Decoding the infrared signatures of pyramidal carbons in graphenic molecular nanostructures of interstellar origin

In fullerenization chemistry, the whittling of carbon units from graphenic all-hexagon systems drives the local structural transformation from a sp2-hybridized composition into a pyramidal-like carbon composition. This chemical process recently observed in real time is believed to involve the self-sculpting action of local strain forces leading to fullerene growth. Here, an atomistic structural representation of this process is elaborated and correlated with spectral simulations of graphenic molecular models in varied curvature–strain stages that allows uncovering the fingerprint of fullerenization. Application of this fingerprint to Infrared Space Observatory data reveals that interstellar graphenic matter undergoes fullerenization, leading to the formation of strained fullerene-like 3D species. This suggests an evolutionary chemical interrelation between forms of strained molecular nanostructures, and includes bowls, cones and cages. These results offer a valuable platform in all-carbon chemistry useful to advance our understanding of both experimental and interstellar sp2-carbon nanostructures.