Potentiometric Studies Research Articles

Tailoring CO2 detection capabilities using Co-ZnO/MoS2 nanocomposites through electrolyte concentration modulation

The current study explores a new approach to investigate the CO2 detection capabilities of cobalt-doped zinc oxide (Co-ZnO) combined with molybdenum sulfide (MoS2) hybrid nanomaterials Co-ZnO/MoS2 (CZM). The hydrothermally synthesized CZM composites provide unique structural and compositional properties, with 25 nm as their longest dimension (length), and specific lattice structure. CZM-based electrodes are developed by preparing the nanomaterial-dispersed ink, and potentiometric studies explore the optimal sensing performance. We found significant enhancements in sensitivity, reaction time, and reduction efficiency by systematically changing the electrolyte concentration in the electrode cell. Bode and Nyquist plots explain the influence of electrolyte concentration and the nanomaterial synergy in CO2 sensing and conversion with the 0.1 N electrolyte with the maximum efficiency. By offering important insights into how the electrolyte content affects the performance of Co-ZnO/MoS2 nanocomposite sensors, this study advances the field of CO2 sensing technology. Further, the nanomaterials extend their applicability in environmental monitoring, evaluating indoor air quality, and industrial processes.

A Straightforward Model for Quantifying Local pH Gradients Governing the Oxygen Evolution Reaction.

The production and consumption of protons by an electrocatalyst will, under certain conditions, generate localized microenvironments with properties distinct from those of the bulk solution. These local properties are particularly impactful for reactions involving proton-coupled electron transfer, where the generation of locally basic or acidic environments may significantly influence the energy efficiency and reaction selectivity of the electrocatalyst. Whereas local pH environments have been observed and characterized in reductive half-reactions, including the CO2 reduction and hydrogen evolution reactions, the incompatibility of conventional techniques and materials has limited studies in oxidative half-reactions, including the oxygen evolution reaction (OER), which provides the reducing equivalents for solar-to-fuels electrolysis. With the straightforward parameters bulk pH, buffer composition and pKa, and mass transport, we develop a model for describing local pH as a function of current density regardless of the microscopic details of the mechanism. Using an acid-stable PbOx OER catalyst, we observe the formation and dissipation of pH gradients during the OER and validate the model with voltammetric and potentiometric studies. The model predicts how local acidic environments can develop over a narrow OER current density window, thus providing further motivation for the development of OER catalysts that are stable to acid, even when operating in basic aqueous conditions. More generally, the model is not restricted to the OER and is useful for determining the onset of local pH gradients for other electrocatalytic reactions that involve the consumption or generation of protons in energy conversion reactions.

Evaluation of Stability constant of Binary complex of Tannic Acid with Fe(II) in Aqueous Solution: Potentiometric Study

In this study, the protonation equilibria of the tannic acid was determined and used for determining the stability constants of the binary complexes formed with iron (II) ions in the aqueous medium under the experimental conditions by potentiometric method using Irving and Rossotti equation, where Stability constant was 3.205 for Fe(II)–tannic acid complex, while Fe(II) was formed complexes with tannic acid of various stoichiometries, which in the 1:1 molar ratio at pH = 11.24. Furthermore, the ionic strength and the influence of temperature on the stability of the complexes is investigated, where stability constant in presence 0.1 M NaCl (ionic strength) of binary iron-Tan complex equal 3.254, and at different temperatures were log K1= 3.156 at 298.15 K, log K1 = 3.205 at 310.15 K, and log K1 = 3.256 at 313.15 K.

Thermodynamic Studies of Complexes in Cu(II)/Uridine-5'-Diphosphoglucuronic Acid System.

A binary system of uridine-5'-diphosphoglucuronic acid with copper (II) ions was studied. Potentiometric studies in aqueous solutions using computer data analysis were carried out. The pH of dominance, the overall stability constants (logβ), and the equilibrium constants of the formation reaction (logKe) were determined for each complex compound formed in the studied system. Spectroscopic studies were carried out to determine the mode of coordination in the compounds studied. Cytotoxicity and metabolic activity tests of the compounds obtained showed an increase in the biological activity of the complexes tested against the free ligand. The current research may contribute to the knowledge of complex compounds of biomolecules found in the human body and may also contribute to the characterization of a group of complex compounds with potential anticancer properties.

