met Crystal structure of {4-[10,15,20-tris(4-methoxyphenyl)porphyrin-5-yl]benzyl 2-diazoacetato}zinc(II) By scripts.iucr.org Published On :: 2020-01-31 In the title compound, [Zn(C50H36N6O5)], the ZnII cation is chelated by four pyrrole N atoms of the porphyrinate anion and coordinated by a symmetry-generated keto O atom of the diazoester group in a distorted square-pyramidal geometry. The mean Zn—N(pyrrole) bond length is 2.058 Å and the Zn—O(diazoester) bond length is 2.179 (4) Å. The zinc cation is displaced by 0.2202 (13) Å from the N4C20 mean plane of the porphyrinate anion toward the O atom; the involvement of this atom leads to a [100] polymeric chain in the crystal. Full Article text
met Crystal structure, synthesis and thermal properties of bis(4-benzoylpyridine-κN)bis(isothiocyanato-κN)bis(methanol-κN)iron(II) By scripts.iucr.org Published On :: 2020-01-31 In the crystal structure of the title compound, [Fe(NCS)2(C12H9NO)2(CH4O)2], the FeII cations are octahedrally coordinated by two N atoms of 4-benzoylpyridine ligands, two N atoms of two terminal isothiocyanate anions and two methanol molecules into discrete complexes that are located on centres of inversion. These complexes are linked via intermolecular O—H⋯O hydrogen bonds between the methanol O—H H atoms and the carbonyl O atoms of the 4-benzoylpyridine ligands, forming layers parallel to (101). Powder X-ray diffraction proved that a pure sample was obtained but that this compound is unstable and transforms into an unknown crystalline phase within several weeks. However, the solvent molecules can be removed by heating in a thermobalance, which for the aged sample as well as the title compound leads to the formation of a compound with the composition Fe(NCS)2(4-benzoylpyridine)2, which exhibits a powder pattern that is similar to that of Mn(NCS)2(4-benzoylpyridine)2. Full Article text
met Crystal structure of 1,4,8,11-tetramethyl-1,4,8,11-tetraazoniacyclotetradecane bis(perchlorate) dichloride from synchrotron X-ray data By scripts.iucr.org Published On :: 2020-02-11 The crystal structure of title salt, C14H36N44+·2ClO4−·2Cl−, has been determined using synchrotron radiation at 220 K. The structure determination reveals that protonation has occurred at all four amine N atoms. The asymmetric unit contains one half-cation (completed by crystallographic inversion symmetry), one perchlorate anion and one chloride anion. A distortion of the perchlorate anion is due to its involvement in hydrogen-bonding interactions with the cations. The crystal structure is consolidated by intermolecular hydrogen bonds involving the 1,4,8,11-tetramethyl-1,4,8,11-tetraazoniacyclotetradecane N—H and C—H groups as donor groups, and the O atoms of the perchlorate and chloride anion as acceptor groups, giving rise to a three-dimensional network. Full Article text
met Crystal structure and Hirshfeld surface analysis of the methanol solvate of sclareol, a labdane-type diterpenoid By scripts.iucr.org Published On :: 2020-02-06 The title compound, C20H36O2·CH3OH [systematic name: (3S)-4-[(S)-3-hydroxy-3-methylpent-4-en-1-yl]-3,4a,8,8-tetramethyldecahydronaphthalen-3-ol methanol monosolvate], is a methanol solvate of sclareol, a diterpene oil isolated from the medicinally important medicinal herb Salvia sclarea, commonly known as clary sage. It crystallizes in space group P1 (No. 1) with Z' = 2. The sclareol molecule comprises two trans-fused cyclohexane rings, each having an equatorially oriented hydroxyl group, and a 3-methylpent-1-en-3-ol side chain. In the crystal, Os—H⋯Os, Os—H⋯Om, Om—H⋯Os and Om—H⋯Om (s = sclareol, m = methanol) hydrogen bonds connect neighboring molecules into infinite [010] chains. The title compound exhibits weak anti-leishmanial activity (IC50 = 66.4 ± 1.0 µM ml−1) against standard miltefosine (IC50 = 25.8 ± 0.2 µM ml−1). Full Article text
met The crystal structures and Hirshfeld surface analyses of a cadmium(II) and a zinc(II) mononuclear complex of the new tetrakis-substituted pyrazine ligand N,N',N'',N'''-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis By scripts.iucr.org Published On :: 2020-02-18 The whole molecule of the cadmium(II) complex, diiodido{N,N',N'',N'''-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline)-κ3N2,N1,N6}cadmium(II), [CdI2(C36H40N6)], (I), of the ligand N,N',N'',N'''-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline) (L), is generated by a twofold rotation symmetry; the twofold axis bisects the cadmium atom and the nitrogen atoms of the pyrazine ring. The ligand coordinates in a mono-tridentate manner and the cadmium atom has a fivefold CdN3I2 coordination environment with a distorted shape. In the zinc(II) complex, dichlorido{N,N',N'',N'''-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline)-κ3N2,N1,N6}zinc(II) dichloromethane 0.6-solvate, [ZnCl2(C36H40N6)]·0.6CH2Cl2, (II), ligand L also coordinates in a mono-tridentate manner and the zinc atom has a fivefold ZnN3Cl2 coordination environment with a distorted shape. It crystallized as a partial dichloromethane solvate. In the crystal of I, the complex molecules are linked by weak C—H⋯I contacts, forming ribbons propagating along [100]. In the crystal of II, the complex molecules are linked by a series of C—H⋯π interactions, forming layers lying parallel to the (1overline{1}1) plane. In the crystals of both compounds there are metal–halide⋯π(pyrazine) contacts present. The Hirshfeld analyses confirm the importance of the C—H⋯halide contacts in the crystal packing of both compounds. Full Article text
met Crystal structure, Hirshfeld surface analysis and DFT studies of 1,3-bis[2-methoxy-4-(prop-2-en-1-yl)phenoxy]propane By scripts.iucr.org Published On :: 2020-02-14 The asymmetric unit of the title compound, C23H28O4, comprises two half-molecules, with the other half of each molecule being completed by the application of twofold rotation symmetry. The two completed molecules both have a V-shaped appearance but differ in their conformations. In the crystal, each independent molecule forms chains extending parallel to the b axis with its symmetry-related counterparts through C—H⋯π(ring) interactions. Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (65.4%), H⋯C/C⋯H (21.8%) and H⋯O/O⋯H (12.3%) interactions. Optimized structures using density functional theory (DFT) at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined molecular structures in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap. Full Article text
met Phosphorescent mono- and diiridium(III) complexes cyclometalated by fluorenyl- or phenyl-pyridino ligands with bulky substituents, as prospective OLED dopants By scripts.iucr.org Published On :: 2020-02-18 The crystal structures of tris[9,9-dihexyl-2-(5-methoxypyridin-2-yl-κN)-9H-fluoren-3-yl-κC3]iridium pentane monosolvate, [Ir(C31H38NO)3]·C5H12, (I), di-μ2-chlorido-bis{bis[2-(5-fluoropyridin-2-yl)-9,9-dihexyl-9H-fluoren-3-yl]iridium} pentane 0.3-solvate, [Ir2(C30H35FN)4Cl2]·0.3C5H12, (II), di-μ2-cyanato-bis{bis[9,9-dihexyl-2-(5-methoxypyridin-2-yl)-9H-fluoren-1-yl]iridium} pentane monosolvate, [Ir2(C31H38NO)4(NCO)2(NCO)2]·C5H12, (III), and {μ-N,N'-bis[3,5-bis(trifluoromethyl)phenyl]oxamidato}bis(bis{2-[4-(2,4,6-trimethylphenyl)pyridin-2-yl]phenyl-κ2C1,N'}iridium)–chlorobenzene–pentane (1/2.3/0.4), [Ir2(C20H19N)4(C18H6F12N2O2)]·2.3C6H5Cl·0.4C5H12, (IV), synthesized in the quest for organic light-emitting devices, were determined. The bis-μ2-chloro and bis-μ2-cyanato complexes have ΔΔ and ΛΛ configurations of the distorted octahedral Ir centres in racemic crystals, whereas the oxamido complex has a centrosymmetric (meso) structure with the ΔΛ configuration. The bridging oxamido moiety has a nearly planar anti geometry. All structures show substantial disorder of both host molecules and solvents of crystallization. Full Article text
