Mechanically Interlocked Molecules Assembled by π-π Recognition

The beauty and utility of interlocked architectures have been making their way relentlessly into chemistry in the form of mechanically interlocked molecules (MIMs) for almost half a century now. Few would challenge the assertion that the emergence of template-directed synthetic protocols has aided and abetted the facile and efficient construction of MIMs compared with the statistical approaches employed while the field was still in its infancy. To date, a panoply of MIMs has been created in the wake of emerging recognition motifs and the template-directed synthetic protocols they have forged. Among these motifs, those dependent on pp stacking in the form of donoracceptor interactions have played an important role in the increasingly rapid development of the field. The few integrated systems that have so far emerged based on this class of MIMs demonstrate their ability to act as active components in many potential applications. This review focuses on the progress which has been accomplished during the past decade involving MIMs comprising aromatic pp stacking interactions. While progress has been remarkable, opportunities still abound for MIMs assembled by pp recognition.