Authors: Yangyang Zhang | Han‐Shi Hu | Jian‐Biao Liu | Ling Jiang | Jun‐Bo Lu | Juan Li
Source: Chinese Science Bulletin (Chinese Version) (article, 2025-02-27)
Field: Chemistry — Physical and Theoretical Chemistry

A historical account and progress of hydrogen bonding in the past century <sec><p indent="0mm">Hydrogen bonding, as a relatively weak inter- or intra-molecular interaction, plays a crucial role not only in chemical compounds, biological structure, function, and conformational dynamics but also in chemical reactions such as proton transfer and catalysis. Therefore, hydrogen bonding has always been one of the important scientific issues in the fields of chemistry, material, and biology. The study of hydrogen bonds has a history of over <sc>125 years</sc> since the first recognition of somewhat unique properties of certain hydrogen-containing substances. However, due to the complexity of hydrogen bonding itself, its concept has been continuously expanded and improved with the development of experimental techniques and chemical theories since its discovery. There is still some mild debate on the definition and essence of hydrogen bonding in current research, which needs to be further explored with the development of theory. </sec><sec> Usually, hydrogen bonds are roughly divided into weak hydrogen bonds (5–10 kcal/mol) and strong hydrogen bonds (30–60 kcal/mol) based on their strength. At present, there are a large number of reviews and publications on hydrogen bonding in literature. Due to limitations of spaces, we will not try to be comprehensive, but rather only discuss some selected important literature. In this paper, we will briefly review the development history of the hydrogen bond concept over the past century. In 2011, the IUPAC updated the definition of hydrogen bond as: “The hydrogen bond is an attractive interaction between a hydrogen atom from a molecule or a molecular fragment A–H in which A is more electronegative than H, and an X atom or a group of atoms in the same or a different molecule, in which there is evidence of bond formation.” </sec><sec> Although there are still different understandings of the nature of hydrogen bonds, most studies converge to the viewpoint that hydrogen bonds are usually driven by electrostatic interactions, and in some cases (such as short hydrogen bonds and hydrogen bonds involving ions), charge transfer covalent interactions may account for a larger proportion, indicating that hydrogen bonds have a certain degree of covalent characteristics. Hydrogen bonds have both ionic and partially covalent properties, especially in strong hydrogen bonding systems where the bond energy far exceeds that of typical weak hydrogen bonds, resulting in significant covalent bonding properties. It has more or less reached a consensus that the dominant interactions that contribute to hydrogen bonding include: (a) electrostatic interactions; (b) charge transfer interactions; (c) Pauli repulsion; and (d) London dispersion. Yet controversy sometimes remains over the nature and mechanism of hydrogen bonding, which deserves further in-depth exploration. </sec><sec> Among the various models, using natural bond orbital (NBO) theory, Weinhold proposed a localized 3-center 2-electron (3c–2e) model for hydrogen bonding A–H<bold>···</bold>X, which advances the delocalized 3-center/4-electron (3c–4e) model proposed by Pimentel. This 3c-2e model suggests that hydrogen bonding essentially originates from, in addition to electrostatic interaction, the donor-acceptor interaction between the non-bonded lone pair orbitals (<italic>n</italic><sub>X</sub>) on the X atom and the empty antibonding orbitals of A–H (σ*<sub>A–H</sub> ← <italic>n</italic><sub>X</sub>). This covalent interaction and electrostatic interaction are the main sources of hydrogen bonding energy. This (3c–2e) model has been augmented with multiple (3c–2e) interactions between the donor and acceptor fragments in our work. </sec><sec> In summary, this article reviews the historical evolution, current research status, and recent progress of hydrogen bonding research, and provides a brief introduction to the definition, classification, and characteristics of hydrogen bonding. By selectively reviewing and analyzing the relevant literature related to hydrogen bonding, the aim is to provide insights and understanding on the complex, multifaceted nature of such interactions, and promote further investigations on hydrogen bonding theory and application research. </sec> Computer science Crystallography and molecular interactions ; Supramolecular Chemistry and Complexes ; Chemical Reaction Mechanisms