Featured Properties of the Adsorption of Tebuconazole on Ag Surface Characterized through SERS Spectroscopy

Abstract

Pesticides present utmost importance in modern agriculture and are extensively used in countries with strong agricultural activity, such as Brazil. However, these substances are considered a significant part of environmental contamination by organic compounds. In the present work, Raman spectroscopy was employed in the vibrational characterization of the fungicide tebuconazole and surface-enhanced Raman scattering spectroscopy to the study of the adsorption of this compound on the surface of Ag nanoparticles. The proposed chemical interaction between tebuconazole and the metallic surface was inferred by relating experimental results and vibrational assignment supported by density functional theory calculations. The vibrational assignments of surface-enhanced Raman scattering spectra, by considering surface selection rules, suggest that the adsorption of the tebuconazole with Ag surface occurs by interactions of phenyl and triazole groups simultaneously. For the case of the interaction with the phenyl group, a modification of the charge distribution in the ring after adsorption was hypothesized, which was supported through the analysis of the frontier molecular orbitals of the Ag-tebuconazole complex calculated by density functional theory.