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Hydrogen-bonded Motifs (hydrogen-bonded + motif)
Selected AbstractsBis[2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium] dl -malateACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009S. Franklin Racemic malic acid and trimethoprim [5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine] form a 1:2 salt (monoclinic, P21/c), 2C14H19N4O3+·C4H4O52,, in which the malate component is disordered across a centre of inversion. The crystal structure of the salt consists of protonated trimethoprim residues and a malate dianion. The carboxylate group of the malate ion interacts with the trimethoprim cation in a linear fashion through pairs of N,H...O hydrogen bonds to form a cyclic hydrogen-bonded motif. This is similar to the carboxylate,trimethoprim cation interaction observed earlier in the complex of dihydrofolate reductase with trimethoprim. The structure of the salt of trimethoprim with racemic dl -malic acid reported here is the first of its kind. The present study investigates the conformations and the hydrogen-bonding interactions, which are very important for biological functions. The pyrimidine plane makes a dihedral angle of 78.08,(7)° with the benzene ring of the trimethoprim cation. The cyclic hydrogen-bonded motif observed in this structure is self-organized, leading to novel types of hydrogen-bonding motifs in supramolecular patterns. [source] Two- and Three-Dimensional Hydrogen-Bonded Networks Built from 1,3,5-[(HO)2(O)P]3C6H3 and 4-(Dimethylamino)pyridineEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2004Michael Mehring Abstract Crystallisation of 3,5-bis(phosphonophenyl)phosphonic acid, 1,3,5-[(HO)2(O)P]3C6H3, from MeOH/H2O in the presence of 4-(dimethylamino)pyridine, 4-(Me2N)C5H4N, gave [1-{(HO)2(O)P}-3,5-{(HO)(O)2P}2C6H3]2,[{4-(Me2N)C5H4NH}+]2 (2) and [1,3-{(HO)2(O)P}2 -5-{(HO)(O)2P}C6H3],[4-(Me2N)C5H4NH]+ (3). Single-crystal X-ray diffraction analyses revealed a two- and a three-dimensional hydrogen-bonded network for compounds 2 and 3, respectively. Compound 2 is composed of layers which are formed by hydrogen-bonded motifs of the type R2,2(8) and R4,4(16). These motifs are connected within the layer by additional hydrogen bonds and the benzene spacer. The cation [4-(Me2N)C5H4NH]+ is located between the layers and determines the interlayer separation of approximately 6.5 Ĺ. In compound 3 a layered network of the hydrogen-bonded building units R2,3(10) was observed. These units are interconnected by four additional hydrogen bonds within the network. The benzene spacer links the adjacent layers to give a three-dimensional structure. Within this network, channels with internal dimensions of ca. 8.5 × 11.3 Ĺ2 which are occupied by the [4-(Me2N)C5H4NH]+ cations were observed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Supramolecular structure of 1H -pyrazoles in the solid state: a crystallographic and ab initio studyACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2000Concepción Foces-Foces The secondary structure of 1H -unsubstituted pyrazole derivatives bearing only one hydrogen donor group and one or more acceptor groups has been analyzed in terms of some descriptors representing the substituents at C3 and C5. The substituent at C4 appears to affect mainly the tertiary or quaternary structure of these compounds. The proposed semi-quantitative model, which explains most hydrogen-bonded motifs as a combination of the effects of substituents at C3 and C5, has also been examined as a function of the steric and polarizability effects of these substituents represented by molar refractivity. The model also applies to other five-membered rings (1,2,4-triazoles, 1,2,4-diazaphospholes and 1,2,4-diazaarsoles). Furthermore, ab initio calculations at RHF/6-31G* have been performed to discover the relative stability of three of the four hydrogen-bond patterns displayed by several symmetrical pyrazoles (dimers, trimers, tetramers). The fourth motif, catemers, has only been discussed geometrically. [source] Azetidine, pyrrolidine and hexamethyleneimine at 170,KACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2008Andrew D. Bond The crystal structures of the cyclic amines azetidine (C3H7N), pyrrolidine (C4H9N) and hexamethyleneimine (homopiperidine, C6H13N), of the series (CH2)nNH, with n = 3, 4 and 6, respectively, have been determined at 170,K, following in situ crystallization from the melt. These structures provide crystallographic data to complete the homologous series of cyclic amines (CH2)nNH, for n = 2,6. Azetidine and pyrrolidine contain chains propagating along 21 screw axes, in which the molecules are linked by co-operative N,H...N hydrogen bonds. Azetidine has two molecules in its asymmetric unit, while pyrrolidine has only one. Hexamethyleneimine contains tetrameric hydrogen-bonded rings formed about crystallographic inversion centres, with two molecules in its asymmetric unit. The observation of crystallographically distinct molecules in the hydrogen-bonded chains of azetidine and cyclic hydrogen-bonded motifs in hexamethyleneimine is consistent with expectations derived from comparison with monoalcohols forming chains or rings by co-operative O,H...O hydrogen bonds. The next member of the cyclic amine series, heptamethyleneimine, forms a cubic plastic phase on cooling from the melt. [source] | ||||||||||