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Swapan Kumar Bose

Bio: Swapan Kumar Bose is an academic researcher from University of Calcutta. The author has contributed to research in topics: Equilibrium constant & Hückel's rule. The author has an hindex of 5, co-authored 9 publications receiving 74 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the formation of inclusion complex between lumichrome and β-cyclodextrin was studied by fluorimetric and solubility methods, and the equilibrium constant of formation of this inclusion complex, K, determined by fluorometric method and Solubility method is 966 and 491 mol dm−3, respectively.
Abstract: The formation of inclusion complex between lumichrome and β-cyclodextrin was studied by fluorimetric and solubility methods. The accessibility of lumichrome to the iodide ion in presence of β-cyclodextrin was also studied. The equilibrium constant of formation of this inclusion complex, K, determined by fluorometric method and solubility method is 966 and 491 mol dm−3, respectively.

34 citations

Journal ArticleDOI
TL;DR: In this article, an equilibrium constant was estimated from absorption and emission studies, and also from the solubility of riboflavin in an aqueous solution of sodium salicylate, and was found to be in the range of 10−14 mol dm−3.
Abstract: Evidence for an intermolecular interaction of riboflavin and sodium salicylate in an aqueous medium was obtained from the presence of isosbestic points in the absorption spectra and an isoemissive point in the emission spectra. The equilibrium constant was estimated from absorption and emission studies, and also from the solubility of riboflavin in an aqueous solution of sodium salicylate, and was found to be in the range of 10–14 mol dm−3. Lifetime measurements indicate a predominantly static mechanism of quenching. The Stern–Volmer constant for the quenching of riboflavin by sodium salicylate was significantly reduced upon the addition of urea. An MD simulation study on the system revealed a stacked conformation, which is probably due to a hydrophobic interaction of the two components.

19 citations

Journal ArticleDOI
TL;DR: The equilibrium constants K', for the formation of the molecular association complex between riboflavin and resorcinol in the pH range 6-8 were found to be in the range 5-25 mol(-1)dm(3) by difference absorption spectroscopy and the interaction energies obtained from modeling studies suggest a stacked conformation of the two components in the complexed form.

7 citations

Journal ArticleDOI
TL;DR: The riboflavin sensitized oxidation of cysteine under an aerobic condition was investigated and a reaction mechanism involving the superoxide anion is proposed for the photooxidation of Cysteine to cysteic acid.
Abstract: The riboflavin sensitized oxidation of cysteine under an aerobic condition was investigated. The effects of various scavengers, such as superoxide dismutase, catalase, mannitol, sodium azide and potassium ferrocyanide (an electron donor), on the photooxidation were determined. A reaction mechanism involving the superoxide anion is proposed for the photooxidation of cysteine to cysteic acid.

7 citations

Journal ArticleDOI
TL;DR: Overall equilibrium constants K' for the formation of molecular complexes of riboflavin with the conjugate forms of different aromatic hydroxy compounds are greater in magnitude than those involving the protonated forms of the Hydroxy compounds.

6 citations


Cited by
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Journal ArticleDOI
TL;DR: Fluorescent Dyes and Their Supramolecular Host/Guest Complexes with Macrocycles in Aqueous Solution and how these complexes interact with each other and with solvent-free substrates is studied.
Abstract: Fluorescent Dyes and Their Supramolecular Host/Guest Complexes with Macrocycles in Aqueous Solution Roy N. Dsouza, Uwe Pischel,* and Werner M. Nau* School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany Centro de Investigaci on en Química Sostenible (CIQSO) and Departamento de Ingeniería Química, Química Física y Química Org anica, Universidad de Huelva, Campus de El Carmen s/n, E-21071 Huelva, Spain

