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1.
《Acta Crystallographica. Section C, Structural Chemistry》2018,74(8):876-881
The title compound, C19H14N2O4, was found to have two crystal polymorphs, in which the molecular structures of the diacetylenic compound are broadly similar. The main structural difference between the polymorphs concerns the intermolecular hydrogen‐bonding motifs adopted, namely a one‐dimensional zigzag polymer linked by N—H…N(py) (py is pyridine) interactions in polymorph I and a centrosymmetric dimeric motif formed by N—H…O=C interactions in polymorph II. The diacetylene cores of the molecules stack along the a and b axes in polymorphs I and II, respectively. It was found that only the molecular arrangement in polymorph II satisfies Baughman's criterion to afford polydiacetylenes (PDAs) by thermal annealing or irradiation with light. This predicted polymerization activity was confirmed by experiment. 相似文献
2.
Madeleine Helliwell Synnve Liaaen‐Jensen James Wilkinson 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(5):o252-o256
Two polymorphs of 20‐desmethyl‐β‐carotene (systematic name: 20‐nor‐β,β‐carotene), C39H54, in monoclinic and triclinic space groups, were formed in the same vial by recrystallization from pyridine and water. Each polymorph crystallizes with the complete molecule as the asymmetric unit, and the two polymorphs show differing patterns of disorder. The β end rings of both polymorphs have the 6‐s‐cis conformation, and are twisted out of the plane of the polyene chain by angles of −53.2 (8) and 47.3 (8)° for the monoclinic polymorph, and −43.6 (3) and 56.1 (3)° for the triclinic polymorph. The cyclohexene end groups are in the half‐chair conformation, but the triclinic polymorph shows disorder of one ring. Overlay of the molecules shows that they differ in the degree of nonplanarity of the polyene chains and the angles of twist of the end rings. The packing arrangements of the two polymorphs are quite different, with the monoclinic polymorph showing short intermolecular contacts of the disordered methyl groups with adjacent polyene chain atoms, and the triclinic polymorph showing π–π stacking interactions of the almost parallel polyene chains. The determination of the crystal structures of the two title polymorphs of 20‐desmethyl‐β‐carotene allows information to be gained regarding the structural effects on the polyene chain, as well as on the end groups, versus that of the parent compound β‐carotene. The absence of the methyl group is known to have an impact on various functions of the title compound. 相似文献
3.
Afef Ghouili Ameni Brahmia Rached Ben Hassen 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(10):873-877
A new polymorph (denoted polymorph II) of 3‐acetyl‐4‐hydroxy‐2H‐chromen‐2‐one, C11H8O4, was obtained unexpectedly during an attempt to recrystallize the compound from salt–melted ice, and the structure is compared with that of the original polymorph (denoted polymorph I) [Lyssenko & Antipin (2001). Russ. Chem. Bull. 50 , 418–431]. Strong intramolecular O—H...O hydrogen bonds are observed equally in the two polymorphs [O...O = 2.4263 (13) Å in polymorph II and 2.442 (1) Å in polymorph I], with a slight delocalization of the hydroxy H atom towards the ketonic O atom in polymorph II [H...O = 1.32 (2) Å in polymorph II and 1.45 (3) Å in polymorph I]. In both crystal structures, the packing of the molecules is dominated and stabilized by weak intermolecular C—H...O hydrogen bonds. Additional π–π stacking interactions between the keto–enol hydrogen‐bonded rings stabilize polymorph I [the centres are separated by 3.28 (1) Å], while polymorph II is stabilized by interactions between α‐pyrone rings, which are parallel to one another and separated by 3.670 (5) Å. 相似文献
4.
Sofiane Mekki Valrie Rolland Salima Bellahouel Arie van der Lee Marc Rolland 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(8):o301-o305
Two concomitant polymorphs, (I) and (II), of a β‐benzyl‐β‐hydroxyaspartate analogue [systematic name: dibenzyl 2‐benzyl‐2‐hydroxy‐3‐(4‐methylphenylsulfonamido)succinate], C32H31NO7S, crystallize from a mixture of ethyl acetate and cyclohexane at ambient temperature. The structure of (I) has triclinic (P) symmetry and that of (II) monoclinic (P21/c) symmetry. Both crystal structures are made up of a stacking of homochiral racemic dimers (2S,3S and 2R,3R) which are internally connected by a similar R22(9) hydrogen‐bonding pattern consisting of intermolecular N—H...O and O—H...O hydrogen bonds. The centroid of the racemic dimer lies on an inversion centre. The main structural difference between the two polymorphs is the conformational orientation of two of the four aromatic rings present in the molecule. Polymorph (II) is found to be twinned by reticular merohedry with twin index 3 and twin fractions 0.854 (1) and 0.146 (1). 相似文献
5.
