The search for new sorbents for the concentration of substances is among the important tasks of analytical chemistry regarding the monitoring of water bodies in modern times. It is necessary to regularly control water supply sources, and the quality of natural water is also an indicator of the health of ecosystems. The use of sorbents when collecting water for analysis simplifies the preparation of complex samples, allowing to use a solid concentrate to determine the absorbate and quickly record the results using multi-element in situ instrumental methods. We suggested using cross-linked polyacrylates (CLPs) based on polyacrylamide as a new type of sorbent for these purposes. Unlike traditional sorbents, hydrogels noticeably swell in water (рН 4-7), which allows conducting the sorption of elements not only on the surface but also inside CLP granules. Sorption is conducted in a static mode by placing a weighed portion of CLP in a certain volume of water sample and by further drying in air at 70-100°C. The purpose of this work was to obtain and study solid polymer concentrates of CLP using EPR spectroscopy in order to confirm the sorption of elements in CLP for the further development of methods for the preparation of samples of various water bodies. To do this, we obtained individual and binary polymer complexes of paramagnetic elements Cu(II), Gd(III), V(IV), Mn(II), and Fe(III) from model solutions of their salts (from 10-7 (INAA) to 10-3 (EPR) mol/dm3) and dried them To confirm the sorption and reliable binding of elements into polymer complexes, we used ESR spectroscopy at 293 K. The experimentally obtained new EPR spectra were compared with the theoretical ones. Complex EPR spectra were simulated using original software developed at the Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences. It was shown that upon drying CLPs completely disengaged from water molecules, while the sorption of metals depended on the рН and grew with an increase in the solution’s рН. In case of joint presence, metal ions formed more complex compounds as compared to individual sorption. The hyperfine structure constant (HSC) was calculated for the spectra of complexes with CLPs and g-factor was calculated for all samples. It was determined that in the course of the formation of metal complexes with CLPs, the nearest coordination sphere was greatly distorted, while the nature of the distortion of the ligand environment depended on the element. In case of the Cu(II) and V(IV) system, we observed additivity of the EPR spectra, but in case of Cu and Gd(III) it was not recorded. In any case, the formation of strong and stable polymer complexes was confirmed. Sorption concentration using CLPs was proposed as a method of sample preparation of natural and technogenic water systems by transferring the determined ions into a solid hydrogel concentrate in order to be further analysed using multi-element instrumental methods (for example, X-ray fluorescence analysis (XRF), instrumental neutron activation analysis (INAA), etc.).

Using the synthesized salt Gd(NCS)3·6H2O, previously unknown mononuclear molecular complexes [Gd(H2O)(bpy)2(NCS)3]·0.5(bpy)·H2O, [Gd(H2O)(phen)2(NCS)3]·phen·0.5H2O as well as ionic ones [Hbpy][Gd(NCS)4(bpy)2]·H2O, [Hphen][Gd(NCS)4(phen)2] (bpy is 2,2'-bipyridine, phen is 1,10-phenanthroline) were prepared. Structural characteristics of the obtained compounds were determined using X-ray diffraction data. The magnetic susceptibility and EPR data of the new Gd complexes are considered taking into account the features of their composition and structure. Due to the peculiarities of the electronic structure, Gd complexes can serve as test systems for analyzing the field strength of ligands and the geometry of the local environment of the 4f-metal ion. It is shown that EPR spectroscopy is highly efficient method for determining the spin Hamiltonian parameters and, consequently, for characterizing the local environment of the gadolinium ion in complexes. However, the EPR method does not allow one to determine the sign of the splitting parameter in the zero field D, which requires additional studies.

Seven isostructural supramolecular adducts, [Ln2(O2CC6H3(NO2)2)6(DMSO)4]4(1,4-(H2N)2C6Me4) (Ln = Sm (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Y (7)), were synthesized by reacting LnCl36H2O with potassium 3,5-dinitrobenzoate in acetonitrile in the presence of 2,3,5,6-tetramethyl-1,4-phenylenediamine (DAD) and DMSO, and characterized by X-ray diffraction analysis. The charge transfer (CT) between DAD molecules and binuclear 3,5-dinitrobenzoate fragments gives rise to stacking interactions, which determine the supramolecular structures of complexes 1-7. Optical spectroscopy of complexes 1-7 corroborates the occurrence of significant CT, whereas magnetic studies substantiate the presence of a paramagnetic ion-radical structure which contributes to the magnetic moment of all the complexes and determines the paramagnetism of the yttrium compound 7. In the case of the latter complex, the value of the paramagnetic contribution resulting from CT was determined directly by magnetic measurement. It was demonstrated that this contribution decreases with the lowering of temperature, reflecting the depopulation of the triplet state of the CT complex, the ion-radical pair. A comprehensive EPR study of complex 7 was carried out by means of both continuous-wave (CW) and pulsed EPR spectroscopy in X- and Q-bands. The magnetic properties of complexes 2-6 indicate the prevalence of weak antiferromagnetic interactions within the binuclear fragments. The Dy complex exhibits field-induced single-molecule magnet (SMM) behaviour. The CT in the complex structures was modelled using DFT calculations.

