Cavity-based applications of metallo-supramolecular coordination cages (MSCCs)

The microenvironment within self-assembled supramolecular coordination cages (SCCs) inaugurates a new phase of chemistry other than the conventional solid, liquid and gaseous phases. The rational design and ease of synthesis of self-assembled architectures have received tremendous attention mainly in the field of supramolecular chemistry. The structural transition from 2-D metallacycles to 3-D metallacages has led to better encapsulation and enhanced cavity effects, like restricted substrate motion, desolvation of the substrate and covalent binding of the transition state etc. Metal-mediated self-assemblies, principally known as metallo-supramolecular coordination cages (MSCCs), form a separate class of SCCs with unique chemical phenomena inside the cavities. The aesthetic structural diversity of MSCCs obtained from the rational choice of metal knots and organic linkers renders designable and programmable architectures. This review presents cavity-based applications of these MSCCs, such as molecular recognition and separation, stabilization of reactive species by encapsulation, as drug-delivery systems and as “molecular flasks” to foster reactions with unprecedented results. The objective of this review is to inspire and pave the way for researchers working in this field to design more advanced MSCCs and gain deep insight into cavity effects.