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Journal articles on the topic 'Stern-Volmer'

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Published: 4 June 2021
Last updated: 10 March 2023

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1

Green, Nicholas J. B., Simon M. Pimblott, and M. Tachiya. "Generalizations of the Stern-Volmer relation." Journal of Physical Chemistry 97, no. 1 (January 1993): 196–202. http://dx.doi.org/10.1021/j100103a034.

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2

Sidarai, Ashok H., Vani R. Desai, Shirajahammad M. Hunagund, Mahantesha Basanagouda, and Jagadish S. Kadadevarmath. "Effect of solvent polarity on the fluorescence quenching of TMC molecule by aniline in benzene–acetonitrile mixtures." Canadian Journal of Physics 94, no. 11 (November 2016): 1125–32. http://dx.doi.org/10.1139/cjp-2016-0213.

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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.
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3

Moore, Stephanie A., Sarah E. Moore, Karen M. Glenn, Subhash C. Bhattacharya, and Rama M. Palepu. "Fluorescence quenching of Safranine T by inorganic anions in Tween micelles." Canadian Journal of Chemistry 83, no. 12 (December 1, 2005): 2067–72. http://dx.doi.org/10.1139/v05-225.

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The fluorescence quenching of the dye Safranine T by various inorganic anions such as [Fe(CN6)]–3, [Fe(CN6)]–4, I–, Br–, NO2–, and N3– in aqueous solution and in nonionic micellar solutions of Tweens (Tween 20, Tween 40, and Tween 80) was studied. The Stern–Volmer quenching constants and quenching rate constants were evaluated. Compared to the quenching efficiency in aqueous media, that of the micellar media was found to be lower, except when iodide ion was used as a quencher. With the exception of the iodide ion, it has been established that collisional quenching plays a major role in the photophysical process. In the case of the iodide ion, both static and collisional quenching processes play a major role, owing to the complexation of iodide ion with Tween micelles. The Stern–Volmer quenching constants were found to be dependent on the ionic strength of the medium.Key words: fluorescence, static quenching, Tweens, Stern–Volmer constant, micellar media.
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4

Blatt, E., AWH Mau, WHF Sasse, and WH Sawyer. "Simulated Stern-Volmer Plots for 1-1 Ground-State Complexation." Australian Journal of Chemistry 41, no. 1 (1988): 127. http://dx.doi.org/10.1071/ch9880127.

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Stern-Volmer plots are simulated for the case of static quenching due to 1:1 ground-state complexation of quencher and fluorophore in solution, and compared with previously obtained experimental data. For cases where the association constant KC > 105 dm3 mol-1, upward curvatures of Stern- Volmer plots are expected. When KC is between 103 and 105 dm3 mol-1 linearity is obtained, while for KC < 103 dm3 mol-1 upward curvatures are again predicted. The significance of these results to fluorescence quenching experiments in general is discussed.
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5

Thipperudrappa, J., and S. M. Hanagodimath. "Analysis of Fluorescence Quenching of BPBD by Aniline in Toluene." Mapana - Journal of Sciences 12, no. 1 (February 13, 2013): 87–98. http://dx.doi.org/10.12723/mjs.24.8.

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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.
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6

Popov, A. V., V. S. Gladkikh, and A. I. Burshtein. "Stern−Volmer Law in Competing Theories and Approximations†." Journal of Physical Chemistry A 107, no. 40 (October 2003): 8177–83. http://dx.doi.org/10.1021/jp030007d.

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7

Ogunsipe, Abimbola, and Tebello Nyokong. "Effects of central metal on the photophysical and photochemical properties of non-transition metal sulfophthalocyanine." Journal of Porphyrins and Phthalocyanines 09, no. 02 (February 2005): 121–29. http://dx.doi.org/10.1142/s1088424605000186.

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The photophysical and photochemical properties and quenching (by 1,4-benzoquinone) of metallophthalocyanine sulfonates of aluminium ( AlPcSmix), zinc ( ZnPcSmix), silicon ( SiPcSmix), germanium ( GePcSmix) and tin ( SnPcSmix) are presented. The quantum yield values of fluorescence (ΦF), triplet state (ΦT), singlet oxygen (ΦΔ) and photodegradation (Φd) were determined and the observed trends in their variation among the complexes discussed in terms of aggregation and the heavy atom effect. 1,4-benzoquinone effectively quenched the fluorescence of the complexes. Quenching analyses gave positive deviations from Stern-Volmer behavior, suggesting the existence of static quenching in addition to dynamic quenching. The static and dynamic components of the quenching were separated using a modified Stern-Volmer equation and the “sphere of action quenching model”. The quenching constant was found to be a function of the radius of the central metal ion.
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8

Castillo, John, and Herminsul Cano. "Study of the fluorescence quenching of 1-hydroxypyrene-3,6,8-trisulfonic acid by single-walled carbon nanotubes." Universitas Scientiarum 22, no. 3 (October 26, 2017): 201. http://dx.doi.org/10.11144/javeriana.sc22-2.sotf.