In this work, binuclear, polymeric binuclear, and molecular 16-nuclear copper(II) complexes [Py2Cu2(Piv)4] (1), {[(EtOH)2Cu2(Chda)2]'EtOH}n (2) and [K2(H2O)6(Py)8Cu16(OH)2(Chda)16]'EtOH'MeCN'3H2O (3) (piv is pivalate, Chda is 1,1-cyclohexanediacetate) have been studied by EPR spectroscopy in the X-, Q-and W-bands. Polynuclear copper(II) complexes are formed by binuclear fragments bonded by bridging carboxylate anions. In compounds 1-3, only pairwise interactions between copper ions are observed, despite the fact that in 2 and 3 there may be additional interactions between copper ions belonging to different dimers.

Reactions of (Et3NH)2[B10Cl10] and organic ligands 2,2'-bipyridyl (Bipy) and 1,10-phenanthroline (Phen) in the acetonitrile–trifluoroacetic acid system have yielded compounds of composition (HL)2[B10Cl10]·3CH3CN (L = Bipy, Phen). The compounds have been characterized by IR spectroscopy, elemental analysis, and X-ray diffraction (CCDC nos. 2224377 and 2224378). It has been shown that in the presence of trifluoroacetic acid, protonation of organic ligands occurs with the formation of bipyridylium and phenanthrolinium salts, which are stabilized by the decachloro-closo-decaborate anion. It has been found that the cations participate in the formation of hydrogen bonds with the solvate molecules of acetonitrile, while only weak C–H…Cl and B–Cl…π interactions are observed for boron cluster anions.

The reaction between the 1,4-dioxane derivative of the closo-decaborate anion [2-B10H9O(CH2)4O]– with cyanide, hydrophthalate, and hydroiminoacetate ions has been studied. Alkali metal salts (K, Na, and Cs) of the closo-decaborate anion derivatives with pendant groups –NHCH2CH2NH2-, –OOC(o-C6H4)COOH-, –OOCCH2NHCH2COOH-, –OCH2CH2OH-, –CN-, –SCN-, and –SH- have been isolated. All compounds have been shown to have extremely low cytotoxicity (CT50 ~ 1000 μg/mL). It has been found that compounds Na2[B10H9O(CH2)2O(CH2)2SCN] and Na2[B10H9O(CH2)2O(CH2)2CN] exhibit activity and selectivity in vitro against the modern strain of SARS-CoV-2 coronavirus (IC50 312 and 625 μg/mL, respectively). In relation to influenza A virus and rabies virus, the compounds show weak antiviral activity at high concentrations (1250 μg/mL), i.e. show no selective effect on the reproduction of these viruses.

A new binuclear copper(II) complex Cu2(Piv)4(L)2, where Piv– = pivalate, L = 2,6-di-tert-butyl-4-(3,5-bis(4-pyridyl)pyridyl)phenol, was synthesized, and its molecular and crysral structures were determined at temperatures of 160, 173, and 296 K (CIF files CCDC no. 2144104, 2144105, and 2144106, respectively). Cyclic voltammetry measurements revealed three irreversible oxidation processes in the potential range of 0.5–1.2 V versus Fc+/Fc. Analysis of the temperature dependence of the magnetic susceptibility of Cu2(Piv)4(L)2 showed that antiferromagnetic interactions of Cu2+ ions predominate in the complex. It was found that the oxidation of Cu2(Piv)4(L)2 upon grinding with PbO2 or treatment of a solid sample with an aqueous solution of K3[Fe(CN)6] affords long-lived phenoxyl radical, which can be detected by ESR spectroscopy.

Introduction. Underground mining is carried out under conditions of intensive development of gas from combustion-engined vehicles and blasting operations, as well as under dust pollution and workplace temperature that violate health and safety regulations. Aerological safety provision by improving mine ventilation efficiency is therefore highly relevant. Methods of research. It is reasonable to ventilate a multi-horizon mine using an automated horizon ventilation system that is responsible for the compliance of aerological conditions in workplaces with the safety requirements and consists of centralized and decentralized blocks. Research results and analysis. The centralized block redistributes air flows between entries of a horizon. The decentralized block is a set of auxiliary fans represented by intelligent mechatronic modules supplying fresh air to the workplaces. The intellectualization of the auxiliary fan places high demands on the quality of the air duct, because the efficiency of ventilation in the workplace depends on its reliable functioning. Conclusions. Air duct made of hydraulically smooth polymer units sealed with each other allows to minimize auxiliary fan energy consumption under guaranteed supply of the required amount of air into the workplace. Horizon ventilation computer-aided control and auxiliary fans with sealed polymer air ducts will make it possible to create systems with the most advantageous combination of cost and quality

