Atypical Structural and [pi]-Electron Features of a Melanin Polymer That Lead to Superior Free-Radical-Scavenging Properties

The black we wear: Why nature selected 5,6-dihydroxyindole-2-carboxylic acid (DHICA) to synthesize (photo)protective eumelanin pigments is an enigma. Synthetic DHICA eumelanin has now been shown to be a highly efficient free-radical scavenger in the solid state, which is due to a conformationally interrupted π-electron network associated with atypical optical, paramagnetic, and aggregation properties.