# Dimerization

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Chemical process of joining two molecular entities by bonds of any kind

"Dimer (chemistry)" redirects here. For other uses, see [Dimer (disambiguation)](/source/Dimer_(disambiguation)).

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In [chemistry](/source/Chemistry), **dimerization** is the process of joining two identical or similar [molecular entities](/source/Molecular_entity) by [bonds](/source/Chemical_bond). The resulting bonds can be either strong or weak. Many symmetrical [chemical species](/source/Chemical_species) are described as **dimers**, even when the [monomer](/source/Monomer) is unknown or highly unstable.[1]

The term *homodimer* is used when the two subunits are identical (e.g. A–A) and *heterodimer* when they are not (e.g. A–B). The reverse of dimerization is often called [dissociation](/source/Dissociation_(chemistry)). When two oppositely-charged [ions](/source/Ion) associate into dimers, they are referred to as *Bjerrum pairs*,[2] after Danish chemist [Niels Bjerrum](/source/Niels_Bjerrum).

## Noncovalent dimers

Dimers of [carboxylic acids](/source/Carboxylic_acid) are often found in the vapour phase.

[Anhydrous](/source/Anhydrous) [carboxylic acids](/source/Carboxylic_acid) form dimers by hydrogen bonding of the acidic hydrogen and the carbonyl oxygen. For example, [acetic acid](/source/Acetic_acid) forms a dimer in the gas phase, where the monomer units are held together by [hydrogen bonds](/source/Hydrogen_bond).[3] Many OH-containing molecules form dimers, e.g. the [water dimer](/source/Water_dimer).

Dimers that form based on weak [electrostatic interaction](/source/Electrostatic_Interaction) and/or [van der Waals interactions](/source/Van_der_Waals_interactions) have a short lifetime, but can be stabilized through special laboratory setups such as [matrix-isolation](/source/Matrix_isolation). A prominent example is the [carbon dioxide](/source/Carbon_dioxide) dimer,[4] which is likely to be relevant to Venus atmosphere.[5]

[Excimers](/source/Excimers) and [exciplexes](/source/Exciplex) are [excited](/source/Excited_state) structures with a short lifetime. For example, [noble gases](/source/Noble_gases) do not form stable dimers, but they do form the [excimers](/source/Excimers) Ar2*, Kr2* and Xe2* under high pressure and electrical stimulation.[6]

## Covalent dimers

The dimerization of [cyclopentadiene](/source/Cyclopentadiene) gives dicyclopentadiene, although this might not be readily apparent on initial inspection.  This dimerization is reversible.

[Molecular](/source/Molecular) dimers are often formed by the reaction of two identical compounds e.g.: 2A → A−A. In this example, [monomer](/source/Monomer) "A" is said to dimerize to give the dimer "A−A".

[Dicyclopentadiene](/source/Dicyclopentadiene) is an asymmetrical dimer of two [cyclopentadiene](/source/Cyclopentadiene) molecules that have reacted in a [Diels-Alder reaction](/source/Diels-Alder_reaction) to give the product. Upon heating, it "cracks" (undergoes a retro-Diels-Alder reaction) to give identical monomers:

- C 10 H 12 ⟶ 2 C 5 H 6 {\displaystyle {\ce {C10H12 -> 2 C5H6}}}

Many nonmetallic elements occur as dimers: [hydrogen](/source/Hydrogen), [nitrogen](/source/Nitrogen), [oxygen](/source/Oxygen), and the [halogens](/source/Halogen) [fluorine](/source/Fluorine), [chlorine](/source/Chlorine), [bromine](/source/Bromine) and [iodine](/source/Iodine). Some metals form a proportion of dimers in their vapour phase: [dilithium](/source/Dilithium) (Li2), [disodium](/source/Disodium) (Na2), [dipotassium](/source/Dipotassium) (K2), [dirubidium](/source/Dirubidium) (Rb2) and [dicaesium](/source/Dicaesium) (Cs2). Such elemental dimers are [homonuclear](/source/Homonuclear_molecule) [diatomic molecules](/source/Diatomic_molecule).

## Polymer chemistry

In the context of [polymers](/source/Polymer), "dimer" also refers to the [degree of polymerization](/source/Degree_of_polymerization) 2, regardless of the stoichiometry or [condensation reactions](/source/Condensation_reaction).

