共查询到20条相似文献,搜索用时 10 毫秒
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The idea that hydrogen bond cooperativity is responsible for the structure and reactivity of carbohydrates is examined. Density functional theory and gauge‐including atomic orbital calculations on the known conformers of the α and β anomers of d ‐glucopyranose in the gas phase are used to compute proton NMR chemical shifts and interatomic distances, which are taken as criteria for probing intramolecular interactions. Atom–atom interaction energies are calculated by the interacting quantum atoms approach in the framework of the quantum theory of atoms in molecules. Association of OH1 in the counterclockwise conformers with a strong acceptor, pyridine, is accompanied by cooperative participation from OH2, but there is no significant change in the bonding of the two following 1,2‐diol motifs. The OH6 ... O5 (G?g+/cc/t and G+g?/cc/t conformers) or OH6 ... O4 (Tg+/cc/t conformer) distance is reduced, and the OH6 proton is slightly deshielded. In the latter case, this shortening and the associated increase in the OH6–O4 interaction energy may be interpreted as a small cooperative effect, but intermolecular interaction energies are practically the same for all three conformers. In most of the pyridine complexes, one ortho proton interacts with the endocyclic oxygen O5. Analogous results are obtained when the clockwise conformer, G?g+/cl/g?, detected for the α anomer, and a hypothetical conformer, Tt/cl/g?, are complexed with pyridine through OH6. Generally, the cooperative effect does not go beyond the first two OH groups of a chain. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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K. Manoj S. Devaraj R. G. Gonnade M. M. Bhadbhade M. S. Shashidhar 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(11):o628-o630
The centrosymmetric O—H⋯O‐bonded head‐to‐head dimers of the title compound, C21H22O6, are linked together via bifurcated C—H⋯O interactions along the a axis and via favourable C—H⋯π interactions along the b axis in the crystal structure. 相似文献
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Thomas Steiner Antoine M. M. Schreurs Martin Lutz Jan Kroon 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):577-579
The title compounds contain very short intramolecular hydrogen bonds of the type C—O—H?O—N. The O?O distances are 2.425 (2) Å in picolinic acid N‐oxide (2‐carboxypyridine N‐oxide), C6H5NO3, (I), and 2.435 (2) Å in quinaldic acid N‐oxide (2‐carboxyquinoline N‐oxide), C10H7NO3, (II). In (II), this is associated with slight molecular distortion from planarity, while in (I), such an effect cannot be observed because the molecule crystallizes on a mirror plane. 相似文献
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T. Vijay T. Narasimhamurthy H. S. Yathirajan R. S. Rathore P. Nagaraja 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(1):o36-o38
In the crystal structure of the title salt, C7H7Cl2N2O2+·Cl−, the chloride anions participate in extensive hydrogen bonding with the aminium cations and indirectly link the molecules through multiple N+—H⋯Cl− salt bridges. There are two independent molecules in the asymmetric unit, related by a pseudo‐inversion center. The direct intermolecular coupling is established by C—H⋯O, C—H⋯Cl and C—Cl⋯Cl− interactions. A rare three‐center (donor bifurcated) C—H⋯(O,O) hydrogen bond is observed between the methylene and nitro groups, with a side‐on intramolecular component of closed‐ring type and a head‐on intermolecular component. 相似文献
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Christopher Glidewell John N. Low Antonio Quesada Manuel Nogueras Adolfo Snchez 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):o425-o427
In the title compound, C22H23N5O4, the molecules are linked into chains by a three‐centre N—H?(N,O) hydrogen bond, reinforced by a two‐centre C—H?O hydrogen bond, and the chains are further linked into sheets by a combination of C—H?O and C—H?π(arene) hydrogen bonds. 相似文献
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Veysel T. Yilmaz Canan Kazak Cumhur Kirilmis Murat Koca Frank W. Heinemann 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(7):o438-o441
The molecules of 2‐benzoyl‐1‐benzofuran, C15H10O2, (I), interact through double C—H⋯O hydrogen bonds, forming dimers that are further linked by C—H⋯O, C—H⋯π and π–π interactions, resulting in a three‐dimensional supramolecular network. The dihedral angle between the benzoyl and benzofuran fragments in (I) is 46.15 (3)°. The molecules of bis(5‐bromo‐1‐benzofuran‐2‐yl) ketone, C17H8Br2O3, (II), exhibit C2 symmetry, with the carbonyl group (C=O) lying along the twofold rotation axis, and are linked by a combination of C—H⋯O and C—H⋯π interactions and Br⋯Br contacts to form sheets. The stability of the molecular packing in 3‐mesityl‐3‐methylcyclobutyl 3‐methylnaphtho[1,2‐b]furan‐2‐yl ketone, C28H28O2, (III), arises from C—H⋯π and π–π stacking interactions. The fused naphthofuran moiety in (III) is essentially planar and makes a dihedral angle of 81.61 (3)° with the mean plane of the trimethylbenzene ring. 相似文献
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Christopher Glidewell George Ferguson Richard M. Gregson Alan J. Lough 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):174-176
