Spectroscopic and Theoretical Studies of a New Cerium (III) Complex with 3,3′‐(ortho‐Pyridinomethylene)di‐[4‐hydroxycoumarin]

Abstract

A new cerium (III) complex with 3,3′‐(ortho‐pyridinomethylene)di‐[4‐hydroxycoumarin] (o‐PyDC) was synthesized and characterized by various spectroscopic methods: mass spectrometry, ¹H NMR, ¹³C NMR, IR, and Raman spectroscopy. The experimental IR and Raman spectra of o‐PyDC were assigned to the corresponding normal modes on the basis of density functional theory calculations at B3LYP/6‐31G(d) optimized geometry. The NMR, Raman, and IR spectra of the Ce(III) complex were interpreted on the basis of comparison with those of the free ligand. The vibrational analysis and the NMR data give evidence that in the Ce(III) complex, the ligand coordinates with the metal ion through both the deprotonated hydroxyl groups and through the carbonyl groups. The spectroscopic data indicates that the pyridine nitrogen is also involved in coordination with Ce(III). Density functional calculations of a complex fragment structure were performed to elucidate further the binding mode of o‐PyDC to Ce(III) and to explain the NMR and vibrational spectroscopic results.

Keywords:

• Cerium (III) complex
• DFT
• 4‐hydroxycoumarins
• IR spectra
• NMR spectra
• Raman spectra

Acknowledgments

The ligand 3,3′‐(ortho‐pyridinomethylene)di‐[4‐hydroxycoumarin] was synthesized by Dr. I. Manolov and its synthesis was recently published.20

Notes

The authors were invited to contribute this paper to a special issue of the journal entitled “Spectroscopy and Automation”. This special issue was organized by Miguel de la Guardia, Professor of Analytical Chemistry at Valencia University, Spain. The special issue was published in volume 39, issue 6.