Synthesis and crystal structures of copper, nickel and zinc complexes derived from 2-((2-(pyrrolidin-1-yl)ethylimino)methyl)phenol with antimicrobial activity

Five new copper(II), nickel(II) and zinc(II) complexes, [Cu4Cl2(mu 1,1-N3)4(DMF)2] (1), [Cu4Br2(mu 1,1-N3)4(DMF)2] (2), [Ni3L2(CH3COO)4]CH3OH (3),[Ni3L2(CH3COO)2(mu 1,1-N3)2(CH3OH)2] (4) and [Zn(LH)I2]CH3OH (5), were designed and successfully synthesized using the Schiff base ligand 2-((2-(pyrrolidin-1-yl)ethylimino)methyl) phenol (HL). All the synthesized complexes were characterized using different physico-chemical and spectro-scopic methods, like elemental analysis, infrared spectra and single crystal X-ray diffraction. The X-ray structural analysis showed that the Cu atoms in the tetranuclear complexes 1 and 2 are in a square pyramidal coordination, the Ni atoms in the trinuclear complexes 3 and 4 are in an octahedral coordination and the Zn atom in the mononuclear complex 5 is in a tetrahedral coordination. The Schiff base ligand was coordinated to the metal atoms through the phenolate oxygen, imino nitrogen and/or pyrrolidine nitrogen atoms. The biological study indicated that the copper and zinc complexes have interesting antimicrobial activity against B. subtilis, S. aureus, E. coli and P. fluorescens, with MIC values of 0.6-2.3 mu mol/L.