Redox-Active Multi-Thianthrene Cycloparaphenylenes: Synthesis and Supramolecular Properties

Thianthrene is a well-studied heterocyclic p-type organic semiconductor. 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 cycloparaphenylenes (CPPs) into multi-thianthrene-containing strained macrocyclic nanocarbons. Single crystal X-ray diffraction of our 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, with 2 strongly binding C60, and cyclic voltammetry reveals that TTP incorporation lowers oxidations potentials relative to all-hydrocarbon CPPs. This efficient strategy for introducing functional heterocycles into CPPs expands the toolkit for designing strained, pi-rich, redox-active macrocycles with tunable supramolecular properties.