structure Synthesis, crystal structure and Hirshfeld surface analysis of (2-amino-1-methylbenzimidazole-κN3)aquabis(4-oxopent-2-en-2-olato-κ2O,O')nickel(II) ethanol monosolvate By journals.iucr.org Published On :: 2024-10-22 The molecule of the title compound, [Ni(C5H7O2)2(C8H9N3)(H2O)]·C2H5OH, has triclinic (Poverline{1}) symmetry. This compound is of interest for its antimicrobial properties. The asymmetric unit comprises two independent complex molecules, which are linked by N—H⋯O and O—H⋯O hydrogen bonds along [111]. Hirshfeld surface analysis indicates that 71.7% of intermolecular interactions come from H⋯H contacts, 17.7% from C⋯H/H⋯C contacts and 7.6% from O⋯H/H⋯O contacts, with the remaining contribution coming from N⋯H/H⋯N, C⋯N/N⋯C, C⋯C and O⋯O contacts. Full Article text
structure Synthesis and crystal structure of poly[ethanol(μ-4-methylpyridine N-oxide)di-μ-thiocyanato-cobalt(II)] By journals.iucr.org Published On :: 2024-09-20 Reaction of 4-methylpyridine N-oxide and Co(NCS)2 in ethanol as solvent accidentally leads to the formation of single crystals of Co(NCS)2(4-methylpyridine N-oxide)(ethanol) or [Co(NCS)2(C6H7NO)(C2H6O)]n. The asymmetric unit of the title compound consists of one CoII cation, two crystallographically independent thiocyanate anions, one 4-methylpyridine N-oxide coligand and one ethanol molecule on general positions. The cobalt cations are sixfold coordinated by one terminal and two bridging thiocyanate anions, two bridging 4-methylpyridine N-oxide coligands and one ethanol molecule, with a slightly distorted octahedral geometry. The cobalt cations are linked by single μ-1,3(N,S)-bridging thiocyanate anions into corrugated chains, that are further connected into layers by pairs of μ-1,1(O,O)-bridging 4-methylpyridine N-oxide coligands. The layers are parallel to the bc plane and are separated by the methyl groups of the 4-methylpyridine N-oxide coligands. Within the layers, intralayer hydrogen bonding is observed. Full Article text
structure Crystal structures of seven mixed-valence gold compounds of the form [(R1R2R3PE)2AuI]+[AuIIIX4]− (R = tert-butyl or isopropyl, E = S or Se, and X = Cl or Br) By journals.iucr.org Published On :: 2024-09-30 During our studies of the oxidation of gold(I) complexes of trialkylphosphane chalcogenides, general formula R1R2R3PEAuX, (R = tert-butyl or isopropyl, E = S or Se, X = Cl or Br) with PhICl2 or elemental bromine, we have isolated a set of seven mixed-valence by-products, the bis(trialkylphosphane chalcogenido)gold(I) tetrahalogenidoaurates(III) [(R1R2R3PE)2Au]+[AuX4]−. These correspond to the addition of one halogen atom per gold atom of the AuI precursor. Compound 1, bis(triisopropylphosphane sulfide)gold(I) tetrachloridoaurate(III), [Au(C9H21PS)2][AuCl4] or [(iPr3PS)2Au][AuCl4], crystallizes in space group P21/n with Z = 4; the gold(I) atoms of the two cations lie on twofold rotation axes, and the gold(III) atoms of the two anions lie on inversion centres. Compound 2, bis(tert-butyldiisopropylphosphane sulfide)gold(I) tetrachloridoaurate(III), [Au(C10H23PS)2][AuCl4] or [(tBuiPr2PS)2Au][AuCl4], crystallizes in space group P1 with Z = 4; the asymmetric unit contains two cations and two anions with no imposed symmetry. A least-squares fit of the two cations gave an r.m.s. deviation of 0.19 Å. Compound 3, bis(tri-tert-butylphosphane sulfide)gold(I) tetrachloridoaurate(III), [Au(C12H27PS)2][AuCl4] or [(tBu3PS)2Au][AuCl4], crystallizes in space group P1 with Z = 1; both gold atoms lie on inversion centres. Compound 4a, bis(tert-butyldiisopropylphosphane sulfide)gold(I) tetrabromidoaurate(III), [Au(C10H23PS)2][AuBr4] or [(tBuiPr2PS)2Au][AuBr4], crystallizes in space group P21/c with Z = 4; the cation lies on a general position, whereas the gold(III) atoms of the two anions lie on inversion centres. Compound 4b, bis(tert-butyldiisopropylphosphane selenide)gold(I) tetrabromidoaurate(III), [Au(C10H23PSe)2][AuBr4] or [(tBuiPr2PSe)2Au][AuBr4], is isotypic with 4a. Compound 5a, bis(tri-tert-butylphosphane sulfide)gold(I) tetrabromidoaurate(III), [Au(C12H27PS)2][AuBr4] or [(tBu3PS)2Au][AuBr4], is isotypic with compound 4a. Compound 5a, bis(tri-tert-butylphosphane sulfide)gold(I) tetrabromidoaurate(III), [Au(C12H27PS)2][AuBr4] or [(tBu3PS)2Au][AuBr4], crystallizes in space group P1 with Z = 1; both gold atoms lie on inversion centres. Compound 5b, bis(tri-tert-butylphosphane selenide)gold(I) tetrabromidoaurate(III), [Au(C12H27PSe)2][AuBr4] or [(tBu3PSe)2Au][AuBr4], is isotypic with 5a. All AuI atoms are linearly coordinated and all AuIII atoms exhibit a square-planar coordination environment. The ligands at the AuI atoms are antiperiplanar to each other across the S⋯S vectors. There are several short intramolecular H⋯Au and H⋯E contacts. Average bond lengths (Å) are: P—S = 2.0322, P—Se = 2.1933, S—Au = 2.2915, and Se—Au = 2.4037. The complex three-dimensional packing of 1 involves two short C—Hmethine⋯Cl contacts (and some slightly longer contacts). For 2, four C—Hmethine⋯Cl interactions combine to produce zigzag chains of residues parallel to the c axis. Additionally, an S⋯Cl contact is observed that might qualify as a ‘chalcogen bond’. The packing of 3 is three-dimensional, but can be broken down into two layer structures, each involving an S⋯Cl and an H⋯Cl contact. For the bromido derivatives 4a/b and 5a/b, loose associations of the anions form part of the packing patterns. For all four compounds, these combine with an E⋯Br contact to form layers parallel to the ab plane. Full Article text
structure Synthesis, non-spherical structure refinement and Hirshfeld surface analysis of racemic 2,2'-diisobutoxy-1,1'-binaphthalene By journals.iucr.org Published On :: 2024-09-24 In the racemic title compound, C28H30O2, the naphthyl ring systems subtend a dihedral angle of 68.59 (1)° and the molecular conformation is consolidated by a pair of intramolecular C—H⋯π contacts. The crystal packing features a weak C—H⋯π contact and van der Waals forces. A Hirshfeld surface analysis of the crystal structure reveals that the most significant contributions are from H⋯H (73.2%) and C⋯H/H⋯C (21.2%) contacts. Full Article text
structure Crystal structure and Hirshfeld surface analysis of trichlorido(1,10-phenanthroline-κ2N,N')phenyltin(IV) By journals.iucr.org Published On :: 2024-09-24 The title compound, [Sn(C6H5)Cl3(C12H8N2)], which was obtained by the reaction between 1,10-phenanthroline and phenyltin trichloride in methanol, exhibits intramolecular hydrogen-bonding interactions involving the chlorine and hydrogen atoms. Crystal cohesion is ensured by intermolecular C—H⋯Cl hydrogen bonds, as well as Y—X⋯π and π-stacking interactions involving three different aromatic rings with centroid–centroid distances of 3.6605 (13), 3.9327 (14) and 3.6938 (12) Å]. Hirshfeld surface analysis and the associated two-dimensional fingerprint plots reveal significant contributions from H⋯H (30.7%), Cl⋯H/H⋯Cl (32.4%), and C⋯H/H⋯C (24.0%) contacts to the crystal packing while the C⋯C (6.2%), C⋯Cl/Cl⋯C (4.1%), and N⋯H/H⋯N (1.7%) interactions make smaller contributions. Full Article text
