Isomerization is the process by which one molecule is transformed into another molecule which has exactly the same elements and exactly the same number of atoms of each element. The difference between the two molecules is how the elements are arranged e.g. ABC changes to BCA. Each molecular form is called an isomer.
Thermochromic and photochromic materials, such as leuco dyes exhibit isomerization in which one molecular form is colorless and the other is colored.
Thermochromic molecules undergo isomerization in response to temperature fluctuations.
Photochromic molecules undergo isomerization in response to UV light.
Posted in: Physical Changes