Search Results (2,596)

We report here a thorough study concerning the acylation reaction products of 8-hydroxyquinoline with 2-chloroacyl chloride, with new insights and clarifications in respect to the obtained products brought by NMR and X-ray studies. According to the reaction conditions we employed, three compounds could be obtained: 1-(2-chloro-2-oxoethyl)pyridin-1-ium chloride 10, 8-hydroxyquinoline hydrochloride 11, and the acylated product 8-(2-chloroacetoxy)quinolin-1-ium chloride 12. A certain influence of the catalyst and the used solvent was observed, and feasible explanations for product formations were furnished. The structure of the compounds was proved by using ¹H- and ¹³C-NMR spectra as well as single-crystal X-ray diffraction studies for compounds 12 and 11. According to X-ray crystallography, compounds 11 and 12 have a planar structure and exhibit an ionic crystal structure crystallized as a hydrochloride salt of the corresponding organic base. The crystal structures of both compounds are stabilized by intermolecular hydrogen bonds and π-π stacking interactions. In the crystals of compounds 11 and 12, the structural components are interconnected by a system of intermolecular hydrogen bonding, and a similar one-dimensional array is formed via hydrogen bonding and π-π stacking. The further assembling of the structure for 12 and 11 occurs with the formation of a three-dimensional supramolecular network. Full article

As a part of our research on the presence of conglomerates among the aryl benzyl sulfoxides, racemic-benzimidazolyl pentafluorobenzyl sulfoxide was synthesised, and its crystal structure was determined by a single crystal X-ray diffraction experiment. The main interactions building up the crystal structure were recognised and compared with those of similar compounds. Since the crystal structures of racemic and enantiopure benzimidazolyl pentafluorobenzyl sulfoxides are different, the presence of a conglomerate is excluded in the present case. Full article

The new compound Cs₂Cu₂[V₄O₁₂]Br₂ was synthesized by the chemical vapor transport reaction method. Structural data obtained by single-crystal X-ray diffraction in the temperature range 100–700 K revealed three successive (with decreasing temperature) structural phase transitions: from the high-temperature aristotype structure I4/mmm (>550 K) to the polymorph P4/mnc (550–340 K), then to P4/m (340–300 K), and finally to the low-temperature phase I4/m (<300 K). The crystal structure of the new compound is based upon the Cu₂[V₄O₁₂]⁰ layers, consisting of four-membered rings of corner-sharing vanadate tetrahedra linked by CuO₄ squares. Analysis of the structural evolution with increasing temperature shows that the entire sequence of phase transitions is governed by the rotation of the [V₄O₁₂]⁴⁻ rings about the z axis. Full article

Wollastonite-1A from Băița Bihor occurs in distal calcic skarns developed in the contact zone of a mainly granodioritic batholith, of Upper Cretaceous age, with Mesozoic limestones and dolostones. Wollastonite generally occurs in the inner part of metasomatic columns, in monomineralic skarns or associated with grossular and molybdenite-2H as ore mineral. The physical properties (i.e., refraction indices α = 1.616, β = 1.629, and γ = 1.631, 2V_α = 39° and density D_m = 2.922(3) g/cm³) are typical for a term close to the stoichiometry, which is confirmed by the chemical analysis. The chemical structural formula of the analyzed wollastonite-1A is (Ca_1.000Mg_0.002Mn_0.001Fe_0.001)(Al_0.004Ti_0.001Si_0.994)O₃, which closely approximates the ideal CaSiO₃. The Gladstone–Dale compatibility indices account for an excellent agreement between physical and chemical data. The mineral can be satisfactorily refined as triclinic, space group $P\overline{1}$, with R₁ = 0.0678 and cell parameters a = 7.9233(3) Å, b = 7.3203(3) Å, c = 7.0651(3) Å, α = 90.053(3)°, β = 95.208(3)°, γ = 103.384(3)°. Both the IR and Raman spectra principally reveal bands related to vibrations of bridged and non-bridged oxygens pertaining to SiO₄ structural tetrahedra. At Băița Bihor, wollastonite-1A is part of the prograde paragenesis, marked by a peak temperature of 550–600 °C. Full article

