Vol 60, No 2 (2019)

The substitution of A and B cations in SrFeO₃ and SrCoO₃ oxides with the perovskite structure ABO₃ is studied using ab initio DFT calculations in terms of their effect on the structural and electronic properties of these compounds. It is shown that the main effect of Nb, Ta, Mo, W substituents refers to the local increase of the cohesive energy (the decrease of the total energy) of the oxides. This change may reach 10 kJ/mol per 1% of the B dopant.

Conformational stabilities, molecular structures, and vibrational frequencies of 2- and 3-pyrrolecarboxaldehyde are investigated using the density functional theory at the B3LYP/6-311++G** level of theory. From the computations, cis-2-pyrrolecarboxaldehyde is 3.57 kcal/mol thermodynamically more preferable than trans-2-pyrrolecarboxaldehde, and trans-3-pyrrolecarboxaldehyde is found to be more preferable than their cis conformer with an energy difference of 0.30 kcal/mol. The computed geometrical parameters are in agreement with the available experimental data. The effect of solvents on the conformational stability of both 2- and 3-pyrrolecarboxaldehydes in nine different solvents are investigated using the polarizable continuum model. The highest occupied and lowest unoccupied molecular orbitals, infrared vibrational wavenumbers and intensities, and molecular electrostatic potentials are reported. Reliable vibrational assignments are proposed based on the potential energy distribution using the VEDA4 program. The simulated vibrational IR spectra are plotted and compared with the available experimental FT-IR spectrum.

A three-dimensional quantitative structure-activity relationship (3D-QSAR) model of 45 sulfonylurea herbicidals is established using the Topomer comparative molecular field analysis (Topomer CoMFA). The results show that correlation coefficient (q²), non-cross-validation correlation coefficient (r²), and external validation (Q_ext²) are 0.884, 0.908, and 0.857 respectively. The biological evaluation demonstrates that the obtained model has the excellent external predictive ability and good estimation stability. The methodology of the fragment-based drug design is also applied to design new sulfonylurea herbicides using the Topomer Search technology. Compound 11 with the highest activity is chosen as the template molecule. By adding three substitutional groups selected from the ZINC database to the template molecule, 36 new compounds with an activity more than that of the template molecule are obtained. The template molecular and designed compounds are used to explore the binding relationship of the ligands with the receptor protein in molecular docking. The result shows that hydrogen bonding interactions form between the ligands and amino acid residues.

A one-pot and neat reaction procedure is used for the synthesis of CH₂-{cyclo-C₆H₁₀)-NCH-C₆H₄-OH-2}₂. ¹H NMR shows a mixture of ZE and EE isomers in a ratio of 2:0.9. The EE isomer is easily isolated as crystals suitable for the X-ray analysis. ¹H,¹³C NMR and UV-visible spectra of the title compound are studied in different solvents. The crystal structure shows intramolecular H bonds as an EE isomer. The molecule lies about a twofold symmetry axis, passing through the C1 atom. The cyclo-hexyl ring C2-7 shows a chair conformation, with both C2-C1 and C5-N1 bonds in equatorial orientations. The phenolic hydrogen atom H1a forms a good hydrogen bond with the imino nitrogen atom N1 and the N1-C8 bond is short, as expected for a double bond (1.265(4) Å).

Spectroscopic properties and DFT studies (optimized geometry, vibrational band assignment, MEP analysis, frontier molecular orbitals, NLO effects, and thermodynamic functions) of 5-ethylsulphonyl-2-phenyl-benzoxazole are reported. The DFT calculations are performed by Hartree-Fock (HF) and B3LYP and BYLP functionals with the 6-311++G(d,p) basis set. The compared frequencies are compatible in both theoretical and experimental spectra. HOMO and LUMO levels have been defined. The first order hyperpolarizability of 5-ethylsulphonyl-2-phenyl-benzoxazole is calculated and the promising application in OLED devices is identified for the compound.

The common “template” of datolite and okayamalite structures is a column-ribbon formed by alternating empty and Si occupied oxygen tetrahedra interconnected by common edges. The columns consolidate with their environment into crystalline structures largely due to the influence of the local symmetry of SiO₄ and BO₄ tetrahedra. As a result, mirror symmetry pseudo-planes of monoclinic datolite transform into okayamalite m planes; the pseudo-axis \(\bar 4\) becomes the principal axis, whereas both structures contain glide planes and cation sublattices close in size.

