Rh-catalyzed mechanochemical transfer hydrogenation for the synthesis of periphery-hydrogenated polycyclic aromatic compounds

Hydrogenated nanographene has attracted attention as a new class of nanocarbon material owing to its potential applications in various research fields. However, the synthesis of periphery-hydrogenated nanographenes or polycyclic aromatic hydrocarbons (PAHs) is a significant challenge because of the harsh conditions and poor solubility of the starting materials. Conventional solution-state conditions require high-pressure hydrogen gas and lengthy reaction times. In this study, we developed a novel approach utilizing rhodium-catalyzed mechanochemical transfer hydrogenation, which enables hydrogenation without using hydrogen gas. Various hydrogenated PAHs were rapidly obtained using a simple protocol under ambient atmosphere and air, with one PAH showcasing intriguing properties such as aggregation-induced emission. Thus, the demonstrated mechanochemical hydrogenation method is expected to contribute to the rapid and efficient synthesis of a novel class of sp²/sp³-carbon-conjugated hydrocarbons.