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Complexes [Сu2L4(MeOH)2] (I) and [СoL2] (II) are synthesized by the reactions of copper(II) and cobalt(II) acetates with 3-[5-p-tolyl)-1,3,4-oxadiazol-2-yl]acrylic acid (HL). The crystal structure of complex I is determined by X-ray diffraction (XRD) (CIF file CCDC no. 2052347). The crystals are monoclinic, space group C2/c, a = 26.056(4), b = 19.677(3), c = 13.998(2) Å, β = 91.571(3)°, V = 7175(2) Å3, ρcalc = 1.026 g/cm3, Z = 4. In a molecule of complex I, the pair of centrosymmetric copper atoms is bound by four bridging carboxyl groups. The intramolecular Cu…Cu distance is 2.654(2) Å. The coordination polyhedron CuO5 is a distorted square pyramid. The magnetic interactions between the copper(II) ions in complex I are shown to be antiferromagnetic (2J = –185 cm–1). In the case of complex II, the application of an external magnetic field decreases the magnetic relaxation rate. The Raman mechanism and direct mechanism are the most probable route for magnetization relaxation. Unlike the copper(II) complex, complex II is probably mononuclear in both the solution and solid phase.

Copper(I) and copper(II) complexation with N-donor heterocyclic ligands derived from benzimidazole has been studied. It has been found that starting from copper(II), dimeric [Cu-2(mu-SO4)(2)(DMF)(2)(H2O)(4)] and polymeric [Cu (mu-SO4)(DMF)(H2O)(2)](n) copper(II) complexes are isolated that contain no organic ligands. Under redox conditions, when starting from copper(I), the instability of the 1-(1-benzylbenzimidazol-2-yl)-N-cyclo-hexylmethanimine ligand is found, which leads to the formation of copper(II) complexes with the modified benzimidazole derivative [Cu(2-O(2)CBz-R)(2)] or [Cu-2(2-OCH(OH)Bz-R)(2)Cl-2] (Bz is benzimidazole, R = CH2-C6H5) depending on the solvent used. EPR spectroscopy revealed the presence of hyperfine interaction in compound [Cu(2-O(2)CBz-R)(2)].

Palladium(I) coordination polymers with unsaturated dicarboxylic acids, {[cis-Pd(C4H2O4)(H2O)]·(H2O)}n (I) (maleic acid), {[cis-Pd(C5H4O4)(H2O)]·2H2O}n (II) (citraconic acid), and {[trans-Pd(C4H2O4)(H2O)]·(H2O)}n (III) (fumaric acid) with stable paramagnetic centers in the polymer matrix were synthesized for the first time. According to IR and ESR spectroscopy data (determining the number of paramagnetic centers) and results of thermogravimetric analysis, the building blocks of I–III are, at least, tetranuclear Pd(I) clusters, in which palladium atoms are linked by bridging carboxylate groups. Each carboxylate group is coordinated via only one O atom, while the second O atom is linked to the nearest palladium atom of the neighboring cluster, thus giving a multidimensional coordination polymer. The coordination sphere of each Pd(I) atom in the cluster is completed by a water molecule and Pd–Pd bond. Heating of I–III results in the loss of solvation water molecules as the first stage. Above 100°C, the onset of removal of the coordinated water molecules is accompanied by complete decomposition of the complexes. On treatment of I with CH3CN in methanol, redox reaction takes place, in which complex I disproportionates to give Pd(II) complex and Pd(0) to give [Pd(HOOC–CH–CH(CH3O)(CH3CN)2] (IV) (CIF file CCDC no. 2039147).

Hydrogen adsorption ability is a key parameter characterizing advanced porous materials. Herein, the influence of platinum catalyst on the interaction of Cu-BTC with hydrogen is thoroughly investigated using volumetric measurements, calorimetric titration, XRD, and IR- and EPR spectroscopy. The first hydrogen adsorption by the Cu-BTC + Pt/C composite leads to an irreversible chemical reaction related to the formation of structural defects during synthesis. This process results in a partial reduction of Cu2+ to Cu0 and is accompanied by a decrease in the specific surface area and the appearance of additional mesopores. The following hydrogen adsorption-desorption cycles are completely reversible and reproducible. Besides, the Pt-containing material maintains a positive trend in excess adsorption up to ultra-high pressures in contrast with pristine Cu-BTC. Above 300-400 bars, it demonstrates a significant superiority in hydrogen capacity over the catalyst-free MOF. The possible nature of such a peculiar phenomenon is suggested.

A nontrivial case of a combination of ferro- and antiferromagnetic exchange interactions in mononuclear copper(ii) complexes, determined by HB networks, is reported.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.