Topochemistry Meets Supramolecular Chemistry: Opportunities for Targeted Organic Synthesis in Molecular Crystals

Abstract

A milestone of crystal engineering has been the topochemical control of reactivity in the crystalline solid-state through the judicious usage of noncovalent interactions. Specifically, since the pioneering studies by Schmidt and co-workers who postulated the geometrical conditions of single crystals to act as a confined media for alkenes to undergo [2 + 2]-photocycloadditions, many recent supramolecular strategies have expanded and facilitated the topochemical control of reactivity. Supramolecular control of reactivity in confined crystalline media is exemplified using supramolecular templates or “shepherds”, that facilitate the positioning of alkenes into a suitable geometry for [2 + 2]-photocycloadditions. In this monograph, we explore selected examples of supramolecular templating of [2 + 2]-photocycloadditions within the last decade that rely on diverse supramolecular interactions. The advances in topochemical control of reactivity through supramolecular chemistry are expressed in the synthesis of unique yet varied cyclobutane-based organic architectures, which are important building blocks for pharmaceutics and high-dimensional complexes.

Sunlight‐Induced In Situ Isomerization of Both Ligands in a Mixed‐Ligand Coordination Polymer: From Photosalient to Photoinert Crystals

“…On the other hand, [2 + 2] cycloaddition reaction in CPs under light-illumination (UV or sunlight) is well studied by Vittal, MacGillivray, Naumov and few other groups along with our group. [22][23][24][25][26] In this case, systematic packing of olefinic C=C bonds of a compound after following the Schmidt's topochemical principle undergoes photodimerization in a singlecrystal to single-crystal (SCSC) or crystal to crystal manner. One of the first mechanical effects based on [2 + 2] dimerization was reported by Naumov group in 2010.…”