共查询到20条相似文献,搜索用时 154 毫秒
1.
Samuel Robinson Jebas A. Sinthiya B. Ravindran Durai Nayagam Dieter Schollmeyer S. Alfred Cecil Raj 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(7):o361-o364
In the title compounds, 4‐aminopyridinium 4‐aminobenzoate dihydrate, C7H6NO2−·C5H7N2+·2H2O, (I), and 4‐aminopyridinium nicotinate, C5H7N2+·C6H4NO2−, (II), the aromatic N atoms of the 4‐aminopyridinium cations are protonated. In (I), the asymmetric unit is composed of two 4‐aminopyridinium cations, two 4‐aminobenzoate anions and four water molecules, and the compound crystallizes in a noncentrosymmetric space group. The two sets of independent molecules of (I) are related by a centre of symmetry which is not part of the space group. In (I), the protonated pyridinium ring H atoms are involved in bifurcated hydrogen bonding with carboxylate O atoms to form an R12(4) ring motif. The water molecules link the ions to form a two‐dimensional network along the (10) plane. In (II), an intramolecular bifurcated hydrogen bond generates an R12(4) ring motif and inter‐ion hydrogen bonding generates an R42(16) ring motif. The packing of adduct (II) is consolidated via N—H...O and N—H...N hydrogen bonds to form a two‐dimensional network along the (10) plane. 相似文献
2.
L. C. R. Andrade M. J. M. de Almeida J. A. Paixo F. M. Fernandes Roleira E. J. Tavares da Silva 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(6):o330-o331
The title compound, C21H28O4, has a 4‐acetoxy substituent positioned on the steroid α face. The six‐membered ring A assumes a conformation intermediate between 1α,2β‐half chair and 1α‐sofa. A long Csp3—Csp3 bond is observed in ring B and reproduced in quantum‐mechanical ab initio calculations of the isolated molecule using a molecular‐orbital Hartree–Fock method. Cohesion of the crystal can be attributed to van der Waals interactions and weak C—H...O hydrogen bonds. 相似文献
3.
Gopeswar Chaudhuri Madeleine Helliwell Nitya G. Kundu 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):740-741
In the title compound, C22H17Cl2NO3S, the molecule is a substituted 3,4‐dihydro‐2H‐1,4‐benzoxazine compound which has three phenyl rings which are essentially planar. The 3,4‐dihydro‐2H‐oxazine part of the molecule is fused to the benzo ring and has a half‐boat conformation; the dihedral angle between the planar part of the oxazine ring and the benzo ring is 10.2 (2)°. The (3‐chlorophenyl)methylidene substituent has a Z configuration in relation to the ring N atom of the oxazine moiety. Interestingly, the p‐toluenesulfonyl (p‐tosyl) substituent on the ring N atom protrudes away from the 3‐chlorophenyl substituent thus avoiding any steric interaction. 相似文献
4.
Anthony Linden C. Kuan Lee A. S. Muhammad Sofian 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1098-1100
At 160 K, the glucopyranosyl ring of the title compound, C20H28ClIO13, has a near‐ideal 4C1 conformation and the fructofuranosyl ring has a twist 4T3 conformation. The two hydroxy groups are involved in intra‐ and intermolecular hydrogen bonds, with the latter interactions linking the molecules into infinite one‐dimensional chains. The absolute configuration of the molecule has been determined. 相似文献
5.
G. Vasuki S. Thamotharan V. Parthasarathi K. Ramamurthi S. Dubey D. P. Jindal 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o598-o599
The title compound, C32H45N2O+·Br?·0.5H2O, has the outer two six‐membered rings in chair conformations, while the central ring is in an 8β,9α‐half‐chair conformation. The five‐membered ring of the steroid nucleus adopts a slightly deformed 14α‐envelope conformation. The pyridylmethylene moiety has an E configuration with respect to the hydroxyl group at position 17. The structure is stabilized by a network of O—H?Br‐type intermolecular hydrogen bonds. 相似文献
6.
Dan Jin De‐Chun Zhang 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(11):o657-o659
In the title compound, C15H13N2+·C24H20B−, the pyridyl ring of the cation makes a dihedral angle of 1.6° with the benzene ring. Each is rotated in the same direction with respect to the central –C—CH=CH—C– linkage, by 3.8 and 5.3°, respectively. The anions have a slightly distorted tetrahedral geometry. Molecular packing analysis was carried out using the packing energy portioning scheme in the program OPEC. Around each anion in the crystal structure there are eight anions, which interact with the central anion through C—H⋯π interactions. The cations are hydrogen bonded in a head‐to‐tail fashion, forming chains along [10]. 相似文献
7.
