Методом монослоевого диспергирования было получено слоистое соединение дисульфида молибдена с катионными молекулами лекарственного средства ламивудин (Lam). Строение соединения установлено в результате моделирования порошковой дифрактограммы методом сверхъячейки и последующей квантово-химической оптимизации структурной модели методом функционала электронной плотности. С помощью топологического анализа расчетного распределения электронной плотности в рамках теории “Атомы в молекулах” (AIM) выявлены связывающие межатомные взаимодействия между Lam и монослоями MoS2 и оценены их энергии. Показано, что доминирующую роль в связывании играют водородные связи NH…S между Lam и сульфидным слоем, именно они определяют положение молекул в межслоевом пространстве MoS2. С использованием расчетной модели расслоенного соединения установлены особенности связывания Lam с поверхностью монослойных частиц MoS2.

A layered compound of molybdenum disulfide with cationic molecules of the medication lamivudine (Lam) is prepared by the monolayer dispersion method. The structure of this compound is determined by modeling the powder XRD pattern using the supercell method followed by a quantum chemical optimization of the obtained structural model using the electron density functional method. The AIM (Atoms in Molecules) topological analysis of the calculated electron density distribution reveals interatomic bonding interactions between Lam and MoS2 monolayers. The energies of these interactions are estimated. It is shown that the interaction is mainly due to the NH⋯S hydrogen bonds between Lam and the sulfide layer and that these bonds determine the position of molecules in the MoS2 interlayer The features of bonding between Lam and the surface of MoS2 monolayer particles are determined using a computational model of exfoliated compound.

Heterolayer MoS 2 compounds with molecules of protonated guanidine (GUA) and its aliphatic derivative 1,5,7- triazobicyclo[4.4.0]dec-5-ene (TABD) are prepared using single-layer dispersion of molybdenum disulfide. The structure of these compounds, including the geometry of sulfide layers and the localization of organic cations, is determined by powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and density functional theory (DFT) calculations. The analysis of the topology and energy characteristics of non-covalent bonding interactions within the Quantum Theory of Atoms in Molecules shows that the contribution of NH…S bonds to the stabilization of the heterolayer structure is essential in the compound with GUA and is significantly smaller than the contribution of CH…S contacts in the compound with TABD. Relation between the number and energetics of bonding contacts between the components with the geometry and positions of organic molecules in the interlayer space of MoS 2 is discussed.

С применением монослоевого диспергирования дисульфида молибдена получены гетерослоистые соединения MoS2 с протонированными молекулами гуанидина (GUA) и его алифатического производного, 1,5,7-триазобицикло[4.4.0]дец-5-ена (TABD). Строение соединений, включая геометрию сульфидных слоев и локализацию органических катионов, установлено на основе данных порошковой рентгеновской дифракции (PXRD), просвечивающей электронной микроскопии (TEM), термогравиметрического анализа (TGA), дифференциальной сканирующей калориметрии (DSC) и квантово-химических расчетов методом функционала плотности. Анализ топологии и энергетических характеристик нековалентных связывающих взаимодействий в рамках теории “Атомы в молекулах” (AIM) показал, что вклад NH…S связей в стабилизацию гетерослоистой структуры, который является определяющим для соединения c GUA, существенно уступает вкладу CH…S контактов в случае соединения c TABD. Обсуждается взаимосвязь набора и энергетики связывающих контактов между компонентами с геометрией органических молекул и их положением в межслоевом пространстве MoS2.

A layered compound with regularly alternating monolayers of MoS2 and N,N,N',N'-tetramethylguanidine (TMG) is synthesized by the reaction of monolayer dispersions of molybdenum disulfide containing anionic particles (MoS2)x– with protonated TMG molecules. It is found by a combination of methods (X‑ray diffraction analysis adapted for turbostrate-disordered systems, high-resolution transmission electron microscopy, FT-IR spectroscopy, and quantum-chemical calculations by the density functional theory) that the structure of MoS2 layers with octahedrally coordinated molybdenum atoms forming chains of Mo–Mo bonds is stabilized in the compound. Noncovalent binding interactions occur between the MoS2 monolayers and TMG molecules including CH…S, NH…S, and N…S contacts with the predominant contribution of contacts of the first type to the binding energy (СIF file CCDC no. 1 990439).

The atomic structure of the layered nanocrystalline molybdenum disulfide compound with trimethylphenylammonium cations has been determined for the first time using X-ray powder diffraction analysis adapted for turbostratically disordered systems and quantum chemical density functional theory calculations. It has been demonstrated that, in this compound, a conducting modification of MoS2 monolayers is stabilized, which is metastable under common conditions. Bonding interaction inside the molybdenum disulfide layers as well as between these layers and organic cations, revealed in the framework of Bader's atoms in molecules theory, has been considered.

The tribological behavior of two types of nanocrystalline molybdenum disulfide produced from natural molybdenum disulfide by monolayer dispersion in the presence of water (nano-MoS2(H2O)) and acetonitrile (nano-MoS2(CH3CN)) is studied. The study of the friction of these materials against polished and ground steels, as well as XPS examinations, show the advantage of the more thermally stable nano-MoS2(CH3CN), which is primarily due to the origin of low-molecular products adsorbed on the surfaces of nanoparticles.