One case where this is applicable is with [disaccharides](/source/Disaccharide). For example, [cellobiose](/source/Cellobiose) is a dimer of [glucose](/source/Glucose), even though the formation reaction produces [water](/source/Water):

- 2 C 6 H 12 O 6 ⟶ C 12 H 22 O 11 + H 2 O {\displaystyle {\ce {2 C6H12O6 -> C12H22O11 + H2O}}}

Here, the resulting dimer has a stoichiometry different from the initial pair of monomers.

Disaccharides need not be composed of the same [monosaccharides](/source/Monosaccharide) to be considered dimers. An example is [sucrose](/source/Sucrose), a dimer of [fructose](/source/Fructose) and glucose, which follows the same reaction equation as presented above.

Amino acids can also form dimers, which are called [dipeptides](/source/Dipeptide). An example is [glycylglycine](/source/Glycylglycine), consisting of two [glycine](/source/Glycine) molecules joined by a [peptide bond](/source/Peptide_bond). Other examples include [aspartame](/source/Aspartame) and [carnosine](/source/Carnosine).

## Inorganic and organometallic dimers

Many molecules and ions are described as dimers, even when the monomer is elusive.

### Boranes

Borane and diborane

[Diborane](/source/Diborane) (B2H6) is an dimer of [borane](/source/Borane), which is elusive and rarely observed. Almost all compounds of the type R2BH exist as dimers.[7]

### Organoaluminium compounds

Trimethylaluminium dimer

[Trialkylaluminium compounds](/source/Organoaluminium_chemistry) can exist as either monomers or dimers, depending on the [steric bulk](/source/Steric_effects) of the groups attached. For example, [trimethylaluminium](/source/Trimethylaluminium) exists as a dimer, but trimesitylaluminium adopts a monomeric structure.[8]

### Organochromium compounds

Cyclopentadienylchromium tricarbonyl dimer exists in measureable equilibrium quantities with the monometallic radical (C5H5)Cr(CO)3.[9]

## Biochemical dimers

### Pyrimidine dimers

[Pyrimidine dimers](/source/Pyrimidine_dimers) (also known as thymine dimers) are formed by a [photochemical reaction](/source/Photochemical_reaction) from pyrimidine [DNA bases](/source/DNA_base) when exposed to ultraviolet light.[8] This cross-linking causes [DNA mutations](/source/Mutation), which can be [carcinogenic](/source/Carcinogenic), causing [skin cancers](/source/Skin_cancer).[8] When [pyrimidine dimers](/source/Pyrimidine_dimer) are present, they can block [polymerases](/source/Polymerase), decreasing DNA functionality until it is repaired.[8]

### Protein dimers

Tubulin dimer

[Protein dimers](/source/Protein_dimer) arise from the interaction between two [proteins](/source/Protein) which can interact further to form larger and more complex [oligomers](/source/Oligomer).[10] For example, [tubulin](/source/Tubulin) is formed by the dimerization of [α-tubulin](/source/Tubulin) and [β-tubulin](/source/Tubulin) and this dimer can then [polymerize](/source/Polymerization) further to make [microtubules](/source/Microtubule).[11] For symmetric proteins, the larger protein complex can be broken down into smaller identical [protein subunits](/source/Protein_subunit), which then dimerize to decrease the genetic code required to make the functional protein.[10]

### G protein-coupled receptors

As the largest and most diverse family of [receptors](/source/Receptor_(biochemistry)) within the human genome, [G protein-coupled receptors](/source/G_protein-coupled_receptor) (GPCR) have been studied extensively, with recent studies supporting their ability to form dimers.[12] GPCR dimers include both homodimers and heterodimers formed from related members of the GPCR family.[13] While not all, some GPCRs require dimerization to function, such as [GABAB](/source/GABAB_receptor)-receptor, emphasizing the importance of dimers in biological systems.[14]

Receptor tyrosine kinase dimerization

### Receptor tyrosine kinase

Much like for G protein-coupled receptors, dimerization is essential for [receptor tyrosine kinases](/source/Receptor_tyrosine_kinase) (RTK) to perform their function in [signal transduction](/source/Signal_transduction), affecting many different cellular processes.[15] RTKs typically exist as monomers, but undergo a [conformational change](/source/Conformational_change) upon [ligand](/source/Ligand_(biochemistry)) binding, allowing them to dimerize with nearby RTKs.[16][17] The dimerization activates the [cytoplasmic](/source/Cytoplasm) [kinase](/source/Kinase) [domains](/source/Protein_domain) that are responsible for further [signal transduction](/source/Signal_transduction).[15]

## See also

Wikimedia Commons has media related to [Dimers](https://commons.wikimedia.org/wiki/Dimers).

