# Organic Cage Rotaxanes

## TL;DR

This paper describes a new method to modify organic cages by attaching rotaxane units, which changes their physical and chemical properties.

## Contribution

A novel approach to functionalize organic cages using rotaxane units via a mechanical bond to modulate their properties.

## Key findings

- The mechanical bond was used to alter gas uptake, solubility, and thermal properties of organic cages.
- Cages with a defined number of interlocked components were synthesized using a scrambling methodology.
- Post-synthetic modification allowed controlled installation of rotaxane units on cage surfaces.

## Abstract

Organic cages are a robust class of molecular hosts with a myriad of applications in materials science. Despite this, there has been a paucity of explorations into the modification of their properties via external functionalization. In this work, [n]rotaxanes featuring unoccupied organic cages as stopper components and a small 2,2′‐bipyridine macrocycle were constructed using the active metal template (AMT) approach. By exploiting a scrambling methodology, it was possible to synthesize cages with a defined number of interlocked components (n = 2–4). The gas uptake, solubility, and thermal properties of the interlocked systems were compared against those of their constituent, non‐interlocked components. In this manner, we were able to demonstrate the potential of exploiting the mechanical bond for modulating the physiochemical properties of these molecular materials.

The synthesis of robust, amine‐based organic cages with a controllable number of alkyne functional groups is described. Subsequent post‐synthetic modification enabled installation of a defined number of rotaxane units on the external surfaces, resulting in changes to the physiochemical properties of the cages.