Acta Crystallographica Section C Structural Chemistry最新文献

A novel mononuclear cobalt(II) complex, diaquabis[4-(4-carboxyphenoxy)benzoato-κO]bis{4-[3-(pyridin-4-yl)-1H-pyrazol-5-yl]pyridine-κN}cobalt(II), [Co(C₁₄H₉O₅)₂(C₁₃H₁₀N₄)₂(H₂O)₂] or [Co(Hoba)₂(bpp)₂(H₂O)₂] [H₂oba 4,4'-oxydibenzoic acid and bpp is 4,4'-(1H-pyrazole-3,5-diyl)bipyridine], was successfully synthesized via a hydrothermal approach. In this compound, the central Co^II atom exhibits a hexacoordinate octahedral geometry. The complex molecules are interconnected through hydrogen-bonding interactions, constructing a three-dimensional supramolecular framework. UV-Vis absorption spectroscopy revealed two distinct absorption bands at 274 and 367 nm. The third-order nonlinear optical properties were investigated using Z-scan measurements. The results demonstrated pronounced negative refraction behaviour with a nonlinear refractive index n₂ of -1.47 × 10^-12 m² W^-1 and a third-order susceptibility χ⁽³⁾ of 5.62 × 10^-7 esu. These remarkable optical characteristics suggest that this cobalt(II) complex is a potential candidate for advanced photonic applications demanding high-performance third-order nonlinear optical materials.

A novel Co^II-based coordination polymer, poly[[μ-4,4'-bis(2-methyl-1H-imidazol-1-yl)-1,1'-biphenyl-κ²N³:N^3'](μ-5-nitrobenzene-1,3-dicarboxylato-κ²O¹:O³)cobalt(II)], [Co(C₈H₃NO₆)(C₂₀H₁₈N₄)] or [Co(NO₂-BDC)(4,4'-BMIBP)]_n, (I), was synthesized successfully via a hydrothermal reaction. The synthesis employed 5-nitrobenzene-1,3-dicarboxylic acid (NO₂-H₂BDC) as the organic linker, 4,4'-bis(2-methyl-1H-imidazol-1-yl)-1,1'-biphenyl (4,4'-BMIBP) as the N-donor auxiliary ligand and cobalt(II) nitrate hexahydrate as the metal source. Structural characterization revealed that (I) crystallizes in a unique three-dimensional framework featuring a threefold parallel interwoven dmp network topology. Photoluminescence studies demonstrated that (I) exhibits remarkable sensitivity and selectivity for the detection of nitrofurazone (NFZ) in aqueous solution. Furthermore, systematic investigations were conducted to elucidate the potential fluorescence quenching mechanisms of (I) toward NFZ.

3D electron crystallography has emerged as a method with great potential for the structure determination of small molecules and macromolecules complementing traditional single-crystal X-ray crystallography and powder X-ray diffraction (PXRD). It offers the unique capability of determining the structures of small molecules and macromolecules from micro- and nanocrystals. In this study, using 3D electron diffraction (3D ED), we determined the single-crystal structure of commercially sourced arginine directly from its bottle. The 3D ED analysis of micro-sized single crystals identified two distinct forms: the L-arginine enantiomer and the racemic mixture DL-arginine. At the time of writing, neither the Cambridge Structural Database nor the Crystallographic Open Database contain a single-crystal structure of isolated L-arginine (sum formula C₆H₁₄N₄O₂), which has been solved in this work by 3D ED. We also present a comparison of the structures of these molecules solved by 3D ED and PXRD.

A novel cobalt(II) coordination polymer, poly[diaqua[μ-4,4'-({2,2-bis[(pyridin-4-yloxy)methyl]propane-1,3-diyl}bis(oxy))dipyridine]bis(μ-naphthalene-1,4-dicarboxylato)dicobalt(II)], [Co₂(C₁₂H₆O₄)₂(C₂₅H₂₄N₄O₄)(H₂O)₂]_n or [Co₂(1,4-nda)₂(PDP)(H₂O)₂]_n, (1), has been successfully synthesized through the hydrothermal reaction of CoCl₂·6H₂O with naphthalene-1,4-dicarboxylic acid (1,4-ndaH₂) and 4,4'-({2,2-bis[(pyridin-4-yloxy)methyl]propane-1,3-diyl}bis(oxy))dipyridine (PDP). Compound (1) features a robust three-dimensional framework intricately interconnected by 1,4-nda^2- and PDP spacers. Topological analysis identifies this architecture as a (4,4)-connected net with point symbol {3⁶·4⁶·5¹³·6³}. The UV-Vis spectrum displays an intense ligand-centred π→π* transition band at 305 nm. Z-scan measurements at 532 nm (7 ns pulse) demonstrate strong reverse saturable absorption activity with an absorption coefficient of 2.68 × 10^-7 m W^-1. This compound is anticipated to be a promising candidate for applications in third-order nonlinear optics.

