Liquid-Liquid Extraction-Spectrophotometric Investigations of Three Ternary Complexes of Vanadium(V)

Abstract

Abstract. Complex formation and liquid-liquid extraction (LLE) were studied in systems containing vanadium(V), 5-methyl-4-(2-thiazolylazo)resorcinol (TAO), tetrazolium salt (TZS), water and chloroform. The following three TZSs were used: 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT), 3-(2-naphtyl)-2,5-diphenyl-2H-tetrazolium chloride (Tetrazolium violet, TV), and 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT). Concentration of the reagents (TAO and TZS), pH of the aqueous medium, and shaking time were subjects of optimization experiments. Formation of ternary complexes with a composition of 2:2:2 was demonstrated by a set of different methods. Some key characteristics concerning the analytical application of the studied LLE-chromogenic systems were established as well.

Preconcentration and Determination of Trace Vanadium(V) in Beverages by Combination of Ultrasound Assisted-cloud Point Extraction with Spectrophotometry

“…, and then formed ion-pairing complexes with hydrophobic amines , o-, m-and p-toluidine derivatives (as R-NH 3 + ) detected by both spectrophotometry and ESR spectrometry. 44 Moreover, so as to support the mechanism of complex formation, from potentiometric titration data obtained in two separate studies, 45,46 including other studies based on ion-association, 47,48 it has been observed that pK a value of chelate complex formed between vanadyl ion, VO 2+ and pyrogallol at pHs near to neutral is 5.40 where it spontaneously forms a highly stable complex with a logK f ranging from 22.97 to 21.68 at pHs near to neutral, gradually decreasing with increasing temperature in range of 25-45 °C. Also, under optimal conditions, it has been ob-served that after pre-reduction and hydrolysis in absence and presence of safranin T as ion pair, vanadium is complexed with pyrogallol in form of anionic VO(OH)L 2 with a logK f of 20.9 with relative error of -3.6% at pH 6.0, and then extracted as the hydrophobic ternary complex in form of VO(OH)L 2 SF into the micellar phase with stoichiometric ratios 1:2 and 1:2:1, as determined using the molar ratio and Job's continuous variation methods.…”

A 2:2:2 Complex of Vanadium(V) with 4-(2-Thiazolylazo)orcinol and 2,3,5-Triphenyl-2H-Tetrazolium Chloride

“…5,6,9,10 The following ACs were investigated as components of ternary V(V)-AC-TZ complexes: 4-(2-pyridylazo)resorcinol 10-12 , 4-(2-thiazolylazo)resorcinol, 13,14 and 4-(2-thiazolylazo)orcinol (TAO). 15 The obtained results show that the V(V):AC molar ratio in these complexes differs, [11][12][13][14][15] as a rule, from the typical 1:1 ratio established in the presence of other ion-association reagents (Table S1). However, the reason for this peculiarity is unclear and quantum-chemical calculations on V-AC-TZ ternary complexes have never been conducted.…”

“…sar-Boltz method 35 ( Figure 6), extended by the equation 5, proposed in our previous paper 15 for this kind of complexes.…”

“…It is shifted to 5 nm as compared to the maximum of the binary V(V)-TAO complex in water-ethanol medium (λ = 550 nm) 16 and practically coincides with that of other complexes of the type V(V)-TAO-TZ in chloroform studied in our previous paper. 15 It should be mentioned that the position of this maximum is constant independently of changes in pH and concentrations of the reagents. The optimum LLE-spectrophotometric conditions are given in Table 1.…”

Extraction-Chromogenic System for Nickel(II) Based on 5-methyl-4-(2-thiazolylazo)resorcinol and Aliquat 336

“…[21][22][23][24][25][26][27][28] It has recently been used in our laboratory for LLE of V IV,V . [29][30][31][32] Here, we describe investigations on a LLE-chromogenic system for Ni II containing MTAR and the ionic liquid Aliquat 336 (A336). The selected organic solvent was isobutanol (2-methylpropan-1-ol).…”