the influence of cation-π interactions on the strength and nature of intramolecular o...h hydrogen bond has been investigated by quantum chemical calculations in orthohydroxy benzaldehyde (hba) compound. ab initio calculations have been performed at mp2/6-311++g** level of theory. vibrational frequencies and physical properties such as chemical potential and chemical hardness of these compounds...

  A theoretical density functional theory (DFT) study was performed on a series of the neutral N-phenylthiourea substituents (p-OC2H5, p-CH3, m-CH3, H, p-Cl, p-Br, m-Cl, and p-NO2) as the sensor of acetate and fluoride anions. The hydrogen bond character was analyzed as a scale ...

The NMR spectra of azo dyes, 5-arylazobarbituric (5a-g), 5-arylazo-1,3-dimethylbarbituric(6a-g) and 5-arylazothiobarbituric acids (7a-g) were studied in DMSO-d6 in differentconcentrations. An intramolecular hydrogen bond was observed and indicating that thehydrazone forms is mostly predominant. The peak of the hydrazone proton was severelybroadened and its chemical shift appeared at down field ...

A fragment of Histidine rich protein II (HRP II 215-236) was investigated by 14N and 17O electric field gradient, EFG, tensor calculations using DFT. This study is intended to explore the differences between 310-helix and α-helix of HRPII both in the gas phase and in solution. To achieve the aims, the 17O and 14N NQR parameters of a fragment of HRPII (215-236) for both structures are calculated...

Hydrogen bonds profoundly influence the architecture and activity of biological macromolecules. Deep appreciation of hydrogen bond contributions to biomolecular function thus requires a detailed understanding of hydrogen bond structure and energetics and the relationship between these properties. Hydrogen bond formation energies (ΔGf) are enormously more favorable in aprotic solvents than in wa...

Quantification of backbone hydrogen bond energies in protein folding has remained elusive despite extensive theoretical and experimental investigations over the past 70 years. This is due to difficulties in experimental mutagenesis study as well as the lack of quantitatively reliable methods in theoretical calculation. Recent advance in experiment has enabled accurate measurement of site-specif...

The title compound, C(14)H(11)BrN(2)O(5)·2H(2)O, crystallizes as hydrogen-bonded sheets. The 2-hydr-oxy group on the benzyl-idene group forms an intra-molecular hydrogen bond to the N atom of the C=N double bond. The amino N atom is a hydrogen-bond donor to a water mol-ecule. The hydr-oxy group on the benzohydrazide group is a hydrogen-bond donor to one acceptor site, whereas each water mol-ecu...