Synthesis, X-ray crystallography, computational studies and catecholase activity of new zwitterionic Schiff base derivatives

Abstract

Three new Schiff bases compounds (L1-L2-L3) were synthesized by a condensation reaction in 1:1 molar ratios of dehydroacetic acid (3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione) and 4-fluoro/4chloro/4-bromo aniline in ethanol, the products were obtained in excellent yields. Their structures were characterized by spectroscopic techniques (FT-IR and 1H-NMR) and single-crystal X-ray diffraction. The three compounds display zwitterionic forms, with cationic iminium and anionic enolate groups.The aromatic ring and dehydroacetic acid ring are in a trans position with respect to the C=N bond. Calculations in the framework of the density-functional theory (DFT) were carried out to determine the optimized structures and electronic properties as the HOMO-LUMO energy gap.Hirshfeld surface analysis was used to support the packed crystal lattice 3D network intermolecular forces. The NH form is found to be more stable than OH form. On the other hand, the in situ generated copper (II) complexes were examined for their catalytic activities and were found to catalyze the oxidation reaction of catechol to o-quinone under atmospheric dioxygen. The present study reveals that the rate of oxidation depends on the nature of the substituents in the phenyl ring, the counter anion and the concentration of ligand. The combination L1(Cu(CH3COO)2) gives the highest rate.

New Pyrazole‐Hydrazide Derivatives: Synthesis, Characterization, Highly Active Catecholase‐Like Catalyst, and Antibacterial Study

“…The obtained results unequivocally demonstrate the remarkable catalytic activities exhibited by the in situ formed combinations of L 1 ‐L 11 ligands with various copper salts. These combinations exhibited superior catalytic activities compared to numerous previous studies [57,58,59,60,61,62] . These findings underscore the distinctiveness of the L/M combinations and their potential significance in facilitating the oxidation of catechol.…”

“…These combinations exhibited superior catalytic activities compared to numerous previous studies. [57,58,59,60,61,62] These findings underscore the distinctiveness of the L/M combinations and their potential significance in facilitating the oxidation of catechol.…”

Crystal structure, Hirshfeld surface analysis and DFT calculations of (E)-3-[1-(2-hydroxyphenylanilino)ethylidene]-6-methylpyran-2,4-dione

“…The same is true for each of the bonds labeled b-f and the average values are a = 1.323 (3) A ˚, b = 1.431 (3) A ˚, c = 1.447 (3) A ˚, d = 1.433 (3) A ˚, e = 1.226 (3) A ˚and f = 1.254 (3) A ˚. These compare quite favorably with those found in molecules with R = Me (Gilli et al, 2000) and 4-XC 6 H 4 (X = F, Cl, Br; Boulemche et al, 2019) and accompanied by in depth discussions of the RAHB.…”

Characterizations of crystalline structure and catalytic activity of zwitterionic imidazole derivatives

“…The Rate values in literature show high speed values for isolate complex (1.93 µmol L −1 min −1 ) [20]. We have obtained good result with our in situ complex CuL1 (derived from copper acetate and ligand L1) compared to those of the literature [18,20,26]. In addition, L1 ligand is composed from two planar phenol-imidazole molecules and one phenol molecule.…”

“…A C C E P T E D ACCEPTED MANUSCRIPT ligand type. As a result, studies have reported the use of in situ copper (II) complexes of Schiff base derivatives to produce catecholase activity [26].…”