The electrosorption of 3-bromo-2-nitrothiophene on gold as studied with surface-enhanced Raman spectroscopy
The electrosorption of 3-bromo-2-nitrothiophene on a polycrystalline gold electrode has been studied with surface-enhanced Raman spectroscopy SERS. Results imply a tilted orientation of the 3-bromo-2-nitrothiophene molecule with a sulfur atom of the thiophene ring and oxygen atoms of the nitro group interacting directly with the gold surface. The UV-Vis spectrum of the 3-bromo-2-nitrothiophene is recorded and its results indicated that the SERS spectra were measured under off-resonance conditions. Cyclic voltammetry measurements of the 3-bromo-2-nitrothiophene were made and the oxidation and reduction potentials of the 3-bromo-2-nitrothiophene at the gold electrode have been reported. The experimental infrared and Raman data are supported by density functional theory (DFT) calculations of 3-bromo-2-nitrothiophene using the B3LYP level of theory and 6-31G (d) basis set. The vibrational frequencies of the molecule were computed using the optimized geometry obtained from the DFT calculations. The calculated spectra are very close to the recorded infrared and Raman of the solid 3-bromo-2-nitrothiophene. No imaginary frequencies are observed in the calculated spectra. Also, DFT calculations are performed to predict and investigate the adsorption behavior of 3-bromo-2-nitrothiophene on the Au surface. In this DFT calculations,the adsorbed 3-bromo-2-nitrothiophene on the gold electrode surfaces was modeled as the metal-molecule complex.
Synopsis: Electrosorption of 3-bromo-2-nitrothiophene on a polycrystalline gold electrode was discussed. The adsorption orientation and adsorption sites of the 3-bromo-2-nitrothiophene molecule at the gold surface were reported. Electrochemical investigations show a reversible redox behavior in the anodic and cathodic scan direction. The computed frequencies of the 3-bromo-2-nitrothiophene molecule support the results obtained from the recorded IR and Raman spectra.
Volume 133, 2021
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