Assessment of various density functionals and solvation models to describe acid-base, spectral and complexing properties of thiobarbituric and barbituric acids in aqueous solution

Lutoshkin, Maxim A.; Kazachenko, Аleksandr S.

doi:10.3233/jcm-170745

Cited by 15 publications

(7 citation statements)

References 36 publications

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“…The density functional theory (DTF) [ 87 , 88 ] is widespread in the theoretical examination of the physicochemical characteristics of natural substances. Here, the calculation of spectroscopic properties is of great importance for predicting the relevant physicochemical characteristics [ 89 , 90 , 91 , 92 ].…”

Section: Resultsmentioning

confidence: 99%

Sulfation of Wheat Straw Soda Lignin with Sulfamic Acid over Solid Catalysts

et al. 2022

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Soda lignin is a by-product of the soda process for producing cellulose from grassy raw materials. Since a method for the industrial processing of lignin of this type is still lacking, several research teams have been working on solving this problem. We first propose a modification of soda lignin with sulfamic acid over solid catalysts. As solid catalysts for lignin sulfation, modified carbon catalysts (with acid sites) and titanium and aluminum oxides have been used. In the elemental analysis, it is shown that the maximum sulfur content (16.5 wt%) was obtained with the Sibunit-4® catalyst oxidized at 400 °C. The incorporation of a sulfate group has been proven by the elemental analysis and Fourier-transform infrared spectroscopy. The molecular weight distribution has been examined by gel permeation chromatography. It has been demonstrated that the solid catalysts used in the sulfation process causes hydrolysis reactions and reduces the molecular weight and polydispersity index. It has been established by the thermal analysis that sulfated lignin is thermally stabile at temperatures of up to 200 °C. According to the atomic force microscopy data, the surface of the investigated film consists of particles with an average size of 50 nm. The characteristics of the initial and sulfated β-O-4 lignin model compounds have been calculated and recorded using the density functional theory.

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Section: Resultsmentioning

confidence: 99%

Sulfation of Wheat Straw Soda Lignin with Sulfamic Acid over Solid Catalysts

et al. 2022

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“…For theoretical description, we have chosen several density functionals (PBE0, revTPSS, TPSS, B3LYP, CAM-B3LYP, M06, M05-2X, M06-2X, and M06-HF). All of them have a significant weight of the Hartree–Fock exchangean important factor for the assessment of systems with π-electron delocalization . These functionals were successfully used for describing similar systems …”

Section: Resultsmentioning

confidence: 99%

“…All of them have a significant weight of the Hartree−Fock exchangean important factor for the assessment of systems with π-electron delocalization. 67 These functionals were successfully used for describing similar systems. 52 Table 5 contains the results of theoretical simulations (TD-DFT) of spectral properties.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Determination of Acid–Base and Complexing Parameters of Chlorine-Substituted Trifluorobenzoylacetone in Water Medium

Lutoshkin

Malyar

2020

J. Chem. Eng. Data

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In this work, we study the behavior of 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione (ClTFBA) using a spectrophotometric technique under various conditions. Acid–base characteristics have been studied in citrate-phosphate buffer and hydrochloric acid solutions. Dissociation constants were determined in the pH range 3.0–8.0 for three ionic strengths (I = 0.1, 0.5, and 1.0 M; NaCl). Protonation equilibria have been investigated in concentrated HCl by the nonlinear Cox–Yeats method. The interaction between ClTFBA and rare-earth metals was examined in glycine and acetate buffers. Stability constants of monocomplexes were obtained for trivalent metalsSc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The received formation constants lie from 4.5 to 11.8 logarithmic units. Analysis of the results shows that the thermodynamic stability of complexes increased from Ce(III) to Lu(III) and has a linear correlation with the ionic potential. The relationship described in this work demonstrates the electrostatic nature of the M(III)–ClTFBA bonds. Pronounced ionic character, observed for complexes with Ce, Pr, Nd, Sm, Eu, and Gd, points to high charge carrier mobility for these compounds and iterates the appropriateness to use the studied complexes to generate new organic light-emitting diode materials. Equilibrium and spectral characteristics were reproduced by density functional theory (DFT) and time-dependent DFT calculations performed using different basis sets and exchange–correlation functionals.

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“…The free energies of complexation (ΔΔG solv ) have been calculated taken into account in three parts: gas-phase energy (ΔG gas ), solvation free energy (ΔG aq ), and zero-point energy correction (ΔE ZPE ): 41 Here, E corr is a term for the free energy change associated with moving a solvent from a standard-state solution-phase concentration of 1 M to a standard state of the pure liquid, 55.34 M. 42 The values of G gas (H + ) and ΔG solv (H + ) for proton (−26.28 and −1108.27 kJ/mol, respectively) have been taken from previous research. 43 The solvent effects were evaluated using the SMD solvation model. 44 All theoretical calculations were performed with a temperature of 298 K. The UV−vis absorption maximum wavelengths of complex species were reproduced from the vertical excitation energies for the first 11 singlet excited states by time-dependent DFT (TD-DFT).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Interaction of Rare-Earth Metals and Some Perfluorinated β-Diketones

et al. 2021

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In this work, we demonstrate the fundamental relationships between stability constants and periodic, acid–base, and structural parameters for complexes of some 1,3-diketones. The four analogues of hexafluoroacetylacetone2-thenoyltrifluoroacetone, 2-furoyltrifluoroacetone, benzoyltrifluoroacetone, and 2-naphthyltrifluoroacetonehave been studied as chelating ligands for 16 rare-earth metals (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in aqueous solutions. Systems have been investigated spectrophotometrically using a multiwave nonlinear least-squares regression algorithm for data processing. Conditional stability constants were obtained for a wide pH region (2.0–5.4) at constant ionic strength (I = 0.5 M, NaCl). To receive the apparent (“true”) equilibrium parameters, acid–base and keto–enol characteristics of the studied ligands have been described and revised for specific conditions. Dissociation constants were obtained in citrate–phosphate buffer media and protonation parameters were received in concentrated hydrochloric acid by the Cox–Yates method. The apparent formation constants for monocomplex species were obtained as thermodynamic invariants (depend only on the temperature) for each ligand and lie from 4.2 to 12.7 logarithmic units. Although the studied ligands have similar values of pK a, the stabilities of their complexes vary considerably. Systematic analysis of 64 apparent stability constants demonstrates that the force of interaction between the metals and nonsymmetric β-diketones increases as 2-furoyltrifluoroacetone < 2-thenoyltrifluoroacetone < benzoyltrifluoroacetone < 2-naphthyltrifluoroacetone. The studied ligands display varying degrees of the correlation between the periodic parameters and formation constants. Naphthyltrifluoroacetone and its complexes with heavy lanthanides exhibit a clear trend in properties with increasing ionic potential. In general, the received set of data can be described from purely electrostatic grounds within the framework of the periodic law. Spectral, keto–enol, acid–base, and complexing properties were reproduced using density functional theory modeling and explain some of the regularities discovered.

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Assessment of various density functionals and solvation models to describe acid-base, spectral and complexing properties of thiobarbituric and barbituric acids in aqueous solution

Cited by 15 publications

References 36 publications

Sulfation of Wheat Straw Soda Lignin with Sulfamic Acid over Solid Catalysts

Sulfation of Wheat Straw Soda Lignin with Sulfamic Acid over Solid Catalysts

Determination of Acid–Base and Complexing Parameters of Chlorine-Substituted Trifluorobenzoylacetone in Water Medium

Interaction of Rare-Earth Metals and Some Perfluorinated β-Diketones

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