Koji Kubono Kunihiko Yokoi 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(9):o535-o537
The title compound, C18H18Cl4N2O2, crystallizes as monoclinic and orthorhombic polymorphs from CHCl3–CH3OH solution. In both polymorphic forms, the molecule lies on a crystallographic centre of inversion (at the piperazine ring centroid) and exhibits an intramolecular O—H...N hydrogen bond. In the monoclinic polymorph (space group P21/c), the molecules are linked by intermolecular C—H...Cl hydrogen bonds into a ribbon sheet built from R88(34) rings. In the orthorhombic polymorph (space group Pbcn), the molecules are linked by intermolecular C—H...O hydrogen bonds into a ribbon sheet of R66(34) rings. The sheets in the orthorhombic polymorph are crosslinked into a three‐dimensional framework by π–π stacking interactions. 相似文献
6.
Dragana Stevanovi Anka Pejovi Sladjana B. Novakovi Goran A. Bogdanovi Vladimir Divjakovi Rastko D. Vukievi 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(2):m37-m40
Recrystallization of the title compound, [Fe(C5H5)(C14H13N2O3)], from a mixture of n‐hexane and dichloromethane gave the new polymorph, denoted (I), which crystallizes in the same space group (P) as the previously reported structure, denoted (II). The Fe—C distances in (I) range from 2.015 (3) to 2.048 (2) Å and the average value of the C—C bond lengths in the two cyclopentadienyl (Cp) rings is 1.403 (13) Å. As indicated by the smallest C—Cg1—Cg2—C torsion angle of 1.4° (Cg1 and Cg2 are the centroids of the two Cp rings), the orientation of the Cp rings in (I) is more eclipsed than in the case of (II), for which the value was 15.3°. Despite the pronounced conformational similarity between (I) and (II), the formation of self‐complementary N—H...O hydrogen‐bonded dimers represents the only structural motif common to the two polymorphs. In the extended structure, molecules of (I) utilize C—H...O hydrogen bonds and, unlike (II), an extensive set of intermolecular C—H...π interactions. Fingerprint plots based on Hirshfeld surfaces are used to compare the packing of the two polymorphs. 相似文献
7.
Alexander D. Roshal Artur Sikorski Vyacheslav N. Baumer Alexander I. Novikov Jerzy Baejowski 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):o626-o630
Crystallization (from ethyl acetate solution) of 2‐(4‐chlorophenyl)‐4‐methylchromenium perchlorate, C16H12ClO+·;ClO4−, (I), yields two monoclinic polymorphs with the space groups P21/n [polymorph (Ia)] and P21/c [polymorph (Ib)]; in both cases, Z = 4. Cations and anions, disordered in polymorph (Ib), form ion pairs in both polymorphs as a result of Cl—O...π interactions. Related by a centre of symmetry, neighbouring ion pairs in polymorph (Ia) are linked viaπ–π interactions between cationic fragments, and the resulting dimers are linked through a network of C—H...O(perchlorate) interactions between adjacent cations and anions. The ion pairs in polymorph (Ib), arranged in pairs of columns along the a axis, are linked through a network of C—H...O(perchlorate), C—Cl...π, π–π and C—Cl...O(perchlorate) interactions. The aromatic skeletons in polymorph (Ia) are parallel in the cationic fragments involved in dimers, but nonparallel in adjacent ion pairs not constituting dimers. In polymorph (Ib), these skeletons are parallel in pairs of columns, but nonparallel in adjacent pairs of columns; this is visible as a herring‐bone pattern. Differences in the crystal structures of the polymorphs are most probably the cause of their different colours. 相似文献
8.
