Temporal control of the host-guest properties of a calix[6]arene receptor by the use of a chemical fuel

The host−guest interaction of a 1,3,5- trisaminocalix[6]arene receptor with N-methylisoquinolinium trifluoromethanesulfonate (K(association) = 500 ± 30 M‾¹ in CD₂Cl₂) can be dissipatively driven by means of 2-cyano-2-(4'-chloro)-phenylpropanoic acid used as a convenient chemical fuel. When the fuel is added to a dichloromethane solution containing the above complex, the host is induced to immediately release the guest in the bulk solution. Consumption of the fuel allows the guest to be re-uptaken by the host. The operation can be satisfactorily reiterated with four subsequent additions of fuel, producing four successive release-reuptake cycles. The percentage of the guest temporarily released in the bulk solution by the host and the time required for the reuptake process can be finely regulated by varying the quantities of added fuel.