Are there molecules that interconvert between isomers upon irradiation with UV light?

Question

Skylar Alexander · Accepted Answer

Sometimes. There is one case I know of:

If you hit it with a camera flash (#hv#), you can catalyze the cis-trans isomerization of this azo dye compound, methyl red, into its cis configuration. Then what you could do is monitor it as it goes back to the more stable trans configuration and analyze its kinetics mechanism (it's a first order "half-life" decay).

There may be others, but that's one I could think of.

Easton Jones · Answer

undefined Yes, there are molecules known as photoisomerizable molecules that can interconvert between isomers upon irradiation with UV light. These molecules typically contain conjugated double bonds or other functional groups that undergo structural changes when exposed to UV radiation. The absorption of UV light promotes electronic transitions within the molecule, leading to isomerization reactions that result in changes in molecular configuration or conformation. Examples of photoisomerizable molecules include azobenzenes, stilbenes, and certain retinal derivatives found in visual pigments.