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Chemistry In Pictures

Chemistry in Pictures: Volcano in a bottle

by Manny I. Fox Morone
March 14, 2024

A flask sits in the dark illuminated by an ultraviolet light and contains a suspension with yellow fluorescent crystals of an aggregation-induced emissino material slowly forming inside. From the middle of the flask emerges a bubble, which forms a bright green cone as it rises.
Credit: Xiaolin Liu

Xiaolin Liu snapped this photo as an air bubble slowly rose through this flask of fluorescent crystals. Liu, who at the time was a PhD student in Ben Zhong Tang’s lab at the Hong Kong University of Science and Technology, noticed the intense color of the recrystallization process her labmate, Zhiyang Liu, was running. Zhiyang’s project centered on aggregation-induced emission (AIE) materials, compounds that fluoresce strongly only after they coalesce. What’s more, because the fluorescence color of this compound depends on its solvent environment, a distinct difference emerges between the polar dichloromethane at the bottom of this flask and the nonpolar hexanes in the middle and top. So as the bubble carried the crystals through the hexane layer, an eerie green cone emerged out of the fiery yellow. Xiaolin, who’s now a postdoc at the University of Illinois Urbana-Champaign, remembers thinking it looked like an oversaturated volcano on its own tiny island that was worthy of a photo—and a post on C&EN Chemistry on Pictures.

Submitted by Xiaolin Liu

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