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Chemistry In Pictures

Chemistry in Pictures: Water it down, turn it up

by Manny Morone
May 24, 2018


Eleven flasks in a line containing solution of the same dye with different solvents; the first glows orange, but the next five do not glow very much; the five flasks after that glow increasingly brighter.
Credit: Adam Henwood and Thorri Gunnlaugsson

These flasks all contain the same amount of a fluorescent napthalimide dye. Why aren’t they all glowing at the same intensity? Water. From left to right, the flasks contain increasing amounts of water. At first, upping the water content from 0% to 10%, and thus decreasing the amount of organic solvent, turns off the dye’s glow (first two flasks from left). Trinity College Dublin graduate student Adam Henwood and professor Thorri Gunnlaugsson designed this naphthalimide dye to form nanoparticles that glow even brighter than the free-floating molecules. As the water content rises to 95% (far right), the hydrophobic dye molecules bunch up to form these particles and the flask’s glow intensifies.

Submitted by Adam Henwood and Thorri Gunnlaugsson

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