David B. Cordes Guoxiong Hua Alexandra M. Z. Slawin J. Derek Woollins 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(12):o509-o514
Two polymorphs of 2,5‐diphenyl‐1,3,4‐selenadiazole, C14H10N2Se, denoted (Ia) and (Ib), and a new polymorph of 2,5‐bis(thiophen‐2‐yl)‐1,3,4‐selenadiazole, C10H6N2S2Se, (IIb), form on crystallization of the compounds, prepared using Woollins' reagent (2,4‐diphenyl‐1,3‐diselenadiphosphetane 2,4‐diselenide). These compounds, along with 2‐(4‐chlorophenyl)‐5‐phenyl‐1,3,4‐selenadiazole, C14H9ClN2Se, (III), and 2‐(furan‐2‐yl)‐5‐(p‐tolyl)‐1,3,4‐selenadiazole, C13H10N2OSe, (IV), show similar intermolecular interactions, with π–π stacking, C—H...π interactions and weak hydrogen bonds typically giving rise to molecular chains. However, the combination of interactions differs in each case, giving rise to different packing arrangements. In polymorph (Ib), the molecule lies across a crystallographic twofold rotation axis, and (IV) has two independent molecules in the asymmetric unit. 相似文献
9.
Tatiana N. Drebushchak Nikita V. Chukanov Elena V. Boldyreva 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(12):o623-o625
The ɛ‐form of chlorpropamide [systematic name: 4‐chloro‐N‐(propylaminocarbonyl)benzenesulfonamide], C10H13ClN2O3S, has been obtained as single crystals from solution (and not as a polycrystalline sample by heating the α‐, γ‐ or δ‐forms). The results of anisotropic structure refinements for the ɛ‐ and δ‐forms are reported. The density of the δ‐polymorph is the highest, and that of the ɛ‐polymorph the lowest, among the five known chlorpropamide polymorphs. The main intermolecular hydrogen‐bonding pattern in polymorphs δ and ɛ is the same as in polymorphs α, β and γ, but the conformations differ. The densities of the polymorphs were found to depend on the molecular conformations. 相似文献
10.
Anastasiya Bashkirava Philip C. Andrews Dr. Peter C. Junk Prof. Evan G. Robertson Dr. Leone Spiccia Prof. Nafty Vanderhoek Dr. 《化学:亚洲杂志》2007,2(4):530-538
Three conformational polymorphs of N‐(4′‐methoxyphenyl)‐3‐bromothiobenzamide, yellow α, orange β, and yellow γ, have been identified by single‐crystal X‐ray diffraction. The properties and structure of the polymorphs were examined with FT Raman, FTIR (ATR), and UV/Vis spectroscopy, as well as differential scanning calorimetry. Computational data on rotational barriers in the isolated gas‐phase molecule indicate that the molecular conformation found in the α form is energetically preferred, but only by around 2 kJ mol?1 over the γ conformation. The planar molecular structure found in the β form is destabilized by 10–14 kJ mol?1, depending on the calculation method. However, experimental evidence suggests that the β polymorph is the most stable crystalline phase at room temperature. This is attributed to the relative planarity of this structure, which allows more and stronger intermolecular interactions, that is, more energetically effective packing. Calculated electronic‐absorption maxima were in agreement with experimental spectra. 相似文献
11.
Alain Collas Matthias Zeller Frank Blockhuys 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(5):o171-o174
Two polymorphs of (E,E)‐N,N′‐bis(4‐nitrobenzylidene)benzene‐1,4‐diamine, C20H14N4O4, (I), have been identified. In each case, the molecule lies across a crystallographic inversion centre. The supramolecular structure of the first polymorph, (I‐1), features stacking based on π–π interactions assisted by weak hydrogen bonds involving the nitro groups. The second polymorph, (I‐2), displays a perpendicular arrangement of molecules linked via the nitro groups, combined with weak C—H...O hydrogen bonds. Both crystal structures are compared with that of the carbon analogue (E,E)‐1,4‐bis[2‐(4‐nitrophenyl)ethenyl]benzene, (II). 相似文献
12.
Doyle Britton Frank B. Mallory Clelia W. Mallory 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(4):o235-o238
The molecular structures of 4,7‐dichlorobenzo[c]furazan 1‐oxide, C6H2Cl2N2O2, (I), and 4,7‐dibromobenzo[c]furazan 1‐oxide, C6H2Br2N2O2, (II), are normal. Compound (I) occurs in two polymorphic forms. One polymorph contains one molecule in the asymmetric unit, organized into two‐dimensional sheets involving intermolecular N?Cl and O?Cl interactions. The second polymorph has three molecules in the asymmetric unit, organized into two crystallographically different two‐dimensional sheets with similar interactions. Compound (II) is isomorphous with the second polymorph of (I). The three two‐dimensional sheets in the two polymorphs comprise a set of three two‐dimensional polymorphic arrangements. 相似文献
13.
