Sulfur[n]arenes: Synthesis and Solid-State Supramolecular Dimerization via Multiple Sulfur···Sulfur Interactions

Controlling structural dimensionality is key to designing supramolecular assemblies with tunable properties. Herein, we report synthesis of a series of new macrocycles, termed ″sulfur[n]arenes″, containing multiple sulfur atoms. They show discrete self-assembly structures by cooperative σ-hole interactions between chemically identical sulfur atoms. Single-crystal X-ray diffraction analysis revealed that sulfur[5]arenes form discrete dimer structures stabilized by multiple S···S interactions. Computational studies suggested that inclusion of alkyl chains stabilizes unidirectional orientation of monomer units, maximizing these interactions. Additionally, macrocyclization significantly enhanced fluorescence quantum yield from corresponding monomer (up to Φ_FL = 0.88) by suppressing singlet-to-triplet intersystem crossing and nonradiative decay from the excited state.