- [Monomer](/source/Monomer)

- [Oligomer](/source/Oligomer)

- [Polymer](/source/Polymer)

- [Protein dimer](/source/Protein_dimer)

- [Trimer](/source/Trimer_(chemistry))

## References

- ["IUPAC "Gold Book" definition"](http://goldbook.iupac.org/D01744.html). [doi](/source/Doi_(identifier)):[10.1351/goldbook.D01744](https://doi.org/10.1351%2Fgoldbook.D01744). [S2CID](/source/S2CID_(identifier)) [242984652](https://api.semanticscholar.org/CorpusID:242984652). Retrieved 2024-07-11.

1. **[^](#cite_ref-1)** ["Dimerization"](https://goldbook.iupac.org/terms/view/D01744).

1. **[^](#cite_ref-2)** Adar, Ram M.; Markovich, Tomer; Andelman, David (2017-05-17). "Bjerrum pairs in ionic solutions: A Poisson-Boltzmann approach". *The Journal of Chemical Physics*. **146** (19): 194904. [arXiv](/source/ArXiv_(identifier)):[1702.04853](https://arxiv.org/abs/1702.04853). [Bibcode](/source/Bibcode_(identifier)):[2017JChPh.146s4904A](https://ui.adsabs.harvard.edu/abs/2017JChPh.146s4904A). [doi](/source/Doi_(identifier)):[10.1063/1.4982885](https://doi.org/10.1063%2F1.4982885). [ISSN](/source/ISSN_(identifier)) [0021-9606](https://search.worldcat.org/issn/0021-9606). [PMID](/source/PMID_(identifier)) [28527430](https://pubmed.ncbi.nlm.nih.gov/28527430). [S2CID](/source/S2CID_(identifier)) [12227786](https://api.semanticscholar.org/CorpusID:12227786).

1. **[^](#cite_ref-3)** Karle, J.; Brockway, L. O. (1944). ["An Electron Diffraction Investigation of the Monomers and Dimers of Formic, Acetic and Trifluoroacetic Acids and the Dimer of Deuterium Acetate 1"](https://pubs.acs.org/doi/abs/10.1021/ja01232a022). *Journal of the American Chemical Society*. **66** (4): 574–584. [doi](/source/Doi_(identifier)):[10.1021/ja01232a022](https://doi.org/10.1021%2Fja01232a022). [ISSN](/source/ISSN_(identifier)) [0002-7863](https://search.worldcat.org/issn/0002-7863).

1. **[^](#cite_ref-4)** Fredin, Leif; Nelander, Bengt; Ribbegård, Göran (1974-12-01). ["On the dimerization of carbon dioxide in nitrogen and argon matrices"](https://linkinghub.elsevier.com/retrieve/pii/0022285274900770). *Journal of Molecular Spectroscopy*. **53** (3): 410–416. [doi](/source/Doi_(identifier)):[10.1016/0022-2852(74)90077-0](https://doi.org/10.1016%2F0022-2852%2874%2990077-0). [ISSN](/source/ISSN_(identifier)) [0022-2852](https://search.worldcat.org/issn/0022-2852).

1. **[^](#cite_ref-5)** Dinu, Dennis F.; Bartl, Pit; Quoika, Patrick K.; Podewitz, Maren; Liedl, Klaus R.; Grothe, Hinrich; Loerting, Thomas (2022-05-19). ["Increase of Radiative Forcing through Midinfrared Absorption by Stable CO2 Dimers?"](https://pubs.acs.org/doi/10.1021/acs.jpca.2c00857). *The Journal of Physical Chemistry A*. **126** (19): 2966–2975. [doi](/source/Doi_(identifier)):[10.1021/acs.jpca.2c00857](https://doi.org/10.1021%2Facs.jpca.2c00857). [ISSN](/source/ISSN_(identifier)) [1089-5639](https://search.worldcat.org/issn/1089-5639). [PMC](/source/PMC_(identifier)) [9125687](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9125687). [PMID](/source/PMID_(identifier)) [35533210](https://pubmed.ncbi.nlm.nih.gov/35533210).

