Near-infrared surface-enhanced Raman scattering of a kind of self-assemblies film based on coordination bond

Near-infrared surface-enhanced Raman spectroscopy was applied to the investigation of 4,4′-bipyridine, 4,4′-azopyridine, bissalicylaldehydeethylenediimine Co(II) and Ni(II) (abbreviated as Salen-Co and Salen-Ni, respectively) as mono- and alternating multi-layer self-assembly films deposited onto the roughened silver foil substrate. 4,4′-Bipyridine, 4,4′-azopyridine can be adsorbed onto the silver substrate through the interaction of N-atom of the pyridine ring via metal surface. The orientation of molecular long axis for both molecules are normal to the surface of the substrate. The alternating films can be obtained by the coordinate interaction between the pyridine and the metal chelates of Salen-Co and Salen-Ni. The plane of the metal chelates are parallel to the surface of silver substrate.