| Great strides in the synthetic accessibility of donor-acceptor mechanically interlocked molecules have been made by the application of highly efficient and ultramild chemical transformations during their template-directed synthesis. These new departures in synthesis have indeed played a transformative role in that more complex, higher-order, and functional architectures -- once only a dream -- are now comfortably within reach. Specifically, the formation of mechanical bonds in [2]-, [3]-, and [4]rotaxanes and in [2]- and [3]catenanes has become ever easier through the use of the Cu+-catalyzed azide-alkyne cycloaddition and the Cu2+-catalyzed Eglinton oxidative acetylenic homocoupling. The unique features of donor-acceptor mechanically interlocked molecules -- including dynamic mechanical bonds which lend great structural and translational freedom, as well as the ability to stimulate structural rearrangements through redox events -- predisposes them towards working as molecular machinery in functional materials and devices. Their increased accessibility, combined with the application of such mild and efficient processes for use in surface patterning techniques, bodes well for strategies seeking to interface molecular machines and surfaces in the shape of working devices. The development of such synthetic methods for high yielding rotaxane and catenane syntheses, as well as finely resolved surface patterning techniques is featured. Additionally, the unique workings of two electrochemically switchable catenanes borne out of these synthetic protocols are presented. |