met Crystal structure of (4-chlorophenyl)(4-methylpiperidin-1-yl)methanone By scripts.iucr.org Published On :: 2020-03-13 The title compound, C13H16ClNO, contains a methylpiperidine ring in the stable chair conformation. The mean plane of the twisted piperidine ring subtends a dihedral angle of 39.89 (7)° with that of the benzene ring. In the crystal, weak C—H⋯O interactions link the molecules along the a-axis direction to form infinite molecular chains. H⋯H interatomic interactions, C—H⋯O intermolecular interactions and weak dispersive forces stabilize molecular packing and form a supramolecular network, as established by Hirshfeld surface analysis. Full Article text
met Crystal structure, characterization and Hirshfeld analysis of bis{(E)-1-[(2,4,6-tribromophenyl)diazenyl]naphthalen-2-olato}copper(II) dimethyl sulfoxide monosolvate By scripts.iucr.org Published On :: 2020-02-18 In the title compound, [Cu(C16H8Br3N2O)2]·C2H6OS, the CuII atom is tetracoordinated in a square-planar coordination, being surrounded by two N atoms and two O atoms from two N,O-bidentate (E)-1-[(2,4,6-tribromophenyl)diazenyl]naphthalen-2-olate ligands. The two N atoms and two O atoms around the metal center are trans to each other, with an O—Cu—O bond angle of 177.90 (16)° and a N—Cu—N bond angle of 177.8 (2)°. The average distances between the CuII atom and the coordinated O and N atoms are 1.892 (4) and 1.976 (4) Å, respectively. In the crystal, complexes are linked by C—H⋯O hydrogen bonds and by π–π interactions involving adjacent naphthalene ring systems [centroid–centroid distance = 3.679 (4) Å]. The disordered DMSO molecules interact weakly with the complex molecules, being positioned in the voids left by the packing arrangement of the square-planar complexes. The DMSO solvent molecule is disordered over two positions with occupancies of 0.70 and 0.30. Full Article text
met Crystal structure of a two-dimensional metal–organic framework assembled from lithium(I) and γ-cyclodextrin By scripts.iucr.org Published On :: 2020-02-14 The crystal structure of the polymeric title compound, catena-poly[[[diaqualithium]-μ-γ-cyclodextrin(1−)-[aqualithium]-μ-γ-cyclodextrin(1−)] pentadecahydrate], {[Li2(C48H79O40)2(H2O)3]·15H2O}n, consists of deprotonated γ-cyclodextrin (CD) molecules assembled by lithium ions into metal–organic ribbons that are cross-linked by multiple O—H⋯O hydrogen bonds into sheets extending parallel to (0overline11). Within a ribbon, one Li+ ion is coordinated by one deprotonated hydroxyl group of the first γ-CD torus and by one hydroxyl group of the second γ-CD torus as well as by two water molecules. The other Li+ ion is coordinated by one deprotonated hydroxyl and by one hydroxyl group of the second γ-CD torus, by one hydroxyl group of the first γ-CD torus as well as by one water molecule. The coordination spheres of both Li+ cations are distorted tetrahedral. The packing of the structure constitute channels along the a axis. Parts of the hydroxymethyl groups in cyclodextrin molecules as well as water molecules show two-component disorder. Electron density associated with additional disordered solvent molecules inside the cavities was removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9–18] routine in PLATON. These solvent molecules are not considered in the given chemical formula and other crystal data. Five out of the sixteen hydroxymethyl groups and one water molecule are disordered over two sets of sites. Full Article text
met Crystal structure of (R)-5-[(R)-3-(4-chlorophenyl)-5-methyl-4,5-dihydroisoxazol-5-yl]-2-methylcyclohex-2-enone By scripts.iucr.org Published On :: 2020-02-18 The title compound, C17H18ClNO2, was prepared and isolated as a pure diastereoisomer, using column chromatography followed by a succession of fractional crystallizations. Its exact structure was fully identified via 1H NMR and confirmed by X-ray diffraction. It is built up from a central five-membered dihydroisoxazole ring to which a p-chlorophenyl group and a cyclohex-2-enone ring are attached in the 3 and 5 positions. The cyclohex-2-one and isoxazoline rings each exhibit an envelope conformation. The crystal packing features C—H⋯O, C—H⋯N and C—H⋯π interactions, which generate a three-dimensional network. Full Article text
met Crystal structure of 1-[(4-methylbenzene)sulfonyl]pyrrolidine By scripts.iucr.org Published On :: 2020-02-28 The molecular structure of the title compound, C11H15NO2S, features a sulfonamide group with S=O bond lengths of 1.4357 (16) and 1.4349 (16) Å, an S—N bond length of 1.625 (2) Å, and an S—C bond length of 1.770 (2) Å. When viewing the molecule down the S—N bond, both N—C bonds of the pyrrolidine ring are oriented gauche to the S—C bond with torsion angles of −65.6 (2)° and 76.2 (2)°. The crystal structure features both intra- and intermolecular C—H⋯O hydrogen bonds, as well as intermolecular C—H⋯π and π–π interactions, leading to the formation of sheets parallel to the ac plane. Full Article text
met Crystal structure of 2-[bis(benzylsulfanyl)methyl]-6-methoxyphenol By scripts.iucr.org Published On :: 2020-03-03 The title compound, C22H22O2S2, 1, represents an example of an ortho-vanillin-based functionalized dithioether, which could be useful as a potential chelating ligand or bridging ligand for coordination chemistry. This dithioacetal 1 crystallizes in the orthorhombic space group Pbca. The phenyl rings of the benzyl groups and that of the vanillin unit form dihedral angles of 35.38 (6) and 79.77 (6)°, respectively. The crystal structure, recorded at 100 K, displays both weak intramolecular O—H⋯O and intermolecular O—H⋯S hydrogen bonding. Full Article text
met Syntheses and crystal structures of the one-dimensional coordination polymers formed by [Ni(cyclam)]2+ cations and 1,3-bis(3-carboxypropyl)tetramethyldisiloxane anions in different degrees of deprotonation By scripts.iucr.org Published On :: 2020-02-25 The asymmetric units of the title compounds, namely, catena-poly[[(1,4,8,11-tetraazacyclotetradecane-κ4N1,N4,N8,N11)nickel(II)]-μ-1,3-bis(3-carboxylatopropyl)tetramethyldisiloxane-κ2O:O'], [Ni(C10H24O5Si2)(C12H24N4)]n (I), and catena-poly[[[(1,4,8,11-tetraazacyclotetradecane-κ4N1,N4,N8,N11)nickel(II)]-μ-4-({[(3-carboxypropyl)dimethylsilyl]oxy}dimethylsilyl)butanoato-κ2O:O'] perchlorate], {[Ni(C10H25O5Si2)(C12H24N4)]ClO4}n (II), consist of one (in I) or two crystallographically non-equivalent (in II) centrosymmetric macrocyclic cations and one centrosymmetric dianion (in I) or two centrosymmetric monoanions (in II). In each compound, the metal ion is coordinated by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable trans-III conformation, and the mutually trans O atoms of the carboxylate in a slightly tetragonally distorted trans-NiN4O2 octahedral coordination geometry. The crystals of both types of compounds are composed of parallel polymeric chains of the macrocyclic cations linked by the anions of the acid running along the [101] and [110] directions in I and II, respectively. In I, each polymeric chain is linked to four neighbouring ones by hydrogen bonding between the NH groups of the macrocycle and the carboxylate O atoms, thus forming a three-dimensional supramolecular network. In II, each polymeric chain contacts with only two neighbours, forming hydrogen bonds between the partially protonated carboxylic groups of the bridging ligand. As a result, a lamellar structure is formed with the layers oriented parallel to the (1overline{1}1) plane. Full Article text
met Crystal structure analysis of ethyl 3-(4-chlorophenyl)-1,6-dimethyl-4-methylsulfanyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate By scripts.iucr.org Published On :: 2020-02-25 In the title compound, C18H18ClN3O2S, the dihedral angle between the fused pyrazole and pyridine rings is 3.81 (9)°. The benzene ring forms dihedral angles of 35.08 (10) and 36.26 (9)° with the pyrazole and pyridine rings, respectively. In the crystal, weak C—H⋯O hydrogen bonds connect molecules along [100]. Full Article text
met Unexpected formation of a co-crystal containing the chalcone (E)-1-(5-chlorothiophen-2-yl)-3-(3-methylthiophen-2-yl)prop-2-en-1-one and the keto–enol tautomer (Z)-1-(5-chlorothiophen-2-yl)-3-(3-methylthiophe By scripts.iucr.org Published On :: 2020-03-03 The title crystal structure is assembled from the superposition of two molecular structures, (E)-1-(5-chlorothiophen-2-yl)-3-(3-methylthiophen-2-yl)prop-2-en-1-one, C12H9ClOS2 (93%), and (Z)-1-(5-chlorothiophen-2-yl)-3-(3-methylthiophen-2-yl)prop-1-en-1-ol, C12H11ClOS2 (7%), 0.93C12H9ClOS2·0.07C12H11ClOS2. Both were obtained from the reaction of 3-methylthiophene-2-carbaldehyde and 1-(5-chlorothiophen-2-yl)ethanone. In the extended structure of the major chalcone component, molecules are linked by a combination of C—H⋯O/S, Cl⋯Cl, Cl⋯π and π–π interactions, leading to a compact three-dimensional supramolecular assembly. Full Article text
met Crystal structure and Hirshfeld surface analysis of 4-allyl-2-methoxy-6-nitrophenol By scripts.iucr.org Published On :: 2020-02-28 The asymmetric unit of the title compound, C10H11NO4, which was synthesized via nitration reaction of eugenol (4-allyl-2-methoxyphenol) with a mixture of nitric acid and sulfuric acid, consists of three independent molecules of similar geometry. Each molecule displays an intramolecular hydrogen bond involving the hydroxide and the nitro group forming an S(6) motif. The crystal cohesion is ensured by intermolecular C—H⋯O hydrogen bonds in addition to π–π stacking interactions between the aromatic rings [centroid–centroid distances = 3.6583 (17)–4.0624 (16) Å]. The Hirshfeld surface analysis and the two-dimensional fingerprint plots show that H⋯H (39.6%), O⋯H/H⋯O (37.7%), C⋯H/H⋯C (12.5%) and C⋯C (4%) are the most important contributors towards the crystal packing. Full Article text
met Crystal structures of the recreational drug N-(4-methoxyphenyl)piperazine (MeOPP) and three of its salts By scripts.iucr.org Published On :: 2020-03-05 Crystal structures are reported for N-(4-methoxyphenyl)piperazine (MeOPP), (I), and for its 3,5-dinitrobenzoate, 2,4,6-trinitrophenolate (picrate) and 4-aminobenzoate salts, (II)–(IV), the last of which crystallizes as a monohydrate. In MeOPP, C11H16N2O, (I), the 4-methoxyphenyl group is nearly planar and it occupies an equatorial site on the piperazine ring: the molecules are linked into simple C(10) chains by N—H⋯O hydrogen bonds. In each of the salts, i.e., C11H17N2O+·C7H3N2O6−, (II), C11H17N2O+·C6H2N3O7−, (III), and C11H17N2O+·C7H6NO2−·H2O, (IV), the effectively planar 4-methoxyphenyl substituent again occupies an equatorial site on the piperazine ring. In (II), two of the nitro groups are disordered over two sets of atomic sites and the bond distances in the anion indicate considerable delocalization of the negative charge over the C atoms of the ring. The ions in (II) are linked by two N—H⋯O hydrogen bonds to form a cyclic, centrosymmetric four-ion aggregate; those in (III) are linked by a combination of N—H⋯O and C—H⋯π(arene) hydrogen bonds to form sheets; and the components of (IV) are linked by N—H⋯O, O—H⋯O and C—H⋯π(arene) hydrogen bonds to form a three-dimensional framework structure. Comparisons are made with the structures of some related compounds. Full Article text
met Bis(4-hydroxy-N-isopropyl-N-methyltryptammonium) fumarate: a new crystalline form of miprocin By scripts.iucr.org Published On :: 2020-03-10 The title compound, bis(4-hydroxy-N-isopropyl-N-methyltryptammonium) (4-HO-MiPT) fumarate (systematic name: bis{[2-(4-hydroxy-1H-indol-3-yl)ethyl](methyl)propan-2-ylazanium} but-2-enedioate), 2C14H21N2O+·C4H2O42−, has a singly protonated tryptammonium cation and one half of a fumarate dianion in the asymmetric unit. The tryptammonium and fumarate ions are held together in one-dimensional chains by N—H⋯O and O—H⋯O hydrogen bonds. These chains are a combination of R42(20) rings, and C22(15) and C44(30) parallel chains along (110). They are further consolidated by N—H⋯π interactions. There are two two-component types of disorder impacting the tryptammonium fragment with a 0.753 (7):0.247 (7) occupancy ratio and one of the fumarate oxygen atoms with a 0.73 (8):0.27 (8) ratio. Full Article text
met Crystal structure, Hirshfeld surface analysis and computational study of 2-chloro-N-[4-(methylsulfanyl)phenyl]acetamide By scripts.iucr.org Published On :: 2020-03-31 In the title compound, C9H10ClNOS, the amide functional group –C(=O)NH– adopts a trans conformation with the four atoms nearly coplanar. This conformation promotes the formation of a C(4) hydrogen-bonded chain propagating along the [010] direction. The central part of the molecule, including the six-membered ring, the S and N atoms, is fairly planar (r.m.s. deviation of 0.014). The terminal methyl group and the C(=O)CH2 group are slightly deviating out-of-plane while the terminal Cl atom is almost in-plane. Hirshfeld surface analysis of the title compound suggests that the most significant contacts in the crystal are H⋯H, H⋯Cl/Cl⋯H, H⋯C/C⋯H, H⋯O/O⋯H and H⋯S/S⋯H. π–π interactions between inversion-related molecules also contribute to the crystal packing. DFT calculations have been performed to optimize the structure of the title compound using the CAM-B3LYP functional and the 6–311 G(d,p) basis set. The theoretical absorption spectrum of the title compound was calculated using the TD–DFT method. The analysis of frontier orbitals revealed that the π–π* electronic transition was the major contributor to the absorption peak in the electronic spectrum. Full Article text
met Intramolecular 1,5-S⋯N σ-hole interaction in (E)-N'-(pyridin-4-ylmethylidene)thiophene-2-carbohydrazide By scripts.iucr.org Published On :: 2020-03-17 The title compound, C11H9N3OS, (I), crystallizes in the monoclinic space group P21/n. The molecular conformation is nearly planar and features an intramolecular chalcogen bond between the thiophene S and the imine N atoms. Within the crystal, the strongest interactions between molecules are the N—H⋯O hydrogen bonds, which organize them into inversion dimers. The dimers are linked through short C—H⋯N contacts and are stacked into layers propagating in the (001) plane. The crystal structure features π–π stacking between the pyridine aromatic ring and the azomethine double bond. The calculated energies of pairwise intermolecular interactions within the stacks are considerably larger than those found for the interactions between the layers. Full Article text
met Crystal structure of 1,4,8,11-tetramethyl-1,4,8,11-tetraazoniacyclotetradecane bis[chloridochromate(VI)] dichloride from synchrotron X-ray data By scripts.iucr.org Published On :: 2020-03-10 The crystal structure of title compound, (C14H36N4)[CrO3Cl]2Cl2, has been determined by synchrotron radiation X-ray crystallography at 220 K. The macrocyclic cation lies across a crystallographic inversion center and hence the asymmetric unit contains one half of the organic cation, one chlorochromate anion and one chloride anion. Both the Cl− anion and chlorochromate Cl atom are involved in hydrogen bonding. In the crystal, hydrogen bonds involving the 1,4,8,11-tetramethyl-1,4,8,11-tetraazoniacyclotetradecane (TMC) N—H groups and C—H groups as donor groups and three O atoms of the chlorochromate and the chloride anion as acceptor groups link the components, giving rise to a three-dimensional network. Full Article text
met Crystal structure of (R,S)-2-hydroxy-4-(methylsulfanyl)butanoic acid By scripts.iucr.org Published On :: 2020-03-17 The title compound, a major animal feed supplement, abbreviated as HMTBA and alternatively called dl-methionine hydroxy analogue, C5H10O3S, (I), was isolated in pure anhydrous monomeric form. The melting point is 302.5 K and the compound crystallizes in the monoclinic space group P21/c, with two conformationally non-equivalent molecules [(IA) and (IB)] in the asymmetric unit. The crystal structure is formed by alternating polar and non-polar layers running along the bc plane and features an extensive hydrogen-bonding network within the polar layers. The Hirshfeld surface analysis revealed a significant contribution of non-polar H⋯H and H⋯S interactions to the packing forces for both molecules. Full Article text
met Synthesis and crystal structures of two 1,3-di(alkyloxy)-2-(methylsulfanyl)imidazolium tetrafluoridoborates By scripts.iucr.org Published On :: 2020-03-17 Two salts were prepared by methylation of the respective imidazoline-2-thione at the sulfur atom, using Meerwein's salt (trimethyloxonium tetrafluoridoborate) in CH2Cl2. 1,3-Dimethoxy-2-(methylsulfanyl)imidazolium tetrafluoridoborate (1), C6H11N2O2S+·BF4−, displays a syn conformation of its two methoxy groups relative to each other whereas the two benzyloxy groups present in 1,3-dibenzyloxy-2-(methylsulfanyl)imidazolium tetrafluoridoborate (2), C18H19N2O2S+·BF4−, adopt an anti conformation. In the molecules of 1 and 2, the methylsulfanyl group is rotated out of the plane of the respective heterocyclic ring. In both crystal structures, intermolecular interactions are dominated by C—H⋯F—B contacts, leading to three-dimensional networks. The tetrafluoridoborate counter-ion of 2 is disordered over three orientations (occupancy ratio 0.42:0.34:0.24), which are related by rotation about one of the B—F bonds. Full Article text
met Crystal structure and Hirshfeld surface analysis of 2-amino-3-hydroxypyridin-1-ium 6-methyl-2,2,4-trioxo-2H,4H-1,2,3-oxathiazin-3-ide By scripts.iucr.org Published On :: 2020-03-27 The asymmetric unit of the title compound, C5H7N2O+·C4H4NO4S−, contains one cation and one anion. The 6-methyl-2,2,4-trioxo-2H,4H-1,2,3-oxathiazin-3-ide anion adopts an envelope conformation with the S atom as the flap. In the crystal, the anions and cations are held together by N—H⋯O, N—H⋯N, O—H⋯O and C—H⋯O hydrogen bonds, thus forming a three-dimensional structure. The Hirshfeld surface analysis and fingerprint plots reveal that the crystal packing is dominated by O⋯H/H⋯O (43.1%) and H⋯H (24.2%) contacts. Full Article text
met Structural investigation of methyl 3-(4-fluorobenzoyl)-7-methyl-2-phenylindolizine-1-carboxylate, an inhibitory drug towards Mycobacterium tuberculosis By scripts.iucr.org Published On :: 2020-03-20 The title compound, C24H18FNO3, crystallizes in the monoclinic centrosymmetric space group P21/n and its molecular conformation is stabilized via C—H⋯O intramolecular interactions. The supramolecular network mainly comprises C—H⋯O, C—H⋯F and C—H⋯π interactions, which contribute towards the formation of the crystal structure. The different intermolecular interactions have been further analysed via Hirshfeld surface analysis and fingerprint plots. Full Article text
met Crystal structure of a new phenyl(morpholino)methanethione derivative: 4-[(morpholin-4-yl)carbothioyl]benzoic acid By scripts.iucr.org Published On :: 2020-03-27 4-[(Morpholin-4-yl)carbothioyl]benzoic acid, C12H13NO3S, a novel phenyl(morpholino)methanethione derivative, crystallizes in the monoclinic space group P21/n. The morpholine ring adopts a chair conformation and the carboxylic acid group is bent out slightly from the benzene ring mean plane. The molecular geometry of the carboxylic group is characterized by similar C—O bond lengths [1.266 (2) and 1.268 (2) Å] as the carboxylate H atom is disordered over two positions. This molecular arrangement leads to the formation of dimers through strong and centrosymmetric low barrier O—H⋯O hydrogen bonds between the carboxylic groups. In addition to these intermolecular interactions, the crystal packing consists of two different molecular sheets with an angle between their mean planes of 64.4 (2)°. The cohesion between the different layers is ensured by C—H⋯S and C—H⋯O interactions. Full Article text
met Crystal structure, Hirshfeld surface and frontier molecular orbital analysis of 10-benzyl-9-(3-ethoxy-4-hydroxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-dione By scripts.iucr.org Published On :: 2020-03-27 In the fused ring system of the title compound, C32H37NO4, the central dihydropyridine ring adopts a flattened boat conformation, the mean and maximum deviations of the dihydropyridine ring being 0.1429 (2) and 0.2621 (2) Å, respectively. The two cyclohexenone rings adopt envelope conformations with the tetrasubstituted C atoms as flap atoms. The benzene and phenyl rings form dihedral angles of 85.81 (2) and 88.90 (2)°, respectively, with the mean plane of the dihydropyridine ring. In the crystal, molecules are linked via an O—H⋯O hydrogen bond, forming a helical chain along the b-axis direction. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (65.2%), O⋯H/H⋯O (18.8%) and C⋯H/H⋯C (13.9%) contacts. Quantum chemical calculations for the frontier molecular orbitals were undertake to determine the chemical reactivity of the title compound. Full Article text
met Crystal structures of (η4-cycloocta-1,5-diene)bis(1,3-dimethylimidazol-2-ylidene)iridium(I) iodide and (η4-cycloocta-1,5-diene)bis(1,3-diethylimidazol-2-ylidene)iridium(I) iodide By scripts.iucr.org Published On :: 2020-04-03 The title complexes, (η4-cycloocta-1,5-diene)bis(1,3-dimethylimidazol-2-ylidene)iridium(I) iodide, [Ir(C5H8N2)2(C8H12)]I, (1) and (η4-cycloocta-1,5-diene)bis(1,3-diethylimidazol-2-ylidene)iridium(I) iodide, [Ir(C7H12N2)2(C8H12)]I, (2), were prepared using a modified literature method. After carrying out the oxidative addition of the amino acid l-proline to [Ir(COD)(IMe)2]I in water and slowly cooling the reaction to room temperature, a suitable crystal of 1 was obtained and analyzed by single-crystal X-ray diffraction at 100 K. Although this crystal structure has previously been reported in the Pbam space group, it was highly disordered and precise atomic coordinates were not calculated. A single crystal of 2 was also obtained by heating the complex in water and letting it slowly cool to room temperature. Complex 1 was found to crystallize in the monoclinic space group C2/m, while 2 crystallizes in the orthorhombic space group Pccn, both with Z = 4. Full Article text
met Crystal structure, Hirshfeld surface analysis and interaction energy and DFT studies of 2-(2,3-dihydro-1H-perimidin-2-yl)-6-methoxyphenol By scripts.iucr.org Published On :: 2020-04-03 The title compound, C18H16N2O2, consists of perimidine and methoxyphenol units, where the tricyclic perimidine unit contains a naphthalene ring system and a non-planar C4N2 ring adopting an envelope conformation with the NCN group hinged by 47.44 (7)° with respect to the best plane of the other five atoms. In the crystal, O—HPhnl⋯NPrmdn and N—HPrmdn⋯OPhnl (Phnl = phenol and Prmdn = perimidine) hydrogen bonds link the molecules into infinite chains along the b-axis direction. Weak C—H⋯π interactions may further stabilize the crystal structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (49.0%), H⋯C/C⋯H (35.8%) and H⋯O/O⋯H (12.0%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. Computational chemistry indicates that in the crystal, the O—HPhnl⋯NPrmdn and N—HPrmdn⋯OPhnl hydrogen-bond energies are 58.4 and 38.0 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap. Full Article text
met Crystal structures of {1,1,1-tris[(salicylaldimino)methyl]ethane}gallium as both a pyridine solvate and an acetonitrile 0.75-solvate and {1,1,1-tris[(salicylaldimino)methyl]ethane}indium dichloro By scripts.iucr.org Published On :: 2020-04-03 The sexadentate ligand 1,1,1-tris[(salicylideneamino)methyl]ethane has been reported numerous times in its triply deprotonated form coordinated to transition metals and lanthanides, yet it has been rarely employed with main-group elements, including in substituted forms. Its structures with gallium and indium are reported as solvates, namely, ({[(2,2-bis{[(2-oxidobenzylidene)amino-κ2N,O]methyl}propyl)imino]methyl}phenololato-κ2N,O)gallium(III) pyridine monosolvate, [Ga(C26H24N3O3)]·C5H5N, the acetonitrile 0.75-solvate, [Ga(C26H24N3O3)]·0.75C2H3N, and ({[(2,2-bis{[(2-oxidobenzylidene)amino-κ2N,O]methyl}propyl)imino]methyl}phenololato-κ2N,O)indium(III) dichloromethane monosolvate, [In(C26H24N3O3)]·CH2Cl2. All three metal complexes are pseudo-octahedral and each structure contains multiple weak C—H⋯O and/or C—H⋯N intermolecular hydrogen-bonding interactions. The syntheses and additional characterization in the forms of melting points, high-resolution mass spectra, infra-red (IR) spectra, and 1H and 13C NMR spectra are also reported. Full Article text
met Crystal structure of N'-[4-(dimethylamino)benzylidene]furan-2-carbohydrazide monohydrate By scripts.iucr.org Published On :: 2020-04-09 The condensation of 2-furoic hydrazide and 4-dimethyl aminobenzaldehyde in ethanol yielded a yellow solid formulated as the title compound, C14H15N3O2·H2O. The crystal packing is stabilized by intermolecular O(water)—H⋯O,N(carbohydrazide) and N—H⋯O(water) hydrogen bonds, which form a two-dimensional network along the bc plane. Additional C—H⋯O interactions link the molecules into a three-dimensional network. The dihedral angle between the mean planes of the benzene and the furan ring is 34.47 (6)°. The carbohydrazide moiety, i.e., the C=N—N—C=O fragment and the benzene ring are almost coplanar, with an angle of 6.75 (9)° between their mean planes. Full Article text
met Synthesis and crystal structures of tetrameric [2-(4,4-dimethyl-2-oxazolin-2-yl)anilido]sodium and tris[2-(4,4-dimethyl-2-oxazolin-2-yl)anilido]ytterbium(III) By scripts.iucr.org Published On :: 2020-04-21 Reaction of 2-(4,4-dimethyl-2-oxazolin-2-yl)aniline (H2-L1) with one equivalent of Na[N(SiMe3)2] in toluene afforded pale-yellow crystals of tetrameric poly[bis[μ3-2-(4,4-dimethyl-2-oxazolin-2-yl)anilinido][μ2-2-(4,4-dimethyl-2-oxazolin-2-yl)aniline]tetrasodium(I)], [Na4(C11H13N2O)4]n or [Na4(H-L1)4]n (2), in excellent yield. Subsequent reaction of [Na4(H-L1)4]n (2) with 1.33 equivalents of anhydrous YbCl3 in a 50:50 mixture of toluene–THF afforded yellow crystals of tris[2-(4,4-dimethyl-2-oxazolin-2-yl)anilinido]ytterbium(III), [Yb(C11H13N2O)3] or Yb(H-L1)3 (3) in moderate yield. Direct reaction of three equivalents of 2-(4',4'-dimethyl-2'-oxazolinyl)aniline (H2-L1) with Yb[N(SiMe3)2]3 in toluene resulted in elimination of hexamethyldisilazane, HN(SiMe3)2, and produced Yb(H-L1)3 (3) in excellent yield. The structure of 2 consists of tetrameric Na4(H-L1)4 subunits in which each Na+ cation is bound to two H-L1 bridging bidentate ligands and these subunits are connected into a polymeric chain by two of the four oxazoline O atoms bridging to Na+ cations in the adjacent tetramer. This results in two 4-coordinate and two 5-coordinate Na+ cations within each tetrameric unit. The structure of 3 consists of a distorted octahedron where the bite angle of ligand L1 ranges between 74.72 (11) and 77.79 (11) degrees. The oxazoline (and anilide) N atoms occupy meridional sites such that for one ligand an anilide nitrogen is trans to an oxazoline nitrogen while for the other two oxazoline N atoms are trans to each other. This results in a significantly longer Yb—N(oxazoline) distance [2.468 (3) Å] for the bond trans to the anilide compared to those for the oxazoline N atoms trans to one another [2.376 (3), 2.390 (3) Å]. Full Article text
met Crystal structure of bis(1-mesityl-1H-imidazole-κN3)diphenylboron trifluoromethanesulfonate By scripts.iucr.org Published On :: 2020-04-21 The solid-state structure of bis(1-mesityl-1H-imidazole-κN3)diphenylboron trifluoromethanesulfonate, C36H38BN4+·CF3SO3− or (Ph2B(MesIm)2OTf), is reported. Bis(1-mesityl-1H-imidazole-κN3)diphenylboron (Ph2B(MesIm)2+) is a bulky ligand that crystallizes in the orthorhombic space group Pbcn. The asymmetric unit contains one Ph2B(MesIm)2+ cationic ligand and one trifluoromethanesulfonate anion that balances the positive charge of the ligand. The tetrahedral geometry around the boron center is distorted as a result of the steric bulk of the phenyl groups. Weak interactions, such as π–π stacking are present in the crystal structure. Full Article text