Experimental and Computational Anticorrosion Behaviors of Pyrazole s-Triazine/anilino-morpholino Derivatives for Steel in Acidic Solutions.

The corrosion inhibition of C-steel by two s-triazine/morpholino-anilino-pyrazole derivatives, namely, 4-(3,5-dimethyl-1H-pyrazol-1-yl)-6-morpholino-N-phenyl-1,3,5-triazin-2-amine (1) and N-(4-bromophenyl)-4-(3,5-dimethyl-1H-pyrazol-1-yl)-6-morpholino-1,3,5-triazin-2-amine (2) was investigated by impedimetric and potentiometric studies. It was found that (1) and (2) acted as cathodic-type corrosion inhibitors that retard the hydrogen evolution reaction. The percent corrosion inhibition, 98.5% for compound (2) (with bromo substituent) at 80 ppm, was slightly higher than 97.8% for (1) at 100 ppm. Thus, the replacement of a -H with -Br substituent increased the corrosion inhibition properties. Compound (2) exhibited Temkin isotherm adsorption, whereas compound (1) exhibited Langmuir adsorption. Scanning electron microscopy (SEM) analysis of the steel surface indicated that the inhibitors caused protection of the surface. The weight loss experiment also proved the decrease in the corrosion rate when inhibitors were added. The difference in inhibitory efficiency between compounds (1) and (2) was investigated by density functional theory (DFT) to study neutral and protonated species in gaseous and aqueous phases. The theoretical analysis demonstrated that compound (2) exhibited higher inhibitory activity on a metal surface compared to compound (1), aligning with the experimental results. The energy associated with the metal/adsorbate arrangement, represented by dE ads/dNi , was higher for (2) (-380.91 kcal mol-1) compared to (1) (-371.64 kcal mol-1). This indicated better adsorption of (2) over (1).

Potentiometric Studies on Ion-Transport Selectivity in Charged Gold Nanotubes.

Under ideal conditions, nanotubes with a fixed negative tube-wall charge will reject anions and transport-only cations. Because many proposed nanofluidic devices are optimized in this ideally cation-permselective state, it is important to know the experimental conditions that produce ideal responses. A parameter called Ccrit, the highest salt concentration in a contacting solution that still produces ideal cation permselectivity, is of particular importance. Pioneering potentiometric studies on gold nanotubes were interpreted using an electrostatic model that states that Ccrit should occur when the Debye length in the contacting salt solution becomes equivalent to the tube radius. Since this "double-layer overlap model" (DLOM), treats all same-charge ions as identical point charges, it predicts that all same-charged cations should produce the same Ccrit. However, the effect of cation on Ccrit in gold nanotubes was never investigated. This knowledge gap has become important because recent studies with a polymeric cation-permselective nanopore membrane showed that DLOM failed for every cation studied. To resolve this issue, we conducted potentiometric studies on the effect of salt cation on Ccrit for a 10 nm diameter gold nanotube membrane. Ccrit for all cations studied were, within experimental error, the same and identical, with values predicted by DLOM. The reason DLOM prevailed for the gold nanotubes but failed for the polymeric nanopores stems from the chemical difference between the fixed negative charges of these two membranes.

Subsurface flow pathway and hydrochemistry of a geographically isolated depression wetland in the Serra Geral Diabase Formation, São Paulo State, Brazil

Connectivity among water bodies is crucial for hydrological and ecological processes and fundamental for water management. Hydrochemistry and potentiometric studies on an isolated wetland allow to assess landscape influence, flow pathways, and subsurface connection. This study focuses on an isolated wetland over diabase on a topographic depression, with no visible river connection, and aims to determine the influence of rainfall and landscape on water composition and investigate subsurface flow toward the Santa Gertrudes stream. Water levels were monitored, and samples were collected from four wells during wet and dry seasons. Physical and chemical water parameters were measured, and ion concentrations determined. Pearson’s correlations highlighted codependence between physical and chemical parameters and ions and Piper’s diagram classified water composition. Six potentiometric maps were generated using interpolated hydraulic loads from monitoring campaigns. The findings show fluctuations in water level (0.11 to 0.93 m during wet periods and 1.25 to 1.79 m during dry periods), indicating rainwater directly affects water availability. Water composition was categorized as Sodium Bicarbonate and electrical conductivity values (greater than 100 µS/cm) may indicate that upstream wells are retaining salts from the surrounding crops. Strong positive correlation between sodium, bicarbonate and carbonate, and sulfate with electrical conductivity suggests simultaneous release of ions due to rock and soil mineral alteration. Potentiometric data reinforce the hypothesis of a subsurface connection between the studied area and the Santa Gertrudes stream. Future studies could benefit from expanding the monitoring network to include more GIWs and applying additional methods, such as isotope tracers.

