Experimental and theoretical approach: Chemical activity, charge transfer of DNA/ECT, thermodinamic, spectroscopic, structural and electronic properties of N-(4-(3-methyl-3-phenylcyclobutyl)thiazol-2-yl)acetamide molecule

Effect of Substituents on Molecular Reactivity during Lignin Oxidation by Chlorine Dioxide: A Density Functional Theory Study

Lignin is a polymer with a complex structure. It is widely present in lignocellulosic biomass, and it has a variety of functional group substituents and linkage forms. Especially during the oxidation reaction, the positioning effect of the different substituents of the benzene ring leads to differences in lignin reactivity. The position of the benzene ring branched chain with respect to methoxy is important. The study of the effect of benzene substituents on the oxidation reaction's activity is still an unfinished task. In this study, density functional theory (DFT) and the m062x/6-311+g (d) basis set were used. Differences in the processes of phenolic oxygen intermediates formed by phenolic lignin structures (with different substituents) with chlorine dioxide during the chlorine dioxide reaction were investigated. Six phenolic lignin model species with different structures were selected. Bond energies, electrostatic potentials, atomic charges, Fukui functions and double descriptors of lignin model substances and reaction energy barriers are compared. The effects of benzene ring branched chains and methoxy on the mechanism of chlorine dioxide oxidation of lignin were revealed systematically. The results showed that the substituents with shorter branched chains and strong electron-absorbing ability were more stable. Lignin is not easily susceptible to the effects of chlorine dioxide. The substituents with longer branched chains have a significant effect on the flow of electron clouds. The results demonstrate that chlorine dioxide can affect the electron arrangement around the molecule, which directly affects the electrophilic activity of the molecule. The electron-absorbing effect of methoxy leads to a low dissociation energy of the phenolic hydroxyl group. Electrophilic reagents are more likely to attack this reaction site. In addition, the stabilizing effect of methoxy on the molecular structure of lignin was also found.

Density Functional Theory Interaction Study of a Polyethylene Glycol-Based Nanocomposite with Cephalexin Drug for the Elimination of Wound Infection

In this paper, density functional theory (DFT) simulations are used to evaluate the possible use of a graphene oxide-based poly(ethylene glycol) (GO/PEG) nanocomposite as a drug delivery substrate for cephalexin (CEX), an antibiotic drug employed to treat wound infection. First, the stable configuration of the PEGylated system was generated with a binding energy of -25.67 kcal/mol at 1.62 Å through Monte Carlo simulation and DFT calculation for a favorable adsorption site. The most stable configuration shows that PEG interacts with GO through hydrogen bonding of the oxygen atom on the hydroxyl group of PEG with the hydrogen atom of the carboxylic group on GO. Similarly, for the interaction of the CEX drug with the GO/PEG nanocomposite excipient system, the adsorption energies are computed after determining the optimal and thermodynamically favorable configuration. The nitrogen atom from the amine group of the drug binds with a hydrogen atom from the carboxylic group of the GO/PEG nanocomposite at 1.75 Å, with an adsorption energy of -36.17 kcal/mol, in the most stable drug-excipient system. Drug release for tissue regeneration at the predicted target cell is more rapid in moist conditions than in the gas phase. The solubility of the suggested drug in the aqueous media around the open wound is shown by the magnitude of the predicted solvation energy. The findings from this study theoretically validate the potential use of a GO/PEG nanocomposite for wound treatment application as a drug carrier for sustained release of the CEX drug.

Crystal structure and Hirshfeld surface analysis of (Z)-4-{[4-(3-methyl-3-phenyl-cyclo-but-yl)thia-zol-2-yl]amino}-4-oxobut-2-enoic acid

The title cyclo-butyl compound, C18H18N2O3S, was synthesized by the inter-action of 4-(3-methyl-3-phenyl-cyclo-but-yl)thia-zol-2-amine and maleic anhydride, and crystallizes in the ortho-rhom-bic space group P212121 with Z' = 1. The mol-ecular geometry is partially stabilized by an intra-molecular N-H⋯O hydrogen bond forming an S 1 1(7) ring motif. The mol-ecule is non-planar with a dihedral angle of 88.29 (11)° between the thia-zole and benzene rings. In the crystal, the mol-ecules are linked by O-H⋯N hydrogen bonds, forming supra-molecular ribbons with C 1 1(9) chain motifs. To further analyze the inter-molecular inter-actions, a Hirshfeld surface analysis was performed. The results indicate that the most important contributions to the overall surface are from H⋯H (43%), C⋯H (18%), O⋯H (17%) and N⋯H (6%), inter-actions.