Journal articles: 'Stern-Volmer Plot'

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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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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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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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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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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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6

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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Ciotta, E., P. Prosposito, and R. Pizzoferrato. "Positive curvature in Stern-Volmer plot described by a generalized model for static quenching." Journal of Luminescence 206 (February 2019): 518–22. http://dx.doi.org/10.1016/j.jlumin.2018.10.106.

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Sidarai, Ashok H., Vani R. Desai, Shirajahammad M. Hunagund, Mahantesha Basanagouda, and Jagadish S. Kadadevarmath. "Fluorescence Quenching of DMB by Aniline in Benzene-Acetonitrile Mixture." International Letters of Chemistry, Physics and Astronomy 65 (April 2016): 32–36. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.65.32.

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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.

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9

Thanikaivalan, E., and R. Jothilakshmi. "Quenching of Silver Nanoparticles." Materials Science Forum 781 (March 2014): 135–44. http://dx.doi.org/10.4028/www.scientific.net/msf.781.135.

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Silver nanoparticles of different sizes have been prepared. Absorption spectroscopy reveals the formation of ground state complex. Fluorescence spectroscopy has been used to study the signatures of fluorescence quenching. Properties of N-(2-methylthiophenyl)-2-hydroxy-1-naphthaldimine (NMTHN) on silver nanoparticles has been investigated using optical absorption and fluorescence emission techniques. Quenching of fluorescence of N-(2-methylthiophenyl)-2-hydroxy-1-naphthaldimine has been found to decrease with increase in the size of the silver nanoparticles. The results of the quenching experiments were analyzed through Stern Volmer plot.

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AMAO, YUTAKA, KEISUKE ASAI, and ICHIRO OKURA. "Oxygen sensing based on lifetime of photoexcited triplet state of platinum porphyrin-polystyrene film using time-resolved spectroscopy." Journal of Porphyrins and Phthalocyanines 04, no. 03 (April 2000): 292–99. http://dx.doi.org/10.1002/(sici)1099-1409(200004/05)4:3<292::aid-jpp216>3.0.co;2-w.

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Optical oxygen-sensing systems based on the quenching of the photoexcited triplet state of platinum porphyrins—platinum octaethylporphyrin (PtOEP) and platinum tetrakis(pentafluorophenyl)porphyrin (PtTFPP)—in polystyrene (PS) using two different time-resolved spectroscopies (luminescence lifetime measurement and diffuse reflectance laser flash photolysis) have been developed. Using both spectroscopies, the same values of Stern-Volmer constant KSV and quenching rate constant kq (KSV = kqτ0) are obtained. The decays of the luminescence and triplet-triplet reflectance of the platinum porphyrins in PS consisted of two components (faster and slower lifetimes) in the absence and presence of oxygen. For both faster and slower components the lifetime decreases with increasing oxygen concentration. For both components a Stern-Volmer plot of the platinum porphyrin-PS films exhibits linearity. However, kq of the faster component is larger than that of the slower component (for PtOEP, three times larger; for PtTFPP, 40 times larger), indicating that two different oxygen-accessible sites exist in the platinum porphyrin-PS films. The faster and slower components are related to oxygen-accessible sites on the surface and in the bulk of the platinum porphyrin films respectively. Concerning the fractional contributions of each lifetime component, the contribution of the faster component is greater than that of the slower component, indicating that the sensing site on the surface is important for optical sensing. The contribution of different oxygen-accessible sites in platinum porphyrin-PS films for oxygen sensing is clarified by these techniques.

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11

J, Thipperudrappa. "Study of Role of Silver Nanoparticles on Spectroscopic Properties of a KetocyanineDye." Mapana - Journal of Sciences 15, no. 1 (July 1, 2016): 1–16. http://dx.doi.org/10.12723/mjs.36.1.

