Self-assembly of NH-pyrazoles via intermolecular N—H...N hydrogen bonds

1999 ◽  
Vol 55 (6) ◽  
pp. 985-993 ◽  
Author(s):  
Valerio Bertolasi ◽  
Paola Gilli ◽  
Valeria Ferretti ◽  
Gastone Gilli ◽  
Cristina Fernàndez-Castaño
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Pyrazole Ring ◽  
Mean Value ◽  
Hydrogen Bond Interaction ◽  
Proton Disorder ◽  
Resonance Assisted Hydrogen Bond ◽  
Proton Sponges ◽  
Substituted Pyrazoles

The crystal structures of two NH-pyrazole derivatives forming intermolecular N—H...N hydrogen bonds are reported: 5-methyl-4-(3-methylpyrazol-5-yl)pyrazol-3-ol, C8H10N4O (P1), and 3-methyl-5-dihydro-1H-naphtho[1,2-d]pyrazole hemihydrochloride, C12H12N2.-C12H13N_{2}^{+}.Cl− (P2). 26 other structures are surveyed in order to obtain a deeper insight into the ways NH-pyrazoles self-assemble by means of intermolecular N—H...N hydrogen bonds in molecular crystals. A limited number of compounds form chains or dimers via homonuclear N+—H...N positive-charge-assisted hydrogen bonds, typical of proton sponges, which can be remarkably short [e.g. N...N 2.714 (3), N—H 1.09 (3), H...N 1.63 (3) Å, N—H...N 169 (3)° in (P2)]. Most pyrazoles, however, pack via neutral N—H...N bonds which are formally assisted by resonance (resonance-assisted hydrogen bond, RAHB) through the ...N=C—C=C—NH... iminoenamine fragment, contained in the ring, giving rise to dimers, trimers, tetramers and infinite chains of pyrazole molecules. Surprisingly, the resonance does not appear to shorten the N—H...N bond with respect to the accepted mean value N...N 2.97 (10) Å for non-resonant N—H...N bonds. It is shown that this is due to the internal π-delocalization of the pyrazole ring, which can be hardly increased by the hydrogen-bond interaction, except in symmetrically 3,5-substituted pyrazoles which display N...N distances as short as 2.82 Å, identical C—C and C—N distances in the two halves of the pyrazole molecule, and typical phenomena of N—H...N dynamical proton disorder, detectable by 15N-CP/MAS solid-state NMR.

Synthesis and Structural Characterisation of New Bifunctional o-Hydroxyacetophenones – Potential Linker Molecules for Coordinative Framework Construction

2013 ◽  
Vol 68 (3) ◽  
pp. 214-222 ◽  
Author(s):  
Jörg Hübscher ◽  
Michael Günthel ◽  
Robert Rosin ◽  
Wilhelm Seichter ◽  
Florian Mertens ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
X Ray ◽  
Structural Characterisation ◽  
Crystallographic Study ◽  
Copper Coordination ◽  
Resonance Assisted Hydrogen Bond ◽  
Intramolecular Hydrogen ◽  
Fitting In ◽  
Linker Molecules

Two new linker-type molecules 1a and 1b composed of o-hydroxyacetophenone coordinative groups attached to linear ethynylene or 1,4-phenylenediethynylene spacer units have been synthesised and structurally characterised. An X-ray crystallographic study for both compounds has shown structures with strong intramolecular hydrogen bonds fitting in the model of ‘Intramolecular Resonance Assisted Hydrogen Bond (IRHAB)’. Initial coordination experiments with Cu(II) were performed and the resulting materials characterised by PXRD. The similarity of the copper coordination between these compounds and copper(II) acetylacetonate complexes was demonstrated by XPS measurements. Based on the evidence of these studies, and on elemental analysis, the formation of the corresponding coordination polymers comprising Cu(II) and the linkers has been proposed

scholarly journals Crystal structure of (E)-4-{[2-(2,4-dinitrophenyl)hydrazin-1-ylidene]methyl}-3-methyl-1-phenyl-5-(1H-pyrrol-1-yl)-1H-pyrazole

2014 ◽  
Vol 70 (12) ◽  
pp. o1246-o1247 ◽  
Author(s):  
Joel T. Mague ◽  
Shaaban K. Mohamed ◽  
Mehmet Akkurt ◽  
Hussein M. S. El-Kashef ◽  
Mustafa R. Albayati
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Pyrazole Ring ◽  
Dihedral Angles ◽  
Extended Conformation ◽  
Compound C ◽  
Benzene Rings

The title compound, C21H17N7O4, is in an `extended' conformation aided by an intramolecular N—H...O hydrogen bond. The pyrazole ring makes dihedral angles of 29.17 (6), 65.47 (4) and 9.91 (7)°, respectively, with the phenyl, pyrrole and benzene rings. In the crystal, molecules are connected by pairs of N—H...O and C—H...O hydrogen bonds, forming inversion dimers which associate into ribbons running along thebaxis through complementary C—H...O interactions.