Doyle Britton Wayland E. Noland Christopher M. Clark 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(4):o187-o190
5‐Iodobenzofurazan 1‐oxide (systematic name: 5‐iodobenzo‐1,2,5‐oxadiazole 1‐oxide), C6H3IN2O2, occurs in two polymorphic forms, both monoclinic in P21/c with Z′ = 2. The intermolecular interactions in the two polymorphs are quite different. In polymorph (I), there are strong intermolecular I...O interactions, with I...O distances of 3.114 (8) and 3.045 (8) Å. In polymorph (II), there are strong intermolecular I...N interactions, with I...N distances of 3.163 (4) and 3.175 (5) Å. In (I), there is about 15% disorder in one molecule and about 5% in the other. In both polymorphs, there are pseudosymmetric relationships between the crystallographically independent molecules. 相似文献
14.
Vasu K. A. Nirmala Deepak Chopra S. Mohan J. Saravanan 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(9):o636-o638
The compounds 2‐{[(E)‐(4‐methoxyphenyl)methylene]amino}‐N‐(3‐methylphenyl)‐4,5,6,7‐tetrahydro‐1‐benzothiophene‐3‐carboxamide, C24H24N2O2S, (I), and N‐(4‐methylphenyl)‐2‐{[(E)‐(4‐methylphenyl)methylene]amino}‐4,5,6,7‐tetrahydro‐1‐benzothiophene‐3‐carboxamide, C24H24N2OS, (II), show antibacterial and antifungal activities. The m‐toluidine ring in (I) and the p‐toluidine ring in (II) are coplanar with their respective thiophene rings. In (I), an intermolecular C—H⋯O hydrogen bond is present, whereas (II) does not exhibit any significant intermolecular interactions. However, in both compounds, an intramolecular N—H⋯N hydrogen bond forms a pseudo‐six‐membered ring, thus locking the molecular conformation and eliminating conformational flexibility. 相似文献
15.
Frdric Arod Manuel Gardon Philip Pattison Gervais Chapuis 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(5):o317-o320
N‐Salicylideneaniline (SA), C13H11NO, belongs to the large family of aromatic Schiff bases. It is of particular importance owing to its reversible photoreactivity. SA forms two photochromic polymorphs, both with two non‐coplanar benzene rings. In addition, we have recently discovered a planar polymorph, named the β‐polymorph, which will be discussed in a subsequent paper. We report here the structure of the α2‐polymorph in the orthorhombic crystal system. This compound exhibits a strong intramolecular O—H⋯N hydrogen bond and the dihedral angle between the two rings varies with temperature. 相似文献
16.
Svitlana V. Shishkina Irina S. Konovalova Sergiy M. Kovalenko Dmitriy V. Kravchenko Natalya D. Bunyatyan 《Acta Crystallographica. Section C, Structural Chemistry》2021,77(1):40-48
Being a close analogue of amflutizole, methyl 4‐amino‐3‐phenylisothiazole‐5‐carboxylate (C11H10N2O2S) was assumed to be capable of forming polymorphic structures. Noncentrosymmetric and centrosymmetric polymorphs have been obtained by crystallization from a series of more volatile solvents and from denser tetrachloromethane, respectively. Identical conformations of the molecule are found in both structures. The two polymorphs differ mainly in the intermolecular interactions formed by the amino group and in the type of stacking interactions between the π‐systems. The most effective method for revealing packing motifs in structures with intermolecular interactions of different types (hydrogen bonding, stacking, dispersion, etc.) is to study the pairwise interaction energies using quantum chemical calculations. Molecules form a column as the primary basic structural motif due to stacking interactions in both polymorphic structures under study. The character of a column (straight or zigzag) is determined by the orientations of the stacked molecules (in a `head‐to‐head' or `head‐to‐tail' manner). Columns bound by intermolecular N—H…O and N—H…N hydrogen bonds form a double column as the main structural motif in the noncentrosymmetric structure. Double columns in the noncentrosymmetric structure and columns in the centrosymmetric structure interact strongly within the ab crystallographic plane, forming a layer as a secondary basic structural motif. The noncentrosymmetric structure has a lower density and a lower (by 0.59 kJ mol?1) lattice energy, calculated using periodic calculations, compared to the centrosymmetric structure. 相似文献
17.
