Crystal structure of 3-(1,3-benzoxazol-2-yl)-2-hydroxy-5-chlorobenzaldehyde is studied by XRD. The structure is shown to be planar due to the π-conjugation between aromatic cyclic fragments of the molecule and due to the formation of intramolecular O–H⋯N hydrogen bonding between the hydroxyl group and the nitrogen atom of the benzoxazole ring. The planarity of 3-(1,3-benzoxazol-2-yl)-2-hydroxy-5-chlorobenzaldehyde molecules enhances the formation of π–π stacking interactions between almost parallel molecules in the crystal packing.
A series of heterometallic tetrahedral cluster complexes with the general formula [Re4–xMxS4(CN)12]n– (M = Mo, W; x = 2, 3) is prepared by the interaction of ReI3 with molybdenum(VI) or tungsten(VI) trioxides MO3, elemental sulfur, and KCN at moderately high temperatures. The composition and structure of all the complexes is studied by single-crystal XRD and high-resolution mass spectrometry. It is shown that varying the stoichiometry of the reaction mixture in reaction with MoO3 yields [ReMo3S4(CN)12]7– and [Re2Mo2S4(CN)12]6– cluster anions as individual compounds, whereas compounds based on [ReW3S4(CN)12]7– and [Re2W2S4(CN)12]6– anions are formed simultaneously independently of initial ReI3/WO3 ratios. Nevertheless, these compounds are of great interest as rare examples of heterometallic rhenium and tungsten clusters.
A simple and convenient method is developed to synthesize a novel energetic structure: 3-iodo-1,3-dinitroazetidine (IDNAZ). The target compound is obtained in a 68
Polycrystalline diamond films are promising materials for the fabrication of X-ray detectors. This work concerns the effect of heating a polycrystalline diamond film in an ammonia atmosphere at 600 °C on the surface chemical state and photoconductivity under irradiation with bremsstrahlung from a copper anode X-ray tube. The diamond film is synthesized by chemical vapor deposition from a hydrogen-pentane mixture activated by microwave plasma discharge. Conductive electrodes having the comb-shaped meander geometry are formed on the film surface by ultraviolet laser irradiation at a wavelength of 355 nm. The chemical state of the material surface is investigated by X-ray photoelectron and Raman spectroscopic techniques. Heating in ammonia is found to alter the compositions and structures of both the initial diamond film surface and the laser–treated regions. Amino groups are attached to the diamond film surface (with a nitrogen concentration of about 1 at.
Structural features of aluminum nitride thin films, which are important for applications as a piezoelectric material, are studied. The films are grown by pulsed magnetron sputtering at deposition temperatures from 60 °C to 300 °C and a magnetron power of 300 W. The powder XRD analysis indicates textured growth of films along the c axis and a microstrain decrease with increasing deposition temperatures. The growth rate also decreases and the refractive index increases with increasing deposition temperature. The obtained patterns are explained by the ordering of the microstructure of the films with increasing deposition temperature due to increased mobility of atoms adsorbed on the substrate. It is shown by transmission electron microscopy and electron diffraction that the sample prepared at 200 °C is characterized by a lower disorientation of crystallites relative to the c axis than the samples deposited at 100 °C and 300 °C. For the sample prepared at 200 °C, the highest piezoresponse is qualitatively detected by piezoresponse force microscopy. The films exhibit two photoluminescence bands, the position and intensity of which do not depend on the growth temperature. The nature of defects corresponding to these bands is discussed.
Interaction of 4,7-dibromo-2,1,3-benzothiadiazole with methyl p-aminobenzoate under Buchwald–Hartwig amination conditions yields new derivatives: 4,7-di((4-methoxycarbonylphenyl)amino)-2,1,3-benzothiadiazole (1) and 4-bromo-7-((4-methoxycarbonylphenyl)amino)-2,1,3-benzothiadiazole (2). The structures of the compounds is determined by single-crystal XRD, NMR, and elemental analysis. The photophysical properties of the obtained compounds are studied both in solution and in the solid state. The luminescence of 1 is selectively quenched in the presence of Cu(II) cations, thereby highlighting prospects of using this compound as a fluorescent sensor.