Excess volumes of an alcohol + 1,2-dichloroethane

1981 ◽  
Vol 59 (14) ◽  
pp. 2210-2211 ◽  
Author(s):  
Nettem V. Choudary ◽  
Puligundla R. Naidu
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Binary Mixtures ◽  
Excess Volumes ◽  
Hydrogen Bond Interaction ◽  
Bond Interaction ◽  
Break Up ◽  
The Difference

Excess volumes for binary mixtures of 1,2-dichloroethane with n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, and n-octanol have been determined at 303.15 K. VE is positive over the whole range of composition in all the mixtures. However, it is noticed that the positive values of VE of mixtures of 1,2-dichloroethane with n-hexanol, n-heptanol, and n-octanol differ from those for the mixtures of 1,2-dichloroethane with corresponding alkanes. The difference has been explained in terms of the break up of hydrogen bonds, interstitial accommodation of 1,2-dichloroethane in alcohol aggregates, and possible hydrogen bond interaction of the type Cl … H—O between unlike molecules.

scholarly journals Crystal structure of 6-amino-4-(3-bromo-4-methoxyphenyl)-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile dimethyl sulfoxide monosolvate

2015 ◽  
Vol 71 (7) ◽  
pp. o453-o454 ◽  
Author(s):  
Sammer Yousuf ◽  
Huma Bano ◽  
Munira Taj Muhammad ◽  
Khalid Mohammed Khan
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Dimethyl Sulfoxide ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Pyrazole Ring ◽  
Ring System ◽  
The Mean

In the pyrazole molecule of the title solvate, C15H13BrN4O2·C2H6OS, the dihedral angle between the benzene ring and the mean plane of the dihydropyrano[2,3-c]pyrazole ring system [r.m.s deviation = 0.031 (2) Å] is 86.71 (14)°. In the crystal, the pyrazole molecules are linked by N—H...N hydrogen bonds, forming a layer parallel to (10-1). The pyrazole and dimethyl sulfoxide molecules are connected by an N—H...O hydrogen bond.

Molecular dynamics simulations of N-methylacetamide (NMA) in water by the ABEEM/MM model

2009 ◽  
Vol 87 (12) ◽  
pp. 1738-1746 ◽  
Author(s):  
Ping Qian ◽  
Li-Nan Lu ◽  
Zhong-Zhi Yang
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Potential Model ◽  
Lone Pair ◽  
Static Properties ◽  
Range Interaction ◽  
Hydrogen Bond Interaction ◽  
Lone Pair Electron ◽  
Dynamics Simulations

The N-methylacetamide (NMA) is a very interesting kind of compound and often serves as a model of the peptide bond. The interaction between NMA and water provides a convenient prototype for the solvation of peptides in aqueous solutions. We have carried out molecular dynamics (MD) simulations of a NMA molecule in water under 1 atm and 298 K. The simulations make use of the newly developed NMA–water fluctuating charge ABEEM/MM potential model ( Yang, Z. Z.; Qian, P. J. Chem. Phys. 2006, 125, 064311 ), which is based on the combination of the atom-bond electronegativity equalization method (ABEEM) and molecular mechanics (MM). This model has been successfully applied to NMA–water gas clusters, NMA(H2O)n (n = 1–6), and accurately reproduced many static properties. For the NMA–water ABEEM/MM potential model, two characters must be emphasized in the simulations. Firstly, the model allows the charges in system to fluctuate, responding to the ambient environment. Secondly, for two major types of intermolecular hydrogen bonds, which are the hydrogen bond forming between the lone-pair electron on amide oxygen and the water hydrogen, and the one forming between the lone-pair electron on water oxygen and the amide hydrogen, we take special treatments in describing the electrostatic interaction by the use of the parameters klpO=,H and klpO–,HN–, respectively, which explicitly describe the short-range interaction of hydrogen bonds in the hydrogen bond interaction region. All sorts of properties have been studied in detail, such as, radial distribution function, energy distribution, ABEEM charge distribution and dipole moment, and so on. These simulation results show that the ABEEM/MM-based NMA–water potential model appears to be robust, giving the solution properties in excellent agreement with other dynamics simulations on similar systems.