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The role of silver nanoparticles on spectroscopic properties of the ketocyaninedye 2,5-di[(E)-1-(4- dimethylaminophenyl) methylidine]-1-cyclopentanone (2,5-DMAPMC) has been investigated using absorption and fluorescence spectroscopy. Silver nanoparticles are synthesized by chemical reduction method and estimated size from SEM measurements is 22 nm. The changes in absorption spectrum of dye in the presence of silver nanoparticles suggest the possible interaction with silver nanoparticles. The Stern-Volmer plot of fluorescence quenching is found to be nonlinear showing positive deviation. The magnitude of quenching rate parameter and fluorescence lifetime measurements indicates the presence of both collisional and static quenching mechanisms. The binding constant and number of binding sites for static part of the quenching have been

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Baruah, Upama, Neelam Gogoi, Achyut Konwar, Manash Jyoti Deka, Devasish Chowdhury, and Gitanjali Majumdar. "Carbon Dot Based Sensing of Dopamine and Ascorbic Acid." Journal of Nanoparticles 2014 (December 29, 2014): 1–8. http://dx.doi.org/10.1155/2014/178518.

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We demonstrate carbon dot based sensor of catecholamine, namely, dopamine and ascorbic acid. Carbon dots (CDs) were prepared from a green source: commercially available Assam tea. The carbon dots prepared from tea had particle sizes of ∼0.8 nm and are fluorescent. Fluorescence of the carbon dots was found to be quenched in the presence of dopamine and ascorbic acid with greater sensitivity for dopamine. The minimum detectable limits were determined to be 33 μM and 98 μM for dopamine and ascorbic acid, respectively. The quenching constants determined from Stern-Volmer plot were determined to be 5 × 10−4 and 1 × 10−4 for dopamine and ascorbic acid, respectively. A probable mechanism of quenching has been discussed in the paper.

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13

Martins, Cátia D. F., M. Manuela M. Raposo, and Susana P. G. Costa. "Intermolecular Quenching of Edans/Dabcyl Donor–Acceptor FRET Pair." Proceedings 41, no. 1 (November 14, 2019): 34. http://dx.doi.org/10.3390/ecsoc-23-06613.

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The intermolecular quenching between 5-(2′-aminoethyl)aminonaphthalene sulfonic acid (Edans) and 4-[[4′-(N,N-dimethylamino)phenyl]diazenyl]benzoic acid (Dabcyl) was studied by photometric and fluorimetric measurements at pH 7.5 in phosphate buffer. The spectral properties of the Edans/Dabcyl donor–acceptor pair were determined and Dabcyl exhibited an intense absorption band at 463 nm, contributing to the quenching efficiency. We also found the primary requirement for fluorescence resonance energy transfer (FRET), the excellent overlap between the fluorescence emission spectrum of the donor molecule and the absorption spectrum of the acceptor molecule, resulting in efficient energy transfer. The quenching mechanism was studied using the Stern–Volmer plot, confirming that this FRET pair was involved in a dynamic quenching process.

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14

Yuan, Yan-xia, Hong-shang Peng, Jian-tao Ping, Xiao-hui Wang, and Fang-tian You. "A Pyrene@Micelle Sensor for Fluorescent Oxygen Sensing." BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/245031.

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For most fluorescent oxygen sensors developed today, their fabrication process is either time-consuming or needs specialized knowledge. In this work, a robust fluorescent oxygen sensor is facilely constructed by dissolving pyrene molecules into CTAB aqueous solution. The as-prepared pyrene@micelle sensors have submicron-sized diameter, and the concentration of utilized pyrene can be reduced as low as 0.8 mM but still can exhibit dominant excimer emission. The excimer fluorescence is sensitive to dissolved oxygen in both intensity and lifetime, and the respective Stern-Volmer plot follows a nonlinear behavior justified by a two-site model. Because of the merits of large Stokes shift (~140 nm), easy fabrication, and robustness, the pyrene@micelle sensors are very attractive for practical determination of oxygen.

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15

Deslauriers, Hélène, Sylvain Dufour, and Guy J. Collin. "La photochimie de l'isoprène gazeux dans la région de l'ultraviolet très lointain." Canadian Journal of Chemistry 66, no. 6 (June 1, 1988): 1513–19. http://dx.doi.org/10.1139/v88-244.

