Using Slippage to Construct a Prototypical Molecular “Lock & Lock” Box

Abstract

We report a new slippage system based on p-tert-butylbenzyl-terminated imidazolium ions and di(ethylene glycol)containing macrocycles and their use as linking units for the construction of a prototypical molecular "Lock & Lock" box from a resorcinarene-based cavitand "bowl" and a porphyrin "cover". The multivalent structure with four slippage linkers provided the molecular box with high stability, yet the system dissociated into its two components upon application of suitable external stimuli.

Metastable doubly threaded [3]rotaxanes with a large macrocycle

“…Controlling environmental conditions such as temperature, pH, and solvent polarity combined with this unique feature of metastable rotaxanes has been utilized in controlled release applications. [43][44][45] Furthermore, metastable rotaxanes have been employed in the development of molecular pumps, [46][47][48][49] chemical protection, [50][51][52] modiable molecular containers, 53 and bacterial imaging probes. 54 All of the rotaxane materials discussed above are based on singly-threaded architectures.…”

Mechanically interlocked molecular handcuffs

“…A related (4)handcuff [2]rotaxane has been reported 94 that combines a resorcinarene-based cavitand with four crown ether macrocyclic appendages with a porphyrin decorated with four imidazolium arms. Similar in architecture to Tanaka's (4)handcuff [2]rotaxanes, the authors compared the cavitand to a “bowl” and the porphyrin component to the lid of that bowl.…”

Balancing ring and stopper group size to control the stability of doubly threaded [3]rotaxanes

“…20 Matching the correctly sized ring to stopper group is critical for achieving a stable interlocked molecule, 21,22 and prior studies have shown that depending on the relative size of stopper and macrocycle, the ring may undergo a slippage process where it dethreads from the dumbbell yielding the noninterlocked components. [23][24][25][26] Accessing different slippage rates in these metastable rotaxanes is possible and such interlocked compounds have been shown to be useful as a means of chemical protection, 27,28 constructing molecular pumps, [29][30][31] and the assembly of more complex architectures such as molecular containers 32 and supramolecular networks. 33 An important design parameter that has emerged in rotaxane synthesis and application is macrocycle size.…”