Journal of Structural Chemistry最新文献

Single crystals of chiral coordination polymer [Zn(R-Hhhm)₂] (1) are obtained in the interaction of zinc acetate and R-hexahydromandelic acid (R-H₂hhm) in a water-methanol solution. The compound has a chain structure, which is determined by single crystal X-ray diffraction with synchrotron radiation. Coordination polymer [Zn(R-Hhhm)₂] is the first example of the structurally characterized coordination compound containing hexahydromandelic acid anions.

The dependence of valence molecular orbital (MO) energies is obtained for AnO₂ (An = Th–Lr). The energies are calculated by the relativistic discrete variation (RDV) method depending on atomic number Z. Depending on the characteristics of the complex structures of theoretical and available experimental X-ray photoelectron spectra (XPS) of valence electrons in the binding energy range from 0 eV to ~50 eV, the features of the AnO₂ electronic structures are analyzed. This structure appears in the XPS spectra mainly due to the formation of both outer valence MOs from 0 eV to ~15 eV and inner valence MOs (IVMO) from ~15 eV to ~50 eV. The IVMO formation efficiency (experimental observation) characterizes the chemical bond features of actinide dioxides. Good agreement is reached between the calculated and available experimental XPS spectra of valence electrons. It allows us to understand the features of the chemical bond nature and the structures of XPS spectra of valence electrons in the AnO₂ series. Significant covalence effects are observed in AnO₂, which are caused by overlapping with ligand orbitals of not only An 6d but also 6p and 5f atomic orbitals.

This study reports the synthesis and characterization of a nickel complex. Its structure was determined to be octahedral, with the nickel ion coordinated by two cis nitrogen atoms and four oxygen atoms (two from the ligand, two from water molecules). Notably, the aliphatic OH of the ligand did not participate in coordination. Hirshfeld surface analysis was conducted to examine intermolecular interactions, the results confirmed the presence of π-π interactions related to planar stacking, the sum of results provide valuable insights into the crystal packing and structural stability of the complex.We have also investigated the electrochemical behavior of the ligand and the complex by cyclic voltammetry.

The synthesis of single-phase hexaferrite BaFe_12–xIn_xO₁₉, in the crystal structure of which indium partially substitutes for iron (x = 0–2.25), is described together with its crystal structure, chemical composition, and initial magnetic permeability. It is revealed that 1400 °C is the optimal temperature to obtain indium-substituted barium ferrite. Studies of the temperature dependences of the initial magnetic permeability of these ferrites show that as the indium concentration increases, the Curie temperature monotonically decreases. Unit cell parameters of the obtained solid solutions monotonically increase with increasing indium concentration.

The development of spintronics, a key field of modern materials science, requires the search for new materials and their combinations for the effective control of spin transport. We report a theoretical study of new magnetic heterostructures based on the Co₂FeGe_1/2Ga_1/2 half-metallic Heusler compound (CFGG) and monolayers of tungsten dichalcogenides WX₂ (X = S, Se, Te). Structural, magnetic, and electronic properties of the WX₂/CFGG interface are analyzed by the DFT method for both Co- and FeGeGa-terminations of the substrate. The obtained results demonstrate stable ferromagnetism in the CFGG substrate, high level of spin polarization, and the increase of local magnetic moments at the interface. For example, the obtained tunneling magnetoresistance values are as high as 112% and 157% for Co-terminated WS₂/CFGG and WSe₂/CFGG, respectively. These results indicate that WX₂/CFGG based magnetic heterostructures are highly promising as a base for spin filters and other spin devices.

Heteroleptic mononuclear cobalt(III) complexes of the [L–Co^III(bipyr)]⁺ cation type are obtained for the first time by coordinating lower-rim 1,3-disubstituted calix[4]arene derivatives 2-3 (L) with coordinating salicylideneamine sites, 2,2′-bipyrimidine (bipyr), and cobalt(II) cations. Their structures are determined by single crystal X-ray diffraction. It is shown that regardless of the presence of an azophenyl substituent at the para-position of the coordinating fragment, a similar structural motif is observed that is featured by the cobalt(III) atom coordinated to two chelate N,O-coordinating centers of the macrocyclic ligand and two bipyr nitrogen atoms, forming a distorted octahedral trans-N₄O₂ coordination sphere. For the complex based on 3, containing azophenyl moieties, the 2D porous supramolecular architecture is obtained that is formed by numerous intermolecular CH/π- and π-stacking interactions.

