Hydrogen bonding mediated control of photochemical reaction is highlighted with an eye towards the development of BrØnsted Acid mediated photocatalysis.

Photodegradable, recyclable, and renewable, crosslinked polymers from bioresources show promise towards developing a sustainable strategy to address the issue of plastics degradability and recyclability. Photo processes are not widely exploited for upcycling polymers in spite of the potential to have spatial and temporal control of the degradation in addition to being a green process. In this report we highlight a methodology in which biomass-derived crosslinked polymers can be programmed to degrade at � 300 nm with � 60 % recovery of the monomer. The recovered monomer was recycled back to the crosslinked polymer.

This account highlights the role of restricted bond rotations to influence excited state reactivity of organic molecules. It highlights photochemical reactivity of various organic molecules and the design strategies that could be exploited by chemists to utilize restricted bond rotations to uncover new excited state reactivity and achieve selectivity.

A phototunable receptor binds to anions in one of its photoisomeric forms via CH⋯X interaction.

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