The 3d–4f heterometallic complex [Dy((η4-sba)Fe(CO)3)2(DppfO2)2]Cl·8EtOH·H2O (Hsba is sorbic acid CH3(CH=CH)2CO2H; DppfO2 is Fe(η5-C5H4P(O)Ph2)2) is obtained by the interaction of DyCl3·6H2O, sorbic acid iron, tricarbonyland 1,1′-bis-(diphenylphosphinoxido)ferrocene in the presence of triethylamine in the organic medium and is structurally characterized. Its structure is composed of complex cations in which the Dy3+ ion is chelated by four organoiron ligands of two types [(η4-sba)Fe(CO)3]– and DppfO2, with two chiral carboxylatex ligands being present in each cation as one enantiomer. The structure also contains centrosymmetric associates Cl·H2O·8EtOH2 formed by hydrogen bonds. Themolysis of the complex is analyzed by thermal gravimetry and differential scanning calorimetry and is found to yield a mixture of FePO4, DyPO4, and Dy2O3.
A cyclic triradical metal complex is constructed from bridging 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) radical anions and indium cations. Molecular and crystal structures of the synthesized compound are determined by the single crystal X-ray diffraction analysis. According to the magnetochemical studies, strong antiferromagnetic coupling between unpaired electrons of tetrazine radical anions stabilizes the ground doublet spin state in the trinuclear indium complex obtained, with the quadruplet state being thermally available.
The air stability of mixed oxide Mn1.5Ga1.5O4 with the spinel structure is studied by in situ X-ray diffraction (XRD), thermogravimetric analysis, and transmission electron microscopy. The Mn1.5Ga1.5O4 behavior is shown to depend on the thermal treatment mode, and correspondingly, kinetics of the process. During continuous heating to 650 °C initial oxide decomposes into two cubic spinels: Mn1.5Ga1.5O4 and (Mn,[·])1.5(Ga,[·])1.5O4. They differ in the oxygen concentration. The amount of attached oxygen increases during stepwise heating, which increases the number of cationic vacancies in the (Mn,[·])1.5(Ga,[·])1.5O4 phase and generates additional superstructural XRD peaks. The difference in transformations is due to oxygen attachment kinetics, and consequently, the formation of cationic vacancies. Thus, upon rapid heating the vacancies are randomly arranged in the mixed oxide bulk, whereas upon longer heating their agglomeration and ordering are observed. Hydrogen reduction treatment results in the inverse process: oxygen evolution and recrystallization of the initial spinel.
A comparative quantum chemical study of the thermodynamic stability, electronic structure, and vibrational spectra of chromium(VI), molybdenum(VI), and tungsten(VI) halides and oxohalides are presented. The calculations are performed by the density functional theory methods using PBE, B3LYP, and r2SCAN density functionals in combination with def2-SVP, def2-TZVP, and def2-QZVP basis sets. The influence of the functional choice and the basis set size on the accuracy of describing geometric parameters and vibrational frequencies is analyzed against experimental data. The thermodynamic stability of the studied compounds is shown to decrease in the F → Cl → Br → I series, as well as with increasing coordination number of the central metal atom. At the same time, the polarizability and dipole moments of molecules increase, especially for structures with reduced symmetry. Analysis of frontier molecular orbitals (HOMO–LUMO) allows the identification of more reactive compounds that can be possibly used as precursors for atomic layer deposition and for identifying thermally stable products in atomic layer etching processes.
A new complex, [Zn2Cl4L]·MeCN, is prepared using an optically active ligand L containing two dipinodiazafluorene fragments connected by a =N–Ph–N= diimine linker. In the binuclear complex [Zn2Cl4L], ligand L binds two ZnCl2 units where Zn atoms occur in a distorted tetrahedral N2Cl2 environment (seesaw configuration). The geometry, electronic structure, and optical properties of the complex are studied by the density functional theory method. Experimental absorption and diffuse reflectance spectra of [Zn2Cl4L]·MeCN reveal electronic transitions in the 230-600 nm range and agree with the results of quantum chemical calculations.
