Dr. M. R. Maurya: Vanadium Chemistry research group in India

Dr. M. R. Maurya
Professor, Inorganic Chemistry
E-mail: rkmanfcy@iitr.ernet.in
Phone: (O): +91 1332 285327 (R): +91 1332 285113
Group web: http://www.iitr.ac.in/~CY/rkmanfcy

 Structural and functional models of vanadate-dependent haloperoxidases.

 Coordination polymers and their catalytic study.

 Metal complexes encapsulated in zeolite cages and their catalytic study.

 Polymer-anchored metal complexes and their catalytic study.

 Medicinal aspects of coordination compounds: Antiamoebic activitiy.

João da Costa Pessoa: Vanadium Chemistry Research Group

João da Costa Pessoa (Associate Professor)

Departamento de Engenharia Química e Biológica

Instituto Superior Técnico

Universidade Técnica de Lisboa (Portugal)

JCP has been involved in projects involving Analytical Chemistry, synthesis of organic compounds, design of molecules for therapeutic use, structural characterization of compounds and catalysis.

Research Interest:

Synthesis: Development of synthetic methodologies for several types of organic compounds by procedures involving activation by metal ions, namely using complexes of vanadium, copper and nickel.

Catalysis: Development of homogeneous and heterogeneous catalytic systems for the synthesis of several types of organic compounds. Asymmetric synthesis involving homogeneous catalysis by transition metal complexes. Synthesis involving catalysts supported in solids, encapsulated in zeolites, or involving adsorbed ionic liquids.

Design of molecules for therapeutic use:

Design, synthesis and characterisation of ligands, and of the corresponding complexes, to obtain suitable compounds for therapeutic use, namely for the treatment of diabetes and as anti-tumour agents. The metal ions used have mainly been oxovanadium(IV and V), Cu(II) and Zn(II).

For the more promising compounds detailed speciation studies are made in aqueous solution. JCP is also involved in the study of the interaction of the compounds with plasma proteins (e.g. albumin and transferrin) and/or with DNA mainly using spectroscopic (EPR, CD, NMR, fluorescence) and electrophoretic techniques

Structural Characterization:

JCP has been involved in projects involving the use of spectroscopic techniques, namely circular dichroism, in the study of the stereochemistry of reactions of organic compounds and of metal complexes, and in the structural characterisation of peptides and proteins.

Analytical Chemistry

JCP has been involved in studies of speciation in solution using potentiometric and spectroscopic techniques, and the structural characterisation of the species formed.

JCP has also been involved in application of analytical techniques, namely for characterisation of ancient objects (e.g. tiles, paintings), analysis of marine sediments, and contaminants in environmental samples. In this context JCP has mainly dedicated to the development of chromatographic techniques.

Contact:

João da Costa Pessoa (Associate Professor)

Departamento de Engenharia Química e Biológica

Instituto Superior Técnico

Universidade Técnica de Lisboa

Av. Rovisco Pais

P - 1049-001 Lisboa

Portugal

telefone: (+351) 21 841 92 68

fax: (+351) 21 8464455

email: joao.pessoa@ist.utl.pt

Webpage: http://dequim.ist.utl.pt/docentes/1131/english

The Seventh International Symposium on the Chemistry and Biological Chemistry of Vanadium

The 7th International Symposium on the Chemistry and Biological Chemistry of Vanadium - V7 Symposium- which will be held in Toyama, Japan, from the 6th to the 9th of October, 2010.
This Conference focuses on all aspects of Vanadium Chemistry and Biochemistry.


Scientific Topics
1) Vanadium Inorganic Chemistry - Coordination, Speciation and Structure
2) Vanadium Bioinorganic and Biological Chemistry
3) Vanadium Transport, Toxicology and Enzymology
4) Therapeutic Applications of Vanadium Compounds
5) Vanadium-Induced or –Catalyzed Reactions
6) New Materials Containing Vanadium and their Processes


Venue
V7 Symposium will take place at Toyama Shimin Plaza, Otemachi 6,
Toyama 930-0084, Japan.

Web page
http://www.vanadiumseven.com/

Functional models of vanadium haloperoxidases

In the living system enzymes are found that work as catalyst. The catalytic ability of an enzyme is found in the so called active site, which is located in a cavity or cleft in the enzyme. This active site differs among enzymes, not only in size but also due to the presence of different catalytically active amino acids. Because of this, enzymes can stabilize different transition states and catalyse different reactions. Enzymes are highly chemoselective, regioselective and sterioselective. In spite of extensive research activity in this area the exact role of vanadium compounds in biological systems is far from being fully understood. Because of the complexity inherent to biochemical processes, chemists often concentrate their attention on model systems. Studies on the interaction of vanadates with biologically important ligands in order to find structural and/or functional models of haloperoxidases are numerous and have been the subject of several reviews. For better understanding of working mechanism and role of metal, numerous vanadium complexes have been studied [91]. cis-Dioxovanadium(V) (VO2+) in acidic aqueous solution is first reported functional mimic of VBrPO [92]. This has been shown to catalyse the bromination of 1,3,5-trimethoxybenzene (TMB) as well as the bromide mediated disproportionation of H2O2. In a first step, (Scheme 1.1) H2O2 is coordinated to vanadium giving red oxoperoxo [VO(O2)+] and yellow oxodiperoxo [VO(O2)2–] complexes [93]. The ratio between these two species depends on the H2O2 concentration and the pH. In a second step these complexes combine, yielding dioxotriperoxodivanadium(V) [(VO)2(O2)3], which is considered to be the actual oxidant. cis-Dioxovanadium(V) functions at acidic condition (~ pH 2 or less), because at lower acid concentration the amount of monoperoxovanadate is insufficient for dimerisation to [(VO)2(O2)3]. When suitable nucliophile is not available, second equivalent of hydrogen peroxide reduces the brominium ion to bromide ion and singlet oxygen [94]. The formation of Br+ is rate determining and results in singlet oxygen and brominated products.

Oxidative bromination of 1,3,5-trimethoxybenzene (TMB) catalysed by [VO(OMe)(MeOH)(sal-oap)] using H2O2 as oxidant has been reported by Butler et al. [95]. The brominated product 2-bromo-1,3,5-trimethoxybenzene was obtained in good yield. The bromination of 1,3,5-trimethoxybenzene to some extent has also been catalysed by [VO(hybeb)]2− and [VO(bhybeb)]– (H2hybeb = 1,2-bis(2-hydroxybenzylamido)benzene, ) [96]. Oxidative bromination of salicylaldehyde to 5-bromosalicylaldehyde and 3,5-dibromosalicylaldehyde catalysed by [VO2(sal-inh)]− (H2sal-inh = Schiff base derived from salicylaldehyde and isonicotinic acid hydrazide) encapsulated in the cavity of zeolite-Y has been reported by Maurya et al. [97]. The encapsulation of [VO(salen)] (H2salen = bis(salicylaldehyde) ethylenediimine) in zeolite Na-Y via the flexible ligand method is described. NaY-[VO(salen)] was found to be an effective catalyst for the room temperature epoxidation of cyclohexene using t-butylhydroperoxide (t-BuOOH) as the oxidant [98].

Other vanadium(V) complexes of multidentate ligands, e.g. salicylideneaminoacids, iminodiacetic acid, nitrilotriacetic acid, citric acid, tripodal ligands etc. are some common functional models for vanadate-bromo peroxidsase. Scheme 1.2 presents the widely accepted mechanism after carrying out many spectroscopic studies [99].

VANADIUM IN NATURALLY OCCURRING SYSTEM

Biological systems have developed haloperoxidases enzymes to catalyse the oxidation of chloride, bromide and iodide by hydrogen peroxide. On the basis of their cofactor requirement haloperoxidases are classified into the following three groups: heme-containing, vanadium-containing [56] and metal-free haloperoxidases [57]. Among them, vanadium haloperoxidase (VHPO) appears to be the most ubiquitous [58]. The bromoperoxidases involve in the polymerization of polyphenols holding the zygote to the membrane during the reproductive cycle of the cell [59]. The vanadium haloperoxidases represent a group of peroxidases that possess a single bound vanadate ion in a prosthetic group. These enzymes are able to oxidize a suitable electophilic halide species (X) to the corresponding hypohalous acid (HOX) in the presence of H2O2. The hypohalous acid species may further react to give a halogenated species. The presence of such enzyme in nature could do some way to explaining the formation of at least some of the wide diversity of halogenated compounds in environment [60].

The historical nomenclature convention of HPO is based on the most electronegative halide that the enzyme can oxidize (i.e., the chloroperoxidases (ClPO) can oxidize both Cl– and Br– and bromoperoxidases (BrPO) can oxidize Br– ). HPO does not have the driving force to oxidize the fluoride; however a fluorinating enzyme, fluorinase, has recently been isolated and is proposed to act by SN2 mechanism [61, 62]. In 1983, a naturally occurring vanadium-containing enzyme, vanadium bromoperoxidase (VBrPO), was discovered in the marine brown alga Ascophyllum nodosum [63]. It has trigonal bipyramidal coordination sphere including apical histdine and a meridionally bound oxo group; Figure 1.3 [64].
The oxidation state of the vanadium is +V and it does not change when hydrogen peroxide bind to give activated peroxointermidate species. Vanadium chloroperoxidases (VClPO), in the native and peroxo forms (Figure 1.4), have been isolated from the fungus Curvularia inaequalis [65, 66]. The enzyme contains α- helical with two four helix bundles as main structural motif, having 609 amino acids with molecular mass of 67488 Da. The active site is located at the top of the bundles [67]. A five-coordinated trigonal bipyrimidal V(V) moiety (Figure 1.4) is present in the native form which is coordinated by three nonprotein oxo groups in the equatorial plane and one His496 and a hydroxy group at the axial positions. The oxygens are hydrogen bonded to several amino acid residues of the protein chain. The nitrogen of His496 coordinates to vanadium and hence is the only direct bond from the protein to the metal center. The apical V-O bond length is 1.93 Å and the V-N bond is 1.96 Å, three equatorial V-O bonds are about 1.65 Å long.
In the peroxo form (Figure 1.5), the peroxide ligand is bound in a η2-manner in the equatorial plane. The apical oxygen ligand detaches and gives a distorted tetragonal pyramid coordination geometry around the vanadium centre with the two peroxo oxygens having V-O bond length ~ 1.87 Å and O-O is 1.47 Å. One oxygen (V-O bond length 1.93 Å) and the nitrogen (V-N bond length 2.19 Å) are in the basal plane while one oxygen (V-O bond length 1.60 Å) is in the apical position.
Carallina officinalis has been isolated from red algae and shows a high degree of amino acid homology in their active centre and has almost identical structural feature as have been reported for other enzymes [68].

In the last decade peroxidases, particularly chloroperoxidase have been shown to catalyse a variety of synthetically useful oxygen transfer reactions with H2O2, including enantioselective oxidation of sulfides [69, 70]. Vanadium haloperoxidases, such as vanadium chloroperoxidase from Curvularia inaequalis are much more stable. The vanadium-dependent bromoperoxidase from Corallina officinalis mediates the enantioselective oxidation of aromatic sulfides [71, 72]. The brown seaweed Ascophyllum nodosum mediate the formation of the (R)-enantiomer of the methyl phenyl sulfoxide with 91 % enantiomeric excess, whereas the red seaweed Corallina pilulifera mediates formation of the (S)-enantiomer (55 % enantiomeric excess) under optimal reaction conditions [73]. Recently Butler et al. have reported vanadium bromoperoxidase catalyzed biosynthesis of halogenated marine natural products [74].
In 1986, a vanadium nitrogenase enzyme was isolated from each of the two soil bacteria, Azotobacter chroococcum [75] and A. vinelandii [76, 77]. In vanadium-nitrogenases, vanadium is in a low to medium oxidation state as an integral part of an iron-sulphur cluster [78] which activates and reductively protonates various unsaturated substrates [79]. The coordination sphere around vanadium is probably octahedral (33 in Figure 1.6) and is similar to that of molybdenum in the structurally characterized molybdenum-nitrogenase [78, 80]. Thus, in vanadium-nitrogenase, vanadium is coordinated to histidine and the vicinal hydroxide and carboxylate groups of homocitrate in addition to three sulphide ions from iron-cluster.
The vanadium-iron protein of vanadium nitrogenases extracted from Azotobactor chroococcum contains an iron-vanadium cofactor. It is suggested that the nitrogen fixation requires specific interactions between Fe-V cofactor (Fe-Vaco) or Fe-Mo cofactor (Fe-Moco) and their respective polypeptides [81]. The vanadium nitrogenases [82] are multicomponent metalloenzyme complexes that are capable of reducing dinitrogen to ammonia, and hence to a form accessible by plants [83].
Many nitrogenases consist of a Fe-S cluster and a molybdenum-dependent component [84]. The first vanadium containing nitrogenase, i.e. a V-Fe-protein, was isolated and purified in 1986 from certain nitrogen-fixing bacteria [75].
Complexes have been designed that model parts of the structure of the V-Fe cofactor. The coordination atom is S in place of N and/or O coordination. Dixovanadium(V) complex (34 – 39 in Figure 1.7) having O,N, and S atoms have been prepared and structurally characterized in order to model in order to model nitrogenases [85 – 90].