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This paper presents a study of the fluorescence quenching of 1-hydroxypyrene-3,6,8-trisulfonic acid (HPTS) in the presence of single-walled carbon nanotubes (SWCNT) using a fluorescence method. To investigate the quenching mechanism (dynamic or static) of HPTS, Stern-Volmer plots of single walled carbon nanotubes at different temperatures were used. The positive deviation from linearity in Stern-Volmer plots suggests that single walled carbon nanotubes follow a static quenching mechanism evidenced by the formation of a stable ground state complex. The results presented here help us to clarify the quenching mechanism in the interaction of a pyrene derived dye and carbon nanotubes. This study will open new possibilities in the use of the conjugate formed by SWCNTs and HPTS in the fabrication of a<br />biosensor based on intracellular fluorescent probes.
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9

Acree, William E. "Comments Concerning "The Effect of Temperature on the Fluorescence Quenching of Perylene by Tetrachloromethane in Mixtures with Cyclohexane and Benzene"." Zeitschrift für Naturforschung A 48, no. 12 (December 1, 1993): 1265–66. http://dx.doi.org/10.1515/zna-1993-1221.

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Abstract An indirect spectrofluorometric probe method is developed for calculating equilibrium constants for formation of heterogeneous solvent-solvent molecular complexes from measured fluorescence emission intensities in select systems that exhibit parabolic-shaped Stern-Volmer quenching plots.
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10

Talaat, Wael, Abdelbasset A. Farahat, and Reda Mohammed Keshk. "Selective Sensing of Darolutamide and Thalidomide in Pharmaceutical Preparations and in Spiked Biofluids." Biosensors 12, no. 11 (November 11, 2022): 1005. http://dx.doi.org/10.3390/bios12111005.

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Selective spectrofluorometric sensing is introduced for the analysis of non-steroidal anti-androgens, darolutamide, and thalidomide in pharmaceutical preparations and biofluids. An organic fluorophore, 2,4,8,10-tetramethylpyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidine 2 was synthesized in our laboratories by new simple methods to act as a fluorescent reagent for the analysis of the studied drugs. Elemental and spectral analyses were performed to approve the fluorophore structure. The fluorophore possesses a fluorescence at λem 422 nm when excited at 328 nm. The interaction between the studied drugs and the fluorophore was found to be quenching. The quenching mechanisms were studied and interpreted through the Stern–Volmer relationship. Moreover, the Stern–Volmer constants were calculated for the quenching interactions of both drugs. The introduced method was validated for the estimation of darolutamide and thalidomide in dosage forms, plasma, and urine, offering good percentage recoveries.
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11

Goodpaster, John V., and Victoria L. McGuffin. "Rapid and Accurate Determination of Stern—Volmer Quenching Constants." Applied Spectroscopy 53, no. 8 (August 1999): 1000–1008. http://dx.doi.org/10.1366/0003702991947676.

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12

Desilets, David J., Peter T. Kissinger, and Fred E. Lytle. "Improved method for determination of Stern-Volmer quenching constants." Analytical Chemistry 59, no. 8 (April 15, 1987): 1244–46. http://dx.doi.org/10.1021/ac00135a040.

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13

Zhang, Xiaoxiong, Shaopei Zhang, and Wenjun Zhang. "A novel luminescent hybrid material based on zinc complexes and graphene oxides for detection of Fe3+ in aqueous media." Dalton Transactions 47, no. 39 (2018): 14070–77. http://dx.doi.org/10.1039/c8dt02688b.

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A novel GOS-modified zinc complex probe with water dispersibility is designed to detect Fe3+ in aqueous media (Stern–Volmer constant KSV = 4 × 106 L mol−1).
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14

Qu, Binhong, Zhiyuan Mu, Yang Liu, Yingsha Liu, Rui Yan, Jianhui Sun, Zishu Zhang, Peng Li, and Liqiang Jing. "The synthesis of porous ultrathin graphitic carbon nitride for the ultrasensitive fluorescence detection of 2,4,6-trinitrophenol in environmental water." Environmental Science: Nano 7, no. 1 (2020): 262–71. http://dx.doi.org/10.1039/c9en01165j.

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The porous ultrathin g-C3N4 nanosheets with strong adsorption capacity have been synthesized for the ultrasensitive fluorescence detection of 2,4,6-trinitrophenol in water by the frequently neglected double-logarithmic Stern–Volmer equation.
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15

Yang, Yu, and Edward P. C. Lai. "Optimization of Molecularly Imprinted Polymer Method for Rapid Screening of 17β-Estradiol in Water by Fluorescence Quenching." International Journal of Analytical Chemistry 2011 (2011): 1–8. http://dx.doi.org/10.1155/2011/214747.

