Isolation of elusive cyclobutane ligands via a template-assisted photochemical [2 + 2] cycloaddition reaction and their utility in engineering crystalline solids

Abstract

Solid-state photochemical [2 + 2] cycloaddition reaction is one of the promising routes to isolate highly strained cyclobutane derivatives, which may otherwise be very difficult to obtain via conventional synthetic methodology. Various methods have been developed to align the olefins in crystalline materials for the fabrication of cyclobutane derivatives. However, the separation of cyclobutane ligands from the photo-product has not been much explored. In this highlight, a variety of functional cyclobutane ligands (62 compounds), isolated from their photoproducts have been described and categorized according to their synthetic strategies. The utilization of those functional cyclobutane compounds as ligands for the construction of topological networks, either in the form of cocrystals or coordination polymers (CPs), is described.