Spectrophotometric Studies and Analytical Applications of Vanadium(IV) Chelates with 4-(2-Pyridylazo)resorcinol and 1-(2-Pyridylazo)-2-naphthol

Mushran, S. P.; Prakash, Om; Verma, Jyoti

doi:10.1246/bcsj.45.1709

Cited by 14 publications

(4 citation statements)

References 10 publications

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“…Such an oxidation has been observed in other V(IV)-PAR containing systems; [29][30][31] it could be avoided if special precautions are taken: inert atmosphere, 30 low temperature and flushing the solutions with nitrogen. 32 Our present investigations on the vanadium(IV)-PAR-TNBT-water-chloroform system showed that the optimum pH range for extraction of V(IV) is pH = 4.0 to 4.9 ( Figure 3, curve 4), λ max appears at 560 nm (Figure 2, curve 4), and both the molar ratios PAR:V(IV) and TNBT:V(IV) are 2:1. Having in mind the state of V(IV) 33 and PAR 28,34 at the optimum acidity, and the literature 23 we suggest the following scheme of complex formation:…”

Section: Vanadium(iv)-par-mbt-water-chloroform Systemsmentioning

confidence: 59%

“…It should be mentioned that the stability of [Chel] n-in ternary tetrazolim IACs with participation of ADR is sometimes unknown due to the fact that T m+ (in particular MBT 2+ ) could stabilize different anionic species (e.g. with 2:1 ADR/V ratio 10,[20][21][22][23][24]39 ) in comparison to these obtained in aqueous solutions 29,30,32,35 or by extraction with other heavy organic salts. 34,[40][41][42] …”

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confidence: 99%

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Some Ternary Phenylmethoxybis(tetrazolium) Complexes of Vanadium(IV,V) and Their Constants of Association

Gavazov¹,

Racheva²,

Lekova³

et al. 2012

Croat. Chem. Acta

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Abstract. Several liquid-liquid extraction systems containing vanadium {vanadium(IV) or vanadium(V)}, azoderivative of resorcinol {ADR: 4-(2-pyridylazo)-resorcinol (PAR) or 4-(2-thiazolylazo)-resorcinol (TAR)} and (phenylmethoxibis)tetrazolium salts {MBT: 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Blue Tetrazolium, BT) or 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)-bis[2,5-di(4-nitrophenyl)-2H-tetrazolium] chloride (Tetranitroblue Tetrazolium, TNBT)} were studied. The optimum operating conditions and compositions of the extracted species were found. The constants of association (β) between MBT 2+ and the anionic V-ADR chelates (Chel n-) were calculated. Previously reported negative linear relationship between log β and the number of nitro groups included in tetrazolium cation (N nitro ) was discussed taking into account the obtained results and literature data for V-ADR-MBT complexes of the same class, in which MBT is BT or 3,3'-(3,3'-dimetoxy-4,4'-biphenylene)bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium] chloride (Nitroblue Tetrazolium, NBT). (doi: 10.5562/cca1885)

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Section: Vanadium(iv)-par-mbt-water-chloroform Systemsmentioning

confidence: 59%

mentioning

confidence: 99%

Some Ternary Phenylmethoxybis(tetrazolium) Complexes of Vanadium(IV,V) and Their Constants of Association

Gavazov¹,

Racheva²,

Lekova³

et al. 2012

Croat. Chem. Acta

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“…At pH values higher than 3.2 -3.5 (if C V(IV) is in the interval from 10 -5 mol L -1 to 10 -4 mol L -1 ) a neutral V(IV)-form VO(OH) 2 prevails [39]. This form can be stable up to pH 6.3-6.4 [39], provided that precautions are taken to avoid aerial oxidation of V(IV) [37,40].…”

Section: It Is Known That Vo 2+ ([Vo(h 2 O) 5 ]mentioning

confidence: 99%

Ternary complexes of vanadium(IV) with 4-(2-pyridylazo)-resorcinol (PAR) and ditetrazolium chlorides (DTC)