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A new method was optimized for rapid screening of 17β-estradiol (E2) in water under 10 min. Molecularly imprinted polymer (MIP) particles (325 ± 25 nm) were added in a water sample at pH 5.5 and 20∘C to form a suspension. Fluorescence emission from E2 nonspecifically bound onto the MIP particles was first quenched by large gold nanoparticles (43 ± 5 nm). The Stern-Volmer plot was linear, with dynamic quenching constants (Ksv) of 2.9 ×104 M-1. Fluorescence emission from E2 specifically bound inside the MIP particles was next quenched by small nitrite anions that easily penetrated the imprinted cavities. The Stern-Volmer plot became nonlinear, withKsv= 2.1 × 102 M-1and static quenching constant (V) below 1.0 M-1. The difference between these two emission intensities varied as the initial E2 concentration in water, generating a Scatchard calibration curve withR2>0.97from 0.1 to 10 ppb.
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16

Yekta, Ahmad, Zahra Masoumi, and Mitchell A. Winnik. "Luminescence measurements of oxygen permeation and oxygen diffusion in thin polymer films." Canadian Journal of Chemistry 73, no. 11 (November 1, 1995): 2021–29. http://dx.doi.org/10.1139/v95-250.

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A new method is developed for analyzing the diffusion of oxygen in thin polymer films via fluorescence quenching measurements. We begin by reviewing previous methods, all of which involve approximations, for the measurement of permeability and diffusion coefficient by luminescence quenching; their shortcomings are clarified. An exact analytic theory is developed that successfully couples Fick's laws of diffusion to the Stern–Volmer equation of intensity quenching. Various modes of experimentation with polymeric films are considered. The equations we derive make the unexpected prediction that the rate of emission intensity decay when O2 diffuses into a polymer film is much faster than the rate of emission intensity enhancement when O2 diffuses out of the same film, even when the molecular diffusivity remains unchanged. Experiments show that this is indeed the observed behaviour. Keywords: diffusion coefficient, oxygen permeability, polymers, quenching, luminescence quenching, Fick's laws. Stern–Volmer equation.
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17

Janosi, Tibor Zoltan, Jouko Korppi-Tommola, Zsolt Csok, Laszlo Kollar, Pasi Myllyperkio, and Janos Erostyak. "Anthracene Fluorescence Quenching by a Tetrakis (Ketocarboxamide) Cavitand." Journal of Spectroscopy 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/708739.

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Quenching of both fluorescence lifetime and fluorescence intensity of anthracene was investigated in the presence of a newly derived tetrakis (ketocarboxamide) cavitand at various concentrations. Time-correlated single photon counting method was applied for the lifetime measurements. A clear correlation between the fluorescence lifetime of anthracene as a function of cavitand concentration in dimethylformamide solution was observed. The bimolecular collisional quenching constant was derived from the decrease of lifetime. Fluorescence intensity was measured in the emission wavelength region around 400 nm as a result of excitation at 280 nm. Effective quenching was observed in the presence of the cavitand. The obtained Stern-Volmer plot displayed upward curvature. The results did not follow even extended Stern-Volmer behavior, often used to describe deviations from static bimolecular quenching. To explain our results we adopted the Smoluchowski model and obtained a reasonable estimate for the molecular radius of the cavitand in solution.
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18

Zhang, Haoran, Bingfu Lei, Hanwu Dong, Yingliang Liu, Mingtao Zheng, and Yong Xiao. "Temperature and Oxygen Sensing Properties of Ru(II) Covalently-Grafted Sol–Gel Derived Ormosil Hybrid Materials." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 4023–28. http://dx.doi.org/10.1166/jnn.2016.11887.

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In this article, oxygen and temperature-sensing hybrid materials consisting of [Ru(Phen)3]2+ portions covalently-grafted onto the sol–gel derived ormosil network were prepared by co-condensation of tetraethoxysilane (TEOS) using n-octyltriethoxysilane as the network modifier. For comparison purposes, the hybrid materials in which [Ru(Phen)3]2+ were conventionally physically-incorporated into the matrix were also prepared. The obtained hybrid materials were characterized by Fourier transform infrared (FT-IR), luminescence intensity oxygen quenching Stern-Volmer plots, temperature quenching plots and excited-state lifetime. The near linear Stern-Volmer plots can be attributed to the approximate heterogeneous environment of the luminophore within the ormosil materials. The results reveal that the covalently-grafted sample is more sensitive to O2, and has a higher sensing sensitivity and a higher thermal activation energy compared to the physically-incorporated one, since these Ru(II) molecules are strongly covalently-grafted onto the Si–O network via the CH2–Si bonds and less –OH group.
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19

Ayoub, Muhammad Haris, Shehryar Ahmad, Zia Ul Hassan, Asad Muhammad Khan, Muhammad Bilal, Amir Waseem, and Ahson Jabbar Shaikh. "Understanding non-covalent interactions of graphene oxide toward transition metal surfaces and relation of binding constants with titration end points from dynamic light scattering studies." Journal of Applied Physics 133, no. 2 (January 14, 2023): 025303. http://dx.doi.org/10.1063/5.0134267.