Fabrication of molybdenum disulphide / carbon paste (MoS2/CP) nanocomposite as a modified platinum electrode for electrocatalytic oxidation of benzyl alcohol in biphasic electrolysis

Alcohol to aldehyde conversion is a significant industrial process. Herein, we developed the biphasic method for converting the alcohols to aldehydes and ketones in the presence of potassium iodate as an electrocatalytic mediator. This transformation is obtained after 3.5 h at room temperature using the Platinum (Pt) metal electrodes decorated with molybdenum disulphide (MoS2) and Carbon Paste (CP). A thin layer of MoS2 and CP helps to evenly deposit the Pt metal onto the surface, resulting in a significant surface improvement. The electrochemical properties of the modified platinum electrodes were analyzed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The physicochemical properties of the modified electrodes were studied by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. This method has been applied to the electrochemical oxidation of benzyl alcohol via interphasic in iodate free radicals. The cyclic potentiometric studies showed the electrocatalytic activity of the Pt-MoS2-CP electrode was higher than the Pt–MoS2 electrode in terms of the ability to convert benzyl alcohol to benzaldehyde. High electrocatalytic activity, rapid current response, and stable catalytic activity were all characteristics of the chemically modified electrode.

Exo- or endo-1H-pyrazole metal coordination modulated by the polyamine chain length in [1 + 1] condensation azamacrocycles. Binuclear complexes with remarkable SOD activity.

The Cu2+ complexes of three [1 + 1] azacyclophane macrocycles having the 1H-pyrazole ring as the spacer and the pentaamine 1,5,8,11,15-pentaazadecane (L1) or hexaamines 1,5,8,12,15,19-hexaazanonadecane (L2) and 1,5,9,13,17,21-hexaazaheneicosane (L3) as bridges show endo- coordination of the pyrazolate bridge giving rise to discrete monomeric species. Previously reported pyrazolacyclophanes evidenced, however, exo-coordination with the formation of dimeric species of 2 : 2, 3 : 2 or even 4 : 2 Cu2+ : L stoichiometry. The complexes have been characterized in solution using potentiometric studies, UV-Vis spectroscopy, paramagnetic NMR, cyclic voltammetry and mass spectrometry. The measurements show that all three ligands have as many protonation steps in water as secondary amines are in the bridge, while they are able to form both mono- and binuclear Cu2+ species. The crystal structures of the complexes [Cu(HL1)Br]Br(1+x)(ClO4)(1-x)·yH2O (1) and [Cu2(H-1L2)Cl(ClO4)](ClO4)·H2O·C2H5OH (2) have been solved by X-ray diffraction studies. In 1 the metal ion lies at one side of the macrocyclic cavity being coordinated by one nitrogen of the pyrazolate moiety and the three consecutive nitrogen atoms of the polyamine bridge. The other nitrogen of the pyrazole ring is hydrogen-bonded to an amine group. In 2 the two metal ions are interconnected by a pyrazolate bis(monodentate) moiety and complete their coordination spheres with three amines and either a bromide or a perchlorate anion, which occupy the axial positions of distorted square pyramid geometries. Paramagnetic NMR studies of the binuclear complexes confirm the coordination pattern observed in the crystal structures. Cyclic voltamperommetry data show potentials within the adequate range to exhibit superoxide dismutase (SOD) activity. The IC50 values calculated by McCord-Fridovich enzymatic assays show that the binuclear Cu2+ complexes of L2 and L3 have SOD activities that rank amongst the highest ones reported so far.

Simple potentiometry and cyclic voltammetry techniques for sensing Hg2+ ions in water using a promising flower-shaped WS2-WO3/poly-2-aminobenzene-1-thiol nanocomposite thin film electrode.

