Manganese(II) Macrocyclic Schiff-Base Complexes Containing Pyridine Moiety: Synthesis and Characterization and Antibacterial Properties

Three new macrocyclic Schiff-base complexes have been prepared via the Mn(II) templated [1+1] cyclocondensation of 2,6-diacetylpyridine (DAP) and appropriate linear amines. All complexes were characterized by IR spectra, elemental analysis, El-Mass and conductivity measurements. The crystal structure of [MnL1(CH3CN)] (ClO4)(2) is also reported and exhibits a slightly distorted pentagonal-pyramidal geometry. Also the synthesized complexes were screened for their antibacterial activity against S. aureus (ATCC 6633), B. cereus (ATCC 7064), C. zeros is (ATCC 373) (gram-positive bacterial strains), E. coli (PTCC 10009), K. pneuomoniae (MTCC 109), and P. vulgaris (lio) (gram-negative bacterial strains). The results show that the antibacterial activity of [MnL3](ClO4)(2) is greater than that of [MnL1(CH3CN)](ClO4)(2) and [MnL2](ClO4)(2). The protonation constants of three tetraamines have been determined potentiometrically in 0.1 mol center dot L-1 KCl at 25 degrees C.