Spectroscopic and antimicrobial studies of La3+, Pr3+, Nd3+ and Gd3+ complexes of a dipodal [N,N,N] chelating ligand.

The lanthanide complexes of bis(benzimidazole-2'-yl-methyl)amine (BImz) having molecular formula [M(BImz)X(3)H(2)O]*nH(2)O (M = La, Pr, Nd, or Gd; X = Cl or ClO(4) and n = 1, 2 or 3) were prepared and characterized spectroscopically through IR, (1)H and (13)C NMR, FAB-mass, UV-visible and luminescence spectroscopy. TGA data suggested presence of coordinated and the lattice water. The oscillator strengths of the f-f transitions and the covalency parameters (beta, b(1/2) and delta) have been evaluated from the electronic spectral data. The proposed hepta-coordinate geometry for the complexes has been ascertained from the molecular model computations. CV studies indicate formation of a stable quasi-reversible redox couple Gd(III/IV) in the solution. The in vivo antimicrobial activities of the complexes have been evaluated against gram +ve and gram -ve bacteria and fungi.