Welcome to CHI Group
Laboratory of pi-conjugated molecules and materials
Our Research Areas
The Chi Research Group focuses on the design, synthesis, and fundamental understanding of novel π-conjugated molecular systems with unconventional structures, electronic configurations, and unique optical, electronic, and magnetic properties. Our research lies at the interface of synthetic organic chemistry, physical organic chemistry, and molecular materials science, with particular emphasis on developing innovative synthetic strategies to access structurally challenging carbon-based and heteroatom-containing π-conjugated architectures.
A central theme of our research is to understand how molecular structure, topology, curvature, aromaticity, and π-electron delocalization govern the electronic structures and physical properties of conjugated molecules. By combining precision molecular synthesis with advanced experimental characterization and theoretical investigations, we aim to uncover new molecular phenomena, establish fundamental structure–property relationships, and develop functional molecular materials with potential applications in organic electronics, molecular spintronics, and quantum technologies.
Over the past two decades, our group has made significant contributions to the synthesis and investigation of fully π-conjugated carbon nanobelts, nonalternant polycyclic hydrocarbons, extended acenes and nanographenes, open-shell molecular systems, and π-conjugated macrocycles and cages. These studies have addressed longstanding synthetic challenges and revealed unconventional electronic structures, including open-shell singlet ground states, tunable diradical character, and global aromaticity and antiaromaticity. Our research is organized into six closely connected directions.
π-Conjugated Carbon Nanobelts
In 2021, our group reported the synthesis of octabenzo[12]cyclacene, a fully π-conjugated zigzag-edged carbon nanobelt (CNB), addressing a longstanding synthetic challenge. In 2025, we further developed pentagon-embedded nonalternant CNBs exhibiting enhanced π-electron delocalization, narrow energy gaps, and unusual open-shell electronic structures and global aromaticity. Building on these advances, we aim to develop new synthetic strategies for carbon nanobelts with diverse sizes, topologies, and electronic structures, and to investigate their aromaticity, spin properties, and potential applications in molecular electronics, spintronics, and quantum technologies.
π-Extended Nonalternant Hydrocarbons
Nonalternant hydrocarbons are an important class of π-conjugated carbon frameworks containing odd-membered rings, such as five- and seven-membered carbocycles. Unlike conventional benzenoid aromatic hydrocarbons, these molecules can exhibit unconventional molecular orbital characteristics, unusual aromaticity and antiaromaticity, narrow electronic energy gaps, and distinctive optical, redox, and magnetic properties. Our group has developed synthetic strategies to access a variety of structurally challenging π-extended nonalternant hydrocarbons, including core-expanded indacenes, fused indacene dimers, azulene-fused acenes, azulene-fused indacenes, and bis(azuleno)pentalenes. These molecular architectures provide unique platforms for investigating how ring topology, fusion patterns, and interactions between aromatic and antiaromatic subunits influence electronic structures and molecular properties. Through these studies, we aim to establish new molecular design principles for controlling aromaticity, electronic structure, open-shell character, and charge transport in unconventional carbon frameworks.
Extended Acenes, Nanographenes, and Open-Shell π-Conjugated Systems
Extended acenes and nanographenes are important molecular platforms for understanding the relationship between π-electron conjugation, molecular geometry, electronic structure, and magnetic properties. Their narrow energy gaps, extended π-electron delocalization, and potential open-shell ground states make them attractive candidates for organic electronics, molecular spintronics, and emerging quantum technologies. However, their high chemical reactivity and limited stability present major challenges for molecular synthesis and characterization. Our group has developed a range of molecular design and stabilization strategies for synthesizing extended acenes, heteroacenes, quinoidal acene analogues, peri-acenes, and circumacenes. These studies contribute to the fundamental understanding of organic diradicals, aromaticity, and molecular magnetism, while providing molecular building blocks for future spin-based and quantum functional materials.
Dynamic Covalent Chemistry and Stimuli-Responsive Radical Materials
Dynamic covalent chemistry provides a powerful strategy for constructing complex molecular architectures through reversible bond formation and cleavage. Our group is particularly interested in exploiting reversible carbon-carbon bond formation involving organic radicals to develop structurally complex molecular systems and stimuli-responsive functional materials. We have developed carbon-centered radical systems capable of undergoing reversible radical association and dissociation in response to external stimuli, including temperature, pressure, and solvent polarity. These studies provide new molecular design strategies for developing mechanochromic, thermochromic, and other stimuli-responsive organic materials.
Macrocycles and Molecular Cages: Global Aromaticity and Antiaromaticity
Our group develops innovative synthetic strategies based on dynamic covalent chemistry to construct structurally complex π-conjugated macrocycles, figure-eight molecules, and molecular cages. These architectures provide unique platforms for investigating how molecular topology, conformation, and electronic structure influence π-electron delocalization and aromaticity. We have demonstrated that quinoidal macrocycles exhibit unusual global aromaticity and antiaromaticity, which can be reversibly modulated through changes in oxidation state. Building on these discoveries, we aim to develop novel two- and three-dimensional π-conjugated architectures with diverse topologies and controllable electronic structures, and to explore their fundamental aromaticity, optical properties, and potential applications in molecular electronics and quantum materials.
Organic Electronic/Optoelectronic Materials
Conjugated materials are the cornerstone of organic electronics, revolutionizing the field with their unique electronic properties. These materials possess extended π-electron systems, allowing for efficient delocalization of charge carriers across their molecular structure. This intrinsic feature enables the creation of flexible, lightweight, and cost-effective electronic devices, such as organic solar cells, organic light-emitting diodes (OLEDs), and organic field-effect transistors (OFETs). The versatility of conjugated materials allows for tailored design and synthesis, paving the way for tunable optoelectronic properties to suit specific applications.
Our long-term research vision is to push the boundaries of synthetic π-conjugated chemistry by creating molecular architectures that are not only structurally unprecedented but also exhibit fundamentally new electronic and magnetic phenomena.
We aim to establish precise molecular control over topology, curvature, aromaticity, π-electron delocalization, and spin states, and to understand how these structural and electronic factors can be combined to generate novel molecular functionalities.
Through the integration of innovative synthetic chemistry, advanced physical characterization, and theoretical studies, we seek to bridge fundamental molecular discoveries with emerging opportunities in organic electronics, molecular spintronics, and quantum technologies.