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Yields of various products have been measured in the photolysis of isoprene at 184.9, 213.8, and 228.8 nm and at pressures between 1 and 400 Torr. At each wavelength, the major process is the rupture of a C—CH3 bond, which leads to the formation of methyl and CH2=C=CHCH2. The quantum yield for this process is 0.83 ± 0.08 at 213.8 nm. The lifetime of the intermediate involved in this process is 20 ns at 184.9 nm. Similar quantities of ethylene and C3H4[Formula: see text] and propene and acetylene [Formula: see text] are measured. All the measured yields decrease with an increase in the pressure. In addition to these fragmentation processes, isomerization reactions are also observed, particularly at 228.8 nm. They lead to the formation of 1,3- and 1,4-pentadiene as well as 3-methyl-1,2-butadiene. The Stern–Volmer plot for each isomer is different and each plot shows a strong negative curvature, indicating the complexity of the reaction process. The lifetime of each intermediate is 2 ns or less.

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Fraiji, Elie K., Timothy R. Cregan, and T. C. Werner. "Binding of 2-Acetylnaphthalene to Cyclodextrins Studied by Fluorescence Quenching." Applied Spectroscopy 48, no. 1 (January 1994): 79–84. http://dx.doi.org/10.1366/0003702944027624.

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The molecule 2-acetylnaphthalene (2-AN) exhibits significant room-temperature fluorescence only in strong hydrogen-bonding solvents, such as water and fluorinated alcohols. As a consequence, the fluorescence of 2-AN is strongly quenched when it binds in the relatively nonpolar cavity of cyclodextrins (CDs). Fluorescence lifetime data confirm that the quenching is static rather than dynamic, and thus the slope of the Stern-Volmer quenching plot (F°/F vs . [CD]) is equal to K, the binding constant. We have used these plots to measure K for 1:1 complexes formed between 2-AN and several CDs, including unsubstituted α;-, β-, and γ-CD and a dimethyl substituted β-CD. In addition, we have determined Δ H° and Δ S° of binding from the temperature dependence of these plots. The room-temperature binding constants vary over a 50-fold range for the 2-AN:CD complexes studied herein, and the variability stems primarily from the Δ S° term. We report here the results of this work and also show evidence for observations other than 1:1 complexes, including emission from the excimer of 2-AN in the presence of γ-CD.

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17

Gehlen, Marcelo H. "The centenary of the Stern-Volmer equation of fluorescence quenching: From the single line plot to the SV quenching map." Journal of Photochemistry and Photobiology C: Photochemistry Reviews 42 (March 2020): 100338. http://dx.doi.org/10.1016/j.jphotochemrev.2019.100338.

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18

Chatterjee, Poonam Mishra, Deepika Pandey Tiwari, Silpi Datta, Suman Chakrabarty, Ritu Raval, and Ashok Kumar Dubey. "Probing into Methylene Blue Interaction with Polyglutamic Acid: Spectroscopic and Molecular Dynamics Simulation Studies." Asian Journal of Chemistry 31, no. 9 (July 31, 2019): 1949–58. http://dx.doi.org/10.14233/ajchem.2019.22100.

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Polyglutamic acid (PGA) is an anionic biopolymer which is stained with methylene blue (MB) in agar or polyacrylamide gels for analysis. Polyglutamic acid identification involves a tedious extraction and analytical process. The molecular association of polyglutamic acid and methylene blue can be used for rapid spectroscopic detection of polyglutamic acid production during fermentation. This triggered the study on investigation of polymer-dye interaction mechanism. Concentration range of polyglutamic acid, 0.001 to 0.06 μM with a fixed methylene blue concentration of 25 μM exhibited significant differences in the spectra. Preferential higher order aggregate formation of methylene blue molecules was substantiated with molecular dynamics simulation results. Fluorescence spectroscopy demonstrated a quenching effect of polyglutamic acid on methylene blue fluorescence until a certain concentration range, beyond which the Stern-Volmer (SV) plot shows a negative deviation. Polyglutamic acid was observed to promote higher order of intramolecular stacking interactions of methylene blue, possibly due to interplay of electrostatic and hydrophobic interactions between polyglutamic acid, methylene blue alone and PGA-MB systems

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19

Kulkarni, Prashant A., Mahendra A. More, Vinod Nandre, and Anupa Kumbhar. "Investigations on sensing of picric acid in aqueous medium via fluorescence quenching of quinine sulfate." Modern Physics Letters B 34, no. 07n09 (March 19, 2020): 2040040. http://dx.doi.org/10.1142/s0217984920400400.

