Synthesis, characterisation and antimicrobial activity of new palladium and nickel complexes containing Schiff bases

New Schiff base ligands were synthesized by condensation of 2-(3,4-dimethoxyphenyl)ethanamine with 2-hydroxy benzaldehyde ((LH)-H-1) and 2'-hydroxy acetophenone ((LH)-H-2) respectively. Reaction of (LH)-H-1 or (LH)-H-2 with Na2PdCl4 or NiCl2 center dot 6H(2)O in 2:1 ratio obtained four new coordination complexes [M(L1-2)(2)] (where M = Pd(II); 1 and 2 and M = Ni(II); 3 and 4). Both the ligands and four complexes were characterised by elemental analysis, FT-IR and UV-Vis, spectroscopy. (LH)-H-1, (LH)-H-2, 1 and 2 were also characterised by H-1 and C-13{H-1} NMR spectroscopy. The molecular structures of 1 and 3 were determined by single crystal X-ray diffraction. The spectroscopic and crystal structure data showed that the ligands coordinated to M (II) ion in a bidentate monoanionic (O , N) fashion. The Pd-O and Pd-N bond lengths in 1 are 1.984(11) and 2.020(12) angstrom in 3 the Ni-O and Ni-N bond lengths are 1.8222(13) and 1.9262(15) angstrom respectively. The C=N bond length in 3 found 1.290(2) angstrom which was shorter than 1.310(19) angstrom in 1. The bond angles provided square planar geometry around Pd(II) and Ni(II) in both 1 and 3. There exists C-H center dot center dot center dot O type (2.50-2.52 angstrom) intermolecular hydrogen bonding in both 1 and 3 resulting in supramolecular structures. The antimicrobial activity of new Schiff base ligands and their Pd(II) and Ni(II) complexes against pathogenic microbial strains by agar well diffusion method was conducted. All the ligands and complexes showed significant antibacterial and antifungal activities. The bacterial and fungi growth inhibition activity of ligands has been increased on complexation as well as among complexes palladium complexes were found better antibacterial and antifungal agents than the nickel complexes of corresponding ligands. Ligand (LH)-H-1 and the complex 2 showed highest antibacterial activity against Pseudomonas desmolyticum and highest antifungal activity against Candida albicans. (C) 2015 Elsevier B.V. All rights reserved.