In this study, we present the structures and properties of four novel nitrido-technetium complexes: [TcVNCl (Prd)4]TcO4 (I), [TcVNCl2(Pyr)2(OHMe)] (II), [TcVINCl2(Pyr)2OMe] (III), and [& micro;-NTcV2NCl4H2O(Bta)4] (IV) (Prd - pyridazine; Pyr - pyrazine; Bta - benzothiazole). The compounds were studied with ATR-IR and UV-Vis spectroscopies, TG-DTA, LIMS, pXRD, SCXRD, and DFT calculations. A comparison of structures and properties with previously described similar oxo-technetium complexes TcOCl2(Pyr)2OMe and TcOCl2(Pyrm)2OMe (Pyrm pyrimidine) is carried out. The formation of complexes II and III is influenced by the pH of the solution, the concentration of the N-donor ligand, and its structure. According to the findings of Hirshfeld and ESP surface analysis, complexes with a TcN core exhibit a greater degree of polarization in comparison to analogous compounds that feature a TcO core. The TcN complexes demonstrate higher reactivity under laser ionization and elevated temperatures in comparison to TcO complexes. Compound III undergoes decomposition at an elevated temperature of 115 degrees C, while the analogous complex with a TcO core has a higher decomposition temperature of 150 degrees C. Spectrophotometric studies of non-aqueous neutral solutions in the synthesis of TcN complexes of various structures have been carried out for the first time.

The radiation-chemical method for the synthesis of energetic metal-organic frameworks (eMOFs) based on zinc and cadmium tetrazolates was initially successfully applied. In both instances, the irradiation of doses of 100, 200, and 500 kGy resulted in the formation of a crystalline powder. The obtained compounds were characterized by XRD, FTIR, EDX and SEM in order to determine their structure and composition. The irradiation of solutions containing zinc and cadmium resulted in the formation of Zn5Tz9ClO4 & sdot;6H2O and Cd5Tz9ClO4 & sdot;6H2O in 100% DMF and pure water, respectively. The second phase, which has the structure ZnTz2 and CdTz2, is formed in the mixtures of DMF-water. It was determined that the solvent composition exerts a significant influence on the degree of crystallinity and the yield of the product. In the case of Zn-eMOF, the degree of crystallinity was observed to decrease with an increase of DMF: water ratio in the solvent. However, no such regularity was noted for Cd-eMOF. Only for 100% aqueous solution a crystalline phase was observed.

The goal of this work is to investigate the catalytic activities of low-coordination atoms located in gold nanoparticles. Gold nanoparticles with sizes from 0.7 to 40 nm deposited on γ-Al2O3 were used as a catalyst. Synthesized gold nanoparticles and prepared catalysts were characterized by HRTEM, SEM, XRD, DLS, and UV-Vis spectroscopy. The specific activity of gold nanoparticles towards the isotope exchange reaction at 77 K was studied as a function of nanoparticle size. The catalytic activity increases significantly when the particle size is less than 3 nm. The activities of low-coordination gold atoms located at the edges and in the corners are markedly different. Corner atoms (CN = 6) are more than 40 times more active in the reaction of hydrogen isotope exchange than edge atoms (CN = 7). TOF for atoms with coordination numbers CN = 6 and CN = 7 are 0.258 ± 0.020 and 0.006 ± 0.001 molecules site−1 s−1, respectively. An equation was proposed for the dependence of the catalytic activity of the reaction on the particle size, the number of atoms on the surface, and their activity.

The hydroconversion of asphaltenes into light hydrocarbons catalyzed by supported and free-standing non-noble metal nanoparticles was studied. The activity of Ni or Co immobilized on microspherical oxide carriers and Co nanoparticles dispersed in a hydrocarbon solution of asphaltene was found to be higher than that of a comparative Pt-Pd/Al2O3 catalyst. The yield of light products (C5+) reached up to 91% on cobalt nanoparticles supported onto alumina microspheres.