A highly promising flower-shaped WS2-WO3/poly-2-aminobenzene-1-thiol (P2ABT) nanocomposite was successfully synthesized via a reaction involving 2-aminobenzene-1-thiol, Na2WO4, and K2S2O8 as oxidants. The WS2-WO3/P2ABT nanocomposite demonstrated remarkable potential as a sensor for detecting harmful Hg2+ ions in aqueous solutions. The sensing behavior was evaluated over a wide concentration range, from 10-6 to 10-1 M, using a simple potentiometric study on a two-electrode cell. The calibration curve yielded an excellent Nernstian slope of 33.0 mV decade-1. To further validate the sensing capabilities, cyclic voltammetry was employed, and the results showed an increasing trend in the cyclic voltammetry curve as the Hg2+ concentration increased from 10-6 to 10-1 M with an evaluated sensitivity of 2.4 μA M-1. The WS2-WO3/P2ABT nanocomposite sensor exhibited exceptional selectivity for detecting Hg2+ ions, as no significant effects were observed from other interfering ions such as Zn2+, Ni2+, Ca2+, Mg2+, Al3+, and K+ ions in the cyclic voltammetry tests. Furthermore, the sensor was tested on a natural sample that was free of Hg2+ ions, and the cyclic voltammetry curves did not produce any characteristic peaks, confirming the sensor's specificity for Hg2+ detection. The sensor's cost-effectiveness and ease of fabrication present the potential for developing a simple and practical sensor for detecting highly poisonous ions in aqueous solutions.

Potentiometric Study of the Dissociation Constants of Some Schiff Bases from ortho-Hydroxynaphthaldehyde and 2,4-Substituted Aniline and Stability Constants of Their Cu(II) Complexes in Mixed Solvents

Potentiometric Study of the Dissociation Constants of Some Schiff Bases from ortho-Hydroxynaphthaldehyde and 2,4-Substituted Aniline and Stability Constants of Their Cu(II) Complexes in Mixed Solvents

A New Approach for Increasing the Chelating Capacity of the Tartrate Ion in the Extraction of Copper from Ores

The role of the tartrate ion in the extraction of copper from oxidized ore in aqueous alkaline medium is first reported. This was demonstrated by a sequential evaluation of the following: (i) The formation of an ionic complex resulting from the interaction of copper salts (CuSO4, Cu(NO3)2) with an alkaline aqueous solution of tartrate ions. (ii) The treatment of metallic copper with hydrogen peroxide. (iii) Spectrophotometric and potentiometric studies of malaquite. These studies demonstrated that the Cu(II)–tartrate interaction is only possible due to the chelating activity of tartrate ion leading to the formation of the [Cu(OH)2C4H4O6]2− anion complex and the lixiviation of the oxidized mineral is controlled by the chelating agent. The advantage of this approach relative to previous ones is discussed. Final conclusions are given.

NiFe Alloy Nanoparticles Tuning the Structure, Magnetism, and Application for Oxygen Evolution Reaction Catalysis

In this study, Ni-Fe alloy nanoparticles were prepared using the proteic sol–gel method, followed by a reduction in H2 at 500 and 700 °C, namely hereafter as NiFe-500 and NiFe-700, respectively. The morphological, structural, and magnetic properties were tuned via the thermal treatment in H2. The samples were studied using XPS, TEM, Mössbauer spectroscopy, DC magnetic measurements, and electrochemical measurements. Ritveld refinements showed that the sample NiFe-500 has FCC (face-centered cubic) and BCC (body-centered cubic) NiFe alloys, while the sample NiFe-700 has only FCC NiFe alloy. For both samples, magnetization measurements in the range of 300–900 K showed the presence of the Griffiths phase, indicating the formation of clusters of either Fe or Ni-Fe alloys rich in Fe. The sample NiFe-500 presented ferromagnetic (FM) transitions at 533, 700, and 834 K, assigned to the alloys Ni37Fe63-FCC, Ni46Fe54-FCC, and Ni55Fe45-FCC, respectively. In contrast, we could not observe the FM transition of the BCC Ni-Fe alloy because of limitations in our experimental setup (T ≤ 900 K). Meanwhile, three FM transitions were observed for the sample NiFe-700 at 480, 655, and 825 K, attributed to the alloys Ni34Fe66-FCC, Ni43Fe57-FCC, and Ni54Fe46-FCC, respectively. At 5 K, the samples NiFe-500 and NiFe-700 have saturation magnetizations of 164.2 and 173.6 emu g−1, respectively. For application in Oxygen Evolution Reaction catalysis, the samples NiFe-500 and NiFe-700 showed different overpotentials of 319 and 307 mV at 10 mA cm−2. These low overpotential values indicate a higher electrochemical activity of the FCC Ni-Fe alloy and, for both samples, a superior electrocatalytic activity in comparison to RuO2 e IrO2 conventional catalysts. Furthermore, the samples showed high electrochemical stability in chrono potentiometric studies for up to 15 h. This current work highlights that the Ni-Fe alloys produced via the proteic sol–gel and with a reduction in H2 methods can be promising for OER systems due to their good performance and low costs.

