Trichalcogenasumanenes were synthesized on a multigram scale through a two-step approach that takes advantage of non-pyrolytic cyclization and solventless ring contraction. Solid-state structure and photophysical investigations demonstrate that these compounds are promising candidates for electronic materials.

The transformation of trichalcogenasumanene buckybowls into donor-acceptor-type [5-6-7] fused polyheterocycles is disclosed. The strategy involves a highly efficient ring-opening of the flanking benzene upon oxidation at room temperature, and facile ring closure by functional-group transformation. Crystallographic studies indicate that the resulting [5-6-7] fused polyheterocycles possess a planar conformation owing to the release of ring strain by expansion of one of the six-membered flanking rings to the seven-membered one. Additionally, the [5-6-7] fused polyheterocycles bear electron-withdrawing groups, which reduce the HOMO-LUMO energy gap, and display broad absorption bands extending to λ=590 nm. Consequently, these compounds show strong red emission with fluorescence quantum yields of up to 38 %.

TTF derivatives decorated with four aryls through the sulfur bridges are employed to form the donoracceptor type inclusion complexes with fullerenes. The key factor for the formation of inclusion complexes is the introduction of structural flexibility in TTF molecules along with the molecular size matching with fullerenes. A crystallographic study indicates that the structures of the resulting complexes are stabilized by a multidimensional intermolecular interaction network consisting of TTF cores, peripheral aryls, and fullerenes, which in turn gives rise to the electronic communication between the donor and the acceptor as proved by the solid state absorption spectra. Moreover, the fullerene molecules form the two-dimensional sheet structure in the complexes.

A library of tetrathiafulvalene (TTF) derivatives (TTF-1-TTF-47) bearing aryl groups attached through sulfur bridges has been created. The peripheral aryl groups exert a significant influence on both the electronic and crystallographic properties of the resulting TTFs. These TTFs display broad absorption bands at 400-500 nm caused by intramolecular charge-transfer transitions between the aryl groups and central TTF core, and their first redox potentials increase with increasing electron-withdrawing ability of the aryl groups. In their crystal structures (22 examples), the central TTF cores adopt various conformations, including chair, half-chair, boat, and planar conformations. Moreover, the peripheral aryl groups exhibit multiple alignment modes with respect to the central TTF core, caused by their rotation about the two C-S bonds of the sulfur bridges. The packing motifs of these TTFs depend on both the nature of the aryl groups and their spatial alignment modes. Driven by intermolecular van der Waals forces and π-π interactions between the aryl groups and between the aryl groups and the TTF core, these TTFs adopt various packing structures. As a typical example, TTF-14, an achiral molecule, adopts a helical chain stack through intermolecular atomic close contacts. Moreover, the molecular geometries and packing motifs of these TTFs are sensitive to environmental variation, as exemplified by TTF-28, which adopts three distinct crystal modifications with diverse molecular geometries and stacking modes under different crystallization conditions. This work indicates that these TTFs are potential candidates as electronic materials, as well as functional building blocks for supramolecular assembly.

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