Robust dynamics.

Although metal-organic frameworks are extensive in number and have found widespread applications, there remains a need to add complexity to their structures in a controlled manner. It is inevitable that frameworks capable of dynamics will be required. However, as in other extended structures, when they are flexible, they fail. We propose that mechanically interlocked molecules be inserted covalently into the rigid framework backbone such that they are mounted as integrated components, capable of dynamics, without compromising the fidelity of the entire system. We have coined the term 'robust dynamics' to describe constructs where the repeated dynamics of one entity does not affect the integrity of any others linked to it. The implication of this concept for dynamic molecules, whose performance has the disadvantages of random motion, is to bring them to a standstill in three-dimensional extended structures and thus significantly enhance their order, and ultimately their coherence and performance.