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/vinyl- heptafulvene photo-/thermoswitch by substitution with NH 2 and NO 2 in vacuum. This work extends the former by investigating the solvent effects systematically using cyclo- hexane, toluene, dichloromethane, ethanol, and acetonitrile and comparing them with the inclusion of vacuum calculations. The investigation includes more than 8000 cal- culations 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.