Antiamoebic activity of Vanadium

Vanadium complexes have also shown encouraging results on the in vitro antiamoebic activity. Amoebiasis is the infection of the human gastrointestinal tract by Entamoeba histolytica, a protozoan parasite that is capable of invading the intestinal mucosa and can infect almost every organ of the body. The most frequent form of extra intestinal amoebiasis is the amoebic liver abscess. Being responsible for approximately 100,000 deaths annually, placing it a second only to malaria in mortality due to protozoan parasite [50, 51]. Metronidazole (MNZ, 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole) is the most effective antiamoebic medication [52]. This, however, induces certain tumors in rodents and is mutagenic towards bacteria [53].

The ideal treatment for amoebiasis does not yet exist, mainly due to the toxicity of current antiamoebic drugs [54]. In vitro tests of the antiamoebic activity of dioxovanadium(V) complexes [K(H2O)n[VO2(X-sal-sbdt)] ( n = 2 or 3, H2X-sal-sbdt = Schiff base derived from salicylaldehyde and S-benzyldithiocarbazate, X = H, 5-Cl, 5-Br) against Entamoeba histolytica, show comparable (when X = H and 5-Cl) or substantially better (when X = 5-Br) amoebocidal action than metronidazole [55].

Antitumor activity of Vanadium

Various vanadium complexes are effective for antitumor activity; bis(cyclopentadienyl)-cis-dichlorovanadium(IV) and peroxovanadated(V) are the most active [48, 49]. Dioxovanadium(V) complexes of the type [VO2(X-sal-tsc)] [where H2X-sal-tsc = Schiff base derived from salicylaldehyde, 5-bromosalicylaldehyde, 2-hydroxy-1-naphthaldehyde and semicarbazide, N4-n-butylsemicarbazide and N4-(2-naphthyl)semicarbazide] exhibit selective cytotoxicity on TK-10 human tumor cell lines. A significant effect on the antitumor activity of the vanadium complexes by structural modifications on the semicarbazone moiety has been indicated [50]. Peroxovanadates(V) with or without organic ligands also exhibit antitumor activity. The active roles of hetero ligands in modifying the antitumor and toxicity of peroxovanadium(V) have also been indicated. A the set of 14 oxoperovanadium(V) complexes of the types (NH4)4[O{VO(O2)2}2], M3[VO(O2)2(C2O4)] and M[VO(O2)L] (L = malate, citrate, iminodiacetate, nitrilotriacetate and ethylenedianinetetraacetate) has been tested for the toxicity and antitumor activity against L1210 murine leukemia to examine the biological properties. Study shows that these complexes increase the life span by about 25 % [51].

Insulin mimetic property of vanadium

Vanadium was widely used as a therapeutic agent in the late 18th century, treating a variety of disease including anemia, tuberculosis, rheumatism and diabetes [18]. Vanadium may play significant role for nutrition in human [6]. Several nutritional studies have revealed that the deficiency of vanadium may impediment the proper growth and development of chick and rat [19].
Diabetes mellitus is one of the most threatening and costly epidemics [20] and classified as Type I, insulin dependent or Type II, non insulin dependent (Type I: where there is no production of insulin in the pancreatic β–cells and thus patients must take exogenous insulin to supplement its deficiency and Type II: where there is insulin production in the body, but its secretion or cellular response is not satisfactory). People with Type II diabetes are not dependent on exogenous insulin as much as patients with Type I diabetes, but may need it to control their blood glucose levels [21]. Non- insulin dependent diabetes mellitus is most common form of diabetes in adult humans [22]. Insulin is a hormone which is essential both for metabolising of fat and carbohydrates [23]. The increased insulin promotes glucose uptake by the liver and gut, as well as by peripheral tissue (adipose and muscle), which results in the energy production and storage as needed by the organism [24]. Insulin is not orally active. As such oral ingestion of exogenous insulin does not work as biologically active hormone.
Obesity is an important risk factor for the development of insulin resistance in Type II diabetes [25]. The majority of patients with Type II diabetes are obese, and it has been demonstrated that weight gain correlates with deterioration of insulin resistance, whereas weight loss correlates with the improvement of insulin sensitivity.
A new turning point occurred in 1985, when Heyliger et al. demonstrated that oral administration of vanadate to streptozocin- treated diabetic rats (STZ rats), lowered the high level of glucose to normal, though they have a high toxicity. During the last decade, vanadium compounds have been found to act like insulin in all three main target tissues of the hormone, namely skeletal muscles, adipose and liver. Vanadium compounds are, therefore, of particular interest. By contrast vanadium compounds can be orally administrated, thereby potentially eliminating the need for daily insulin injection in diabetic individuals [26]. Since then research has been undertaken to find insulin-mimetic vanadium compounds to be used as oral substitute of insulin [27]. Vanadium ions show in vitro insulin-mimetic effect [28]. Low molecular weight metal complexes enhance the lipophilicity, membrane transport and bioavailability. The vanadyl V(IV) is less toxic to rats than the vanadate V(V) state [29] and hence vanadium(IV) state is proposed to be a possible active form of vanadium in mimicking or enhancing insulin action by interacting with the glucose transporter. The oral treatment with vanadate improves insulin sensitivity in skeletal muscle of Type II diabetic patients and results in reduced fasting plasma glucose concentration and suppression of hepatic glucose production [30].
Insulin activities of vanadium compounds are related to their potent inhibition of protein tyrosine phosphatases (PTPs). The organovanadium compounds have been shown to have superior insulin activities probably as a consequence of better bioavailability of these compounds or more potent activity at enzyme active site. Bis(maltolato)oxovanadium(IV) (BMOV), a potent insulin sensitiser, was shown to be a reversible, competitive phosphatase inhibitor that inhibited phosphatase activity in cultured cell and enhanced insulin receptor activation in vivo [31]. In fact, bis(maltolato)oxovanadium(IV) (BMOV) is the most widely tested complex among many proposed insulin mimetic vanadium complexes [27, 32 – 35]. The efficacy of the drug is possibly due to its interaction with human serum albumin (HSA) [36]. The generation of VO4 from BMOV in ‘physiologic’ solutions and the uncomplexed vanadium as an active component has been suggested by Peters et al. [31]. The closely related analogue bis(ethylmaltolato)oxovanadium(IV) (BEOV) has completed phase I clinical trials for the treatment of Type II diabetes mellitus and study suggests that there were no adverse health effects in any of the (nondiabetic) volunteers [37]. Oxidation state of metal ion, interaction of complexes with human serum albumin (HSA) [36, 38] and design of ligands have been indicated to play an important role in modifying the biological effects of metal based drugs [39].
Several types of neutral and low molecular weight vanadium(IV) complexes with organic ligands have been designed and investigated in animal model systems for the treatment of diabetes. Vanadium-dithiocarbamate complexes have been reported as potent orally active insulin-mimetic for the treatment of insulin-dependent diabetes mellitus in rats. Sakurai et al. [40], and Rehder et al. [41] have screened toxicity and insulin mimetic activity of a whole range of oxovanadium(IV), oxovanadium(V) and oxoperoxovanadium(V) complexes 1 – 17 presented in Figure 1.1; while details of other complexes (18 – 32 in Figure 1.2) screened for insulin-mimetic activity have been provided in review articles [23, 42]. Ammonium salt of dipicolinato oxovanadium(V) is a clinically useful oral hypoglycemic agent with no toxicity in cats with naturally occurring diabetes mellitus [42]. Simple peroxo compounds have also been screened for their insulin-mimetic action [43, 44].
It has been observed that the mixture of H2O2 and vanadate or vanadium(V) oxide were more potent in controlling the blood glucose level in rats than either vanadate or H2O2 alone [45, 46]. Literature also cites insulin-mimetic properties of peroxovanadium(V) compounds with nucleic bases such as uracil and cytocin [47].

TOXIC EFFECT OF VANADIUM

Vanadium is toxic both as a cation and as an anion [15]. The toxicity of vanadium has been found to be high when it is given intravenous, low when it is orally administered, and intermediate in the case of respiratory exposure. Toxicity as observed by weight lose, poor appetite, vomiting and diarrhea has been associated with ingestion of vanadium compounds therefore the therapeutic index of some vanadium complexes can be quit narrow [16]. Recent efforts focused on identifying vanadium compounds with increased therapeutic potency and decreased toxicity. The recent successes achieved on transition metal complexes having organic ligands suggest that modification of the metal ion on combining with organic ligands not only increases efficacy but also decreases toxicity [17]. V(III) is readily oxidized to V(IV) and V(V) at physiological pH and V(IV) is lees toxic than V(V).

VANADIUM IN BIOLOGY

Many essential/ trace elements play an important role in a number of biological processes by activating or inhibiting enzymatic reactions, by competing the permeability of cell membranes, maintaining genomic stability and/or by other mechanisms [5].
The role of vanadium in biochemistry has attracted attention for the last three decades. It could be used as inhibitor for nucleases and phosphatases [6]. Cantley and coworkers revealed a potent inhibitor of Na+/K+ – ATPase, widely used to study the mechanism of the sodium-potassium pump [7,8]. This pump is necessary for proper transport of materials across cell membranes to maintain ionic equilibrium.
Vanadium(V) (H2VO4−) enters into cells probably through the phosphate transport mechanism and reduced to vanadium(IV) through one-electron reduction in the gastrointestinal tract. VO2+ undergoes auto oxidation to vanadate in the presence of oxygen, whereas glutathione, ascorbate, cysteine and similar reducing agents can reduce vanadate. Thus, endogenous reducing agents and dissolved oxygen ensure that both vanadium(V) and vanadium(IV) species are present in serum. Vanadium has been found in its +IV oxidation state in mammalian lung and heart tissues [9] whereas +V oxidation state is common in kidney, liver and erythrocytes. It has also been suggested that extra cellular vanadium exists primarily as vanadium(V) and exclusively vanadium(IV) inside the cells [10]. The processes of interactions between vanadium species and serum albumin are still a challenge for scientists. However, the deposition of the vanadium in different tissue, obtained from in vitro experiments performed in different laboratories on several animals, follows the order: bone > kidney > liver > spleen > intestine  stomach, blood, muscle, testes, lungs and brain. The excretion of the small fraction of ingested and not retained vanadium occurs mainly through urine, as low molecular weight VO2+ complexes. Biliar excretion seems to be a secondary route [11–14].

INTRODUCTORY

Vanadium, named after the Nordic Goddess “Vanadis”, is a trace element that occurs in concentrations ranging from 0.1 – 3.0 nmol/g in most mammalian cells. Its concentration is about 136 ppm in the earth’s crust and is nineteenth element in the order of abundance. Anthropogenic sources include the combustion of fossil fuels, particularly residual fuel oils, which make up the single largest overall release of vanadium to the atmosphere. Vanadium has been reported to be an essential bio-element [1] for certain organisms, including tunicates, bacteria and some fungi. The physiological role of vanadium is not known but its importance has been indicated for the normal growth and development [2]. Crans and coworkers have outlined five specific ways by which vanadium interacts with proteins [3, 4]. Vanadium with atomic number 23 and electronic configuration [Ar]3d34s2, can exits in at least six oxidation states. Oxidation states +III, +IV and +V are most common but +III oxidation state is reducing in nature and difficult to exist in aqueous (pH~ 7.0) solution. Oxidation states +IV and +V are generally stabilized through V-O bond, and oxocations [VO]2+, [VO]3+ and [VO2]+ are most common for biological systems.
The presence of vanadium in vanadium based enzymes e.g. vanadate-dependent haloperoxidases and vanadium nitrogenase attracted attention of researchers to develop coordination chemistry of vanadium in search of good models for these enzymes. Studies on the metabolism and detoxification of vanadium compounds under physiological conditions, stability and speciation of vanadium complexes in biofluides, and potential therapeutic and catalytic applications have further influenced the coordination chemistry of vanadium.

