Solar thermal fuels store light energy via photoisomerization of a chromophore to a metastable isomer. Upon reversion to the stable isomer, the difference in enthalpy between the metastable and stable isomers is released as heat, closing the molecular cycle of energy storage and release. Though largely abandoned decades ago, solar thermal fuels are now being reexamined in light of new strategies for increasing energy densities and storage lifetimes. In particular, one promising strategy that we have explored recently involves arranging chromophores on nanoscale templates. Successful development of such nanostructured solar thermal fuels demands an understanding of the challenges faced in previous efforts to photochemically generate strained organic structures as well as knowledge of physical organic chemistry concepts such as linear free energy relationships originating from the Hammond�Leffler postulate, a hypothesis correlating the energies and structures of stationary points on a potential energy surface. Critically, solar thermal fuel design also necessitates a deep understanding of the origins of these phenomena so that candidate chromophores and nanostructures with promising thermodynamic, kinetic, and photophysical properties may be identified and subsequently optimized within the context of closed-cycle solar energy storage. Beginning with a discussion of recent developments in solar thermal fuel design utilizing our nanostructure templating approach, I will highlight the fundamental photochemical and physical organic principles that play key roles in chromophore selection and supramolecular design, and discuss how the design process thus provides unique opportunities for educating students in these areas.

Back to basics: Teaching organic photochemistry and linear free energy relationships in solar thermal fuel design

247th National Meeting (2014)

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