Synthesis, Characterization, Computational Study, and Biological Relevance of a Family of Isostructural, Mononuclear Ln (Ln = Gd, Tb, Dy, Ho, Er) Complexes Containing Pyridoxine, an Essential Ingredient of Vitamin B6 Enzyme

The synthesis and characterization of a family of LnIII complexes (Ln = Gd(1), Tb(2), Dy(3), Ho(4) and Er(5)) of formula [(LnIII(NO3)2(OH2)(pyridoxine)2](NO3) are reported, where pyridoxine is 2-methyl-3-hydroxy-4,5-bis(hydroxymethyl)pyridine. They were obtained from the reaction of Ln(NO3)3 with pyridoxine in ethanol in a 1:1 M ratio. The crystal structures of representative 1 and 5 were obtained using a single-crystal X-ray diffractometer. The subsequent characterization of all the complexes was performed using elemental analysis, IR spectroscopy and UV–Vis spectroscopy. The gadolinium complex was further analyzed to determine if DNA is a biological target of this series of metal complexes. In this regard, the interaction between the gadolinium complex and DNA was probed utilizing circular dichroism spectroscopy. The study supports the moderate binding of complex 1 to DNA