Long?Term Energy Storage Systems Based on the Dihydroazulene/Vinylheptafulvene Photo?/Thermoswitch

The dihydroazulene/vinylheptafulvene (DHA/VHF) couple presents a photo-/thermo-switch that has attracted interest for the development of molecular solar thermal energy storage systems. Here we present synthesis and optical as well switching properties DHA derivatives incorporating alkyne norbornadiene (NBD) substituents at position C2. corresponding VHF isomers exhibited remarkably long lifetimes. Thus, VHF-to-DHA back-reaction half-life derivative with phenylethynyl substituent was 22 days in acetonitrile room temperature, while reference compound having phenyl is around 3.5 h under same conditions. This finding particularly attractive quest long-term systems, considering limited enhancement weight maintenance good quantum yield photoisomerization. Moreover, from an NBD compound, used precursor DHA-NBD dyad, estimated radical-stabilizing influence C(Me)=C(CN) 2 substituent.