Benjamin J. Coe James A. Harris Thomas Gelbrich Michael B. Hursthouse 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1487-1489
The crystal structure of the dipolar chromophoric title compound, C20H20N3+·PF6?, is described. The phenylene and pyridyl rings are almost coplanar [dihedral angle 7.5 (2)°], but the phenyl substituent forms a dihedral angle of 56.6 (1)° with the pyridyl ring. The compound crystallizes in the non‐centrosymmetric space group Cc and is a likely candidate for the display of quadratic non‐linear optical effects. 相似文献
8.
Alexander Gutirrez Braulio Insuasty Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(1):o10-o12
The title compound, C16H14FNOS, crystallizes with Z′ = 2 in the space group P21/c. In one of the two independent molecules, the heterocyclic ring is effectively planar, but in the other molecule this ring adopts an envelope conformation. The molecules are weakly linked by two C—H...O hydrogen bonds to form C22(14) chains. Comparisons are made with some symmetrically substituted 2‐aryl‐3‐benzyl‐1,3‐thiazolidin‐4‐ones. 相似文献
9.
Ya‐Ling Liu Pei Zou Hao Wu Min‐Hao Xie Shi‐Neng Luo 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(9):o338-o340
The title compound, C16H24O10·0.11H2O, is a key intermediate in the synthesis of 2‐deoxy‐2‐[18F]fluoro‐d ‐glucose (18F‐FDG), which is the most widely used molecular‐imaging probe for positron emission tomography (PET). The crystal structure has two independent molecules (A and B) in the asymmetric unit, with closely comparable geometries. The pyranose ring adopts a 4C1 conformation [Cremer–Pople puckering parameters: Q = 0.553 (2) Å, θ = 16.2 (2)° and ϕ = 290.4 (8)° for molecule A, and Q = 0.529 (2) Å, θ =15.3 (3)° and ϕ = 268.2 (9)° for molecule B], and the dioxolane ring adopts an envelope conformation. The chiral centre in the dioxolane ring, introduced during the synthesis of the compound, has an R configuration, with the ethoxy group exo to the mannopyranose ring. The asymmetric unit also contains one water molecule with a refined site‐occupancy factor of 0.222 (8), which bridges between molecules A and B via O—H...O hydrogen bonds. 相似文献
10.
Dan Jin Zhao‐Fu Dai De‐Chun Zhang 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(2):o50-o52
In the title compound, C15H16NO+·C24H20B−, the pyridinium ring of the cation makes a dihedral angle of 4.3 (2)° with the benzene ring. Each is rotated in the same direction with respect to the central C—CH=CH—C linkage, by 10.0 (2) and 7.8 (2)°, respectively. The anions have a slightly distorted tetrahedral geometry. The most interesting feature of the structure is that the anions form a honeycomb‐like hexagonal structure down the b axis through C—H...π interactions. The hexagon is constructed from six BPh4− anions. The cations interact in a head‐to‐tail fashion along [010], forming chains, and pack antiparallel inside the above honeycomb‐like structure through C—H...π interactions. 相似文献
11.
Viktor Kettmann Jan Lokaj Viktor Milata Jozef Salo Mohamed Mahmoud Mohamed Hasan 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o365-o366
The title compound, C11H10N3+·Cl?·H2O, belongs to the N1‐methyl‐substituted imidazo[4,5‐f]quinoline family, in which the heterocyclic ring is protonated at the pyridine rather than at the imidazole N atom. The molecule as a whole is almost exactly planar. The molecular structure has been compared with that of the 2‐amino analogue described in the literature, and it was found that the extra amino group of the latter is involved in conjugation with the adjacent double bond, i.e. the conjugation does not extend over the entire heterocyclic system. The cation of the title compound forms a strong hydrogen bond with the Cl? anion and the anions are interconnected by the water solvent molecule. 相似文献
12.
Thaer Assaad Mwaffak Rukiah 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(11):o469-o472
The structure of the title benzovesamicol analogue, C21H27N3O2, an important compound for the diagnosis of Alzheimer's disease, has been determined by X‐ray powder diffraction. The title compound was firstly synthesized and characterized by spectroscopic methods (FT–IR, and 13C and 1H NMR). The compound is a racemic mixture of enantiomers which crystallizes in the monoclinic system in a centrosymmetric space group (P21/c). Crystallography, in particular powder X‐ray diffraction, was pivotal in revealing that the enantio‐resolution did not succeed. The piperazine ring is in a chair conformation, while the cyclohexene ring assumes a half‐chair conformation. The crystal packing is dominated by intermolecular O—H...N hydrogen bonding which links molecules along the c direction. 相似文献
13.
