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

Abstract

Former work has improved the energy storage capacity of the dihydroazulene/vinylheptafulvene photo/thermoswitch by substitution with NH and NO 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.

Computational and Experimental Evidence of Two Competing Thermal Electrocyclization Pathways for Vinylheptafulvene

“…Earlier computational work includes a single TS, which we identify as the Disrot‐TS . Our identification of these two TSs has resulted in inclusion of these in the theoretical work in a number of recent publications …”

“…[9,25,26] Our identification of these two TSs has resulted in inclusion of these in the theoretical work in an umber of recent publications. [22,[27][28][29] The Gibbs energy differences between the lowest energy VHF conformer and TS, DG VHF!TS ,a re shown in Figure 2f or each investigated DHA/VHF system in vacuum and the four solvents (benzene, tetrahydrofuran, acetone, and acetonitrile). No diastereoisomerse xist for CN-DHA/CN-VHF and, therefore, CN-VHFs imply ring-closes to form CN-DHAv ia the lowestenergy TS, in this case the CN-Conrot-TS in all investigated solvents (Figure 2, left panel).…”

Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity

“…All calculations were performed in Gaussian 16 using density functional theory (DFT) and its time‐dependent analogue (TD‐DFT). We employed the hybrid meta‐GGA functional M06‐2X and the Pople style 6‐311+G(d) basis set as deemed appropriate in previous benchmark studies and work on similar systems . Furthermore, the IEF‐PCM continuum solvation model was used to describe polarization effects of a surrounding dielectric medium resembling EtOH through a static and an optical dielectric constant (ϵ st =24.85 and ϵ op =1.853, respectively).…”

Front Cover: Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity (ChemPhotoChem 8/2019)

“…We employed the hybrid meta-GGA functional M06-2X 53,54 and the Pople style 6-311+G(d) basis set [55][56][57] as deemed appropriate in previous benchmark studies 11,58 and work on similar systems. 22,[59][60][61] Furthermore, the IEF-PCM continuum solvation model 62,63 was used to describe polarization effects of a surrounding dielectric medium resembling EtOH through a static and an optical dielectric constant ( st = 24.85 and op = 1.853, respectively). Structures resulting from geometry optimizations were confirmed as true energy minima or transition states (zerothor first-order saddle points, respectively) through harmonic frequency analyses (having zero or a single imaginary frequency, respectively).…”