The title compound, [Ni(C7H5O3)2(C10H24N4)], contains octahedral NiII in a centrosymmetric trans configuration with Ni—N distances of 2.0637 (17) and 2.0699 (16) Å and an Ni—O distance of 2.1100 (14) Å. The molecules are linked by a single type of O—H?O hydrogen bond [O?O 2.618 (2) Å and O—H?O 161°] into two‐dimensional sheets; a singletype of N—H?O hydrogen bond [N?O 2.991 (2) Å and N—H?O 139°] links these sheets into a three‐dimensional framework. 相似文献
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Antonio Quesada John N. Low Manuel Melguizo Manuel Nogueras Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o355-o358
The molecules of the title compound, C18H16N4O3, exhibit a very polarized molecular–electronic structure. The molecules are linked into chains by a combination of an asymmetric three‐centre N—H?(N,O) hydrogen bond [H?N 2.19, H?O 2.54, N?N 3.041 (4) and N?O 2.977 (4) Å, and N—H?N 168, N—H?O 112 and N?H?O 67°] and an N—H?π(arene) interaction [H?Cg 2.67 Å, N?Cg 3.496 (4) Å and N—H?Cg 163°; Cg is a benzyl ring centroid]. 相似文献
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Li‐Ping Lu Shu‐Qin Yao Miao‐Li Zhu 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):m220-m222
In the title compound, [Cu(C14H9NO3)(H2O)2], which crystallizes with Z = 18 in the space group R, pairs of complexes are linked into dimers by three O—H⋯O hydrogen bonds. Strong O—H⋯O hydrogen bonds link the dimers into one‐dimensional chains that further assemble into tubes through π–π and C—H⋯π interactions. 相似文献
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James L. Wardell John Nicolson Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):679-681
In the title compound, (4‐O2NC6H4)2S2 or C12H8N2O4S2, the molecules lie across twofold rotation axes. A single type of C—H?O hydrogen bond, with C?O = 3.394 (3) Å and C—H?O = 158°, links the molecules into continuous two‐dimensional sheets built from a single type of R44(44) ring. These sheets are linked by aromatic π?π stacking interactions to form a continuous three‐dimensional framework. 相似文献
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Swastik Mondal Monika Mukherjee Arnab Roy Debabrata Mukherjee Madeleine Helliwell 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o474-o476
In the title compound, C13H22O3, the asymmetric unit has two independent molecules linked by a strong O—H?O hydrogen bond. The cyclohexane ring is trans fused to the cyclopentane ring bridged through an ethyl moiety. The hydroxyl groups act as donors as well as acceptors, resulting in an extensive two‐dimensional hydrogen‐bonded network in the (011) plane. Intermolecular O—H?O bonds between centrosymmetrically related molecules form a four‐membered supramolecular assembly, leading to infinite chains parallel to the [01] direction, crosslinked in the [100] direction. 相似文献
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Katharine F. Bowes George Ferguson Alan J. Lough Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):o464-o466
In the title compound, C13H16N22+·2C2H4O5P−, the cation lies across a twofold rotation axis in space group Fdd2. The anions are linked into molecular ladders by two O—H⃛O hydrogen bonds [H⃛O = 1.73 and 1.77 Å, O⃛O = 2.538 (2) and 2.598 (3) Å, and O—H⃛O = 160 and 170°], these ladders are linked into sheets by a single type of N—H⃛O hydrogen bond [H⃛O = 1.75 Å, N⃛O = 2.624 (3) Å and N—H⃛O = 171°] and the sheets are linked into a three‐dimensional framework by a single type of C—H⃛O hydrogen bond [H⃛O = 2.48 Å, C⃛O = 3.419 (4) Å and C—H⃛O = 167°]. 相似文献
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Jaromír Marek Kamila Lunerov Jaromír Touek Vclav Suchý Radek Marek 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):o386-o389
The crystal structures of 2′,4′‐dihydroxy‐3‐methoxy‐α,β‐dihydrochalcone, C16H16O4, and 2′,4‐dihydroxy‐α,β‐dihydrochalcone, C15H14O3, have been determined. In both compounds, the structure consists of two nearly planar six‐membered aromatic rings connected by a propanal chain, which is bent in the methoxy compound and almost straight in the other compound. In the crystal structures, the molecular units of both compounds are linked by O—H⋯O hydrogen bonds to form infinite one‐dimensional chains. Hydrogen bonds and C—H⋯O contacts in the crystal structures were studied by topological analysis of charge density based on Hartree–Fock calculations. Almost all of the investigated C—H⋯O contacts should be characterized as weak hydrogen bonds. 相似文献
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Shu‐Qin Yao Xiao‐Li Gao Miao‐Li Zhu Li‐Ping Lu 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):m183-m185
In the title compound, [Cd(C14H10NO3)2(H2O)2], which crystallizes with Z = 4 in the space group C2c, the Cd atom is located on a twofold rotation axis and coordinated by six O atoms from two water molecules and two carboxylate groups of two planar 4‐(2‐hydroxybenzylideneamino)benzoate ligands, with a dihedral angle of 85.6 (1)° between them. Strong O—H⋯O hydrogen bonding in the coordination sphere, together with π–π stacking interactions, assemble the molecules into two‐dimensional layers. 相似文献
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Choudhury M. Zakaria George Ferguson Alan J. Lough Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):687-689
In the title compound, 2[Fe(C5H5)(C6H5O2)]·C6H12N2, the molecular components are linked into finite three‐component aggregates by strong O—H?N hydrogen bonds [O?N 2.578 (4) and 2.604 (5) Å; O—H?N 170 (5) and 174 (6)°]; these aggregates are further linked by C—H?O hydrogen bonds [C?O 3.327 (5)–3.401 (5) Å; C—H?O 149–157°] into continuous sheets in the form of (6,3) nets. 相似文献