Supramolecular complexes of the zwitterionic form of the glycyl-L-phenylalanine dipeptide with nucleosides (uridine, cytidine, adenosine, and guanosine) are investigated by quantum chemical simulations. Geometry optimization is performed using density functional theory; energy characteristics and electron density topology are analyzed using the quantum theory of atoms in molecules. It is shown that the complexes are stabilized by multiple intermolecular hydrogen bonds involving the protonated amino group NH_3^+ , the carboxylate fragment COO–, and the functional groups of nucleosides. Topological analysis of the electron density confirms the presence of medium-strength hydrogen bonds and numerous weak non-covalent interactions forming a cooperative network of intermolecular contacts. The stability of the complexes in a polarizable medium modeling the properties of water is shown to decrease in the series cytidine > guanosine > adenosine > uridine.
Silver(I) β-diketonates and their mixed-ligand complexes are used to prepare film materials and nanoparticles via solution- and gas-phase methods. To expand the library of precursors, in the present work, the corresponding derivatives with an extended perfluoroalkyl chain in the ligand, namely, Ag(I) complexes with 3H,3H-perfluorooctane-2,4-dione (Hdfod) is synthesized for the first time. Adducts with water/ether and acetonitrile are obtained along with a mixed-ligand complex with 2,2′-bipyridine [Ag(bipy)(dfod)]₂, for which a simplified synthetic procedure is proposed. All compounds are characterized by NMR spectroscopy. The structure and vibrational spectrum of the mixed-ligand complex are investigated using quantum chemical calculations. The single crystal X-ray diffraction analysis shows that in the structure of this binuclear complex, both types of ligands exhibit chelate coordination (d(Ag–O) = 2.38 Å, 2.31 Å; d(Ag–N) = 2.35 Å, 2.37 Å), and dimerization occurs through Ag⋯Ag (2.95 Å) and Ag⋯N (2.93 Å) contacts, similar to hexafluoroacetylacetonate analogue [Ag(bipy)(hfac)]2. The structure exhibits incommensurate static modulation, manifested as an Ag atom displacement from its average position and elastic breathing of the coordination core. In this process, the conformationally rigid bipy ligand moves as a whole, whereas the β-diketonate moiety undergoes synchronous deformation. The thermal properties of all compounds are studied by TGA, and the mixed-ligand complex is additionally investigated by DSC. The new complexes with L = dfod have lower melting points than their analogues with L = hfac, while the bipy mixed-ligand complex shows enhanced thermal stability.
In this study, the structure of (E)-2-bromo-4-methyl-6-[(4-bromophenylimino)methyl]phenol is investigated using X-ray diffraction (XRD), and its geometrical features are analyzed in detail. The title compound crystallizes in a monoclinic system with the space group P21/n. In salicylaldehyde derivatives, the presence of a strong tautomeric N–H⋯O or O–H⋯N hydrogen bond typically facilitates a nearly parallel orientation between the benzene rings. The angle between the normals of the benzene rings is determined to be 2.84°, confirming the near-parallel geometry. Nonlinear optical (NLO) analysis revealed that the structure exhibits well-defined charge separation with a total dipole moment (μtot) of 5.54 D. Additionally, graph set analysis and Hirshfeld surface analysis are employed to elucidate the intermolecular and intramolecular interactions to illustrate crystal growth symmetries. Moreover, the investigation of the title molecule′s reactive sites, possible charge mobility, and hardness is carried out using frontier molecular orbital (FMO) and MEP analyses. This investigation is completed with docking analysis of the possible binding features of the molecule specifically against 5U09 receptor.
The kinetics of water diffusion in metal-organic frameworks is critical for applications such as atmospheric water harvesting, yet its real‑time molecular‑level monitoring remains challenging. Herein, we propose an in situ electron paramagnetic resonance approach based on an encapsulated spin probe to investigate water diffusion into MOF UiO‑66. The EPR spectral lineshape is highly sensitive to the local mobility of the radical. As water molecules get adsorbed within the pores over the course of the measurement, the spectral lines gradually narrow. EPR measurements reveal that water uptake in TEMPO@UiO-66 is a slow process, taking place over more than 50 h. Molecular dynamics simulations corroborate these experimental findings, showing changes in radical motion with distinct trends during water adsorption. This approach enables real‑time monitoring of water diffusion, offering a versatile tool for studying host–guest dynamics in porous materials and guiding the development of advanced sorbents.