Vanadium Chemistry References

1. Hopkins, L.L.Jr.; Cannon, H.L.; Miesch, A.T.; Welch, R.M.; Nielsen, F.H., “Trace elements related to health and disease: Vanadium”, Geochem. Environ., 1977, 2, 93 – 107.

2. Nielsen, F.H., “Evidence of the essentiality of arsenic, nickel, and vanadium and their possible nutritional significance”, Adv. Nutr. Res., 1980, 3, 157 – 172.

3. Crans, D.C.; Simone, C.M., “Nonreductive interaction of vanadate with an enzyme containing a thiol group in the active site: Glycerol-3-phosphate dehydrogenase”, Biochem., 1991, 30, 6734 – 6741.

4. Drueckhammer, D.G.; Durrwachter, J.R.; Pederson, R.L.; Crans, D.C.; Wong, C.H., “Reversible and in situ formation of organic arsenates and vanadates as organic phosphate mimics in enzymatic reactions: Mechanistic investigation of aldol reactions and synthetic applications”, J.Org. Chem., 1989, 54, 70 – 77.

5. Sky-Peck, H.H., “Trace metals and neoplasia”, Clin. Physiol. Biochem., 1986, 4, 99 – 111.

6. Chasteen, N.D., “The biochemistry of vanadium”, Struc. Bonding, 1983, 53, 105 – 138.

7. Cantley, L.C.; Josephson, L.; Warner, R.; Yanaisawa, M.; Lechene, C.; Guidotti, G., “Vanadate is a potent (Na, K)-ATPase inhibitor found in ATP derived from muscle”, J. Biol. Chem., 1977, 252, 7421 – 7423.

8. Josephson, L.; Cantley, L.C., “Isolation of a potent (Na -K) stimulated ATPase inhibitor from striated muscle”, Biochem., 1977, 16, 4572 – 4578.

9. Cantley, L.C.; Aisen, P., “The fate of cytoplasmic vanadium. Implications on (Na,K)-ATPase inhibition”, J. Biol. Chem., 1979, 254, 1781 – 1784.

10. Nechay, B.R.; Nanninga, L.B.; Nechay, P.S.E., “Vanadyl(IV) and vanadate(V) binding to selected endogenous phosphate, carboxyl, and amino ligands; calculations of cellular vanadium species distribution”, Arch. Biochem. Biophys., 1986, 251, 128 – 138.

11. Sharma, R.P.; Oberg, S.G; Parker, R.D, “Vanadium retention in rat tissues following acute exposures to different dose levels”, J. Toxicol. Environ. Health, 1980, 6, 45 – 54.
12. Sabbioni, E.; Marafante, E., “Metabolic patterns of vanadium in the rat”, Bioinorg. Chem., 1978, 9, 389 – 407.

13. Peckauskas, R.A.; Termine, J.D.; Pullman, I., “ESR investigation of the binding of acidic biopolymers to synthetic apatite”, Biopoly., 1976, 15, 569 – 581.

14. Peckauskas, R.A.; Pullman, I.; Termine, J.D., “ESR investigation of the binding of some neutral polyamino acids to synthetic apatite”, Biopoly., 1977, 16, 199 – 206.

15. Venugopal, B.; Luckey, T.D., “Metal toxicity in mammals. 2. Chemical toxicity of metals and metalloids”, New York, Plenum Press, 1978, pp. 220 – 226.

16. Sheehter, Y.; Shisheva, A., “Vanadium salts and the future treatment of diabetes”, Endeavour, 1993, 17, 27 – 31.

17. Thompson, K.H.; Yuen, V.G.; McNeill, J.H.; Orvig, C., “Chemical and pharmacological studies of a new class of antidiabetic vanadium complexes”, ACS. Symp. Ser., 1998, 711, 329 – 343.

18. Willsky, G.R., “Vanadium in biological systems physiology and biochemistry”, Chasteen, N.D., Ed.; Kluwer Academic Publishers: Dordrecht, Netherlands, 1990, 1 – 24.

19. Waters, M.D., “Toxicology of vanadium: Advances in modern toxicology. Vol. 2. Toxicology of trace elements”, Goyer, R.A.; Mehlman, M.A., Ed. New York, Wiley, 1977, pp. 147 – 189.

20. WHO, Diabetes Mellitus, Reports of a WHO Study Group, WHO Technical Report Series, 1985, pp. 727 – 876.

21. Zimmet, P.; Alberti, K.G.M.M.; Shaw, J., “Global and societal implications of the diabetes epidemic”, Nature, 2001, 414, 782 – 787.

22. Crans, D.C.; Yang, L.; Jakusch, T.; Kiss, T., “Aqueous chemistry of ammonium (dipicolinato)oxovanadate(V): The first organic vanadium(V) insulin-mimetic compound”, Inorg. Chem., 2000, 39, 4409 – 4416.

23. Thompson, K.H.; Mc Neill, J.H.; Orvig, C., “Vanadium compounds as insulin mimics”, Chem. Rev., 1999, 99, 2561 – 2571.

24. Czech, M.P., “Molecular basis of insulin action”, Annual. Rev. Biochem., 1977, 46, 359 – 384.
25. Reaven, G.M., “Role of insulin resistance in human disease”, Diabetes, 1988, 37, 1595 – 1607.

26. Heyliger, C.E.; Tahiliani, A. G.; Mc Neill, J. H., “Effect of vanadate on elevated blood glucose and depressed cardiac performance of diabetic rats”, Science, 1985, 227, 1474 – 1477.

27. Caravan, P.; Gelmini, L.; Glover, N.; Herring, F.G.; MeNeill, J.H., “Reaction chemistry of BMOV, bis(maltolato)oxovanadium(IV), a potent insulin mimetic agent”, J. Am. Chem. Soc., 1995, 117, 12759 – 12770.

28. Tolman, E.L.; Barris E.; Burns M.; Pansini A.; Partridge R., “Effects of vanadium on glucose metabolism”, Life Sci., 1979, 25, 1159 – 1164.

29. Hudson, F.T.G., “Toxicology and biological significance”, Elsevier, New York, 1964, p. 140.

30. Cusi, K.; Cukier. S.; DeFronzo, R.A.; Torres, M.; Puchulu, F.M.; Redondo, J.C., “Vanadyl sulfate improves hepatic and muscle insulin sensitivity in Type II diabetes”, J. Clin. Endo. Meta., 2001, 86, 1410 – 1417.

31. Peters, K.G.; Davis, M.G.; Howard, B.W.; Pokross, M.; Rastogi, V.; Diven, C.; Greis, K.D.; Eby-Wilkens, E.; Maier, M.; Evdokimov, A.; Soper, S.; Genbauffe, F., “Mechanism of insulin sensitization by BMOV (bis maltolato oxo vanadium); unliganded vanadium(VO4) as the active component”, J. Inorg. Biochem., 2003, 96, 321 – 330.

32. Yuen, V.G.; Orvig, C.; McNeill, J.H., “Glucose-lowering effects of a new organic vanadium complex, bis(maltolato)oxovanadium(IV)”, Can. J Physiol. Pharmacol, 1993, 71, 263 – 269.

33. McNeill, J.H.; Yuen, V.G.; Hoveyda, H.R.; Orvig, C., “Bis(maltolato) oxovanadium(IV) is a potent insulin mimic”, J. Med. Chem., 1992, 35, 1489 – 1491.

34. Sun, Y.; James, B.R.; Rettig, S.J.; Orvig, C., “Oxidation kinetics of the potent insulin mimetic agent bis(maltolato)oxovanadium(IV) (BMOV) in water and in methanol”, Inorg. Chem., 1996, 35, 1667 – 1673.

35. McNeill, J.H.; Yuen, V.G.; Dai, S.; Orvig, C. “Increased potency of vanadium using organic ligands”, Mol. Cell. Biochem, 1995, 153, 175 – 180.

36. Loboiron, B.D.; Thompson, K.H.; Hanson, G.R.; lam, E.; Aebischer, N.; Orvig, C., “New insights into the interactions of serum proteins with bis(maltolato)oxovanadium(IV): Transport and biotransformations of insulin-enhancing vanadium pharmaceuticals”, J. Am. Chem. Soc. 2005, 127, 5104 – 5115.

37. Thompson, K.H.; Loboiron, B.D.; Sun, Y.; Bellman, K.D.D.; Setyawati, I.A.; Patrick, B.O.; Karunaratne, V.; Rawji, G.; Wheelar, J.; Sutton, K.; Bhanot, S.; Cassidy, C.; McNeil, J.H.; Yuen, V.G.; Orvig, C., “Preparation and characterization of vanadyl complexes with bidentate maltol-type ligands; in vivo comparisons of anti-diabetic therapeutic potential”, J. Biol. Inorg. Chem., 2003, 8, 66 – 74.

38. Thompson, K.H.; Orvig, C., “Metal complexes in medicinal chemistry: New vistas and challenges in drug design”, Dalton Trans., 2006, 761 – 764.

39. Sakurai, H.; Kojima, Y.; Yoshikawa, Y.; Kawabe, K.; Yasui, H., “Antidiabetic vanadium(IV) and zinc(II) complexes”, Coord. Chem. Rev., 2002, 226, 187 – 198 and references cited there in.

40. Sakurai, H.; Watanabe, H.; Tamura, H.; Yasui, H.; Matsushita, R.; Takada, J., “Insulin-mimetic vanadyl-dithiocarbamate complexes”, Inorg. Cheim. Acta., 1998, 283, 175 – 183.

41. Rehder, D.; Pessoa, J.C.; Geraldes, C.F.G.C.; Castro, M.M.C.A.; Kabanos, T.; Kiss, T.; Meier, B.; Micera, G.; Pettersson, L.; Rangel, M.; Salifoglou, A.; Turel, I.; Wang, D., “In vitro study of the insulin-mimetic behaviour of vanadium(IV,V) coordination compounds”, J. Biol. Inorg. Chem., 2002, 7, 384 – 396.

42. Crans, D.C., “Chemistry and insulin-like properties of vanadium(IV) and vanadium(V) complexes”, J. Inorg. Biochem., 2000, 80,123 – 131.

43. Posner, B.I.; Faure, R.; Bergess, J.W.; Beven, A.P.; Lachance, D.; Jhang, S.G.; Fantus, I.G.; Nag, J.B.; Hall, D.A.; Lum, S.B.; Shaver, A.J., “Peroxo vanadium compounds: A new class of potent phosphotyrosinephosphatase inhibitors which are insulin mimetic”, J. Biol. Chem., 1994, 269, 4596 – 4604.

44. Shaver, A.J.; Hall, D.A.; Nag, J.B.; Lebius, A.M.; Hynes, R.C.; Posner, B.I., “Bisperoxovanadium compounds: Synthesis and reactivity of some insulin mimetic complexes”, Inorg. Chim. Acta., 1995, 229, 253 – 260.

45. Fantus, I.G.; Kadota, S.; Deragon, G.; Foster, B.; Posner, B.I., “Pervanadate (peroxide(s) of vanadate) mimics insulin action in rat adipocytes via activation of the insulin receptor tyrosine kinase”, Biochem., 1989, 28, 8864 – 8871.

46. Kadota, S.; Fantus, I.G.; Deragon, G.; Guyda, H.J.; Posner, B.I., “Stimulation of insulin like growth factor II receptor binding and insulin receptor kinase activity in rat adipocytes. Effect of vanadate and H2O2”, J. Biol. Chem., 1987, 262, 8252 – 8356.

47. Sarkar, A.R.; Mondal, S., “Insulin mimetic peroxo complexes of vanadium containing uracil or cytosine as ligands”, Metal Based Drugs, 2000, 7, 157 – 164.

48. Kopf-Maier, P.; Wagner, W.; Kopf, H.D., “Different inhibition pattern of the nucleic acid metabolism after in vitro treatment with titanocene and vanadocene dichlorides”, Naturwissenschaften, 1981, 68, 272 – 273.