Jonathan C. Parrish Rudong Shan Edward E. Knaus Michael N. G. James 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):107-109
This analysis establishes the rotameric orientation of the pyridyl‐ring N atom of the title compound, C17H21N3O4·0.5C6H6, as antiperiplanar (ap) to the 1,4‐dihydropyridine H‐4, the absence of an intramolecular hydrogen bond between the 1,4‐dihydropyridine NH and the pyridyl‐N atom, and the unusual planarity of the 1,4‐dihydropyridine ring. 相似文献
14.
Vitor F. Ferreira Antonio V. Pinto Maria C. R. F. Pinto Milton N. da Silva Janet M. S. Skakle Maria C. B. V. de Souza Solange M. S. V. Wardell 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(9):o560-o562
The central six‐membered ring in the title compound, C16H16O3, is almost planar (and almost coplanar with the aromatic ring), despite one of its C atoms being formally sp3 hybridized. The planarity is a consequence of the C atom at the centre of the spirocyclic system also being part of the three‐membered epoxide ring. The molecules are linked by π–π and C—H?π interactions. 相似文献
15.
Dipak K. Hazra Rajarshi Chatterjee Mahammad Ali Monika Mukherjee 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(4):o190-o193
The molecular structure of the title salt, C11H17N4+·H2PO4−, has been determined from single‐crystal X‐ray analysis and compared with the structure calculated by density functional theory (DFT) at the BLYP level. The crystal packing in the title compound is stabilized primarily by intermolecular N—H...O, O—H...N and O—H...O hydrogen bonds and π–π stacking interactions, and thus a three‐dimensional supramolecular honeycomb network consisting of R42(10), R44(14) and R44(24) ring motifs is established. The HOMO–LUMO energy gap (1.338 eV; HOMO is the highest occupied molecular orbital and LUMO is the lowest unoccupied molecular orbital) indicates a high chemical reactivity for the title compound. 相似文献
16.
Thiruneelakantan Lakshmanan Desikan Sriram Duraikannu Loganathan 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):825-826
The crystal structure of the title compound, C14H25NO11·2H2O, has been determined. The glucose and galactose residues are in a 4C1 conformation. The N‐acetyl group has a Z‐anti conformation. 相似文献
17.
Anthony Linden Andreas Gebert Heinz Heimgartner 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):764-766
The tetrathiane ring of the title compound, C26H16S4, has a chair conformation and the molecule has approximate C2 symmetry. Each of the two fluorene ring systems is virtually planar, with the ring planes intersecting at an angle of 67.58 (5)°. This novel compound has been formed as a side product from the treatment of 9H‐fluorene‐9‐thione with methyl N‐[(benzylidene)phenyl]glycinate in the presence of LiBr and 1,6‐diazabicyclo[5.4.0]undecane. 相似文献
18.
Mustafa Odabaolu idem Albayrak Orhan Büyükgüngr 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(4):o240-o242
Molecules of the title compound, C8H9NO2, are linked into sheets by a combination of C—H·N, O—H·N and O—H·O hydrogen bonds and C—H·π interactions. The hydrogen bonds are arranged as described by the graph‐set ring notations R22(7) and R33(5), and a C8 chain motif. There are two planar symmetry‐independent molecules in the asymmetric unit, with a dihedral angle of 19.24 (5)° between their least‐squares mean planes. 相似文献
19.
G. Vasuki V. Parthasarathi K. Ramamurthi D. P. Jindal S. Dubey 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o162-o163
The title compound, C27H29NO2, has the outer six‐membered ring in a sofa conformation, while the central rings are in chair conformations. The five‐membered ring adopts a slightly distorted 13β,14α‐half‐chair conformation. The cyanobenzylidene moiety has an E configuration with respect to the carbonyl group at position 17. 相似文献
20.
Gary S. Nichol Francis N. Murigi Eugene A. Mash 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(6):o302-o304
Synchrotron radiation was used to study the structure of the title compound, C20H19BrN2O3·C3H7NO, which was obtained as fine fragile needle‐shaped crystals by recrystallization from dimethylformamide (DMF), one molecule of which is incorporated per asymmetric unit into the crystal. The compound adopts a compact closed conformation with the orientation of the benzyl group such that the aryl ring is positioned over the piperazinedione ring, resulting in a Cspiro...Ctrans—C—CPh pseudo‐torsion angle of −3.3 (3)°. The five‐membered ring is present in an expected envelope conformation and the six‐membered piperazinedione ring adopts a less puckered boat‐like conformation. Reciprocal amide‐to‐amide hydrogen bonding between adjacent piperazinedione rings and C—H...O interactions involving DMF molecules propagate in the crystal as a thick ribbon in the a‐axis direction. 相似文献