Journal of Structural Chemistry最新文献

Heterogeneous catalysts xRu/Ce_0.75Zr_0.25O₂ (x = 1, 5 wt.%) are prepared by the sorption-hydrolytic precipitation. It is shown that these catalysts are active in the methanation of carbon dioxide. The composition and structural features of these compounds are studied by a complex of methods such as powder XRD, high-resolution electron microscopy, chemisorption, and X-ray photoelectron spectroscopy (XPS). It is established that catalysts obtained by the sorption-hydrolytic method contain the active component in a highly dispersed state. The catalyst with 1 wt.% Ru contains ruthenium compounds in the form of atomic clusters, while that with 5 wt.% Ru contains, along with ultrafine forms, also crystallized ruthenium-containing particles. It is shown that the initial catalysts contain oxide ruthenium compounds that are reduced to the metallic state under the methanation reaction conditions. In situ studies by powder XRD, XPS studies, temperature-programmed reduction in the hydrogen atmosphere (H2-TPR) show that metal ruthenium particles, which were obtained by the activation treatment of the catalysts as a result of heating in a hydrogen-enriched flow, promote the process of the partial reduction of the support material particles due to the spillover effect.

The crystal X-ray structure of 3-(pyrrolidine-1-carbonyl)-2H-chromen-2-one (1) has been presented. The compound crystallizes in the triclinic space group (Pbar{1}) with two molecules in the unit cell characterized by unit cell parameters a = 7.8547(5) Å, b = 9.0159(5) Å, c = 9.1516(5) Ǻ, α = 76.623(2)°, β = 89.546(3)° and γ = 67.626(2)°. The experimental bond lengths and bond angles have been compared with DFT computed results. The Hirshfeld surface analysis of the compound has been presented.

This article presents a study on the synthesis and character of a new organic-inorganic hybrid [4FBzTPP]₂[CuBr₄] (1) ([4FBzTPP]⁺ is 4-fluorobenzyltriphenylphosphinium) by XRD, SEM, FTIR and UV-Vis. The XRD analysis showed that the hybrid 1 belongs to the triclinic space group P2₁ with b = 8.8600(10) Å, c = 16.4867(17) Å, α = 16.639(2)°, β = 96.342(4)°, V = 2415.6(5) Å³, and Z = 2. The hybrid consists of two [4FBzTPP]⁺ cations and one [CuBr₄]^2– anion, and the [CuBr₄]^2– exhibits a twisted tetrahedral coordination geometry with the average bond length between Cu–Br is 2.393 Å. The 3D network structure of 1 is formed by electrostatic terms and other intermolecular interactions. The hybrid material undergoes a direct optical transition and has energy gap values of 1.66 eV and 2.18 eV, indicating its potential as a semiconductor material for optical research. The hybrid material undergoes a direct optical transition and has energy gap values of 1.66 eV and 2.18 eV, showing that the hybrid material is a potential semiconductor material for optical research. In addition, the compound exhibited good antibacterial activity against E. coli and S. aureus.

The crystal structure of 2,3,5,6-tetraiodo-1,4-benzenedicarboxylic acid dihydrate is described and the following structural features are established by XRD: C₈H₆I₄O₆, M 705.73; monoclinic crystal system, P2₁/n space group; unit cell parameters: a = 5.78160(10) Å, b = 15.0976(2) Å, c = 17.3437(3) Å; α = 90°, β = 94.602(2)°, γ = 90°; V = 1509.02(4) Å³, Z = 4, ρ_calc = 3.106 g/cm³. Some features of the thermolysis of terephthalic acid and its iodine derivatives are described. Diiodoterephthalic acid is the least thermally stable, tetraiodoterephthalic acid is the most stable. The iodinated terephthalic acids have similar heats of fusion. The largest amount of carbon residue is formed during the decomposition of 2,3,5,6-tetraiodo-1,4-benzenedicarboxylic acid.

Neutral complex [L₂CoCl₂] is obtained by the reaction of cobalt(II) chloride with E-(((4-iodophenyl)imino)methyl)phenol (L), and its structure is studied by single crystal X-ray diffraction. The structure contains I⋯Cl halogen bonds whose energies are estimated by quantum chemical calculations.

We report a three-stage scheme (1) Pbt–NH₂ + CS₂ → (Pbt–NH)₂C=S (1) (Pbt = 4-(1′,3′-benzothiazole-2′-yl)phenyl), (2) 1 + PPh₃ + I₂ → Pbt–N=C=N–Pbt (2), (3) 2 + Ph₂PH → (Pbt–N)(Pbt–NH)CPPh₂ (3) for the synthesis of a novel luminescent phosphoguanidine 3 with an unprecedentedly high yield (90%) at the last catalyst-free stage. It is demonstrated by the density functional theory (DFT) method that high reactivity of 2, leading to such an yield, is explained by a high electrostatic potential at the central carbon atom. For 3, two polymorphs 3α, 3β and a solvatomorph 3γ·THF are prepared. The structures of 2, 3α, 3β, and 3γ·THF are determined by single-crystal XRD. The tendency of crystals of different phenylbenzothiazole derivatives to form different conformations is explained by the computational (DFT) data indicating that the energy change of the molecule of 3 considered as a function of the torsion angle between phenyl and benzothiazole fragments does not exceed 2 kJ/mol in the –15…30° range. Photophysical properties of 3β and 3γ·THF phases are studied. It is shown that these compounds exhibit photoluminescence with an emission maximum at 510 nm.