49. Cruz, T.F; Morgan, A; Min, W., “In vitro and in vivo antineoplastic effects of orthovanadate”, Molecul. Cell. Biochem., 1995, 153, 161 – 166.

50. Nobĺia, P.; Vieites, M.; Parajón-Costa, B.S.; Baran, E.J.; Cerecetto, H.; Draper, P.; Gonz alez, M.; Piro, O.E.; Castellano, E.E.; Azqueta, A.; Lopez de Cerain, A.; Monge-Vega, A.; Gambino, D., “Vanadium(V) complexes with salicylaldehyde semicarbazone derivatives bearing in vitro antitumor activity towards kidney tumor cells (K-10): Crystal structure of [VO2(5-bromosalicylaldeyhyde semicarbazone)]”, J. Inorg. Biochem., 2005, 99, 443 – 451.

51. Djoedjevic, C.; Wampler, G.L., “Antitumor activity and toxicity of peroxo heteroligand vanadates(V) in relation to biochemistry of vanadium”, J. Inorg. Biochem., 1985, 25, 51 – 55.

52. Edwards, D.I., “Nitroimidazoles”, Antibiot. Chemother., 1997, 31, 404 – 415.

53. Caylor, K.B.; Cassimatis, M.K., “Metronidazole neurotoxicosis in two cats”, J. Am. Anim. Hosp. Assoc., 2001, 37, 258 – 262.

54. Wright, C.W.; Phillipson, J.D., “Natural products and the development of selective antiprotozoal drugs”, Phytother. Res., 1990, 4, 127 – 139.

55. Maurya, M.R.; Khurana, S.; Shailendra, Azam, A.; Zhang, W.; Rehder, D. “Synthesis, characterisation and antiamoebic studies of dioxovanadium(V) complexes containing ONS donor ligands derived from S-benzyldithiocarbazate” Eur. J. Inorg. Chem., 2003, 1966 – 1973.

56. Butler, A.; Walker, J.V., “Marine haloperoxidases”, Chem. Rev., 1993, 93, 1937 – 1944.

57. Kirk, O.; Conrad, L.S., “Metal-free haloperoxidases: Fact or artifact”, Ang. Chem., Inter. Ed., 1999, 38, 977 – 979.

58. Butler, A.; Carter-Franklin, J.N., “The role of vanadium bromoperoxidase in the biosynthesis of halogenated marine natural products”, Natural Product Reports, 2004, 21, 180 – 188.

59. Vreeland, V.; Waite, J.H.; Epstein, L., “Polyphenols and oxidases in substratum adhesion by marine algae and mussels”, J. Phycol., 1998, 34, 1 – 8.

60. Barnett, P.; Hermrika, W.; Dekker; H.L.; Muijsers, A.O.; Renirie, R.., “Isolation, characterization, and primary structure of the vanadium chloroperoxidase from the fungus Embellisia didymospora”, J. Biol. Chem., 1998, 273, 23381 – 23387.

61. Dong, C.; Huang, F.; Deng, H.; Schaffrath, C.; Spencer, J.B.; O'Hagan, D.; Naismith, H.J., “Crystal structure and mechanism of a bacterial fluorinating enzyme”, Nature, 2004, 427, 561 – 565.

62. O'Hagan, D.; Schaffrath, C.; Cobb, S.L.; Hamilton, J.T.G.; Murphy C.D., “Biochemistry: Biosynthesis of an organofluorine molecule”, Nature, 2002, 416, 279 – 280.

63. Vilter, H., “Peroxidases from phaeophyceae: A vanadium(V)-dependent peroxidase from Ascophyllum nodosum”, Phytochem., 1984, 23, 1387 – 1390.

64. Kusthardt U; Hedman B; Hodgson K.O; Hahn R; Vilter H., “High-resolution XANES studies on vanadium-containing haloperoxidase: pH-dependence and substrate binding”, Federation of Eur. Biochem. Soc., 1993, 329, 5 – 8.

65. Messerschmidt, A.; Wever, R., “X-ray structure of a vanadium-containing enzyme: Chloroperoxidase from the fungus Curvularia inaequalis”, Proc. Natl. Acad. Sci. U.S.A., 1996, 93, 392 – 396.

66. Messerschmidt, A.; Prade, L.; Wever, R., “Implications for the catalytic mechanism of the vanadium-containing enzyme chloroperoxidase from the fungus Curvularia inaequalis by X-ray structures of the native and peroxide form”, Biol. Chem., 1997, 378, 309 – 315.

67. Simons, B.H.; Barnett, P.; Vollenbroek, E.G.M.; Dekker, H.L.; Muijsers, A.O.; Messerschmidt, A., Wever, R., “ Primary structure and characterization of the vanadium chloroperoxidase from the fungus Curvularia inaequalis”, Eur. J. Biochem., 1995, 229, 566 – 574.

68. Isupov, M.I.; Dalby, A.R.; Brindley, A.; Izumi, Y.; Tanabe, T.; Murshudov, G.N.; Littlechild, J.A., “Crystal structure of vanadium dependent bromoperoxidase from Corallina officinalis”, J. Mol. Biol., 2000, 299, 1035 – 1049.

69. van Deurzen, M.P.J.; Remkes, I.J.; van Rantwijk, F.; Sheldon, R.A.., “Chloroperoxidase catalyzed oxidations in t-butyl alcohol/water mixtures”, J. Mol. Catal. A: Chem., 1997, 117, 329 – 337.

70. van Deurzen, M.P.J.; van Rantwijk, F.; Sheldon, R.A., “Selective oxidations catalyzed by peroxidases”, Tetrahedron, 1997, 53, 13183 – 13220.

71. Hemrika W; Renirie R; Dekker H L; Barnett P; Wever R, “From phosphatases to vanadium peroxidases: A similar architecture of the active site”, Proc. Natl. Acad. Sci. U.S.A., 1997, 94, 2145– 2149.

72. Neuwald, A.F., “An unexpected structural relationship between integral membrane phosphatases and soluble haloperoxidases”, Protein Sci., 1997, 6, 1764 – 1767.

73. ten Brink, H.B.; Schoemaker, H.E.; Wever, R., “Sulfoxidation mechanism of vanadium bromoperoxidase from Ascophyllum nodosum: Evidence for direct oxygen transfer catalysis”, Eur. J. Biochem., 2001, 268, 132 – 138.

74. Jayme N.; Carter-Franklin; Butler, A., “Vanadium bromoperoxidase-catalyzed biosynthesis of halogenated marine natural products”, J. Am. Chem. Soc., 2004, 126, 15060 – 15066.

75. Robson, R.L.; Eady, R.E.; Richardson, T.H.; Miller, R.W.; Hawkins, M.; Postgate, J.R., “The alternative nitrogenase of Azotobacter chroococcum is a vanadium enzyme”, Nature, 1986, 322, 388 – 390.

76. Hales, B.J.; Case, E.E.; Morningstar, J.E.; Dzeda, M.F.; Mauterer, L.A., “Isolation of a new vanadium-containing nitrogenase from Azotobacter vinelandii”, Biochem., 1986, 25, 7251 – 7255.

77. Hales, B.J.; Langosch, D.J.; Case, E.E., “Isolation and characterization of a second nitrogenase Fe-protein from Azotobacter vinelandii”, J. Biol. Chem., 1986, 261, 15301 – 15306.

78. Chen, J.; Christiansen, J.; Tittsworth, R.C.; Hales, B.J.; George, S.J.; Coucouvanis, D.; Cramer, S.P., “Iron EXAFS of Azotobacter vinelandii nitrogenase molybdenum-iron and vanadium-iron proteins”, J. Am Chem. Soc., 1993, 115, 5509 – 5515.

79. Pau, R.N., “Biology and Biochemistry of Nitrogen Fixation”, Dilworth, M.J.; Glenn, A.R. (Eds.), Elsevier, Amsterdam, 1991, Ch. 3.
80. Chan, H.K.; Kim, J.; Res, D.C., “The nitrogenase Fe Mo-cofactor and P-cluster pair: 2.2 Å resolution structures”, Science, 1993, 260, 792 – 794.

81. Smith, B.E.; Eady, R.R.; Lowe, D.J.; Gormal, C., “The vanadium-iron protein of vanadium nitrogenase from Azotobactor Chroococcum contains an iron-vanadium cofactor”, Biochem., 1988, 250, 299 – 302.

82. Wever, R.; Hemrika, W., “Vanadium in the Environment, Part One: Chemistry and Biochemisty”, Nriagu, J.O., Ed.; John Wiley & Sons, New York, 1998, Chapter 12.

83. Holm, R.H.; Kennepohl, P.; Solomon, E.I., “Structural and functional aspects of metal sites in biology”, Chem. Rev., 1996, 96, 2239 – 2314.

84. Butler, A.; Carrano, C.J., “Coordination chemistry of vanadium in biological systems”, Coord. Chem. Rev., 1991, 109, 61 – 105.

85. Tsagkalidis, W.; Rodewald, D.; Rehder, D., “Coordination and oxidation of vanadium(II) by 1,2-bis(2-sulfidophenylsulfanyl)ethane(2-) (S4): The structures of [V(S4)tmeda], the first example of vanadium(II)-sulfide coordination, and of [V3(-O)2(S2)4(tmeda)2] [S2 = 1,2-benzenedithiolate(2-)]”, J. Chem. Soc., Chem. Commun., 1995, 165 – 166.

86. Tasiopoulos, A.J.; Vlahos, A.T.; Keramidas, A.D.; Kabanos, T.A.; Deligiannakis, Y.G.; Raptopoulou, C.P.; Terzis, A., “Models of oxovanadium(IV) protein interactions: The first oxovanadium(IV) complexes with dipeptides”, Angew. Chem. Intl. Ed. Engl., 1996, 35, 2531 – 2533.

87. Farahbakhsh, M.; Nekola, H.; Scmidt, H.; Rehder, D., “Thio-ligation to vanadium: The NSSN and SNO donar sets (N equals pyridine, N equals enamine; S equals thioether, S equals thiolate)”, Chem. Ber. Recueil, 1997, 130, 1129 – 1133.

88. Cornman, C.R.; Stauffer, T.C.; Boyle, P.D., “Oxidation of a vanadium(V)-dithiolate complex to a vanadium(V)-(2), (2)-disulfenate complex”, J. Am. Chem. Soc., 1997, 119, 5986 – 5987.

89. Tsagkalidis, W.; Rehder, D., “Characterization of bio-related vanadium and zinc complexes containing tetradentate dithiolate -disulphide, -diamine and -amine-amide ligands”, J. Biol. Inorg. Chem., 1996, 1, 507 – 514.

90. Milanesio, M., Viterbo, D., Hernandez, R. P., Rodriguez, J. D., Ramirez-Ortiz, J.; Valdes-Martinez, J., “Synthesis, characterization and novel crystal structure of (salicylal-4-phenylthiosemicarbazidato) ammonium dioxovanadate(V) with a V–S bond”, Inorg. Chim. Acta., 2000, 306, 125 – 129.

91. Schwendt, P.; Svancarek, P.; Smatanova, I.; Marek, J., “Stereospecific formation of α-hydroxycarboxylato oxo peroxo complexes of vanadium(V). Crystal structure of (NBu4)2[V2O2(O2)2( -lact)2]•2H2O and (NBu4)2 [V2O2(O2)2( -lact)( -lact)]•2H2O”, J. Inorg. Biochem., 2000, 80, 59 – 64.

92. De la Rosa, R.; Clague, M.J.; Butler, A., “A functional mimic of vanadium bromoperoxidase”, J. Am. Chem. Soc., 1992, 114, 760 – 761.

93. Campbell, N.J.; Dengel, A.C.; Griffith, W.P., “Studies on transition metal peroxo complexes. The nature of peroxovanadates in aqueous solution”, Polyhedron, 1989, 8, 1379 – 1386.

94. Everett, R.R.; Kanofsky, J.R.; Butler, A., “Mechanistic investigations of the novel non-heme vanadium bromoperoxidases. Evidence for singlet oxygen production”, J. Biol. Chem. 1990, 265, 4908 – 4914.

95. Butler, A.; in Reedijk, J.; Bouwman, E., (Eds.), Bioinorganic Catalysis, 2nd ed. (Chapter 5), Marcel Dekker, New York 1999.

