A novel copper(II) complex based on N-2-(2-pyridyl)ethyl-2-aminoethanesulfonic acid is prepared, its structure is studied by XRD (CCDC No. 2215117). The crystal of the complex is formed by monomeric [CuLH2O]NO3 units. The metal centers of the units have an octahedral coordination environment formed by nitrogen atoms of pyridine and the amino group, oxygen atoms of the sulfo group, and water molecules located in the equatorial plane. On the axial axis, there are oxygen atoms of the sulfo groups of the neighboring ligands forming a 1D coordination polymer.

A method for preparation of poly(N-sulfoethylaminomethylstyrene) with a degree of functionalization up to 0.54 has been developed. The composition and structure of the products of polymer analogous transformations were characterized by elemental analysis, FTIR spectroscopy, and thermogravimetric analysis. It has been established that materials with a degree of functionalization of 0.35 and 0.5 are capable of selective sorption of noble metal ions in the presence of transition metals. An increase in the sulfoethyl group content increases the degree of extraction of PdII and reduces the degree of extraction of PtIV. It was also found that the studied sorbent with a degree of functionalization of 0.35 selectively extracts AgI ions from multicomponent systems at pH 5.5–6.0 in an ammonium acetate buffer solution.

The work deals with the development of an approach to the determination of chlortetracycline, which combines the preconcentration of the analyte with its subsequent determination by capillary zone electrophoresis. The conditions that ensure the lowest value of the limit of determination for chlortetracycline in aqueous solutions using a Kapel-105M capillary electrophoresis system (Lumex, Russia) are determined, i.e., temperature, time and pressure of sample injection, background electrolyte composition, and detection wavelength. It is shown that the stability of a chlortetracycline solution is maximum at a storage temperature of 0.5°С in the absence of buffer systems or in using a dilute ammonium acetate buffer solution. It is found that the recovery of chlortetracycline by strongly acidic cation exchangers KU-1, KU-2 is higher compared to that by KB-4 and KB-4P2, bearing weakly acidic functional groups. The conditions under which the recovery of the analyte by KU-1 from a phosphate buffer solution is about 90% are determined.

Синтезирован новый комплекс меди(II) на основе N-2-(2-пиридил)этил-2-аминоэтансульфокислоты и изучено его строение методом рентгеноструктурного анализа (депозит CCDC № 2215117). Кристалл комплекса образован мономерными звеньями состава [CuLH2O]NO3, в которых октаэдрическое координационное окружение металлоцентра формируется атомами азота пиридина и аминогруппы, атомами кислорода сульфогруппы и молекулы воды, располагающимися в экваториальной плоскости. На аксиальной оси находятся атомы кислорода сульфогрупп соседних лигандов, которые формируют 1D координационный полимер.

Sorption properties of thiocarbamoylated polyethylene toward silver(I) from multicomponent solutions have been studied. The synthesized sorbent has been found to exhibit a high sorption capacity and selectivity toward silver ions. In static sorption mode, quantitative extraction is possible from solutions with Ag(I) concentration of 1 × 10–4 mol/L in pH range from 1 to 7, concomitant Ca(II), Mg(II), Cu(II), Fe(III), Zn(II), Cd(II), Ni(II), Mn(II), Co(II), and Pb(II) have no effect on the recovery degree of silver ions. High sorption selectivity retains under dynamic conditions in the presence of excess amounts of base metal ions at pH 2. Full dynamic sorption capacity for silver is 0.35 mmol/g (solution flow rate 2 mL/min, pH 2, sorbent weight 0.1 g, C_Ag^ + = 1 × 10–4 mol/L). The composition of eluents to provide the highest values of silver desorption degree from sorbent surface has been determined. It has been found that the silver capacity of the sorbent slightly decreases after sorption–desorption stage.

