Abstract:

Molecular clips or tweezers are curved compounds with properties of self-assembly and host-guest recognition. These clips are capable of binding guests using various supramolecular interactions. They are designed with two ‘arms’ chosen for their inclination to “sandwich” a given guest. Most examples of resorcinarene-derived cavitand synthesis are symmetrical: the resorcinarene-derived deep cavitands either belong to the point groups C4 or C4v (four identical walls) or have one of their walls differentiated by a more elaborate synthesis (Cs symmetry). To date there exists no efficient synthetic methods to control the placement of two different cavitand walls A and B to generate all five possible combinations—A4, A3B, cis A2B2, trans A2B2, AB3, and B4—because the problem of synthesizing cis A2B2 and trans A2B2 in more than trace amounts has not been solved.2,3 We now present a new regioselective synthesis of the cis A2B2 isomer, which will complete the solution to this problem, and in so doing provide a new class of molecular clip or tweezer that is effectively a two-walled deep cavitand.