Making molecules in crystals

Controlling reactions in crystalline solids provides new opportunities in synthetic chemistry and materials science. Much effort has been devoted to using non-covalent interactions (e.g., hydrogen bonding, halogen bonding and metal coordination) to direct the formation of covalent bonds in photoactive solids. In this case, use of small organic molecules (e.g., resorcinols) as templates to assemble reactants (i.e., olefins) in a desired geometry for a [2+2] photodimerization continues to draw research interest. While tremendous progress has been made in the field during the past two decades, additional studies are essential to expand the toolbox of non-covalent interactions to enable the design and synthesis of functional solid materials as well as structurally diverse molecular building blocks. Moreover, achieving single-crystal-to-single-crystal (SCSC) reactivity and rapid functional group diversification of the photoproduct remains challenging.