Chemo-Selective Transformation of Anthracene Derivative within Water-Soluble Coordination Cages Having Different Cavities

Coordination cages with specific properties and functionalities are utilized as reaction vessels for the desired chemical transformation of substrates. The symmetry and inherent cavity of coordination cages can influence the host-guest interactions and the reaction outcome in their confined space. However, the impact of the cage shape on different transformations remains unclear. In this chapter, we report the chemo-selective transformation of anthracene derivative using three geometrically distinct Pd₆ cages (CC2, CC3, and CC4). Photoirradiation of 9-bromoanthracene (G3) in the distorted double-square cage (CC2) yields anthracene-9,10-dione, while the known double-square cage (CC3) forms a [4 + 4] cycloaddition product. The same reaction in a known Pd₆ bowl-shaped cage (CC4) resulted in the oxidized product. Through a combination of experimental and computational studies, we demonstrate that the shape and cavity size of coordination cages can significantly influence the reaction pathways of the encapsulated anthracene derivative, leading to chemo-selectivity. Furthermore, we observe that the encapsulation of 9-bromoanthracene (G3) in the cage cavities (CC2 and CC4) leads to a significant enhancement in the rate of photooxidation of G3. This work underscores the versatility of water-soluble coordination cages as reaction vessels in synthetic chemistry, offering interesting avenues for chemo-selective chemical transformation.