Two trinuclear cobalt (Co₃)-based metal–organic frameworks, [Co₃(CHDC)₃(py)₄] (2; CHDC = trans-1,4-cyclohexanedicarboxylate, py = pyridine) and [Co₃(CHDC)₃(mpy)₂]· 2DMF (3; mpy = 4-methylpyridine, DMF = N,N-dimethylformamide), were successfully prepared via the solvothermal reactions of Co(NO₃)₂·6H₂O, trans-1,4-cyclohexanedicarboxylic acid, and py/mpy in DMF solution. Single crystal X-ray diffraction analyses revealed that the Co₃-secondary building units (SBUs) in 2 and 3 adopt Co^octahedral···Co^octahedral···Co^octahedral and Co^tetrahedral···Co^octahedral···Co^tetrahedral coordination environments, respectively, and are connected by six CHDC linkers to form two-dimensional sheet structures with a triangular lattice. The structural differences of these Co₃-SBUs led to clear differences in the magnetic properties and electronic spin states of 2 and 3; temperature-dependent magnetic susceptibility measurements revealed that 2 and 3 exhibited antiferromagnetic and ferromagnetic interactions, respectively, within the Co₃-SBUs. These experimental magnetic results are consistent with the density-functional theory calculations of the model structures of Co₃-SBUs, which indicate that the most stable spin states are S = 3/2 for 2 and S = 9/2 for 3. Full article

A novel derivative from carotene-type sesquiterpene, (1S,2R,3aR,6S,8aS)-1-isopropyl-3a,6-dimethyldecahydroazulene-1,2,6-triol (1), was successfully isolated from filamentous fungus Trichoderma virens NBRC 31959. The structure and molecular formula of 1 were determined by interpretation of 1D and 2D NMR and HRMS data. The absolute configuration was established unambiguously by single-crystal X-ray diffraction, with the Flack parameter supporting the assignment. This study adds to the chemical diversity of sesquiterpene-type CAF603 derivatives of Trichoderma virens. Full article

(Li_0.4Co_0.2Ni_0.2Cu_0.2Zn_0.2)WO₄ high-entropy ceramics were prepared by a conventional solid-state reaction route. This study thoroughly explores the interrelationships between their crystal structure, bond properties, and microwave dielectric characteristics. X-ray diffraction analysis verified that all specimens crystallized in a single-phase ZnWO₄-type structure. According to Rietveld refinement of the XRD data, the lattice parameters are affected by the ionic radii of the constituent elements, confirming their dissolution and random distribution at Zn sites. Relative density exhibited a strong dependence on sintering temperature. Bonding analysis highlights the crucial role of the W–O bond in governing the dielectric response of the (Li_0.4Co_0.2Ni_0.2Cu_0.2Zn_0.2)WO₄ (LCNCZW) ceramics. Moreover, sinterability can be improved through optimizing the sintering process. Notably, samples sintered at 850 °C attained suitable dielectric performance, characterized by εᵣ = 11.697 ± 0.204, Q × f = 23,851 ± 0.126 GHz, and τ_f = 21.335 ± 0.232 ppm/°C. These results demonstrate that high-entropy design can effectively improve the sinterability and microwave dielectric performance of wolframite-type ceramics, offering a promising strategy for the development of microwave dielectric ceramics for communication devices. Full article

Metal-chalcogenide compounds with perovskite-type compositions have drawn increasing attention for their optical properties for solar energy conversion. Herein, a new α-type polymorph of the ternary sulfide SrHfS₃ is described, crystallizing in the NH₄CdCl₃ structure type. The yellow-colored plate-shaped crystals were synthesized at 1173 K using an elemental tin flux in an evacuated sealed tube. Its crystal structure was characterized at room temperature using single crystal X-ray diffraction to form in the orthorhombic Pnma space group, with the refined cell parameters of a = 8.5041(4) Å, b = 3.8004(2) Å, c = 13.8935(6) Å, and V = 449.02(4) ų. The structure comprises five independent crystallographic sites, having one Sr, one Hf, and three S sites. The structure can be described as containing one-dimensional chains of distorted HfS₆ octahedra extending down the b-axis to form ${\displaystyle \genfrac{}{}{0pt}{}{1}{\infty }}[$HfS₃]²⁻ strips of edge-sharing octahedra. The Sr atoms act as charge-balancing space fillers in the structure. High-purity bulk samples of α-SrHfS₃ could be prepared for measurement of its bandgap by optical diffuse-reflectance spectroscopy, showing a direct bandgap of 2.1(1) eV. Results of electronic structure calculations are consistent with this bandgap and type. The conduction and valence band edges stem from the respective empty Hf d-orbitals and the filled S p-orbital states. In summary, crystal growth of the α-type polymorph of SrHfS₃ has been demonstrated using a Sn flux approach, which can facilitate future broader synthetic explorations at lower temperatures. Full article

