Metal-free photochemical hydrogen storage in aromatic compounds

[Display omitted] •Based on Baird́s rule, a new method for hydrogenating aromatic molecules by metal-free photochemical reaction is proposed.•This new reaction is feasible as a hydrogen storage procedure at low cost.•Hydrogen technology has become an important alternative for societies and pursued by chemists.•Hydrogenation of aromatic compounds are challenging chemical reactions due to the endergonic nature of the process.•A new reaction where the aromaticity itself is the driving force of hydrogen transfer is shown. Based on Baird́s rule, which states that the excited state of an aromatic compound is antiaromatic, a new method for hydrogenating aromatic molecules by metal-free photochemical reaction employing 1,4-cyclohexadiene (1,4-CHD) as hydrogen source is proposed. Here only light and 1,4-CHD are required to hydrogenate aromatic compounds without metal catalysts or temperature. The proposed mechanism is related to the reduction potential of the aromatic probes on their first triplet excited state. In such methodology, besides the non-aromatic character of the excited state, the aromatization of the hydrogen donor turns this reaction feasible as a hydrogen storage procedure at low cost, expanding the chemical interest for materials like graphene.