Make Blue Smash-Glow Crystals (Triboluminescence Demonstration)


Uploaded by NurdRage on 29.08.2012

Transcript:
Warning: This experiment uses toxic, volatile and carcinogenic chemicals.
This should be performed with gloves in a fume hood.
Greetings fellow nerds.
In a previous video we made red smash glow crystals.
In this video we’re going to make crystals that glow a blue color when smashed.
First get 121mg of copper thiocyanate and 262mg of triphenylphosphine.
Then add to it 5 to 10mL of pyridine.
I’m using 10mL of pyridine for clarity but you can use 5mL.
Shake it up and then gently heat it with occasional shaking to until everything is dissolved.
What we’re making is a coordination complex with copper in the center
surrounded by two pyridines, a triphenylphosphine and a thiocyanate ligand.
Once everything is dissolved turn off the heat and leave it for a day or two to evaporate and crystalize.
Don’t let it completely dry out since we don’t want the impurities to solidify as well.
Here we are with most of the pyridine evaporated but not touching the crystals.
Now use a pipette and remove all the dirty pyridine.
Then wash the crystals a few times with toluene until they are clean.
Remove all the toluene and let the crystals dry.
And here we have it dry crystals of triphenylphosphinebis(pyridine)thiocyanatocopper(I).
Or as I like to call them blue smash-glow crystals.
Under ultraviolet light these crystals exhibit a nice blue fluorescence.
This is the same color it will glow when smashed.
While not quite as brilliant as the original red smash glow crystals, it's still quite bright.
Now for their coolest property.
Under low light take a crystal with a spatula and grind it against the wall of the vial.
As it’s crushed it will flash blue light.
It’s not sparking or generating heat but it’s converting mechanical energy directly into light.
What’s happening is because the individual molecules are not centrosymmetric
when the crystal is broken up the surfaces possess an uneven charge distribution.
The charges recombine and release energy
that excite the fluorescent property of the crystals and produce the light we see,
which as expected is the same emission wavelength as fluorescence emission.
Eventually once the crystals are completely ground into a powder they will stop working.
But they can be recrystallized from pyridine for further use.
So that was blue smash glow crystals.
Thanks for watching.
The idea for this video came from this article in the journal of chemical education.