New N -derivatives of taurine, N -[2-(2-pyridyl)ethyl]taurine (HL 1 ) and N -[2-(4-pyridyl)ethyl]taurine (HL 2 ) have been synthesized. Using the method of alkalimetric titration of aqueous solutions with pH potentiometric indication at I = 0.1 mol/L (KCl/KNO 3 ) and T = 25 ± 1°C, the acid dissociation constants of functional groups in the composition of reagents have been determined (HL 1 : p K a0 = 3.80 ± 0.03, p K a1 = 8.67 ± 0.02, HL 2 : p K a0 = 4.80 ± 0.05, p K a1 = 8.18 ± 0.04). It has been found that reagent HL 1 is more resistant to the degradation process. The complexation of transition and alkaline earth metal ions with НL 1 has been studied. It has been shown that the introduction of a 2-(2-pyridyl)ethyl substituent into the structure of taurine leads to a significant increase in the stability (Δ log β ≥ 1) of copper(II), cobalt(II), nickel(II), zinc(II), cadmium(II) and silver(I) complexes with НL 1 . Calcium(II), magnesium(II), strontium(II), and barium(II) complexes with HL 1 are characterized by a slight increase in stability (Δ lg β < 1) compared to taurine. Based on the data obtained, the structure of the studied complexes have been assumed.

A new homometallic cubane-like nickel(II) complex based on N -2-(2-pyridyl)ethyl-2-aminoethanesulfonic acid [Ni 4 L 4 (OH) 4 ]·2H 2 O ( I ) is synthesized, and its structure is studied by X-ray diffraction (XRD) (CIF file CCDC no. 2211359). In crystals of the complex, the metallocenters are joined into tetrahedra with the Ni…Ni distances (3.144–3.201 Å) supplemented to cubanes by the μ 3 -bridging oxygen atoms of the hydroxy groups. The coordination environment of each metallocenter is a distorted octahedron. The ligand is deprotonated, exists in the facial conformation, and performs the tridentate function to form two six-membered conjugated chelate cycles.

The paper presents data on the synthesis and study of the acid–base and complexing properties of N -hydroxyalkyl taurine derivatives. The ammonium group dissociation constants of the reagents were determined. The complex formation of taurine derivatives with transition and alkaline-earth metal ions was studied. Trends in the influence of the structure of ligands on the stability constants of their transition and alkaline-earth metal complexes were elucidated. In most cases, the studied ligands form most stable complexes with copper(II) ions. The decrease in amino group basicity in response to the incorporation of additional hydroxyl and/or sulfoethyl groups into a derivative leads to the differentiation of the ligand properties toward the studied ions. The data of this work can help expand the application range of the studied ligands, which can potentially be used as components of buffer solutions where there is the need to avoid or minimize complex formation in solution.

A method for determination of polyorganosiloxanes (by silicon) in water using high-resolution continuum source electrothermal atomic absorption spectrometry with the preliminary extraction of the analytes from the analyzed sample by benzene is proposed. The parameters of the time–temperature program of an atomizer are optimized using a storm water sample. To eliminate chemical interference during the determination of silicon, graphite cuvettes have been modified with a permanent modifier (sodium tungstate) to form a carbide coating. The thermal stabilization of silicon in a graphite furnace has been achieved in the presence of a mixed palladium–magnesium modifier in the nitrate form. The developed method of analysis has been used to determine the content of polyorganosiloxanes (by silicon) in natural water samples. The metrological characteristics of the method in the determined silicon content range of 0.01–100 mg/dm3 have been estimated.

