DFT and ~1HNMR molecular spectroscopic studies onbiologically anti-oxidant active paramagneticlanthanide(III)-chrysin complexes

摘要

The interaction of trivalent lanthanide chlorides and chrysin in methanol results in formationof the complexes [Ln(chrysin)_3], where Ln = La, Pr, Nd, Sm, Gd, Tb and Ho. The complexeshave been characterized by elemental analyses, molar conductance, IR, UV–Vis, TGA/DTAand NMR spectroscopic studies. They behave as non-electrolytes in DMF solution. The TGAdata indicated that the complexes were anhydrous. The electronic spectra of the complexeswere recorded in methanol DMF and DMSO solutions. ~1H NMR spectra of lanthanum,praseodymium, neodymium, samarium and gadolinium complexes have been studied inDMSO-d_6.~ 1HNMR spectra of paramagnetic and diamagnetic complexes exhibit down-field aswell as up-field shifts of chrysin resonances that shows a change in geometry during the ligandcoordination to the metal ion. A theoretical study of the chrysin molecule was conductedthrough DFT, ab initio, and AM1 methods and this determined the coordination environmentof the metal ions.