N2O2-complexes of oxovanadium(IV) with 2,2′-dihydroxybenzophenone thiosemicarbazones: Synthesis, EPR and electrochemical studies

Kurt, Yasemin; İlhan-Ceylan, Berat; Açıkgöz, Muhammed; Tüzün, Elif; Atun, Gülten; Ülküseven, Bahrı

doi:10.1016/j.poly.2013.08.010

Cited by 14 publications

(3 citation statements)

References 39 publications

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“…The quasi-reversible redox couples at medium potentials (50-350 mV) were attributed to reduction of double bond in the -N 4 =CH-group of the thiosemicarbazones. [45] …”

Section: Electrochemical Studymentioning

confidence: 99%

Oxovanadium(IV) complexes based onS-alkyl-thiosemicarbazidato ligands. Synthesis, characterization, electrochemical, and antioxidant studies

İlhan-Ceylan

Tüzün

Kurt

et al. 2015

Journal of Sulfur Chemistry

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Reaction of VOSO 4 with 2-hydroxy-napthaldeyde-S-R-thiosemicarbazones (R: methyl, ethyl, propyl or allyl) and salicyl aldehyde yielded five-coordinate oxovanadium(IV) complexes having a N 1 ,N 4 -diarylidene-S-R-thiosemicarbazidato structures. The compounds were characterized by elemental analysis, magnetic measurements, electronic, infrared, 1 H-NMR, and electron paramagnetic resonance (EPR) spectra. The X-band EPR signals were recorded from powder forms and also in solution. All the complexes have a single asymmetric line shape and theoretical fit studies prove the presence of axial symmetry around the paramagnetic vanadium ions. A computer simulation of the EPR spectrum of each complex was carried out to derive the related EPR parameters. Cyclic voltammograms of the complexes exhibited two metal-based reversible redox peaks around 500 and − 800 mV corresponding to one electron oxidation/reduction of V IV O/V V O and V IV O/V III O, respectively. The reductive response in the 50-350 mV region was assigned to ligand reduction. Antioxidant activities of the compounds were determined with CUPric Reducing Antioxidant Capacity, 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid, and 1,1-diphenyl-2-picrylhydrazyl assays. The test results indicated that the antioxidant capacity of the compounds increases with the carbon number of saturated hydrocarbon chain on sulfur atom.

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“…The quasi-reversible redox couples at medium potentials (50-350 mV) were attributed to reduction of double bond in the -N 4 =CH-group of the thiosemicarbazones. [45] …”

Section: Electrochemical Studymentioning

confidence: 99%

Oxovanadium(IV) complexes based onS-alkyl-thiosemicarbazidato ligands. Synthesis, characterization, electrochemical, and antioxidant studies

İlhan-Ceylan

Tüzün

Kurt

et al. 2015

Journal of Sulfur Chemistry

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“…+1.0 V due to ligand oxidation (hydrazine‐based oxidation) . It also exhibits a reduction peak at –0.483 to –0.528 V, equivalent to two electrons, which is coupled with two closely associated peaks at –0.404 to –0.436 V and –0.889 to –0.972 V, attributed to the reduction of –N=CH– linkage of the ligand . The peak potentials are shifted (ca.…”

Section: Resultsmentioning

confidence: 99%

Vanadium Complexes Derived from Acetyl Pyrazolone and Hydrazides: Structure, Reactivity, Peroxidase Mimicry and Efficient Catalytic Activity for the Oxidation of 1‐Phenylethanol