The azo dye methyl 2-{2-[(E)-2-oxo-1,2-dihydronaphthalen-1-ylidene]hydrazin-1-yl}benzoate, C₁₈H₁₄N₂O₃, was synthesized and subjected to an extensive experimental and theoretical study. Crystallizing in the monoclinic space group P2₁/c, the compound was analyzed using X-ray diffraction and density functional theory (DFT) calculations with the B3LYP functional and 6-311G(d,p) basis set. The results demonstrated a strong correlation between the experimental and theoretical geometrical parameters, with one of the tautomeric forms (denoted K, the NH/C=O tautomer) showing greater stability. Hirshfeld surface analysis revealed significant H...H, C...H and O...H interactions. Energy framework analysis indicated that dispersion forces play a crucial role in crystal stability. The vibrational and UV spectra were consistent between the experimental and theoretical data. The small energy gap in the K tautomeric form suggests higher polarizability, making it a promising candidate for optically active materials. Chemical reactivity descriptors highlighted the enhanced reactivity of the K tautomer. Reduced density gradient (RDG) analysis showed stronger hydrogen bonding in the second tautomer (denoted E, the N=N/C-OH tautomer), while molecular electrostatic potential (MEP) analysis identified high electron density around the O atoms, suggesting electrophilic sites. The high first-order hyperpolarizability of the compound points to potential nonlinear optical (NLO) applications. Biological studies suggested potential antipyretic activity, with COX-2 identified as a promising target for inhibition due to its strong binding affinity and effectiveness. These findings support further investigation into COX-2 inhibition.

The crystal structure of magnesium nickel tetraboride, MgNiB₄, was solved and refined based on single-crystal X-ray diffraction data. MgNiB₄ crystallizes in the Pbam space group [a = 5.8791 (2), b = 11.2982 (5) and c = 3.2771 (1) Å] and is isostructural with the YCrB₄ type. The MgNiB₄ and YCrB₄ structures both belong to the AlB₂-type structural family, for which the formation of 6₃-nets by B atoms is typical. In MgNiB₄, B atoms form five- and seven-membered ring nets, which result from a rearrangement of the 6₃-nets. Strong covalent B-B interactions are established according to electronic structure calculations using the tight-binding linear muffin-tin orbital atomic spheres approximation (TB-LMTO-ASA) method. The maximum hydrogen absorption by the MgNiB₄ alloy reached 3.75 wt% H₂.

The crystal structure of the sodium aluminium difluorosulfate NaAl(SO₄)F₂ has been determined from laboratory powder diffraction data. Its characterization allows for improving the monitoring of aluminium industrial production starting from cryolite. It is characterized by a perovskite single layer formed by the fluorine corner-sharing of [AlF₄O₂] octahedra with SO₄ groups, and sodium as the interlayer content. This could be the n = 1 member of a possible new family of 2D perovskite materials AM_n(SO₄)F_3n-1 (A⁺ = Na, Li; M³⁺ = Al, Fe, V, Cr), which remains to be confirmed.

The pyrazole-based Schiff base (E)-3-tert-butyl-N-[(2-nitrophenyl)methylidene]-1-phenyl-1H-pyrazol-5-amine, C₂₀H₂₀N₄O₂, was synthesized in a straightforward manner via a solventless maceration technique, and its structure elucidated through spectroscopic characterization and single-crystal X-ray diffraction analysis. The compound exhibits a degree of coplanarity, influenced by the ortho-nitro group on a phenyl ring. Crystal structure analysis, complemented by Hirshfeld surface analysis and QTAIM-C calculations, reveals that the crystal packing is mainly stabilized by a network of π-stacking and dispersion interactions. Notably, H...C π-stacking interactions, particularly those between ortho- and para-C-H atoms of phenyl groups, play a significant role in the packing motif. The Hirshfeld surface also reveals a 5.8% contribution from H...N contacts, involving aliphatic H atoms interacting with a pyrazole N atom. CE-B3LYP calculations highlight the dominance of dispersion forces in the crystal, with the strongest interaction energy calculated to be -58.9 kJ mol^-1 between the central molecule and the molecular pair related by the identity symmetry operation (x, y, z). These findings provide insights into the structure-property relationships of this compound and contribute to understanding crystal engineering principles for designing new materials.

As a new generation of multi-functional materials, crystalline coordination polymers have attracted widespread attention due to their fascinating framework structures, interesting topologies and potential applications. Two new coordination polymers, namely, poly[[μ₂-trans-1,2-bis(pyridin-3-yl)ethylene-κ²N:N']bis(μ₃-terephthalato-κ³O:O':O'')dizinc(II)], [Zn₂(C₈H₄O₄)₂(C₁₂H₁₀N₂)]_n or [Zn₂(tp)₂(3,3'-dpe)]_n, (I), and poly[diaqua[μ₂-trans-1,2-bis(pyridin-3-yl)-ethylene-κ²N:N']bis(μ₂-furan-2,5-dicarboxylate-κ²O:O')dizinc(II)], [Zn₂(C₆H₂O₅)₂(C₁₂H₁₀N₂)(H₂O)₂]_n or [Zn₂(fdc)₂(3,3'-dpe)(H₂O)₂]_n, (II), have been prepared by the hydrothermal reactions between Zn(NO₃)₂·6H₂O and trans-1,2-bis(pyridin-3-yl)ethylene (3,3'-dpe) with two similar dicarboxylic acids, i.e. terephthalic acid (H₂tp) and furan-2,5-dicarboxylic acid (H₂fdc), respectively. The coordination framework of (I) is a 3D pcu net with the point symbol 4¹²6³. The void space of the single framework in (I) is filled by the mutual interpenetration of two crystallographically equivalent networks, forming a threefold interpenetrating 3D architecture. Compound (II) is a 2D 3-connected coordination network parallel to the bc plane with the Schläfli symbol 6³. Neighbouring 2D coordination networks are further connected to each other via hydrogen-bonding interactions to produce a 3D supramolecular framework. The thermal stability and photoluminescence properties of these two coordination polymers have also been investigated.