2025/03/13 by Ziqiang Xu, Suriguga Meng, Zhiyu Zhang +5 · 1 voice
Chemistry · Engineering · #Synthesis and Properties of Aromatic Compounds #Fullerene Chemistry and Applications #Molecular Junctions and Nanostructures
paper · pdf · doi:10.1021/prechem.5c00001
High Resolution Image Download MS PowerPoint Slide Twisted nanographenes (NGs) are currently attracting a lot of attention owing to their geometrical and electronic structures that differ substantively from conventional planar and nonplanar NGs, while the strategic synthesis of twisted NGs is still a topic of interest because the products are often interconvertible among unidirectionally, alternatively, or randomly twisted geometries and otherwise obtained as a mixture of them. Herein, we report the conformationally specific synthesis of twisted NGs where the geometry was reinforced by introducing 1,4-dioxane rings at a K-region of a central pyrene core that bears a large contortion. The 1,4-dioxane rings were generated by semi-deprotection, of tetraoxa[4.4.4]propellanes in precursor molecules, which were confirmed to be engaged in forming C–C bonds via a Friedel–Crafts type mechanism. The large contortion within the pyrene core causes a narrowed HOMO–LUMO gap on account of unusual p z -lobe overlap between + z and − z sides, giving rise to red emission with a high quantum yield of 94% as well as stable redox processes of 2e – uptake/release.