structure Crystal structure and Hirshfeld surface analysis of {2-[bis(pyridin-2-ylmethyl)amino]ethane-1-thiolato}chloridocadmium(II) By journals.iucr.org Published On :: 2024-09-30 The title compound, [Cd(C14H16N3S)Cl] or [CdLCl] (1), where LH = 2-[bis(pyridin-2-ylmethyl)amino]ethane-1-thiol, was prepared and structurally characterized. The Cd2+ complex crystallizes in P21/c with a distorted trigonal–bipyramidal metal coordination geometry. Supramolecular interactions in 1 include parallel offset face-to-face interactions between inversion-related pyridyl rings and potential hydrogen bonds with chlorine or sulfur as the acceptor. Additional cooperative pyridyl–pyridyl interactions with roughly 45° tilt angles and centroid–centroid distances of less than 5.5 Å likely also contribute to the overall solid-state stability. Hirshfeld surface analysis indicates that H⋯H (51.2%), Cl⋯H/H⋯Cl (13.9%), C⋯H/H⋯C (12.3%) and S⋯H/H⋯S (11.8%) interactions are dominant in the solid state. Full Article text
structure Synthesis and crystal structure of poly[[μ-chlorido-μ-(2,3-dimethylpyrazine)-copper(I)] ethanol hemisolvate], which shows a new isomeric CuCl(2,3-dimethylpyrazine) network By journals.iucr.org Published On :: 2024-09-24 Reaction of copper(I)chloride with 2,3-dimethylpyrazine in ethanol leads to the formation of the title compound, poly[[μ-chlorido-μ-(2,3-dimethylpyrazine)-copper(I)] ethanol hemisolvate], {[CuCl(C6H8N2)]·0.5C2H5OH}n or CuCl(2,3-dimethylpyrazine) ethanol hemisolvate. Its asymmetric unit consists of two crystallographically independent copper cations, two chloride anions and two 2,3-dimethylpyrazine ligands as well as one ethanol solvate molecule in general positions. The ethanol molecule is disordered and was refined using a split model. The methyl H atoms of the 2,3-dimethylpyrazine ligands are also disordered and were refined in two orientations rotated by 60° relative to each other. In the crystal structure, each copper cation is tetrahedrally coordinated by two N atoms of two bridging 2,3-dimethylpyrazine ligands and two μ-1,1-bridging chloride anions. Each of the two copper cations are linked by pairs of bridging chloride anions into dinuclear units that are further linked into layers via bridging 2,3-dimethylpyrazine coligands. These layers are stacked in such a way that channels are formed in which the disordered solvent molecules are located. The topology of this network is completely different from that observed in the two polymorphic modifications of CuCl(2,3-dimethylpyrazine) reported in the literature [Jess & Näther (2006). Inorg. Chem. 45, 7446–7454]. Powder X-ray diffraction measurements reveal that the title compound is unstable and transforms immediately into an unknown crystalline phase. Full Article text
structure Synthesis, crystal structure and Hirshfeld surface analysis of sulfamethoxazolium methylsulfate monohydrate By journals.iucr.org Published On :: 2024-09-24 The molecular salt sulfamethoxazolium {or 4-[(5-methyl-1,2-oxazol-3-yl)sulfamoyl]anilinium methyl sulfate monohydrate}, C10H12N3O3S+·CH3O4S−·H2O, was prepared by the reaction of sulfamethoxazole and H2SO4 in methanol and crystallized from methanol–ether–water. Protonation takes place at the nitrogen atom of the primary amino group. In the crystal, N—H⋯O hydrogen bonds (water and methylsulfate anion) and intermolecular N—H⋯N interactions involving the sulfonamide and isoxazole nitrogen atoms, link the components into a tri-dimensional network, additional cohesion being provided by face-to-face π–π interactions between the phenyl rings of adjacent molecules. A Hirshfeld surface analysis was used to verify the contributions of the different intermolecular interactions, showing that the three most important contributions for the crystal packing are from H⋯O (54.1%), H⋯H (29.2%) and H⋯N (5.0%) interactions. Full Article text
structure Crystal structure and Hirshfeld surface analyses, crystal voids, intermolecular interaction energies and energy frameworks of 3-benzyl-1-(3-bromopropyl)-5,5-diphenylimidazolidine-2,4-dione By journals.iucr.org Published On :: 2024-10-04 The title molecule, C25H23BrN2O2, adopts a cup shaped conformation with the distinctly ruffled imidazolidine ring as the base. In the crystal, weak C—H⋯O hydrogen bonds and C—H⋯π(ring) interactions form helical chains of molecules extending along the b-axis direction that are linked by additional weak C—H⋯π(ring) interactions across inversion centres. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (51.0%), C⋯H/H⋯C (21.3%), Br⋯H/H⋯Br (12.8%) and O⋯H/H⋯O (12.4%) interactions. The volume of the crystal voids and the percentage of free space were calculated to be 251.24 Å3 and 11.71%, respectively, showing that there is no large cavity in the crystal packing. Evaluation of the electrostatic, dispersion and total energy frameworks indicate that the stabilization is dominated by the dispersion energy. Full Article text
structure Crystal structure and supramolecular features of a host–guest inclusion complex based on A1/A2-hetero-difunctionalized pillar[5]arene By journals.iucr.org Published On :: 2024-09-24 A host–guest supramolecular inclusion complex was obtained from the co-crystallization of A1/A2-bromobutoxy-hydroxy difunctionalized pillar[5]arene (PilButBrOH) with adiponitrile (ADN), C47H53.18Br0.82O10·C6H8N2. The adiponitrile guest is stabilized within the electron-rich cavity of the pillar[5]arene host via multiple C—H⋯O and C—H⋯π interactions. Both functional groups on the macrocyclic rim are engaged in supramolecular interactions with an adjacent inclusion complex via hydrogen-bonding (O—H⋯N or C—H⋯Br) interactions, resulting in the formation of a supramolecular dimer in the crystal structure. Full Article text
structure Synthesis and crystal structure of 1H-1,2,4-triazole-3,5-diamine monohydrate By journals.iucr.org Published On :: 2024-10-11 The title compound, a hydrate of 3,5-diamino-1,2,4-triazole (DATA), C2H5N5·H2O, was synthesized in the presence of sodium perchlorate. The evaporation of H2O from its aqueous solution resulted in anhydrous DATA, suggesting that sodium perchlorate was required to precipitate the DATA hydrate. The DATA hydrate crystallizes in the P21/c space group in the form of needle-shaped crystals with one DATA and one water molecule in the asymmetric unit. The water molecules form a three-dimensional network in the crystal structure. Hirshfeld surface analysis revealed that 8.5% of the intermolecular interactions originate from H⋯O contacts derived from the incorporation of the water molecules. Full Article text
