Catalysis in Cyclodextrin-Based Unconventional Reaction Media: Recent Developments and Future Opportunities

During these last years, cyclodextrins (CDs) have greatly contributed to the development of innovative homogeneous or heterogeneous catalytic processes. More than simple molecular platforms aiming at designing new ligands or interfacial additives, CDs have been employed to generate unconventional reaction media such as supramolecular hydrogels or low melting mixtures (LMMs) capable of stabilizing active catalytic species. By using such alternative and unconventional media, high catalytic activities and selectivities were obtained in various transition metal catalytic reactions. The studied catalytic systems are easy to implement and allow for the remarkable stabilization of organometallic or metal nanoparticle catalysts. Interestingly, the size of metal nanoparticles can be finely tuned through confinement in the network of CD-based supramolecular hydrogels. Additionally, the catalysts can be recovered by a simple phase separation. The catalytic phase can be stored at room temperature under an air atmosphere in the solid state and reused as needed without significant loss of activity. Eventually, such CD-based catalytic systems greatly improve process safety. The present article intends to show the reader the very substantial progress that has recently been made in the field.