| Summary: | A new series of some biologically active Cr(III), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) complexes was synthesized from the reaction of Ethyl 6-amino-4-(4-chlorophenyl)-5-cyano-2-methyl-4H-pyran-3-carboxylate <b>(L)</b> with the previous biological metals in the presence of 1,10-phenanthroline monohydrate (<b>Phen</b>). The structures of the obtained <b>L</b> along with their complexes were authenticated by different analytical and spectral techniques. The data prove that <b>L</b> chelates with all metal ions as bidentate through the nitrogen of the amino group and the nitrogen of the cyano group. Furthermore, <b>Phen</b> chelated with metal ions via two nitrogen atoms. The molar conductance values reflect that all complexes are electrolyte, confirming the 1:3 electrolytic natures for trivalent metal ions and 1:2 electrolytic for bivalent metal ions. The thermal stability and the general thermal decomposition pathways of metal complexes, <b>L,</b> and <b>Phen</b> were evaluating according to the thermogravimetric technique. The activation thermodynamic parameters were estimated from TG curves by utilizing Horowitz–Metzger (HM) and Coats–Redfern (CR) techniques. Powder X-ray diffraction (XRD) analysis proved that <b>L</b>, Cu(II), and Zn(II) compounds have a crystalline nature, whereas, Cr(III), Fe(III), Co(II), and Ni(II) complexes are semicrystalline. The investigated compounds were examined in vitro for their antimicrobial activity towards G(+ve) Staphylococcus aureus and Bacillus subtilis and G(−ve) Escherichia coli and Pseudomonas aeruginosa bacteria, and two fungi: Candida albicans and Aspergillus flavus. According to the findings, the Co(II) complex has a significant efficiency toward bacteria, additionally, Cr(III) complex is highly significant towards fungal strains.
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