I’m looking for an organic* material – a killer dye – with the following properties.
killer dye

Must have

  • Nice price. In other words, not something fancy from the latest issue of JACS.
  • Commercial availability and in stock. Not in “8-12 weeks.”
  • Chemical INSTABILITY towards light. Preferably at a defined wavelength. Say 254 nm; not in the visible spectrum. This is the most important feature. The material should break down to a colorless state under controllable conditions.

Nice to have

  • Reasonable stability under ambient conditions (excluding light). Relative inertness towards air and moisture.
  • Reversibility. If the discolored dye could be reversed back to its colored state, we are talking. In the best of worlds, using light at another defined wavelength. Optionally, using a second chemical component such as an oxidant or reductant. Or some other mechanism. I’m open to suggestions.

Irrelevant

  • Color. Not white or pale yellow. Anything else goes.
  • Solubility.
  • Molecular weight. Both polymers and small molecules are OK.

Caveat

  • I can’t tell you what it’s for. Not now, and not later. That’s just life in industry. Sorry.

If a material springs to mind, I’m all ears! Thanks a million.

* N.B. I’m using the old definition of “organic.” The one that refers to chemistry.

 

11 Responses to Need a killer dye

  1. Chemjobber says:

    Since you seem to have the makings of a RFQ here, seems to me that you need to talk about your willingness to spend money (either for a finished product/starting materials) and how much you need.

    • Chemjobber says:

      Aaaaand I am an idiot.

    • drfreddy says:

      In-house project. Privately funded. So, a rather tight budget for a first prototype. A couple of hundred US for a couple of grams, tops? Preferably less, since the active material will be, in all likelihood, the most inexpensive part in whatever it is we are trying to accomplish.

  2. Steve says:

    What about s-tetrazine? It’s a stable red solid under ambient conditions, which is capable of undergoing photochemical fragmentation at 327 nm to give 2 HCN molecules + nitrogen gas. King, D. S.; Denny, C. T.; Hochstrasser, R. M.; Smith, A. B., III. J. Am. Chem. Soc. 1977, 99, 271. Substituents can be added to the 3 and 6 positions to s-tetrazine and retain similar photochemical properties within low temperature crystals, the condensed phase or gas phase.

    Clearly the photochemistry is not reversible, however 3,6-sulfur substituted tetrazines can be reduced with Pd/C to generate dihydrotetrazine, shifting the solution from red to colorless and upon exposure to air, dihydrotetrazine will re-oxidize back to the tetrazine (red). Courter, J. R.; Abdo, M.; Brown, S. P.; Tucker, M. J.; Hochstrasser, R. M.; Smith, A. B., III J. Org. Chem. 2014, 79, 759.

    s-Tetrazine is a quite interesting molecule—check it out.

  3. drfreddy says:

    Also, many thanks to this from Twitter. “Photoswitch” seems to be the droid I’m looking for.

  4. milkshake says:

    I would use some super-cheap super strong fluorescent dye – i.e. fluorescein, eosin or rhodamine, then hit it with UV light right at the dye excitation maximum until it photo-bleaches. Just what the cell biologists are trying to avoid, when watching their fluorescent-labeled cell slides under microscope…

  5. Marek says:

    Hey!
    At Oxford in my first year we made this compound:
    2-(2,4-Dinitrobenzyl)pyridine
    – simple dinitration from a commercially available (would guess relatively cheap) starting material and changes color on light from lightly yellow to dark blue if i remember correctly. Might be worth looking into! 🙂
    Hope this helps!
    Marek

    • drfreddy says:

      Interesting. Any idea what the blue degradation product might be? I like pyridines, and I like TNT 🙂 This has a little of both. Your structure isn’t very dye-ish though, and I can’t figure out what light would do to it.

      Blue as in “a blue tone”, or the really deep blue you see in for example ketyl radicals (benzophenone+sodium or low-valent titanium in the McMurry coupling)?

  6. Dr Kirkham says:

    Ferrocenyl azobenzene derivative may meet most of your requirements,except you need to do the diazotization yourself.

    Another option you may like to look at is the classic Spiropyran/spirooxazine system. There are a huge number of potential compounds for this system.

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