Valorization of citrus waste for circular economy: A case study on bergamot pomace as sorbent for Cd2+ removal and source of added value compounds

The potential of bergamot pomace for the development of materials able to efficiently remove cadmium(II) from water and for the recovery of bioactive compounds has been explored. To this purpose, raw bergamot waste resulting after industrial essential oil and juice extraction was mechanically ground, desiccated, pretreated with various chemicals (e.g. NaOH, HNO3, H2O2, H2O, 2-propanol) and dried up to constant weight thus affording solid samples that were characterized by ATR FT-IR spectroscopy. The solutions recovered after the pomace pretreatments were investigated by means of HPLC in combination with PDA and MS detectors to assess the residual content of bioactive components, e.g., phenolic and oxygenated heterocyclic compounds (OHCs). Potentiometric studies were performed on suspensions at t = 25 °C, I = 0.10 mol dm−3 in NaNO3(aq) to investigate pomace acid-base properties and binding ability towards Cd2+ ions. Sorption efficiency was investigated by means of kinetic and isotherm batch experiments and resulted to be 92 ± 7 mg g−1. Once loaded, sorbent reusability was tested by performing metal stripping cycles using various desorbents (HCl, HNO3, L-GLDA, S,S-EDDS, EDTA) with an efficiency of ∼ 60% after one cycle. The equilibrium Cd2+ concentration in solution was determined by differential pulse voltammetry and ICP-OES.

Potentiometric Studies on Binary and Ternary Complexes of Ni(II) and Cu(II) Ions with L-Valine and Paracetamol

The protonation constants of the free ligands and the stability constants of binary and ternary complexes of bivalent metal ions of Ni(II) and Cu(II) with a biologically important amino acid of L-valine, Val, and paracetamol, Para, were studied potentiometrically in aqueous solutions at 313.15 ± 0.1 K and a fixed ionic strength of I = 0.10 M NaCl. The complexation model for each system was established using the Irving-Rossotti equation. The formation of the 1:2 or 1:1 binary complexes and 1:1:1 ternary complexes in which the amino acid Val was used as the primary ligand and Para as the secondary ligand, as inferred from the corresponding potentiometric pH-metric titration curves, and their relative stabilities compared to the corresponding ML and ML2 binary complexes are expressed in terms of statistical parameters ∆logK, logK1 and logK2. The complex stability was found to follow the order of Cu(II) > Ni(II). Through these diagnostic studies, it was possible to give the general formula of compounds prepared from amino acids and paracetamol. Amino acid binds to the central ion through oxygen in the hydroxyl group and nitrogen atom in the amine group (-NH2), whereas paracetamol forms a unipolar bond by binding to the concentrated ion through the oxygen atom in the hydroxyl group. Most of the nickel complexes had octahedral symmetry with valine and paracetamol ligands, while the copper complexes had square or hierarchical to square base symmetry.

Semi-empirical calculations and potentiometric studies on complexation equilibria of 2,2’-Bipyridyl in SDS and TBAB micellar media

Chemical speciation of Cu(II) complexes of 2,2-Bipyridyl in the of the presence of different- surfactant media (TBAB and SDS) has been studied pH metrically. The models containing different kinds of species were refined using the computer program, MINIQUAD75 and formation constants were determined. The predominant species detected were Cu(bipyH) and Cu(bipy)2 in both surfactant media. It was found that the formation constant is more in SDS compared to TBAB and aqueous media because the proton association is more in the anionic micellar medium. Binding energies and HOMO-LUMO energy gaps were calculated from semi-empirical studies based on PM6 method. It was found that Cu(bipy)2 is more stable than Cu(bipy) and Cu(bipyH+).

