Term: photoisomerization
https://doi.org/10.1351/goldbook.P04622

Definition:
Photochemical process leading to an isomerization of the substrate, either by bond rotation, skeletal rearrangement or atom- or group- transfer.

Notes:
0) Typical examples are cis-@C01092@ photosomerization of @A00224@, polyenes and phototautomerization.
1) Photochemical pathways have the advantage over thermal and catalytic methods of giving @I03289@ mixtures (photostationary states) rich in thermodynamically @U06569@ isomers.
2) Photoisomerization is the primary @P04585@ of the @C01076@ in several biological photoreceptors such as retinal @P04898@ (e.g., rhodopsin), phytochromes, and the photoactive yellow protein.

Related Terms:
1) trans (http://doi.org/10.1351/goldbook.C01092).
2) alkenes (http://doi.org/10.1351/goldbook.A00224).
3) isomer (http://doi.org/10.1351/goldbook.I03289).
4) unstable (http://doi.org/10.1351/goldbook.U06569).
5) photochemical reaction (http://doi.org/10.1351/goldbook.P04585).
6) chromophore (http://doi.org/10.1351/goldbook.C01076).
7) proteins (http://doi.org/10.1351/goldbook.P04898).
8) isomerization (http://doi.org/10.1351/goldbook.I03295).
9) rearrangement (http://doi.org/10.1351/goldbook.R05194).

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 393 (https://doi.org/10.1351/pac200779030293)

Citation: 'photoisomerization' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.P04622

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