Understanding the Equilibria of Thio Compounds Adsorbed on Gold by Surface-Enhanced Raman Scattering and Density Functional Theory Calculations

Author(s)

Paulo, Tercio de F. ^[1] ; Ando, Romulo A. ^[1] ; Diogenes, Izaura C. N. ^[2] ; Temperini, Marica L. A. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, BR-05508000 Sao Paulo - Brazil

^[2] Univ Fed Ceara, Dept Quim Organ & Inorgan, BR-60455970 Fortaleza, Ceara - Brazil

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 117, n. 12, p. 6275-6283, MAR 28 2013.
• Web of Science Citations: 12

Abstract

The self-assembled monolayers (SAMs) derived from thionicotinamide (TNA), thioisonicotinamide (iTNA), and 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol (Hpyt) on gold have been characterized via surface-enhanced Raman scattering (SEAS) as a function of pH and applied potential. Density functional theory calculations performed on the molecule/metal interaction model reinforced the vibrational assignments of the SERS spectra. Despite the structural similarity, these compounds presented different behaviors depending on the pH and applied potential with the iTNA SAM being the most affected. Upon adsorption and at pH 6, Hpyt SAM is not protonated while TNA and iTNA SAMs are partially and completely protonated, respectively. The results presented herein, besides being helpful for the understanding of the formation of the SAMs, can shed light on the understanding of the different responses observed for the cytochrome c metalloprotein by using the SAMs derived from these molecules. (AU)

• FAPESP's process: 11/12479-3 - SELF-ASSEMBLED MONOLAYERS OF SULFUR COMPOUNDS: A SPECTROSCOPY STUDY
• Grantee: Tercio de Freitas Paulo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral