Structure as a strategy

We live in a time when chemists can arrange atoms, molecules and layers with a precision that was once unimaginable. Progress in materials chemistry has often come from changing what things are made of, yet today we understand that how those components are arranged is just as important. Structure, and the interactions it enables, can be as powerful as composition in tuning materials’ properties and uncovering new phenomena and functions.

Here are three recent studies that come from fields that illustrate this notion. First up is a metal–organic framework (MOF) where each cobalt–methyl site binds two carbon monoxide molecules, delivering unusually high adsorption capacity at ambient conditions. MOFs are the epitome of how structure governs function: their porosity emerges from the way metal nodes and organic linkers assemble into networks rather than from the components alone.

Metal sites in MOFs can generally only accommodate a single guest molecule. The example we report is unusual because it can bind a second gas molecule after binding the first. This happens thanks to an arrangement that allows cobalt to undergo a spin-state transition and a related change in geometry, lowering the energy barrier for further coordination.

Next is a two-dimensional aromatic polyamide film whose gas impermeability rivals that of pristine graphene. Unlike conventional polymers, which combine ordered crystalline domains with amorphous ones that allow gas to pass through, these films stack their 2D layers in an offset pattern. This arrangement means pores in the sheet do not line up, creating a barrier reminiscent of a two-dimensional crystal, but one that’s much easier to process.

Finally, we have a story about magic-angle graphene. Twisting graphene layers by just over one degree with respect to each other transforms the material into a superconductor – but exactly how that simple structural change leads to a completely new property has been a mystery. Researchers have now figured out how the material’s electronic properties change, hinting at an ‘unconventional’ mode of superconduction.

These examples remind us that structural precision can transform familiar materials and building blocks into something fundamentally new. In the future, the most significant discoveries may come not from what we add, but from how we arrange what we already have.