structure Synthesis, crystal structure and properties of μ-tetrathioantimonato-bis[(cyclam)zinc(II)] perchlorate 0.8-hydrate By journals.iucr.org Published On :: 2024-10-11 The reaction of Zn(ClO4)2·6H2O with Na3SbS4·9H2O in a water/acetonitrile mixture leads to the formation of the title compound, (μ-tetrathioantimonato-κ2S:S')bis[(1,4,8,11-tetraazacyclotetradecane-κ4N)zinc(II)] perchlorate 0.8-hydrate, [Zn2(SbS4)(C10H24N4)2]ClO4·0.8H2O or [(Zn-cyclam)2(SbS4)]+[ClO4]−·0.8H2O. The asymmetric unit consists of two crystallographically independent [SbS4]3– anions, two independent perchlorate anions and two independent water molecules as well as four crystallographically independent Zn(cyclam)2+ cations that are located in general positions. Both perchlorate anions and one cyclam ligand are disordered and were refined with a split mode using restraints. The water molecules are partially occupied. Two Zn(cyclam)2+ cations are linked via the [SbS4]3– anions into [Zn2(cyclam)2SbS4]+ cations that are charged-balanced by the [ClO4]− anions. The water molecules of crystallization are hydrogen bonded to the [SbS4]3– anions. The cations, anions and water molecules are linked by N—H⋯O, N—H⋯S and O—H⋯S hydrogen bonds into a three-dimensional network. Powder X-ray diffraction proves that a pure sample had been obtained that was additionally investigated for its spectroscopic properties. Full Article text
structure Structure of 2,3,5-triphenyltetrazol-3-ium chloride hemipentahydrate By journals.iucr.org Published On :: 2024-09-30 The title hydrated molecular salt, C19H15N4+·Cl−·2.5H2O, has two triphenyltetrazolium cations, two chloride anions and five water molecules in the asymmetric unit. The cations differ in the conformations of the phenyl rings with respect to the heterocyclic core, most notably for the C-bonded phenyl ring, for which the N—C—C—C torsion angles differ by 36.4 (3)°. This is likely a result of one cation accepting an O—H⋯N hydrogen bond from a water molecule [O⋯N = 3.1605 (15) Å], while the other cation accepts no hydrogen bonds. In the extended structure, the water molecules are involved in centrosymmetric (H2O)2Cl2 rings as well as (H2O)4 chains. An unusual O—H⋯π interaction and weak C—H⋯O and C—H⋯Cl hydrogen bonds are also observed. Full Article text
structure Crystal structure and Hirshfeld surface analysis of (nitrato-κ2O,O')(1,4,7,10-tetraazacyclododecane-κ4N)nickel(II) nitrate By journals.iucr.org Published On :: 2024-10-11 The crystal structure of the title compound, [Ni(C8H20N4)(NO3)]NO3, at room temperature, has monoclinic (P21/n) symmetry. The structure displays intermolecular hydrogen bonding. The nickel displays a distorted bipyramidal geometry with the symmetric bidentate bonded nitrate occupying an equatorial site. The 1,4,7,10-tetraazacyclododecane (cyclen) backbone has the [4,8] configuration, with three nitrogen-bound H atoms directed above the plane of the nitrogen atoms towards the offset nickel atom with the fourth nitrogen-bound hydrogen directed below from the plane of the nitrogen atoms. The nitrate anion O atoms are seen to hydrogen bond to the H atoms bound to the N atoms of the ligand. Full Article text
structure Synthesis, structures and Hirshfeld surface analyses of 2-hydroxy-N'-methylacetohydrazide and 2-hydroxy-N-methylacetohydrazide By journals.iucr.org Published On :: 2024-10-15 The structures of the title compounds 2-hydroxy-N'-methylacetohydrazide, 1, and 2-hydroxy-N-methylacetohydrazide, 2, both C3H8N2O2, as regioisomers differ in the position of the methyl group relative to the N atoms in 2-hydroxy-acetohydrazide. In the structure of 1, the 2-hydroxy-acetohydrazide core [OH—C—C(=O)—NH—NH] is almost planar and the methyl group is rotated relative to this plane. As opposed to 1, in the structure of 2 all non-hydrogen atoms lie in the same plane. The hydroxyl and carbonyl groups in structures 1 and 2 are in trans and cis positions, respectively. The methyl amino group and carbonyl group are in the cis position relative to the C—N bond in structure 1, while the amino group and carbonyl group are in the trans position relative to the C—N bond in stucture 2. In the crystal, molecules of 1 are linked by N—H⋯O and O—H⋯N intermolecular hydrogen bonds, forming layers parallel to the ab crystallographic plane. A Hirshfeld surface analysis showed that the H⋯H contacts dominate the crystal packing with a contribution of 55.3%. The contribution of the H⋯O/O⋯H interaction is somewhat smaller, amounting to 30.8%. In the crystal, as a result of the intermolecular O—H⋯O hydrogen bonds, molecules of 2 form dimers, which are linked by N—H⋯O hydrogen bonds and a three-dimensional supramolecular network The major contributors to the Hirshfeld surface are H⋯H (58.5%) and H⋯O/O⋯H contacts (31.7%). Full Article text
structure The crystal structures determination and Hirshfeld surface analysis of N-(4-bromo-3-methoxyphenyl)- and N-{[3-bromo-1-(phenylsulfonyl)-1H-indol-2-yl]methyl}- derivatives of N-{[3-bromo-1-(phenylsulfonyl)-1H-indol- By journals.iucr.org Published On :: 2024-10-04 Two new phenylsulfonylindole derivatives, namely, N-{[3-bromo-1-(phenylsulfonyl)-1H-indol-2-yl]methyl}-N-(4-bromo-3-methoxyphenyl)benzenesulfonamide, C28H22Br2N2O5S2, (I), and N,N-bis{[3-bromo-1-(phenylsulfonyl)-1H-indol-2-yl]methyl}benzenesulfonamide, C36H27Br2N3O6S3, (II), reveal the impact of intramolecular π–π interactions of the indole moieties as a factor not only governing the conformation of N,N-bis(1H-indol-2-yl)methyl)amines, but also significantly influencing the crystal patterns. For I, the crystal packing is dominated by C—H⋯π and π–π bonding, with a particular significance of mutual indole–indole interactions. In the case of II, the molecules adopt short intramolecular π–π interactions between two nearly parallel indole ring systems [with the centroids of their pyrrole rings separated by 3.267 (2) Å] accompanied by a set of forced Br⋯O contacts. This provides suppression of similar interactions between the molecules, while the importance of weak C—H⋯O hydrogen bonding to the packing naturally increases. Short contacts of the latter type [C⋯O = 3.389 (6) Å] assemble pairs of molecules into centrosymmetric dimers with a cyclic R22(13) ring motif. These findings are consistent with the results of a Hirshfeld surface analysis and together they suggest a tool for modulating the supramolecular behavior of phenylsulfonylated indoles. Full Article text
structure Synthesis and crystal structure of sodium (ethane-1,2-diyl)bis[(3-methoxypropyl)phosphinodithiolate] octahydrate By journals.iucr.org Published On :: 2024-10-08 The title compound, catena-poly[[triaquasodium]-di-μ-aqua-[triaquasodium]-μ-(ethane-1,2-diyl)bis[(3-methoxypropyl)phosphinodithiolato]], [Na2(C10H22O2P2S4)(H2O)8]n, crystallizes in the triclinic space group P1. The dianionic [CH3O(CH2)3P(=S)(S—)CH2CH2P(=S)(S—)(CH2)3OCH3]2− ligand fragments are joined by a dicationic [Na2(H2O)8]2+ cluster that includes the oxygen of the methoxypropyl unit of the ligand to form infinite chains. Full Article text
structure Crystal structure of a hydrogen-bonded 2:1 co-crystal of 4-nitrophenol and 4,4'-bipyridine By journals.iucr.org Published On :: 2024-10-08 In the title compound, C10H8N2·2C6H5NO3, 4-nitrophenol and 4,4'-bipyridine crystallized together in a 2:1 ratio in the space group P21/n. There is a hydrogen-bonding interaction between the nitrogen atoms on the 4,4'-bipyridine molecule and the hydrogen atom on the hydroxyl group on the 4-nitrophenol, resulting in trimolecular units. This structure is a polymorph of a previously reported structure [Nayak & Pedireddi (2016). Cryst. Growth Des. 16, 5966–5975], which differs mainly due to a twist in the 4,4'-bipyridine molecule. Full Article text