Genç

Gavazov²,

Türkyılmaz

2010

Open Chemistry

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Complex formation and liquid-liquid extraction have been studied for ternary complexes of vanadium(IV) with 4-(2-pyridylazo)-resorcinol (PAR) and ditetrazolium chlorides (DTC) in a water-chloroform medium. The specific ditetrazolium compounds investigated were i) 3,3′-(4,4′-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Neotetrazolium chloride, NTC); ii) 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)-bis(2,5-diphenyl-2H-tetrazolium) chloride (Blue Tetrazolium chloride, BTC); and iii) 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)-bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium] chloride (Nitro Blue Tetrazolium chloride, NBT). Molar absorptivity coefficients and the composition of the complexes have been calculated. Association constants (β) have also been obtained for the interactions between the vanadium(IV) — PAR anionic chelates [VO(PAR)2]2− (I) and [VO(OH)2(PAR)2]4− (II), and ditetrazolium cations (DT2+). Some special features of NBT as an extraction-spectrophotometric reagent for vanadium(IV) have been discussed. Unlike NTC and BTC which form complexes with both I and II, NBT associates only with II. The pH interval for complete extraction of (NBT2+)2[VO(OH)2(PAR)2] is broader and allows work at lower pH values the other ion-associates of V(IV,V)-PAR that were studied. NBT is -therefore the appropriate reagent both for direct V(IV) determination and for V(IV)/V(V) separation. Some additional characteristics for the V(IV)-PAR-NBT-water-chloroform system have been determined: extraction constant, distribution constant, recovery factor, limit of detection and limit of quantification. Beer’s law is valid up to 1.4 μg mL−1 vanadium(IV) with molar absorptivity coefficient of 3.55×104 L mol−1 cm−1 at λmax=559 nm.

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“…In the interpretation of the obtained experimental results, we used information for the complex formation between V IV and ADs in the presence [32][33][34][35] or absence [23,[35][36][37][38] of auxiliary reagents. We suggested several structures of the chromogenic anionic part of the extracted species.…”

Section: Introductionmentioning

confidence: 99%

Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

et al. 2019

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The azo dye 4-(2-thiazolylazo)orcinol (TAO) and the cationic ion-pair reagent 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) were examined as constituents of a water-chloroform extraction-chromogenic system for vanadium(IV). The effects of TAO concentration, TTC concentration, pH and extraction time were examined. Under the optimum conditions the extracted complex has a composition of 1:2:1 (V:TAO:TTC). The absorption maximum, molar absorptivity and constant of extraction were determined to be λmax=544 nm, ε544=1.75×104 dm3 mol–1 cm–1 and Log Kex=4.1. The ground state equilibrium geometries of the possible monoanionic VIV-TAO 1:2 species were optimized by the HF method using 3-21G* basis functions. Their theoretical time dependent electronic spectra were simulated and compared with the experimental spectrum. The best fit was obtained for the structure in which one of the TAO ligands is tridentate, but the other is monodentate (bound to VIV through the oxygen which is in the ortho-position to the azo group) and forms a hydrogen bond N–H...O=V through its protonated heterocyclic nitrogen. Based on this unusual structure, which can explain some peculiarities of the complex formation between VIV and commonly used azo dyes, the ground state equilibrium geometry of the whole ternary 1:2:1 complex was computed at the HF and BLYP levels.

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Spectrophotometric Studies and Analytical Applications of Vanadium(IV) Chelates with 4-(2-Pyridylazo)resorcinol and 1-(2-Pyridylazo)-2-naphthol

Cited by 14 publications

References 10 publications

Some Ternary Phenylmethoxybis(tetrazolium) Complexes of Vanadium(IV,V) and Their Constants of Association

Some Ternary Phenylmethoxybis(tetrazolium) Complexes of Vanadium(IV,V) and Their Constants of Association

Ternary complexes of vanadium(IV) with 4-(2-pyridylazo)-resorcinol (PAR) and ditetrazolium chlorides (DTC)

Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

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