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

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.

2013 ◽  
Vol 12 (1) ◽  
pp. 87-98
Author(s):  
J Thipperudrappa ◽  
S M Hanagodimath

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.


Author(s):  
Ashok H. Sidarai ◽  
Vani R. Desai ◽  
Shirajahammad M. Hunagund ◽  
Mahantesha Basanagouda ◽  
Jagadish S. Kadadevarmath

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.


2014 ◽  
Vol 92 (1) ◽  
pp. 41-45 ◽  
Author(s):  
N.R. Patil ◽  
R.M. Melavanki

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.


2013 ◽  
Vol 12 (1) ◽  
pp. 69-85 ◽  
Author(s):  
R M Melavanki ◽  
N R Patil ◽  
D Nagaraja ◽  
H D Patil ◽  
J S Kadadevarmath ◽  
...  

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.


2021 ◽  
Vol 22 (2) ◽  
pp. 885
Author(s):  
Krzysztof Żamojć ◽  
Irena Bylińska ◽  
Wiesław Wiczk ◽  
Lech Chmurzyński

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.


2021 ◽  
Author(s):  
C. Manivannan ◽  
S. Baskaran ◽  
Anbazhagan V

Abstract The photoinduced interaction of nile blue (NB) with various antioxidant molecules was investigated by fluorescence quenching technique and lifetime measurements. The various substituted catecholic compounds are employed as quenchers to evaluate their antioxidant activity. The formations of ground state complex between NB and quencher molecules observed from the UV-Visible absorption spectroscopy. The bimolecular quenching rate constants (kq) values depend on presence of substituent and its electronic properties of quencher molecules. Fluorescence quenching experiments have been performed at three different temperatures to assess the thermodynamic parameters. Time resolved fluorescence measurements suggest that the fluorescence quenching of NB with antioxidant molecules undergoes static quenching mechanism. The bond dissociation enthalpy (BDE) values reveal the discharge of HTfrom the antioxidant molecules. The electronic properties play an important role in the antioxidant activity of quencher molecules. The mechanism of fluorescence quenching between NB and quencher molecules are analysed based on the fluorescence quenching experiments, cyclic voltammetry experiments and BDE calculations.


2014 ◽  
Vol 92 (4) ◽  
pp. 302-306 ◽  
Author(s):  
H.R. Deepa ◽  
J. Thipperudrappa ◽  
H.M. Suresh Kumar

The energy transfer using two laser dyes 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoromethyl)-2H-pyrano[2,3-b][1,8]naphthyridin-2-one (LD-489) and 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) as donors and rhodamine 6G (Rh6G) as acceptor was investigated in methanol using steady state and time resolved fluorescence spectroscopy. The bimolecular quenching rate parameter, kq, and the translation diffusion rate parameter, kd, were calculated and these values indicated that the diffusion process alone does not operate in energy transfer process. The mean diffusion length, d1, is found to be less than the Förster distance, R0, supporting the dominance of long-range interaction. The critical transfer distances determined from both the Förster equation and the half quenching concentration are close to one another, revealing that the Förster mechanism plays an important role in overall energy transfer of the donors.


2014 ◽  
Vol 92 (2) ◽  
pp. 163-167 ◽  
Author(s):  
H.R. Deepa ◽  
H.M. Suresh Kumar ◽  
M. Basanagouda ◽  
J. Thipperudrappa

The interaction of silver nanoparticles with four laser dyes, namely, LD-425, LD-489, LD-473, and LD-423, dispersed in methanol has been studied at room temperature by absorption and fluorescence spectroscopy. The silver nanoparticles were synthesized by chemical reduction and estimated size is 11 nm according to Mie theory. The changes in absorption spectrum of these dyes with the addition of silver nanoparticles suggest possible interaction with the silver nanoparticles. The magnitudes of the association constants are estimated using the Benesi–Hildebrand model. Fluorescence quenching has been observed for all the dyes with the addition of silver nanoparticles of different concentrations. The Stern–Volmer plots of fluorescence quenching in the case of LD-425 and LD-489 are found to be linear, suggesting the fluorescence quenching is because of the dynamic quenching process. But in the case of LD-473 and LD-423, the Stern–Volmer plots are nonlinear showing positive deviation and the fluorescence quenching in these dyes is because of static quenching processes. Also, it is found that the fluorescence quenching is not solely due to diffusion.


2015 ◽  
Vol 93 (10) ◽  
pp. 1076-1081 ◽  
Author(s):  
Shivaram N. Patil ◽  
F.M. Sanningannavar ◽  
B.S. Navati ◽  
D. Nagaraja ◽  
N.R. Patil ◽  
...  

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.


2017 ◽  
Vol 231 (5) ◽  
Author(s):  
Chandrakumar Manivannan ◽  
Rajadurai Vijay Solomon ◽  
Ponnambalam Venuvanalingam ◽  
Rajalingam Renganathan

AbstractThe influence of phenols upon the fluorescence quenching of 9-aminoacridine (9-AA) was examined in acetonitrile solution by employing steady state and time-resolved fluorescence measurements. On increasing the concentration of quencher molecules the absorption spectra of 9-AA change with significant bathochromic shift. The fluorescence intensity of 9-AA change in presence of quencher molecules were measured at various temperatures as a function of the quencher concentrations. The observed bimolecular quenching rate constant (k


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