structure Synthesis, crystal structure and absolute configuration of (3aS,4R,5S,7aR)-7-(but-3-en-1-yn-1-yl)-2,2-dimethyl-3a,4,5,7a-tetrahydro-2H-1,3-benzodioxole-4,5-diol By journals.iucr.org Published On :: 2024-10-11 The absolute configuration of the title compound, C13H16O4, determined as 1S,2R,3S,4R based on the synthetic pathway, was confirmed by single-crystal X-ray diffraction. The molecule is a relevant intermediary for the synthesis of speciosins, epoxyquinoides or their analogues. The molecule contains fused five- and six-membered rings with two free hydroxyl groups and two protected as an isopropylidenedioxo ring. The packing is directed by hydrogen bonds that define double planes of molecules laying along the ab plane and van der Waals interactions between aliphatic chains that point outwards of the planes. Full Article text
structure Crystal structures of two different multi-component crystals consisting of 1-(3,4-dimethoxybenzyl)-6,7-dimethoxyisoquinoline and fumaric acid By journals.iucr.org Published On :: 2024-10-11 Two different multi-component crystals consisting of papaverine [1-(3,4-dimethoxybenzyl)-6,7-dimethoxyisoquinoline, C20H21NO4] and fumaric acid [C4H4O4] were obtained. Single-crystal X-ray structure analysis revealed that one, C20H21NO4·1.5C4H4O4 (I), is a salt co-crystal composed of salt-forming and non-salt-forming molecules, and the other, C20H21NO4·0.5C4H4O4 (II), is a salt–co-crystal intermediate (i.e., in an intermediate state between a salt and a co-crystal). In this study, one state (crystal structure at 100 K) within the salt–co-crystal continuum is defined as the ‘intermediate’. Full Article text
structure Crystal structure of (μ2-7-{[bis(pyridin-2-ylmethyl)amino-1κ3N,N',N'']methyl}-5-chloroquinolin-8-olato-2κN;1:2κ2O)trichlorido-1κCl,2κ2Cl-dizinc(II) By journals.iucr.org Published On :: 2024-10-15 The title compound, [Zn2(C22H18ClN4O)Cl3], is a dinuclear zinc(II) complex with three chlorido ligands and one pentadentate ligand containing quinolin-8-olato and bis(pyridin-2-ylmethyl)amine groups. One of the two ZnII atom adopts a tetrahedral geometry and coordinates two chlorido ligands with chelate coordination of the N and O atoms of the quinolin-8-olato group in the ligand. The other ZnII atom adopts a distorted trigonal–bipyramidal geometry, and coordinates one chlorido-O atom of the quinolin-8-olato group and three N atoms of the bis(pyridin-2-ylmethyl)amine unit. In the crystal, two molecules are associated through a pair of intermolecular C—H⋯Cl hydrogen bonds, forming a dimer with an R22(12) ring motif. Another intermolecular C—H⋯Cl hydrogen bond forms a spiral C(8) chain running parallel to the [010] direction. The dimers are linked by these two intermolecular C—H⋯Cl hydrogen bonds, generating a ribbon sheet structure in ac plane. Two other intermolecular C—H⋯Cl hydrogen bonds form a C(7) chain along the c-axis direction and another C(7) chain generated by a d-glide plane. The molecules are cross-linked through the four intermolecular C—H⋯Cl hydrogen bonds to form a three-dimensional network. Full Article text
structure Crystal structure of N,N',N''-tricyclopropylbenzene-1,3,5-tricarboxamide By journals.iucr.org Published On :: 2024-10-24 The title compound, C18H21N3O3, was prepared from 1,3,5-benzenetricarbonyl trichloride and cyclopropylamine. Its crystal structure was solved in the monoclinic space group P21/c. In the crystal, the three amide groups of the molecule are inclined at angles of 26.5 (1), 36.9 (1) and 37.8 (1)° with respect to the plane of the benzene ring. The molecules are linked by N—H⋯O hydrogen bonds, forming two-dimensional supramolecular aggregates that extend parallel to the crystallographic ab plane and are further connected by C—H⋯O contacts. As a result of the supramolecular interactions, a propeller-like conformation of the title molecule can be observed. Full Article text
structure Crystal structure of catena-poly[[diaquadiimidazolecobalt(II)]-μ2-2,3,5,6-tetrabromobenzene-1,4-dicarboxylato] By journals.iucr.org Published On :: 2024-10-31 The asymmetric unit of the title compound, [Co(C8Br4O4)(C3H4N2)2(H2O)2]n or [Co(Br4bdc)(im)2(H2O)2]n, comprises half of CoII ion, tetrabromobenzenedicarboxylate (Br4bdc2−), imidazole (im) and a water molecule. The CoII ion exhibits a six-coordinated octahedral geometry with two oxygen atoms of the Br4bdc2− ligand, two oxygen atoms of the water molecules, and two nitrogen atoms of the im ligands. The carboxylate group is nearly perpendicular to the benzene ring and shows monodentate coordination to the CoII ion. The CoII ions are bridged by the Br4bdc2− ligand, forming a one-dimensional chain. The carboxylate group acts as an intermolecular hydrogen-bond acceptor toward the im ligand and a coordinated water molecule. The chains are connected by interchain N—H⋯O(carboxylate) and O—H(water)⋯O(carboxylate) hydrogen-bonding interactions and are not arranged in parallel but cross each other via interchain hydrogen bonding and π–π interactions, yielding a three-dimensional network. Full Article text
structure Crystal structure, Hirshfeld surface analysis, and DFT and molecular docking studies of 6-cyanonaphthalen-2-yl 4-(benzyloxy)benzoate By journals.iucr.org Published On :: 2024-10-22 In the title compound, C25H17NO3, the torsion angle associated with the phenyl benzoate group is −173.7 (2)° and that for the benzyloxy group is −174.8 (2)° establishing an anti-type conformation. The dihedral angles between the ten-membered cyanonaphthalene ring and the aromatic ring of the phenyl benzoate and the benzyloxy fragments are 40.70 (10) and 87.51 (11)°, respectively, whereas the dihedral angle between the aromatic phenyl benzoate and the benzyloxy fragments is 72.30 (13)°. In the crystal, the molecules are linked by weak C—H⋯O interactions forming S(4) chains propagating parallel to [010]. The packing is consolidated by three C—H⋯π interactions and two π–π stacking interactions between the aromatic rings of naphthalene and phenyl benzoate with centroid-to-centroid distances of 3.9698 (15) and 3.8568 (15) Å, respectively. Intermolecular interactions were quantified using Hirshfeld surface analysis. The molecular structure was further optimized by density functional theory (DFT) at the B3LYP/6–311+ G(d,p) level, revealing that the energy gap between HOMO and LUMO is 3.17 eV. Molecular docking studies were carried out for the title compound as a ligand and SARS-Covid-2(PDB ID:7QF0) protein as a receptor giving a binding affinity of −9.5 kcal mol−1. Full Article text
structure Crystal structure of an acetonitrile solvate of 2-(3,4,5-triphenylphenyl)acetic acid By journals.iucr.org Published On :: 2024-10-24 Crystal growth of 2-(3,4,5-triphenylphenyl)acetic acid (1) from acetonitrile yields a monosolvate, C26H20O2·CH3CN, of the space group P1. In the crystal, the title molecule adopts a conformation in which the three phenyl rings are arranged in a paddlewheel-like fashion around the central arene ring and the carboxyl residue is oriented nearly perpendicular to the plane of this benzene ring. Inversion-symmetric dimers of O—H⋯O-bonded molecules of 1 represent the basic supramolecular entities of the crystal structure. These dimeric molecular units are further linked by C—H⋯O=C bonds to form one-dimensional supramolecular aggregates running along the crystallographic [111] direction. Weak Caryl—H⋯N interactions occur between the molecules of 1 and acetonitrile. Full Article text