Herein, we report a method for the preparation of the first odd homometallic and heterovalent nine-centered Tc wheel, [Tc9(mu-O)9Cl6(OOCCl3)15]. The synthesized compound represents the pioneering instance of such clusters among d4 elements and is the fourth instance observed across all metals. The ring was synthesized by a solvothermal method in a solution of technetium acid in trichloroacetic anhydride. By single-crystal X-ray diffraction (XRD), powder XRD, and FTIR, the crystal structure was established. By UV-vis spectroscopy, thermogravimetric analysis, and density functional theory calculations, the optical, thermal, and some chemical properties were studied. The molar extinction coefficients in 16 solvents were determined. The heating of the complex in trichloroacetic anhydride leads to the formation of carbonyl compounds.

Herein, we studied the behavior of TcO4- in trifluoroacetic anhydride (TFAA) under visible light irradiation in situ by UV-vis spectroscopy. One carboxylate of Tc(VII) C2F3O5Tc (1) and two wheel-like carboxylate clusters of Tc(IV) Tc-8(mu-O)(8)(CF3COO)(16) (2, 3) and Tc-8(mu-O)(8)(C6H5COO)(16) (4) were synthesized and analyzed using pXRD, TGA, UV-vis spectroscopy, and SCXRD techniques. According to SCXRD, it was found that Tc(IV) trifluoroacetate exists in two crystalline modifications. By UV-vis spectroscopy and DFT calculations, it was shown that the primary compound in the reaction system is trifluoroacetate Tc(VII). A technetium trifluoroacetate(VII) and Tc intermediates of unidentified nature both show photosensitivity. The influence of intermolecular noncovalent interactions on the volatility of trifluoroacetate and benzoate Tc(IV) is shown. The main regularities of chemical transformations of technetium in nonaqueous solutions of carboxylates have been revealed. The obtained data on the kinetics of the process suggest that technetium in trifluoroacetic anhydride can simultaneously exist in the form of Tc(VII), Tc(VI), Tc(V), and Tc(IV). Under laser ionization or prolonged heating, the formation of the Tc(II,III)-cluster is observed

In this work, we propose a new method for determining the concentration of silver atoms in hydrosols of nanoparticles (NPs) stabilized with various capping agents. The proposed method is based on the determination of IBT absorption in the UV region (a broad band with a weakly pronounced shoulder at ~250 nm). To determine the extinction coefficient at 250 nm, we synthesized silver nanoparticles with average sizes of 5, 10, and 25 nm, respectively. The prepared nanoparticles were characterized by TEM, HRTEM, electron diffraction, XRD, DLS, and UV–Vis spectroscopy. It has been shown that the absorption characteristics of spherical NPs are not significantly influenced by the hydrosol preparation method and the type of stabilizer used. For particles with a size of 5–25 nm, the molar extinction coefficient of Ag0 atoms was found to be equal to 3500 ± 100 L mol−1 cm−1 at a wavelength of 250 nm. The results of the theoretical calculations of the molar extinction coefficients for spherical nanoparticles are in good agreement with the experimental values. ICP-MS analysis confirmed the applicability of this method in the concentration range of 5 × 10−7–1 × 10−4 mol L−1.

The great attention paid to silver nanoparticles is largely related to their antibacterial and antiviral effects and their possible use as efficient biocidal agents. Silver nanoparticles are being widely introduced into various areas of life, including industry, medicine, and agriculture. This leads to their spreading and entering the environment, which generates the potential risk of toxic effect on humans and other biological organisms. Proposed paper describes the preparation of silver hydrosols containing spherical metal nanoparticles by photochemical reduction of Ag+ ions with oxalate ions. In deaerated solutions, this gives ~10 nm particles, while in aerated solutions, ~20 nm particles with inclusion of the oxide Ag2O are obtained. Nanoparticles inhibit the bacterium Escherichia coli and suppress the cell growth at concentrations of ~1 × 10−6–1 × 10−4 mol L−1. Silver particles cause the loss of pili and deformation and destruction of cell membranes. A mechanism of antibacterial action was proposed, taking into account indirect suppressing action of Ag+ ions released upon the oxidative metal dissolution and direct (contact) action of nanoparticles on bacterial cells, resulting in a change in the shape and destruction of the bacteria.

