Synthesis, crystal structures of novel complexes of rare earth with norfloxacin, interaction with DNA and BSA

Three novel rare earth complexes [N(CH3)4][Ln(NF)4]6H2O(Ln=Nd(III)(1), Sm(III)(2), Ho(III)(3)) were synthesized using hydrothermal method from norfloxacin HNF=1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid, C16H18FN3O3), imidazole and rare earth nitrates. The complexes were characterized by elemental analysis, FT-IR, TG-DTG and X-ray single crystal diffraction. Each rare earth ion was eight-coordinated with carboxyl-O atoms and keto-O atoms from norfloxacin. Four of the norfloxacin ions acted as bidentate chelate group took part in the coordination with rare earth ion. The structures of complexes were tetragonal system with space group I41/acd, which were allomerism. The interaction between complex 1 and DNA was studied by electronic absorption spectra and fluorescence spectroscopy. The binding interaction between the complex 1 and bovine serum albumin (BSA) was studied by fluorescence spectroscopy. The complex 1 bound to DNA by the mode of partial intercalation. Complex 1 had a strong ability to quench the fluorescence from BSA. The complex interaction was mainly a static quenching process with BSA together with formation of two binding sites.