Marijana Juki Mario Cetina Jasna Vorkapi‐Fura
Amalija Golobi
Ante Nagl 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(7):o357-o359
Crystal structure analysis of the title compound, C13H12ClNO, reveals three crystallographically independent molecules in the asymmetric unit. The main conformational difference between these molecules is the orientation of the phenyl rings with respect to the pyrrole rings. The coplanar arrangement of the aldehyde groups attached to the pyrrole rings influences the pyrrole‐ring geometry. The C2—C3 and N1—C5 bonds are noticeably longer than the C4—C5 and N1—C2 bonds. Two independent molecules of the title compound form dimers via intermolecular C—H⃛O hydrogen bonds [D⃛A = 3.400 (3) Å and D—H⃛A = 157°]. The perpendicular orientation of the phenyl and pyrrole rings of one independent molecule and its symmetry‐related molecule allows C—H⃛π interactions, with an H⃛centroid distance of 2.85 Å and a C—H⃛π angle of 155°. The distances between the H atom and the pyrrole‐ring atoms indicate that the C—H bond points towards one of the bonds in the pyrrole ring. 相似文献
18.
Barbara Modec 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(4):340-343
Single crystals of a triclinic polymorphic form of mer‐μ‐oxalato‐bis[chloridotripyridinecobalt(II)] pyridine disolvate, [Co2(C2O4)Cl2(C5H5N)6]·2C5H5N, have been prepared by solvothermal methods. The structure and geometric parameters strongly resemble those of the previously reported monoclinic polymorph [Bolte (2006). Acta Cryst. E 62 , m597–m598]. In both polymorphic forms, the dinuclear complex molecules are located on a crystallographic centre of inversion, with the CoII cations in a distorted octahedral environment consisting of a chloride ligand, three pyridine ligands and a chelating bis‐bidentate oxalate ligand. This last serves as a bridging ligand between two CoII cations. The polymorphs differ in the mutual orientation of their pyridine ligands in the dinuclear molecules and in their intermolecular connectivity. In the triclinic polymorph, C—H...O, C—H...Cl, C—H...π and π–π interactions link the dinuclear molecules into a three‐dimensional structure. Pyridine solvent molecules are attached to this structure via weak interactions. 相似文献
19.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(1):52-56
1‐Benzoylthioureas contain both carbonyl and thiocarbonyl functional groups and are of interest for their biological activity, metal coordination ability and involvement in hydrogen‐bond formation. Two novel 1‐benzoylthiourea derivatives, namely 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea, C16H16N2O3S, (I), and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea, C11H14N2O2S, (II), have been synthesized and characterized. Compound (I) crystallizes in the space group P , while (II) crystallizes in the space group P 21/c . In both structures, intramolecular N—H…O hydrogen bonding is present. The resulting six‐membered pseudo‐rings are quasi‐aromatic and, in each case, interact with phenyl rings via stacking‐type interactions. C—H…O, C—H…S and C—H…π interactions are also present. In (I), there is one molecule in the asymmetric unit. Pairs of molecules are connected via two intermolecular N—H…S hydrogen bonds, forming centrosymmetric dimers. In (II), there are two symmetry‐independent molecules that differ mainly in the relative orientations of the phenyl rings with respect to the thiourea cores. Additional strong hydrogen‐bond donor and acceptor –OH groups participate in the formation of intermolecular N—H…O and O—H…S hydrogen bonds that join molecules into chains extending in the [001] direction. 相似文献
20.
Allison M. Mills Martin Lutz Gino P. F. Van Strijdonck Paul C. J. Kamer Piet W. N. M. Van Leeuwen Anthony L. Spek 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):m583-m585
The palladium(II) centre in the title compound, [PdCl2(C21H18N2OS)], is coordinated to the pyridyl N atom and to the thiazolidinone S atom of the 5‐benzyl‐3‐phenyl‐2‐(2‐pyridyl)thiazolidin‐4‐one ligand, resulting in a five‐membered chelate ring. Two cis‐chloro ligands complete the square‐planar coordination environment of the metal. Although the geometry at the Pd centre is essentially planar, the N—Pd—S bite angle of 85.20 (8)° causes deviations in the cis angles from the ideal value of 90°. Opposite enantiomers form one‐dimensional chains in the cell via a short S?O intermolecular interaction. 相似文献