Synthesis and characterization of polymeric Schiff base ligand and its vanadium complex derived from N,N-bipyridinium

Polymeric Schiff bases are an important class of coordination polymers with multidentate donor sites, known to form polychelates with transition metal ions. Basic properties of polymeric Schiff base are due to the azomethine linkage in polymeric backbone. This report deals with the synthesis and characterization of a new polymeric Schiff base ligand and its vanadium complex. The polymeric Schiff base ligand (L) was prepared from reaction of [N,N-bipyridinium bis(methyl salicylaldehyde)] chloride and ethylendiamin. Then by reaction of VO(acac)2 with L the VO- Schiff base polymer was synthesized (scheme1). L and VO- Schiff base polymer were characterized by different methods: FT- IR, UV–Vis, 1H-NMR and CHN. The results of C, H and N analysis agree with the expected values. The IR spectrum provide valuable information regarding the reaction of polymeric Schiff base-ligand with metal atom. The ligand and metal–polychelate were mainly characterized using the azomethine, Ar-OH and V=O bands. The appearance of a broad strong band in the IR spectrum of the ligand in 3000–3400 cm-1 is assigned to Ar-OH stretching vibrations. In the metal–polychelate, this band appears as a weak band. The band at 1598 cm-1 in the FT-IR spectrum of L, assigned to the azomethine linkage of L. This band shifted to the higher wave number in the polychelate. Inaddition, a new sharp band is seen at 814 cm-1, related to the V=O stretching vibrations. These observations indicating the coordination of the ligand to metal ion.The 1 H-NMR spectrum of the L confirmed the functional groups of L. It exhibits resonance signals at 10 ppm, 7-9 ppm and 11 ppm which is assigned to the CH=N, groups, aromatic protons and –OH groups, respectively