Gold on Carbon Catalyzed Conversion of Quadricyclane to Norbornadiene

Journal article, 2026

The norbornadiene (NBD)-quadricyclane (QC) photoswitch system has emerged as a promising candidate for molecular solar thermal (MOST) energy storage, enabling solar energy capture and on-demand heat release. A critical step in these systems is the catalytic back-conversion of QC to NBD, which governs energy release efficiency. While noble metal catalysts have previously demonstrated activity, their long-term stability and scalability remain major challenges. In this study, we introduce a heterogeneous catalyst composed of 2-3 nm gold nanoparticles supported on Vulcan carbon (Au@Vulcan) for QC to NBD conversion. Three different QC derivatives with distinct substitution motifs displayed efficient back-conversion, as confirmed by NMR and UV-vis spectroscopy. Mechanistic insights into the QC to NBD isomerization, obtained from density functional theory (DFT) calculations on a model gold trimer, revealed two viable pathways: a concerted mechanism and a single-electron transfer mediated route. ICP-MS stability tests indicated partial gold leaching, underscoring the need for improved anchoring strategies to enhance catalyst durability under specified reaction conditions. Together, these findings demonstrate both the catalytic potential and limitations of Au@Vulcan, providing a framework for the rational design of more durable, cost-effective MOST catalysts and guiding future development of NBD derivatives towards a fast, responsive energy release process.