“…To date, impressive advances have been made in mastering various nanodevices, e.g., switches [ 1 , 2 ], sensors [ 3 , 4 , 5 , 6 ], catalytic agents [ 7 ], actuators [ 8 ], and logic gates [ 9 ]. Submicron-sized mechanical and electromechanical machines are also an important advance [ 10 , 11 , 12 , 13 , 14 ]. However, the design of molecular machines a few nanometers in size remains a challenge.…”