The Schiff base mol-ecule of the title compound, C(15)H(14)N(2)O(4)·C(3)H(7)NO, adopts a trans configuration with respect to the C=N double bond; the Schiff base itself is nearly planar (r.m.s. deviation 0.20 Å). The amido N atom is a hydrogen-bond donor to the dimethyl-formamide solvate mol-ecule. One of the hydr-oxy groups forms an intra-molecular hydrogen bond to the N atom of the C=N double...

There has recently been an increasing interest in controlling macromolecular conformations and interactions through halogen bonding. Halogen bonds are favorable electrostatic interactions between polarized, electropositive chlorine, bromine, or iodine atoms and electronegative atoms such as oxygen or nitrogen. These interactions have been likened to hydrogen bonds in terms of their favored acce...

Hydrogen bonding interaction is one of the most important intermolecular interactions. This interaction has been known almost for a century, but it is popular only after the work of Pauling, who was the first to give a definition of the hydrogen bond. According to Pauling, ‘under certain conditions an atom of hydrogen is attracted by rather strong forces to two atoms, instead of only one, so th...

In the present work, the substituent effect on the strength of H-bonds in the guanine – cytosine base pair was studied when the substituents are connected to the guanine base through a phenyl ring. In this study, guanine was substituted in the H8 and H9 positions by electron donating (ED) and electron withdrawing (EW) groups mediated by a phenyl ring in the gas phase. The calculations were perf...

The effect of a homogeneous external electric field parallel to the hydrogen bond in the FH...FH dimer has been studied by theoretical methods. The quantum theory of atoms in molecules methodology has been used for analyzing the electron distribution of the dimer, calculated with different hydrogen bond distances and external field magnitudes. It is shown that an electric field in the opposite ...

Ultrafast polarization and wavelength selective IR pump-probe spectroscopy is used to measure the inertial and long time orientational dynamics of pi-hydrogen bonding complexes. Inertial orientational relaxation is sensitive to the angular potential associated with the hydrogen bond. The complexes studied are composed of phenol-OD (hydroxyl hydrogen replaced by deuterium) and various pi-base so...

The catalytic importance of enzyme active-site interactions is frequently assessed by mutating specific residues and measuring the resulting rate reductions. This approach has been used in bacterial ketosteroid isomerase to probe the energetic importance of active-site hydrogen bonds donated to the dienolate reaction intermediate. The conservative Tyr16Phe mutation impairs catalysis by 10(5)-fo...

Recently, we defined 'hydrogen-bond radii' for various hydrogen-bond donors, DH where D = F, Cl, Br, CN, HO or CCH from an empirical analysis. It was shown that the A...H distances in B...HD complexes could be written as a sum of hydrogen bond radius for DH and a constant acceptor radius for A, which is the bonding atom/centre in B. This manuscript reports the determination of the hydrogen-bond...

Isotopic effects on the formation and dissociation kinetics of hydrogen bonds are studied in real time with ultrafast chemical exchange spectroscopy. The dissociation time of hydrogen bond between phenol-OH and p-xylene (or mesitylene) is found to be identical to that between phenol-OD and p-xylene (or mesitylene) in the same solvents. The experimental results demonstrate that the isotope subst...

Hydrogen bond networks are key elements of biological structure and function. Nevertheless, their structural properties are challenging to assess within complex macromolecules. Hydrogen-bonded protons are not observed in the vast majority of protein X-ray structures, and static crystallographic models provide limited information regarding the dynamical coupling within hydrogen bond networks. We...