96. Slebodnick, C.; Hamstra, B.J.; Pecoraro, V.L., “Modeling the biological chemistry of vanadium: Structural and reactivity studies elucidating biological functions”, Struct. Bonding, 1997, 89, 51 – 107.

97. Maurya, M.R.; Saklani, H.; Agarwal, S., “Oxidative bromination of salicylaldehyde by potassium bromide / H2O2 catalysed by dioxovanadium(V) complexes encapsulated in zeolite-Y: A functional model of haloperoxidases”, Catal. Commun., 2004, 5, 563 – 568.

98. Balkus Jr. K.J.; Khanrnamedova, A.K.; Dixon, K. M.; Bedioui, F., “Oxidations catalyzed by zeolite ship-in-a-bottle complexes”, Appl. Catal. A: Gen., 1996, 143,159 – 173.

99. Ligtenbarg, A.G.J.; Hage, R.; Feringa, B.L., “Catalytic oxidations by vanadium complexes”, Coord. Chem. Rev., 2003, 237, 89 – 101.

100. Conte, V.; Di Furia, F.; Licini, G., “Liquid phase oxidation reactions by peroxides in the presence of vanadium complexes”, Appl. Catal. A: Gen., 1997, 157, 335 – 361.

101. Thompson, K.H.; Yuen, V.G.; McNeill, J.H.; Orvig, C., “Vanadium compounds: Chemistry, biochemistry, and therapeutic applications”, Tracey, A.S.; Crans, D.C., Eds; Oxford University Press, New York, NY, 1998, pp. 329 – 343.

102. Butler, A.; Clague, M.J.; Meister, G.E., “Vanadium peroxide complexes”, Chem. Rev. 1994, 94, 625 – 638.

103. Mimoun, H.; Mignard, M.; Brechot, P.; Saussine, L., “Selective epoxidation of olefins by oxo[N-(2-oxidophenyl)salicylidenaminato]vanadium(V) alkylperoxides. On the mechanism of the Halcon epoxidation process”, J. Am. Chem. Soc., 1986, 108, 3711 – 3718.

104. Shul'pin, G.B.; Ishii, Y.; Sakaguchi, S.; Iwahama, T., “Oxidation with the O2-H2O2-vanadium complex-pyrazine-2-carboxylic acid, reagent 11. Oxidation of styrene, phenylacetylene, and their derivatives with the formation of benzaldehyde and benzoic acid”, Russian Chem. Bull., 1999, 48, 887 – 890.

105. Rehder, D.; Santoni, G.; Licini, G. M.; Schulzke, C.; Meier, B., “The medicinal and catalytic potential of model complexes of vanadate-dependent haloperoxidases”, Coord. Chem. Rev., 2003, 237, 53 – 63.

106. Sun, J.; Zhu, C.; Dai, Z.; Yang, M.; Pan, Y.; Hu, H., “Efficient asymmetric oxidation of sulfides and kinetic resolution of sulfoxides catalyzed by a vanadium-salan system”, J. Org. Chem. 2004, 69, 8500 – 8503.

107. Bolm, C., “Vanadium-catalyzed asymmetric oxidations”, Coord. Chem. Rev. 2003, 237, 245 – 256.

108. ten Brink, H.B.; Tuynman, A.; Dekker, H.L.; Hemrika, W.; Izumi, Y.; Oshiro, T.; Schoemaker, H.E.; Wever, R., “Enantioselective sulfoxidation catalyzed by vanadium haloperoxidases”, Inorg. Chem. 1998, 37, 6780 – 6784.

109. Ando, R.; Yagyu, T.; Maeda, M., “Characterization of oxovanadium(IV) Schiff-base complexes and those bound on resin, and their use in sulfide oxidation”, Inorg. Chim. Acta, 2004, 357, 2237 – 2244.

110. Ando, R.; Inden, H.; Sugino, M.; Ono, H.; Sakaeda, D.; Yagyu, T.; Maeda, M., “Spectroscopic characterization of amino acid and amino acid ester Schiff-base complexes of oxovanadium and their catalysis in sulfide oxidation”, Inorg. Chim. Acta, 2004, 357, 1337 – 1344.

111. Ando, R.; Ono, H.; Yagyu, T.; Maeda, M., “Spectroscopic characterization of mononuclear, binuclear, and insoluble polynuclear oxovanadium(IV) Schiff base complexes and their oxidation catalysis”, Inorg. Chim. Acta, 2004, 357, 817 – 823.

112. Ando, R.; Mori, S.; Hayashi, M.; Yagyu; T.; Maeda, M., “Structural characterization of pentadentate salen-type Schiff-base complexes of oxovanadium(IV) and their use in sulfide oxidation”, Inorg. Chim. Acta, 2004, 357, 1177 – 1184.

113. Maurya, M.R.; Sikarwar, S.; Joseph, T.; Manikandan, P.; Halligudi, S.B., “Synthesis, characterisation and catalytic potentials of polymer anchored copper(II), oxovanadium(IV) and dioxomolybdenum(VI) complexes of 2(-hydroxymethyl) benzimidazole”, React. Funct. Polymer, 2005, 63, 71 – 83.

114. Maurya, M.R.; Saklani, H.; Kumar, A.; Chand, S., “Dioxovanadium(V) complexes of dibasic tridentate ligands encapsulated in zeolite-Y for the liquid phase catalytic hydroxylation of phenol using H2O2 as oxidant”, Catal. Lett., 2004, 93, 121 – 127.

115. Maurya, M.R.; Kumar, M.; Titinchi, S.J.J; Chand. S., “Oxovanadium(IV) Schiff base complexes encapsulated in Zeolite-Y as catalysts for the liquid-phase hydroxylation of phenol”, Catal Lett., 2003, 86, 97 – 105.

116. Radosevich, A.T.; Musich, C.; Toste, F.D., “Vanadium-catalyzed asymmetric oxidation of α-hydroxy esters using molecular oxygen as stoichiometric oxidant”, J. Am. Chem. Soc., 2005, 127, 1090 – 1091.

117. Rowe, R.A.; Jones, M.M., “Vanadium(IV) oxy(acetylacetonate)”, Inorg. Synth., 1957, 5, 113 – 116.

118. Bhattacharya, M., “An efficient and direct synthesis of bis(acetylacetonato)oxovanadium(IV)”, J. Chem. Res.( S), 1992, 415.

119. Calviou, L.J.; Collison, D.; Garner, C.D.; Mabbs, F.E.; Passand, M.A.; Peanson, M., “Imidazole and related heterocyclic ligand complexes of oxovanadium(IV)-potential models for the reduced vanadium site of the seaweed bromoperoxidases”, Polyhedron, 1989, 8, 1835 – 1837.

120. Carrano, C.J.; Nunn, C.M.; Quan, R.; Bonadies, J.A.; Pecoraro, V.L., “Monomeric and dimeric vanadium(IV) and -(V) complexes of N-(hydroxyalkyl)salicylideneamines: Structures, magnetochemistry and reactivity”, Inorg. Chem., 1990, 29, 944 – 951.

121. Maurya, M.R.; Khurana, S., “Potassium bis(2-[-hydroxyalkyl/ aryl]benzimidazolato) dioxovanadates(V) through base assisted aerial oxidation of the corresponding oxovanadium(IV) complexes”, J. Chem. Res. (S), 2002, 260 – 261.

122. Maurya, M.R., “Development of the coordination chemistry of vanadium through bis(acetylacetonato)oxovanadium(IV): Synthesis, reactivity and structural aspects”, Coord. Chem. Rev., 2003, 237, 163 – 181.

123. Schmidt, H.; Bashirpoor, M.; Rehder, D., “Structural characterization of possible intermediates in vanadium-catalysed sulfide oxidation” J. Chem. Soc., Dalton Trans., 1996, 3865 – 3870.

124. Asgedom, G.; Sreedhara, A.; Kivikoski, J.; Valkonen, J.; Rao, C.P., “Mononuclear cis-dioxovanadium(V) anionic complexes [VO2L]– {H2L =[1 + 1] Schiff base derived from salicylaldehyde (or substituted derivatives) and 2-amino-2-methylpropan-l-ol}: Synthesis, structure, spectroscopy, electrochemistry and reactivity studies”, J. Chem. Soc., Dalton Trans., 1995, 2459 – 2466 .

125. Chakravarty, J.; Dutta, S.; Chandra, S.; Basu, P.; Chakaravorty, A., “Chemistry of variable-valence VO2+ (z = 2, 3) complexes; synthesis, structure and metal redox of new (VVO(ONO)(ON)] and VIVO(ONO)(NN) families”, Inorg. Chem., 1993, 32, 4249 – 4255.

126. Samanta, S.; Mukhopadhyay, S.; Mandal, D.; Butcher, R.J.; Chaudhury, M., “Adduct formation between alkali metal ions and anionic LVVO2– (L2– = tridentate ONS ligands) species: Syntheses, structural investigation, and photochemical studies”, Inorg. Chem., 2003, 42, 6284 – 6293.

127. Baruah, B.; Das, S.; Chakravorty, A., “Vanadate chelate of esters of monoionised diols and carbohydrates”, Coord. Chem. Rev., 2003, 237, 135 – 146.

128. Colpas, G.J.; Hamstra, B.J.; Kampf, J.W.; Pecoraro, V.L., “The preparation of VO3+ and VO2+ complexes using hydrolytically stable, asymmetric ligands derived from Schiff base precursors”, Inorg. Chem., 1994, 33, 4669 – 4675.

129. Maurya, M.R.; Khurana, S.; Zhang, W.; Rehder, D., “Biomimetic oxo-, dioxo- and oxo-peroxo-hydrazonato vanadium(IV/V) complexes”, J. Chem. Soc., Dalton Trans., 2002, 3015 – 3023.

130. Dutta, S.K.; Kumar, S.B.; Bhattacharyya, S.; Tiekink, E.R.T.; Chaudhury, M., “Intermolecular electron transfer in (BzimH)[(LOV)2O] (H2L = S-methyl 3-((2-hydroxyphenyl)methyl)dithiocarbazate): A novel µ-Oxo dinuclear oxovanadium(IV/V) compound with a trapped- valence (V2O3)3+ core”, Inorg. Chem., 1997, 36, 4954 – 4960.

131. Samanta, S.; Ghosh, D.; Mukhopadhyay, S.; Endo, A.; Weakley, T.J.R.; Chaudhury, M., “Oxovanadium(IV) and -(V) complexes of dithiocarbazate-based tridentate Schiff base ligands: Syntheses, structure, and photochemical reactivity of compounds involving imidazole derivatives as coligands”, Inorg. Chem., 2003, 42, 1508 – 1517.

132. Dutta, S.K.; Samanta, S.; Kumar, S.B.; Han, O.H.; Burckel, P.; Pinkerton, A. A.; Chaudhury, M., “Mixed-oxidation divanadium(IV,V) compound with ligand asymmetry: Electronic and molecular structure in solution and in the solid state”, Inorg. Chem., 1999, 38, 1982 – 1988.

133. Stankiewicz, P.J.; Tracey, A.S.; Crans, D.C., “Metal ions in biological systems,” Sigel, H.; Sigel, A., Eds.; Marcel Dekker: New York, 1995, pp 287 – 324.

134. Crans, D.C., “Aqueous chemistry of labile oxovanadates: Relevance to biological studies”, Comments Inorg. Chem., 1994, 16, 1 – 31.

135. Crans, D.C., “Enzyme interactions with labile oxovanadates and other polyoxometalates”, Comments Inorg. Chem., 1994, 16, 35 – 76.

136. Mahroof-Tahir, M.; Keramidas, A.D.; Goldfrab, R.B.; Anderson, O.P.; Miller, M.M.; Crans, D.C., “Solution and solid state properties of [N-(2-hydroxyethyl)iminodiacetato]vanadium(IV), -(V), and -(IV/V) complexes”, Inorg. Chem., 1997, 36, 1657 – 1668.

137. Mondal, A.; Sarkar; S.; Chopra, D.; Row, T.N.G.; Pramanik, K.; Rajak, K.K., “Family of mixed-valence oxovanadium(IV/V) dinuclear entities incorporating N4O3-coordinating heptadentate ligands: Synthesis, structure, and EPR spectra”, Inorg. Chem., 2005, 44, 703 – 708.

