Glucose-lowering Activity of Amino Acid-N-phosphonic Acid Oxovanadium Complexes and Its Interaction with DNA

Vanadium has well-documented lowering glucose properties both in vitro and in vivo.The design of newoxovanadium(IV) coordination compounds,intended for use as insulin-enhancing agents in the treatment of diabe-tes mellitus,can potentially benefit from a synergistic approach,in which the whole complex has more than an ad-ditive effect from its component parts.Biological testing with oxovanadium(IV) organic phosphonic acid,for insu-lin-enhancing potential included acute administration,by oral garage in streptozotocin (STZ) diabetic rats.Thecomplexes of oxovanadium(IV) amino acid-N-phosphonic acid exhibit higher lowering glucose activity in vivo.Theinteraction of the complexes of oxovanadium(IV) amino acid-N-phosphonic acid with DNA was investigated byagarose gel electrophoresis.The results indicated that these complexes have strong interaction with DNA.     

Glucose-lowering A ivity of Amino Acid- phosphonic Acid Oxovanadium Complexes and Its Interaction with DNA

Vanadium has well-documented lowering glucose properties both in vitro and in vivo. The design of new oxovanadium（IV） coordination compounds, intended for use as insulin-enhancing agents in the treatment of diabetes mellitus, can potentially benefit from a synergistic approach, in which the whole complex has more than an additive effect from its component parts. Biological testing with oxovanadium（IV） organic phosphonic acid, for insulin-enhancing potential included acute administration, by oral gavage in streptozotocin （STZ） diabetic rats. The complexes of oxovanadium（IV） amino acid-N-phosphonic acid exhibit higher lowering glucose activity in vivo. The interaction of the complexes of oxovanadium（IV） amino acid-N-phosphonic acid with DNA was investigated by agarose gel electrophoresis. The results indicated that these complexes have strong interaction with DNA.     

Synthesis, characterization and magnetic properties of μ-iodanilato dinuclear oxovanadium (Ⅳ) complexes

Five oxovanadium(Ⅳ) dinuclear complexes described by the overall formula [(VO)2(IA)L2]-SO4, where IA represents the dianion of iodanilic acid and L denotes 2,2'-bipyridine (bpy) ; 4,4'-dimethyl-2,2'-bipyridine (Me2-bpy); 1,10-phenanthroline (phen); 4,7-diphenyl-1, 10-phenanthroline (Ph2-phen) and 5-nitro-l, 10-phenanthroline (NO2-phen) , have been synthesized and characterized by elemental analyses, molar conductivity and room-temperature magnetic moment measurements, IR and electronic spectral studies. It is proposed that these complexes have IA-bridged structures and consist of two oxovanadium(Ⅳ) ions each in a square- pyramidal environment. The complexes [ ( VO)2 (IA) (bpy )2 ] SO4 (1) and [ ( VO )2 ( IA) ( phen)2 ] -SO4 (2) were further characterized by variable temperature (4.2-300 K) magnetic susceptibility measurements and the observed data were fitted to the modified Bleaney-Bowers equation by the least-squares method, giving the exchange integral J = -2.15 cm-1 for 1 and J = - 9.88 cm-1 for 2     

Synthesis of 7,7’-Disubstituted BINAP and Their Application in Asymmetric Catalytic Reaction

The design of new chiral ligands plays a very important role in the development of transition metal catalyzed asymmetric synthesis. Many chiral diphosphine ligands have been prepared and applied in asymmetric catalytic reactions with excellent enantioselectivities. Among the chiral diphosphine ligands reported, BINAP was found to have been the widest application in the transition metal catalyzed reaction. Recently we have developed a novel oxovanadium (Ⅳ) complex catalyst for the oxidative …     

Investigation of the Crystallization Kinetics of Zn(Met)(AcO)_2·H_2O in Mixed Solution of Water and Acetone by Microcalorimetry

Introduction The complexes of zinc salts with -amino acid as additive have a wide application in medicine, foodstuff and cosmetics.1-3 The synthesis methods of the com-plexes of zinc salts with -amino acid have been re-viewed.4 The solubility of Zn(AcO)2-Met-H2O system at 298.15 K has ever been investigated by the semi-micro-phase equilibrium method.5 The phase diagram is a simple one, in which the solid complex of Zn(AcO)2 and Met can not be obtained at 298.15 K. Zn(Met)2+ in solution w…     

Syntheses and Crystal Structures of Lanthanide Complexes of New 15-Membered Macrocyclic Ligands with Three Pendant Acetato Groups

Two new 15-memhored fimctionalized macrocycles, dioxo-polyazacydoalkanes with three pendant acetato groups, have been synthesized by the condensation reaction of DTPA dianhy-dride (DTPA = diethylenetrlamlnepentaacetic acid ) with 1,2-di-amlnopropane, ( 15-DTPA-1, 2-pn), or 1, 2-diaminocydohex-ane, (15-DTPA-1,2-cy). Their lanthanide complexes [ Ln ( 15-DTPA-1,2-pn)(H2O)]2[Ln= Eu (1), Gd (2)] and [Ln(15-DTPA-1,2-cy)(H2O)]2[Ln= Eu (3), Gd (4)] were also pre-pared. Single crystal X-ray diffraction analyses of complexes 2 and 4 show that they have dimeric structures in solid state;each metal ion is nine-coordinated in a distorted tricapped-trig-onal prism. In complex 4, the coexistence of two diastereoiso-meric molecules in the crystal lattice was observed.     