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This research describes systematic investigations on sensing of high explosives such as picric acid (PA), RDX, NTO, and trinitrotoluene (TNT) in aqueous medium via fluorescence quenching of quinine sulfate (QS). Although all the explosives exhibit fluorescence quenching of QS, highest response is observed for PA. Fluorescence quenching of [Formula: see text][Formula: see text]50% (in contrast to pristine QS) at [Formula: see text][Formula: see text]390 nm is observed for 10 nm (2.29 [Formula: see text]g of PA dissolved in 20 [Formula: see text]l of distilled water). The analysis of the Stern–Volmer (SV) plot implies dominance of static quenching mechanism in comparison to dynamic quenching mechanism. Furthermore, the effect of operational temperature on fluoresce quenching response for PA has been investigated, and values of enthalpy, entropy, and Gibbs free energy of interaction at various temperatures are estimated. The temperature-dependent studies reveal that fluorescence quenching is due to formation of strong hydrogen bonds, complemented by computational analysis.

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Okazaki, Masaharu, Yutaka Tai, Keichi Nunome, and Kazumi Toriyama. "Excimer formation of pyrene as a probe to investigate the recombination of geminate pairs: effect of multicomponent recombination on Stern-Volmer plot." Chemical Physics Letters 171, no. 5-6 (August 1990): 537–41. http://dx.doi.org/10.1016/0009-2614(90)85259-f.

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21

Melavanki, R. M., N. R. Patil, D. Nagaraja, H. D. Patil, J. S. Kadadevarmath, and R. A. Kusanur. "Solvent Effect on Fluorescence Quenching of 7, 8 Benzo‑4‑azido Methyl Coumarin by Aniline." Mapana - Journal of Sciences 12, no. 1 (February 7, 2013): 69–85. http://dx.doi.org/10.12723/mjs.24.7.

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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.

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Verma, Awadhesh Kumar, and Z. A. Ansari. "Fluorescent ZnO Quantum Dot Probe to Study Glucose–Glucose Oxidase Interaction via Fluorescence Resonance Energy Transfer." Sensor Letters 18, no. 5 (May 1, 2020): 351–65. http://dx.doi.org/10.1166/sl.2020.4232.

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In this work, emphasis is to utilize FRET method to analyze GOx and glucose interaction using fluorescent ZnO QDs as the probes. Fluorescent ZnO and ZnOext QDs were synthesized using sol– gel technique and green synthesis method as donor and acceptor nanoprobes. Structural, optical and morphological characterization of QDS were carried out using UV-visible absorption, fluorescence, FTIR, XRD and field emission scanning electron microscopy. Band gap estimated from Tauc plot is 3.49 and 3.35 eV for ZnO and ZnOext QDs and XRD reveal Wurtzite structure of grown crystals. Systematic absorption study for ZnO–GOx and ZnOext–GOx reveal association constant of –8.3361 M–1 and –2.57646 M –1 for ZnO and ZnOext using Benesi-Hildebrand plot. The binding constant obtained from Stern-Volmer equation is 1.0466 μM –1 and 1.97 μM –1 for ZnO/ZnOext–GOx conjugate and suggest static quenching in the system. CD spectroscopy reveal native state of protein in conjugate sytem. Constant Förster radius (Ro) in ZnOext–GOx system suggest the average 〈κ2〉 as 2/3 and is independent of donor–acceptor distance as normally assumed in FRET system varies from ∼4.5% in ZnO–GOx and ∼5% in ZnOext–GOx system. It indicate better energy transferrin earlier system than formal. The physiological range of glucose from 60 mg–440 mg/dl using this technique in which ZnOext–GOx as donor probe exhibit better response towards glucose than ZnO–GOx system and correlated to the presence of phyotochemicals on the QD surface.

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Raj, Vidya, and Sreenivasan Kunnetheeri. "Nonconjugated Polyelectrolyte as Efficient Fluorescence Quencher and Their Applications as Biosensors: Polymer-Polymer Interaction." ISRN Analytical Chemistry 2014 (January 22, 2014): 1–8. http://dx.doi.org/10.1155/2014/841857.

