Achieving a series of solid-state [2 + 2] cycloaddition reactions involving 1,2-bis(2-pyridyl)ethylene within halogen-bonded co-crystals

Abstract

The solid-state [2 + 2] cycloaddition reaction of trans-1,2-bis(2-pyridyl)ethylene through both co-crystallization and mechanical grinding is reported. The photoreaction is achieved by using iodoperchlorobenzene as a molecular template. The co-crystal is sustained primarily by I⋯N halogen bonds and homogeneous face-to-face π–π stacking interactions. The combination of these non-covalent forces ultimately places the reactant in a suitable position to photoreact. In addition, a pair of photoreactive solids were also achieved through a solvent-free mechanical grinding approach with similar yields.