Crystal structures, antioxidation and DNA binding properties of Yb(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carbaldehyde and four aroylhydrazines

Structural and vibrational study of 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone--a potential metal-protein attenuating compound (MPAC) for the treatment of Alzheimer's disease

A comprehensive structural and vibrational study of the potential metal-protein attenuating compound 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone is reported. X-ray diffraction data, as well as FT-IR and Raman frequencies, were compared with the respective theoretical values obtained from DFT calculations. Theory agrees well with experiment. In this context, an attempt of total assignment concerning the FT-IR and Raman spectra of the title compound was performed, shedding new light on previous partial assignments published elsewhere.

Antioxidation and DNA-binding properties of binuclear lanthanide(III) complexes with a Schiff base ligand derived from 8-hydroxyquinoline-7-carboxaldehyde and benzoylhydrazine

8-Hydroxyquinoline-7-carboxaldehyde (8-HQ-7-CA), Schiff-base ligand 8-hydroxyquinoline-7-carboxaldehyde benzoylhydrazone, and binuclear complexes [LnL(NO(3))(H(2)O)(2)](2) were prepared from the ligand and equivalent molar amounts of Ln(NO(3))·6H(2)O (Ln=La(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Dy(3+), Ho(3+), Er(3+), Yb(3+), resp.). Ligand acts as dibasic tetradentates, binding to Ln(III) through the phenolate O-atom, N-atom of quinolinato unit, and C=N and -O-C=N- groups of the benzoylhydrazine side chain. Dimerization of this monomeric unit occurs through the phenolate O-atoms leading to a central four-membered (LnO)(2) ring. Ligand and all of the Ln(III) complexes can strongly bind to CT-DNA through intercalation with the binding constants at 10(5)-10(6) M(-1). Moreover, ligand and all of the Ln(III) complexes have strong abilities of scavenging effects for hydroxyl (HO·) radicals. Both the antioxidation and DNA-binding properties of Ln(III) complexes are much better than that of ligand.

Fluorescent and ultraviolet-visible spectroscopy studies on the antioxidation and DNA binding properties of binuclear Tb(III) complexes

Tb(III) complexes were prepared from Tb(NO(3))(3)·6H(2)O and four Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde with aroylhydrazines. X-ray crystal and other structural analyses indicate that Tb(III) and every ligand can form a binuclear Tb(III) complex with 1:1 metal-to-ligand stoichiometry and nine-coordination at the Tb(III) center. Viscosity titration experiments and fluorescent and ultraviolet-visible (UV-Vis) spectroscopy results indicate that all the Tb(III) complexes can bind to Calf thymus DNA through intercalation with the binding constants at the order of magnitude of 10(6)-10(7) M(-1), and they may be used as potential anticancer drugs, but complexes containing active phenolic hydroxy groups may have stronger antitumor activities. Antioxidation results indicate that all the Tb(III) complexes have strong abilities of scavenging hydroxyl radicals and superoxide radicals, but complexes containing active phenolic hydroxy groups show stronger scavenging effects on hydroxyl radicals and complexes containing N-heteroaromatic substituent show stronger scavenging effects on superoxide radicals. However, Tb(III) emission with these systems is not observed, for these ligands rather are quenchers and unable to sensitize this metal ion.

Antioxidation and DNA-binding properties of binuclear Er(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde and four aroylhydrazines

The Er(III) complexes are prepared from Er(NO(3))(3).6H(2)O and Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde with four aroylhydrazines, including benzoylhydrazine, 2-hydroxybenzoylhydrazine, 4-hydroxybenzoylhydrazine and isonicotinylhydrazine, respectively. X-ray crystal and other structural analyses indicate that Er(III) and every ligand can form a binuclear Er(III) complex with nine-coordination and 1: 1 metal-to-ligand stoichiometry at the Er(III) centre. All the Er(III) complexes can bind to calf thymus DNA through intercalation with the binding constants at the order of magnitude 10(6) M(-1), and they may be used as potential anticancer drugs. All the Er(III) complexes have strong scavenging effects for hydroxyl radicals and superoxide radicals; however, complex containing active phenolic hydroxyl group shows stronger scavenging effects for hydroxyl radicals and complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radicals.