ABSTRACT
Oxidovanadium(V) complexes, [(+)VOL1-5] and [(-)VOL1-5], with chiral tetradentate Schiff bases, which are products of monocondensation of S(â)-3-amino-1,2-propanediol or R(+)-3-amino-1,2-propanediol with salicylaldehyde derivatives, have been synthesized. Different spectroscopic methods, viz. 1H and 51V NMR, IR, UV-Vis, and circular dichroism, as well as elemental analysis, have been used for their detailed characterization. Furthermore, the epoxidation of styrene, cyclohexene, and two monoterpenes, S(â)-limonene and (â)-α-pinene, using two oxidants, aqueous 30% H2O2 or tert-butyl hydroperoxide (TBHP) in decane, has been studied with catalytic amounts of all complexes. Finally, biological cytotoxicity studies have also been performed with these oxidovanadium(V) compounds for comparison with cis-dioxidomolybdenum(VI) Schiff base complexes with the same chiral ligands, as well as to determine the cytoprotection against the oxidative damage caused by 30% H2O2 in the HT-22 hippocampal neuronal cells in the range of their 10-100 µM concentration.
Subject(s)
Schiff Bases , Schiff Bases/chemistry , Schiff Bases/pharmacology , Schiff Bases/chemical synthesis , Catalysis , Stereoisomerism , Animals , Vanadium/chemistry , Coordination Complexes/chemistry , Coordination Complexes/pharmacology , Coordination Complexes/chemical synthesis , Oxidative Stress/drug effects , Mice , HumansABSTRACT
New oxidovanadium(V) complexes, VOL1-VOL10, with chiral tetradentate Schiff bases obtained by monocondensation reaction of salicylaldehyde derivatives with 1S,2S-(+)-2-amino-1-(4-nitrophenyl)-1,3-propanediol. All complexes have been characterized using different spectroscopic methods, viz. IR, UV-Vis, circular dichroism, one- (1H, 51V) and two-dimensional (COSY, NOESY) NMR spectroscopy, and elemental analysis. Furthermore, the catalytic ability of all compounds in the epoxidation of styrene, cyclohexene, and its naturally occurring monoterpene derivatives, i.e., S(-)-limonene and (-)-α-pinene has also been studied, using two different oxidants, i.e., aqueous 30% H2O2 or tert-butyl hydroperoxide (TBHP). In addition, the biological properties of these chiral oxidovanadium(V) compounds, but also cis-dioxidomolybdenum(VI) complexes with the same chiral Schiff bases, were studied. Their cytotoxic and cytoprotective activity studies with the HT-22 hippocampal neuronal cells revealed a concentration-dependent effect in the range of 10-100 µM. Moreover, vanadium(V) complexes, in contrast to cis-dioxidomolybdenum(VI) compounds, demonstrated higher cytotoxicity and lack of cytoprotective ability against H2O2-induced cytotoxicity.
Subject(s)
Coordination Complexes , Organometallic Compounds , Organometallic Compounds/chemistry , Schiff Bases/pharmacology , Schiff Bases/chemistry , Hydrogen Peroxide , Magnetic Resonance Spectroscopy , Vanadium/chemistry , Coordination Complexes/chemistry , LigandsABSTRACT
In the crystal structure of the title compound, [V(C(12)H(17)N(2)O)O(2)], the vanadium(V) centre is five-coordinate in a distorted square-pyramidal environment. The three atoms of the deprotonated Schiff base and a double-bonded O atom comprise the basal plane. N-Hâ¯O hydrogen bonds lead to a zigzag chain structure parallel to [001].
ABSTRACT
In the crystal structure of the title compound, [V(2)(C(22)H(21)N(2)O(2))(2)O(4)]·2H(2)O, oxide-bridged dimers of the complex are linked to water mol-ecules by hydrogen-bonding inter-actions. The two five-membered chelate rings in the dimeric mol-ecule both adopt twist conformations. Each V(V) atom is six-coordinated by one oxide group and by two N and one O atom of the tridentate Schiff base ligand, and is bridged by two additional oxide atoms. The metal centre has a distorted octa-hedral coordination. The monoanionic ligands occupy one equatorial and two axial positions.
ABSTRACT
In the title dinuclear compound, [V(2)(C(15)H(17)N(2)O)(2)O(4)], each V(V) atom is six-coordinated by one oxide group, and by two N and one O atom of the tridentate Schiff base ligand, and bridged by two additional oxide O atoms, resulting in a centrosymmetric dimer. The metal centre has a distorted octa-hedral coordination with the monoanionic Schiff base ligand occupying one equatorial and two axial coordination positions. The separation between V atoms is 3.214â (3)â Å. In the crystal structure, there are N-Hâ¯O, C-Hâ¯O and C-Hâ¯π hydrogen bonds, and π-π inter-actions.
ABSTRACT
A new monoclinic polymorph of the title compound, [V(2)(C(10)H(13)N(2)O)(2)O(4)], which is a centrosymmetric dimer, crystallizes in space group P2(1)/c, whereas the previously known polymorph crystallizes in the ortho-rhom-bic space group Pbca [Mokry & Carrano (1993 â¶). Inorg. Chem.32, 6119-6121]. Each V(V) atom is six-coordinated by one oxide group, two N atoms and one O atom from the Schiff base ligand, and by two additional bridging O atoms. The two methyl-ene groups are each disordered over two sites, with occupancy factors of 0.776â (14) and 0.224â (14). In the crystal structure, there are C-Hâ¯O hydrogen bonds and C-Hâ¯π inter-actions between the dimers.
ABSTRACT
The title compound, [V(2)(C(13)H(16)N(3)O(3))(2)O(4)]·2C(2)H(6)OS, is a centrosymmetric dimeric complex solvated by two dimethyl sulfoxide mol-ecules. Each V(V) atom is six-coordinated by one oxide group, two N atoms and one O atom from the tridentate Schiff base ligand, and by two additional bridging O atoms in a distorted octa-hedral coordination geometry. Three atoms of the cyclo-hexane ring are each disordered over two sites, with occupancy factors of 0.501â (10) and 0.499â (10). C-Hâ¯O and N-Hâ¯O hydrogen bonds link the dimers and solvent mol-ecules into a supra-molecular network.
