FT-Raman and FT-IR spectral studies on rare earth complexes with octanedioyl bis(benzo-15-crown-5)

Abstract

Two kinds of complex (A and B) of rare earth nitrates with octanedioyl bis(benzo-15-crown-5) (OBB) were synthesized in this work. the FT-Raman, FT-IR and variable temperature FT-IR (VTFTIR) spectra of complexes A and B have been studied and compared with those of OBB ligand. The spectral differences among the complexes have been observed, especially, the differences of phenyl ring stretching and the CH stretching of phenyl in the FT-Raman spectra and in the bands between 1200 cm −1 and 750 cm −1 in the VTFTIR spectra (298–453K). The remarkable differences in the Raman and IR spectra between OBB ligand and the complexes are in agreement with the results of elemental analysis, which suggest that there a sandwich-like configuration may exist in complex B. Two crown rings of each OBB ligand interact with a Ln(III) ion in complex B, whereas one crown ring of OBB ligand bonds with a Ln(III) ion in complex A. The results show that the combination of FT-Raman and FT-IR spectra is a powerful method for characterizing the fluorescent rare earth complexes.