Coordination behavior of N-benzoylamino acids: Synthesis and structure of mixed-ligand complexes of palladium(Ⅱ) with N-benzoylamino acid dianion and diamine

Four new mixed-ligand complexes of pailadiumt(Ⅱ) with L1(N-benzoyl-α-amino acid dianion) and L2[ethyldiamine (en),2,2'-bipyridine (Bpy) and 1,10-phenanthroline (Phen)] were synthesized.Ail the complexes have been characterized by elemental analyses,molar conductance,infrared and 1H NMR spectra and therme-gravimetric analyses.Crystal structures of [Pd(Bpy)(Bzval-N,O)] and [Pd(en) (Bzphe-N,O)] H2O have been do termmed by X-ray diffraction analysis.The results indicate that in all the complexes hgand L1 coordinates to palladium (Ⅱ) through deprotonated amide nitrogen and carboxylic oxygen,and there are some intramolecular nonrovalent in teractions in the complexes.     

Two New Copper(Ⅱ) Complexes with p-Cyanobenzoic Acid: Synthesis,Crystal Structures and Properties

The complexes of [Cu(bpy)(H2O)(CBA)2]n 1 and [Cu(phen)(H2O)(CBA)2]·H2O 2 based on p-cyanobenzoic acid(HCBA) have been synthesized in aqueous ethanolic solution at room temperature. The single-crystal X-ray diffraction studies demonstrated that complex 1 crystallizes in orthorhombic and complex 2 is of triclinic system. The results indicate the complex 1 shows a 1D chain structure bridged by two carboxylic oxygen atoms from CBA–, and complex 2 is a mononuclear structure. Through intermolecular hydrogen bonding and π...π stacking interactions, the complexes are assembled into supramolecular structures. Complex 1 has been characterized by magnetic measurements. The magnetic measurement indicates that weak ferromagnetic interaction(zJ= 0.038(5)) between the Cu2+ ions is dominant in the structure. The IR spectrum and results of thermal and elemental analyses are also presented.     

Antituberculosis and cytotoxic activities of triorganotin(Ⅳ) complexes

Five triorganotin（Ⅳ）（1-5） complexes of cinnamic acid.（Z）-2-acetamido-3-phenylacrylic acid,3-methylbut-2-enoic acid,and 2,2-diphenylacetic acid have been synthesized and characterized by ¹H-¹³C-¹¹⁹Sn NMR,UV,and IR.The spectroscopic investigation demonstrated that the carboxylate group acts as a monodentate ligand in triorganotin（IV） compounds.Five triorganotin（Ⅳ） complexes were screened against the log phase culture of Mycobacterium tuberculosis H37Rv by colorimetric method using XTT dye as growth indicator.The MICs were found to be 0.08 and 1.25μg/mL.     

Synthesis, Crystal Structure, UV-vis and EPR Studies of（ NH3CH2CH2NH2 ） 2.5 [ Mo0.5^（V）W0.5^（VI）O2 （ OC6H4O ） 2]

Cis-dioxo-metal complex ( NH3CH2CH2NH2 ) 2.5 [ Mo0.5^(V)W0.5^(VI)O2 ( OC6H4O ) 2] 1 was obtained by the reaction of tetra-butyl ammonium hexamolybdotungstate with 1, 2-dihydroxybenzene in the mixed solvent of CH3OH, CH3CN and ethylenediamine,and characterized by X-ray diffraction, UV-vis and EPR analysis. Compared with its analogous complexes (NH3CH2CH2NH2)3[Mo^(V)O2(OC6H40)2] 2 and (NH3CH2CH2NH2)2[W^(VI)O2(OC6H4O)2] 3, the results show that tungsten(VI) is less active in redox than molybdenum (VI) and that the change of the valence induced by substitution of W(VI) for Mo(V) in EMO2(OC6H40)2]n- does not influence the coordination geometry of the complex anion in which the metal center exhibits distorted octahedral coordination with cis-dioxo catechol. The responses to EPR of complexes 1 and 2 are active but complex 3 is silent,and the UV-vis spectra exhibited by the three complexes are obvious different because of the different electronic configuration between the central Mo(V) and W(VI) ions in the complexes.It is noteworthy that complexes 1 and 2 have the similar EPR signal to flavoenzyme, suggesting that the three complexes have the same coordination geometry feature with the co-factor of flavoenzyme.     