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A simple fluorescence quenching method for the quantitation in serum of an acute phase reactant, C-reactive protein (CRP), which can differentiate between viral and bacterial infections, is described, where material and reagent costs are minimal. The study harnesses a fluorescence quenching between a nonfluorescent polyelectrolyte containing a ligand (O-phosphorylethanolamine, PEA) and fluorophore (fluorescamine isomer 1) containing polyelectrolyte. The quenching was attributed due to strong polymer-polymer interaction through intermolecular hydrogen bonding. The nonlinear behaviour of Stern-Volmer plot indicates a binding induced quenching, that is, static quenching. However, fluorescence was found to increase in presence of C-reactive protein, due to the specific molecular recognition occurring between CRP and PEA, thereby excluding fluorophore containing chain. A definite correlation was found between concentration of CRP and fluorescence intensity and the method exhibited a linear relationship in the range of 40–360 ng/mL with a detection limit of 30 ± 2 ng/mL. The antibody free method was successfully applied for the analysis of CRP in human serum samples and the method showed good correlation with hospital measurements (y=1.0313x−0.1423; n=32; R=0.9998, P<0.0001). Thus the fluorescence based polyelectrolyte biosensor is a potential system for rapid, and antibody free platform for CRP detection.

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Kuzmič, Petr, and Milan Souček. "Substituent effects in aromatic photochemistry. UV irradiation of 3,4-dimethoxybenzonitrile and 3,4-dimethoxyacetophenone in the presence of inorganic anions." Collection of Czechoslovak Chemical Communications 52, no. 4 (1987): 980–88. http://dx.doi.org/10.1135/cccc19870980.

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Ultraviolet photolysis of 3,4-dimethoxybenzonitrile (Ia) and 3,4-dimethoxyacetophenone (IIa) in the presence of the hydroxide or cyanide anion leads to nucleophilic displacement of either the para or the meta methoxy substituent. The ratio of isomeric photoproducts is dependent upon the nature of the nucleophile. Photoreactions with the OH- anion lead exclusively to the substitution at C-3. On the other hand, both isomers are formed when acetophenone IIa is irradiated in the presence of CN-, with the C-3/C-4 substitution ratio 3:2. In the case of the photocyanation of Ia, the C-4 substituted product dominates, the C-3/C-4 ratio ranging from 1:2 to 1:6 in dependence on the nucleophile concentration. These differences between the OH- and CN- anions are related to the results of a fluorescence quenching study which has revealed that only the latter nucleophile interacts with singlet-excited substrates. A non-linear Stern-Volmer plot was observed for the quenching of the second excited state of Ia by the cyanide anion. This indicates several distinct quenching modes, in relation to the concentration dependence of regioselectivity. The activating power of –H, -CN, -COCH3, and -NO2 substituents, as measured by relative quantum yields of disappearance for 3,4-dimethoxy-R-substituted benzenes, is 1:2.5:5:580 and 1:1.5:6:1000 in their photoreactions with OH- and CN- anions, respectively.

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Chinnathambi, Shanmugavel, Subramani Karthikeyan, Devadasan Velmurugan, Nobutaka Hanagata, Prakasarao Aruna, and Singaravelu Ganesan. "Investigations on the Interactions of 5-Fluorouracil with Herring Sperm DNA: Steady State/Time Resolved and Molecular Modeling Studies." Biophysical Reviews and Letters 10, no. 02 (June 2015): 115–33. http://dx.doi.org/10.1142/s1793048015500034.

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In the present study, the interaction of 5-Fluorouracil with herring sperm DNA is reported using spectroscopic and molecular modeling techniques. This binding study of 5-FU with hs-DNA is of paramount importance in understanding chemico–biological interactions for drug design, pharmacy and biochemistry without altering the original structure. The challenge of the study was to find the exact binding mode of the drug 5-Fluorouracil with hs-DNA. From the absorption studies, a hyperchromic effect was observed for the herring sperm DNA in the presence of 5-Fluorouracil and a binding constant of 6.153 × 103 M-1 for 5-Fluorouracil reveals the existence of weak interaction between the 5-Fluorouracil and herring sperm DNA. Ethidium bromide loaded herring sperm DNA showed a quenching in the fluorescence intensity after the addition of 5-Fluorouracil. The binding constants for 5-Fluorouracil stranded DNA and competitive bindings of 5-FU interacting with DNA–EB systems were examined by fluorescence spectra. The Stern–Volmer plots and fluorescence lifetime results confirm the static quenching nature of the drug-DNA complex. The binding constant Kb was 2.5 × 104 L mol-1 and the number of binding sites are 1.17. The 5-FU on DNA system was calculated using double logarithmic plot. From the Forster nonradiative energy transfer study it has been found that the distance of 5-FU from DNA was 4.24 nm. In addition to the spectroscopic results, the molecular modeling studies also revealed the major groove binding as well as the partial intercalation mode of binding between the 5-Fluorouracil and herring sperm DNA. The binding energy and major groove binding as -6.04 kcal mol-1 and -6.31 kcal mol-1 were calculated from the modeling studies. All the testimonies manifested that binding modes between 5-Fluorouracil and DNA were evidenced to be groove binding and in partial intercalative mode.