In the present study, we report the room temperature synthesis of a novel two-dimensional (2D) coordination polymer (CP) having the formula {[Cd(H-PCA)₂(H₂O)]·0.5(H₂O)·0.5(CH₃OH)}_n (CP1), where H-PCA represents 4-pyrazolecarboxylate. The synthesis of CP1 was achieved through a one-pot reaction, involving the self-assembly of Cd(OAc)₂·2H₂O and the multitopic mixed N- and O-donor ligand, 4-pyrazolecarboxylic acid (H₂-PCA), in methanol. This method demonstrated high yield and purity, enabling the facile production of multigram quantities of CP1 within a short timeframe. Notably, the synthetic procedure selectively deprotonates the carboxylic acid group while retaining the pyrazole moiety in its protonated form. CP1 has been thoroughly characterized using various analytical techniques, including single-crystal X-ray diffraction, FTIR spectroscopy, elemental analysis, scanning electron microscopy, thermogravimetric analysis, and powder X-ray diffraction. The structural analysis revealed that CP1 features a 3, 5-connected binodal net with the point symbol {4.5.6}{4.5⁵.6³.7}, leading to a unique -ths net topology. Through hydrogen bonding connections between adjacent 2D sheets, CP1 further extends into a three-dimensional (3D) supramolecular network due to the presence of coordinated water molecules and the protonated pyrazole group. Additionally, a 3D Hirshfeld Surface analysis accompanied by quantitative 2D fingerprint plots was also investigated to explore the intermolecular interactions.

Composition, structure, energy parameters, and existence regions of hydrate complexes formed in the HClO₄–H₂O system are studied by IR spectroscopy and quantum chemical methods. Three concentration-structural regions are determined. The HClO₄–H₂O solutions diluted to the 1:13.3 molar ratio of components contain (text{ClO}^{-}_4) and (text{H}_5text{O}^{+}_2) solvate-separated ions, each hydrated by four water molecules. More concentrated solutions (1:13.3-1:5) contain hydrated ion pairs (text{ClO}^{-}_4cdottext{H}_5text{O}^{+}_2) that are contact ion pairs if the [HClO₄]:[H₂O] ratio falls within the region 1:9-1:5. As the acid concentration increases further up to the transition of the HClO₄–H₂O system into the solid phase, pair complexes are formed. The structure of the latter is formed by a cycle of two contact ion pairs (text{ClO}^{-}_4cdottext{H}_5text{O}^{+}_2) connected by two H-bonds. The solid phase consists of interacting polymer chains formed by (text{ClO}^{-}_4cdottext{H}_5text{O}^{+}_2) and (text{ClO}^{-}_4cdottext{H}_3text{O}^{+}) ion pairs.

Two mineral species of the labuntsovite group from Khibiny (sample 1) and Lovozero (sample 2) alkaline massifs are analyzed by single crystal X-ray diffraction and Raman spectroscopy. They are intermediate members of the tsepinite-Na–“tsepinite-Ba”–tsepinite-K solid solution, which are characterized by a high degree of hydration and a low concentration of extra-frame cations. Parameters of monoclinic cells are: a = 14.5086(6) Å, b = 14.2174(6) Å, c = 7.8712(3) Å, β = 117.119(4)°, V = 1444.09(11) Å³ (sample 1) and a = 14.2582(4) Å, b = 13.7541(6) Å, c = 7.7770(2) Å, β = 116.893(4)°, V = 1360.20(9) Å³ (sample 2). Crystal chemical formulas (Z = 2) are: |^A[Na_0.84K_0.6[(H₂O)₄]_5.2]^BK_0.2^CBa_0.25^D[Ca_0.35Na_0.15Fe_0.025(H₂O)]| {M1(Ti_1.2Nb_0.8)M2(Ti_1.1Nb_0.9)(O,OH)₄(Si₄O₁₂)₂} for sample 1 and |^A[Na_1.6(H₂O,H₃O)_0.4]^BK₂^C(Ba_0.51Sr_0.21)^{D [Mn}_0.3Ca_0.2(H₂O)](H₂O)₄|{M1(Ti_1.94Nb_0.06)M2(Ti_1.88Nb_0.12)(O,OH)₄(Si₄O₁₂)₂} for sample 2. The high degree of hydration of sample 1 is expressed in the presence of proton hydrate complexes and tetrahedral [H₂O]₄-associates. Labuntsovite group minerals (LGMs) are characterized by so-called block isomorphism due to different distributions of D cations. Our analysis of heteropolyhedral MT-frameworks in LGMs allows us to determine the topological features of cation networks.

Four-component oxide catalysts MnO_x–CuO–ZrO₂–CeO₂ are synthesized by co-precipitation with varying the calcination temperature from 400 °C to 800 °C. Formation and decomposition processes in mixed oxides are studied by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The redox properties of the obtained samples are tested by temperature-programmed hydrogen reduction, and the catalytic characteristics are examined in the CO oxidation reaction. At 400-600 °C homogeneous solid solution Mn_xCu_yZr_zCe_qO₂ with the fluorite structure is formed. Temperature elevation to 700-800 °C facilitates the gradual decomposition of initial oxide, with manganese and copper cations leaving its composition in the form of highly dispersed CuO and Cu_xMn_3–xO₄ particles. The occurrence of different active states in the catalyst and their transitions into each other under the temperature effect is shown to maintain the high activity in the CO oxidation reaction up to 800 °C.