Candles that change color when their lit?  You probably thought I was going to add some metals to them and the flame would go from green to red to yellow etc., right?  Pffft.  Fuck that metal shit.  I’m an organic chemist and therefore I shun the use of metals – SHUN THEM.  SHUN THEM STRAIGHT TO HELL.  Unless I need to use one to do some reaction… then they’re welcome.  BUT THEN IT’S BACK TO SHUNNING!

A decidedly organic solution is to use the properties of fluorescence such that when the candle is lit it likewise lights up a fluorophore which, hopefully, is a different color than the flame or the wax surrounding it.  To accomplish this we need a few fundamental things:  1) An organic dye that isn’t too horribly toxic that doesn’t produce yellow/orange light when it fluoresces.  2) A medium (i.e. the wax) that is transparent and easy to work with. 3) a container within which you shall burn your mighty candle.

Above you see all three solutions (that I present for this little exercise).  I shall burn anthracene in GelWax inside a 20mL scintillation vial.  The first step is to melt your gelwax and add the anthracene, which I have
made up as a saturated toluene solution for easy adding pleasure.  After you melted your wax on a hotplate, you are free to add your toluene solution of anthracene.  You want to bubble off the toluene so that when you go and light up the candle you aren’t totally overwhelmed by stinky model-glue smell.

This process takes a minute, so you’ll want to be patient.  Once the bubbling stops, however, you can pour the waxy goodness into your vial with a wick positioned inside it. You can make clever use of your three pronged clamps by holding a wick that you presumably purchased at the same craft store that you found your wax at.  The drying process then must occur… and you wait and wait and wait.

Now, I’ve never made a candle in a little vial like this before and, after having done it, I recommend two things from this whole experiment.  One:  Don’t use 20mL vials.  They are too fucking small.  You’ll see below I had to break the rim off mine to keep the wick lit.  Two: don’t use anthracene.  Antrhacene is a pretty color and everything, but in reality you want something that is excited by yellow/orange light – not UV light, which (as it turns out) candles put out almost none of.  So, indeed, when I went to light this shit up I really got disappointed in that I saw no blue coming out of my vial – only after I shut the lights out and turned the exposure setting on my camera way the fuck up and then photoshopped the flame down so it didn’t look as lit up as an Englishman in Prague (limy bastards piss on everything) was I able to obtain the results below.  It’s certainly not a “naked-eye” thing.

It’s not spectacular.  What needs to happen is a different dye, specifically a red emitting dye that absorbs those pretty fire colors and the only one of which I know to be simple enough to make are squaraines, which simply involve refluxing squaric acid with N,N-dialkyl-aniline with some sieves.  Squaric acid can be pricey, so you’ll have to check with your boss if you want to purchase this shit.  As for me, I found a retailer on the intertubes that actually sells the shit to anyone.  The anline is cheap, no one will miss it.  Of course, if you have the dye just handy, that makes the whole thing that much simpler.  Turns out I have a dye on hand (though not the magical squaraine) and in enormous quantities because another lab, which did research on this kind of shit, cleared out and we inherited their chemicals including a jar of “Cy5.5.”  Figuring one dye was as good as any other, I dissolved it up in good ol’ chloroform and tossed it into the molten wax.  I then dumped my hot load into a large bowl I purchased from the craft store and set the wick and let it sit for a while.  To summarize:

Anyway, after all that sitting and waiting for the fucking wax to solidify I ended up with a pretty awesome candle.  You can see the results below.  The dye appears green but sure enough it fluoresces red.  This will make an asskickity gift for someone who needs to be reminded HOW IMPORTANT I AM TO THE LAB and how awesome I am at the same time.  (I do *hearts* my boss but sometimes our “visions and directions” of how my research should go leads to tense relationships.  I like to think that by buying his affection like this I can remain in those good graces well after he starts reviewing my own future grants.)

Now that’s some pretty science right there.

Now, to cover my ass:  These candles are never to be lit outside of a properly constructed and certified fume hood.  Burning anthracene and aromatic compounds in general is a bad idea and produces a gross black flame of cancer.  Toluene smells bad and that green candle was made with more chloroform than I’d like to admit. They’re (probably) perfectly safe to set on a shelf and enjoy the fuck out of; however, I take no responsibility for your future cancers.  (I have it on good authority that the long wavelength dyes don’t last too long on the shelf – even in wax.)