Mixed-Valence Superstructure Assembled from a Mixed-Valence Host-Guest Complex

Abstract

Herein, we report an unprecedented mixed-valence crystal superstructure that consists of a 2:1 host-guest complex [MV⊂(CBPQT)2]2/3+ [MV = methyl viologen, CBPQT = cyclobis(paraquat-p-phenylene)]. One electron is distributed statistically between three [MV⊂(CBPQT)2]•+ composed of a total of 15 viologen units. The mixed-valence state is validated by single-crystal X-ray crystallography, which supports an empirical formula of [MV⊂(CBPQT)2]3·(PF6)2 for the body-centered cubic superstructure. Electron paramagnetic resonance provides further evidence of electron delocalization. Quantum chemistry calculations confirm the mixed-valence state in the crystal superstructure. Our findings demonstrate that precise tuning of the redox states in host-guest systems can lead to a promising supramolecular strategy for achieving long-range electron delocalization in solid-state devices.