1. **[^](#cite_ref-6)** Birks, J B (1975-08-01). ["Excimers"](https://iopscience.iop.org/article/10.1088/0034-4885/38/8/001). *Reports on Progress in Physics*. **38** (8): 903–974. [doi](/source/Doi_(identifier)):[10.1088/0034-4885/38/8/001](https://doi.org/10.1088%2F0034-4885%2F38%2F8%2F001). [ISSN](/source/ISSN_(identifier)) [0034-4885](https://search.worldcat.org/issn/0034-4885). [S2CID](/source/S2CID_(identifier)) [240065177](https://api.semanticscholar.org/CorpusID:240065177).

1. **[^](#cite_ref-7)** Shriver, Duward (2014). *Inorganic Chemistry* (6th ed.). W.H. Freeman and Company. pp. 306–307. [ISBN](/source/ISBN_(identifier)) [978-1-4292-9906-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4292-9906-0).

1. ^ [***a***](#cite_ref-:0_8-0) [***b***](#cite_ref-:0_8-1) [***c***](#cite_ref-:0_8-2) [***d***](#cite_ref-:0_8-3) Shriver, Duward (2014). *Inorganic Chemistry* (6th ed.). W.H. Freeman and Company. pp. 377–378. [ISBN](/source/ISBN_(identifier)) [978-1-4292-9906-0](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4292-9906-0).

1. **[^](#cite_ref-9)** Adams, Richard D.; Collins, Douglas E.; Cotton, F. Albert (1974). "Unusual structural and magnetic resonance properties of dicyclopentadienylhexacarbonyldichromium". *Journal of the American Chemical Society*. **96** (5): 749–754. [doi](/source/Doi_(identifier)):[10.1021/ja00810a019](https://doi.org/10.1021%2Fja00810a019).

1. ^ [***a***](#cite_ref-:1_10-0) [***b***](#cite_ref-:1_10-1) Marianayagam, Neelan J.; Sunde, Margaret; Matthews, Jacqueline M. (2004). "The power of two: protein dimerization in biology". *Trends in Biochemical Sciences*. **29** (11): 618–625. [doi](/source/Doi_(identifier)):[10.1016/j.tibs.2004.09.006](https://doi.org/10.1016%2Fj.tibs.2004.09.006). [ISSN](/source/ISSN_(identifier)) [0968-0004](https://search.worldcat.org/issn/0968-0004). [PMID](/source/PMID_(identifier)) [15501681](https://pubmed.ncbi.nlm.nih.gov/15501681).

1. **[^](#cite_ref-11)** Cooper, Geoffrey M. (2000). ["Microtubules"](https://www.ncbi.nlm.nih.gov/books/NBK9932/). *The Cell: A Molecular Approach. 2nd Edition*.

1. **[^](#cite_ref-12)** Faron-Górecka, Agata; Szlachta, Marta; Kolasa, Magdalena; Solich, Joanna; Górecki, Andrzej; Kuśmider, Maciej; Żurawek, Dariusz; Dziedzicka-Wasylewska, Marta (2019-01-01), Shukla, Arun K. (ed.), ["Chapter 10 - Understanding GPCR dimerization"](https://www.sciencedirect.com/science/article/pii/S0091679X18301080), *Methods in Cell Biology*, G Protein-Coupled Receptors, Part B, **149**, Academic Press: 155–178, [doi](/source/Doi_(identifier)):[10.1016/bs.mcb.2018.08.005](https://doi.org/10.1016%2Fbs.mcb.2018.08.005), [ISBN](/source/ISBN_(identifier)) [978-0-12-815107-5](https://en.wikipedia.org/wiki/Special:BookSources/978-0-12-815107-5), [PMID](/source/PMID_(identifier)) [30616817](https://pubmed.ncbi.nlm.nih.gov/30616817), [S2CID](/source/S2CID_(identifier)) [58577416](https://api.semanticscholar.org/CorpusID:58577416), retrieved 2022-10-27{{[citation](https://en.wikipedia.org/wiki/Template:Citation)}}: CS1 maint: work parameter with ISBN ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_work_parameter_with_ISBN))

