Метатезис катионов аммония в (NH4)4[Mo12O28(μ-L)8] (L = pz (пиразолат) и trz(1,2,4-триазолат)) на тетрабутиламмоний проведен при кипячении в водном растворе с Bu4NOH. Замещение катионов и сохранение анионного кластерного фрагмента подтверждено рядом физико-химических методов анализа, включая рентгеноструктурный анализ, 1H ЯМР-спектроскопию и масс-спектрометрию. Полученные соединения растворимы и стабильны в органических растворителях, что позволило изучить их окислительно-восстановительные свойства. Согласно данным циклической вольтамперометрии соединения проявляют обратимое окисление с E1/2 = 0.26 и 0.61 В для L = pz и trz соответственно. С помощью квантово-химических расчетов изучена электронная структура и показано, что основной вклад в граничные молекулярные орбитали соединений вносят d-орбитали молибдена.

The metathesis of ammonium cations in (NH4)4[Mo12O28(μ-L)8] (L = pz (pyrazolate) and trz (1,2,4-triazolate)) with tetrabutylammonium is performed under boiling in an aqueous solution with Bu4NOH. The substitution of cations and the preservation of the anionic cluster fragment are confirmed by a number of physicochemical methods such as XRD, 1H NMR, and mass spectrometry. The resulting compounds are soluble and stable in organic solvents, so their redox properties are studied. According to the cyclic voltammetry data, the compounds exhibit reversible oxidation with E1/2 = 0.26 V and 0.61 V for L = pz and trz respectively. The electronic structure is studied by quantum chemical calculations. It is shown that the frontier molecular orbitals of these compounds are mainly composed of molybdenum d-orbitals.

The [Re6Te8(imzH)6]2+ cationic cluster complex prepared by the interaction of [Re6Te8 (TeI2)6]I2·[Re6Te8(TeI2)4(TeI3)2]·I2 with imidazole (imzH) in a sealed glass ampoule at 200 °C for 48 h. The composition of the obtained compound is confirmed by 1H NMR spectroscopy and high-resolution mass spectrometry. The single crystals suitable for SC-XRD are prepared by slow diffusion of diethyl ether vapors into a solution of the complex in DMF. According to the SC-XRD data, the resulting complex has the composition [Re6Te8(imzH)6]I2·2/3DMF. The compound crystallizes in the monoclinic crystal system, P21/c space group, with the following unit cell parameters: a = 18.0379(4) Å, b = 17.9945(5) Å, c = 33.1318(7) Å, β = 115.1829(10)°, V = 9732.0(4) Å3, Z = 6. It is also shown that this compound exhibits solid-state luminescence with an emission maximum at 730 nm characteristic of octahedral rhenium cluster complexes.

Катионный кластерный комплекс [{Re6Te8}(imzH)6]2+ получен взаимодействием [{Re6Te8}(TeI2)6]I2·[{Re6Te8}(TeI2)4(TeI3)2]·I2 с имидазолом (imzH) в запаянной стеклянной ампуле при 200 °С в течение 48 часов. Состав полученного соединения был подтвержден с помощью 1Н ЯМР спектроскопии, а также масс-спектрометрии высокого разрешения. Путем медленной диффузии паров диэтилового эфира в раствор комплекса в ДМФА удалось получить монокристаллы пригодные для рентгеноструктурного анализа, согласно данным которого образуется [{Re6Te8}(imzH)6]I2·2/3DMF. Соединение кристаллизуется в моноклинной сингонии, пространственная группа Р21/c, с параметрами элементарной ячейки a = 18.0379(4), b = 17.9945(5), c = 33.1318(7) Å, β = 115.1829(10)⁰, V = 9732.0(4), Z = 6. Более того, было показано, что соединение проявляет характерную для октаэдрических кластерных комплексов рения люминесценцию в твердом теле, с максимумом эмиссии 730 нм.

