Simultaneous Optimization of Both Electrocyclization and Cycloreversion Reactions of Diarylethene Photoswitches for Solar-Energy Storage

Abstract

A popular approach to developing molecular solutions for solar-energy storage is based on exploiting the reactions of molecular photoswitches. However, given that the reactions in question are usually the reverse of one another, it becomes imperative to handle conflicting performance criteria when optimizing the reactions. Here, studying diarylethene switches operated by electrocyclization (for storing the solar energy) and cycloreversion (for releasing the solar energy) reactions, we show that these processes can be made to simultaneously exhibit the desired characteristics by introducing a tricyclic rather than monocyclic π-linker as the bridge between the two aryl units. Specifically, we perform quantum chemical calculations to demonstrate that such a scenario is realizable by tailoring, using aromaticity, certain parts of the tricyclic structure for electrocyclization and other parts for cycloreversion. Furthermore, employing this strategy, we identify several diarylethene switches, each with their own unique tricyclic π-linker, that concurrently meet key performance criteria like large energy-storage densities and long energy-storage times. Accordingly, we conclude that there appears to be considerable structural flexibility in implementing the ideas for efficient diarylethene-based solar-energy storage put forth in this work.