cep - 8-4-2011 at 11:48
Hi Guys,
I'm just kind of stabbing in the dark here... I don't know if this is the correct topics page, or even the correct kind of forum on which to ask this
question. Anyway, I need to fluorescently color a siloxane oil. I tried using Fluorol Yellow 088 from Sigma, but it photobleached very quickly (lost
half its fluorescent intensity in less than 5s). My next candidate is Sudan Red, but I haven't been able to find any information on its
photostability. Literature searches are not very helpful.
So, all that being said, can anyone help me out with some info on photostabilities of hydrophobic dyes? Any information, general or specific, would
be appreciated. Thank you!
GreenD - 8-4-2011 at 13:54
My thinking is you're going to have to find a reactive dye that forms a complex or compound with your siloxane oil.
Most dyes that are brightly colored come from metal complexes. These complexes tend to be hydrophilic and are usually aqueous. There are ways around
this though, making the compound extensively oily and hydrophobic with ligands can allow them to be hydrophobic.
What I would do is buy some dyes that are meant to stain polyester - these are the dyes that professional companies make whole-colored T-shirts with.
See if those work. These will be essential inert to the sun, as can be seen by the t-shirt you are wearing.
Other dyes are going to be EXCEPTIONALLY reactive to sunlight, as they are undoubtedbly large, conjugated molecules, or have metal ligands (which are
also going to be easily excited in the UV range).
Good luck!
Ozone - 8-4-2011 at 19:33
Holy cow. What sort of source are you using that will photobleach things in 5s? The Sudan dyes are pretty stable; it's my guess that they might last
for a while...>5s, I suspect. No dye which fluoresces will be totally exempt from photobleaching. For that, you could use quantum dots (CdSe, for
example), but they are surprisingly tricky to work with.
Cheers,
O3
[edit] oleic acid-capped CdSe would be a good solution--very hydrophobic and easy to make.
[Edited on 9-4-2011 by Ozone]