Copper(II) Complexes Bearing 2-Amino Benzothiazole and Phenoxyacetic Acid Derivatives:Coordination Modes and Antimicrobial Activity

Three ternary complexes,namely [Cu(pa)2(aben)2](1,pa=phenoxyacetic acid anion,aben=2-amino benzothiazole),[Cu2(pnpa)4(aben)2](2,pnpa=p-nitrylphenoxyacetic acid anion) and [Cu(pmpa)2(aben)2]·[Cu2(pmpa)4(aben)2](3,pmpa=p-methylphenoxyacetic acid anion),were synthesized by the reaction of copper acetate,2-amino benzothiazole and corresponding phenoxyacetic acid derivatives.Elemental analysis,IR spectra and X-ray single-crystal diffraction were used to determine the compositions and crystal structures.Studies reveal that the copper(Ⅱ) ion in complex 1 is four-coordinated with two carboxyl oxygen atoms of the two pa ligands and two nitrogen atoms from thiazole rings of the two aben ligands.In binuclear complex 2,each central copper(Ⅱ) ion is five-coordinated with four carboxyl oxygen atoms from four pnpa ligands and one nitrogen atom from thiazole ring of one aben ligand,but the two carboxyl oxygen atoms of every pnpa ligand take part in the coordination with different copper(Ⅱ) ions,which result in the formation of two eight-numbered rings in a unit cell.In trinuclear complex 3,there are four-coordinated and five-coordinated copper(Ⅱ) ions as described in the complex 1 and 2.Structure analysis shows that there are intermolecular and intramolecular hydrogen bondings between amino-nitrogen atoms and carboxyl oxygen atoms(or even ether oxygen atoms in complex 3).Results of antimicrobial tests show that three copper complexes exhibit significant antifungal activities(MIC 1~10 μg·mL-1) that are better than that of their original free ligands,and there are some differences in their antifungal properties,whichare caused by the orienting substituted groups in the phenoxyacetic acid ligands.CCDC: 831015,1;831017,2;831016,3.