Cumulenes are long chains of carbon atoms, linked by double bonds. The plane of each π-bond is perpendicular to the one before it. This pattern gives rise to helical orbitals running the length of the molecule.

Gemma Solomon and her research group at the University of Copenhagen has shown – through computer modelling – that these molecules conduct electricity, not linearly, but in a circular fashion. On this scale, quantum effects become significant, which affects how the electrons behave.

"Unlike the wires we know from everyday life, where electric current runs directly through the wire, the current runs in a circular fashion as it proceeds through these molecules. This behaviour is due to a quantum mechanical effect known as electrohelicity, which in this case causes electrons in molecules to move in a helical fashion, spiralling around the molecule."

Molecular electronics – the use of single molecules that conduct electricity – has potentially huge consequences for the electronics industry. As single molecules are so small, they could be used in tiny electrical components.

"Today, research in molecular electronics, in terms of using single molecules, is still at a conceptual stage", says Dr Solomon. "But organic electronics, using films of molecules, is an extremely important technology in many consumer products."

"In the medium term (next five years) we are trying to understand the basic rules for how electrons move through molecules. The circular currents we calculated suggest that these molecules might be candidates for spin-selective transport and/or sensitivity to magnetic fields, and both of these possibilities remain to be investigated. We hope that at some point these quantum effects can be used in electronic devices which are nothing like the ones we use today."

This article is free to read in our open access, flagship journal Chemical Science: Marc Garner, Gemma Solomon et al., Chem. Sci., 2019, Advance Article. DOI: 10.1039/C8SC05464A. You can access our 2019 ChemSci Picks in this article collection.