Defining the hydrogen bond: An account (IUPAC Technical Report)

Abstract

Abstract:The term "hydrogen bond" has been used in the literature for nearly a century now. While its importance has been realized by physicists, chemists, biologists, and material scientists, there has been a continual debate about what this term means. This debate has intensified following some important experimental results, especially in the last decade, which questioned the basis of the traditional view on hydrogen bonding. Most important among them are the direct experimental evidence for a partial covalent nature and the observation of a blue-shift in stretching frequency following X-HؒؒؒY hydrogen bond formation (XH being the hydrogen bond donor and Y being the hydrogen bond acceptor). Considering the recent experimental and theoretical advances, we have proposed a new definition of the hydrogen bond, which emphasizes the need for evidence. A list of criteria has been provided, and these can be used as evidence for the hydrogen bond formation. This list is followed by some characteristics that are observed in typical hydrogen-bonding environments.

FTIR/PCA study of propanol in argon matrix: The initial stage of clustering and conformational transitions

“…[1,2] Convergence towards the bulk with increasing cluster size essentially depends on the nature of the observable physical properties, binding energies and on the resolution with which one looks at those. It is wellknown that the hydrogen bond (H-bond) occupies in the scale of binding energies an intermediate place between covalent and van der Waals interactions [3]. Therefore the simplest alcohols, molecules of which associate into various H-bond aggregates and even networks, can be considered as convenient models to investigate the cooperativity effects and the changes in the structural organization and conformations of molecular clusters sized over the nanoand mezzo-scales.…”

Communication: Competition between π⋯π interaction and halogen bond in solution: A combined 13C NMR and density functional theory study

“…The hydrogen bond is probably the most important noncovalent bond. 1,2 Other important noncovalent driving forces for supramolecular assembly include π · · ·π stacking interaction, [3][4][5][6][7][8][9][10][11][12][13] halogen bond, [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] etc. Noncovalent bonds are much weaker than the covalent bonds.…”

Conjugation in hydrogen-bonded systems

“…The reason becomes clear if we consider Fig. 10 where orbitals of (H 2 O) 5 cluster, which involves a tetracoordinated molecule, and those of (H 2 O) 8 and (H 2 O) 12 cages composed of fused molecular rings, are shown. One of the orbitals of (H 2 O) 5 (ϕ a in Fig.…”

“…Since that time, the scope of information about hydrogen bonds in the most diverse molecular systems and ensembles has kept increasing. As was mentioned in [5], if considering only the three-year period of 2006-2008, there appeared more than 31000 papers in English, devoted to hydrogen bonding indexed in SciFinder. The amount of papers published in all languages for the last three quarters of a century would be impossible to estimate.…”