Self-assembly of sulfur-containing heterocyclic compounds constructed by thianthrene units and their sulfonium salts

The Properties, Synthesis, and Materials Applications of 1,4-Dithiins and Thianthrenes

1,4-Dithiin and its dibenzo-analogue, thianthrene, represent a class of non-aromatic, sulfur-rich heterocycles. Their unique properties, stemming from both their non-planar structures and reversible one- and two-electron oxidations, serve as primary motivators for their use in the development of new materials. The applications of 1,4-dithiins and thianthrenes are rich and diverse, having been used for energy storage and harvesting, and the synthesis of phosphorescent compounds and porous polymers, among other uses. This review offers first an overview of the properties of 1,4-dithiin and thianthrene. Next, we describe enabling synthetic methodology to access 1,4-dithiins and thianthrenes with various substitution patterns. Lastly, the utility of 1,4-dithiin and thianthrene in the construction and design of new materials is detailed using select literature examples.

1 Introduction

2 Properties of 1,4-Dithiins and Thianthrenes

3 Synthesis of 1,4-Dithiins and Thianthrenes

3.1 Synthesis of 1,4-Dithiins

3.2 Synthesis of Thianthrenes

4 Application of 1,4-Dithiins and Thianthrenes in Materials

4.1 Thianthrene-Containing Polymers

4.2 Thianthrene in Redox-Active Materials

4.3 Thianthrenes and 1,4-Dithiins in Supramolecular Chemistry and Self-Assembly

4.4 Thianthrenes in Phosphorescent Materials

4.5 Thianthrenes with Other Interesting Photophysical Properties

4.6 Thianthrenes in the Synthesis of Non-natural Products

5 Conclusion

A self-assembled M2L2 truncated square and its application as a container for fullerenes

An unprecedented bisthianthrene dipyridyl ligand was designed and synthesized for coordination driven self-assembly. The combination of this conformationally dynamic linker with a 90° convergent metal corner exclusively afforded a novel M₂L₂ truncated square-like metallamacrocycle. The single crystal X-ray structure reveals a belt-shaped geometry with a cavity diameter of ca. 13.7 Å. The breathable cavity and electron-rich thianthreno panels enable the highly efficient binding of the fullerenes C₆₀ (K_a = 5.1 × 10⁶ M^-1) and C₇₀ (K_a = 3.7 × 10⁶ M^-1). The encapsulation of C₆₀ is fully confirmed by NMR, mass spectroscopy and single crystal X-ray diffraction analyses. The cyclic voltammograms further reveal that the truncated square is redox active. The strong binding affinity, adaptive complexation, and redox activity of the thianthrene-incorporated metallamacrocycle provide new insights into the design of supramolecular hosts.