Density Functional Theory Study of the Solvent Effects on Systematically Substituted Dihydroazulene/Vinylheptafulvene Systems: Improving the Capability of Molecular Energy Storage

Former work has improved the energy storage capacity of the dihydroazulene/vinylheptafulvene photo/thermoswitch by substitution with NH<sub>2</sub> and NO<sub>2</sub> in vacuum. This work extends the former by investigating the solvent effects systematically using cyclohexane, toluene, dichloromethane, ethanol, and acetonitrile and comparing them with the inclusion of vacuum calculations. The investigation includes more than 8000 calculations using density functional theory for comparison of energy storage capacities, activation energies for the thermal conversion of vinylheptafulvene to dihydroazulene, and UV–Vis absorption spectra. We thereby establish design and solvent guidelines in order to obtain an optimal performance of the dihydroazulene/vinylheptafulvene system for use in a solar energy harvesting and storing device.