutual coefficient D determined using Edward’s empirical relation and the Stokes–Einstein relation.

A study on fluorescence quenching of a laser dye by aromatic amines in alcohols

2015 ◽  
Vol 93 (4) ◽  
pp. 469-474 ◽  
Author(s):  
H.R. Deepa ◽  
J. Thipperudrappa ◽  
H.M. Suresh Kumar
Keyword(s):  
Fluorescence Quenching ◽  
Aromatic Amines ◽  
Room Temperature ◽  
Static Quenching ◽  
Laser Dye ◽  
Approximation Model ◽  
Positive Deviation ◽  
Quenching Rate ◽  
Time Resolved ◽  
Bimolecular Quenching

The fluorescence quenching of 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) by aromatic amines, namely, aniline, dimethyl aniline, and diethyl aniline, in methanol, ethanol, propanol, and butanol has been studied at room temperature using steady-state and time-resolved methods. A positive deviation from linearity has been observed in Stern–Volmer (S–V) plots. Various quenching rate parameters have been determined using the extended S–V equation and are found to be dependent on the dielectric constant of alcohols. The quenching ability of amines increases with increasing their ionization energies. Further, with the use of the sphere of action, static quenching model, and finite sink approximation model, it is concluded that the bimolecular quenching reactions are due to the combined effect of both dynamic and static quenching processes.

scholarly journals Fluorescence Quenching of DMB by Aniline in Benzene-Acetonitrile Mixture

2016 ◽  
Vol 65 ◽  
pp. 32-36 ◽  
Author(s):  
Ashok H. Sidarai ◽  
Vani R. Desai ◽  
Shirajahammad M. Hunagund ◽  
Mahantesha Basanagouda ◽  
Jagadish S. Kadadevarmath
Keyword(s):  
Fluorescence Quenching ◽  
Room Temperature ◽  
Solvent Mixture ◽  
Static Quenching ◽  
Solvent Mixtures ◽  
Dynamic Quenching ◽  
Approximation Model ◽  
Positive Deviation ◽  
Coumarin Dye ◽  
Static And Dynamic Quenching

The fluorescence quenching of coumarin dye namely 4-(2,6-dibromo-4-methyl-phenoxymethyl)-benzo[h]chromen-2-one [DMB] has been studied by aniline, in a different solvent mixture of benzene (BN) and acetonitrile (AN) at room temperature. The quenching is found to be appreciable and shows positive deviation from linearity in the Stern-Volmer (S-V) plots for all the solvent mixtures. The various rate parameters responsible for fluorescence quenching have been determined using a sphere of action static quenching model and finite sink approximation model. The magnitudes of these rate parameters indicate that positive deviation in the S-V plot is due to both static and dynamic quenching processes.

Fluorescence quenching of a biologically active boronic acid derivative by aniline in different solvents

2018 ◽  
Vol 96 (6) ◽  
pp. 603-609 ◽  
Author(s):  
Raveendra M. Melavanki
Keyword(s):  
Fluorescence Quenching ◽  
Boronic Acid ◽  
Biologically Active ◽  
Fluorescent Properties ◽  
Quenching Rate ◽  
Diffusion Limited ◽  
Fluorescence Measurements ◽  
Wide Range ◽  
Boronic Acid Derivatives ◽  
Fluorescent Molecules

Boronic acid derivatives are novel biologically active fluorescent molecules with numerous applications in various fields. A study of their fluorescent properties reveals some information that can be utilized in sensor design. One such study is fluorescence quenching. Here fluorescence quenching of 2-methoxypyridin-3-yl-3-boronic acid (2MPBA) in different solvents of a wide range of polarities has been carried out at room temperature by steady state fluorescence measurements. Aniline is used as the quencher. The positive deviation observed in Stern–Volmer (S-V) plots is analyzed using different quenching models. Various quenching parameters like S-V constant (KSV), quenching rate parameter (kq), volume constant (V), and kinetic distance (r) have been estimated using extended S-V equations. KSV is found to vary from 12.94 to 62.49 (mol/L)−1 with respect to solvents. From the calculated values of these parameters it is concluded that the static quenching mechanism is active in the studied system. However the reactions are diffusion-limited, which is confirmed by invoking the finite sink approximation model.