et al. 2016

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Schiff bases obtained from the condensation of acetylpyrazolone (H2ap) with benzoyl hydrazide (bhz), furoyl hydrazide (fah), nicotinoyl hydrazide (nah) and isonicotinoyl hydrazide (inh) [H2ap‐bhz (I), H2ap‐fah (II) H2ap‐nah, (III) and H2ap‐inh (IV)], sharing a ONO donor set, upon reaction with [VIVO(acac)2] lead to the formation of [VIVO(ap‐bhz)(H2O)] (1), [VIVO(ap‐fah)(H2O)] (2), [VIVO(ap‐nah)(H2O)] (3) and [VIVO(ap‐inh)(H2O)] (4), respectively. These complexes slowly convert to monooxidovanadium(V) complexes [VVO(ap‐bhz)(OMe)(MeOH)] (11), [VVO(ap‐fah)(OMe)(MeOH)] (12), [VVO(ap‐nah)(OMe)(MeOH)] (13) and [VVO(ap‐inh)(OMe)(MeOH)] (14) in methanol. The reaction of aqueous K[H2VVO4] with the corresponding potassium salt of the ligands at neutral pH gives dioxidovanadium(V) complexes, K(H2O)[VVO2(ap‐bhz)] (5), K(H2O)0.5[VVO2(ap‐fah)] (6), [VVO2(Hap‐nah)] (9) and [VVO2(Hap‐nah)] (10). Acidification of solutions of 5 and 6 affords the neutral complexes [VVO2(Hap‐bhz)] (7) and [VVO2(Hap‐fah)] (8), respectively. All complexes were characterized by various spectroscopic techniques: FT‐IR, UV/Visible, EPR, NMR (1H, 13C and 51V); elemental analysis, thermal studies, cyclic voltammetry (CV) and single‐crystal X‐ray analysis. X‐ray diffraction studies of complexes 6, 7, 9–12 confirm the ligand's coordination to the metal centre through enolic oxygen (of pyrazolone), azomethine nitrogen and enolic oxygen (hydrazide) atoms. The reactivity of the complexes and their catalytic potential was screened towards their peroxidase mimetic activity in the oxidation of pyragallol in aqueous media with H2O2 as oxidant, showing high activity under mild conditions. They were also tested in the catalytic oxidation of 1‐phenylethanol with H2O2 that yields acetophenone as main product. Parameters such as catalyst and oxidant amount, time, temperature, and solvent effects were optimised for maximum oxidation of 1‐phenylethanol. The complexes show excellent catalytic activity towards oxidation of 1‐phenylethanol being structural and functional models of the vanadate‐dependent haloperoxidases.

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“…Some tetradentate thiosemicarbazones are synthesized by template condensation in the presence of transition metal ions. Many template compounds synthesized from S-alkyl-thiosemicarbazones with iron(III), nickel(II) [9][10][11][12][13][14], zinc(II) [15,16], copper(II), cobalt(II) [1,17,18], vanadyl(IV) [19], and uranyl(VI) [20] ions have been investigated.…”

Section: Introductionmentioning

confidence: 99%

Iron(III), nickel(II) and zinc(II) complexes based on acetophenone-S-methyl-thiosemicarbazone: synthesis, characterization, thermogravimetry, and a structural study

Kurt

Deniz

2015

Journal of Coordination Chemistry

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New complexes, [Fe(L)Cl], [Ni(L)], and [Zn(L)C 2 H 5 OH] (1-3), were synthesized by template reaction of 2-hydroxy-acetophenone-S-methyl-thiosemicarbazone with 2-hydroxy-benzaldehyde. The compounds were characterized by elemental analysis, magnetic measurements, FT-IR, 1 H NMR, UV-visible, and ESI-MS spectra. In these complexes, the ligand is coordinated to the metal ion as dinegatively charged tetradentate chelating agents via the N 2 O 2 donor set. The iron(III) and zinc(II) complexes exhibit square pyramidal geometry whereas the nickel(II) complex has a square planar geometry. The crystal structure of 1, determined by X-ray diffraction method, indicates that 1 crystallizes in the monoclinic space group P21/c with Z = 4. Thermal decompositions of the compounds have been investigated using TGA in air.

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N2O2-complexes of oxovanadium(IV) with 2,2′-dihydroxybenzophenone thiosemicarbazones: Synthesis, EPR and electrochemical studies

Cited by 14 publications

References 39 publications

Oxovanadium(IV) complexes based onS-alkyl-thiosemicarbazidato ligands. Synthesis, characterization, electrochemical, and antioxidant studies

Oxovanadium(IV) complexes based onS-alkyl-thiosemicarbazidato ligands. Synthesis, characterization, electrochemical, and antioxidant studies

Vanadium Complexes Derived from Acetyl Pyrazolone and Hydrazides: Structure, Reactivity, Peroxidase Mimicry and Efficient Catalytic Activity for the Oxidation of 1‐Phenylethanol

Iron(III), nickel(II) and zinc(II) complexes based on acetophenone-S-methyl-thiosemicarbazone: synthesis, characterization, thermogravimetry, and a structural study

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