Synthesis of a Zwitterionic Open-Shell Bilayer Nanographene

• Published in: Meeting abstracts (Electrochemical Society) Vol. MA2025-01; no. 14; p. 1080
• Main Authors: Lión-Villar, Juan, Fernández-García, Jesús Manuel, Martín, Nazario
• Format: Journal Article
• Language: English
• Published: The Electrochemical Society, Inc 11.07.2025
• ISSN: 2151-2043; 2151-2035
• DOI: 10.1149/MA2025-01141080mtgabs

In recent years, molecular nanographenes (NGs) have emerged as a prominent scientific subject. Specifically, bilayer/multilayer NGs 1 are gaining relevance due to their potential as molecular models for investigating the fundamental physics that operate in systems like twisted bilayer graphene, 2 for instance. Bottom-up NGs synthesis serves here as a powerful tool for creating materials with atomistic precision and tuned optoelectronics, opening their applications in cutting-edge technologies like photovoltaics, spintronics or energy storage. 3 Two molecular nanographenes are reported in this work, both linking hexa- peri -hexabenzocoronenes (HBCs) fragments through a spirobi[fluorene] core. NG1 is decorated with ten tBu solubilizing groups in its periphery and is presented as a distorted co-facial bilayer in the crystal structure, while NG2 presents one of the HBCs substituted with five fluorine atoms (Figure 1), leading to an electron transfer process tanking place due to the structural bilayer formation. As a result, NG2 is a stable zwitterionic paramagnetic species bearing a radical cation and a radical anion located in the electron donor and electron acceptor HBCs, respectively. Theoretical calculations, magnetic and spectroelectrochemical measurements support the remarkable charge-separated ground state of NG2 . Furthermore, photoconductivity (DC) measurements show a significant increase of the charge carrier mobility in the case of NG2 (Σµ = 6 cm 2 V -1 s -1 ) compared to NG1 . The unprecedented character of this molecule spotlights the interest in further investigating the fundamental physics behind novel electron donor-acceptor graphene-like systems and explore their plausible applications in the semiconductor industry. Acknowledgments: collaboration with Juan Casado, Josefina Perles, Shu Seki and Jishan Wu. [1] P. Izquierdo-García et al., J. Am. Chem. Soc. 2023 , 145 , 11599. [2] Y. Cao et al. , Nature 2018 , 556 , 43. [3] Y. Zhang et al. , J. Am. Chem. Soc. 2021 , 143 , 5231. Figure 1