0
$\begingroup$

Context: a retinal molecule the isomerizes from all-trans to 13-cis form, then "reisomerizes thermally".

I tried googling it but couldn't find a simple, straightforward explanation.

$\endgroup$
4
$\begingroup$

The term "thermally" is used here to contrast with a photochemical isomerization. In the chemistry of vision, 11-cis retinal absorbs light and is isomerized to the all-trans isomer. This is a photochemical process because it involves the absorption of a photon to promote one electron into an antibonding orbital. In this excited state, the geometry can rearrange to the more stable all-trans form before the electron relaxes back to the ground state.

In a "thermal" process, no photons are absorbed, no electrons are promoted, and no excited states are needed. The molecule takes advantage of ambient or supplied kinetic energy to reorganize.

$\endgroup$
0
$\begingroup$

In photochemical isomerization absorbed light is responsible for conversion of cis to trans where as in thermal isomerization molecule uses its own thermal energy where molecules donot need to absorb photos .In addition no excitation takes place.

$\endgroup$
  • 2
    $\begingroup$ That's exactly what the accepted answer says, please elaborate further to make your answer stand out. Welcome to the site! $\endgroup$ – William R. Ebenezer Jul 10 at 4:09

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.