Acta Crystallographica Section C Structural Chemistry最新文献

The rhodanine derivatives are a group of compounds known for their pharmacological action. Four new crystal structures of 3-[5-(chlorobenzylidene)rhodanine]propionic acid isomers, characterized by X-ray diffraction analysis and theoretical calculations, are reported. 3-[5-(2-Chlorobenzylidene)-4-oxo-2-sulfanylidene-1,3-thiazoliden-3-yl]propanoic acid, C₁₃H₁₀ClNO₃S₂, 1, crystallizes in the space group P2₁/c, with one molecule in the asymmetric unit. The other compounds, namely, 3-[5-(3-chlorobenzylidene)-4-oxo-2-sulfanylidene-1,3-thiazoliden-3-yl]propanoic acid, C₁₃H₁₀ClNO₃S₂, 2 and its polymorph 2p, and 3-[5-(4-chlorobenzylidene)-4-oxo-2-sulfanylidene-1,3-thiazoliden-3-yl]propanoic acid, C₁₃H₁₀ClNO₃S₂, 3, crystallize in the triclinic centrosymmetric space group, with one molecule in the asymmetric unit. The geometry of the created polymorphs indicates differences in the conformation of the carboxyethyl moiety and the position of the chlorine substituent on the aromatic ring. The crystal packing in all four presented crystal structures is dominated by intermolecular O-H...O hydrogen bonds. The calculated energies of the presented compounds show that the most biologically active, i.e. 1, has the lowest stability, while the least active, i.e. 3, is the most stable. Several theoretical descriptors were used to correlate the structural features of the studied compounds with their biological activity.

Centimeter-sized crystals of a new rubidium methanesulfonic acid salt, (methanesulfonato-κO)(methanesulfonic acid-κO)rubidium(I), [Rb(CH₃SO₃)(CH₃SO₃H)], have been prepared via precipitation from methanesulfonic acid and water under vacuum. The salt crystallizes in the monoclinic space group C2/c (No. 15). The structure is comprised of one-dimensional (1D) chains of alternating edge- and corner-sharing dirubidium cuboctahedra bridged by antiparallel methanesulfonate groups. The 1D chains are tightly packed via hydrogen bonding to adjacent chains with the two methanesulfonate units sharing a single H atom equally between them. The low-dimensional structure has a large optical bandgap of 5.4 eV with an absorption edge of 210 nm.

The structural and emission properties of two ruthenium(II) polypyridyl complexes, namely, carbonyl(4,4'-di-tert-butyl-2,2'-bypyridine)hydridobis(triphenylphosphine)ruthenium(II) hexafluorophosphate, [RuH(C₁₈H₂₄N₂)(C₁₈H₁₅P)₂(CO)]PF₆ or [Ru(H)(CO)(dtbbpy)(PPh₃)₂]PF₆ (dtbbpy is 4,4'-di-tert-butyl-2,2'-bipyridine), and (2,2'-biquinoline)carbonylhydridobis(triphenylphosphine)ruthenium(II) hexafluorophosphate, [RuH(C₁₈H₁₂N₂)(C₁₈H₁₅P)₂(CO)]PF₆ or [Ru(H)(CO)(bq)(PPh₃)₂]PF₆ (bq is 2,2'-biquinoline), were characterized by spectroscopic analysis, X-ray diffraction and density functional theory (DFT) computational methods, and compared to the parent [Ru(H)(CO)(bpy)(PPh₃)₂]PF₆ complex (bpy is 2,2'-bipyridine). The X-ray analysis of these compounds showed a slightly distorted octahedral geometry of the Ru^II ion typical for this kind of complex. Classical hydrogen bonds are not observed in the crystals of the investigated complexes. Weak intermolecular C-H...F contacts and, as shown by the Hirshfeld surface analysis, H...H interactions have the dominant contributions in the molecular packing in both structures. In CH₂Cl₂ solution at 298 K, both complexes show a weak broad emission band attributed to S₀←^3*MLCT transitions. At 77 K in frozen methanol/ethanol glass, the complexes exhibit strong luminescence of MLCT origin. DFT calculations confirm that the optimized geometries are in good agreement with the experimental structures. In the excited state, changes are observed in the metal-ligand bond lengths, which are consistent with a metal-to-ligand charge transfer (MLCT) character.

An overview of the development of electron diffraction and an introduction to the special issue Advances in Electron Diffraction for Structural Determination.

As the electron diffraction technique MicroED gains momentum and is increasingly embraced by researchers in both academia and industry, we have the opportunity to familiarize ourselves with the characteristics of MicroED data and results. The number of refined structures and their associated data is steadily growing and becoming more accessible to the scientific community, offering valuable insights into the significance and quality of MicroED-derived structures. Additionally, the growing body of experience is helping to identify best practices for the technique. In this summary, we highlight key lessons learned from these data and propose gold standards for the community to consider adopting.

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.