During recent decades, there have been great scientific and technological progress in solar energy harvesting in the area’s of e.g. photovoltaics and solar thermal systems. Meanwhile, a challenge is the development of scalable energy systems for solar energy storage. In this context, one possible approach is to store solar energy is in the form of chemical bonds, referred to as molecular solar thermal energy storage (MOST). Norbornadiene (NBD) is one of the most promising candidate molecule since it photoisomerizes to form the metastable quadricyclane (QC) isomer. The reaction is reversible and the back-conversion can be triggered by e.g. a catalyst to release the energy as heat.<br/><br/>However, for the NBD-QC system to be efficient in MOST applications several requirements have to be fulfilled and a major task is to obtain good solar spectrum match but at the same time keep the half-lives long of the quadricyclanes. In addition, high storage densities and quantitative conversion between NBD and QC is needed. A successful strategy towards solar spectrum match is to decorate NBD with electron donating and accepting groups at one of the double bonds. Consequently, an efficient synthetic protocol is required and NBD substituted with halogens serves as a great handle for further functionalization via cross coupling reaction.<br/><br/>Throughout this protocol a series of NBD with cyano acceptor and ethynyl-substituted aromatic donor groups were synthesized, leading to good solar spectrum match with absorption onset up to 456 nm, high storage densities (369-629 kJ/Kg), quantitative conversion and improved life times compared to our previous candidates.

Norbornadiene - quadricyclane systems for molecular solar thermal energy storage

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.