Potentiometric Study of the Dissociation and the Metal Complex-formation Competence of 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (Dacarbazine).

A potentiometric investigation has been carried out to disclose the coordination properties of Dacarbazine, 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (abbreviated DTIC) with particular transition metal ions (Zn2+, Cu2+, Ni2+ and Co2+). The coordination of DTIC with these metal ions results in several complexes emerging in solution. The aim of this work is to determine the protonation constants of the DTIC and to show the extent of its coordination with (Zn2+, Cu2+, Ni2+ and Co2+), in other words, establish the stability of the complexes formed between the DTIC and these metal ions by the determination of their stability constants. Experimental environments were organized to attain the coordination and measurements in aqueous solutions at 25±0.1 ºC and an ionic background of 0.1 mol.dm-3 NaCl. The HYPERQUAD computer program was used to determine both the protonation and stability constants for the ligand and metal-ligand complexes respectively. DTIC has five protonation constants that can be obtained under experimental conditions used; 10.54, 20.15, 26.99, 32.02 and 36.01. The results are interpreted in terms of the basicity of the donor atoms and structural composition of the ligand. All the complexes produced in the solution are exhibited in speciation diagrams.

A New Family of Macrocyclic Polyamino Biphenolic Ligands: Acid-Base Study, Zn(II) Coordination and Glyphosate/AMPA Binding

In this study, the ligands 23,24-dihydroxy-3,6,9,12-tetraazatricyclo[17.3.1.1(14,18)]eicosatetra-1(23),14,16,18(24),19,21-hexaene, L1, and 26,27-dihidroxy-3,6,9,12,15-pentaazatricyclo[20.3.1.1(17,21)]eicosaepta-1(26),17,19,21(27),22,24-hexaene, L2, were synthesized: they represent a new class of molecules containing a biphenol unit inserted into a macrocyclic polyamine fragment. The previously synthesized L2 is obtained herein with a more advantageous procedure. The acid-base and Zn(II)-binding properties of L1 and L2 were investigated through potentiometric, UV-Vis, and fluorescence studies, revealing their possible use as chemosensors of H+ and Zn(II). The new peculiar design of L1 and L2 afforded the formation in an aqueous solution of stable Zn(II) mono (LogK 12.14 and 12.98 for L1 and L2, respectively) and dinuclear (LogK 10.16 for L2) complexes, which can be in turn exploited as metallo-receptors for the binding of external guests, such as the popular herbicide glyphosate (N-(phosphonomethyl)glycine, PMG) and its primary metabolite, the aminomethylphosphonic acid (AMPA). Potentiometric studies revealed that PMG forms more stable complexes than AMPA with both L1- and L2-Zn(II) complexes, moreover PMG showed higher affinity for L2 than for L1. Fluorescence studies showed instead that the L1-Zn(II) complex could signal the presence of AMPA through a partial quenching of the fluorescence emission. These studies unveiled therefore the utility of polyamino-phenolic ligands in the design of promising metallo-receptors for elusive environmental targets.

Derivatives of cyclam-1,8-diacetic acid: Synthesis and complexes with divalent transition metal ions

1,4,8,11-tetraazacyclotetradecane-1,8-diacetatic acid, H2te2a, and series of its derivative bearing two substituted N-benzyl groups were synthesized and their complexes were studied. Series of CoII and ZnII complexes was prepared in the solid-state and X-ray diffraction analysis showed that the metal ions are hexacoordinated by four nitrogen atoms of the macrocycle and two oxygen atoms of the carboxylate pendants. The two oxygen atoms were in cis and trans mutual position in the CoII and ZnII complexes, respectively. Potentiometric study of CoII, ZnII, CuII and NiII-H2te2a systems showed that the complexes are highly thermodynamically stable and the ligand is selective for CuII ions (logK = 27.5) over the other ions (logK = 21–22). UV-VIS and electrochemical data for the CoII-H2te2a system showed that complexation was rather slow (several hours at pH 4.5, 25 °C) and the complex undergoes slow oxidation with air oxygen.

Potentiometric Study of Complexation in a Copper(II)–1-Phenyl-2,3-dimethylpyrazoline-5-thione–Hydrochloric Acid–Acetone System

Potentiometric Study of Complexation in a Copper(II)–1-Phenyl-2,3-dimethylpyrazoline-5-thione–Hydrochloric Acid–Acetone System