Light-driven exchange between extended and contracted lasso-like isomers of a bistable [1] rotaxane

The synthesis of a set of benzylic amide [1]rotaxanes via a self-templating clipping approach is described. This methodology supposes the 1 + 1 coupling of isophthaloyl dichloride with an acyclic diamine precursor incorporating a templating arm. The structure of the threaded compounds was determined both in solution and in the solid state. The conversion into the corresponding unthreaded isomers, also obtained by deslipping of [2]rotaxane models, was evaluated in competitive and non-competitive hydrogen-bonding solvents. The switch of the extended and contracted lasso-like isomers of a bistable [1]rotaxane by an olefin isomerization promoted by UV light irradiation was also accomplished and their ring positional integrity was examined.