A cluster complex of the composition [Re6Te8(TeI2)6]I2·[Re6Te8(TeI2)4(TeI3)2]·I2 is obtained by a reaction between [Re6Te8Te7] and I2 in a sealed quartz ampoule at 400 °C. More than three times increase in the volume of the ampoule in which the reaction is performed with maintaining the other conditions is shown to lead to the formation of the previously described cluster complex [Re6Te8(TeI2)6]I2. An increase in the synthesis temperature to 450 °C leads to the formation of X-ray amorphous products of the unknown composition. The [Re6Te8(TeI2)6]I2·[Re6Te8(TeI2)4(TeI3)2]·I2 compound obtained at 400 °C crystallizes in the triclinic crystal system, space group P1̅ , and unit cell parameters a = 11.0859(3) Å, b = 11.9021(4) Å, c = 21.1308(7) Å, α = 79.259(2)°, β = 85.533(2)°, γ = 66.220(2)°, V = 2506.55(14) Å3, Z = 1. The crystal structure consists of four layers of two types that alternate along the c parameter: 1) the layer formed by iodine anions and [Re6Te8(TeI2)6]2+ cluster cations and 2) the layer formed by neutral cluster complexes [Re6Te8(TeI2)4(TeI3)2] and crystallization I2 molecules. Weak interactions between the adjacent cluster complexes are observed in both layers along with I⋯I halogen bonds. The layers are linked with each other via I⋯I and Te⋯I interactions.

We have previously shown that 5-arylaminouracil derivatives can inhibit HIV-1, herpesviruses, mycobacteria, and other pathogens through various mechanisms. The purpose of this study was to evaluate the potential of 5-arylaminouracils and their derivatives against leukemia, neuroblastoma, and glial brain tumors. 5-Aminouracils with various substituents and their 5'-norcabocyclic and ribo derivatives were screened for cytotoxicity against two neuroblastoma cell lines (SH-SY5Y and IMR-32), K-562 lymphoblastic cells, HL-60 promyeoloblastic cells, and low-passage variants of well-differentiated glioblastoma multiforme (GBM5522 and GBM6138). Cytotoxicity assessment by the standard MTT test showed that most of the compounds lack significant toxicity towards the above cells. However, 5-(4-isopropylphenylamine)uracil and 5‑(4-tert-butylphenylamine)uracil exhibited a dose-dependent toxic effect towards the GBM6138 cell line with half-maximal inhibitory concentrations (IC50) of 9 and 2.3 μM, respectively. Antitumor activity was for the first time demonstrated for compounds of this type and can serve as a starting point for further research.

On the territory of Central Siberia, hundreds of forest fires occur annually, spreading over vast areas. An analysis of the dynamics of forest fires showed that in recent decades the number of fires and the burned area have increased significantly. The average area of one fire has also increased, which indicates the insufficient effectiveness of the organization of forest fire protection. The maximum number of fires occurs in the Nizhneangarskiy taiga region, where pine forests predominate, in which cutting have been actively carried out since the middle of the last century. The largest burned area was registered in the Central Siberian plateau taiga region, where forests are inaccessible and a zone control by only remote-sensing instruments has been allocated. The largest number of fires from thunderstorms was also recorded in this forest region (93.1 %). The main number of large and catastrophic fires operated in the control zone. The meteorological factors influencing the occurrence of forest fires are analyzed and regression models of the dependence of the number of forest fires on temperature and precipitation for different forest regions are obtained. The main causes of fires are the emergence of a large number of fires sources due to the intensive economic development of forest areas and increased thunderstorm activity due to climate change. The use of a regression model of the relationship between the number of forest fires and the average air temperature and the amount of precipitation for the fire season allows to qualitatively estimate the system of protecting forests from forest fires. At the same time, in some forest regions, there is a decrease in the effectiveness of protecting forests from fires, the increase in the number of which is due to climate change.

The correlation of histological features of papillary thyroid cancer with clinical and morphological prognostic factors and cause-specific mortality was analyzed in a case-control study within a cohort of patients from the Altai Regional Oncology Center (25 cases with lethal outcome and 64 follow-up controls). Significant variability was revealed in the histological structure of papillary thyroid cancer with the prevalence of classic (62%) and less frequent follicular (19%), tall cell (8%), and solid (7%) variants. In comparison with the classic variant, the solid variant was more often associated with male sex and large tumor size; follicular and tall cell variant was associated with more frequent metastases to regional lymph nodes; follicular and solid variants were associated with an increased proportion of cases with disease stages III-IV. The main differences reflecting the effect of histological factor on the disease outcome were associated with the solid variant of papillary thyroid cancer that was detected in 21% of lethal cases and only in 2% of control subjects. The detection of this variant can be of importance as an additional prognostic factor of the postoperative survival in papillary thyroid cancer.