met Functionalized 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-(4-substituted-phenyl)prop-2-en-1-ones: synthetic pathway, and the structures of six examples By scripts.iucr.org Published On :: 2020-04-21 Five examples each of 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-ones and the corresponding 1-(4-azidophenyl)-3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones have been synthesized in a highly efficient manner, starting from a common source precursor, and structures have been determined for three examples of each type. In each of 3-[5-(2-chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-one, C28H21ClN2O3, (Ib), the isomeric 3-[5-(2-chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-one, (Ic), and 3-[3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C32H24N2O3, (Ie), the molecules are linked into chains of rings, formed by two independent C—H⋯O hydrogen bonds in (Ib) and by a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds in each of (Ic) and (Ie). There are no direction-specific intermolecular interactions in the structure of 1-(4-azidophenyl)-3-[3-methyl-5-(2-methylphenoxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C26H21N5O2, (IIa). In 1-(4-azidophenyl)-3-[5-(2,4-dichlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C25H17Cl2N5O2, (IId), the dichlorophenyl group is disordered over two sets of atomic sites having occupancies 0.55 (4) and 0.45 (4), and the molecules are linked by a single C—H⋯O hydrogen bond to form cyclic, centrosymmetric R22(20) dimers. Similar dimers are formed in 1-(4-azidophenyl)-3-[3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C29H21N5O2, (IIe), but here the dimers are linked into a chain of rings by two independent C—H..π(arene) hydrogen bonds. Comparisons are made between the molecular conformations within both series of compounds. Full Article text
met 2-[(2,4,6-Trimethylbenzene)sulfonyl]phthalazin-1(2H)-one: crystal structure, Hirshfeld surface analysis and computational study By scripts.iucr.org Published On :: 2020-04-21 The X-ray crystal structure of the title phthalazin-1-one derivative, C17H16N2O3S {systematic name: 2-[(2,4,6-trimethylbenzene)sulfonyl]-1,2-dihydrophthalazin-1-one}, features a tetrahedral sulfoxide-S atom, connected to phthalazin-1-one and mesityl residues. The dihedral angle [83.26 (4)°] between the organic substituents is consistent with the molecule having the shape of the letter V. In the crystal, phthalazinone-C6-C—H⋯O(sulfoxide) and π(phthalazinone-N2C4)–π(phthalazinone-C6) stacking [inter-centroid distance = 3.5474 (9) Å] contacts lead to a linear supramolecular tape along the a-axis direction; tapes assemble without directional interactions between them. The analysis of the calculated Hirshfeld surfaces confirm the importance of the C—H⋯O and π-stacking interactions but, also H⋯H and C—H⋯C contacts. The calculation of the interaction energies indicate the importance of dispersion terms with the greatest energies calculated for the C—H⋯O and π-stacking interactions. Full Article text
met Crystal structure and DFT computational studies of (E)-2,4-di-tert-butyl-6-{[3-(trifluoromethyl)benzyl]iminomethyl}phenol By scripts.iucr.org Published On :: 2020-04-24 The title compound, C23H28F3NO, is an ortho-hydroxy Schiff base compound, which adopts the enol–imine tautomeric form in the solid state. The molecular structure is not planar and the dihedral angle between the planes of the aromatic rings is 85.52 (10)°. The trifluoromethyl group shows rotational disorder over two sites, with occupancies of 0.798 (6) and 0.202 (6). An intramolecular O—H⋯N hydrogen bonding generates an S(6) ring motif. The crystal structure is consolidated by C—H⋯π interactions. The molecular structure was optimized via density functional theory (DFT) methods with the B3LYP functional and LanL2DZ basis set. The theoretical structure is in good agreement with the experimental data. The frontier orbitals and molecular electrostatic potential map were also examined by DFT computations. Full Article text
met Crystal structure and Hirshfeld surface analysis of 4-{[(anthracen-9-yl)methyl]amino}benzoic acid dimethylformamide monosolvate By scripts.iucr.org Published On :: 2020-04-24 The title compound, C22H17NO2·C3H7NO, was synthesized by condensation of an aromatic aldehyde with a secondary amine and subsequent reduction. It was crystallized from a dimethylformamide solution as a monosolvate, C22H17NO2·C3H7NO. The aromatic molecule is non-planar with a dihedral angle between the mean planes of the aniline moiety and the methyl anthracene moiety of 81.36 (8)°. The torsion angle of the Caryl—CH2—NH—Caryl backbone is 175.9 (2)°. The crystal structure exhibits a three-dimensional supramolecular network, resulting from hydrogen-bonding interactions between the carboxylic OH group and the solvent O atom as well as between the amine functionality and the O atom of the carboxylic group and additional C—H⋯π interactions. Hirshfeld surface analysis was performed to quantify the intermolecular interactions. Full Article text
met Hydrogen-bonding patterns in 2,2-bis(4-methylphenyl)hexafluoropropane pyridinium and ethylenediammonium salt crystals By scripts.iucr.org Published On :: 2020-04-24 The crystal structures of two salt crystals of 2,2-bis(4-methylphenyl)hexafluoropropane (Bmphfp) with amines, namely, dipyridinium 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoate 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoic acid, 2C5H6N+·C17H8F6O42−·C17H10F6O4, (1), and a monohydrated ethylenediammonium salt ethane-1,2-diaminium 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzoate monohydrate, C2H10N22+·C17H8F6O42−·H2O, (2), are reported. Compounds 1 and 2 crystallize, respectively, in space group P21/c with Z' = 2 and in space group Pbca with Z' = 1. The crystals of compound 1 contain neutral and anionic Bmphfp molecules, and form a one-dimensional hydrogen-bonded chain motif. The crystals of compound 2 contain anionic Bmphfp molecules, which form a complex three-dimensional hydrogen-bonded network with the ethylenediamine and water molecules. Full Article text
met Synthesis and crystal structure of a pentacopper(II) 12-metallacrown-4: cis-diaquatetrakis(dimethylformamide-κO)manganese(II) tetrakis(μ3-N,2-dioxidobenzene-1-carboximidate)pentacopper(II) By scripts.iucr.org Published On :: 2020-04-30 The title compound, [Mn(C3H7NO)4(H2O)2][Cu5(C7H4NO3)4]·C3H7NO or cis-[Mn(H2O)2(DMF)4]{Cu[12-MCCu(II)N(shi)-4]}·DMF, where MC is metallacrown, shi3− is salicylhydroximate, and DMF is N,N-dimethylformamide, crystallizes in the monoclinic space group P21/n. Two crystallographically independent metallacrown anions are present in the structure, and both anions exhibit minor main molecule disorder by an approximate (non-crystallographic) 180° rotation with occupancy ratios of 0.9010 (9) to 0.0990 (9) for one anion and 0.9497 (8) to 0.0503 (8) for the other. Each pentacopper(II) metallacrown contains four CuII ions in the MC ring and a CuII ion captured in the central cavity. Each CuII ion is four-coordinate with a square-planar geometry. The anionic {Cu[12-MCCu(II)N(shi)-4]}2− is charged-balanced by the presence of a cis-[Mn(H2O)2(DMF)4]2+ cation located in the lattice. In addition, the octahedral MnII counter-cation is hydrogen bonded to both MC anions via the coordinated water molecules of the MnII ion. The water molecules form hydrogen bonds with the phenolate and carbonyl oxygen atoms of the shi3− ligands of the MCs. Full Article text
