One of the most promising MOST systems is the norbornadiene/quadricyclane (NBD/QC) couple (Figure ), which was introduced as a potential MOST system in 1961 by Dauben and Cargill, although the isomerization reaction of a NBD/QC dicarboxylic acid system was already observed in 1954 by Cristol and Snell. Since then, the system has been extensively studied due to its high energy density of almost 1 MJ/kg, which is estimated to be the fundamental upper limit of MOST systems and comparable to Li-ion batteries. However, the absorption spectrum of NBD lies in the UV region with absorption onset at 267 nm, and has therefore no overlap with the spectrum of solar radiation. Several studies have shown that it is possible to obtain a large redshift in the absorption spectrum and better quantum yield, but at the expense of a decrease in the energy density due to the added weight of the chromophore. For example, in a recent perspective Orrego-Hernández et al. highlight seven examples of NBD systems with absorption onsets of 362-466 nm, but energy densities of 0.10-0.56 MJ/kg -compared to 0.97 MJ/kg for unsubstituted NBD. Furthermore, four of the seven molecules have half-lives of a week or less, which make them unsuitable for long-term energy storage.