The radiation stability of Portland cement and magnesium phosphate cement on gamma-irradiation was studied up the absorbed dose of 100 MGy. The radiation chemical decomposition of water contained in the cements was accompanied by hydrogen evolution. The evolution was retarded as the dose increased, with the limiting gas concentration,-2.6 L and-0.7 L kg(-1) of Portland cement and magnesium phosphate cement, respectively, being attained at-20 MGy. Oxygen was not released to free volume, but was entrapped by components of the materials. In the case of magnesium phosphate cement, the formation of MgO2 was established. A formal model for cement radiolysis was proposed, and an equation describing the hydrogen accumulation was derived. The formation of hydrogen did not induce swelling or destruction of the cements. The results can be used to assess the level of activity of radioactive waste that may be immobilized in these matrices.

The aim of the work was to synthesize new perspective compounds of palladium and platinum with nitrogenous bases (guanine), promising for use in biomedicine and catalysis. The article describes the synthesis of new [PdCl2(HGua)2]Cl2·H2O and [PtCl5(HGua)]·2H2O compounds using wet chemistry methods. The structure of the obtained single crystals was established by the method of single crystal X-ray diffraction. The complexes have an M-N bond, and the organic ligand is included in the first coordination sphere. The analysis of Hirshfeld surfaces for the obtained complexes and their analogues for the analysis of intermolecular interactions was carried out. In the palladium complex we obtained, π-halogen and π-stacking interactions were found; in analogues, such interactions were not found. π-halogen and halogen interactions were found in structure of platinum complex and its analogues.

Metal-organic frameworks (MOFs) demonstrate unique properties, which are prospective for drug delivery, catalysis, and gas separation, but their biomedical applications might be limited due to their obscure interactions with the environment and humans. It is important to understand their toxic effect on nature before their wide practical application. In this study, HKUST-1 nanoparticles (Cu-nanoMOF, Cu3(btc)2, btc = benzene-1,3,5-tricarboxylate) were synthesized by the microwave (MW)-assisted ionothermal method and characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) techniques. The embryotoxicity and acute toxicity of HKUST-1 towards embryos and adult zebrafish were investigated. To gain a better understanding of the effects of Cu-MOF particles towards Danio rerio (D. rerio) embryos were exposed to HKUST-1 nanoparticles (NPs) and Cu2+ ions (CuSO4). Cu2+ ions showed a higher toxic effect towards fish compared with Cu-MOF NPs for D. rerio. Both forms of fish were sensitive to the presence of HKUST-1 NPs. Estimated LC50 values were 2.132 mg/L and 1.500 mg/L for zebrafish embryos and adults, respectively. During 96 h of exposure, the release of copper ions in a stock solution and accumulation of copper after 96 h were measured in the internal organs of adult fishes. Uptake examination of the major internal organs did not show any concentration dependency. An increase in the number of copper ions in the test medium was found on the first day of exposure. Toxicity was largely restricted to copper release from HKUST-1 nanomaterials structure into solution.

Cementitious materials are widely applied as a matrix for the immobilization of low- and intermediate level radioactive waste. The use of these materials for high-level waste localization requires knowledge of their properties at high irradiation doses. We have studied the gas evolution and changes in the mechanical strength, composition, and structure of ordinary Portland cement (OPC) upon its irradiation up to absorbed doses of 100 MGy. The decomposition of water present in the cement is accompanied by hydrogen evolution. No oxygen formation was detected. The hydrogen accumulation is described by an exponential equation; the limiting gas concentration reached is approximately 2.8 L per 1 kg of cement. The mechanical strength up to absorbed doses of tens of megagrays varies insignificantly. Irradiation with accelerated (8 MeV) electrons exerts virtually the same effect as does 7-irradiation to the same absorbed dose. The structure, composition, and morphology of cement samples remain virtually unchanged up to high absorbed doses. (C) 2021 Elsevier Ltd. All rights reserved.

