scholarly journals Thermodynamic Study of Oxidovanadium(IV) with Kojic Acid Derivatives: A Multi-Technique Approach

2021 ◽  
Vol 14 (10) ◽  
pp. 1037
Author(s):  
Rosita Cappai ◽  
Guido Crisponi ◽  
Daniele Sanna ◽  
Valeria Ugone ◽  
Andrea Melchior ◽  
...  
Keyword(s):  
Complex Formation ◽  
Kojic Acid ◽  
Formation Constants ◽  
Biological Action ◽  
Binuclear Complexes ◽  
Complex Formation Equilibria ◽  
Complex Formation Constants ◽  
Coordination Model ◽  
Starting Point ◽  
Pharmacologically Active

The good chelating properties of hydroxypyrone (HPO) derivatives towards oxidovanadium(IV) cation, VIVO2+, constitute the precondition for the development of new insulin-mimetic and anticancer compounds. In the present work, we examined the VIVO2+ complex formation equilibria of two kojic acid (KA) derivatives, L4 and L9, structurally constituted by two kojic acid units linked in position 6 through methylene diamine and diethyl-ethylenediamine, respectively. These chemical systems have been characterized in solution by the combined use of various complementary techniques, as UV-vis spectrophotometry, potentiometry, NMR and EPR spectroscopy, ESI-MS spectrometry, and DFT calculations. The thermodynamic approach allowed proposing a chemical coordination model and the calculation of the complex formation constants. Both ligands L4 and L9 form 1:1 binuclear complexes at acidic and physiological pHs, with various protonation degrees in which two KA units coordinate each VIVO2+ ion. The joined use of different techniques allowed reaching a coherent vision of the complexation models of the two ligands toward oxidovanadium(IV) ion in aqueous solution. The high stability of the formed species and the binuclear structure may favor their biological action, and represent a good starting point toward the design of new pharmacologically active vanadium species.

Formation of CT complexes and electron transfer from excited molecules of anthracene derivatives to methylviologen in aqueous and micellar media

1987 ◽  
Vol 52 (7) ◽  
pp. 1658-1665
Author(s):  
Viktor Řehák ◽  
Jana Boledovičová
Keyword(s):  
Electron Transfer ◽  
Complex Formation ◽  
Fluorescence Quenching ◽  
Rate Constant ◽  
Formation Constants ◽  
Dynamic Quenching ◽  
Micellar Media ◽  
Complex Formation Constants ◽  
Anthracene Derivatives ◽  
Ct Complexes

Disodium 1,5- and 1,8-anthracenedisulphonate (ADS) and 9-acetylanthracene form coloured CT complexes with methylviologen (MV2+) in aqueous and micellar media. The complex formation constants and molar absorptivities were determined by the Benesi-Hildebrandt method. In the fluorescence quenching, its static component plays the major role. The dynamic quenching component is determined by the rate constant of electron transfer from the S1 state of ADS to MV2+.

Host–Guest interaction of pesticide bifenox with cyclodextrin molecules. An electrochemical study

2009 ◽  
Vol 74 (11-12) ◽  
pp. 1647-1664 ◽  
Author(s):  
Magdaléna Hromadová ◽  
Romana Sokolová ◽  
Lubomír Pospíšil ◽  
Štěpánka Lachmanová ◽  
Nicolangelo Fanelli ◽  
...  
Keyword(s):  
Complex Formation ◽  
Anion Radical ◽  
Formation Constants ◽  
Aprotic Solvents ◽  
Reduction Wave ◽  
Nitroaromatic Compound ◽  
Complex Formation Constants ◽  
Oh Groups ◽  
Stable Anion ◽  
Main Factor

The reduction of nitroaromatic compound bifenox (methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate) was studied in aprotic solvents in the absence or presence of cyclodextrin (CD) molecules of different cavity sizes. βCD and γCD form complexes with bifenox in DMSO with the complex formation constants (5 ± 2) × 102 M–1 [βCD–bifenox] and (3 ± 1) × 102 M–1 [γCD–bifenox], respectively. Bifenox yields a relatively stable anion radical in dimethyl sulfoxide, which is further reduced at more negative potentials by an overall addition of three electrons and four protons to the corresponding phenylhydroxylamine. In the presence of βCD the first reduction wave of bifenox becomes irreversible, it is shifted towards more positive potentials and the uptake of more than one electron is observed (up to four electrons during the exhaustive electrolysis). The first reduction wave of bifenox is not affected by the addition of glucose confirming that a simple availability of protons from the OH groups is not the main factor in further transformation of anion radical in the presence of βCD. The complex formation with βCD facilitates the protonation and additionally protects the molecule from disintegration into 2,4-dichlorophenol. A yield of 2,4-dichlorophenol decreases in the order βCD, γCD and αCD, respectively.

Complex formation and solubility of Pu(IV) with malonic and succinic acids

2009 ◽  
Vol 97 (4-5) ◽  
Author(s):  
Takayuki Sasaki ◽  
Taishi Kobayashi ◽  
I. Takagi ◽  
Hirotake Moriyama ◽  
A. Fujiwara ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Solvent Extraction ◽  
Complex Formation ◽  
Extraction Method ◽  
Formation Constants ◽  
Complex Formation Constants ◽  
Solvent Extraction Method ◽  
Experimental Solubility Data ◽  
Experimental Solubility ◽  
Solubility Products

AbstractThe complex formation constants of tetravalent plutonium ion with malonic and succinic acids in aqueous solution were determined by the solvent-extraction method. Also, by taking the known values of the solubility products, the hydrolysis constants and the formation constants, the experimental solubility data of plutonium in the presence of carboxylates were analyzed.

Comparison of calcium complexation of some carboxylic acids derived from D­glucose and D-fructose

1995 ◽  
Vol 73 (8) ◽  
pp. 1338-1347 ◽  
Author(s):  
Hélène Bazin ◽  
Gérard Descotes ◽  
Alain Bouchu ◽  
Michelle Petit-Ramel
Keyword(s):  
Molecular Structure ◽  
Complex Formation ◽  
Carboxylic Acids ◽  
Formation Constants ◽  
Ion Selective Electrode ◽  
Selective Electrode ◽  
Complex Formation Constants ◽  
Calcium Complexation ◽  
C Nmr

The aim of this work was to compare calcium sequestering behaviour of 11 carboxylic acids derived from carbohydrates, and to study the influence of molecular structure on the calcium complexation. For this purpose, various carboxylic acids derived from methyl D-glucopyranoside, methyl D-fructopyranoside, and methyl D-fructofuranoside were synthesized and studied using an ion selective electrode to determine calcium complex formation constants. Complexation sites of carbohydrate skeletons were determined using 13C NMR. Keywords: Ca(II) complexation, carboxylic acids, fructofuranosides, fructopyranosides, glucopyranosides.

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