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The understanding of non-covalent binding interactions of graphene oxide toward transition metal surfaces (Fe, Co, Ni, and Cu) was observed by ultraviolet–visible absorption spectroscopy, fluorescence emission spectroscopy, hydrodynamic size, and zeta potential studies through titration experiments. These interactions mainly occur through C=C double bonds of graphene oxide. Iron and cobalt nanoparticles interact strongly as compared to nickel and copper nanoparticles. The obtained Stern–Volmer plots are curved indicating that static and dynamic quenching occur simultaneously in these systems. The curves obtained for size titration graphs indicated the saturation end point for these titrations, which were then compared with binding constants obtained from linear Stern–Volmer plots. Interestingly, with lower binding constants, a higher concentration of nanoparticles was required for titration end points. These two complimentary techniques stood well quantitatively toward each other. Upon titrating the nanoparticles with graphene oxide, the zeta potential always lowered close to the value of graphene oxide, indicating that hybrids are more stable than the nanoparticles.
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20

Wei, Jun, Dongyan Gu, Shengdan Wang, Jinbo Hu, Xiaowu Dong, and Rong Sheng. "Visible-light-mediated radical arylthiodifluoromethylation of isocyanides with fluorinated 2-pyridyl sulfones." Organic Chemistry Frontiers 5, no. 17 (2018): 2568–72. http://dx.doi.org/10.1039/c8qo00644j.

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2-PySO2CF2SAr were developed as powerful arylthiodifluoromethylation reagents, and the Stern–Volmer luminescence studies demonstrated that the mechanism might operate via a photoredox cycle consisting of a reductive quenching with Na2CO3.
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21

Patil, Shivaram N., F. M. Sanningannavar, B. S. Navati, D. Nagaraja, N. R. Patil, and R. M. Melavanki. "Quenching mechanism of 5BDTC by aniline using Stern–Volmer plots." Canadian Journal of Physics 93, no. 10 (October 2015): 1076–81. http://dx.doi.org/10.1139/cjp-2014-0613.

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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.
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22

Htun, Than. "A Negative Deviation from Stern–Volmer Equation in Fluorescence Quenching." Journal of Fluorescence 14, no. 2 (March 2004): 217–22. http://dx.doi.org/10.1023/b:jofl.0000016294.96775.fd.

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23

Hwang, Yu Lien, and Kuo Chu Hwang. "Nonlinear Stern-Volmer Fluorescence Quenching of Pyrene by C60/70." Fullerene Science and Technology 7, no. 3 (May 1999): 437–54. http://dx.doi.org/10.1080/10641229909350293.

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24

Fedorenko, S. G., and A. I. Burshtein. "Deviations from linear Stern–Volmer law in hopping quenching theory." Journal of Chemical Physics 97, no. 11 (December 1992): 8223–32. http://dx.doi.org/10.1063/1.463445.

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25

Cao, Li, Parambath Anilkumar, Xin Wang, Jia-Hui Liu, Sushant Sahu, Mohammed J. Meziani, Ethan Myers, and Ya-Ping Sun. "Reverse Stern–Volmer behavior for luminescence quenching in carbon nanoparticles." Canadian Journal of Chemistry 89, no. 2 (February 2011): 104–9. http://dx.doi.org/10.1139/v10-096.

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Photoluminescence properties of carbon nanoparticles from different treatments in various suspensions were evaluated, and the results were in general agreement with those available in the literature. An interesting observation was that the quenching of luminescence emissions in the aqueous suspended carbon nanoparticles by aliphatic amines deviated from the classical Stern–Volmer behavior in a somewhat unusual fashion, exhibiting reversed quenching (increasing luminescence intensities) at very low quencher concentrations. The implication of the observation to the mechanistic framework that may account for photoluminescence emissions in both functionalized and naked carbon nanoparticles is proposed and discussed.
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26

Hasegawa, Tadashi, Ayumi Matsuhisa, and Michikazu Yoshioka. "Stern-Volmer quenching kinetics for use of a dualistic quencher." Journal of Physical Organic Chemistry 6, no. 3 (March 1993): 160–62. http://dx.doi.org/10.1002/poc.610060306.

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27

Christov, Christo, Dimitar Ianev, Alexandra Shosheva, and Boris Atanasov. "pH-Dependent Quenching of the Fluorescence of Tryptophan Residues in Class A β-Lactamase from E. coli (TEM-1)." Zeitschrift für Naturforschung C 59, no. 11-12 (December 1, 2004): 824–27. http://dx.doi.org/10.1515/znc-2004-11-1210.

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We performed an investigation of the pH-dependent quenching of the fluorescence of tryptophan residues of TEM-1 β-lactamase from E. coli by uncharged and charged quenchers. pH-dependent Stern-Volmer constants (KSV/pH) of tryptophan residues allowed us to determine subtle but discrete structurally and functionally important processes.
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28

Deepa, H. R., H. M. Suresh Kumar, M. Basanagouda, and J. Thipperudrappa. "Influence of silver nanoparticles on absorption and fluorescence properties of laser dyes." Canadian Journal of Physics 92, no. 2 (February 2014): 163–67. http://dx.doi.org/10.1139/cjp-2013-0133.