1. **[^](#cite_ref-13)** Rios, C. D.; Jordan, B. A.; Gomes, I.; Devi, L. A. (2001-11-01). ["G-protein-coupled receptor dimerization: modulation of receptor function"](https://www.sciencedirect.com/science/article/pii/S0163725801001607). *Pharmacology & Therapeutics*. **92** (2): 71–87. [doi](/source/Doi_(identifier)):[10.1016/S0163-7258(01)00160-7](https://doi.org/10.1016%2FS0163-7258%2801%2900160-7). [ISSN](/source/ISSN_(identifier)) [0163-7258](https://search.worldcat.org/issn/0163-7258). [PMID](/source/PMID_(identifier)) [11916530](https://pubmed.ncbi.nlm.nih.gov/11916530).

1. **[^](#cite_ref-14)** Lohse, Martin J (2010-02-01). ["Dimerization in GPCR mobility and signaling"](https://www.sciencedirect.com/science/article/pii/S1471489209001672). *Current Opinion in Pharmacology*. GPCR. **10** (1): 53–58. [doi](/source/Doi_(identifier)):[10.1016/j.coph.2009.10.007](https://doi.org/10.1016%2Fj.coph.2009.10.007). [ISSN](/source/ISSN_(identifier)) [1471-4892](https://search.worldcat.org/issn/1471-4892). [PMID](/source/PMID_(identifier)) [19910252](https://pubmed.ncbi.nlm.nih.gov/19910252).

1. ^ [***a***](#cite_ref-:2_15-0) [***b***](#cite_ref-:2_15-1) Hubbard, Stevan R (1999-04-01). ["Structural analysis of receptor tyrosine kinases"](https://doi.org/10.1016%2FS0079-6107%2898%2900047-9). *Progress in Biophysics and Molecular Biology*. **71** (3): 343–358. [doi](/source/Doi_(identifier)):[10.1016/S0079-6107(98)00047-9](https://doi.org/10.1016%2FS0079-6107%2898%2900047-9). [ISSN](/source/ISSN_(identifier)) [0079-6107](https://search.worldcat.org/issn/0079-6107). [PMID](/source/PMID_(identifier)) [10354703](https://pubmed.ncbi.nlm.nih.gov/10354703).

1. **[^](#cite_ref-16)** Lemmon, Mark A.; Schlessinger, Joseph (2010-06-25). ["Cell Signaling by Receptor Tyrosine Kinases"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2914105). *Cell*. **141** (7): 1117–1134. [doi](/source/Doi_(identifier)):[10.1016/j.cell.2010.06.011](https://doi.org/10.1016%2Fj.cell.2010.06.011). [ISSN](/source/ISSN_(identifier)) [0092-8674](https://search.worldcat.org/issn/0092-8674). [PMC](/source/PMC_(identifier)) [2914105](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2914105). [PMID](/source/PMID_(identifier)) [20602996](https://pubmed.ncbi.nlm.nih.gov/20602996).

1. **[^](#cite_ref-17)** Lemmon, Mark A.; Schlessinger, Joseph; Ferguson, Kathryn M. (2014-04-01). ["The EGFR Family: Not So Prototypical Receptor Tyrosine Kinases"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970421). *Cold Spring Harbor Perspectives in Biology*. **6** (4) a020768. [doi](/source/Doi_(identifier)):[10.1101/cshperspect.a020768](https://doi.org/10.1101%2Fcshperspect.a020768). [ISSN](/source/ISSN_(identifier)) [1943-0264](https://search.worldcat.org/issn/1943-0264). [PMC](/source/PMC_(identifier)) [3970421](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3970421). [PMID](/source/PMID_(identifier)) [24691965](https://pubmed.ncbi.nlm.nih.gov/24691965).

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Adapted from the Wikipedia article [Dimerization](https://en.wikipedia.org/wiki/Dimerization) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Dimerization?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.