138. Hills, A.; Hughes, D.L.; Leigh, G.J.; Sanders, J.R., “A linear tetranuclear vanadium-oxygen assembly” J. Chem. Soc., Chem. Commun., 1991, 827 – 829.

139. Hughes, D.L.; Kloinkos, U.; Leigh, G.J.; Malwald, M.; Sanders, R.; Sudbrake, C., “New polymeric compounds containing vanadium-oxygen chains”, J. Chem. Soc. Dalton Trans., 1994, 2457 – 2466.

140. Kabanos, T.A.; Keramidas, A.D.; Mentzafos, D.; Terzis, A., “Vanadyl(IV)-amide binding. The preparation and X-ray crystal structure of [VO(pycac)] {H2pycac = N-[2-(4-oxopentane-2-ylideneamino)phenyl]pyridine-2-carboxamide}”, J. Chem.Soc., Chem. Commun., 1990, 1664 – 1665.

141. Kabanos, T.A.; Keramidas, A.D.; Papaioannou, A.B.; Terzis, A., “Synthesis and characterization of vanadium(III) and oxovandium(IV/V) species with deprotonated amide ligands”, J. Chem. Soc., Chem. Commun., 1993, 643 – 645.

142. Keramidas, A.D.; Papaioannou, A.B.; Vlahos, A.; Kabanos, T.A.; Bonas, G.; Makriyannis, A.; Rapropoulou, C.P.; Terzis, A., “Model investigations of protein vanadium interactions. Synthetic, structural and physical studies of vanadium(III) and oxovanadium(IV/V) complexes with amidate ligands”, Inorg. Chem., 1996, 35, 357 – 367.

143. Hanson, G.R.; Kabanos, T.A.; Keramidas, A.D.; Mentzafos, D.; Terzis, A., “Oxovanadium(IV)-amide bonding. Synthesis, structure and physical studies of {N-[2-(4-oxopent-2-en-2-ylamino)phenyl]pyridine-2carboxamido} oxovanadium(IV) ”, Inorg. Chem., 1992, 31, 2587 – 2594.

144. Borovic, A.S.; Dewey, T.M.; Reymond, K.N., “Amidate ligands for the oxovandium(IV) cation: Design, synthesis, structure and spectroscopic and electrochemical properties”, Inorg. Chem., 1993, 32, 413 – 421.

145. Cornman, C.R.; Geiser-Bush, K.M.; Singh, P., “Structural and spectroscopic characterization of a novel vanadium(V)-amide complex”, Inorg. Chem., 1994, 33, 4621 – 4622.

146. Klich, P.R.; Daniher, A.T.; Challen, P.R.; MeConville, D.B.; Youngs, W.J. “Vanadium(IV) complexes with mixed O, S donor ligands; synthesis, structures and properties of the anions. Tris(2-mercapto-4-methyl phenolato)vanadium(IV) and bis(2-mercaptophenolato)oxovanadate(IV)”, Inorg. Chem., 1996, 35, 347 – 356.

147. Kojima, K.; Taguchi, H.; Tsuchimoto, M.; Nakajima, K., “Tetra dentate Schiff base oxovanadium(IV) complexes: Structures and reactivities in the solid state”, Coord. Chem. Rev., 2003, 237, 183 – 196.

148. Li, X.; Lah, M.S.; Pecoraro, V.L., “Vanadium complexes of the tridentate Schiff base ligand N-salicylidene-N’-(2-hydroxyethyl)ethylenediamine: Acid-base and redox conversion between vanadium(IV) and vanadium(V) imino phenolates”, Inorg. Chem., 1988, 27, 4657 – 4664.

149. Hamstra, B.J; Houseman, A.L.P.; Colpas, G.J.; Kampf, J.W.; LoBrutto, R.; Frasch, W.D.; Pecoraro, V.L., “Structural and solution characterization of mononuclear vanadium(IV) complexes that help to elucidate the active site structure of the reduced vanadium haloperoxidases”, Inorg. Chem., 1997, 36, 4866 – 4874.

150. Asgedom, G.; Sreedhara, A.; Kivikoski, J.; Kolehmainen, E.; Rao, C.P., “Structure, characterization and photoreactivity of monomeric dioxovanadium(V) Schiff base complexes of trigonal-bipyramidal geometry”, J. Chem. Soc., Dalton Trans., 1996, 93 – 97.

151. Clauge, M.J.; Keder, N.L.; Butler, A., “Biomimics of vanadium bromoperoxidase: Vanadium(V) Schiff base catalyzed oxidation of bromide by hydrogen peroxide”, Inorg. Chem., 1993, 32, 4754 – 4761.

152. Nanda, K.K.; Sinn, E.; Addison, A.W., “The first oxovanadium(V)-thiolate complex, [VO(SCH2CH2)3N]”, Inorg. Chem., 1996, 35, 1 – 2.

153. Root, C.A.; Hoeschele, J.D.; Cornaman, C.R.; Kampf, J.W.; Pecoraro, V.L., “Structural and spectroscopic characterization of dioxovanadium(V) complexes with asymmetric Sciff base ligands”, Inorg. Chem., 1993, 32, 3855 – 3861.

154. Schmidt, Y.H.; Rehder, D., “The preparation and synthetic potential of chlorovanadium(V and IV) complexes supported by enamines and bis(enamines)”, Inorg. Chim. Acta, 1998, 267, 229 – 238.

155. Butler, A., “Mechanistic considerations of the vanadium haloperoxidases”, Coord. Chem. Rev., 1999, 187, 17 – 35.

156. Rehder, D., “The coordination chemistry of vanadium as related to its biological functions”, Coord. Chem. Rev., 1999, 182, 297 – 322.

157. Rehder, D., “Transition metals in biology and their coordination chemistry”, Trautwein, A.X., Ed.; Wiley-VCH, Weinheim, 1997, pp. 491 – 504.

158. Crans, D.C.; Smee, J.J.; Gaidamauskas, E.; Yang, L., “The chemistry and biochemistry of vanadium and the biological activities exerted by vanadium compounds”, Chem. Rev., 2004, 104, 849 – 902.

159. Weyand. M.; Hecht, H.J.; Kiesz, M.; Liaud, M. F.; Vilter, H.; Schomburg, D., “X-ray structure determination of a vanadium-dependent haloperoxidase from Ascophyllum nodosum at 2.0 Å Resolution”, J. Mol. Biol., 1999, 293, 595 – 611.

160. Balcells, D.; Maseras, F.; Ujaque, G., “Computational rationalization of the dependence of the enantioselectivity on the nature of the catalyst in the vanadium-catalyzed oxidation of sulfides by hydrogen peroxide”, J. Am. Chem. Soc., 2005, 127, 3624 – 3634.

161. Andersson, M.; Willetts, A.; Allenmark, S., “Asymmetric sulfoxidation catalyzed by a vanadium-containing bromoperoxidase”, J. Org. Chem., 1997, 62, 8455 – 8458.

162. Dembitsky, V.M., “Oxidation, epoxidation and sulfoxidation reactions catalysed by haloperoxidases”, Tetrahedron, 2003, 59, 4701 – 4720.

163. Li, X.; Zhou, K., “Crystal structure of tetramethylammonium (L)-histidinatobis(thiocyanato)vanadyl(IV) monohydrate”, J. Crystallogr. Spectrosc. Res., 1986, 16, 681 – 685.

164. Cornman, C.R.; Kampf, J.; Lah, M.S.; Pecoraro, V.L., “Modeling vanadium bromoperoxidase: Synthesis, structure, and spectral properties of vanadium(IV) complexes with coordinated imidazole”, Inorg. Chem., 1992, 31, 2035 – 2043.

165. Cornman C.R.; Colpas, G.J.; Hoeschele, J.D.; Kampf, J.; Pecoraro, V.L., “Implications for the spectroscopic assignment of vanadium biomolecules: structural and spectroscopic characterization of monooxovanadium(V) complexes containing catecholate and hydroximate based noninnocent ligands”, J. Am. Chem. Soc., 1992, 114, 9925 – 9933.

166. Cornman, C.R.; Kampf, J.; Pecoraro, V.L., “Structural and spectroscopic characterization of vanadium(V)-oxoimidazole complexes”, Inorg. Chem., 1992, 31, 1981 – 1983.

167. Smith II, T.S.; Root, C.A.; Kampf, J.W.; Rasmussen, P.G.; Pecoraro, V.L., “Reevaluation of the additivity relationship for vanadyl-imidazole complexes: correlation of the EPR hyperfine constant with ring orientation”, J. Am. Chem. Soc., 2000, 122, 767 – 775.

168. Fukui, K.; Ohya-Nishiguchi, H.; Kamada, H., “Electron spin-echo envelope modulation study of imidazole-coordinated oxovanadium(IV) complexes relevant to the active site structure of reduced vanadium haloperoxidases”, Inorg. Chem., 1998, 37, 2326 – 2327.

169. Vergopoulos, V.; Priebsch, W; Fritzsche, M.; Rehder, D., “Binding of L-histidine to vanadium. Structure of exo-[VO2{N-(2-oxidonaphthal)-His}]”, Inorg. Chem., 1993, 32, 1844 – 1849.

170. Crans, D.C.; Keramidas, A.D.; Amin, S.S.; Anderson, O.P.; Miller, S.M., “Six-coordinated vanadium(IV) and -(V) complexes of benzimidazole and pyridyl containing ligands”, J. Chem. Soc., Dalton Tans., 1997, 2799 – 2812.

171. Calviou, L.J.; Arber, J.M.; Collison, D.; Garner, C.D.; Clegg, W., “A structural model for vanadyl-histidine interactions: Structure determination of [VO(1-vinylimidazole)4Cl]Cl by a combination of X-ray crystallography and X-ray absorption spectroscopy”, J. Chem. Soc., Chem. Commun., 1992, 654 – 656.

172. Keramidas, A.D.; Miller, S.M.; Anderson, O.P.; Crans, D.C., “Vanadium(V) hydroxylamido complexes: Solid state and solution properties”, J. Am. Chem. Soc., 1997, 119, 8901 – 8915.

173. Crans, D.C.; Keramidas, A.D.; Hoover-Litty, H.; Anderson, O.P.; Miller, M. M.; Lemoine, L.M.; Pleasic-Williams, S.; Vandenberg, M.; Rossomando, A.J.; Sweet, L.J., “Synthesis, structure, and biological activity of a new insulinomimetic peroxovanadium compound: Bisperoxovanadium imidazole monoanion”, J. Am. Chem. Soc., 1997, 119, 5447 – 5448.

174. Crans, D.C.; Schelble, S.M.; Theisen, L.A., “Substituent effects in organic vanadate esters in imidazole-buffered aqueous solutions”, J. Org. Chem., 1991, 56, 1266 – 1274.

175. Dutta, S.K., Samanta, S.; Mukhopadhyay, S.; Burckel, P.; Pinkerton, A.A.; Chaudhury, M., “Spontaneous assembly of a polymeric helicate of sodium with LVO2 units forming the strand: Photoinduced transformation into a mixed-valence product”, Inorg. Chem., 2002, 41, 2946 – 2952.

176. Ceson, L.A.; Day, A.R., “Preparation of some benzimidazolylamino acids. Reactions of amino acids with o-phenylenediamines,” J. Org. Chem., 1962, 27, 581 – 586.

177. Dutta, R.L.; Syamal, “A. elements of magnetochemistry”, Affiliated East-West Press, New Delhi, 2nd ed., 1993, p.8.

178. Santoni, G; Rehder, D., “Structural models for the reduced form of vanadate-dependent peroxidases: Vanadyl complexes with bidentate chiral Schiff base ligands”, J. Inorg. Biochem., 2004, 98, 758 – 764.

179. Cornman, C.R.; Geiser-Bush, K.M.; Rowley, S.P.; Boyle, P.D., “Structural and electron paramagnetic resonance studies of the square pyramidal to trigonal bipyramidal distortion of vanadyl complexes containing sterically crowded Schiff base ligands”, Inorg. Chem., 1997, 36, 6401 – 6408.

180. Wang, X.; Zhang, X.M.; Liu, H. X., “ Synthesis, properties and structure of vanadium(IV) Schiff base complex (VO)[salphen]CH3CN”, Polyhedron, 1995, 13, 293 – 296.

