This reaction shimmers with a purple hue thanks to chromium(III) chloride (in a suspension, top; in its solid form, bottom). David Zigler’s lab at California Polytechnic State University set up the reaction as part of their work on inorganic photochemistry. The chemists placed CrCl3 in a flask with ethanol and 1,10-phenanthroline, a ligand that binds to chromium to make a green metal complex. The researchers later added other ligands to the green complex to make photosensitizers, molecules that trigger chemical reactions when they absorb light.
Credit: David Zigler (top), Ben Mills/Wikimedia Commons (bottom)
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