Raman, FT-IR and DFT studies of ortho-, meta- and para-pyridinomethylene substituted di(4-hydroxy-coumarin) and their Ce(III), La(III) and Nd(III) complexes

✍ Scribed by I. Georgieva; I. Kostova; N. Trendafilova; V. K. Rastogi; G. Bauer; W. Kiefer

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 259 KB
• Volume: 37
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/jrs.1504

✦ Synopsis

Abstract

Vibrational spectra of ortho‐, meta‐ and para‐pyridinomethylene substituted di(4‐hydroxycoumarin) (o‐, m‐, p‐PyDC, (PyDCs)) and their Ce(III), La(III) and Nd(III) complexes were studied by Raman and Fourier transform infrared (FT‐IR) spectroscopies. Density functional theory (DFT) at B3LYP/6‐31G(d) level was used to determine the geometrical and vibrational characteristics of the neutral PyDC isomers and their dianionic forms. The experimental IR and Raman bands of PyDCs were assigned to the corresponding normal modes on the basis of DFT calculations. The effect of the intramolecular H‐bonds in PyDCs as well as of the PyDCs deprotonation on the vibrational mode positions was estimated by comparison with the molecular vibrations of the H‐bonding‐free 4‐hydroxycoumarin and PyDC dianionic forms. The characteristic IR and Raman bands of o‐, m‐ and p‐PyDC were specified and discussed. The comparative vibrational analysis of the neutral and the dianionic PyDCs and their Ln(III) complexes gave evidence that the PyDC ligands bound the lanthanide(III) through the carbonylic oxygens and the deprotonated hydroxylic oxygens. Copyright © 2006 John Wiley & Sons, Ltd.