Periacenes, a class of polycyclic aromatic hydrocarbons (PAHs), have garnered significant recent interest, both as one of the few remaining synthetic challenges within the well-explored field of PAHs and due to their unusual predicted electronic structure. Theoretical calculations suggest that periacenes of sufficient size would display an antiferromagnetic ground state with strong spin localization along opposing zig-zag edges, making them of interest both scientifically and for various electronic and spintronic applications. However, extended periacenes have not previously been obtained through rational synthesis. Here we present a modular, scalable synthetic approach to bisacene structures, notably including 6,6’-bipentacene. Access to these structures facilitated a new approach to periacenes, in particular the longstanding synthetic target peripentacene, which we have synthesized by thermal cyclodehydrogenation on Au(111) and characterized by both scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM). We further demonstrate the extension of this synthetic approach to other bisacenes, including asymmetric examples and their corresponding periacenes, and discuss progress in the use of this approach to synthesize stabilized periacenes by solution-phase techniques. This new synthetic strategy promises to afford access to a structurally diverse class of periacenes and related PAHs as advanced materials for electronic, optical, and magnetic devices.

Extended periacenes: Synthesis from novel bisacenes and characterization by scanning probe microscopy

251st National Meeting (2016)

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