Two new gold(III) complexes with adenine or guanine nitrogenous bases as counter-cations were synthesized. These are 6-amino-7 H -purine-1,9-diium tetrachloridogold(III) chloride monohydrate, (C 5 H 7 N 5 )[AuCl 4 ]Cl·H 2 O, 1 , and 2-amino-6-oxo-6,7-dihydro-1 H -purin-9-ium tetrachloridogold(III) hemihydrate, (C 5 H 6 N 5 O)[AuCl 4 ]·0.5H 2 O, 2 . Their crystal structures were studied using single-crystal X-ray diffraction and FT–IR spectroscopic techniques. The arrangement of species in the studied crystal structures implies π-stacking interactions, as well as concomitant C—H...π interactions, hydrogen bonds and other types of noncovalent interactions, which were studied qualitatively and quantitatively using the method of molecular Voronoi–Dirichlet polyhedra. The variation of the nitrogenous base from adenine to guanine results in evident differences in the packing of the species in the crystals of 1 and 2 . The splitting and shifting of bands in the FT–IR spectra of the title compounds reveals several features representative of noncovalent interactions in their crystal structures.

Gold nanoparticles supported on gamma-Al2O3 catalyzed the hydrogen isotope exchange H-2 + D-2 at low temperatures, ca. 77 K. The specific catalytic activity increases by a factor of similar to 800 as the particle size decreases from 39.3 to 0.7 nm. A correlation has been established between the catalytic activity of nanoparticles of different size and the concentration of low-coordination gold surface atoms. Apparently, the obtained empirical equations can be used to estimate the specific catalytic activity of gold nanoparticles of various sizes.

Palladium nanoparticles catalyze the reduction of Ag+ ions with hydrogen on their surface, thereby leading to the formation of bimetallic particles with the “core–shell” structure. The catalytic reaction of methylviologen reduction with hydrogen at ratio [Ag] : [Pd] > 1 is suppressed by silver atoms located on the surface of palladium nanoparticles. At [Ag] : [Pd] ≤ 1, the reduction takes place; however, it is preceded by an induction period, and, the higher the silver content on the nanoparticle surface, the longer the induction period. The rate constant of the catalytic reduction, which begins after the end of the induction period, decreases with increasing silver content on the surface of palladium nanoparticles.

Nowadays, there is a demand in the production of nontoxic multifunctional magnetic materials possessing both high colloidal stability in water solutions and high magnetization. In this work, a series of water-dispersible natural humate-polyanion coated superparamagnetic magnetite nanoparticles has been synthesized via microwave-assisted synthesis without the use of inert atmosphere. An impact of a biocompatible humate-anion as a coating agent on the structural and physical properties of nanoparticles has been established. The injection of humate-polyanion at various synthesis stages leads to differences in the physical properties of the obtained nanomaterials. Depending on the synthesis protocol, nanoparticles are characterized by improved monodispersity, smaller crystallite and grain size (up to 8.2 nm), a shift in the point of zero charge (6.4 pH), enhanced colloidal stability in model solutions, and enhanced magnetization (80 emu g−1).

A method for the preparation of a pure colloidal solution of silver (silver hydrosol) containing only small metal nanoparticles and carbonate ions stabilizing them was developed. For this purpose, a solution containing silver and oxalic acid salts was exposed to UV radiation of a low-pressure pulsed xenon lamp. The irradiation initiated Ag + reduction with oxalate ions to give metal nanoparticles and carbonate ions. The latter ensure the electrostatic protection of nanoparticles via the formation of an electric double layer. Variation of the process conditions (silver and oxalate concentrations, UV irradiation conditions, the presence of air, and so on) allows the preparation of silver hydrosols with nanoparticle size ranging from 5 to 30 nm. The hydrosol is aggregatively stable for several months. Graphical abstract .

The effect of borohydride concentration on the synthesis of gold nanoparticles in solutions of chloroauric acid, cetyltrimethylammonium bromide, and ascorbic acid in the absence of seeds has been studied systematically. Variations in the concentration of NaBH4 allow one to obtain particles of different sizes and shapes. A method has been developed for the one-stage synthesis of large pentagonal gold rods (the average length and thickness are 550 ± 135 and 71.2 ± 11.6 nm, respectively) with a high yield using borohydride in an ultra-low (≤5 × 10–8 mol/L) concentration. The resulting particles have been characterized using optical spectroscopy, scanning and transmission electron microscopy (including high-resolution technique), and electron diffraction.