met Synthesis, crystal structure and Hirshfeld surface analysis of N-(4-chlorophenyl)-5-cyclopropyl-1-(4-methoxyphenyl)-1H-1,2,3-triazole-4-carboxamide By scripts.iucr.org Published On :: 2020-04-30 The title compound, C19H17ClN4O2, was obtained via a two-step synthesis involving the enol-mediated click Dimroth reaction of 4-azidoanisole with methyl 3-cyclopropyl-3-oxopropanoate leading to the 5-cyclopropyl-1-(4-methoxyphenyl)-1H-1,2,3-triazole-4-carboxylic acid and subsequent acid amidation with 4-chloroaniline by 1,1'-carbonyldiimidazole (CDI). It crystallizes in space group P21/n, with one molecule in the asymmetric unit. In the extended structure, two molecules arranged in a near coplanar fashion relative to the triazole ring planes are interconnected by N—H⋯N and C—H⋯N hydrogen bonds into a homodimer. The formation of dimers is a consequence of the above interaction and the edge-to-face stacking of aromatic rings, which are turned by 58.0 (3)° relative to each other. The dimers are linked by C—H⋯O interactions into ribbons. DFT calculations demonstrate that the frontier molecular orbitals are well separated in energy and the HOMO is largely localized on the 4-chlorophenyl amide motif while the LUMO is associated with aryltriazole grouping. A Hirshfeld surface analysis was performed to further analyse the intermolecular interactions. Full Article text
met Equatorial aberration of powder diffraction data collected with an Si strip X-ray detector by a continuous-scan integration method By scripts.iucr.org Published On :: 2020-05-05 Exact and approximate mathematical formulas of equatorial aberration for powder diffraction data collected with an Si strip X-ray detector in continuous-scan integration mode are presented. An approximate formula is applied to treat the experimental data measured with a commercial powder diffractometer. Full Article text
met Calculation of total scattering from a crystalline structural model based on experimental optics parameters By scripts.iucr.org Published On :: 2020-05-05 Total scattering measurements enable understanding of the structural disorder in crystalline materials by Fourier transformation of the total structure factor, S(Q), where Q is the magnitude of the scattering vector. In this work, the direct calculation of total scattering from a crystalline structural model is proposed. To calculate the total scattering intensity, a suitable Q-broadening function for the diffraction profile is needed because the intensity and the width depend on the optical parameters of the diffraction apparatus, such as the X-ray energy resolution and divergence, and the intrinsic parameters. X-ray total scattering measurements for CeO2 powder were performed at beamline BL04B2 of the SPring-8 synchrotron radiation facility in Japan for comparison with the calculated S(Q) under various optical conditions. The evaluated Q-broadening function was comparable to the full width at half-maximum of the Bragg peaks in the experimental total scattering pattern. The proposed calculation method correctly accounts for parameters with Q dependence such as the atomic form factor and resolution function, enables estimation of the total scattering factor, and facilitates determination of the reduced pair distribution function for both crystalline and amorphous materials. Full Article text
met Symmetry-mode analysis for intuitive observation of structure–property relationships in the lead-free antiferroelectric (1−x)AgNbO3–xLiTaO3 By scripts.iucr.org Published On :: 2019-06-21 Functional materials are of critical importance to electronic and smart devices. A deep understanding of the structure–property relationship is essential for designing new materials. In this work, instead of utilizing conventional atomic coordinates, a symmetry-mode approach is successfully used to conduct structure refinement of the neutron powder diffraction data of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics. This provides rich structural information that not only clarifies the controversial symmetry assigned to pure AgNbO3 but also explains well the detailed structural evolution of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics, and builds a comprehensive and straightforward relationship between structural distortion and electrical properties. It is concluded that there are four relatively large-amplitude major modes that dominate the distorted Pmc21 structure of pure AgNbO3, namely a Λ3 antiferroelectric mode, a T4+ a−a−c0 octahedral tilting mode, an H2 a0a0c+/a0a0c− octahedral tilting mode and a Γ4− ferroelectric mode. The H2 and Λ3 modes become progressively inactive with increasing x and their destabilization is the driving force behind the composition-driven phase transition between the Pmc21 and R3c phases. This structural variation is consistent with the trend observed in the measured temperature-dependent dielectric properties and polarization–electric field (P-E) hysteresis loops. The mode crystallography applied in this study provides a strategy for optimizing related properties by tuning the amplitudes of the corresponding modes in these novel AgNbO3-based (anti)ferroelectric materials. Full Article text
met Competitive formation between 2D and 3D metal-organic frameworks: insights into the selective formation and lamination of a 2D MOF By scripts.iucr.org Published On :: 2019-06-12 The structural dimension of metal–organic frameworks (MOFs) is of great importance in defining their properties and thus applications. In particular, 2D layered MOFs are of considerable interest because of their useful applications, which are facilitated by unique structural features of 2D materials, such as a large number of open active sites and high surface areas. Herein, this work demonstrates a methodology for the selective synthesis of a 2D layered MOF in the presence of the competitive formation of a 3D MOF. The ratio of the reactants, metal ions and organic building blocks used during the reaction is found to be critical for the selective formation of a 2D MOF, and is associated with its chemical composition. In addition, the well defined and uniform micro-sized 2D MOF particles are successfully synthesized in the presence of an ultrasonic dispersion. Moreover, the laminated 2D MOF layers are directly synthesized via a modified bottom-up lamination method, a combination of chemical and physical stimuli, in the presence of surfactant and ultrasonication. Full Article text
