Interlocked molecules articles from across Nature Portfolio

Knots reduce the tensile strength of macroscopic threads and fibres. Now it has been shown that the presence of a well-defined overhand knot in a polymer chain can substantially increase the rate of scission of the polymer under tension, as deformation of the polymer backbone induced by the tightening knot activates otherwise unreactive covalent bonds.

A rotaxane-based mechanochemical system enables force-controlled release of multiple cargo molecules that are appended to its molecular axle.

By virtue of the rotational motions of interlocked macrocycles, the authors describe a chameleon-like catenane host that can adjust its co-conformation for selective binding to copper(I) or sulfate ion. While the cationic copper(I) complex is achiral, the interlocked rings in the catenane host rotate and re-orient into a chiral co-conformation upon forming the anionic sulfate complex.

Mechanically interlocked structures in polymer backbones can give interesting functionality, but can be challenging to prepare and control. Here, the authors report the development of polymers with a daisy chain unit in the backbone that are capable of shape memory behaviour.

The study of cross-catenated metallacages could provide facile insights into achieving more precise control over low-symmetry/high-complexity hierarchical assembly systems but is currently lacking. Here, the authors report a cross-catenane formed between two position-isomeric Pt(II) metallacages in the solid state.

The synthesis of molecular knots remains challenging. Here, the authors report the synthesis of a chiral molecular trefoil metallaknot by self-assembly which contains only 54 atoms in the backbone.

A metal templating approach can be used to generate homo- and heterointerlocked cage structures.

Molecular knots and links retrofitted with iminopyrrole units make these assemblies intrinsically flexible, strengthening their potential application in molecular machinery.

Interlocking unstable motifs is a useful way to enhance their stability through shielding protection. Now, stable interlocked polyynes bearing several macrocycles have been prepared, including a [5]rotaxane having 34 contiguous alkynes with properties similar to those of carbyne.

Conformational dynamics are integral to enzyme catalysis, yet they are barely explored when designing synthetic catalysts. Now, a catenane-based organocatalyst, which dynamically switches between two conformations, speeds up the catalysis of carbodiimide hydration through spontaneous conformational adaptation for different reaction steps.

Interlocking macrocyclic carbon nanomaterials is an exciting way to tune their molecular properties, but all-conjugated catenanes and rotaxanes are extremely challenging to make. Now, fully π-conjugated [2]- and [3]catenanes as well as a [3]rotaxane have been prepared through an ‘active metal template’ approach.

From the realization of their true nature one hundred years ago to the latest approaches for structuring materials using molecular weaving, high-molecular-weight polymers still have much to offer society.