Redox-active multi-thianthrene cycloparaphenylenes: synthesis and supramolecular properties

Thianthrene is a widely used building-block for developing p-type organic semiconductors. The rich electrochemistry of thianthrene enables a switch between its characteristic nonplanar and planar forms, and its incorporation into macrocyclic systems can provide increased solubility and improved host-guest complexation. Cycloparaphenylenes (CPPs) are a relatively new class of nonplanar aromatic macrocycles whose stepwise synthesis enables precise control over their properties. In this work, we report high-yielding transformations of fluorinated CPPs into multi-thianthrene-containing strained macrocyclic nanocarbons. Single crystal X-ray diffraction of dodeca-substituted CPP (2) reveals tub-shaped 5,7,12,14-tetrathiapentacene (TTP) units that curve around neighboring CPPs to form hexagonal crystals. Host-guest complexation with C₆₀ shows increased binding constants upon TTP inclusion, and cyclic voltammetry reveals that TTP incorporation lowers oxidation potentials of the CPPs compared to all-hydrocarbon counterparts. This efficient strategy for introducing functional heterocycles into CPPs expands the toolkit for designing strained, pi-rich, redox-active macrocycles with tunable supramolecular properties.