title: Adsorption of benzoic acid, phthalic acid on gold substrates studied by surface-enhanced Raman scattering spectroscopy and density functional theory calculations.
abstract: Benzoic acid (BA) and phthalic acid (PTA) are the simplest aromatic carboxylic acids, and they can be regarded as typical model compounds in investigating the interaction of aromatic carboxylic acids with metal surfaces by use of SERS spectroscopy. In this work, we have investigated the structure and adsorption behavior of benzoic acid and phthalic acid on the gold surface with combination of SERS and DFT calculation methods. The experimental results show that both BA and PTA may be adsorbed on the Au surface with a bidentate bridging structure, namely, the carboxylate group(s) being bound to gold via two oxygen atoms in the carboxylate group(s). Comparison of the observed SERS and predicted spectra of the complexes of these two substances with Au atoms indicates that BA is favorable to adsorb on the gold surface with a vertical orientation rather than a flat one, and PTA could "stand up" on the Au surface as a slight tilt with a two-legged geometry, i.e. all four oxygen atoms in two carboxylate groups interact on the metal surface. Apart from that, we compare the discrepancy of SERS spectra between those two molecules, which could be taken as a potential analysis technique in food safety field.
authors.affiliation: MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Gao
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Hu
authors.forename: Shaoxin
authors.initials: S
authors.lastname: Li
authors.forename: Yanjiao
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xue
authors.initials: X
authors.lastname: Chen
mesh_terms: D000327:Adsorption; D019817:Benzoic Acid / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010795:Phthalic Acids / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D010795:Phthalic Acids; D012996:Solutions; C032279:phthalic acid; D006046:Gold; D019817:Benzoic Acid