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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.
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29

Siegel, Rachel, and Samantha Glazier. "TNT Sensor: Stern–Volmer Analysis of Luminescence Quenching of Ruthenium Bipyridine." Journal of Chemical Education 98, no. 8 (July 19, 2021): 2643–48. http://dx.doi.org/10.1021/acs.jchemed.0c01221.

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30

Torre, Angel de la, Santiago Medina-Rodríguez, Jose C. Segura, and Jorge F. Fernández-Sánchez. "A Polynomial-Exponent Model for Calibrating the Frequency Response of Photoluminescence-Based Sensors." Sensors 20, no. 16 (August 18, 2020): 4635. http://dx.doi.org/10.3390/s20164635.

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In this work, we propose a new model describing the relationship between the analyte concentration and the instrument response in photoluminescence sensors excited with modulated light sources. The concentration is modeled as a polynomial function of the analytical signal corrected with an exponent, and therefore the model is referred to as a polynomial-exponent (PE) model. The proposed approach is motivated by the limitations of the classical models for describing the frequency response of the luminescence sensors excited with a modulated light source, and can be considered as an extension of the Stern–Volmer model. We compare the calibration provided by the proposed PE-model with that provided by the classical Stern–Volmer, Lehrer, and Demas models. Compared with the classical models, for a similar complexity (i.e., with the same number of parameters to be fitted), the PE-model improves the trade-off between the accuracy and the complexity. The utility of the proposed model is supported with experiments involving two oxygen-sensitive photoluminescence sensors in instruments based on sinusoidally modulated light sources, using four different analytical signals (phase-shift, amplitude, and the corresponding lifetimes estimated from them).
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31

Fayed, Tarek A., Gunter Grampp, and Stephan Landgraf. "Fluorescence quenching of aromatic hydrocarbons by nitroxide radicals: a mechanismatic study." International Journal of Photoenergy 1, no. 3 (1999): 173–76. http://dx.doi.org/10.1155/s1110662x99000306.

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The fluorescence quenching of phenanthrene (Phen), 9-cyanophenanthrene (CPhen), 9-cyanoanthracene (CA), perylene (Per), 9,10-dicyanoanthracene (DCA), and 9,10-diphenylanthracene (DPA) using stable nitroxide radicals as quenchers has been studied by steady state and flash photolysis measurements. Both linearity and deviation from linearity in the Stern-Volmer plots have been observed. The active sphere model was used to discuss the upward curvature of the Stern-Volmer plots in case of Per, DCA, and DPA. The bimolecular quenching rate constant(kq)of Phen, CPhen and CA was found to be diffusion controlled while in other cases it is lower than the diffusion limit. On the basis of flash photolysis measurements as well as the overlap between the emission spectra of hydrocarbons and the absorption spectra of radicals, a resonance energy transfer mechanism is taken place in case of Per, DPA, DCA, and CA. For Phen and CPhen where the energy gap between the first excited singlet and the nearest lower triplet state is small, an induced intersystem crossing was suggested. Finally, the quenching process was discussed in terms of the free energy dependence(ΔG)of the electron transfer from nitroxide radicals to the excited hydrocarbons.
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32

Dezhampanah, Hamid, Abdol-Khalegh Bordbar, and Yadolahe Khodadusdt. "Spectroscopic Studies on the Interaction of a Water-Soluble Cationic Porphyrin with Bovine Serum Albumin." Analytical Cellular Pathology 36, no. 1-2 (2013): 21–26. http://dx.doi.org/10.1155/2013/439504.

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The interaction of a water-soluble cationic porphyrin, Cobalt(III) 5, 10, 15, 20-tetrakis (1-methylpyridinium-4-yl) porphyrin [Co(III)TMPyP], with bovine serum albumin (BSA) has been studied in 1 mM phosphate buffer pH 7.0 containing 5 mM NaCl by UV-vis absorption, resonance light scattering (RLS) and fluorescence spectroscopies at 25°C. The results of RLS studies represent no aggregate formation of porphyrin in the surface of BSA and low tendency of this porphyrin for aggregate formation.The binding of porphyrin complex to BSA quenches fluorescence emission of BSA via a dynamic mechanism and the quenching process obeys a linear Stern-Volmer relationship. The values of Stern-Volmer constants, KSV, was determined nearly 105M−1, that depend on BSA concentration. The average aggregation number of BSA calculated from the analysis of fluorescence quenching data indicates that absence of any porphyrin induced aggregation of BSA due to its interaction with porphyrin complex. The binding of Co(III) TMPyP had no obvious effect on the molecular conformation of the protein. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the protein.
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33

Chen, Jingrun, Jason D. A. Lin, and Thuc-Quyen Nguyen. "Towards a Unified Macroscopic Description of Exciton Diffusion in Organic Semiconductors." Communications in Computational Physics 20, no. 3 (August 31, 2016): 754–72. http://dx.doi.org/10.4208/cicp.050615.010216a.