scholarly journals 5-Methyl-1,3-diphenyl-N-(5-phenyl-1,3,4-thiadiazol-2-yl)-1H-pyrazole-4-carboxamide

2013 ◽  
Vol 69 (12) ◽  
pp. o1736-o1736
Author(s):  
Chandra ◽  
S. S. Mahesh ◽  
N. Srikantamurthy ◽  
K. B. Umesha ◽  
K. Palani ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Phenyl Group ◽  
Pyrazole Ring ◽  
Dihedral Angles ◽  
Asymmetric Unit ◽  
Compound C ◽  
Thiadiazole Ring ◽  
Dimer Linkage

The asymmetric unit of the title compound C25H19N5OS, contains two molecules,AandB. In moleculeA, the dihedral angles between the pyrazole ring and the C-bound phenyl group, the N-bound phenyl group and the thiadiazole ring are 32.30 (14), 52.25 (14) and 34.94 (12)°, respectively. The corresponding angles in moleculeBare 33.32 (14), 50.67 (15), and 70.30 (12)°, respectively. In the crystal, theAandBmolecules are linked by pairs of N—H...N hydrogen bonds, generatingR22(8) loops. This dimer linkage is reinforced by two C—H...O hydrogen bonds and one C—H...N hydrogen bond.

scholarly journals Interactions of Aggregating Peptides Probed by IR-UV Action Spectroscopy

2018 ◽  
Author(s):  
Sjors Bakels ◽  
E.M. Meijer ◽  
Mart Greuell ◽  
Sebastiaan Porskamp ◽  
George Rouwhorst ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Self Assembly ◽  
Intermolecular Hydrogen Bond ◽  
Beta Sheet ◽  
Dispersion Interactions ◽  
Intramolecular Hydrogen Bonds ◽  
Action Spectroscopy ◽  
Hydrogen Bond Interactions ◽  
Intramolecular Hydrogen

Peptide aggregation, the self-assembly of peptides into structured beta-sheet fibril structures, is driven by a combination of intra- and intermolecular interactions. Here, the interplay between intramolecular and formed inter-sheet hydrogen bonds and the effect of dispersion interactions on the formation of neutral, isolated, peptide dimers is studied by infrared action spectroscopy. Therefore, four different homo- and hetereogeneous dimers formed from three different alanine-based model peptides have been studied under controlled and isolated conditions. The peptides differ from one another in the presence and location of a UV chromophore containing cap on either the C- or N-terminus. Conformations of the monomers of the peptides direct the final dimer structure: strongly hydrogen bonded or folded structures result in weakly bound dimers. Here the intramolecular hydrogen bonds are favored over new intermolecular hydrogen bond interactions. In contrast, linearly folded monomers are the ideal template to form parallel beta-sheet type structures. The weak intramolecular hydrogen bonds present in the linear monomers are replaced by the stronger inter-sheet hydrogen bond interactions. The influence of π-π disperion interactions on the structure of the dimer is minimal, the phenyl rings have the tendency to fold away from the peptide backbone to favour intermolecular hydrogen bond interactions. Quantum chemical calculations confirm our experimental observations.

Supramolecular Structure in the Cocrystal of 3, 5-Bispyridyl-1-H-1, 2, 4-Triazole and 4,4-Oxybis(Benzoic Acid)

2013 ◽  
Vol 781-784 ◽  
pp. 531-535
Author(s):  
Ting Li ◽  
Bing Li ◽  
Xiao Yan Chen ◽  
Jun Mei Wang ◽  
Lin Sun ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Benzoic Acid ◽  
Self Assembly ◽  
Cobalt Acetate ◽  
Intermolecular Hydrogen Bonds ◽  
Hydrogen Bond Interaction ◽  
Monoclinic System ◽  
One Dimensional ◽  
Carboxylate Groups ◽  
The One

