Synthesis, Crystal Structures, and Biological Activity of Manganese(III) Complexes Derived from BIS-Schiff Bases

Abstract

Two new manganese(III) complexes, [MnIIIL1(Dca)(MeOH)] (I) and [MnIIIL2(N3)2] (II), where L1 and L2 are the dianionic form of N,N'-3,4-chlorophenylene-bis(5-methylsalicylaldimine) (H2L1) and N,N'-3,4-nitrophenylene-bis(5-methylsalicylaldimine) (H2L2), respectively, and Dca is dicyanoamide, have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, UV-Vis spectra, molar conductivity, and single crystal X-ray diffraction (CIF files nos. 1054200 (I), 1054336 (II)). The Mn atoms in the structures are in octahedral coordination. In the crystal structure of complex I, molecules are linked through intermolecular O–H···N hydrogen bonds to form 1D chains running along the x axis. In both complexes, there exist π···π interactions among molecules. The complexes and the Schiff bases were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method.