A study on the glucose lowering effects of ester-based oxovanadium complexes

The ester-based vanadium complexes, bis(methylacetoacetato) oxovanadium (IV), bis(ethylacetoacetato) oxovanadium(IV) and bis(ethylbenzoylacetato) oxovanadium(IV), have been prepared and characterized by physicochemical and spectroscopic methods. The biological efficacies of the complexes were investigated. These complexes possess substantial glucose lowering ability and also show improved glucose tolerance effect.     

Synthesis,characterization and oxidase catalytic activity of vanadium(IV) and oxovanadium(IV) complexes with Schiff base ligands derived from β-diketones

New complexes of vanadium(IV) and oxovanadium(IV) with Schiff base ligands derived from -diketones and ethanolamine or o-aminophenol have been prepared and characterized by elemental analyses, electrical conductance, magnetic moment measurements, and by i.r., u.v.–vis. and e.p.r. spectroscopy. A distorted octahedral environment was proposed for the vanadium(IV) and oxovanadium(IV) complexes. The spectroscopic results were utilized to compute the important ligand field parameters. Three adduct complexes were isolated owing to the interaction of one oxovanadium complex with Lewis-bases in MeOH. Vanadium(IV) complexes exhibit promising catalytic activity towards the aerobic oxidation of p-phenylenediamine (PPD) to the corresponding semi-oxidized form (PPD⁺). A linear correlation exists between the oxidase catalytic activity and the Lewis acidity of the central vanadium(IV) ion created by the donating properties of the parent ligand.     

Synthesis and mesomorphic properties of some platinum(II) and oxovanadium(IV) complexes

The synthesis and mesomorphic properties of a homologous series of N-(2-hydroxy-4-n-alkoxybenzylidene)-4'-n-decylphenylanilines and their platinum(II) and oxovanadium(IV) complexes are reported. All the ligands and their metal chelates exhibit enantiotropic mesophases, predominantly smectic A and smectic C phases. The transition temperatures and enthalpies have been determined for most of the compounds. The platinum(II) complexes have higher melting points and mesophase thermal stabilities. However, the oxovanadium(IV) complexes have a wider thermal range for the mesophase. Both platinum(II) and oxovanadium(IV) complexes containing only a chain on the biphenyl moiety exhibit a nematic phase.     

Mononuclear oxovanadium complexes of tris(2-pyridylmethyl)amine

Mononuclear oxovanadium(IV) and dioxovanadium(V) complexes of tris(2-pyridylmethyl)amine (tpa) have been prepared for the first time. Crystal structure determinations of three oxovanadium(IV) complexes, [VO(SO4)(tpa)], [VOCl(tpa)]PF6, or [VOBr(tpa)]PF6, and a dioxovanadium(v) complex [V(O)2(tpa)]PF6 disclosed that the tertiary nitrogen of the tpa ligand always occupies the trans-to-oxo site. The structures of an oxo-peroxo complex [VO(O2)(tpa)]Cl that was prepared previously and of a mu-oxo vanadium(III) complex [{VCl(tpa)}2(mu-O)](PF6)2 have also been determined. The tertiary nitrogen is located at a trans site to the peroxo and chloride ligands, respectively. The total sums of the four V-N bond lengths from the tpa ligand are remarkably similar among the six complexes, indicating that the vanadium oxidation states become less influential in tpa bonding due primarily to the coordination of electron-donating oxo ligand(s). Absorption spectra of [VOCl(tpa)]+ in acetonitrile showed a significant change upon addition of p-toluenesulfonic acid and HClO4, but not on addition of benzoic acid. Protonation at the oxo ligand by the former two acids is suggested. Cyclic voltammetric studies in acetonitrile verified the proton-coupled redox behavior of the V(III)/V(IV) process involving the oxo ligand for the first time. From the dependence of the added p-toluenesulfonic acid to the CV, redox potentials for the following species have been estimated: [V(IV)OCl(tpa)]+/[V(III)OCl(tpa)](E1/2=-1.59 V vs. Fc+/Fc), [V(IV)(OH)Cl(tpa)]2+/[V(III)(OH)Cl(tpa)]+(Epc=-1.34 V), [V(IV)(OH2)Cl(tpa)]3+/[V(III)(OH2)Cl(tpa)]2+(Epa=-0.49 V), and [V(IV)Cl2(tpa)]2+/[V(III)Cl2(tpa)]+(E1/2=-0.89 V). The reduction of [V(V)(O)2(tpa)]+ in 0.05 M [(n-Bu)4N]PF6 acetonitrile showed a major irreversible reduction wave V(V)/(IV) at -1.48 V. The metal reduction potentials of the oxovanadium(IV) and dioxovanadium(V) species are very close, reinforcing the significant influence of the oxo ligand(s).     