Treatment of palladium precursor Pd(PPh₃)Cl₂ with equivalent arylfluorodithiophosphato ligand [PPh₄][(4-EtO-C₆H₄)FPS₂] in chloroform at reflux resulted in a mononuclear palladium(I)–sulfur complex cis-[Pd(PPh₃)₂{κ²-S,S′-(4-EtO-C₆H₄)FPS₂}]. This complex was characterized by UV-Vis and IR spectroscopic analysis, thermogravimetric analysis, and XPS analysis, and its molecular structure has been established by single-crystal X-ray diffraction. SBA-15, as a mesoporous material, was selected as a mesoporous silica substrate to further form a homogeneous catalyst, Pd@SBA-15, which has been characterized by IR spectroscopy, electron microscope and N₂ adsorption–desorption test. In addition, the catalytic activity of Pd@SBA-15 for the Suzuki–Miyaura cross-coupling reaction was also investigated. Full article

Synthetic derivatives of testosterone known as 17α-alkylated anabolic–androgenic steroids have been developed to retain anabolic effects while enabling oral administration. Here, we present newly identified hydrated solid forms of three agents: oxandrolone hemihydrate (C₁₉H₃₀O₃·0.5H₂O), fluoxymesterone hydrate (C₂₀H₂₉FO₃·H₂O), and methandienone hemihydrate (C₂₀H₂₈O₂·0.5H₂O). Their crystal structures were determined using single-crystal X-ray diffraction, supplemented by powder X-ray diffraction and thermal analyses. Computational methods were employed to investigate molecular interactions and crystal packing. Lattice energy evaluations revealed that the hydrated forms are energetically less stable than their anhydrous counterparts, with significantly less negative values (e.g., −113.4 kJ/mol for oxandrolone hemihydrate vs. −164.4 kJ/mol for the anhydrous form). Energy decomposition analysis indicates that while water molecules participate mostly in electrostatic-driven hydrogen bonding, they disrupt the dispersive packing efficiency found in the anhydrous phases. Specifically, intermolecular interaction energies show that host–host hydrogen bonds (up to −62.2 kJ/mol in oxandrolone) dominate over weaker host–water couplings (−8.9 to −34.9 kJ/mol). The newly reported crystal structures contribute to the expanding catalog of solid-state forms for 17α-alkylated steroids and provide important details regarding their metastable nature and the dehydration-driven phase transformations observed under climatic stress conditions. Full article

Microorganisms provide critical lead compounds for drug development, yet most biosynthetic gene clusters remain silent under standard culture conditions. The OSMAC strategy activates these clusters by adjusting cultivation parameters, thereby enabling the discovery of novel compounds from a single strain. Here, we applied OSMAC to explore the metabolic potential of the soft coral-derived fungus Aspergillus sclerotiorum SCSIO 41031. Three different culture media were employed for the large-scale fermentation process. After isolation by chromatography, the compounds were structurally characterized using NMR, MS, and X-ray single-crystal diffraction, and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. In total, three new compounds, named 6,6′-diacetyl-1,1′-dihydroxy-3,3′-dimethoxydibenzyl ether (1), esterwortmannolol (17) and pestalpolyol I (20), along with 19 known compounds (2–16, 18–19 and 21–22) were obtained. This study validates the efficacy of the OSMAC strategy and underscores that A. sclerotiorum SCSIO 41031 serves as a valuable resource for producing structurally diverse natural products with potent biological activities. Full article