structure Synthesis and crystal structure of 1,3,5-tris[(1H-benzotriazol-1-yl)methyl]-2,4,6-triethylbenzene By journals.iucr.org Published On :: 2024-10-31 In the crystal structure of the title compound, C33H33N9, the tripodal molecule exists in a conformation in which the substituents attached to the central arene ring are arranged in an alternating order above and below the ring plane. The three benzotriazolyl moieties are inclined at angles of 88.3 (1), 85.7 (1) and 82.1 (1)° with respect to the mean plane of the benzene ring. In the crystal, only weak molecular cross-linking involving C—H⋯N hydrogen bonds is observed. Full Article text
structure Crystal structure of [Ni(OH2)6]Cl2·(18-crown-6)2·2H2O By journals.iucr.org Published On :: 2024-10-24 The crystal structure of the title compound, hexaaquanickel(II) dichloride–1,4,7,10,13,16-hexaoxacyclooctadecane–water (1/2/2), [Ni(H2O)6]Cl2·2C12H24O6·2H2O, is reported. The asymmetric unit contains half of the Ni(OH2)6 moiety with a formula of C12H32ClNi0.50O10 at 105 K and triclinic (P1) symmetry. The [Ni(OH2)6]2+ cation has close to ideal octahedral geometry with O—Ni—O bond angles that are within 3° of idealized values. The supramolecular structure includes hydrogen bonding between the water ligands, 18-crown-6 molecules, Cl− anions, and co-crystallized water solvent. Two crown ether molecules flank the [Ni(OH2)6]2+ molecule at the axial positions in a sandwich-like structure. The relatively symmetric hydrogen-bonding network is enabled by small Cl− counter-ions and likely influences the more idealized octahedral geometry of [Ni(OH2)6]2+. Full Article text
structure Synthesis and structure of trans-2,5-dimethylpiperazine-1,4-diium dihydrogen diphosphate By journals.iucr.org Published On :: 2024-10-24 In the title salt, C6H16N22+ ·H2P2O72−, the complete dication is generated by a crystallographic centre of symmetry with the methyl groups in equatorial orientations. The complete dianion is generated by a crystallographic twofold axis with the central O atom lying on the axis: the P—O—P bond angle is 135.50 (12)°. In the crystal, the dihydrogen diphosphate anions are linked by O—H⋯O hydrogen bonds, generating (001) layers. The organic cations bond to the inorganic layers by way of N—H⋯O and C—H⋯O hydrogen bonds. A Hirshfeld surface analysis shows that the most important contributions for the crystal packing are from O⋯H/H⋯O (60.5%) and H⋯H (39.4%) contacts. Full Article text
structure Synthesis, crystal structure and Hirshfeld surface analysis of 2-{4-[(2-chlorophenyl)methyl]-3-methyl-6-oxopyridazin-1-yl}-N-phenylacetamide By journals.iucr.org Published On :: 2024-10-31 In the title molecule, C20H18ClN3O2, the 2-chlorophenyl group is disordered to a small extent [occupancies 0.875 (2)/0.125 (2)]. The phenylacetamide moiety is nearly planar due to a weak, intramolecular C—H⋯O hydrogen bond. In the crystal, N—H⋯O hydrogen bonds and π-stacking interactions between pyridazine and phenyl rings form helical chains of molecules in the b-axis direction, which are linked by C—H⋯O hydrogen bonds and C—H⋯π(ring) interactions. A Hirshfeld surface analysis was performed, which showed that H⋯H, C⋯H/H⋯C and O⋯H/H⋯O interactions to dominate the intermolecular contacts in the crystal. Full Article text
structure Crystal structures and photophysical properties of mono- and dinuclear ZnII complexes flanked by triethylammonium By journals.iucr.org Published On :: 2024-10-24 Two new zinc(II) complexes, triethylammonium dichlorido[2-(4-nitrophenyl)-4-phenylquinolin-8-olato]zinc(II), (C6H16N){Zn(C21H13N2O3)Cl2] (ZnOQ), and bis(triethylammonium) {2,2'-[1,4-phenylenebis(nitrilomethylidyne)]diphenolato}bis[dichloridozinc(II)], (C6H16N)2[Zn2(C20H14N2O2)Cl4] (ZnBS), were synthesized and their structures were determined using ESI–MS spectrometry, 1H NMR spectroscopy, and single-crystal X-ray diffraction. The results showed that the ligands 2-(4-nitrophenyl)-4-phenylquinolin-8-ol (HOQ) and N,N'-bis(2-hydroxybenzylidene)benzene-1,4-diamine (H2BS) were deprotonated by triethyl-amine, forming the counter-ion Et3NH+, which interacts via an N—H⋯O hydrogen bond with the ligand. The ZnII atoms have a distorted trigonal–pyramidal (ZnOQ) and distorted tetrahedral (ZnBS) geometries with a coordination number of four, coordinating with the ligands via N and O atoms. The N atoms coordinating with ZnII correspond to the heterocyclic nitrogen for the HOQ ligand, while for the H2BS ligand, it is the nitrogen of the imine (CH=N). The crystal packing of ZnOQ is characterized by C—H⋯π interactions, while that of ZnBS by C—H⋯Cl interactions. The emission spectra showed that ZnBS complex exhibits green fluorescence in the solid state with a small band-gap energy, and the ZnOQ complex does exhibit non-fluorescence. Full Article text
structure Crystal structure and Hirshfeld surface analysis of the salt 2-iodoethylammonium iodide – a possible side product upon synthesis of hybrid perovskites By journals.iucr.org Published On :: 2024-10-31 The title organic–inorganic hybrid salt, C2H7IN+·I−, is isotypic with its bromine analog, C2H7BrN+·Br− [Semenikhin et al. (2024). Acta Cryst. E80, 738–741]. Its asymmetric unit consists of one 2-iodoethylammonium cation and one iodide anion. The NH3+ group of the organic cation forms weak hydrogen bonds with four neighboring iodide anions, leading to the formation of supramolecular layers propagating parallel to the bc plane. Hirshfeld surface analysis reveals that the most important contribution to the crystal packing is from N—H⋯I interactions (63.8%). The crystal under investigation was twinned by a 180° rotation around [001]. Full Article text
structure Crystal structure of bis{5-(4-chlorophenyl)-3-[6-(1H-pyrazol-1-yl)pyridin-2-yl]-1H-1,2,4-triazol-1-ido}nickel(II) methanol disolvate By journals.iucr.org Published On :: 2024-10-31 The unit cell of the title compound, [Ni(C16H10ClN6)2]·2CH3OH, consists of a neutral complex and two methanol molecules. In the complex, the two tridentate 2-(3-(4-chlorophenyl)-1H-1,2,4-triazol-5-yl)-6-(1H-pyrazol-1-yl)pyridine ligands coordinate to the central NiII ion through the N atoms of the pyrazole, pyridine and triazole groups, forming a pseudooctahedral coordination sphere. Neighbouring tapered molecules are linked through weak C—H(pz)⋯π(ph) interactions into monoperiodic chains, which are further linked through weak C—H⋯N/C interactions into diperiodic layers. The intermolecular contacts were quantified using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H 32.8%, C⋯H/H⋯C 27.5%, N⋯H/H⋯N 15.1%, and Cl⋯H/H⋯Cl 14.0%. The average Ni—N bond distance is 2.095 Å. Energy framework analysis at the HF/3–21 G theory level was performed to quantify the interaction energies in the crystal structure. Full Article text
