The title compound, C10H13NO4, is essentially planar, with an r.m.s. deviation of 0.049 Å. An intra-molecular C-H⋯O hydrogen bond occurs and the amino group forms an intra-molecular N-H⋯Oester hydrogen bond; the other H atom forms an inter-molecular N-H⋯Ocarbon-yl hydrogen bond, leading to the formation of a helical chain that runs along the b-axis direction.

In the title compound, C(11)H(12)N(2)O(3)·H(2)O, the water mol-ecule is a hydrogen-bond donor to the double-bond amide and the carbonyl O atoms of two acid mol-ecules; it is also a hydrogen-bond acceptor to the acid -OH and amide -NH- groups. These hydrogen-bonding inter-actions give rise to a layer structure, with the layers parallel to the ab plane.

Protein backbone helical structures have the same values of dihedral angles φ and ψ from unit to unit and thus, can be uniquely determined by a pair (φ,ψ). We focus our attention on two types of protein secondary structure αand 310-helices stabilized by 1-5 and 1-4 hydrogen bonding pattern respectively. Even though both αand 310-helices each represent a group of helices, various studies show th...

The PM3 semiempirical quantum-mechanical method was found to systematically describe intermolecular hydrogen bonding in small polar molecules. PM3 shows charge transfer from the donor to acceptor molecules on the order of 0.02-0.06 units of charge when strong hydrogen bonds are formed. The PM3 method is predictive; calculated hydrogen bond energies with an absolute magnitude greater than 2 kcal...

We have determined the hydrogen-bond geometry in liquid water from 0 to 80 degrees C by combining measurements of the proton magnetic shielding tensor with ab initio density functional calculations. The resulting moments of the distributions of hydrogen-bond length and angle are direct measures of thermal disorder in the hydrogen-bond network. These moments, and the distribution functions that ...

molecular dynamic simulation is a powerful method that monitors all variations in the atomic level in explicit solvent. by this method we can calculate many chemical and biochemical properties of large scale biological systems. in this work all-atom molecular dynamics simulation of polyalanine (pa) was investigated in the presence of 0.224, 0.448, 0.673, 0.897 and 1.122 m of guanidinium chlorid...

            We report herein the synthesis of ¾ substituted benzene sulfonamides linked via phenyl ring to a benzothiazole moiety. The title compounds in the two series namely N-(4-(benzothiazole-2-yl) phenyl) 4- substituted benzene sulfonamides and N-(4-(benzothiazole-2-yl) phenyl) 3- substituted benzene sulfonamides were synthesized by condensing 2-(3/4-aminophenyl) benzothiazole with various...

In the present work, the sensitivity to the moisture (hygroscopisity) is studied for 3,4-dinitropyrazole (DNP) as a famous energetic molecule. All of the DNP-H2O complex systems (1-3) as well as individual molecules were optimized and bond lengths, bond angles, dihedral angles, charge transfer and stability via NBO analysis, corrected interaction energies with ZPE + BSSE and hydrogen bonds anal...

There are 30026 symmetry-distinct ways to arrange 20 water molecules in a dodecahedral cage with nearly optimum hydrogen bond lengths and angles, analogous to the arrangements that give rise to the zero-point entropy in ice-Ih. The energy of hydrogen bond isomers in (H2O)20 , assumed to be similar in the past, differs by up to 70 kcal/mol. The isomers differ widely in their hydrogen bond length...

The Schiff base mol-ecule of the title compound, C(15)H(14)N(2)O(4)·H(2)O, adopts a trans configuration with respect to the C=N double bond; the Schiff base itself is almost planar (r.m.s. deviation for all non-H atoms = 0.040 Å). The amido N atom is the hydrogen-bond donor to the water mol-ecule, which is the hydrogen-bond donor to the hydr-oxy groups of two neighboring mol-ecules. One of the ...