The [Cu₈(S-mal)₄(bptc)(H₂O)₁₂] · 0.5H₄bptc · 7.5H₂O coordination polymer is obtained by heating the copper(II) nitrate, S-malic acid (H₃mal), and biphenyl-3,3′,5,5′-tetracarboxylic (H₄bptc) acid solution in the water-N,N-diethylformamide mixture. The crystal structure is determined from XRD data. The compound has a three-dimensional homochiral framework with channels filled by crystallization molecules of tetracarboxylic acid and water. The composition and structure of the coordination polymer obtained are confirmed by X-ray powder diffraction, IR spectroscopy, thermogravimetric analysis, and elemental analysis.

The heating of a mixture of as-precipitated scandium hydroxide and tetrafluoroterephthalic acid in ethylene glycol leads to the formation of the complex [Sc₂(HOCH₂CH₂OH)₄(tFBDC)₃]·2HOCH₂CH₂OH (tFBDC²⁻ = tetrafluoroterephthalate) (1). According to the X-ray data, compound 1 is a chain coordination polymer. Sc(III) cations and tFBDC²⁻ anions form double chains (ribbons). The coordination number of Sc(III) is completed to seven by ethylene glycol molecules acting as chelate ligands. There is a complex system of hydrogen bonding interactions induced by oxygen atoms of carboxylic groups of perfluorinated ligands and coordinated and lattice ethylene glycol.

A cluster complex with the composition (Bu₄N)₄[Re₆S₈(CC₆H₄-p-NC₂)₆] having terminal phenoxide ligands is obtained by the reaction of (Bu₄N)₄[Re₆S₈Cl₆] with silver p-nitrophenolate. The compound crystallizes in the orthorhombic space group Pccn with the following unit cell parameters: a = 19.507(2) Å, b = 31.645(3) Å, c = 19.237(2) Å, V = 19.237(2) ų, Z = 4, d_calc = 1.774 g/cm³.

Molecular and crystal structure of the antioxidant 4-[3,3-bis(3,5-di-tert-butylphenyl-4- hydroxybenzyl)-3H-indole-2-ilmethylene]-2,6-di-tert-butylcyclohex-2,5-dienone (1) and (E)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N′-((1S,4R)-1,7,7-trimethyl-bicyclo[2.2.1]heptane-2-ylidene)propane hydrazide (2) is studied. It is shown that sterically hindered phenols do not form hydrogen bonds in any of these molecules. In crystal 2, amide groups form a pseudo-centrosymmetric dimer due to N-H…O hydrogen bonds. The chiral camphene basis of molecule 2 prevents the formation of a centrosymmetric supramolecular synthon that usually appears in racemic compounds with amide groups, while the pseudo-centrosymmetric geometry of propane hydrazide chains hinders packing within the space group of the second-order rotational symmetry. As a result, molecules 2 crystallize into non-centrosymmetric crystals with two independent molecules.

A cobalt(II) complex with 2,2′-bipyridine and phthalate ligands of the composition [Co(bpy)(Hpht)(H₂O)₃][Co(bpy)(pht)(H₂O)₂]Cl·2H₂O (bpy: 2,2′-bipyridine; Hpht, pht: o-phthalate anions) are synthesized and characterized by FT-IR and electronic spectroscopy and single crystal X-ray diffraction. The compound crystallizes in the triclinic system, space group, Z = 2 with a = 11.998(5), b = 13.956(5), c = 14.313(5) Å, α = 112.33(5), β = 95.067(5), γ == 109.166(5)°. The structure consists of a cationic complex unit [Co(bpy)(Hpht)(H₂O)₃]⁺, a neutral complex unit [Co(bpy)(pht)(H₂O)₂], a chloride anion, and two lattice water molecules. The intermolecular O-H⋯O hydrogen bond links two independent Co(II) complexes in the crystal structure, forming a supramolecular dimer. The dimers in the crystal form a 2D layered network structure via weak supramolecular π-π stacking, C-H⋯O, C-H⋯Cl, and O-H⋯Cl hydrogen bonding interactions. The thermal behavior of the compound is investigated.

In the original publication the name of one of the authors had been misspelled and the authors had been listed in the wrong order. The correct spelling of the names of the authors and their order is: M. Masoudinia, A. Bagheri ghomi.