Spectroscopic and DFT study of atenolol and metoprolol and their copper complexes

IR, Raman and surface-enhanced Raman scattering (SERS) spectra of atenolol (ATE) and metoprolol (MET) were recorded and assigned on the basis of density functional theory (DFT) calculations. A reliable assignment of vibrational IR and Raman bands of the two compounds was possible by a proper choice of models used in quantum chemical calculations. Both molecules are adsorbed to the silver surface mainly through the oxygen atoms and π-electrons of the phenyl ring. The coordination mode of the metal ions in Cu(II)–ATE and –MET compounds was also derived from IR and EPR spectra. EPR spectra give evidence for a square-planar arrangement around the copper (II) ion in the case of Cu–ATE complex, with a N2O2 chromophore. Only oxygen atoms are involved in the cooper coordination for Cu–MET complex, and two types of local symmetries with dx2-y2dx2-y2 and dz2dz2 as ground states for paramagnetic electron coexist.