A Molecular Machine Directs the Synthesis of a Rotaxane

Preorganization by assembly or templating strategies is frequently used in the synthesis of rotaxanes. While these approaches have led to complex interlocked molecules, they are often limited by strict compositional requirements of templates and starting materials. Here, we use a molecular machine to direct the synthesis of a rotaxane by active shaping of starting materials through mechanical winding. Light induced rotation of a molecular motor actively winds a molecular strand around an axle, forming discrete, thermodynamically disfavored crossings between these two parts. Covalent capture preserves the kinetically stable entanglements, transforming the strand into a macrocycle that is subsequently released and mechanically trapped on the axle, yielding a rotaxane. Our machine-directed strategy pioneers a new way of synthesizing rotaxanes by active mechanical shaping of molecular building blocks, enabling access to interlocked architectures beyond the reach of traditional assembly and templating approaches.