Cutting and Rebuilding Molecules From the Inside to Create New Chiral Nanocarbons

Nanocarbons are molecular-scale carbon structures considered to be the building blocks for next-generation materials. Until now, scientists have built them by fusing small, flat carbon molecules together at their edges. Modifying the inside of a molecule was considered challenging because inner bonds are locked into flat, rigid structures that resist change. 

Researchers at Nagoya University in Japan have shown that a chemical process focused on the interior of a molecular structure can create chiral nanocarbons. Like our hands, these molecules exist in mirror-image left- and right-handed forms. The method, known as skeletal editing, allowed the research team to cut and reform bonds inside common flat carbon molecules, such as small pieces of graphene. They could then build new chiral nanocarbons in various shapes, including molecules with 10-carbon rings and a double helix.  

These new molecules do surprising things. They all glow with light that spirals as it travels. Two can hold multiple electrical charges without breaking. One of them also keeps its handed shape even at 280 degrees Celsius. Another assembles into a porous crystal that can trap and release carbon dioxide, a property that could be useful for gas storage materials. 

Skeletal editing has mainly been used by chemists to manufacture pharmaceuticals. This is the first time it has been applied to nanocarbon synthesis. The approach solved two persistent challenges. First, the researchers built a 10-carbon ring into large chiral nanocarbons, a combination not achieved before. Second, they showed that both left- and right-handed forms of complex nanocarbons can be produced (asymmetric synthesis), a feat only accomplished twice before with nanocarbons of this size. The findings were published in Nature Communications. 

“If you alter the inside of a molecule, it causes significant strain, so most reactions proceed around the molecule instead. Over time, this led to the assumption that the interior could not be modified,” said senior author Norihito Fukui, Associate Professor at the Graduate School of Engineering, Nagoya University. “However, with the right method and the right starting molecule, we can change the inside and create molecular shapes and structures that could not be made before.”  

Most nanocarbons are built from flat structures consisting of six-sidedrings, like small pieces cut from graphene. Carbon atoms naturally prefer to form these shapes because of the angles their bonds make. Chemists have recently found ways to include seven- and eight-sided rings. However, ten-sided rings and non-flat arrangements of six-sided rings have remained very difficult to build.

The double-helix molecule is made by cutting and reforming a bond. It self-assembles into crystals with spiral-shaped pores that trap and release carbon dioxide. This chiral porous material is the first of its kind. It is a cousin of the metal-organic frameworks (MOFs) that won the 2025 Nobel Prize in Chemistry.

The unique properties of these chiral molecules are what scientists look for when they design advanced materials for gas storage, ultra-low-power electronics, and next-generation encryption.

The findings extend skeletal editing beyond its traditional territory in pharmaceuticals. “We hope the approach will inspire other researchers to investigate what else can be built by editing the interior of molecules,” Fukui said.