181. Plass, W., “Magneto-structural correlations in dinuclear d1-d1 complexes: Structure and magnetochemistry of two ferromagnetically coupled vanadium(IV) dimmers”, Angew. Chem. Int. Ed., 1996, 33, 627 – 631.

182. Gao, S.; Weng, Z.Q.; Liu, S.X., “Syntheses and characterization of four novel monooxovanadium(V) hydrazone complexes with hydroxamate or alkoxide ligand”, Polyhedron, 1998, 17, 3595 – 3606.

183. Westland, A.D.; Haque, F.; Bouchard, J.M., “Peroxo complexes of molybdenum and tungsten stabilized by oxides of amines, phosphines, and arsines. Stability studies”, Inorg. Chem., 1980, 19, 2255 – 2259.

184. Nakamoto, K., “Infrared and raman spectra of inorganic and coordination compounds”, 3rd Ed.; John Wiley & Sons, New York, 1978, p. 241.

185. Smith II, T.S.; LoBrutto, R.; Pecoraro, V.L., “Paramagnetic spectroscopy of vanadyl complexes and its applications to biological systems”, Coord. Chem. Rev., 2002, 228, 1 – 18.

186. Garribba, E.; Lodyga-Chruscinska, E.; Micera, G.; Panzanelli, A.; Sanna, D., “Binding of oxovanadium(IV) to dipeptides containing histidine and cysteine residues”, Eur. J. Inorg. Chem., 2005, 1369 – 1382.

187. Tasiopoulos, A.J.; Troganis, A.N.; Evangelou, A; Raptopoulou, C.P.; Terzis, A.; Deligiannakis, Y.; Kabanos, T.A., “Synthetic analogs for oxovanadium(IV) - glutathione interaction: An EPR, synthetic and structural study of oxovanadium(IV) compounds with sulfhydryl-containing pseudopeptides and dipeptides”, Chem. Eur. J., 1999, 5, 910 – 921.

188. Saladino, A.C.; Larsen, S.C., “Computational study of the effect of the imidazole ring orientation on the EPR parameters for vanadyl-imidazole complexes”, J. Phys. Chem. A, 2002, 106, 10444 – 10451.

189. Rehder, D.; Weidemann, C.; Duch, A.; Priebsch, W., “Vanadium-51 shielding in vanadium(V) complexes: A reference scale for vanadium binding sites in biomolecules”, Inorg. Chem., 1988, 27, 584 – 587.

190. Rehder, D., “Transition metal nuclear magnetic resonance”, Pregosin, P.S., Ed.; Elsevier, New York, 1991, pp 1 – 58.

191. Macedo-Ribeiro, S.; Hemrika, W.; Renirie, R.; Wever, R.; Messerschmidt, A., “X-ray crystal structures of active site mutants of the vanadium-containing chloroperoxidase from the fungus Curvularia inaequalis”, J. Biol. Inorg. Chem., 1999, 4, 209 – 219.

192. Maurya, M.R.; Agarwal, S.; Bader, C.; Rehder, D., “Dioxovanadium(V) complexes of ONO donor ligands derived from pyridoxal and hydrazides: Models of vanadate-dependent haloperoxidases”, Eur. J. Inorg. Chem., 2005, 1, 147 – 157.

193. Giacomelli, A.; Floriani, C.; De Souza Duarte, A.O.; Chiesi-Villa, A.; Guastino, C., “Chemistry and structure of an inorganic analog of a carboxylic acid: Hydroxobis(8-quinolinato)oxovanadium(V)“, Inorg. Chem., 1982, 21, 3310 – 3316.

194. Kosugi, M.; Hikichi, S.; Akita, V.; Moro-oka, Y., “Inter and intramolecular hydrogen-bonding interaction of hydroxo groups and steric effect of alkyl substituents on pyrazolyl rings in TpR ligands: Synthesis and structural characterization of chloro-, acetylacetonato-, and hydroxo complexes of VO2+ with TpPri2 and TpMe2 ligands”, Inorg. Chem., 1999, 38, 2567 – 2578.

195. Zampella, G.; Fantucci, P.; Pecorao, V.L.; De Gioia, L., “Reactivity of peroxo forms of the vanadium haloperoxidases cofactor. A DFT investigation”, J. Am. Chem. Soc., 2005, 127, 953 – 960.

196. Smith II, T.S; Pecoraro, V.L., “Oxidation of organic sulfides by vanadium haloperoxidase model complexes”, Inorg. Chem., 2002, 41, 6754 – 6760.

197. Bryliakov, K.P.; Talsi, E.P.; Kuhn, T.; Bolm, C., “Multinuclear NMR study of the reactive intermediates in enantioselective epoxidations of allylic alcohols catalyzed by a vanadium complex derived from a planar-chiral hydroxamic acid”, New. J. Chem., 2003, 27, 609 – 614.

198. Hulea, V.; Dumitriu, E., “Styrene oxidation with H2O2 over Ti-containing molecular sieves with MFI, BEA and MCM-41 topologies”, Appl. Catal. A: Gen., 2004, 277, 99 – 106.

199. Andersson, M.A.; Allenmark, S.G., “Asymmetric sulfoxidation catalyzed by a vanadium bromoperoxidase: substrate requirements of the catalyst”, Tetrahedron, 1998, 54, 15293 – 15304.

200. ten Brink, H.B.; Holland, H.L.; Schoemaker, H.E.; van Lingen, H.; Wever, R., “Probing the scope of the sulfoxidation activity of vanadium bromoperoxidase from Ascophyllum nodosum”, Tetrahedron: Asymmetry, 1999, 10, 4563 – 4572.

201. Arber, J.M.; deBoer, E.; Garner, C.D.; Hasnain, S.S.; Wever, R., “Vanadium K-edge X-ray absorption spectroscopy of bromoperoxidase from Ascophyllum nodosum”, Biochem., 1989, 28, 7968 – 7973.


202. deBoer, E.; Boon, K.; Wever, R., “Electron paramagnetic resonance studies on conformational states and metal ion exchange properties of vanadium bromoperoxidase”, Biochem., 1988, 27, 1629 – 1635.

203. Schuster, H.; Chiodini, P.L., “Parasitic infections of the intestine”, Curr. Opin. Infect. Dis., 2001, 14, 587 – 591.

204. Nigro, M.M.L.; Gadano, A.B.; Carballo, M.A., “Evaluation of genetic damage induced by a nitroimidazole derivative in human lymphocytes: Tinidazole (TNZ)”, Toxicol., 2001, 15, 209 – 213.

205. Moreno, S.N.; Docampo, R., “Mechanism of toxicity of nitro compounds used in the chemotherapy of trichomoniasis”, Environ. Health Perspect., 1985, 64, 199 – 208.

206. Akgun, Y.; Tacyldz, I.; Celik, Y., “Amebic liver abscess: changing trends over 20 years”, World J. Surg., 1999, 23, 102 – 106.

207. Conoor, T.H.; Stoeckel, M.; Evrard, J.; Legator, M.S., “The contribution of metronidazole and two metabolites to the mutagenic activity detected in urine of treated humans and mice”, Cancer Res., 1977, 37, 629 – 633.

208. Kapoor, K.; Chandra, M.; Nag, D.; Paliwal, J.K.; Gupta, R.C.; Saxena, R.C., “Evaluation of metronidazole toxicity: A prospective study”, Int. J. Clin. Pharmacol. Res., 1999, 19, 83 – 88.

209. Rosenkranz, H.S.; Speck, W.T., “Mutagenicity of metronidazole: Activation by mammalian liver microsomes”, Biochem. Biophys. Res. Commun., 1975, 66, 520 – 525.

210. Rowley, A.; Knight, C.; Skolimowski, M.; Edwards, D.I., “The relationship between misonidazole cytotoxicity and base composition of DNA”, Biochem. Pharmacol., 1980, 29, 2095 – 2098.

211. IARC Monographs on the evaluation of the carcinogenic risk of chemicals to humans, Suppl. 7, International Agency for Research on Cancer, Lyon. 1987 pp. 250 – 251.

212. Vanadium and its role in life [Metal ions in biological systems] Vol. 31; Sigel, H.; Sigel, A., Eds.; Marcel Dekker: New York, 1995.

213. Martinez, J.S.; Carrol, G.L.; Tschirret-Guth, R.A.; Altenhoff, G.; Little, R.D.; Butler, A., “On the regiospecificity of vanadium bromoperoxidase”, J. Am. Chem. Soc., 2001, 123, 3289 – 3294.

214. Rehder, D., “Vanadium nitrogenase”, J. Inorg. Biochem., 2000, 80, 133 – 136.

215. See chapter 2. for details.

216. Baran, E.J., “Oxovanadium(IV) and oxovanadium(V) complexes relevant to biological systems”, J. Inorg. Biochem., 2000, 80, 1 – 10.

217. Kiss, T.; Jakusch, T.; Pessoa, J.C.; Tomaz, I., “Interactions of VO(IV) with oligopeptides”, Coord. Chem. Rev., 2003, 237, 123 – 133.

218. Kiss, T.; Jakusch, T.; Kilyen, M.; Kiss, E.; Lakatos, A., “Solution speciation of bioactive Al(III) and VO(IV) complexes”, Polyhedron, 2000, 19, 2389 – 2401.

219. Dutta, S.K.; Tiekink, E.R.T.; Chaudhury, M., “Mono- and dinuclear oxovanadium(IV) compounds containing VO(ONS) basic core: Synthesis, structure and spectroscopic properties”, Polyhedron, 1997, 16, 1863 – 1871.

220. Maurya, M.R.; Khurana, S.; Zhang, W.; Rehder, D., “Vanadium(IV/V) complexes containing [VO]2+, [VO]3+, [VO2]+ and [VO(O2)]+ cores with ligands derived from 2-acetylpyridine and S-benzyl- or S-methyldithiocarbazate”, Eur. J. Inorg. Chem., 2002, 1749 – 1760.

221. Wang, V.; Ebel, M.; Schulzke, C.; Grüning, C.; Hazari, S.K.S.; Rehder, D., “Vanadium(IV and V) complexes containing SNO (dithiocarbonylhydrazone; thiosemicarbazone) donor sets”, Eur. J. Inorg. Chem., 2001, 935 – 942.

222. Dutta, S.K.; Samanta, S.; Ghosh, D.; Butcher, R.J.; Chaudhury, M., “Oxovanadium(V) and cobalt(III) complexes of dithiocarbazate-based Schiff base ligands: Formation of a thiadiazole ring by vanadium-induced cyclization of the coordinated ligand”, Inorg. Chem., 2002, 41, 5555 – 5560.

223. Bhattacharyya, S.; Mukhopadhyay, S.; Samanta, S.; Weakley, T.J.R.; Chaudhury, M., “Synthesis, characterization, and reactivity of mononuclear O,N-chelated vanadium(IV) and -(III) complexes of methyl 2-aminocyclopent-1-ene-1-dithiocarboxylate based ligand: Reporting an example of conformational isomerism in the solid state”, Inorg. Chem., 2002, 41, 2433 – 2440.

224. Tarafder, M.T.H.; Ali, M.A.; Saravanan, N.; Weng W.Y.; Kumar, S.; Umar-Tsafe, N.; Crouse, K.A.; Serdang, M., “Coordination chemistry and biological activity of two tridentate ONS and NNS Schiff bases derived from S-benzyldithiocarbazate”, Trans. Met. Chem., 2000, 25, 295 – 298.

225. Monga, V.; Thompson, K.H.; Yuen, V.G.; Sharma, V.; Patrick, B.O.; McNeill, J.H.; Orvig, C., “Vanadium complexes with mixed O,S anionic ligands derived from maltol: Synthesis, characterization, and biological studies”, Inorg. Chem., 2005, 44, 2678 – 2688.

226. Sakurai, H.; Sano, H.; Takiro, T.; Yasui, H., “An orally active antidiabetic vanadyl complex, bis(1-oxy-2-pyridinethiolato)oxovanadium(IV), with VO(S2O2) coordination mode; in vitro and in vivo evaluations in rats”, J. Inorg. Biochem., 2000, 80, 99 – 105.

227. Mishra, V.; Pandeya, S.N.; Pannecouque, C.; Witvrouw, M.; De Clercq, E., “Anti-HIV activity of thiosemicarbazone and semicarbazone derivatives of ()-3-menthone”, Arch. Pharm., 2002, 335, 183 – 186.

