Dry-vortex grinding facilitates a [2 + 2] cycloaddition reaction that triggers a cascade-like reaction that improves the yield under substoichiometric conditions†

The ability to achieve a series of photoreactive solids using dry-vortex grinding that contains trans-1,2-bis(2-pyridyl)ethylene along with 2,4,6-trifluorophenol at different molar ratios is reported. In all cases, mechanochemical grinding generates a three-component hydrogen-bonded co-crystal that undergoes a [2 + 2] cycloaddition reaction. Curiously, the solids formed with a substoichiometric ratio of the template also reached a nearly quantitative yield, since the formation of the photoproduct causes a cascade-like reaction within the solid which shifts the remaining reactant molecules into a suitable position to photoreact.