897 citations

Journal ArticleDOI
TL;DR: 2H-naphthoxete structure was assigned to naphthoquinone methides 1 and 2 on the basis of the precursor reactivity and the results of DFT calculations, which showed acid catalysis only at pH < 1.
Abstract: Irradiation of 3-hydroxy-2-naphthalenemethanol (3a) and 2-hydroxy-1-naphthalenemethanol (4a) results in efficient (Φ254 = 0.17 and 0.20) dehydration and the formation of isomeric naphthoquinone methides, 2,3-naphthoquinone-3-methide (1) and 1,2-naphthoquinone-1-methide (2), respectively. In aqueous solution, naphthoquinone methides 1 and 2 undergo rapid hydration to regenerate starting materials (τH2O (1) = 7.4 ms and τH2O (2) = 4.5 ms at 25 °C). The hydration reaction is strongly catalyzed by the hydroxide ion but shows acid catalysis only at pH < 1. Reactive intermediates 1 and 2 can be intercepted by other nucleophiles, such as the azide ion (kN3(1) = 2.0 × 104 M−1 s−1 and kN3(2) = 3.0 × 104 M−1 s−1) or thiol (kSH(1) = 2.2 × 105 M−1 s−1 and kSH(2) = 3.3 × 105 M−1 s−1). Ethyl vinyl ether readily reacts with 1 and 2 (kDA(1) = 4.1 × 104 M−1 s−1 and kDA(2) = 6.0 × 104 M−1 s−1) to produce Diels−Alder adducts in excellent yield. o-Naphthoquinone methides 1 and 2 were also generated by photolysis of 3-ethoxym...

107 citations

Patent
11 Sep 2003
TL;DR: In this article, a pharmaceutical composition comprising a co-crystal of an API and a cocrystal former is defined, where the API has at least one functional group selected from ether, thioether, alcohol, thiol, aldehyde, ketone, thioketone, nitrate ester, phosphate ester and sulfate ester.
Abstract: A pharmaceutical composition comprising a co-crystal of an API and a co-crystal former; wherein the API has at least one functional group selected from ether, thioether, alcohol, thiol, aldehyde, ketone, thioketone, nitrate ester, phosphate ester, thiophosphate ester, ester, thioester, sulfate ester, carboxylic acid, phosphonic acid, phosphinic acid, sulfonic acid, amide, primary amine, secondary amine, ammonia, tertiary amine, sp2 amine, thiocyanate, cyanamide, oxime, nitrile diazo, organohalide, nitro, s-heterocyclic ring, thiophene, n-heterocyclic ring, pyrrole, o-heterocyclic ring, furan, epoxide, peroxide, hydroxamic acid, imidazole, pyridine and the co-crystal former has at least one functional group selected from amine, amide, pyridine, imidazole, indole, pyrrolidine, carbonyl, carboxyl, hydroxyl, phenol, sulfone, sulfonyl, mercapto and methyl thio, such that the API and co-crystal former are capable of co-crystallizing from a solution phase under crystallization conditions.

87 citations

Journal ArticleDOI
TL;DR: The reaction between the triplet excited state of riboflavin and amino acids, peptides, and bovine whey proteins was investigated in aqueous solution using nanosecond laser flash photolysis and H-atom abstraction seems to operate at low pH, which with rising pH gradually is replaced by electron transfer from the thiol anion.
Abstract: The reaction between the triplet excited state of riboflavin and amino acids, peptides, and bovine whey proteins was investigated in aqueous solution in the pH range from 4 to 9 at 24 degrees C using nanosecond laser flash photolysis. Only tyrosine and tryptophan (and their peptides) were found to compete with oxygen in quenching the triplet state of riboflavin in aqueous solution, with second-order rate constants close to the diffusion limit, 1.75 x 10(9) and 1.40 x 10(9) L mol(-1) s(-1) for tyrosine and tryptophan, respectively, with beta-lactoglobulin and bovine serum albumin having comparable rate constants of 3.62 x 10(8) and 2.25 x 10(8) L mol(-1) s(-1), respectively. Tyrosine, tryptophan, and their peptides react with the photoexcited triplet state of riboflavin by electron transfer from the tyrosine and tryptophan moieties followed by a fast protonation of the resulting riboflavin anion rather than by direct H-atom abstraction, which could be monitored by time-resolved transient absorption spectroscopy as a decay of triplet riboflavin followed by a rise in riboflavin anion radical absorption. For cysteine- and thiol-containing peptides, second-order rate constants depend strongly on pH, for cysteine corresponding to pKaRSH = 8.35. H-atom abstraction seems to operate at low pH, which with rising pH gradually is replaced by electron transfer from the thiol anion. From the pH dependence of the second-order rate constant, the respective values for the H-atom abstraction (k = 1.64 x 10(6) L mol(-1) s(-1)) and for the electron transfer (k = 1.20 x 10(9) L mol(-1) s(-1)) were determined.

79 citations

Journal ArticleDOI
TL;DR: The hydrotropic solubilization of indomethacin at lower hydrotrope concentration may be attributed to weak ionic interactions while that at higher hydrot rope concentration might be due to molecular aggregation.

72 citations