Complex formation of aqua palladium(II) ions with glycine (Gly), β‑alanine (β-Ala), and taurine (Tau) in aqueous solution was studied by spectrophotometric titration at I = 1.0 mol/L (HClO 4 + NaClO 4 ) and T = 25 ± 1°C. A monoligand complex appeared at pH 0 in the H‒Pd–Gly system under the conditions of our experiment; mono- and biscomplexes were formed at pH 1. In the H‒Pd‒β-Ala system, a monoligand complex was formed at pH 1 and mono- and biscomplexes were formed at pH 2. In the H‒Pd‒Tau system, a monoligand complex was formed at pH 1 and 2. Molar absorption coefficients were calculated: the peak absorption occurs at λ = 370 nm and ε = 203 L/(mol cm) for the monoligand glycinate complex [PdGly(H 2 O) 2 ] + ; at λ = 325 nm and ε = 274 L/(mol cm) for the biscomplex [PdGly 2 ] 0 ; at λ = 365 nm and ε = 342 and 297 L/(mol cm) for the β ‑ alaninate [Pdβ ‑ Ala(H 2 O) 2 ] + and taurinate [PdTau(H 2 O) 2 ] + monoligand complexes, respectively; and at λ = 330 nm and ε = 549 L/(mol cm) for the β ‑ alaninate biscomplex [Pdβ ‑ Ala 2 ] 0 . Logarithmic concentration formation constants were calculated for glycinate (log β 1 = 15.03 ± 0.07, and log β 2 = 28.97 ± 0.28), β-alaninate (log β 1 = 13.94 ± 0.05, and log β 2 = 25.24 ± 0.06), and taurinate (log β 1 = 9.74 ± 0.08) palladium(II) complexes.

Sorption properties of poly(3-aminopropylsilsesquioxanes) modified with thiourea groups were studied to predict the possibility of using poly(n-thiocarbamoyl-3-aminopropylsilsesquioxanes) (TCPS) in separation and concentration techniques. The sorbents were synthesized by the sol-gel method followed by solid-phase modification using ammonium thiocyanate or thiosemicarbazide as modifiers. It was established that sorbents with the highest content of thiocarbamide functional groups (modified with ammonium thiocyanate) enabled quantitative and selective recovery of Ag (I) from strongly acidic solutions. The degree of Ag (I) recovery slightly decreases at pH>5, which is associated with increasing competitive sorption of Cu (II), Ca (II), Mg (II), Mn (II) and Fe (III). The highest recovery of Ag (I) for TCPS-0.63 and TCPS-0.68 was achieved at pH ranging from 4 to 8 (degree of recovery was 55–68% (TCPS-0.63); 21–26% (TCPS-0.68 )); at the same time, there was a predominance of competitive sorption of Ca (II), Mg (II), Mn (II), and Fe (III). Based on the aforementioned, it can be concluded that the sorbents modified with ammonium thiocyanate are characterized by high concentration of attached thiocarbamide groups that make them suitable for the selective recovery of Ag (I) ions from multicomponent solutions at pH 1–2.

Министерство науки и высшего образования Российской Федерации Российская академия наук Научный совет по неорганической химии РАН Научный совет по аналитической химии РАН Научный совет по химической технологии РАН Российское химическое общество имени Д.И

The accumulation of electronic waste (e-waste) on the ground leads to environmental pollution with toxic metal ions, which subsequently harms all living organisms. Many countries still use hydrometallurgical or manual methods to extract silver ions from e-waste. These methods are unsustainable and highly toxic; therefore, it becomes necessary to introduce new environmentally compatible methods for separating valuable components from objects of various compositions. This article proposes an environmentally compatible method for the extraction of silver ions from multicomponent systems using poly(N-thiocarbamoyl‑3-aminopropylsilsesquioxane). The sorbent surface was studied by Fourier-transform infrared spectroscopy using an attenuated total internal reflection accessory. The concentration of grafted thiourea groups is 1.39 mmol/g according to elemental analysis. It has been determined that this sorbent is capable of quantitatively extracting silver ions in the pH range from 0 to 6 at a concentration of silver ions in the initial solution of 1·10–4 mol/dm3; the static sorption capacity for silver ions under experimental conditions reaches 1.22 mmol/g. When sorption is carried out in dynamic mode, the value of the dynamic capacity before breakthrough is 0.046 mmol/g, and the value of the total dynamic capacity for silver ions is 0.132 mmol/g. The highest desorption (71–78 %) is achieved using sulfuric acid solutions with a thiourea concentration gradient.