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AbstractWe study the exciton diffusion in organic semiconductors from a macroscopic viewpoint. In a unified way, we conduct the equivalence analysis between Monte-Carlo method and diffusion equation model for photoluminescence quenching and photocurrent spectrum measurements, in both the presence and the absence of Förster energy transfer effect. Connections of these two models to Stern-Volmer method and exciton-exciton annihilation method are also specified for the photoluminescence quenching measurement.
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34

Wiczk, Wiesław M., and Tadeusz Latowski. "Photophysical and Photochemical Studies of Polycyclic Aromatic Hydrocarbons in Solutions Containing Tetrachloromethane II. The Solvent Effect on the Fluorescence Quenching of Aromatic Hydrocarbons by Tetrachloromethane." Zeitschrift für Naturforschung A 42, no. 11 (November 1, 1987): 1290–95. http://dx.doi.org/10.1515/zna-1987-1111.

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Fluorescence quenching of aromatic hydrocarbons in a large concentration range of the quencher has been studied in a variety of two-component mixtures of tetrachloromethane with other solvents. In aliphatic solvents the process could be described by the Stern-Volmer equation, whereas in the remaining mixtures the fluorescence quenching curves showed a parabolic behaviour which has been explained in terms of specific interactions between the components of the mixtures.
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35

Amézqueta, Susana, Anna Bolioli Maria Bolioli, José Luis Beltrán, and Clara Ràfols. "Evaluation of the interactions between human serum albumin (HSA) and warfarin or diflunisal by using molecular fluorescence using two approaches." ADMET and DMPK 6, no. 1 (March 25, 2018): 47. http://dx.doi.org/10.5599/admet.6.1.473.

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<p class="PaperH1">Serum albumin is the main drug transporter of the bloodstream and contains two main binding sites: Sudlow I or acidic drug binding site, and Sudlow II or benzodiazepine binding site. Warfarin, a well-known anticoagulant drug commonly used in the prevention of thrombosis and thromboembolism, binds to Sudlow I site, whereas non-steroidal antiinflammatory drugs (NSAIDs) such as diflunisal bind preferentially to Sudlow II site. Albumin is a fluorophore that modifies its fluorescence (quenching or enhancement effect) when it is bound to a drug. The application of the double logarithm Stern-Volmer equation allows the calculation of the stoichiometry and the binding constant of the process. This procedure does not consider the possible interferences coming from the fluorescence of the drug though. Another strategy to evaluate the binding constants is to consider the whole spectrum, taking into account all the possible species in equilibrium; in this case we have used an extended version of the STAR program, which can deal with 300 spectra, each containing up to 300 data points. The aim of this work is to compare both approaches to evaluate the interaction between warfarin (Sudlow I) and diflunisal (Sudlow II) and HSA: the double logarithm Stern-Volmer equation and the STAR program.</p>
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36

Hamity, M., and R. H. Lema. "The photochemistry of electron donor–acceptor (EDA) complexes in micellar solutions. I. The stilbene–methylviologen system." Canadian Journal of Chemistry 66, no. 7 (July 1, 1988): 1552–57. http://dx.doi.org/10.1139/v88-252.

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The association constants for the electron donor–acceptor (EDA) complexes formed between both cis-stilbene (cS) and trans-stilbene (tS) as donors and methylviologen (MV+2) as acceptor were determined in ethanol and micellar sodium dodecyl sulfate (SDS) solutions in the range of SDS concentration 0.05–0.1 M. The values obtained in micellar solutions were much higher than those in ethanol and were heavily dependent upon SDS concentration. This effect is due to an increase in the local concentration of the reactants in the micellar pseudophase. The tS fluorescence quenching by MV+2 was also studied in the same solvent media. In ethanol, the Stern–Volmer plot was found to be linear, with quenching constant (KSV) similar to the association constant determined by the absorption method. In micellar solutions, although upward curvature of the Stern–Volmer plots was observed, a reaction scheme based on static quenching via ground state EDA complex is proposed, which explains the experimental results. Irradiation in the absorption band of the EDA complexes formed by tS or cS and MV+2 was carried out in ethanol and SDS solutions, in the absence of oxygen. Only cis–trans isomerization of cS in SDS solution was observed, with a quantum yield value of Φcis = 0.012.
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37

Vasseur, M., R. Frangne, and F. Alvarado. "Buffer-dependent pH sensitivity of the fluorescent chloride-indicator dye SPQ." American Journal of Physiology-Cell Physiology 264, no. 1 (January 1, 1993): C27—C31. http://dx.doi.org/10.1152/ajpcell.1993.264.1.c27.