A new copper(II) carboxylate–bipyridine complex, bis(4-methylbenzoato-κ2O,O′)(4,4′-dimethyl-2,2′-bipyridine-κ2N,N′)copper(II), [Cu(4-mba)2(dmbpy)] (4-mba = 4-methylbenzoate; dmbpy = 4,4′-dimethyl-2,2′-bipyridine), is synthesized and structurally characterized by single crystal X-ray diffraction, which revealed a distorted octahedral coordination geometry. Intermolecular interactions are investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots, which demonstrated the contributions of hydrogen bonding, C–H⋯π, and π⋯π stacking interactions to the crystal packing. Density functional theory calculations at the B3LYP/LANL2DZ level are performed to optimize the molecular structure. Frontier molecular orbital, molecular electrostatic potential, and reduced density gradient analyses are used to examine the electronic properties, charge distribution and non-covalent interactions of the complex.
The plastic bending behavior of isostructural hexachlorobenzene and hexabromobenzene crystals is governed by anisotropic intermolecular interactions, particularly halogen–halogen (Hal⋯Hal) contacts. This study critically evaluates the reliability of Quantum Theory of Atoms in Molecules (QTAIM) and Non-Covalent Interaction index analyses in capturing the energetic landscape of layer sliding along the bending (001) crystallographic plane. Energy profiles are calculated using periodic Density Functional Theory, gas-phase DFT, and the CrystalExplorer cluster-based approach. While all computational methods confirm the presence of a significant energy barrier to sliding, analysis of the interaction energy contributions computed with CrystalExplorer17 reveals that changes in the dispersion component are minimal (<2
First example of structurally characterized mononuclear homoleptic aryloxide of hafnium(IV) is reported using alkane elimination route. The herein isolated hafnium(IV) tatrakis(2,6-diisopropylphenoxide), a rare example of homoleptic group 4 aryloxides is synthesized via toluene elimination reaction by reacting four equivalents of 2,6-diisopropylphenol with tetrabenzylhafnium precursor. The compound [C48H68HfO4], crystallized in the monoclinic space group, C2/c with unit cell parameters: a = 25.3120(6) Å, b = 10.8760(4) Å, c = 20.1250(5) Å, β = 125.939(3)°, V = 4485.6(2)) A3, Z = 4. The hafnium atom adopts a tetrahedral environment composed of oxygen atoms of the aryloxide ligands with crystal packing showing C⋯H π-interactions.
A pair of new copper(II) complexes [CuL(NO3)]·CH3OH·H2O (1) and [CuL(HL)]NO3·3CH3OH (2), where HL is the aroylhydrazone compound N’-(2-hydroxy-4-methoxybenzylidene)-4-methylbenzohydrazide, and L is its deprotonated form, are prepared by reaction of HL with copper nitrate in 1:1 and 2:1 molar ratio, respectively in methanol. The complexes are characterized by elemental analysis, infrared and electronic spectra, as well as single crystal X-ray determination. Urease inhibitory assay reveals that both complexes have effective activity, with IC50 (half maximal inhibitory concentration) values of 0.17 ± 0.22 μmol/L (1) and 17.2 ± 1.5 μmol/L (2).
This study explores the structural and electronic properties of two novel pyridinium-fused 1,2,4-diselenazolium salts containing aryl substituents and either perchlorate or perrhenate anions. Single crystal X-ray diffraction analysis reveals that the bicyclic heterocycles exhibit non-planar geometries, with the two selenium atoms displaying distinct coordination environments: a T-shaped geometry for Se1 and a bent geometry for Se2. In the solid state, these compounds form supramolecular dimers driven by multicenter Se⋯O chalcogen bonding interactions between the cationic core and the oxoanions. Theoretical investigations using Density Functional Theory and Quantum Theory of Atoms in Molecules topological analysis confirm the nature of these noncovalent contacts. The estimated interaction energies for the Se⋯O contacts range from 0.9 kcal/mol to 4.1 kcal/mol, characterizing them as purely noncovalent, attractive bonding interactions. These findings provide additional insights into the directional chalcogen bonding capabilities of diselenium-containing heterocycles, expanding their potential utility in anion recognition and crystal engineering.