met DeepRes: a new deep-learning- and aspect-based local resolution method for electron-microscopy maps By scripts.iucr.org Published On :: 2019-09-18 In this article, a method is presented to estimate a new local quality measure for 3D cryoEM maps that adopts the form of a `local resolution' type of information. The algorithm (DeepRes) is based on deep-learning 3D feature detection. DeepRes is fully automatic and parameter-free, and avoids the issues of most current methods, such as their insensitivity to enhancements owing to B-factor sharpening (unless the 3D mask is changed), among others, which is an issue that has been virtually neglected in the cryoEM field until now. In this way, DeepRes can be applied to any map, detecting subtle changes in local quality after applying enhancement processes such as isotropic filters or substantially more complex procedures, such as model-based local sharpening, non-model-based methods or denoising, that may be very difficult to follow using current methods. It performs as a human observer expects. The comparison with traditional local resolution indicators is also addressed. Full Article text
met R3c-type LnNiO3 (Ln = La, Ce, Nd, Pm, Gd, Tb, Dy, Ho, Er, Lu) half-metals with multiple Dirac cones: a potential class of advanced spintronic materials By scripts.iucr.org Published On :: 2019-10-16 In the past three years, Dirac half-metals (DHMs) have attracted considerable attention and become a high-profile topic in spintronics becuase of their excellent physical properties such as 100% spin polarization and massless Dirac fermions. Two-dimensional DHMs proposed recently have not yet been experimentally synthesized and thus remain theoretical. As a result, their characteristics cannot be experimentally confirmed. In addition, many theoretically predicted Dirac materials have only a single cone, resulting in a nonlinear electromagnetic response with insufficient intensity and inadequate transport carrier efficiency near the Fermi level. Therefore, after several attempts, we have focused on a novel class of DHMs with multiple Dirac crossings to address the above limitations. In particular, we direct our attention to three-dimensional bulk materials. In this study, the discovery via first principles of an experimentally synthesized DHM LaNiO3 with many Dirac cones and complete spin polarization near the Fermi level is reported. It is also shown that the crystal structures of these materials are strongly correlated with their physical properties. The results indicate that many rhombohedral materials with the general formula LnNiO3 (Ln = La, Ce, Nd, Pm, Gd, Tb, Dy, Ho, Er, Lu) in the space group R3c are potential DHMs with multiple Dirac cones. Full Article text
met Structure-based mechanism of cysteine-switch latency and of catalysis by pappalysin-family metallopeptidases By scripts.iucr.org Published On :: 2020-01-01 Tannerella forsythia is an oral dysbiotic periodontopathogen involved in severe human periodontal disease. As part of its virulence factor armamentarium, at the site of colonization it secretes mirolysin, a metallopeptidase of the unicellular pappalysin family, as a zymogen that is proteolytically auto-activated extracellularly at the Ser54–Arg55 bond. Crystal structures of the catalytically impaired promirolysin point mutant E225A at 1.4 and 1.6 Å revealed that latency is exerted by an N-terminal 34-residue pro-segment that shields the front surface of the 274-residue catalytic domain, thus preventing substrate access. The catalytic domain conforms to the metzincin clan of metallopeptidases and contains a double calcium site, which acts as a calcium switch for activity. The pro-segment traverses the active-site cleft in the opposite direction to the substrate, which precludes its cleavage. It is anchored to the mature enzyme through residue Arg21, which intrudes into the specificity pocket in cleft sub-site S1'. Moreover, residue Cys23 within a conserved cysteine–glycine motif blocks the catalytic zinc ion by a cysteine-switch mechanism, first described for mammalian matrix metallopeptidases. In addition, a 1.5 Å structure was obtained for a complex of mature mirolysin and a tetradecapeptide, which filled the cleft from sub-site S1' to S6'. A citrate molecule in S1 completed a product-complex mimic that unveiled the mechanism of substrate binding and cleavage by mirolysin, the catalytic domain of which was already preformed in the zymogen. These results, including a preference for cleavage before basic residues, are likely to be valid for other unicellular pappalysins derived from archaea, bacteria, cyanobacteria, algae and fungi, including archetypal ulilysin from Methanosarcina acetivorans. They may further apply, at least in part, to the multi-domain orthologues of higher organisms. Full Article text
met Investigation of growth characteristics and semimetal–semiconductor transition of polycrystalline bismuth thin films By scripts.iucr.org Published On :: 2020-01-01 The preferred orientation growth characteristics and surface roughness of polycrystalline bismuth (Bi) thin films fabricated on glass substrates using the molecular beam epitaxy method were investigated at temperatures ranging from 18 to 150°C. The crystallization and morphology were analyzed in detail and the polycrystalline metal film structure-zone model (SZM) was modified to fit the polycrystalline Bi thin film. The boundary temperature between Zone T and Zone II in the SZM shifted to higher temperatures with the increase in film thickness or the decrease of growth rate. Furthermore, the effect of the thickness and surface roughness on the transport properties was investigated, especially for Bi thin films in Zone II. A two-transport channels model was adopted to reveal the influence of the film thickness on the competition between the metallic surface states and the semiconducting bulk states, which is consistent with the results of Bi single-crystal films. Therefore, the polycrystalline Bi thin films are expected to replace the single-crystal films in the application of spintronic devices. Full Article text
met Distinguishing contributions of ceramic matrix and binder metal to the plasticity of nanocrystalline cermets By scripts.iucr.org Published On :: 2020-01-01 Using the typical WC–Co cemented carbide as an example, the interactions of dislocations within the ceramic matrix and the binder metal, as well as the possible cooperation and competition between the matrix and binder during deformation of the nanocrystalline cermets, were studied by molecular dynamics simulations. It was found that at the same level of strain, the dislocations in Co have more complex configurations in the cermet with higher Co content. With loading, the ratio between mobile and sessile dislocations in Co becomes stable earlier in the high-Co cermet. The strain threshold for the nucleation of dislocations in WC increases with Co content. At the later stage of deformation, the growth rate of WC dislocation density increases more rapidly in the cermet with lower Co content, which exhibits an opposite tendency compared with Co dislocation density. The relative contribution of Co and WC to the plasticity of the cermet varies in the deformation process. With a low Co content, the density of WC dislocations becomes higher than that of Co dislocations at larger strains, indicating that WC may contribute more than Co to the plasticity of the nanocrystalline cermet at the final deformation stage. The findings in the present work will be applicable to a large variety of ceramic–metal composite materials. Full Article text