structure Crystal structure and Hirshfeld surface analysis of bis(benzoylacetonato)(ethanol)dioxidouranium(VI) By journals.iucr.org Published On :: 2024-11-05 A new uranium metal–organic complex salt, [U(C10H9O2)2O2(C2H6O)], with benzoyl acetone, namely, bis(benzoylacetonato)(ethanol)dioxidouranium(VI), was synthesized. The compound has monoclinic P21/n symmetry. The geometry of the seven-coordinate U atom is pentagonal bipyramidal, with the uranyl oxygen atoms in apical positions. In the complex, the ligands bind to the metal through oxygen atoms. Additional weak O—H⋯O contacts between the cations and anions consolidate the three-dimensional arrangement of the structure. On the Hirshfeld surface, the largest contributions come from the short contacts such as van der Waals forces, including H⋯H, O⋯H and C⋯H. Interactions including C⋯C and O⋯C contacts were also observed; however, their contribution to the overall cohesion of the crystal structure is minor. A packing analysis was performed to check the strength of the crystal packing. Full Article text
structure Synthesis and structure of pentakis(2-aminopyridinium) nonavanado(V)tellurate(VI) By journals.iucr.org Published On :: 2024-12-01 In the title compound, (C5H7N2)5[TeV9O28], the tellurium and vanadium atoms are statistically disordered over two of the ten metal-atom sites in the [TeV9O28]5– heteropolyanion. The anions stack along [100] and are extended into a three-dimensional supramolecular network through N—H⋯O and weak C—H⋯O hydrogen bonds involving the self-assembled 2-aminopyridinium pentamers, which are linked by C—H⋯π and π–π stacking interactions. The most important contributions to the Hirshfeld surface arise from O⋯H/H⋯O (54.8%), H⋯H (17.8%) and C⋯H/H⋯C (13.4%) contacts. Full Article text
structure Form factor of helical structures and twisted fibres By journals.iucr.org Published On :: 2023-11-07 A general formalism is presented for the isotropically averaged single-chain scattering function (form factor) of single, double, triple and higher-order helices, as well as twisted fibres consisting of concentric layers of strands. Form factors for double and triple helices with differently sized grooves have also been derived. The formulas include the longitudinal and transverse interference over the pitch and radius of the helices, respectively. The results may be useful for the analysis of small-angle scattering data of (bio)macromolecules or molecular assemblies exhibiting a helical arrangement. Full Article text
structure (U)SAXS characterization of porous microstructure of chert: insights into organic matter preservation By journals.iucr.org Published On :: 2023-11-15 This study characterizes the microstructure and mineralogy of 132 (ODP sample), 1000 and 1880 million-year-old chert samples. By using ultra-small-angle X-ray scattering (USAXS), wide-angle X-ray scattering and other techniques, the preservation of organic matter (OM) in these samples is studied. The scarce microstructural data reported on chert contrast with many studies addressing porosity evolution in other sedimentary rocks. The aim of this work is to solve the distribution of OM and silica in chert by characterizing samples before and after combustion to pinpoint the OM distribution inside the porous silica matrix. The samples are predominantly composed of alpha quartz and show increasing crystallite sizes up to 33 ± 5 nm (1σ standard deviation or SD). In older samples, low water abundances (∼0.03%) suggest progressive dehydration. (U)SAXS data reveal a porous matrix that evolves over geological time, including, from younger to older samples, (1) a decreasing pore volume down to 1%, (2) greater pore sizes hosting OM, (3) decreasing specific surface area values from younger (9.3 ± 0.1 m2 g−1) to older samples (0.63 ± 0.07 m2 g−1, 1σ SD) and (4) a lower background intensity correlated to decreasing hydrogen abundances. The pore-volume distributions (PVDs) show that pores ranging from 4 to 100 nm accumulate the greater volume fraction of OM. Raman data show aromatic organic clusters up to 20 nm in older samples. Raman and PVD data suggest that OM is located mostly in mesopores. Observed structural changes, silica–OM interactions and the hydrophobicity of the OM could explain the OM preservation in chert. Full Article text
structure POMFinder: identifying polyoxometallate cluster structures from pair distribution function data using explainable machine learning By journals.iucr.org Published On :: 2024-02-01 Characterization of a material structure with pair distribution function (PDF) analysis typically involves refining a structure model against an experimental data set, but finding or constructing a suitable atomic model for PDF modelling can be an extremely labour-intensive task, requiring carefully browsing through large numbers of possible models. Presented here is POMFinder, a machine learning (ML) classifier that rapidly screens a database of structures, here polyoxometallate (POM) clusters, to identify candidate structures for PDF data modelling. The approach is shown to identify suitable POMs from experimental data, including in situ data collected with fast acquisition times. This automated approach has significant potential for identifying suitable models for structure refinement to extract quantitative structural parameters in materials chemistry research. POMFinder is open source and user friendly, making it accessible to those without prior ML knowledge. It is also demonstrated that POMFinder offers a promising modelling framework for combined modelling of multiple scattering techniques. Full Article text
structure Fast nanoscale imaging of strain in a multi-segment heterostructured nanowire with 2D Bragg ptychography By journals.iucr.org Published On :: 2024-02-01 Developing semiconductor devices requires a fast and reliable source of strain information with high spatial resolution and strain sensitivity. This work investigates the strain in an axially heterostructured 180 nm-diameter GaInP nanowire with InP segments of varying lengths down to 9 nm, simultaneously probing both materials. Scanning X-ray diffraction (XRD) is compared with Bragg projection ptychography (BPP), a fast single-projection method. BPP offers a sufficient spatial resolution to reveal fine details within the largest segments, unlike scanning XRD. The spatial resolution affects the quantitative accuracy of the strain maps, where BPP shows much-improved agreement with an elastic 3D finite element model compared with scanning XRD. The sensitivity of BPP to small deviations from the Bragg condition is systematically investigated. The experimental confirmation of the model suggests that the large lattice mismatch of 1.52% is accommodated without defects. Full Article text
