Facile preparation of the new organic ligands, schiff bases and metal complexes in well

Abstract For mitigating the wide spread antibiotic-resistant bacteria. This study aims: Simple synthesis of new series of coordination metal complexes: Cu(II), Co(II), Sm(III), Gd(III) and Tb(III) from the prepared Schiff base bis-hydrazones ligands I-VIII (derivatives of glyoxal, biacetyl and benzyl-hydroxybenzaldhyde and methoxysalicaldhyde). Structural features derived from elemental analysis (empirical formula), melting point (purity), nuclear magnetic resonance ( 1 H, 13 C) spectra and mass spectra. Vibrational IR spectra confirmed strong bonding between metal ions and ligands assumed the coordination sites are oxygen and nitrogen atoms of carbonyl C = O and azomethine CH = N groups. 1 H-NMR spectra (chemical shift 3.5 ppm-10.388 ppm) confirmed all protons in the Schiff bases. Surface analysis SEM micrographs confirmed modified microstructure of 5 th ligand (LV) on complexation to Cu(II). Complex CuLV showed particle size range 276–367 nm. Optical activities of the metal complexes confirmed from electronic absorption spectra. Cu(II) complexes showed internal charge transfer bands. Powder X-ray diffraction pattern confirmed that CuLV complex formed in nm scale crystal with particle size range 13.91–35.49 nm. This complex is a potent antimicrobial agent in terms of the wide inhibition zone and low minimum inhibitory concentration (MIC) except for the fungi A.Niger and C.Glabrata (MIC 100 µgL −1 and 400 µgL −1 respectively).The promising inhibition of bacteria growth and low MIC suggested this metal complex as a new antibiotic. For its optimized geometry, molecular docking analysis predicted antibacterial activity and confirmed the observed weak antifungal activity corresponding to high MIC for A.Niger and C. Glabrata fungal species .