Saturday, January 30, 2010

What determines the colour of an organic dye?

This week I read most of chapter 4 of the book, Colour and Constitution of Organic Molecules by John Griffiths. I think it is a must-read for anyone working on dye molecules. It is at an elementary level and so accessible to both chemists and physicists, experimentalists and theorists. I fear much of the content has been forgotten or is unknown to many working on these materials, whether quantum chemists or biologists trying to find new molecules for fluorescent marker or people working on dye-sensitised solar cells.

Griffiths gives a nice discussion of resonance theory and then discusses its "failures", stating:
The apparent failure of resonance theory in these systems arises from the assumption that only low energy resonance forms need to be considered as contributing to the ground and first excited states.
Indeed, work by Seth Olsen and I (mostly Seth) shows for methine dyes (including flourescent proteins) how to do this in a systematic manner.


  1. Schillerstoff ... Anyone know the history behind this stilbene.

    I have a reference in Arch Pathol Vol 95, 1973, 37-41. Gold H: Vom "Schillerstoff" zum "Weisser als Weiss". SVF Fachorgan 19:416-419.
    Does anyone have a copy?

    I am rooting around among the dyes that stain amyloids and found this link to "The Blue Whitener" Where does Schiller fit in with this?

  2. it's aesculin. the name comes from the german "schillern",which means some sort of opalescence, due to the dual color (yellow + blue) that can be seen in solution due to the blue fluorescence and the yellow color.