Abstract: | PrIII and three synthesized ligands, 8-hydroxyquinoline-2-carboxaldehyde-(benzoyl)hydrazone, 8-hydroxyquinoline-2-carboxaldehyde-(2′-hydroxybenzoyl)hydrazone, and 8-hydroxyquinoline-2-carboxaldehyde-(isonicotinyl)hydrazone, respectively, can form binuclear PrIII complexes with 1?:?1 metal-to-ligand stoichiometry and nine-coordination at PrIII indicated by X-ray crystal structural analyses. Ligands are dibasic tetradentate, binding to PrIII through the phenolate oxygen, nitrogen of quinolinato unit, the C=N of methylene, and –O–C=N– enolized and deprotonated from O=C–NH– of the aroylhydrazone side chain. One DMF binds orthogonally to the ligand plane from one side to the metal ion, while another DMF and a bidentate nitrate simultaneously bind from the other. Dimerization of the monomeric unit occurs through the phenolate oxygen leading to a central planar four-membered (PrO)2 ring. The crystal structures are similar to each other and to other nine-coordinate lanthanide complexes with geometry of distorted edge-sharing mono-capped square-antiprism of LnL(NO3)(DMF)2]2 (Ln = LaIII, NdIII, SmIII, EuIII, TbIII, DyIII, HoIII, and ErIII) except for YbIII with eight-coordinate YbIII center with distorted edge-sharing dodecahedron of YbL(NO3)(DMF)]2, derived from 8-hydroxyquinoline-2-carboxaldehyde and aroylhydrazines. The ligands and PrIII complexes can bind to calf thymus DNA through intercalation with binding constants at 105 M?1 and probably be used as potential antitumor drugs. |