dimers

Dimers are chemical species formed when two monomer units join to create a single entity. The two units may be identical, yielding a homodimer, or different, yielding a heterodimer. Dimers arise when two molecules or two subunits associate in solution or as part of a larger molecule, and they are a common concept across chemistry, biochemistry, and materials science.

Dimerization can be covalent, such as disulfide-linked protein dimers, or noncovalent, governed by hydrogen bonds, ionic interactions, or van der Waals forces. Noncovalent dimers are often reversible and exist in dynamic equilibrium with monomeric forms. The equilibrium position depends on factors like concentration, temperature, solvent, and pH.

In biology, many proteins function as dimers, and dimerization can regulate activity, DNA binding, or receptor signaling. Enzymes, transcription factors, and membrane receptors frequently rely on dimer formation for proper function. In chemistry and materials science, dimers include simple diatomic molecules considered as two-atom assemblies, as well as more complex entities such as hydrogen-bonded water dimers or aromatic hydrocarbon dimers.

Dimers are studied using techniques such as spectroscopy, crystallography, and calorimetry to determine bonding, structure, and association constants. Understanding dimerization helps explain mechanisms in biology and materials science and can inform drug design, where modulating dimer formation can alter function or activity.