Hydrogen bond
A partial-covalent molecular interaction between a protic hydrogen and an electronegative acceptor.
A hydrogen bond is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen atom, covalently bonded to a more electronegative donor atom, interacts with another electronegative atom bearing a lone pair of electrons, the hydrogen bond acceptor. Hydrogen bonding plays a fundamental role in chemistry, biology, and materials science, being responsible for the anomalously high boiling point of water, the stabilization of protein and nucleic acid structures, and key properties of materials like paper, wool, and hydrogels.
- type
- Molecular interaction
- typical_donor_atoms
- Nitrogen (N), oxygen (O), fluorine (F)
- typical_acceptor_atoms
- Nitrogen (N), oxygen (O)
Lore & Background
The term 'hydrogen bond' is generally used for well-defined, localized interactions with significant charge transfer and orbital overlap, such as those in DNA base pairing or ice. In contrast, 'hydrogen-bonding interactions' is a broader term used when the interaction is weaker, more dynamic, or delocalized, such as in liquid water, supramolecular assemblies, or weak C-H···O interactions. This distinction is particularly relevant in structural biology, materials science, and computational chemistry, where hydrogen bonding spans a continuum from weak van der Waals-like interactions to nearly covalent bonding.
Reader's Guide
Hydrogen bonding arises from a combination of electrostatics, covalency (charge transfer by orbital overlap), and dispersion forces. This places hydrogen bonds stronger than van der Waals interactions but generally weaker than covalent or ionic bonds. The definition of hydrogen bonding has gradually broadened over time to include weaker attractive interactions, such as those involving sulfur, chlorine, or even carbon as donors. Hydrogen bonding plays a fundamental role in chemistry, biology, and materials science, mediating molecular recognition, enzyme catalysis, DNA replication, self-assembly, adhesion, and supramolecular organization.
Did You Know?
- Hydrogen bonds can be intramolecular, occurring within different parts of the same molecule.
- The resonance assisted hydrogen bond (RAHB) is characterized by π-delocalization involving the hydrogen atom.
- In the IR spectrum, hydrogen bonding shifts the X−H stretching frequency to lower energy, reflecting a weakening of the X−H bond.
Frequently Asked Questions
Who is Hydrogen bond?
Hydrogen bond is a partial-covalent molecular interaction in which a protic hydrogen, already covalently tied to an electronegative donor, reaches toward a lone pair on a second electronegative acceptor atom. It occupies a middle ground between a full covalent link and a simple electrostatic attraction.
What are Hydrogen bond's powers/role?
It is responsible for water's anomalously high boiling point, for locking proteins and nucleic acids into their functional three-dimensional folds, and for tuning key mechanical and thermal properties of many materials. Remove it and the structural architecture of life as we know it falls apart.
How does Hydrogen bond's story end?
Rather than a fixed endpoint, it exists in a perpetual cycle of formation and rupture at ambient temperatures. On the broader bonding spectrum it simply occupies the intermediate zone between ionic/electrostatic forces and full covalent bonds.
Why is Hydrogen bond important?
It is the non-covalent interaction that stabilizes the DNA double helix, the folded shapes of enzymes, and the liquid state of water near room temperature. Across chemistry, biology, and materials science it is arguably the single most consequential weak interaction.
Who are Hydrogen bond's key allies (donor and acceptor atoms)?
On the donor side, nitrogen, oxygen, and fluorine are the classic electronegative partners that hold the protic hydrogen in place. On the acceptor side, nitrogen and oxygen typically supply the lone pair of electrons that the hydrogen reaches for.
More in Chemical Bonding And Structure 1-21
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