Synthesis of a biphenylene nanoribbon by compressing biphenylene under extreme conditions

Nonbenzenoid graphene nanoribbons such as biphenylene networks have gained increasing attention owing to their promising electronic and transport properties, but their scalable synthesis is still a huge challenge. Pressure-induced topochemical polymerization is an effective method to assemble molecular units into extended carbon materials, and the structure and properties of the carbon material can be tuned by modifying its molecular precursors. Herein, by directly compressing biphenylene at room temperature, we successfully synthesized crystalline biphenylene nanoribbons in milligram scale. By combining the spectroscopy and single crystal X-ray diffraction methods as well as theoretical calculation, we found that biphenylene experiences a minor phase transition above 3 GPa, and two phenyls in biphenylene undergo sequential para-polymerization along the a-axis to form a ribbon structure at 14 GPa. Our work provides an important reference for the high-pressure reaction of aromatics and the synthesis of complex nanoribbons.