scholarly journals Analysis of Fluorescence Quenching of BPBD by Aniline in Toluene

2013 ◽  
Vol 12 (1) ◽  
pp. 87-98
Author(s):  
J Thipperudrappa ◽  
S M Hanagodimath
Keyword(s):  
Steady State ◽  
Fluorescence Quenching ◽  
Room Temperature ◽  
Static Quenching ◽  
Approximation Model ◽  
Positive Deviation ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Steady State Method ◽  
Volmer Plot

Fluorescence quenching of 2-(4'-t-Butylphenyl)-5-(4"-biphenylyl)-1,3,4-oxadiazole (BPBD) by aniline in toluene has been carried out at room temperature by steady state and time resolved fluorescence spectroscopy. The Stern-Volmer plot by steady state method has been found to be non-linear showing a positive deviation, whereas by time-resolved method it is linear. In order to interpret these results we have used the ground state complex and sphere of action static quenching models. Using these models various rate parameters have been determined. Based on these models, with finite sink approximation model, we conclude that positive deviation Stern-Volmer plot is due to the simultaneous presence of dynamic and static quenching processes.

Effect of solvent polarity on the fluorescence quenching of TMC molecule by aniline in benzene–acetonitrile mixtures

2016 ◽  
Vol 94 (11) ◽  
pp. 1125-1132 ◽  
Author(s):  
Ashok H. Sidarai ◽  
Vani R. Desai ◽  
Shirajahammad M. Hunagund ◽  
Mahantesha Basanagouda ◽  
Jagadish S. Kadadevarmath
Keyword(s):  
Fluorescence Quenching ◽  
Rate Constants ◽  
Transient State ◽  
Solvent Polarity ◽  
Coumarin Derivative ◽  
Solvent Mixtures ◽  
Positive Deviation ◽  
Diffusion Limited ◽  
Quenching Process ◽  
Volmer Plot

The fluorescence quenching of coumarin derivative, 6-methoxy-4-p-tolyloxymethyl-chromen-2-one by aniline is carried out in different solvent mixtures of benzene and acetonitrile at room temperature. The quenching is found to be appreciable and a positive deviation from linearity is observed in the Stern–Volmer plot in all the solvent mixtures. Various rate constants for fluorescence quenching processes have been estimated using a sphere of action static quenching model and a finite sink approximation model. From the positive deviation of linear Stern–Volmer plots and dependence of rate constants on the polarity of the solvents, it has been inferred that the quenching process is diffusion-limited, and static as well as dynamic quenching processes are responsible for the observed positive deviation in the Stern–Volmer plot. Further, both models have been found to agree well with transient state also in pure acetonitrile and benzene solvents.

scholarly journals Fluorescence Quenching Studies on the Interactions between Chosen Fluoroquinolones and Selected Stable TEMPO and PROXYL Nitroxides

2021 ◽  
Vol 22 (2) ◽  
pp. 885
Author(s):  
Krzysztof Żamojć ◽  
Irena Bylińska ◽  
Wiesław Wiczk ◽  
Lech Chmurzyński
Keyword(s):  
Fluorescence Quenching ◽  
Rate Constants ◽  
Quenching Rate ◽  
Time Resolved ◽  
Radiative Processes ◽  
Diffusion Limited ◽  
Fluoroquinolone Antibiotics ◽  
Quenching Efficiency ◽  
Bimolecular Quenching ◽  
The Impact

