# Designing Molecular Solar Thermal Systems Based on the Paternò–Büchi Reaction Coupled to Enzymatic Energy Release

## TL;DR

This paper proposes a new molecular solar thermal system using the Paternò–Büchi reaction and enzymatic energy release to improve energy storage density and efficiency.

## Contribution

The study introduces a novel molecular solar thermal system with higher storage density and an enzymatic method for energy release.

## Key findings

- The Paternò–Büchi reaction offers a higher energy storage density than the norbornadiene–quadricyclane system.
- Enzymatic reversion is a sustainable method for releasing stored energy in the proposed system.
- Computational analysis reveals the effects of substitution patterns on the system's photoreactivity and energy storage.

## Abstract

Molecular solar thermal systems are attracting considerable attention as an alternative to conventional batteries for storing chemical energy, making it possible to use sunlight as external storage input, while releasing the stored energy as heat. Despite such interest, acceptable results are obtained only by modifying the norbornadiene–quadricyclane system, still leaving key issues unsolved. Here, a full storage‐release molecular solar thermal systems cycle based on the Paternò–Büchi reaction is designed, potentially offering a class of compounds with a significantly higher storage density than norbornadiene–quadricyclane. Based on the experimental evidence concerning the viability of their synthesis and photoreactivity, those compounds are repurposed by computationally elucidating the substitution pattern effects on low‐energy isomer's light absorption, followed by high‐energy isomer's photoproduction, including singlet and triplet states involved by the Paternò–Büchi type of reactivity. The thermal conversion back to the initial isomer to release the stored energy is also studied, including a sustainable option by taking advantage of enzymatic activity.

Molecular solar thermal systems urge for innovative building blocks to increase their present limits in storage density and light activation window. Here, a complete computational study of loading and unloading mechanisms for an experimentally inspired system based on the Paternò–Büchi reaction is presented. Unconventional enzymatic reversion is proposed to release the stored energy.© 2025 WILEY‐VCH GmbH