Revisiting the formation and tunable dissociation of a [2]pseudorotaxane formed by slippage approach

π-Stacking Stopper-Macrocycle Stabilized Dynamically Interlocked [2]Rotaxanes

The synthesis of mechanically interlocked molecules is valuable due to their unique topologies. With π-stacking intercomponent interaction, e.g., phenanthroline and anthracene, novel [2]rotaxanes have been synthesized by dynamic imine clipping reaction. Their X-ray crystal structures indicate the π-stackings between the anthracene moiety (stopper) on the thread and the (hetero)aromatic rings at the macrocycle of the rotaxanes. Moreover, the length of glycol chains affects the extra π-stacking intercomponent interactions between the phenyl groups and the dimethoxy phenyl groups on the thread. Dynamic combinatorial library has shown at best 84% distribution of anthracene-threaded phenanthroline-based rotaxane, coinciding with the crystallography in that the additional π-stacking intercomponent interactions could increase the thermodynamic stability and selectivity of the rotaxanes.

A Versatile Axle for the Construction of Disassemblage Rotaxanes

Rotaxanes are unique mechanical devices that hold great promise as sensors. We report on two new rotaxanes that contain an acid or base sensitive trigger and readily disassemble in a wide range of environments. Disassemblage was observed under TLC and ¹H-NMR analysis. The axle is highly charged, which enhances solubility in aqueous environments, and can be readily derivatized with sensor components. The trigger was swapped in a one-pot method, which is promising for the rapid production of a series of sensors.