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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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27

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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28

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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29

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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30

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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31

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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32

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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33

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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34

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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35

Suresh Kumar, H. M., R. S. Kunabenchi, J. S. Biradar, N. N. Math, J. S. Kadadevarmath, and S. R. Inamdar. "Analysis of fluorescence quenching of new indole derivative by aniline using Stern–Volmer plots." Journal of Luminescence 116, no. 1-2 (January 2006): 35–42. http://dx.doi.org/10.1016/j.jlumin.2005.02.012.

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36

Boßmann, Stefan, Martin Seiler, and Heinz Dürr. "Supramolecular sensitizer-relay assemblies. An evaluation of binding constants from non-linear stern-volmer plots." Journal of Physical Organic Chemistry 5, no. 2 (February 1992): 63–73. http://dx.doi.org/10.1002/poc.610050202.

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37

Keizer, Joel. "Additions and Corrections - Nonlinear Fluorescence Quenching and the Origin of Positive Curvature in Stern-Volmer Plots." Journal of the American Chemical Society 107, no. 18 (September 1985): 5319. http://dx.doi.org/10.1021/ja00304a601.

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38

Blatt, E., R. C. Chatelier, and W. H. Sawyer. "Effects of Quenching Mechanism and Type of Quencher Association on Stern-Volmer Plots in Compartmentalized Systems." Biophysical Journal 50, no. 2 (August 1986): 349–56. http://dx.doi.org/10.1016/s0006-3495(86)83468-3.

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39

Hájková, Hana, and Zdeněk Pavlíček. "Generation of electronically excited states by means of methemoglobin and methemoglobin-haptoglobin complex." Collection of Czechoslovak Chemical Communications 55, no. 4 (1990): 1119–26. http://dx.doi.org/10.1135/cccc19901119.

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It has been found that both human methemoglobin and its complex with human haptoglobin in their enzymatic action can generate products in electronically excited states. The time dependence has been measured of the chemiluminescence generated by both the haem proteins in their peroxidase as well as oxidase actions. The methemoglobin-haptoglobin complex exhibited, in its peroxidase action, a higher chemiluminescence as compared with methemoglobin alone. The chemiluminescence observed in the oxidase reaction was the same with both the haem proteins. The Stern-Volmer plots for quenching of chemiluminescence with indole and acrylamide have been constructed for both enzymatic reactions.

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40

Klavins, M., L. Ansone, O. Purmalis, and A. Zicmanis. "Characterization of interaction between tricyclic structures containing pharmaceuticals, their models and humic substances." Water Science and Technology 63, no. 5 (March 1, 2011): 845–52. http://dx.doi.org/10.2166/wst.2011.119.

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Their persistence and wide consumption identify pharmaceuticals as “emerging pollutants”. The complexation of pharmaceuticals containing adamantine ring structures and their model substances with humic acids (HA) of different origins was compared using fluorescence spectroscopy as a function of pH, humic acid concentration, ionic strength, and molecular mass of HA. Binding constants between the studied pharmaceuticals and humic acids were calculated. A combination of dynamic and static quenching processes as indicated by nonlinear Stern-Volmer plots and high Kd values were positively correlated with the concentration of carboxyl groups in the studied humic acids. For basic functional group-containing pharmaceuticals, the complexation was driven by cation exchange and hydrophobic interactions depending on the properties of the interacting compounds.

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41

Will, A. Yvette, Arsenio Muñoz De La Peña, Thilivhali T. Ndou, and Isiah M. Warner. "Influence of Triethanolamine on Aqueous β-Cyclodextrin/Pyrene Complexes." Applied Spectroscopy 49, no. 4 (April 1995): 520–25. http://dx.doi.org/10.1366/0003702953964192.

