¹H NMR, spectroscopic and molecular modeling studies on paramagnetic lanthanide(III)-quercetin complexes

Article type: Research Article

Authors: | Ansari,

Affiliations: National Physical Laboratory, Dr K. S. Krtishanan Marge, New Delhi 110012

Note: [] Corresponding author. E-mail: [email protected]

Abstract: Nine coordinated [Ln(quercetin)3]nH2O complexes were synthesized in non-aqueous solution (where, n = 0 for Pr, Sm, Gd, Tb, Dy and Ho; n = 3, for La and Nd). The complexes were characterized by elemental analysis, molar conductance, UV – vis spectra, IR spectra, thermal analysis and NMR spectra. The optimized structures of the complexes were obtained by molecular modeling. The complexes behave as non-electrolytes in DMSO. TGA study showed anhydrous nature of the complexes (except La and Nd). The 1H NMR spectra of lanthanum, praseodymium, neodymium and samarium complexes have been studied in DMSO-d6. The complexes do not dissociate in DMSO and retain their coordination number. The NMR spectra of paramagnetic and diamagnetic complexes of quercetin exhibit lower as well as higher field shifts that show change in geometry during the metal ligand coordination.

Keywords: Quercetin, Lanthanides, Molecular modeling, Density functional theory, 1H NMR

DOI: 10.1080/10241220801890072

Journal: Main Group Chemistry, vol. 7, no. 1, pp. 15-30, 2008