Post-functionalization of end-capped twistacenes with pyrene units

Abstract

The size, shape, and edge structure of nanographenes can significantly affect their physical properties. Meanwhile, the introduction of a pentagon, heptagon, or octagon into the parent nanographenes, along with various heterorings, might result in the formation of curved nanographenes possessing a Riemann surface and/or defects, which induces chirality, along with tailoring the optical, electronic and magnetic properties. In this review, we summarize progress in designing and synthesizing linear end-capped twistacenes and heterotwistacenes with pyrene units, non-hexagonal carbocycle-embedded curved nanographenes and chiral helicene-containing nanographenes based on the post-functionalization of twistacenes 9,14-diphenyldibenzo[de,qr]tetracene and 4,9,13,18-tetraphenyldibenzo[hi,uv]hexacene that can be prepared through a Diels–Alder reaction between substituted 2-aminobenzoic acids (aryne precursors) and dienenone/tetraenenone (diene). Moreover, systematic structure–property relationships between molecular structure, electronic dispersion, doping heteroatoms, self-assembly behavior and optoelectronic properties, including magnetic responses triggered by stimuli and chiroptical properties, will be illustrated in detail. In addition, we further unveil the significant role of the as-prepared materials in organic light-emitting diodes, photochemical switches, lasers, memristors, etc. Thereafter, we highlight our perspective on potential advances based on post-functionalization of twistacene to stimulate research interest, including two-dimensional chiral helicene-based nanographenes, three-dimensional nanotube fragments with well-defined molecular structures, and covalent organic frameworks bearing large π-conjugated building blocks with enhanced conductivity.