Excited State Chemistry of Capsular Assemblies in Aqueous Solution and on Silica Surfaces

Synthesis and encapsulation properties of two new water-soluble resorcinol-capped organic cavitands (tetra acid and octa acid; RTA and ROA) are reported in this Letter. Organic guest molecules template the formation of capsular assembly of the above cavitands in water. Depending upon the guest, either 1:2 (guest to host) or 2:2 capsular assemblies were formed. The excited state properties of guests such as anthracene, camphorthione, and 4,4′-dimethyl benzil were distinctly different within a capsular assembly from those when they were free in a solution. Importantly, the host–guest complexes of the above two hosts (RTA and ROA) as well as octa acid (OA) could be transferred to a silica surface. The excited state behavior of host–guest assemblies on silica surface resembled that in solution. The high cage effect in the decarbonylation products and high yield of rearrangement product obtained upon photolysis of 1-phenyl-3-tolyl-2-propanone included within RTA, ROA, and OA both in solution and on silica surf...