The ligand environment of the [{Mo_5S_5^i(pz)_4^i}(pzH)_5^t]Br_2 cluster complex is modified by a reaction of the cluster with Br 2 in N,N-dimethylformamide at room temperature, which results in bromination of all pyrazole and pyrazolate ligands at the fourth position and in bromide ligand substitution for apical pyrazole. The solvent effect on ligand bromination is considered. The [{Mo_5S_5^i(4-Br-pz)_4^i}(4-Br-pzH)_4^bsBr^a]Br·Et_2O·5DMF cluster complex crystallizes in the tetragonal symmetry (space group P 4/ n ) and forms infinite layers via hydrogen bonds between the terminal 4-bromopyrazole ligands and the bromine anion. The complex also demonstrates reversible one-electron reductions of the cluster core shifted relative to the initial compound by 30 mV and 90 mV towards larger potentials.

Nanosized (d ∼70 nm) particles of metal-organic framework (MOF) based on zirconium and 2-aminoterephthalic acid, NH2-UiO-66, were prepared by a simple one-pot method. Due to the small particle size, the presence of amino groups, low toxicity, and high sorption capacity caused by large pore size, the obtained MOF is a perfect platform for the preparation of combined cytostatic agents with prolonged action. Nano-MOF is highly stable in distilled water, which allows for the sorption of a cytostatic drug without crystal destruction. The MOF gradually loses crystallinity in phosphate-buffered saline (pH 7.4), resulting in a gradual release of the drug under near-physiological conditions. Sorption studies have shown that approximately 50

Октаэдрические кластерные комплексы рения состава [{Re6(μ3-Q)8}(imz-[1,2-a]py)6]Br2, где Q = S, Se, получены при взаимодействии Csn[{Re6(μ3-Q8)}Br6] (n = 4 для Q = S; n = 3 для Q = Se) с избытком имидазо-[1,2-а]пиридина в запаянной стеклянной ампуле при 180 °С в течение двух суток. Оба соединения являются изоструктурными и кристаллизуются в тригональной пространственной группе R–3. Кристаллическая структура комплексов представляет собой три разнонаправленные цепочки из катионов [{Re6Q8}(imz-[1,2-a]py)6]2+ и анионов брома, которые связаны между собой водородными связями С—H⋯Br⋯H—C. Полученные соединения обладают ярко-выраженной люминесценцией с максимумами эмиссии на 652 нм и 678 нм для Q = S, Se соответственно.

Abstract—This study aimed to determine how to eliminate and/or increase the radiosensitivity of a population of cancer stem cells that are responsible for radioresistance in malignant neoplasms. The single and combined effects of γ-radiation at a dose of 4 Gy and dimeric bisbenzimidazoles of the DB(n) series on the cancer stem cells have been studied using the MCF-7 human breast cancer cell line. The DB(n) molecules contain n (five or seven) methylene groups in the linker between two benzimidazoles. It has been shown that DB(5) significantly reduces the relative and absolute numbers of the cancer stem cells by factors of 5.8 and 7.5, respectively, compared to the control (p = 0.001 in both cases), and DB(7) reduces the above cell numbers by factors of 3.6 (p = 0.003) and 5.2 (p = 0.004), respectively. Irradiation leads to an increase of the relative and absolute numbers of cancer stem cells by factors of 1.7 and 1.6 (p < 0.05) compared to the control, respectively. The combined effects of DB(5, 7) and ionizing radiation led to a significant decrease in the relative number of cancer stem cells by factors of 8.2 and 4.1, respectively, compared to only the single irradiation (p = 0.003 and p = 0.004). Even more pronounced outcomes of the combined action of DB(5, 7) and radiation have been found with regard to the absolute number of cancer stem cells, which decreases by factors of 16.6 and 14.1, respectively, compared to those after only single irradiation (p = 0.006 in both cases). The combined effect of DB(5, 7) and ionizing radiation led to the inhibition of the radiation-induced epithelial-mesenchymal transition as shown by the expression of vimentin, which is one of the markers of this process that plays an important role in the formation of cancer stem cells pool.