A new cocrystal (3,4-Hbpt)-(H2oba) (3,4-Hbpt =3-(3-pyridyl)-5-(4-pyridyl)- 1-H-1,2,4-triazole and H2oba=4,4-oxybis (benzoic acid)), was prepared via self-assembly in the presence of cobalt acetate as template by hydrothermal reactions. The title complex was characterized by single-crystal X-ray diffraction, elemental analysis and IR spectroscopy. Structural analysis reveals that the complex belongs to monoclinic system, space group P21/c. The two carboxylate groups from H2oba are not deprotonated and form two kinds of strong intermolecular hydrogen bonds with 3,4-Hbpt, which linking the molecules into one-dimensional chains. Furthermore, the one-dimensional chains are connected by the hydrogen bond interaction to form two-dimensional lamellar structures. Intermolecular hydrogen bonds may be effective in the stabilization of the crystal structure.

2-Ethyl-1-[5-(4-methylphenyl)pyrazol-3-yl]-3-(thiophene-2-carbonyl)isothiourea: molecular ribbons containing three types of hydrogen-bonded ring

2014 ◽  
Vol 70 (11) ◽  
pp. 1064-1068
Author(s):  
Edison Castro ◽  
Henry Insuasty ◽  
Braulio Insuasty ◽  
Justo Cobo ◽  
Christopher Glidewell
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Microwave Irradiation ◽  
Title Compound ◽  
Pyrazole Ring ◽  
Solvent Free ◽  
Compound C ◽  
Solvent Free Conditions ◽  
Hydrogen Bonded

The title compound, C18H18N4OS2, was prepared by reaction ofS,S-diethyl 2-thenoylimidodithiocarbonate with 5-amino-3-(4-methylphenyl)-1H-pyrazole using microwave irradiation under solvent-free conditions. In the molecule, the thiophene unit is disordered over two sets of atomic sites, with occupancies of 0.814 (4) and 0.186 (4), and the bonded distances provide evidence for polarization in the acylthiourea fragment and for aromatic type delocalization in the pyrazole ring. An intramolecular N—H...O hydrogen bond is present, forming anS(6) motif, and molecules are linked by N—H...O and N—H...N hydrogen bonds to form a ribbon in which centrosymmetricR22(4) rings, built from N—H...O hydrogen bonds and flanked by inversion-related pairs ofS(6) rings, alternate with centrosymmetricR22(6) rings built from N—H...N hydrogen bonds.

scholarly journals Hydrogen-bonded chains in 3,5-bis(4-fluorophenyl)-1-phenyl-1H-pyrazole and complex hydrogen-bonded sheets in (5RS,6SR)-6-(4-fluorobenzoyl)-5-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5,6-dihydro-4H-1,3,4-oxadiazineN,N-dimethylformamide monosolvate

2014 ◽  
Vol 70 (9) ◽  
pp. 867-871 ◽  
Author(s):  
Seranthimata Samshuddin ◽  
Jerry P. Jasinski ◽  
James A. Golen ◽  
Badiadka Narayana ◽  
Hemmige S. Yathirajan ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Solvent Molecule ◽  
Pyrazole Ring ◽  
Central Layer ◽  
Form Complex ◽  
Common Precursor ◽  
Solvent Molecules ◽  
Hydrogen Bonded

Two different heterocycles, a pyrazole and an oxadiazine, are formed by the reactions of a common precursor, (2RS,3SR)-2,3-dibromo-1,3-bis(4-fluorophenyl)propan-1-one, with different simple hydrazines. In 3,5-bis(4-fluorophenyl)-1-phenyl-1H-pyrazole, C21H14F2N2, (I), formed using phenylhydrazine, there is some aromatic-type delocalization in the pyrazole ring, and the molecules are linked into simple chains by a single C—H...π(arene) hydrogen bond. The reaction with 4-hydroxybenzohydrazide gives (5RS,6SR)-6-(4-fluorobenzoyl)-5-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5,6-dihydro-4H-1,3,4-oxadiazine, which was crystallized fromN,N-dimethylformamide to give the monosolvate, C22H16F2N2O3·C3H7NO, (II), in which the solvent molecule is disordered over two sets of atomic sites having occupancies of 0.557 (10) and 0.443 (10). The oxadiazine molecules in (II) are linked by a combination of N—H...N and C—H...O hydrogen bonds to form complex sheets, having the hydrogen bonds in the central layer and with the solvent molecules attached at the outer faces by O—H...O hydrogen bonds.

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