Almost nine decades since it was first inferred, the zinc complex of the tripyrrindione pigment makes its debut as a fluorescent radical. The tripyrrolic framework, which characterizes several heme metabolites, features a delocalized unpaired spin and undergoes one-electron redox chemistry. The paramagnetic Zn(II) complex thus joins a small group of stable radicals that are emissive at room temperature. (Cover art by Debra Bowles, BioCommunications, The University of Arizona) https://pubs.acs.org/toc/inocaj/57/24
