Surface enhanced Raman spectroscopy (SERS) and density functional theory (DFT) study for understanding the regioselective adsorption of pyrrolidinone on the surface of silver and gold colloids

The interaction between polyvinyl pyrrolidone (PVP) and the metal atoms on the surface of silver and gold nanoparticles was studied theoretically and experimentally using density function theory (DFT) and surface enhanced Raman spectroscopy (SERS). The attachment of pyrrolidinone and N-methyl-2-pyrrolidinone (monomers of PVP) on the surface gold and silver colloids was probed using the SERS and the band assignments correlated through the DFT quantum chemical calculations. Commonly, the adsorption of N-methyl-2-pyrrolidinone and pyrrolidinone on the surface of silver and gold colloids occurs through the chemisorption of the nitrogen or carboxylic group of the pyrrolidyl ring, with a possible interaction occurring simultaneously via both the nitrogen and carboxylic groups of the ring. SERS experimental investigations and the subsequent DFT theoretical calculations show that both pyrrolidinone and N-methyl-2-pyrrolidinone are selectively adsorbed on silver and gold colloid surfaces preferably via the non-bonding electrons of the carbonyl group.