XAFS studies of Cu(II) and Co(II) complexes with derivatives of cinnamic acid

Abstract

The metal complexes with the derivatives of the cinnamic acid have been structurally characterized. The geometry of metal-ligand interaction has been determined by X-ray absorption fine structure spectroscopy. The Co(II) complex with 4-methoxycinnamic acid has the octahedral geometry with four carboxylate groups of cinnamate anions and two water molecules in the coordination sphere. Moreover, the Cu(II) complex with 4-nitrocinnamic acid has been synthesized and characterized. In this compound, a square geometry around metal cation is formed by the carboxylate groups from two monodentate ligands and two water molecules.

Investigation of copper oxidation states in plasmonic nanomaterials by XAS and Raman spectroscopy

“…The Cu(I) complex geometry is distorted 35 towards the Cu(II) complex preferred geometry which is either a square planar or an octahedral geometry with an inversion center. 20,21 For copper(II) samples, the profiles are quite similar; only in Cu(II)(bpy)2, the shoulder observed in Cu(I)(phen)2 is present but much weaker. Gaur et al 21 demonstrated that at 8985 eV the edge feature could be assigned to copper(II) square pyramidal complexes.…”

“…XAS spectroscopy is a relevant technique for studying the structure of metal complexes because X-ray absorption near-edge structure (XANES) will give information on the oxidation state of the metal and extended X-Ray absorption fine structure (EXAFS) will provide information on copper's local environment. This technique has been used frequently to describe copper(II) complexes 17,[19][20][21][22][23] but fewer examples of organic copper(I)/complexes have been reported. 24 SERS is a wellestablished technique used for rapid monitoring of molecular and ionic species evolution.…”