The structural characterization of GG-rich DNA sequences in presence of metal ions provides essential insight into quadruplex stability and ion-dependent conformational specifics. We report the crystal structure of the GG-quadruplex formed by the sequence GGGGTTTTGGGG in the presence of Zn²⁺, K⁺, and Na⁺. It was deposited in the RCSB Protein Data Bank under the accession code 9FTA. The structure was determined by single-crystal X-ray diffraction at a resolution of 2.49 Å in the space group P2₁2₁2₁. It reveals a parallel-stranded, two-G-tetrad stabilized by K⁺ ions within the central channel, while Na⁺ and Zn²⁺ occupy peripheral and groove-associated sites. Zn²⁺ ions are engaged in noncanonical coordination interactions with phosphate oxygens and structured water molecules, contributing to lattice stabilization and subtle adjustments in groove dimensions. The T4 loop forms a compact, ordered motif that contributes to crystal packing rather than intramolecular G4 stabilization. The presence of mixed cations produces a sole lattice architecture mediated by ions that provides structural insight into how bivalent and monovalent metals mutually modulate G-quadruplex topology. These results suggest a basis for understanding the specific ion effects on G4 structures and may direct the design of metal open DNA architectures. Full article

The self-assembly of a novel synthesized chiral dipeptide, Boc-p-nitro-L-phenylalanyl-tyrosine, into supramolecular structures is investigated by optical absorption and photoluminescence spectroscopy as well as single crystal X-ray diffraction. The compound is a diphenylalanine derivative belonging to a family of aromatic dipeptides that spontaneously self-organize into nanostructures through molecular recognition. The dipeptide exhibits several step-like peaks in its absorption band, indicative of self-assembly into quantum-confined nanostructures. In contrast, the parent Boc-p-nitro-L-phenylalanine amino acid lacks these features, indicating that the tyrosine residue favors quantum-confined self-assembly. Crystal structure determination reveals distinct packing styles: Boc-p-nitro-L-phenylalanine forms two-dimensional hydrogen-bonded layers, while the related p-nitro-free Boc-L-phenylalanyl-tyrosine dipeptide organizes into a 3D helical columnar architecture, driven by the additional hydrogen-bonding capacity of the peptide bond and tyrosine hydroxyl group, which favors the formation of a channel-type tetragonal architecture network over the planar sheets of the monomer. Furthermore, the introduction of a tyrosine residue into the Boc-p-nitro-L-phenylalanine molecule alters its supramolecular assembly, as the dipeptide Boc-p-nitro-L-phenylalanyl-tyrosine crystallizes as a monohydrate. The water molecule present in the structure acts as a bridge, participating in a hydrogen-bonding network between the tyrosine hydroxyl groups of neighboring columns through intermolecular interactions. Full article

This work reports the isolation and structural characterization of 1-(2-aminophenyl)-3-(4-pyridyl)-3-hydroxy-1-propanone (1), a β-hydroxyketone intermediate that crystallized unexpectedly during the base-catalyzed aldol condensation of 2-aminoacetophenone with pyridine-4-carbaldehyde, a reaction intended to afford the corresponding pyridyl chalcone (2). The formation of (1) highlights the sensitivity of Claisen–Schmidt reactions to the electronic and steric features of the substrates and to the applied reaction conditions. Single-crystal X-ray diffraction unambiguously confirmed the molecular structure of (1), revealing a hydrogen-bonding network involving the amino, carbonyl, and β-hydroxyl functionalities. These interactions contribute to the solid-state stabilization of the β-hydroxyketone and hinder its dehydration to chalcone (2). The present results provide experimental insight into the mechanistic landscape of aldol condensations and emphasize the relevance of isolable intermediates as structurally defined precursors for further synthetic transformations. Full article

Two Zn(II) coordination compounds based on glaucine-derived Schiff bases were synthesized and investigated as potential materials for dye-sensitized solar cells (DSSCs). The structures of all compounds were established by X-ray diffraction analysis and quantum chemical modeling (DFT/TD-DFT). Their photophysical properties (absorption and luminescence spectra in solution and the solid state), electrochemical characteristics, and photovoltaic parameters in DSSC devices were studied. The highest power conversion efficiency (PCE ~5.18%) was demonstrated by the free ligands, which is attributed to their favorable absorption spectrum and optimal alignment of energy levels relative to the conduction band of TiO₂ and the redox couple of the electrolyte. The Zn(II) coordination compounds exhibited significantly lower efficiency (~2.1%). Impedance spectroscopy results indicated more efficient charge transfer at the TiO₂/dye/electrolyte interface for the organic derivatives. Full article