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The fluorescence intensity of 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ) in an N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) 2-(N-morpholino)ethanesulfonic acid (MES)-Tris(hydroxymethyl)aminomethane buffer, pH 7.0, decreased as a function of Cl- concentration and/or gluconate concentration, as expected. Contrary to expectation, however, the fluorescence intensity progressively increased as the pH decreased, independently of the presence of gluconate. Consequently, the modulation of SPQ fluorescence by commonly used buffers was investigated as a function of pH. Titration curves demonstrated SPQ quenching and yielded pK values characteristic of each buffer. from here, pH-independent Stern-Volmer constants, KQbase, were calculated for each of the morpholine derivatives, MES and 3-(N-morpholino)-2-hydroxypropanesulfonic acid. In contrast, HEPES and piperazine-N,N'-bis(2-ethanesulfonic acid), which are piperazine derivatives, exhibited an additional pH-independent "molecular" quenching constant KmQ throughout the pH range 3-10. To study chloride fluxes, therefore, what counts is the apparent Cl-Stern-Volmer constant KappCl, which is a function of both pH and buffer composition. Equations describing these relationships are presented. In conclusion, unless both pH and the buffer composition are taken into account, SPQ is unsuitable for studying the concomitant transmembrane fluxes of Cl- and H+.
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38

Shin, Bomina, and Honglae Sohn. "Heavy Atom Effect on Metallole Nanoaggregates and Their Explosive Sensing Applications." Journal of Nanoscience and Nanotechnology 20, no. 9 (September 1, 2020): 5599–603. http://dx.doi.org/10.1166/jnn.2020.17638.

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Electronic and optical properties of metallole nanoaggregates (M = Ge and Sn) were investigated. Amplified photoluminescence (PL) properties, absolute quantum yields (QY), and critical aggregation concentrations for the metallole nanoaggregates were measured. The an aggregation-induced emission enhancement (AIEE) property decreases as the central atom becomes heavier in the metallole ring. Detection of TNT was achieved by the quenching PL of the metallole nanoaggregates. A linear Stern–Volmer relationship was observed for the detection of TNT.
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39

Kou, Meng, Feng Qin, Weiming Lv, Xiyu Zhang, Yongda Wang, Hua Zhao, and Zhiguo Zhang. "Oxygen-Varying Correlated Fluorescence for Determining the Stern–Volmer Constant of Porphyrin." Journal of Physical Chemistry Letters 13, no. 8 (February 23, 2022): 2007–11. http://dx.doi.org/10.1021/acs.jpclett.2c00125.

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40

Bouchy, M., F. Baros, and J. C. Andre. "Mean configurational distribution function for the steady state and stern-volmer representation." Reaction Kinetics and Catalysis Letters 32, no. 2 (September 1986): 331–39. http://dx.doi.org/10.1007/bf02068332.

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41

Payne, Sarah J., J. N. Demas, and B. A. DeGraff. "Abnormal Behavior in Stern—Volmer Luminescence Quenching Measurements via Apparent Lifetime Methods." Applied Spectroscopy 63, no. 4 (April 2009): 437–41. http://dx.doi.org/10.1366/000370209787944307.

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42

Tomin, V. I. "Determination of the stern-volmer constant in quantum systems with dual fluorescence." Optics and Spectroscopy 105, no. 2 (August 2008): 223–27. http://dx.doi.org/10.1134/s0030400x08080109.

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43

Launikonis, A., PA Lay, AWH Mau, AM Sargeson, and WHF Sasse. "Light-Induced Electron-Transfer Reactions Involving the Tris(2,2'-Bipyridine)Ruthenium Dication and Related Complexes. 3. Improved Synthesis of 2,2'-Bipyridine-4,4'-Dicarboxylic Acid and Photoreduction of Water by Bis(2,2'-Bipyridine)(2,2'-Bipyridine-4,4'-Dicarboxylic Acid)Ruthenium(II)." Australian Journal of Chemistry 39, no. 7 (1986): 1053. http://dx.doi.org/10.1071/ch9861053.

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The oxidation of 4,4′-dimethyl-2,2′-bipyridine with potassium permanganate in water gives 2,2′-bipyridine-4,4′-dicarboxylic acid and 4′-methyl-2,2?-bipyridine-4-carboxylic acid. The latter acid is oxidized to the diacid by boiling nitric acid. Complexes of the type Ru ( bpy )2L2+ have been prepared where L is 2,2′-bipyridine-4,4′- dicarboxylic acid, diethyl 2,2′-bipyridine-4,4′-dicarboxylate, 4′- methyl-2,2′-bipyridine-4-carboxylic acid and ethyl 4′-methyl-2,2′- bipyridine-4-carboxylate. These complexes have been compared with [ Ru ( bpy )3]2+ as sensitizers for the photoreduction of water. Stern- Volmer analysis has been applied to the quenching of their luminescence by methylviologen (mv2+), [Co(sep)]3+ (sep is 1,3,6,8,10,13,16,19- octaazabicyclo [6.6.6] icosane ) and [Co( CLsar )]3+ ( CLsar is 1-chloro- 3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane ). Changes in the Stern-Volmer constants have been related to the free energy changes associated with the oxidative quenching and the overall charges of the ruthenium complexes. The rates of formation of hydrogen compared favourably in sacrificial cycles with the ruthenium complexes as sensitizers, mv2+, Co(sep)3+ as electron-transfer agents, platinum/poly(vinyl alcohol) as catalyst, and ethylenediaminetetraacetic acid as electron donor. The results obtained have been discussed in terms of variations in the efficiencies of cage escape in the oxidative quenching and competition between electron transfer and energy transfer.
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44

Igoshin, O. A., and A. I. Burshtein. "Impurity quenching of fluorescence in intense light. Violation of the Stern–Volmer law." Journal of Chemical Physics 112, no. 24 (June 22, 2000): 10930–40. http://dx.doi.org/10.1063/1.481732.