The structural and photoelectric properties of nanodispersed molybdenum disulfide films intercalated with cationic organic compounds (rhodamine 6G, oxazine, triethylbenzylammonium, hexadecyltrimethylammonium, and polyvinylpyrrolidone) and hydroxocomplexes of Zn, Co, Ni, and Cd are studied. It is found that the greatest differences between the absorption spectra of MoS 2 films intercalated with compounds of various natures are observed in the range of 500–850 nm, and the conductivities (dark and photo-) of MoS 2 films intercalated with Ni or Co hydroxocomplexes rise by one or more orders of magnitude, respectively, compared to films of intercalated molybdenum disulfide. The correlation between photoconductivity and the corresponding values of dark conductivity is determined, proving that charge transport (and not generation processes) in films is the limiting step for photocurrent. It is concluded that highly conductive polycrystal films of intercalated MoS 2 with conductivities close to those in MoS 2 monocrystals are of interest for practical use in optoelectronics.

Here, we report the synthesis, characterization, and properties of novel nanohybrids formed by self-assembly of negatively charged MoS2 nanoplates and positively charged iron oxide nanoparticles (NPs) of two different sizes, 5.1 and 11.6 nm. Iron oxide NPs were functionalized with an amphiphilic random copolymer, quaternized poly(2-(dimethylamino)ethyl metacrylate-co-stearyl metacrylate), synthesized for the first time using atom transfer radical polymerization. The influence of the MoS2 fraction and the iron oxide NP size on the structure of the nanohybrids has been studied. Surprisingly, larger NPs retained a larger fraction of the copolymer, thus requiring more MoS2 nanoplates for charge compensation. The nanohybrid based on 11.6 nm NPs was studied in oxidation of sulfide ions. This reaction could be used for removing the dangerous pollutant from wastewater and in the production of hydrogen from water using solar energy. We demonstrated a higher catalytic activity of the NP/MoS2 nanohybrid than that of merely dispersed MoS2 in catalytic oxidation of sulfide ions and facile magnetic recovery of the catalyst after the reaction.

Intercalated group IVB-VIB metal disulfides and diselenides MX2 (M = Ti, Zr, Nb, Mo) can be obtained by electrochemical reduction of the corresponding MX2 in the presence of tetraalkylammonium salt. An original approach was used, which allowed effective reduction of these insoluble substances in the form of powders suspended in an organic solvent using the standard electrolysis technique in solutions in a one-space electrolyzer with a soluble anode. Using electron transfer mediators in the process afforded intercalated compounds with yields of 60–100%.

The product of exfoliation and restacking of MoS2 in acidic conditions is studied in detail using X-ray powder diffraction, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The temperature dependence of powder patterns reveals that the heating of exfoliated-restacked MoS2 is a way to a new nanostructured MoS2-based layered material that remains nanosized even upon heating to 850 degrees C. Previously this material has been described as 2H-MoS2, but according to the X-ray diffraction (XRD) data, its structure cannot be correctly described by any of the "usual" MoS2 polytypes. A model of the structure of the material describing its XRD patterns and thermal behavior is discussed in detail.

Исследованы структурные и фотоэлектрические свойства пленок нанодисперсного дисульфида молибдена, интеркалированного катионными органическими соединениями (родамин R6G, оксазин, триэтилбензиламмоний, гексадецилтриметиламмоний, поливинилпирролидон), гидроксокомплексами Zn, Co, Ni, а также кадмием. Обнаружено, что наиболее значительные различия в спектрах поглощения пленок MоS2, интеркалированного соединениями разной природы, наблюдаются в области 500–850 нм, а проводимости (темновая и фото-) пленок MoS2, интеркалированного гидроксосоединениями Ni или Со, увеличиваются соответственно почти на порядок или более по сравнению с пленками неинтеркалированного дисульфида молибдена. Установлена корреляция величин фотопроводимости с соответствующими значениями темновой проводимости, свидетельствующая о том, что транспорт зарядов (а не процессы генерации) в пленках является лимитирующим процессом для фототока. Сделан вывод, что высокопроводящие поликристаллические пленки интеркалированного MoS2 с проводимостями, близкими к проводимостям в монокристаллах MoS2, могут представлять интерес для практического использования в оптоэлектронике.

Preparing MoS2 films in mild conditions, using deposition of suspended MoS2 nanoplatelets onto the substrate is described. For this purpose, the nanosized MoS2 particles were obtained via restacking of MoS2 single layers produced by chemical exfoliation of bulk MoS2 crystals in liquid media. X-Ray diffraction study of the films showed that the basal planes of MoS2 crystallites are mainly oriented in the plane parallel to the substrate. Atomic force microscopy examination revealed the dependence of the film surface topography, as well as the roughness characteristics on the film thickness, which varied in the range of 0.03-2.2 mm. Optical absorption spectra of the obtained MoS2 films were found to contain the same absorption bands as the spectra of thin natural MoS2 single crystals. Dark conductivity of the films was determined to be ~ 10–3 S∙сm–1 at 300 K. The present MoS2 films were found to be photosensitive in the range of 300-800 nm, providing the maximum value of photocurrent under photoexcitation at ~ 440 nm.

Poly(meth)acrylates of three types, namely, regular homopolymers containing side-chain tetraalkylammonium ionic groups with alkyl radicals of various lengths (C6 and C16), a copolymer with statistically distributed ionic and long-chain (C18) alkyl groups, and a block copolymer of the same composition in which alkylammonium and alkyl groups are located in separate blocks, are synthesized with the use of controlled radical polymerization processes. The interaction of the polymers with molybdenum disulfide singlelayer dispersions yields self-organized organic-inorganic nanocomposites containing up to 40% polymer. As evidenced by powder X-ray diffraction and high-resolution transmission electron microscopy structural studies of the composites, they possess a crystalline layered structure with interlayer distances depending on the composition and structure of the polymer. Structures with the most regular alternation of organic and inorganic layers are formed in the case of homopolymers. The orientation of their alkylammonium fragments relative to MoS2 layers depends on the length of the alkyl radical and corresponds to their parallel (C6) or perpendicular (C16) arrangement.