structure Refinement of X-ray and electron diffraction crystal structures using analytical Fourier transforms of Slater-type atomic wavefunctions in Olex2 By journals.iucr.org Published On :: 2024-02-01 An implementation of Slater-type spherical scattering factors for X-ray and electron diffraction for elements in the range Z = 1–103 is presented within the software Olex2. Both high- and low-angle Fourier behaviour of atomic electron density and electrostatic potential can thus be addressed, in contrast to the limited flexibility of the four Gaussian plus constant descriptions which are currently the most widely used method for calculating atomic scattering factors during refinement. The implementation presented here accommodates the increasing complexity of the electronic structure of heavier elements by using complete atomic wavefunctions without any interpolation between precalculated tables or intermediate fitting functions. Atomic wavefunctions for singly charged ions are implemented and made accessible, and these show drastic changes in electron diffraction scattering factors compared with the neutral atom. A comparison between the two different spherical models of neutral atoms is presented as an example for four different kinds of X-ray and two electron diffraction structures, and comparisons of refinement results using the existing diffraction data are discussed. A systematic but slight improvement in R values and residual densities can be observed when using the new scattering factors, and this is discussed relative to effects on the atomic displacement parameters and atomic positions, which are prominent near the heavier elements in a structure. Full Article text
structure A workflow for single-particle structure determination via iterative phasing of rotational invariants in fluctuation X-ray scattering By journals.iucr.org Published On :: 2024-03-15 Fluctuation X-ray scattering (FXS) offers a complementary approach for nano- and bioparticle imaging with an X-ray free-electron laser (XFEL), by extracting structural information from correlations in scattered XFEL pulses. Here a workflow is presented for single-particle structure determination using FXS. The workflow includes procedures for extracting the rotational invariants from FXS patterns, performing structure reconstructions via iterative phasing of the invariants, and aligning and averaging multiple reconstructions. The reconstruction pipeline is implemented in the open-source software xFrame and its functionality is demonstrated on several simulated structures. Full Article text
structure From solution to structure: empowering inclusive cryo-EM with a pre-characterization pipeline for biological samples By journals.iucr.org Published On :: 2024-03-26 In addressing the challenges faced by laboratories and universities with limited (or no) cryo-electron microscopy (cryo-EM) infrastructure, the ESRF, in collaboration with the Grenoble Institute for Structural Biology (IBS), has implemented the cryo-EM Solution-to-Structure (SOS) pipeline. This inclusive process, spanning grid preparation to high-resolution data collection, covers single-particle analysis and cryo-electron tomography (cryo-ET). Accessible through a rolling access route, proposals undergo scientific merit and technical feasibility evaluations. Stringent feasibility criteria demand robust evidence of sample homogeneity. Two distinct entry points are offered: users can either submit purified protein samples for comprehensive processing or initiate the pipeline with already vitrified cryo-EM grids. The SOS pipeline integrates negative stain imaging (exclusive to protein samples) as a first quality step, followed by cryo-EM grid preparation, grid screening and preliminary data collection for single-particle analysis, or only the first two steps for cryo-ET. In both cases, if the screening steps are successfully completed, high-resolution data collection will be carried out using a Titan Krios microscope equipped with a latest-generation direct electron counting detector coupled to an energy filter. The SOS pipeline thus emerges as a comprehensive and efficient solution, further democratizing access to cryo-EM research. Full Article text
structure SEB: a computational tool for symbolic derivation of the small-angle scattering from complex composite structures By journals.iucr.org Published On :: 2024-03-31 Analysis of small-angle scattering (SAS) data requires intensive modeling to infer and characterize the structures present in a sample. This iterative improvement of models is a time-consuming process. Presented here is Scattering Equation Builder (SEB), a C++ library that derives exact analytic expressions for the form factors of complex composite structures. The user writes a small program that specifies how the sub-units should be linked to form a composite structure and calls SEB to obtain an expression for the form factor. SEB supports e.g. Gaussian polymer chains and loops, thin rods and circles, solid spheres, spherical shells and cylinders, and many different options for how these can be linked together. The formalism behind SEB is presented and simple case studies are given, such as block copolymers with different types of linkage, as well as more complex examples, such as a random walk model of 100 linked sub-units, dendrimers, polymers and rods attached to the surfaces of geometric objects, and finally the scattering from a linear chain of five stars, where each star is built up of four diblock copolymers. These examples illustrate how SEB can be used to develop complex models and hence reduce the cost of analyzing SAS data. Full Article text
structure Synthesis and in-depth structure determination of a novel metastable high-pressure CrTe3 phase By journals.iucr.org Published On :: 2024-05-24 This study reports the synthesis and crystal structure determination of a novel CrTe3 phase using various experimental and theoretical methods. The average stoichiometry and local phase separation of this quenched high-pressure phase were characterized by ex situ synchrotron powder X-ray diffraction and total scattering. Several structural models were obtained using simulated annealing, but all suffered from an imperfect Rietveld refinement, especially at higher diffraction angles. Finally, a novel stoichiometrically correct crystal structure model was proposed on the basis of electron diffraction data and refined against powder diffraction data using the Rietveld method. Scanning electron microscopy–energy-dispersive X-ray spectrometry (EDX) measurements verified the targeted 1:3 (Cr:Te) average stoichiometry for the starting compound and for the quenched high-pressure phase within experimental errors. Scanning transmission electron microscopy (STEM)–EDX was used to examine minute variations of the Cr-to-Te ratio at the nanoscale. Precession electron diffraction (PED) experiments were applied for the nanoscale structure analysis of the quenched high-pressure phase. The proposed monoclinic model from PED experiments provided an improved fit to the X-ray patterns, especially after introducing atomic anisotropic displacement parameters and partial occupancy of Cr atoms. Atomic resolution STEM and simulations were conducted to identify variations in the Cr-atom site-occupancy factor. No significant variations were observed experimentally for several zone axes. The magnetic properties of the novel CrTe3 phase were investigated through temperature- and field-dependent magnetization measurements. In order to understand these properties, auxiliary theoretical investigations have been performed by first-principles electronic structure calculations and Monte Carlo simulations. The obtained results allow the observed magnetization behavior to be interpreted as the consequence of competition between the applied magnetic field and the Cr–Cr exchange interactions, leading to a decrease of the magnetization towards T = 0 K typical for antiferromagnetic systems, as well as a field-induced enhanced magnetization around the critical temperature due to the high magnetic susceptibility in this region. Full Article text
