A series of linear dipeptide derivatives (4–10) were prepared and evaluated as antimicrobial agents via the synthesis of N-(2-(2-hydrazinyl-2-oxoethylamino)-2-oxoethyl) nicotinamide (4). Compound 4 was reacted with 4-chlorobenzaldehyde or 4-hydroxybenzaldehyde, to give the hydrazones 5 and 6, respectively. On the other hand, Compound 4 was coupled with phenylisocyanate or methylisothiocyanate to give Compounds 7 and 8, respectively. The latter compounds (7 and 8) were coupled with chloroacetic acid to give oxazolidine (9) and thiazolidine (10), respectively. The newly synthesized dipeptide compounds were confirmed by means of their spectral data. The antimicrobial activity of the newly synthesized compounds 4–10 was evaluated by agar well diffusion, and they showed good activity. Compounds 4, 5, and 9 gave the most promising activity in this study. Most of the tested compounds possessed MIC values ranging from 50 to 500 µg/mL. Furthermore, docking studies were carried out on enoyl reductase from E. coli and cytochrome P450 14 α-sterol demethylase (Cyp51) from Candida albicans active sites. The MolDock scores of the seven tested compounds ranged between −117 and −171 and between −107 and −179, respectively.

In this article, four new Schiff base complexes of Mn(II), Co(II), Ni(II) and Cu(II) complexes have been synthesized with two different compositions as [M(L)2Cl2] · nH2O and [M(L)2(H2O)2]Cl2 · nH2O [where L1 = benzoin-o-amino benzoic acid (aromatic β amino acid) and L2 = benzoin bromo-o-amino benzoic acid (aromatic β amino acid); M = MnII, CoII, NiII and CuII; n = 1, 2 and 4]. These Schiff base complexes were discussed by many tool of analyses like elemental analysis, magnetic susceptibility, molar conductance, mass spectra, infrared spectra "IR," proton nuclear magnetic resonance "1H-NMR," electronic spectral and thermogravimetric analysis (TG/DTG). These complexes have an electrolytic nature within range of 78–174 Ω1 cm–1 mol –1 based on conductance measurements. Magnetic moment and electronic spectral results deduced that the geometry of Mn2+, Co2+ and Ni2+ and Cu2+ complexes has an octahedral configuration. The number of coordinated and uncoordinated water molecules for the synthesized complexes were calculated based on the thermal analysis technique. The kinetic thermodynamic data were estimated by using commonly integral equations of Horowitz-Metzger (HM) and Coats-Redfern (CR). In vitro the antimicrobial activity of both free L1 and L2 ligands in comparable with their metal complexes were evaluated. This study was strengthen by molecular docking against three protein receptors, which attributing to selected organisms already used in vitro study.

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Morpholine is an interesting moiety that used widely in several organic syntheses. The intermolecular charge-transfer (CT) complexity associated between morpholine (Morp) donor with (monoiodobromide “IBr”, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone “DDQ”, 2,6-dichloroquinone-4-chloroimide “DCQ” and 2,6-dibromoquinone-4-chloroimide “DBQ”) π–acceptors have been spectrophotometrically investigated in CHCl3 and/or MeOH solvents. The structures of the intermolecular charge-transfer (CT) were elucidated by spectroscopic methods like, infrared spectroscopy. Also, different analyses techniques such as UV-Vis and elemental analyses were performed to characterize the four morpholine [(Morp)(IBr)], [(Morp)(DDQ)], [(Morp)(DCQ)] and [(Morp)(DBQ)] CT-complexes which reveals that the stoichiometry of the reactions is 1:1. The modified Benesi-Hildebrand equation was utilized to determine the physical spectroscopic parameters such as association constant (K) and the molar extinction coefficient (ε).

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