Octahedral rhenium cluster complexes of the composition [{Re6(μ3-Q)8}(imz-[1,2-a]py)6]Br2, where Q = S, Se, are obtained by the interaction of Csn[{Re6(μ3-Q8)}Br6] (n = 4 for Q = S; n = 3 for Q = Se) with an excess of imidazo-[1,2-а]pyridine in a sealed glass ampoule at 180 °С within two days. Both compounds are isostructural and crystallize in the trigonal space group $$R\bar{3}$$ . The crystal structure of the complexes represents three differently directed chains of [{Re6Q8}(imz-[1,2-a]py)6]2+ cations and bromine anions linked with each other by С–H⋯Br⋯H–C hydrogen bonds. The compounds obtained have pronounced luminescence with emission maxima at 652 nm and 678 nm for Q = S, Se respectively.

The fluorimetric method of analysis has been proposed for the qualitative and quantitative determination of the food flavoring additive quinine in the tonic water. The fluorimetric method of analysis has high sensitivity, selectivity and express speed compared to the other methods. The optimal conditions for the quinine fluorimetric determination in the soft drinks were found: solvent - 0.01 M sulfuric acid, excitation wavelength of 353 nm, luminescence wavelength of 452 nm, strobe parameters - signal delay of 0.85 μs, signal duration of 21.25 μs. To increase the sensitivity of the developed method, quinine luminescence was studied in the various concentrations of sulfuric acid from 0.005 to 1.000 M, and the quantum yield of quinine luminescence in all the investigated concentrations of sulfuric acid was calculated. It has been established that the highest quinine luminescence intensity, the highest quantum yield, and the lowest solvent background signal were observed in 0.01 M H 2 SO 4 . The influence of the related compounds of the food matrix on the fluorimetric determination of quinine was studied. It has been established that the content of such components as sugar and citric acid in the soft drinks does not affect the luminescent signal of quinine. The detection limit of quinine was calculated, which amounted to 0.0019 mg/dm 3 . In order to verify the correctness of the fluorimetric method, the results were compared with the spectrophotometric method (maximum absorption of quinine at 347 nm). The results obtained by the two methods were in good agreement, and the detection limit of the fluorimetric method was higher compared to the known works. The proposed technique could be used to control the quality and safety of the soft drinks. Keywords : quinine, fluorimetry, tonic water, luminescence quantum yield, strobe parameters. DOI: http://dx.doi.org/10.15826/analitika.2019.23.3.007 (Russian) A.А. Nikolaeva, A.A. Ivanov, E.I. Korotkova National Research Tomsk Polytechnic University, Lenina prosp., 30 Tomsk, 634050, Russian Federation

The fluorimetric method of analysis has been proposed for the qualitative and quantitative determination of the food flavoring additive quinine in the tonic water. The fluorimetric method of analysis has high sensitivity, selectivity and express speed compared to the other methods. The optimal conditions for the quinine fluorimetric determination in the soft drinks were found: solvent - 0.01 M sulfuric acid, excitation wavelength of 353 nm, luminescence wavelength of 452 nm, strobe parameters - signal delay of 0.85 μs, signal duration of 21.25 μs. To increase the sensitivity of the developed method, quinine luminescence was studied in the various concentrations of sulfuric acid from 0.005 to 1.000 M, and the quantum yield of quinine luminescence in all the investigated concentrations of sulfuric acid was calculated. It has been established that the highest quinine luminescence intensity, the highest quantum yield, and the lowest solvent background signal were observed in 0.01 M H 2 SO 4 . The influence of the related compounds of the food matrix on the fluorimetric determination of quinine was studied. It has been established that the content of such components as sugar and citric acid in the soft drinks does not affect the luminescent signal of quinine. The detection limit of quinine was calculated, which amounted to 0.0019 mg/dm 3 . In order to verify the correctness of the fluorimetric method, the results were compared with the spectrophotometric method (maximum absorption of quinine at 347 nm). The results obtained by the two methods were in good agreement, and the detection limit of the fluorimetric method was higher compared to the known works. The proposed technique could be used to control the quality and safety of the soft drinks. Keywords : quinine, fluorimetry, tonic water, luminescence quantum yield, strobe parameters. DOI: http://dx.doi.org/10.15826/analitika.2019.23.3.007 (Russian) A.А. Nikolaeva, A.A. Ivanov, E.I. Korotkova National Research Tomsk Polytechnic University, Lenina prosp., 30 Tomsk, 634050, Russian Federation