structure Quantitative selection of sample structures in small-angle scattering using Bayesian methods By journals.iucr.org Published On :: 2024-06-18 Small-angle scattering (SAS) is a key experimental technique for analyzing nanoscale structures in various materials. In SAS data analysis, selecting an appropriate mathematical model for the scattering intensity is critical, as it generates a hypothesis of the structure of the experimental sample. Traditional model selection methods either rely on qualitative approaches or are prone to overfitting. This paper introduces an analytical method that applies Bayesian model selection to SAS measurement data, enabling a quantitative evaluation of the validity of mathematical models. The performance of the method is assessed through numerical experiments using artificial data for multicomponent spherical materials, demonstrating that this proposed analysis approach yields highly accurate and interpretable results. The ability of the method to analyze a range of mixing ratios and particle size ratios for mixed components is also discussed, along with its precision in model evaluation by the degree of fitting. The proposed method effectively facilitates quantitative analysis of nanoscale sample structures in SAS, which has traditionally been challenging, and is expected to contribute significantly to advancements in a wide range of fields. Full Article text
structure Towards dynamically configured databases for CIFs: the new modulated structures open database at the Bilbao Crystallographic Server By journals.iucr.org Published On :: 2024-09-17 This article presents a web-based framework to build a database without in-depth programming knowledge given a set of CIF dictionaries and a collection of CIFs. The framework consists of two main elements: the public site that displays the information contained in the CIFs in an ordered manner, and the restricted administrative site which defines how that information is stored, processed and, eventually, displayed. Thus, the web application allows users to easily explore, filter and access the data, download the original CIFs, and visualize the structures via JSmol. The modulated structures open database B-IncStrDB, the official International Union of Crystallography repository for this type of material and available through the Bilbao Crystallographic Server, has been re-implemented following the proposed framework. Full Article text
structure Measurable structure factors of dense dispersions containing polydisperse optically inhomogeneous particles By journals.iucr.org Published On :: 2024-09-25 Here, it is investigated how optical properties of single scatterers in interacting multi-particle systems influence measurable structure factors. Both particles with linear gradients of their scattering length density and core–shell structures evoke characteristic deviations between the weighted sum 〈S(Q)〉 of partial structure factors in a multi-component system and experimentally accessible measurable structure factors SM(Q). While 〈S(Q)〉 contains only the structural information of self-organizing systems, SM(Q) is additionally influenced by the optical properties of their constituents, resulting in features such as changing amplitudes, additional peaks in the low-wavevector region or splitting of higher-order maxima, which are not related to structural reasons. It is shown that these effects can be systematically categorized according to the qualitative behaviour of the form factor in the Guinier region, which enables assessing the suitability of experimentally obtained structure factors to genuinely represent the microstructure of complex systems free from any particular model assumption. Hence, a careful data analysis regarding size distribution and optical properties of single scatterers is mandatory to avoid a misinterpretation of measurable structure factors. Full Article text
structure SUBGROUPS: a computer tool at the Bilbao Crystallographic Server for the study of pseudo-symmetric or distorted structures By journals.iucr.org Published On :: 2024-10-01 SUBGROUPS is a free online program at the Bilbao Crystallographic Server (https://www.cryst.ehu.es/). It permits the exploration of all possible symmetries resulting from the distortion of a higher-symmetry parent structure, provided that the relation between the lattices of the distorted and parent structures is known. The program calculates all the subgroups of the parent space group which comply with this relation. The required minimal input is the space-group information of the parent structure and the relation of the unit cell of the distorted or pseudo-symmetric structure with that of the parent structure. Alternatively, the wavevector(s) observed in the diffraction data characterizing the distortion can be introduced. Additional conditions can be added, including filters related to space-group representations. The program provides very detailed information on all the subgroups, including group–subgroup hierarchy graphs. If a Crystallographic Information Framework (CIF) file of the parent high-symmetry structure is uploaded, the program generates CIF files of the parent structure described under each of the chosen lower symmetries. These CIF files may then be used as starting points for the refinement of the distorted structure under these possible symmetries. They can also be used for density functional theory calculations or for any other type of analysis. The power and efficiency of the program are illustrated with a few examples. Full Article text
structure Maximize Your IT Infrastructure; Maximize Business Productivity By www.itsecurity.com Published On :: Fri, 26 Mar 2010 23:29:07 +0000 On-Demand Webinar >Watch Now!>>SPONSORED BY: Qwest Business Solutions®Watch this FREE on-demand 30-minute webcast to hear Qwest Communications CIO, Girish Varma, Qwest’s Director of... Full Article
structure Boost Performance & Efficiency with Your Data Center Infrastructure By www.itsecurity.com Published On :: Wed, 07 Jul 2010 19:54:12 +0000 On-Demand Webinar > Watch Now!>>SPONSORED BY: Juniper NetworksWatch this FREE on-demand webinar to learn how you and your company can get started down the road to reach the pinnacle ... Full Article
structure Overhaul of Government Public Health Infrastructure, New Partners Needed to Address Nations Health Challenges By Published On :: Mon, 11 Nov 2002 06:00:00 GMT As the recent spread of West Nile virus and the anthrax scare of 2001 dramatically illustrate, America faces a variety of new health challenges in the 21st century, along with a number of persistent problems, such as racial disparities in health status and care delivery. Full Article