Alternately Twisted, Electron-Rich Rylenes and Their Stable Cations

Solution-phase synthesis of long rylenes remains challenging due to their strong tendency to aggregate. Introducing backbone twist can reduce aggregation and simultaneously generate potential helical chirality. Herein, we report a series of rylene molecules–up to octarylene—bearing both odd- and even-numbered naphthalene units and multiple n-butoxy substituents at the bay/ortho positions, synthesized via stepwise cross-coupling followed by controlled oxidative dehydrogenation. Peri-attached 4-(trifluoromethyl)phenyl groups further stabilize the extended scaffolds. The electron-rich n-butoxy groups not only induce pronounced backbone twisting but also impart strong electron-donating character. X-ray crystallography reveals that long rylenes with two or more bay- tetra(n-butoxy) motifs adopt alternating P/M helicity rather than a homochiral helical conformation. These molecules exhibit clear length-dependent optical and electrochemical properties, with absorption and emission spanning the visible to near-infrared region. Their electron-rich nature enables facile formation of stable radical cations and dications. Solid-state structures of representative radical cations show distinct intermolecular stabilizing interactions, while ¹H NMR and ACID analyses of the dications reveal a systematic evolution from local to global aromaticity.