Bestimmung des Oxydationszustandes in Vanadiumkomplexen mit Hilfe von V—K-Röntgenabsorptionsspektren

Determination of the Oxydation State in Vanadium Complexes using V—K-Absorption Spectra The compounds resulting from the reaction of oxovanadium(IV) sulfate with 8-quinolinols in air were characterized by magnetic moments and V—K-absorption spectra. 8-quinolinol and its Mannich derivates (“CMAB-oxine”, “CMAP-oxine”) form vanadium(V) complexes. The oxovanadium(IV) compound of 7-methyl-8-quinolinol initially formed is not very stable in solution and tends to oxydation. Only the oxovanadium(IV) complex of 2-methyl-8-quinolinol has a good stability corresponding to that of β-diketone compounds.     

Structural models of vanadate-dependent haloperoxidases and their reactivity

Vanadium(V) complexes with hydrazone-based ONO and ONN donor ligands that partly model active-site structures of vanadate-dependent haloperoxidases have been reported. On reaction with [VO(acac)₂] (Hacac = acetylacetone) under nitrogen, these ligands generally provide oxovanadium(IV) complexes [VO(ONO)X] (X = solvent or nothing) and [VO(acac)(ONN)], respectively. Under aerobic conditions, these oxovanadium(IV) species undergo oxidation to give oxovanadium(V), dioxovanadium (V) or μ-oxobisoxovanadium(V) species depending upon the nature of the ligand. Anionic and neutral dioxovanadium(V) complexes slowly deoxygenate in methanol to give monooxo complexes [VO(OMe)(MeOH)(ONO)]. The anionic complexes [VO₂(ONO)]^- can also be convertedin situ on acidification to oxohydroxo complexes [VO(OH)(HONO)]⁺ and to peroxo complexes [VO(O₂)(ONO)]^-, and thus to the species assumed to be intermediates in the haloperoxidases activity of the enzymes. In the presence of catechol (H₂cat) and benzohydroxamic acid (H₂bha), oxovanadium (IV) complexes, [VO (acac)(ONN)] gave mixed-chelate oxovanadium(V) complexes [VO(cat)(ONN)] and [VO(bha)(ONN)] respectively. These complexes are not very stable in solution and slowly convert to the corresponding dioxo species [VO₂(ONN)] as observed by⁵¹V NMR and electronic absorption spectroscopic studies.     

Synthesis, ab initio calculations, thermal, thermodynamic and antioxidant properties of some oxovanadium(IV) complexes containing N2O2 set of donor atoms

The formation constants of some oxovanadium(IV) binary complexes containing Schiff bases resulting from condensation of salicylaldehyde with aniline and with its derivatives were determined spectophotometrically. The synthesized compounds were characterized by analytical and different physico-chemical techniques like ¹H NMR, IR, elemental analysis, mass and UV-Vis spectral studies. The IR spectra affirm that coordination takes place through azomethine nitrogen and phenolate oxygen. Three of the VO(IV) Schiff base complexes i.e. bis(salicylideneaniline)oxovanadium(IV), [VO(L¹)₂], bis(salicylidene-4-methoxyaniline) oxovanadium (IV), [VO(L²)₂] and bis(salicylidene-4-cyanoaniline)oxovanadium(IV), [VO(L¹⁰)₂], were studied by thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathways. The number of steps and, in particular, the starting temperature of decomposition of these complexes depends on the equatorial ligand. The complexes screened for antioxidant activity and the ab initio calculations were carried out to determine the structural and the geometrical properties of a typical vanadyl salicylideneaniline complex, [VO(L¹)₂].     

Template synthesis and characterization of oxovanadium(IV) complexes with tetraaza macrocyclic ligands and their activity on potato virus X

The oxovanadium(IV) complexes (I) of the type [VO(L)]SO₄ have been prepared using an in-situ method of synthesis with ligands derived from di-2-thienylethanedione with 1,2-diaminobenzene or 2,3-diaminopyridine. These parent complexes have been further reacted with μ-diketones to yield macrocyclic complexes (II) of types [VO(mac)]SO₄ (where mac = macrocyclic ligands derived by condensation of amino group of parent complex with μ-diketones), wherein the VO²⁺ cation acts as a template. Tentative structures of these complexes have been proposed on the basis of elemental analysis, electrical conductance, magnetic moments and spectral (infrared, electronic and electron spin resonance) data. The oxovanadium(IV) complexes are five coordinated wherein the tetraaza macrocyclic ligands act as tetradentate chelating agents. All the complexes are found to inhibit the infectivity of potato virus X, when checked using the test plant Chenopodium amaranticolor.