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1

Intermolecular interactions in 2,4-dinitrophenylhydrazine hydrochloride hydrate: X-ray structural and quantum mechanical study

100%

Kruszynski R.

Open Chemistry

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2008

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vol. 6

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issue 4

542-548

EN

2,4-dinitrophenylhydrazine hydrochloride hydrate (I) was determined by X-ray crystallography, and the intermolecular interaction energies were calculated in terms of Natural Bond Orbital analysis. The asymmetric unit of (I) consists of a dinitrophenylhydrazinium cation, a chloride anion and a water molecule. The interatomic distances and angles in (I) show no unusual values. In the structure there are intermolecular N-H⊎⊎⊎O, N-H⊎⊎⊎Cl, O-H⊎⊎⊎Cl, C-H⊎⊎⊎O hydrogen bonds with bonding energy ranging form 16.03 to 0.76 kcal mol−1. These hydrogen bonds create the following N1 motifs: 6D, S(5), S(6), C(6), C(9). N1D motifs become infinite at the third level and are 2C 32(6), C 32(7). [...]

2

Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

100%

Todorov P., Petrova R., Naydenova E., Shivachev B.

Open Chemistry

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2009

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vol. 7

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issue 1

14-19

EN

The crystal structures of 3-amino-cycloheptanespiro-4′-imidazolidine-2′,5′-dione (I) {systematic name: 3-amino-1,3-diazaspiro[4.6] undecane-2,4-dione} and 3-amino-cyclooctanespiro-4′-imidazolidine-2′,5′-dione (II) {systematic name: 3-amino-1,3-diazaspiro[4.7] dodecane-2,4-dione}, have been determined. In both compounds the polar hydantoin groups cause molecules to aggregate via N-H...O and N-H...N interactions, forming a layer structure, in which the cycloalkane rings project outwards from the central, more polar, region. The observed molecular structure is compared with that calculated by density functional theory methods. [...]

3

Density and temperature effect on hydrogen-bonded clusters in water - MD simulation study

100%

Swiatla-Wojcik D., Pabis A., Szala J.

Open Chemistry

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2008

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vol. 6

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issue 4

555-561

EN

Molecular dynamics NVE simulations have been performed for five thermodynamic states of water including ambient, sub-and supercritical conditions. Clustering of molecules via hydrogen bonding interaction has been studied with respect to the increasing temperature and decreasing density to examine the relationship between the extent of hydrogen bonding and macroscopic properties. Calculations confirmed decrease of the average number of H-bonds per molecule and of cluster-size with increasing temperature and decreasing density. In the sub-and supercritical region studied, linear correlations between several physical quantities (density, viscosity, static dielectric constant) and the total engagement of molecules in clusters of size k > 4, Pk>4, have been found. In that region there was a linear relationship between Pk>4 and the average number of H-bonds per water molecule. The structural heterogeneity resulting from hydrogen bonding interactions in low-density supercritical water has been also discussed. [...]

4

Self-assembled hydrogen-bonded coordination networks in two copper(II) carboxylates with 4-pyridylmethanol

88%

Maroszová J., Moncol J., Padělková Z., Sillanpää R., Lis T., Koman M.

Open Chemistry

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2011

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vol. 9

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issue 3

453-459

EN

The crystal and molecular structure of [Cu(nif)2(4-PM)2]·CH3OH (1) and [Cu(2-Clbz)2(4-PM)2(H2O)] (2), (where nif = niflumate anion, 2-Clbz = 2-chlorobenzoate anion and 4-PM is the 4-pyridylmethanol), have been determinated by X-ray crystallography. The Cu2+ cation in (1), is coordinated by two pairs of oxygen atoms from asymmetric bidentate niflumate anions and by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands in trans position forming an extremely elongated bipyramid. The Cu2+ cation in (2), is coordinated by a pair of oxygen atoms from monodentate 2-chlorobenzoate anions, further by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands and finally by a water oxygen atom forming a tetragonal-pyramidal coordination polyhedron. The molecules of both complexes in crystal structures are linked by O-H…O hydrogen bonds, which created a three-dimensional hydrogen-bonding networks. The Π-Π stacking interactions are also observed in crystal structures of complex 2. The spectral properties (IR and electronic spectra) of both complexes were also investigated.

5

The synthesis, structure and physical properties of lanthanide(III) complexes with nicotinic acid

88%

Hojnik N., Kristl M., Golobič A., Jagličić Z., Drofenik M.

Open Chemistry

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2014

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vol. 12

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issue 2

220-226

EN

This article reports the synthesis of novel, rare-earth coordination complexes with nicotinic acid. Three compounds with the general formula Ln2[(C5H4NCOO)6(H2O)4] (Ln = Yb, 1; Ln = Gd, 2; Ln = Nd, 3) were prepared from relatively cheap and readily available reactants. Their compositions and structure were characterized by IR spectroscopy and single-crystal X-ray diffraction. The magnetic and thermogravimetric properties were also studied. The complexes consist of centrosymetric, dimeric molecules having all six nicotinato ligands coordinated with the central atom in the bidentate mode. The coordination environment of the Ln3+ for all three compounds is 8. Here we describe the crystal structure of Yb and Gd complexes with nicotinic acid.

6

Watson-crick base pairs with thiocarbonyl groups: How sulfur changes the hydrogen bonds in DNA

88%

Guerra C., Baerends E., Bickelhaupt F.

Open Chemistry

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2008

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vol. 6

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issue 1

15-21

EN

We have theoretically analyzed mimics of Watson-Crick AT and GC base pairs in which N-H···O hydrogen bonds are replaced by N-H···S, using the generalized gradient approximation (GGA) of density functional theory at BP86/TZ2P level. The general effect of the above substitutions is an elongation and a slight weakening of the hydrogen bonds that hold together the base pairs. However, the precise effects depend on how many, and in particular, on which hydrogen bonds AT and GC are substituted.. Another purpose of this work is to clarify the relative importance of electrostatic attraction versus orbital interaction in the hydrogen bonds involved in the mimics, using a quantitative bond energy decomposition scheme. At variance with widespread believe, the orbital interaction component in these hydrogen bonds is found to contribute more than 40% of the attractive interactions and is thus of the same order of magnitude as the electrostatic component, which provides the remaining attraction. [...]

7

Analysis of Structural Changes in Starch-Aluminosilicate Binder and Molding Sand with its Participation after Physical Curing

75%

Żymankowska-Kumon S., Grabowska B., Bobrowski A., Kaczmarska K., Cukrowicz S.

Archives of Foundry Engineering

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2018

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issue 3

Refine search results

Intermolecular interactions in 2,4-dinitrophenylhydrazine hydrochloride hydrate: X-ray structural and quantum mechanical study

Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

Density and temperature effect on hydrogen-bonded clusters in water - MD simulation study

Self-assembled hydrogen-bonded coordination networks in two copper(II) carboxylates with 4-pyridylmethanol

The synthesis, structure and physical properties of lanthanide(III) complexes with nicotinic acid

Watson-crick base pairs with thiocarbonyl groups: How sulfur changes the hydrogen bonds in DNA

Analysis of Structural Changes in Starch-Aluminosilicate Binder and Molding Sand with its Participation after Physical Curing