Hydrogen Bonding


Also found in: Dictionary, Thesaurus, Medical, Acronyms.

Hydrogen Bonding

 

a form of chemical interaction of atoms in molecules characterized by the essential involvement of a hydrogen atom (H) already linked by a covalent bond to another atom (A). The A—H group acts as a proton donor (electron acceptor), while another group (or atom) B acts as an electron donor (proton acceptor). In other words, the A—H group behaves like an acid and group B like a base. Unlike the ordinary valence bond, which is denoted by a dash, the hydrogen bond is shown by dots, that is, A—H ··· B (in the limiting case of a symmetrical hydrogen bond, for example, in the acid potassium bifluoride K+(F ··· H ··· F), the difference between the two bonds disappears).

Groups able to form a hydrogen bond are A—H, where A is one of the atoms O, N, F, Cl, Br, and to a lesser extent C and S. The electron donor center B can be the same atoms O, N, S in various functional groups, such anions as F and Cl, and to a lesser degree aromatic rings and multiple bonds. If A—H and B belong to separate (different or identical) molecules, the hydrogen bond is called intermolecular, and if they are located in different parts of the same molecule, it is called intramolecular.

Hydrogen bonding differs from the van der Waals forces of mutual attraction common to all molecules in being directional and having a capacity for saturation, that is, by having the characteristics of ordinary (valence) chemical bonds. Unlike what was previously thought, hydrogen bonding does not reduce to electrostatic attraction between polar groups A—H and B but is considered as a donor-acceptor chemical bond. In respect to its binding energy, usually 3-8 kilocalories per mole, the hydrogen bond is intermediate between van der Waals interactions (equal to fractions of a kilocalorie per mole) and typical chemical bonds (tens of kilocalories per mole; 1 kilocalorie ≈ 4.19 × 103 joules).

The most widespread intermolecular bonding is hydrogen bonding. It leads to an association of identical or different molecules into various aggregate-complexes via hydrogen bonds, or to H-complexes, which under ordinary conditions undergo rapid equilibration. By this process we obtain both binary complexes (acid-base and cyclic dimers) and large structures (chains, rings, spirals, and plane and three-dimensional networks of linked molecules). The presence of such hydrogen bonds determines the properties of various solutions and liquids (primarily water and aqueous solutions, a series of industrial polymers—capron, nylon, and so forth) as well as the crystalline structures of many molecular crystals and crystal hydrates of inorganic compounds, among them, of course, ice. In exactly the same way hydrogen bonding substantially determines the structures of proteins, nucleic acids, and other biologically important compounds, and hence plays a major part in the chemistry of all vital processes. Because of the universal occurrence of hydrogen bonds, their role is also substantial in many other areas of chemistry and technology (distillation, extraction, adsorption, acid-base equilibrium processes, chromatography, catalysis, and so forth).

Since the formation of hydrogen bonds specifically alters the properties of the A—H and B groups, it is also reflected in the molecular properties, and this is shown, in part, in the vibrational spectra and proton magnetic resonance spectra. Hence spectroscopy, especially infrared spectroscopy, is an important method for studying hydrogen bonds and the processes depending on them.

REFERENCES

Pimentel, G., and A. McClellan. Vodorodnaia sviaz’. Moscow, 1964. (Translated from English.)
Vodorodnaia sviaz’: sb. st. Moscow, 1964.
Pauling, L. The Chemical Bond. New York, 1967.

A. V. IOGANSEN

References in periodicals archive ?
(10.) Luo, N, Wang, DN, Ying, SK, "Hydrogen Bonding Between Urethane and Urea: Band Assignment for the Carbonyl Region of FTIR Spectrum." Polymer, 37 3045-3047 (1996)
An analysis of the hydrogen bonding system within water helps to explain how the oceans of the Earth could produce a thermal spectrum with an apparent temperature much lower than their physical temperature [15, 16].
In LCh, there was a higher number of hydrogen bonds formed between hydroxyl and amino groups in the polymer chains, thus less amount of amino groups were available to form hydrogen bonding with water molecules from the moisture.
We saw the ordering is directly related to the hydrogen bonding in the structure, and how any changes can affect the energy gap of the material, said Wang.
Mulder, "A DFT study on intramolecular hydrogen bonding in 2-substituted phenols: conformations, enthalpies, and correlation with solute parameters," Journal of Physical Chemistry A, vol.
The reaction led to the formation of amide triazolecarboxylic acid group at which each group was capable of interacting with other groups via a six-point hydrogen bonding as shown in Fig.
In particular, the hydrogen bonding plays a very important role in the coadsorption of solvent molecules, including the formation of separated rows of strip structures.
Brian Dickens (1966-present) Groups land II (particularly calcium) phosphates and carbonates, their hydrates, and related compounds, hydrogen bonding, water in crystal structures, epitaxy, low temperatures, impurities/mixed populations in crystalline sites, computer programming.
Migration of the silane is then directed strongly to the silica surface where it accumulates by association through hydrogen bonding. One would expect that the directed orientation of the silane molecule, even by association, would make it act as a wetting agent, pacifying the polar sites on the surface of the silica.
The CSO2C asymmetric stretch peak faintly shifted to 1323.53cm-1 attributable to hydrogen bonding. The C-O asymmetric stretch peak in polysulfone (1244cm-1) moved to 1018.45cm-1 because of hydrogen shift bonding [40].
In terms of heterocyclic compounds, the properties of hydrogen bonding have been useful to ascribe insights about the stabilization of small rings, of which, the oxirane ([C.sub.2][H.sub.4]O) and aziridine (C2H5N) are some of them [12-15].
In fact, using neutrons, the team directly and unequivocally visualized hydrogen atoms and hydrogen bonding in xylanase at different stages of the catalytic reaction.