228. Condit, R.C.; Easterly, R.; Pacha, R.F.; Fathi, Z.; Meis, R.J., “A vaccinia virus isatin-beta-thiosemicarbazone resistance mutation maps in the viral gene encoding the 132-kDa subunit of RNA polymerase”, Virology, 1991, 185, 857 – 861.

229. Finch, R.A.; Liu, M.C.; Cory, A.H.; Cory, J.G.; Sartorelli, A.C., “Triapine (3-aminopyridine-2-carboxaldehyde thiosemicarbazone; 3-AP). An inhibitor of ribonucleotide reductase with antineoplastic activity”, Adv. Enzyme Regul., 1999, 39, 3 – 12.

230. Klayman, D.L.; Bartosevich, J.F.; Griffin, T.S.; Mason, C.J.; Scovill, J.P., “2-Acetylpyridine thiosemicarbazones. 1. A new class of potential antimalarial agents”, J. Med. Chem., 1979, 22, 855 – 862.

231. Wilson, H.R.; Revankar, G.R.; Tolman, R.L., “In vitro and in vivo activity of certain thiosemicarbazones against Trypanosoma cruzi”, J. Med. Chem., 1974, 17, 760 – 761.

232. Du, X.; Guo, C.; Hansell, E.; Doyle, P.S.; Caffrey, C.R.; Holler, T.P.; McKerrow, J.H.; Cohen, F.E., “Synthesis and structure-activity relationship study of potent trypanocidal thio semicarbazone inhibitors of the trypanosomal cysteine protease cruzain”, J. Med. Chem., 2002, 45, 2695 – 2707.

233. Feun, L.; Modiano, M.; Lee, K.; Mao, J.; Marini, A.; Savaraj, N.; Plezia, P.; Almassian, B.; Colacino, E.; Fisher, J.; MacDonald, S., “Phase I and pharmacokinetic study of 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP) using a single intravenous dose schedule”, Cancer Chemother. Pharmacol., 2002, 50, 223 – 229.

234. Diamond, L.S.; Harlow, D.R.; Cunnick, C.C., “A new medium for the axenic cultivation of Entamoeba histolytica and other Entamoeba”, Trans. R. Soc. Trop. Hyg., 1978, 72, 431 – 432.

235. O’Sullivan, D.G.; Sadler, P.W.; Webley, C., “Chemotherapeutic activity of isatin -4',4'-dialkylthiosemi-carbazones against infectious ectromelia”, Chemotherapia, 1963, 7, 17 – 26.

236. Ali, M.A.; Tarafder, M.T.H., “Metal complexes of sulfur and nitrogen-containing ligands: complexes of S-benzyldithiocarbazate and a Schiff base formed by its condensation with pyridine-2-carboxaldehyde”, J. Inorg. Nucl. Chem., 1977, 39, 1785 – 1791.

237. Das, M.; Livingstone, S.E., “Metal chelates of dithiocarbazic acid and its derivatives. IX. Metal chelates of ten new Schiff bases derived from S-methyldithiocarbazate”, Inorg. Chim. Acta, 1976, 19, 5 – 10.

238. Dutta, S.; Basu, P.; Chakravorty, A., “Chemistry of mononuclear and binuclear oxidic vanadium(V), VVVV, and VVVIV azophenolates”, Inorg. Chem., 1993, 32, 5343 – 5348.

239. Sangeetha, N.R.; Pal, S., “A family of dinuclear vanadium(V) complexes containing the {OV(-O)VO}4+ core: Syntheses, structures, and properties”, Bull. Chem. Soc. Jpn., 2000, 73, 357 – 363.

240. Pessoa, J.C.; Silva, J.A.L.; Vieira, A.L.; Vilas-Boas, L.; O’Brien, P.; Thornton, V., “Salicylideneserinato complexes of vanadium. Crystal structure of the sodium salt of a complex of vanadium(IV) and -(V)”, J. Chem. Soc., Dalton Trans., 1992, 1745 – 1749.

241. Gruning, C.; Schmidt, H.; Rehder, D., “A water-soluble, neutral {aqua-VV}2 complex with a biomimetic ONO ligand set”, Inorg. Chem. Commun., 1999, 2, 57 – 59.

242. Mondal, S.; Ghosh, P.; Chakravorty, A., “A family of  -amino acid salicylaldiminates incorporating the binuclear V2O33+ Core: Electrosynthesis, structure, and metal valence”, Inorg. Chem., 1997, 36, 59 – 63.

243. Cavaco, I.; Pessoa, J.C.; Costa, D.; Duarte, M.T.; Gillard, R.D.; Matias, P., “N-Salicylideneamino acidate complexes of oxovanadium(IV). Part 1. Crystal and molecular structures and spectroscopic properties”, J. Chem. Soc., Dalton Trans., 1994, 149 – 157.

244. Maurya, M.R.; Khurana, S.; Schulzke, C.; Rehder, D., “Dioxo- and oxovanadium(V) complexes of biomimetic hydrazone ONO donor ligands: Synthesis, characterisation, and reactivity”, Eur. J. Inorg. Chem., 2001, 779 – 788.

245. Wright, C.W.; O’Neill, M.J.; Phillipson, J.D.; Warhurst, D.C., “Use of microdilution to assess in vitro antiamoebic activities of Brucea javanica fruits, Simarouba amara stem, and a number of quassinoids”, Antimicrob. Agents Chemother., 1988, 32, 1725 – 1729.

246. Plass, W.; Pohlmann, A.; Yozgatli, H.K., “N-salicylidenehydrazides as versatile tridentate ligands for dioxovanadium(V) complexes”, J. Inorg. Biochem., 2000, 80, 181 – 183.

247. Colpas, G.J.; Hamstra, B.J.; Kampf, J.W.; Pecoraro, V.L., “Functional models for vanadium haloperoxidase: Reactivity and mechanism of halide oxidation”, J. Am. Chem. Soc., 1996, 118, 3469 – 3478.

248. Hamstra, B.J.; Colpas, G.J.; Pecoraro, V.L., “Reactivity of dioxovanadium(V) complexes with hydrogen peroxide: Implications for vanadium haloperoxidase”, Inorg. Chem., 1998, 37, 949 – 955.

249. Maurya, M.R.; Agarwal, S.; Bader C.; Ebel M.; Rehder, D., “Synthesis, characterisation and catalytic potential of hydrazonato-vanadium(V) model complexes with [VO]3+ and [VO2]+ cores”, Dalton transactions, 2005, 3, 537 – 544.

250. Bryliakov, K.P.; Karpyshev, N.N.; Fominsky, S.A.; Tolstikov, A.G.; Talsi, E. P., “51V and 13C NMR spectroscopic study of the peroxovanadium intermediates in vanadium catalyzed enantioselective oxidation of sulfides”, J. Mole. Catal. A: Chem., 2001, 171, 73 – 80.

251. Bolm, C.; Bienewald, F., “Asymmetric sulfide oxidation with vanadium catalysts and H2O2”, Angew. Chem. Int. Ed., 1996, 34, 2640 – 2642.

252. Hirao, T., “Vanadium in modern organic synthesis”, Chem. Rev. 1997, 97, 2707 – 2724.

253. Canali, L.; Sherrington, D.C., “Utilization of homogeneous and supported chiral metal(salen) complexes in asymmetric catalysis”, Chem. Soc. Rev. 1999, 28, 85 – 93.

254. Sherrington, D.C., “Polymer-supported metal complex alkene epoxidation catalysts”, Catal. Today, 2000, 57, 87 – 104.

255. Ogunwumi, S.B.; Bein, T., “Intrazeolite assembly of a chiral manganese salen epoxidation catalyst”, Chem. Commun., 1997, 9, 901 – 902.

256. Knops-Gerrits, P.P.; De Vos, D.; Thibault-Starzyk, F.; Jacobs, P.A., “Zeolite-encapsulated Mn(II) complexes as catalysts for selective alkene oxidation”, Nature., 1994, 369, 543 – 546.

257. Joseph, T.; Srinivas, D.; Gopinath, C.S.; Halligudi, S.B., “Spectroscopic and catalytic activity studies of VO(saloph) complexes encapsulated in Zeolite-Y and Al-MCM-41 molecular sieves”, Catal. Lett., 2002, 83, 209 – 214.

258. Awasarkar, P.A.; Gopinathan, S.; Gopinathan, C., “Organooxytitanium and organotin derivatives of dibasic tetradentate chelating disulfides”, Synth. React. Inorg. Met.Org. Chem., 1985, 15, 133 – 147.

259. Siddiqi, K.S.; Khan, N.H.; Kureshy, R.I.; Tabassum, S.; Zaidi, S.A.A., “Complexes of group(IV) metals with 5,5'-methylenebis(salicylaldehyde) and its Schiff base with hydrazine”, Indian J. Chem., 1987, 26, 492 – 494.

260. Groeneman, R.H.; MacGillivray, L.R.; Atwood, J.L., “One-dimensional coordination polymers based upon bridging terephthalate ions”, Inorg. Chem., 1999, 38, 208 – 209.

261. Maurya, M.R.; Jain, I.; Titinchi, S.J.J., “Coordination polymers based on bridging methylene group as catalysts for the liquid phase hydroxylation of phenol”, Appl. Catal. A: Gen., 2003, 249, 139 – 149.

262. Marvel, C.S.; Tarkoy, N., “Heat-stability studies on chelates from Schiff bases of salicylaldehyde derivatives”, J. Am. Chem. Soc., 1957, 79, 6000 – 6003.

263. Krishnamurthy, S.S.; Soundarajan, S., “Dimethylformamide complexes of rare earth nitrates”, J. Inorg. Nucl. Chem., 1966, 28, 1689 – 1692.

264. Dutton, J.C.; Fallon, G.D.; Murray, K.S., “Synthesis, structure, ESR spectra, and redox properties of (N,N'-ethylenebis(thiosalicylideneaminato)) oxovanadium(IV) and of related {S,N} chelates of vanadium(IV)”, Inorg. Chem., 1988, 27, 34 – 38.

265. Bonadies, J.A.; Butler, W.M.; Pecoraro, V. L.; Carrano, C.J., “Novel reactivity patterns of (N,N'-ethylenebis(salicylideneaminato))oxovanadium(IV) in strongly acidic media”, Inorg. Chem., 1987, 26, 1218 – 1222.

266. Srinivasan, K.; Michaud, P.; Kochi, J.K., “Epoxidation of olefins with cationic (salen)manganese(III) complexes. The modulation of catalytic activity by substituents”, J. Am. Chem. Soc., 1986, 108, 2309 – 2320.

267. Irie, R.; Ito, Y.; Katsuki, T., “Donor ligand effect in asymmetric epoxidation of unfunctionalized olefins with chiral salen complexes”, Syn. Lett., 1991, 265 – 266.

268. Kumar, S.B.; Mirajkar, S.P.; Pais, G.C.G.; Kumar, P.; Kumar, R., “Epoxidation of styrene over a titanium silicate molecular sieve TS-1 using dilute H2O2 as oxidizing agent”, J. Catal., 1995, 156, 163 – 166.

269. Reddy, E.J.S.; Khire, U.R.; Ratnasamy, P.; Mitra, R.B., “Cleavage of the carbon-carbon double bond over zeolites using hydrogen peroxide”, J. Chem. Soc., Chem. Commun., 1992,1234 – 1235.

270. Hulea, V.; Dumitriu, E., “Styrene oxidation with H2O2 over Ti-containing molecular sieves with MFI, BEA and MCM-41 topologies”, Appl. Catal. A: Gen., 2004, 277, 99 – 106.

271. Yin, D.; Qin, L.; Liu, J.; Li, C.; Jin, Y., “Gold nanoparticles deposited on mesoporous alumina for epoxidation of styrene: effects of the surface basicity of the supports”, J. Mol. Catal. A: Chem., 2005, 240, 40 – 48.

272. Butler, A., “Mechanistic considerations of the vanadium haloperoxidases”, Coord. Chem. Rev., 1999, 187, 17 – 35.

273. Casny, M.; Rehder, D., “Molecular and supramolecular features of oxo-peroxovanadium complexes containing O3N, O2N2 and ON3 donor sets”, Dalton Trans., 2004, 839 – 846.