Organic Supramolecular Lattice Built from Triptycene Shows Topological Edge States

Researchers in Japan and Germany have directly observed topological edge states—electronic states that exist only at the edges of a structure and behave quite differently from those in its interior—in an assembly of organic molecules. The finding, published in the journal Nano Letters on September 2, 2026, demonstrates that supramolecular chemistry, the practice of designing materials by assembling molecules into larger architectures, can produce a hallmark of quantum material behavior that until now has been sought mainly in carefully engineered inorganic crystals. The work was carried out by a joint team from the National Institute for Materials Science (NIMS), Toyota Kosen (National Institute of Technology, Toyota College), Saga University, Nara Women’s University, Kiel University in Germany, and other institutions, led by Takashi Uchihashi, Deputy Director of NIMS’s Research Center for Materials Nanoarchitectonics.

The material at the heart of the study is a two-dimensional supramolecular lattice built from derivatives of triptycene, an organic molecule whose three flat planes are arranged around a central axis in a three-dimensional, propeller-like configuration. When the researchers assembled these triptycene derivatives, the molecules organized into a two-dimensional network that exhibits the properties of both of two celebrated lattice structures in condensed matter physics: the honeycomb lattice and the Kagome lattice. The resulting architecture is known as a diatomic Kagome lattice, a hybrid in which the two lattice types are effectively merged into a single periodic structure.

Each parent lattice carries its own scientific pedigree. The honeycomb lattice, named for its resemblance to bees’ honeycomb, is the arrangement of carbon atoms in graphene, a single layer of graphite. The Kagome lattice takes its name from a traditional Japanese Kagome craft basket pattern. Due to their unique electronic states, these lattices have been studied actively in recent years. However, according to the research team, hardly any studies have created a diatomic Kagome lattice, which can be described as a hybrid of these two lattices, in an actual material, making the present synthesis a notable addition to the small family of real systems with this geometry.

The obstacle that has kept organic molecules out of much of this arena is fundamental to their chemistry. Supramolecular structures are held together by relatively weak interactions between molecular units, and these interactions generally provide only weak electronic coupling between the constituent units, which has made supramolecules unsuitable for use as quantum materials. Quantum materials, by contrast, depend on strong electronic communication between their building blocks, which is why inorganic materials had mainly been used to synthesize topological materials. Inorganic compounds, however, impose significant issues regarding flexibility in design and synthesis, and this has motivated a call for the development of new design methods for quantum materials based on organic molecules.

The triptycene derivative addressed this problem through its three-dimensional geometry. Because the three planes constituting each triptycene derivative are arranged in a propeller-like configuration, adjacent planes of neighboring molecules come into direct physical contact with one another. These contacts create strong bonding between the molecules, a coupling denoted t1 in the team’s structural model, and it is this coupling that allows the assembled supramolecular structure to support the unique electronic states observed in the study. The fact that the team was able to design and synthesize this unique molecular structure, and then to assemble the molecules into a supramolecular structure, was the key to achieving the research result.

To determine whether the assembled structure actually behaved as a topological material, the team examined the prepared sample with a scanning tunneling microscope, an instrument capable of imaging surfaces and their electronic structure at the nanoscale. The measurements revealed a unique electronic state that exists only in the boundary, or edge, region between the two-dimensional structure of the organic molecules and its exterior—a state present at the edges but distinct from the electronic states in the interior of the lattice. Edge-localized states of this kind are what topological materials are known for, and their appearance in a molecular assembly was an immediate sign that the sample warranted closer theoretical scrutiny.

Detailed theoretical analysis confirmed this interpretation. The calculations showed that the observed edge state is a topological edge state derived from the mathematical structure of the system, technically called topology. This, the team reports, clearly demonstrates the properties of the sample as a quantum material. The study was conducted as an experimental investigation supported by theoretical analysis, and the reported observations are specific to this triptycene-derived diatomic Kagome lattice as examined by scanning tunneling microscopy and interpreted through the accompanying theory. The team also produced scanning tunneling microscope images showing both the shape of the fabricated supramolecular structure and the topological edge states present at its edge, providing a direct visual record of the phenomenon.

The broader significance lies in what the result opens up for materials design. Organic molecules offer a degree of structural design freedom that inorganic crystals do not: chemists can tune molecular structure and assembly behavior with considerable flexibility, potentially allowing quantum material properties to be designed into the molecular blueprint itself. By showing that a supramolecular structure can host topological electronic states, the team has established a new quantum material design approach using organic molecules, a domain in which quantum materials had previously been dominated by inorganic synthesis.

The researchers outline a set of possibilities for future development. By exploiting such unique lattice structures, they suggest it may become possible to switch between a high-mobility semiconductor-like state and a superconducting state, to achieve ultra-high-speed and ultra-low-power optical switching, and even to enable lossless energy transport at room temperature. These are goals for future materials development built on the current result rather than demonstrated capabilities of the present sample, and realizing them will require further work on materials design. The team states that it will now accelerate the development of materials for the application of quantum technology and work to realize a variety of quantum materials by making use of the flexible design that organic molecules enable.

The research was conducted by a team led by Takashi Uchihashi, Ryuichi Arafune, and Katsunori Wakabayashi of NIMS’s Research Center for Materials Nanoarchitectonics, together with Kunio Awaga of Toyota Kosen, Rie Suizu of Saga University, Masahisa Tsuchiizu of Nara Women’s University, and Richard Berndt of Kiel University in Germany. It was supported by JSPS Grants-in-Aid for Scientific Research under grant numbers 25H00867, 25K01670, 20H05621, 20H02707, 23K03322, 25K01609, and 22H05473, by the Strategic Basic Research Program PRESTO under grant number JPMJPR21A9, and by the World Premier International Research Center Initiative of Japan’s Ministry of Education, Culture, Sports, Science and Technology. The study, titled “Direct Observation of the Zigzag Edge States of a Supramolecular Diatomic Kagome Lattice,” was published online in Nano Letters, issued by the American Chemical Society, on September 2, 2026, under DOI 10.1021/acs.nanolett.6c03195.

Subject of Research: Direct observation of topological edge states in a supramolecular diatomic Kagome lattice built from triptycene-derived organic molecules

Article Title: Building quantum materials using supramolecular technology

Article References: Building quantum materials using supramolecular technology. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: topological edge states, supramolecular chemistry, triptycene, Kagome lattice, honeycomb lattice, quantum materials, organic molecules, scanning tunneling microscopy, Nano Letters, NIMS, two-dimensional materials, electronic coupling