Preparation, structures and antimicrobial activity of four different type metal complexes on the base of diethanolamine and o-nitrobenzoic acid

Abstract Crystallization under identical conditions from aqueous ethanol solutions of diethanolamine (DEA), o -nitrobenzoic acid (ONBA) and definite metal salt yields 4 different type metal complexes and one organic salt – the monoligand complex of Zn(II) with DEA ( 1 ), monoligand complex of Cu(II) with ONBA ( 2 ), mixed-ligand complex of Ni(II) with DEA and ONBA ( 3 ), supramolecular complex between monoligand complex molecule of Zn(II) with DEA and ONBA ( 4 ) and DEA + ·ONBA − salt ( 5 ). In 1 two meridionally distributed DEA molecules are coordinated by a tridentate mode, 2 is a binuclear copper complex with 4 ONBA molecules which are bidentately coordinated through carboxylate groups. In 3 two DEA and two ONBA molecules are coordinated by bidentate and monodentate fashions, respectively. The compound 4 consists of a complex molecule with two facial distributed tridentate DEA molecules and ONBA ones in an outer sphere. Hence, in coordination compounds 1 and 4 Zn-complex ions with two tridentately coordinated DEA molecules are found in different isomeric forms of which a mer -distribution is recorded for the first time. The maximal enhancement of the ligands antimicrobial activity is observed for the mixed-ligand metal complex. The Zn-complex with mer -distributed ligand molecules demonstrated more antimicrobial activity in contrast to fac -isomer.