The flowering of Mechanically Interlocked Molecules: Novel approaches to the synthesis of rotaxanes and catenanes

Metastable doubly threaded [3]rotaxanes with a large macrocycle

“…8–15 The simplest and most-investigated version of a rotaxane is the singly threaded [2]rotaxane comprised of one macrocycle component kinetically trapped between the large stopper groups of the dumbbell-like component. 16,17 However, as the field continues to grow, there is increasing interest in looking towards higher order rotaxanes 6,18 (containing more rings, more dumbbells, or both) and their corresponding mechanically interlocked polymers (MIPs). 19,20 This has led to complex architectures capable of advanced function such as molecular elevators, 21,22 artificial molecular muscles, 23,24 molecular pulleys, 25 and more.…”

The Role of Dethreading Process in Pseudorotaxanes and Rotaxanes towards Advanced Applications: Recent Examples

“…In this scenario, the research group of Leigh was pioneer in the preparation of such a macrocycle by a dethreading of a benzylic amide rotaxane induced by a transesterification reaction of the stoppers of the thread. [46] More recently, Berna and coworkers reported the preparation of tetralactam macrocycles through the thermally and photochemically induced dethreading of fumaramidebased pseudo [2]rotaxanes. [29,30] The advantage of these methodologies which operate via the formation of rotaxanes lies in the increase in yield and the facilitation of the purification step.…”

“…Mechanically interlocked molecules (MIMs) are a type of compounds constituted by components which are bonded together through noncovalent interactions, forming a mechanical bond. [1][2][3] Within the range of intertwined compounds, rotaxanes are postulated as ideal candidates for the design of molecular machines, developing applications in a wide range of fields, [4][5][6] such as catalysis, [7][8][9][10][11][12][13][14] materials science [15][16][17][18][19][20][21][22][23][24] or medicinal chemistry. [25][26][27] Usually, the design of these structures seeks the stability of the mechanical bond, thus preventing the dissociation of the different components in order to carry out a specific function.…”

Preprogrammed assembly of supramolecular polymer networks via the controlled disassembly of a metastable rotaxane

“…Since the introduction of molecular meccano 1 , 2 a myriad of mechanically interlocked molecules (MIMs) has been reported 3 , from rotaxanes 4 – 6 and catenanes 7 – 9 to other fascinating superstructures 10 – 14 . The assembly of MIMs has been of particular interest in recent years 15 (new syntheses 16 and emerging host and guest elements 17 ), which is in stark contrast to the few studies that have explored their disassembly. These examples include the delivery of small molecules to a medium 18 – 21 and the degradation of crosslinked polymers using metastable rotaxanes 22 – 24 .…”