The influence of the mineral composition of water on the results of silicon determination by high-resolution atomic absorption spectrometry with a continuous spectrum source (HR-CS-ETAAS) and electrothermal atomization technique using a contrAA 700 spectrometer has been studied. The study was conducted using samples of natural water from different regions of the Russian Federation and model solutions. A low degree of silicon atomization was recorded when analyzing samples with a complex matrix against the background of a strong absorption signal of matrix components. The reason for the non-selective absorption of the sample matrix by chemical compounds has been demonstrated using a water sample with the most complex composition and a total hardness of about 2000 °dH. The effect of soluble salts of Ca (II) and Mg (II) in the presence of macrocomponents — alkali metal ions K (I) and Na(I) — on the determination of silicon in water has been proved. It is shown that at the values of the total stiffness less than 15 °dH there is no dependence of the analytical signal on the content of matrix components. An assumption is made about the strong influence of calcium compounds on the determination of the analyte due to the formation of a carbide coating on the surface of a graphite furnace, the appearance of a «memory effect» and an increase in the background signal during subsequent atomization cycles. The best results of the silicon determination were obtained with tungsten, iron, magnesium, and palladium present as chemical modifiers. A method of diluting the sample solution was used to reduce the level of background absorption during electrothermal atomization of mineral water. Conditions for eliminating the influence of matrix components for real samples of mineral water and calibration solutions are proposed. A method for determination of the dissolved forms of silicon in water samples with a complex matrix has been developed. The correctness of the results of silicon determination in the samples of natural underground water in the case of a strong matrix effect was confirmed by an independent method of analysis. The results of the study reveal the entirely new prospects of using the method of high-resolution electrothermal atomic absorption spectrometry with a continuous spectrum source for the determination of silicon in natural water.

Protolytic and complexing properties of N-[1,1-bis(hydroxymethyl)ethyl]- and N-[tris-(hydroxymethyl)methyl]-β-alanine were estimated using the potentiometry. Values of the dissociation constants of amino and carboxyl functional groups in molecules of these reagents, as well as the stability constants of their complexes of various compositions with copper(ii), cobalt(ii), nickel(ii), zinc(ii), cadmium(ii), silver(i), magnesium(ii), calcium(ii), strontium(ii), and barium(ii) ions, were calculated. The hydroxyalkylation of β-alanine tunes its properties towards the considered metal ions. Complexes of copper(ii) ions with these β-alanine derivatives are the most stable complex compounds among explored herein.

The sorption kinetics of selected metal ions from multicomponent solutions by sorbents with taurine functions based on aminopolymers, namely, on chitosan, polyallylamine, and polyethyleneimine, has been studied. Sulfoethylated polyallylamine sorbents are distinguished by the highest silver(I) sorption selectivity and the shortest equilibration time. Sulfoethylated polyethyleneimines, unlike the other sorbents studied, can be used, depending on the pH of ammonium acetate buffer solution, for the group recovery of transition-metal ions or for co-recovering silver(I), copper(II), and nickel(II). The chemical structure of the polymer matrix and the degree of its modification do not significantly affect the initial silver(I) sorption rate from multicomponent solutions.

The process of Pd(II) sorption from hydrochloric acid solutions was studied in the pH range of 0.5–5.0 in the presence of Pt(IV) and a number of non-noble metal ions by poly( N -2-sulfoethylallylamine) (degrees of modification by sulfoethyl groups of 0.5 and 1.0) crosslinked with epichlorohydrin. It is shown that the degree of extraction of Pd(II) from multicomponent solutions containing transition metal ions Cu(II), Ni(II), Co(II), Zn(II), Cd(II), Mg(II), Pt( IV) is the largest. The selectivity coefficients of KPd(II)/Pt(IV) increase with an increase in the content of sulfoethyl groups in the aminopolymer and an increase in pH, which indicates that the Pd(II) sorption proceeds predominantly via the complex formation mechanism. It was found that the sorption equilibrium in the systems metal salt solution–sorbent is achieved within 240 and 120 min of phase contact for poly( N -2-sulfoethylallylamines) with modification degrees of 0.5 and 1.0, respectively. Under dynamic conditions, the studied sorbent, along with Pd(II), to a large extent extracts accompanying metal ions, which indicates a significant contribution of ion exchange to the mechanism of the sorption process.