Structural parameters of Mg₂NA (A = F, Cl, Br, I) crystals with antichalcopyrite and anti-LiFeO₂ structures are determined and their vibrational spectra are studied using the density functional theory (DFT). It is shown that that the chloride, bromide, and iodide spectra contain features in the form of acoustic branches with imaginary frequencies characteristic for unstable structures. For Mg₂NF, the energetically optimal path of the structural transition to the stable state is calculated. The transition path contains additional intermediate minima, for which symmetry and parameters of the corresponding crystal structures are determined. On this basis, a mechanism of a structural phase transition to Mg₂NF is proposed.

Crystal structures of [1,2,5]selenadiazolo[3,4-d]pyrimidin-7(6H)-one (1), [1,2,5]selenadiazolo[3,4-d]pyrimidin-5,7(4H,6H)-dione (2) as solvates with pyridine, and individual 1 are determined by single crystal X-ray diffraction. In all cases, 1 and 2 molecules form planar π-stacked dimers with supramolecular synthon [Se⋯N]₂. The structures of compound 1 have shortened Se⋯N contacts involving the nitrogen atom of the pyrimidine ring. Oxygen atoms of C=O fragments and nitrogen atoms of pyridine solvate molecules form hydrogen bonds with N–H-fragments.

The [Cu(phendione)LBr₂]·C₂H₅OH complex (1) is prepared by the interaction of copper(II) bromide with 1,10-phenanthroline-5,6-dione (phendione) and 1-(1H-benzamidazole-1-ylmethyl)-1H-1,2,3-benzotriazole (L). The compound is characterized by elemental analysis, powder XRD, and IR spectroscopy. It is shown by single crystal XRD that the complex is mononuclear, and the environment of its central atom is formed by two bromide anions, three nitrogen atoms of the 1,10-phenanthroline-5,6-dione chelating ligand, and the L ligand coordinated in a monodentate mode by a nitrogen atom of the benzimidazole ring. The stability of 1 in an ethanol/DMSO mixture and in a phosphate-buffered saline for 48 h is studied. The cytotoxicity of the ligands and the copper(II) complex is studied on the lung adenocarcinoma cell line (A549) and non-tumor human lung fibroblasts (MRC5). It is shown that the complex exhibits cytotoxic activity on both cell lines and exerts selective action against A549 cells.

Two polymorphs of 2,7-bis(3-(1H-imidazol-1-yl)propyl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (L) and a one-dimensional (1D) cobalt coordination polymer of L (Co-Poly) have been successfully synthesized and reported. These polymorphs were crystallized using different solvent systems-polymorph 1 in dimethylformamide (DMF) and polymorph 2 in a mixture of DMF and methanol. Their solid-state structures were determined through single crystal X-ray diffraction. These compounds were characterized with spectroscopic tools like Powder X-ray Diffraction (PXRD) and elemental analysis. Various supramolecular interactions, including C–H⋯O, C–H⋯N, and C–H⋯π interactions, were identified in both polymorphs, with additional π⋯π interactions observed in polymorph 2. In the case of the coordination polymer, the Co(II) center adopts a distorted octahedral coordination environment. The polymer is synthesized under solvothermal conditions, with its solid-state structure stabilized by intra-ligand π⋯π stacking interactions. These supramolecular interactions collectively contribute to the formation of a three-dimensional (3D) supramolecular architecture in the solid-state structures of all the compounds. Additionally, 2D-fingerprint (2D-FP) and Hirshfeld surface analysis (HSA) were employed to confirm the 2D-network-packed crystal lattice interactions. Crystal void calculations indicate that all compounds exhibit mechanical stability in the solid state.