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Vibrational spectroscopic investigation on the binding modes in Zr(IV) complexes of coumarins

I. KOSTOVA1,* , N. TRENDAFILOVA2, V. K. RASTOGI3, W. KIEFER4

Affiliation

  1. Department of Chemistry, Faculty of Pharmacy, Medical University, 2 Dunav St. Sofia 1000, Bulgaria
  2. Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
  3. Department of Physics, CCS University, Meerut 250 004, India
  4. Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

Abstract

The zirconium(IV) complexes with bis-coumarins: bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-3-yl-methane (m-PyDC) and bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-4-yl-methane (p-PyDC) have been synthesized and characterized. Vibrational study of meta- and para-pyridinomethylene substituted di(4-hydroxycoumarin)s (m- and p- PyDCs) and their Zr(IV) complexes was performed by Fourier transform infrared (FTIR) and Raman (FTR) spectroscopies. Density functional theory (DFT) at B3LYP/6-31G(d) level was used to determine the vibrational characteristics of the neutral PyDCs isomers. The characteristic IR and Raman bands of m- and p-PyDC and their zirconium(IV) complexes were specified and discussed. The vibrational spectral data of zirconium(IV) complexes were interpreted on the basis of comparison with the spectra of the free ligands. These comparative analyses showed that in the Zr(IV) complexes the ligands coordinated to the metal ion through both deprotonated hydroxyl groups and the carbonyl groups.

Keywords

Bis-coumarins, Zirconium(IV) complexes, FTIR and FT-Raman spectra.

Citation

I. KOSTOVA, N. TRENDAFILOVA, V. K. RASTOGI, W. KIEFER, Vibrational spectroscopic investigation on the binding modes in Zr(IV) complexes of coumarins, Optoelectronics and Advanced Materials - Rapid Communications, 1, 10, October 2007, pp.534-542 (2007).

Submitted at: Aug. 6, 2007

Accepted at: Aug. 30, 2007