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The influence of triethanolamine (TEA) on the aqueous β-CD/pyrene fluorescence is examined. Collisional quenching of pyrene by TEA is indicated by Stern-Volmer plots. However, a decrease in the quenching is observed in the presence of β-cyclodextrin, which indicates an effective protection of the included pyrene molecules against quenching from TEA. A decrease in the apparent formation constant of the β-CD/pyrene complex also occurs in the presence of TEA. This phenomenon is attributed to a combination of an increased bulk solvent hydrophobicity and a competitive equilibrium between pyrene and TEA for the β-CD cavity. The present study indicates that TEA is not co-included in the β-CD/pyrene complex.

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42

Patil, N. R., R. M. Melavanki, S. B. Kapatkar, K. Chandrashekhar, H. D. Patil, and Siva Umapathy. "Fluorescence quenching of biologically active carboxamide by aniline and carbon tetrachloride in different solvents using Stern–Volmer plots." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 79, no. 5 (September 2011): 1985–91. http://dx.doi.org/10.1016/j.saa.2011.05.104.

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43

Ferrie, Ryan P., Gregory E. Hewitt, and Bruce D. Anderson. "A Fluorescence Quenching Analysis of the Binding of Fluoroquinolones to Humic Acid." Applied Spectroscopy 71, no. 11 (June 30, 2017): 2512–18. http://dx.doi.org/10.1177/0003702817715655.

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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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44

AMAO, YUTAKA, KEISUKE ASAI, and ICHIRO OKURA. "Novel optical oxygen sensing by phosphorescence quenching of palladium porphyrin self-assembled film on alumina plate." Journal of Porphyrins and Phthalocyanines 04, no. 02 (March 2000): 179–84. http://dx.doi.org/10.1002/(sici)1099-1409(200003)4:2<179::aid-jpp178>3.0.co;2-a.

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An optical oxygen sensor based on the phosphorescence quenching of palladium tetrakis(4-carboxyphenyl)porphyrin (PdTCPP) self-assembled film (SAM) on alumina plate was developed. The phosphorescence intensity of PdTCPP film decreased with increasing oxygen pressure, indicating that the film can be used as an optical oxygen-sensing device based on phosphorescence quenching by oxygen. The ratio I0/I100 as a sensitivity measure of the sensing film is estimated to be 17.7, showing that the film is a highly sensitive device for oxygen pressure. The film obeyed Stern–Volmer plots with a multisite model and possessed good operational stability and a fast response. Response times are 36 s for deoxygenated to oxygenated conditions and 148 s for the reverse conditions.

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45

Vargas, Franklin, and Carlos Rivas. "Photochemical formation of oxetanes derived from aromatic ketones and substituted thiophenes and selenophenes." International Journal of Photoenergy 2, no. 2 (2000): 97–101. http://dx.doi.org/10.1155/s1110662x00000131.

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The photochemical formation of oxetanes from different heterocycles have been investigated for many years in this laboratory. Thus far, only correlation between quenching effect of the heterocycles and capability of forming oxetanes have been established but no attempts have been made to elucidate from these data the different mechanistic pathways that lead from starting materials to product in various cases. In the light of kinetic as well as ionization potential information an attempt is made in this review to establish the mechanisms involved in these reactions. By means of the studies of the Stern-Volmer plots, the quenching constants of the reaction of Paternò-Büchi between substituted thiophene and selenophene with aromatic ketones and their relationship with the potentials of ionization of these heterocycles we can infer in the efficient synthesis of oxetanes.

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46

Deepa, H. R., J. Thipperudrappa, and H. M. Suresh Kumar. "A study on fluorescence quenching of a laser dye by aromatic amines in alcohols." Canadian Journal of Physics 93, no. 4 (April 2015): 469–74. http://dx.doi.org/10.1139/cjp-2014-0190.

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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.

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47

Kneas, Kristi A., J. N. Demas, B. A. DeGraff, and Ammasi Periasamy. "Fluorescence Microscopy Study of Heterogeneity in Polymer-supported Luminescence-based Oxygen Sensors." Microscopy and Microanalysis 6, no. 6 (November 2000): 551–61. http://dx.doi.org/10.1007/s100050010052.

