Ordered Graphane Nanoribbons Synthesized via High-Pressure Diels–Alder Polymerization of 2,2′-Bipyrazine

Abstract

Graphane shares the same two-dimensional honeycomb structure of graphene, but its saturated carbon skeleton gives rise to a bandgap and therefore provides more possibilities for the development of novel carbon-based semiconductors. However, the hydrogenation of graphene usually leads to disordered and incompletely hydrogenated graphane, and the precise synthesis of graphane with a specific configuration is still very challenging. Here, we synthesized a crystalline graphane nanoribbon (GANR) via pressure-induced polymerization of 2,2′-bipyrazine (BPZ). By performing Rietveld refinement of in situ neutron diffraction data, nuclear magnetic resonance spectroscopy, infrared spectra, and theoretical calculation, we found that BPZ experienced Diels–Alder polymerization between the π···π stacked aromatic rings and formed extended boat-GANR structures with exceptional long-range order. The unreacted −C═N– groups bridge the two ends of the boat and are ready for further functionalization. The GANR has a bandgap of 2.25 eV, with booming photoelectric response (I_ON/I_OFF = 18.8). Our work highlights that high-pressure topochemical polymerization is a promising method for the precise synthesis of graphane with specific structure and desired properties.