Big challenges for tiny machines

An issue entitled 'Molecular Machines and Switches' was presented by Prof. Alberto Credi in honor of J. Fraser Stoddart, a Honorary Professor, with an aim to highlight key areas and directions in the field of molecular machines. Stoddart is one of the few chemists to have created a new field of organic chemistry, one in which the mechanical bond is a pre-eminent feature of molecular compounds. This issue, with six feature articles and ten full papers, will provide a quick and authorative look at the field of molecular machines and switches. Zink and co-workers show that bistable rotaxanes can be used to close and open nanopores on a mesoporous silica surface by moving the ring component closer to and away from the pore openings. Kaifer and co-workers use cucurbit[6]uril or cucurbit[7]uril as a host to give rise to the formation of stable wheel-on-an-axle inclusion complexes in aqueous solution. Flood, Jeppensen has synthesized a mechanically interlocked and self-complexing springlike molecular Ouroborousthat incorporates π-donor and π-acceptor units in this issue.