The title compound, C(10)H(12)N(2)O(4), adopts a trans configuration with respect to the C=N double bond. The non-H atoms of the mol-ecule are essentially coplanar, with a maximum deviation of 0.015 (2) Å. An intra-molecular O-H⋯N inter-action is observed. In the crystal structure, the mol-ecules are linked into a two-dimensional network parallel to the ac plane by N-H⋯O hydrogen bonds involvin...

In this study Klason lignins from Eucalyptus grandis (LEUG) and Pinus taeda (LPIT) were characterized using Fourier transform infrared (FTIR) spectroscopy and thermogravimetry (TGA). The degradation kinetic parameters were determined by TGA using the Kissinger method. Thermogravimetric results showed that LPIT had higher thermal stability and also higher activation energy than LEUG. FTIR result...

A novel class of stereocomplexes is described by the interaction of helically complementary poly(phenylacetylene)s (PPAs) carrying an α-methoxy-α-trifluoromethylphenylacetamide pendant group. The formation of the stereocomplex requires the presence of cis amide bonds on the external crest of the polymer to provide efficient cooperative supramolecular hydrogen bonding between matching enantiomer...

The one-dimensional model of Lippincott and Schroeder for hydrogen bond has Been re-examined and it has been shown that O-H bond distance depends on repulsive van der Waals and attractive electrostatic potentials.it has been shown that constant b in the van der Waals repulsion potential is not transferable to all hydrogen bonds. The possibility of obtaining the semi-empircal parameters i...

The characteristics of N--H...O, O--H...O, and C--H...O hydrogen bonds and other weak intermolecular interactions are analyzed in a large and diverse group of 251 protein-ligand complexes using a new computer program that was developed in-house for this purpose. The interactions examined in the present study are those which occur in the active sites, defined here as a sphere of 10 A radius arou...

The title compound, C(23)H(26)F(2)N(2)O(4), is a dipeptidic inhibitor of γ-secretase, one of the enzymes involved in Alzheimer's disease. The molecule adopts a compact conformation, without intramolecular hydrogen bonds. In the crystal structure, one of the amide N atoms forms the only intermolecular N-H...O hydrogen bond; the second amide N atom does not form hydrogen bonds. High-resolution sy...

A series of conformationally restricted triol and tetrol systems containing intramolecular hydrogen bond arrays has been prepared and characterized by X-ray crystallography and NMR spectroscopy. NMR isotopic perturbation measurements in DMSO-d6 and CD2Cl2 reveal that this methodology can be used to detect the spatial proximity of up to four contiguous hydroxyl groups sharing a 1,3-, 1,4-, or 1,...

The measurement of absorption spectra using angle-dependent terahertz (THz) time-domain spectroscopy for amino acid single crystals of l-cysteine and l-histidine is reported for the first time. Linearly polarized THz radiation enables us to observe angle-dependent far-infrared absorption spectra of amino acid single crystals and determine the direction of the oscillating dipole of the molecules...

The weak intermolecular interaction between 2,2,2-trifluoroethanol (TFE) and 3-chloro-2-methyl-1propene (CMP) has been investigated by gas phase FTIR spectroscopy and DFT calculations. CMP offers two hydrogen bond docking sites to the hydrogen bond donor: the chlorine atom (O–H/Cl) and the C]C p electron system (O–H/p). DFT calculations suggest that MeOH approaches CMP in five different orienta...

Water is an associated liquid in which the main intermolecular interaction is the hydrogen bond (HB) which is limited to four per atom, independently of the number of neighbours. We have considered a hydrogen bond net superposed on Bernal’s geometric model for liquids, which allows for different local environments for the liquid particles. In this study, a mean-field treatment of the two-dimens...