It’s time for a nod to one of my favorite chemistry-themed YouTube channels, NurdRage. NurdRage’s channel is basically a laundry list of awesome, little-known chemistry experiments…with a creepy yet soothing voice-changer voice to boot. One of his recent videos is especially cool: he synthesizes blue triboluminescent crystals from copper thiocyanate, pyridine, and PPh3, then grinds them up. The experiment is based on a recent JCE article from Marchetti et al. The reaction itself is straightfoward to perform: mix everything up, heat to dissolve, wait for cystallization, and wash! The copper salt, pyridine, and triphenylphosphine react to form the coordination complex (SCN)Cu(py)2(PPh3). Grinding of the crystals produces a stunning blue light.
NurdRage’s explanation of triboluminescence (the direct transduction of mechanical energy to light) is clear and concise—check it out below! Long story short, charge separation occurs in the crystal upon mechanical agitation, and recombination of the charges produces a blue light.