Paramagnetic NMR shift, spectroscopic and molecular modeling studies of lanthanide(III)-morin complexes

Studies on nine-coordinate lanthanide complexes of morin are described. The complexes were characterized by elemental analysis, molar conductance, UV-Vis spectra, IR spectra, thermal analysis and NMR spectra. Molecular modeling studies were also carried out. The complexes are non-electrolytes in DMSO. TGA showed anhydrous nature of the complexes. The electronic spectra of the complexes were recorded in methanol. H-1 NMR spectra of lanthanum, praseodymium, neodymium, samarium and dysprosium complexes have been studied in DMSO-d(6). The complexes do not dissociate in DMSO and retain their coordination. H-1 NMR spectra of paramagnetic and diamagnetic complexes exhibit downfield as well as upfield shifts of morin resonances that shows change in geometry during coordination.