The influence of the stable 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO) nitroxide and its six C4-substituted derivatives, as well as two C3-substituted analogues of 2,2,5,5-tetramethylpyrrolidynyl-N-oxyl (PROXYL) nitroxide on the chosen fluoroquinolone antibiotics (marbofloxacin, ciprofloxacin, danofloxacin, norfloxacin, enrofloxacin, levofloxacin and ofloxacin), has been examined in aqueous solutions by UV absorption as well as steady-state and time-resolved fluorescence spectroscopies. The mechanism of fluorescence quenching has been specified and proved to be purely dynamic (collisional) for all the studied systems, which was additionally confirmed by temperature dependence experiments. Moreover, the selected quenching parameters—that is, Stern–Volmer quenching constants and bimolecular quenching rate constants—have been determined and explained. The possibility of electron transfer was ruled out, and the quenching was found to be diffusion-limited, being a result of the increase in non-radiative processes. Furthermore, as the chosen nitroxides affected the fluorescence of fluoroquinolone antibiotics in different ways, an influence of the structure and the type of substituents in the molecules of both fluoroquinolones and stable radicals on the quenching efficiency has been determined and discussed. Finally, the impact of the solvent’s polarity on the values of bimolecular quenching rate constants has been explained. The significance of the project comes from many applications of nitroxides in chemistry, biology and industry.

Fluorescence Quenching of Aminodiphenylamines with Chloromethanes

2002 ◽  
Vol 67 (8) ◽  
pp. 1154-1164 ◽  
Author(s):  
Nachiappan Radha ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Charge Transfer ◽  
Fluorescence Quenching ◽  
Ground State ◽  
Rate Constants ◽  
Quenching Mechanism ◽  
Quenching Rate ◽  
Charge Transfer Interaction ◽  
Electronically Excited ◽  
A Charge

The fluorescence quenching of 2-aminodiphenylamine (2ADPA), 4-aminodiphenylamine (4ADPA) and 4,4'-diaminodiphenylamine (DADPA) with tetrachloromethane, chloroform and dichloromethane have been studied in hexane, dioxane, acetonitrile and methanol as solvents. The quenching rate constants for the process have also been obtained by measuring the lifetimes of the fluorophores. The quenching was found to be dynamic in all cases. For 2ADPA and 4ADPA, the quenching rate constants of CCl4 and CHCl3 depend on the viscosity, whereas in the case of CH2Cl2, kq depends on polarity. The quenching rate constants for DADPA with CCl4 are viscosity-dependent but the quenching with CHCl3 and CH2Cl2 depends on the polarity of the solvents. From the results, the quenching mechanism is explained by the formation of a non-emissive complex involving a charge-transfer interaction between the electronically excited fluorophores and ground-state chloromethanes.

A Fluorescence Quenching Analysis of the Binding of Fluoroquinolones to Humic Acid

2017 ◽  
Vol 71 (11) ◽  
pp. 2512-2518 ◽  
Author(s):  
Ryan P. Ferrie ◽  
Gregory E. Hewitt ◽  
Bruce D. Anderson
Keyword(s):  
Humic Acid ◽  
Fluorescence Quenching ◽  
Water Solubility ◽  
Binding Constants ◽  
High Water ◽  
Static Quenching ◽  
Temperature Range ◽  
Equilibrium Binding ◽  
Quenching Analysis ◽  
High Water Solubility

Fluorescence quenching was used to investigate the interaction of six fluoroquinolones with humic acid. Static quenching was observed for the binding of ciprofloxacin, enoxacin, fleroxacin, levofloxacin, norfloxacin, and ofloxacin to humic acid. The equilibrium binding constants were found from Stern–Volmer plots of the data. The quenching experiments were repeated over a temperature range of 25–45 ℃ and van’t Hoff plots were generated. From these linear plots, thermodynamic values were calculated for Δ H, Δ G, and Δ S for each of the fluoroquinolones. The equilibrium binding constants were found to be <1 for all the antibiotics studied. The calculated ΔH values were all negative and ranged from −9.5 to −27.6 kJ/mol. The high water solubility of the antibiotics and low ΔH of binding suggests that the antibiotics will be transported easily through the environment. Finally, whether the fluoroquinolones are in a protonated, deprotonated, or partially protonated state is found to correlate to the strength of binding to humic acid.

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