Raman and SERS study on cimetidine-metal complexes with biomedical interest

Sergio Bonora, Michele Di Foggia, Vitaliano Tugnoli, Valeria Righi, Enrico Benassi, Assimo Maris

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Cimetidine (cim) is one of the most potent histamine H2-receptor antagonists for inhibiting excessive acid secretion caused by histamine; it has been hypothesized that the therapeutic effects can be related to its interactions with metal ions. Raman spectra of the solid cim with Co(II), Cu(II), Ni(II) and Zn(II) metal complexes show that they can adopt two different structures: one is octahedral and the other, with Zn(II), is probably tetrahedral. The octahedral structure appears to be distorted both by the different metal ions as well as by the different anion present. The study was extended to very dilute solutions (ppm range) by using the surface-enhanced Raman scattering (SERS) technique, mimicking the physiological concentrations of cim and its metal complexes. SERS spectra suggest that, upon the binding of cim to silver colloids, the formation of stable 1:2 cim-metal complexes is excluded, the formation of 1:1 adduct appearing more probable; in this product the metal reaches its total coordination shell by complexion with water molecules. To better explain the binding mechanism of cim to a metal (Ag) surface, we performed theoretical B3LYP calculations on cim alone as well as on cim bonded to an Ag2 metal cluster in presence of water, observing a sufficiently good agreement between experimental and theoretical wavenumbers. Raman spectra of the solid cimetidine (cim) 2:1 metal complexes with Co(II), Cu(II), Ni(II) and Zn(II) were studied, which showed the existence of two different structures. The study was extended in the very dilute solutions by using the SERS technique, which suggested that, upon the binding to silver colloids, the formation of 1:1 cim-metal adduct was preferred for any metal. Theoretical B3LYP calculation on cim bonded to an Ag2 metal cluster in presence of water was performed.

Original languageEnglish
Pages (from-to)612-620
Number of pages9
JournalJournal of Raman Spectroscopy
Volume42
Issue number4
DOIs
Publication statusPublished - 1 Apr 2011
Externally publishedYes

Keywords

  • cimetidine
  • CPCM calculation
  • metal complex
  • Raman spectroscopy
  • SERS

ASJC Scopus subject areas

  • Materials Science(all)
  • Spectroscopy

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