SERS and resonance Raman of 5-nitroisatin on silver - The distinction between the coordination and surface complexes

Autor(es)

Marin, Jayr H. ^[1] ; Temperini, Marcia L. A. ^[1] ; Ando, Romulo A. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Lab Espectroscopia Mol, USP, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 263, DEC 15 2021.
• Citações Web of Science: 0

Resumo

Although Surface Enhanced Raman Spectroscopy (SERS) is a widespread technique with applications in several fields, the SERS effect is still not thoroughly understood due to the challenge in describing how the interaction between the analyte and the metallic surface contributes to the Raman signal enhancement. One approach to distinguish the charge transfer contribution from the metal to the molecule is the comparison of the coordination complex resonance Raman spectral features with the SERS spectra of the surface complex excited at different wavelengths. Herein, we investigated the molecule 5-nitroisatin, Nisa, its complex with a silver cation, Ag(Nisa), its anionic form, Nisa, and the adsorbed species over Ag colloid, Nisa/AgNP, by resonance Raman and SERS, respectively. The data show that the resonance Raman spectrum of the coordination complex Ag(Nisa) is comparable to the SERS spectrum obtained out of resonance condition. However, when the SERS spectra of Nisa/AgNP at resonance condition is obtained, quite distinct chromophores are observed. The SERS enhancement profile suggests a charge transfer from the metal to molecule in the green region of the visible spectrum and evidences the higher complexity of the electronic transitions that take place within the surface complex. To support the experimental data, DFT and TDDFT calculations were performed for Nisa, Ag(Nisa), Nisa and Nisa@Ag20 cluster. (C) 2021 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 16/21070-5 - Espectroscopia vibracional com resolução espacial
• Beneficiário: Mauro Carlos Costa Ribeiro
• Modalidade de apoio: Auxílio à Pesquisa - Temático