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AbstractDespite the great potential of fluorescence microscopy, its application to date has largely been in the study of biological specimens. It will be shown that conventional fluorescence microscopy provides an invaluable tool with which to study the photophysics of polymer-supported luminescence-based oxygen sensors. The design of the imaging system, the measurement methods, and the data analysis used in the investigation of sensor systems are described. Fluorescence microscopic images of sensor films in which microheterogeneous regions exhibiting enhanced luminescence intensity and poorer oxygen quenching relative to the bulk response are shown. This is the first direct evidence that sensor molecules in various domains of the polymer support can exhibit different oxygen quenching properties. It will be shown that μ- and nano-crystallization of the sensor molecule are the probable source of both the observed heterogeneous microscopic responses and the microscopic and macroscopic nonlinear Stern-Volmer plots. The implications of these results in the rational design of luminescence-based oxygen sensors are discussed.

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48

Song, Yongbo, Yulan Niu, Hongyan Zheng, and Ying Yao. "Interaction of Bis-Guanidinium Acetates Surfactants with Bovine Serum Albumin Evaluated by Spectroscopy." Tenside Surfactants Detergents 58, no. 3 (May 1, 2021): 187–94. http://dx.doi.org/10.1515/tsd-2020-2283.

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Abstract The interactions between cocopropane bis-guanidinium acetates, tallowpropane bis-guanidinium acetates with bovine serum albumin (BSA) in an aqueous solution were studied by fluorescence and circular dichroic spectroscopy measurements. The aim of the study was to elucidate the influence of the hydrophilic group and the length of the hydrophobic chain of these surfactants on the mechanism of binding to BSA. The results revealed that for both surfactants, at low concentrations, the Stern–Volmer plots had an upward curvature and at high concentrations, the quenching efficiency was decreased with increase in surfactant concentration. Different thermodynamics parameters demonstrated the existence of hydrogen bond and van der Waals force which acting as binding forces. Static quenching was observed among the protein and surfactant. The conformation of BSA was changed at higher surfactant concentrations as shown by synchronous fluorescence and CD spectroscopy. This work reveals the mechanism and binding characteristics between guanidine surfactants and protein, and provided the basis for further applications of surfactants.

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49

Hu, Zijun, Yifeng Ni, Li Huang, Xueyu Jiang, Xiaoyun Yang, Chenglei Li, Qi Wu, Xianyin Zeng, and Kuan Liu. "Meta-linked cationic poly(pyridinylene vinylene) conjugated polyelectrolytes: solution photophysics and fluorescent sensing of metal ions." e-Polymers 18, no. 5 (September 25, 2018): 453–64. http://dx.doi.org/10.1515/epoly-2018-0022.

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AbstractTwo novel poly(pyridinylene vinylene) (PPV)-type conjugated polyelectrolytes 2,6-PPYPV-(2+) and 3,5-PPYPV-(2+) were synthesized via Heck coupling reaction and characterized by 1H nuclear magnetic resonance (NMR), ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy. The two polymers consisting of meta-position substituted pyridinylenes as the metal recognition unit and a water-soluble divinyl-benzene derivative in the backbones. 2,6-PPYPV-(2+) and 3,5-PPYPV-(2+) both exhibit strongest fluorescence in methanol and weakest fluorescence in water among common polar solvents. In respect of ion detection, 3,5-PPYPV-(2+) has an excellent identifiability for Pd2+ in methanol with the K_SV value of 1.1×105m−1 while 2,6-PPYPV-(2+) has a good selectivity for Cu2+ and Hg2+ in aqueous solution. And all the Stern-Volmer plots of 2,6-PPYPV-(2+) and 3,5-PPYPV-(2+) in fluorescence quenching for metal ions have favorable tendencies. All the results suggest that 2,6-PPYPV-(2+) and 3,5-PPYPV-(2+) are promising materials in the applications of high performance chemosensors for some specific metal ions.

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50

Melavanki, Raveendra M. "Fluorescence quenching of a biologically active boronic acid derivative by aniline in different solvents." Canadian Journal of Physics 96, no. 6 (June 2018): 603–9. http://dx.doi.org/10.1139/cjp-2017-0466.

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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.

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Journal articles on the topic 'Stern-Volmer Plot'

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