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45

Tasic, Uros S., Ernest R. Davidson, and Charles S. Parmenter. "Non-Stern−Volmer Quenching of S1pDFB Fluorescence by O2and the Charge Transfer Complex†." Journal of Physical Chemistry A 107, no. 18 (May 2003): 3552–58. http://dx.doi.org/10.1021/jp022281y.

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46

Melavanki, R. M., R. A. Kusanur, J. S. Kadadevaramath, and M. V. Kulakarni. "Quenching mechanisms of 5BAMC by aniline in different solvents using Stern–Volmer plots." Journal of Luminescence 129, no. 11 (November 2009): 1298–303. http://dx.doi.org/10.1016/j.jlumin.2009.06.011.

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47

Pan, Bo, Baoshan Xing, Wenxin Liu, Guanhua Xing, and Shu Tao. "Investigating interactions of phenanthrene with dissolved organic matter: Limitations of Stern–Volmer plot." Chemosphere 69, no. 10 (November 2007): 1555–62. http://dx.doi.org/10.1016/j.chemosphere.2007.05.059.

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48

Zeng, Hualing, and Gilles Durocher. "Analysis of fluorescence quenching in some antioxidants from non-linear Stern—Volmer plots." Journal of Luminescence 63, no. 1-2 (January 1995): 75–84. http://dx.doi.org/10.1016/0022-2313(94)00045-e.

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49

Boguta, Patrycja, and Zofia Sokołowska. "Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes." Molecules 25, no. 6 (March 12, 2020): 1297. http://dx.doi.org/10.3390/molecules25061297.

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The aim of the study was defined as a complementary analysis of molecular interactions between zinc (Zn) and fulvic acids (FAs) at a broad pH range (3–7), different metal concentrations (0–50 mg dm−3) and chemical properties of FAs and their impact on the Zn binding mechanism, stability, and efficiency. The results showed that the complexation reaction prevailed at pH 6 and 7, whereas protons exchange dominated interactions at pH 3. Stability constant of the complexes increased along with pH (logK increased from ~3.8 to 4.2). Complexation was preferred by less-humidified structures of lower molecular mass containing more oxygen groups. The number of fluorophores available for Zn(II) increased from pH 3 to 7 by ~44%. Depending on the pH, complexation involved a bidentate chelate, monodentate and bidentate bridging mode. Zn(II) binding was insufficiently modeled by the classic Stern–Volmer equation and well described by the double logarithmic equation (R > 0.94) as well as by a modified Stern–Volmer formula assuming the existence of available and unavailable fluorophore populations (R > 0.98). The fluorescence ratio of different fluorophores was proposed as an indicator of the binding affinity of various structures. A positive relationship was found between the fraction of accessible fluorophores and Zn(II) binding at pH 7 determined based on proton release (R = 0.91–0.97). The obtained results can find application in controlling the mobility and bioavailability of Zn in different conditions.
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50

Manjushree, M., and Hosakere D. Revanasiddappa. "A Diversified Spectrometric and Molecular Docking Technique to Biophysical Study of Interaction between Bovine Serum Albumin and Sodium Salt of Risedronic Acid, a Bisphosphonate for Skeletal Disorders." Bioinorganic Chemistry and Applications 2018 (June 28, 2018): 1–13. http://dx.doi.org/10.1155/2018/6954951.

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The binding interaction between bovine serum albumin (BSA) and sodium salt of risedronic acid (RSN) was studied by using the FT-IR (Fourier transform infrared), UV-Vis (ultraviolet–visible), fluorescence (emission and synchronous), CD (circular dichroism) spectrometric, and computational (molecular docking) techniques at 289, 297, and 305 K temperatures with physiological buffer of pH 7.40. The conformational and secondary structural changes observed for BSA from CD spectra and by curve fitting procedure were applied to Fourier self-deconvolution in FT-IR spectra. The formation of a BSA-RSN complex was confirmed from UV-Vis spectroscopy. The static type of quenching shown for RSN to BSA was verified from Stern–Volmer and modified Stern–Volmer equations. The binding constant of order 105 was obtained to be confirming that there exists a strong binding interaction between BSA and RSN. Synchronous fluorescence shows that the microenvironment of tryptophan was altered, not tyrosine of BSA; in addition to this, the distance between tryptophan of BSA and RSN was found out from Forster’s theory of nonradiation energy transfer. The interaction between BSA and RSN mainly occurred as a result of hydrogen bonds and van der Waals forces, the process is exothermic and spontaneous, and it was achieved through van ’t Hoff equation. This interaction was affected by the presence of biologically active Fe2+, Ni2+, Ca2+, Mg2+, and Cd2+ ions and was also studied. The subdomain IIIA of BSA involved with RSN interaction was authenticated from molecular docking analysis.
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