LAUSR

Fullerene fragments, referred to as buckybowls, are garnering interest due to their distinctive molecular shapes and optoelectronic properties. Here we report the synthesis and characterization of a novel C70 subunit, diindeno[4,3,2,1-fghi:4',3',2',1'-opqr]perylene, that is substituted with either triethylsilyl(TES)-ethynyl or 2,4,6-triisopropylphenyl groups at the meta-positions. The resulting compounds (1 and 2) display a bowl-to-bowl inversion at room temperature. Notably, the substituent groups on the meta-positions alter both the geometric and electronic properties as well as crystal packing of the buckybowls. In contrast to the 2,4,6-triisopropylphenyl groups in 2, the TES-ethynyl groups in 1 lead to enhanced bond length alternation, resulting in weaker aromaticity of the six-membered rings of the buckybowl skeleton. 1 forms one-dimensional (1D) concave-in-convex stacking columns, and when 1 is blended with C70, the buckybowls encapsulate C70, and result in two-dimensional co-crystals. Organic field-effect transistor (OFET) measurements demonstrate that 1 displays a hole mobility of 0.31 cm2V-1s-1 and the 1-C70 co-crystal exhibits ambipolar transport characteristics with electron and hole mobilities approaching 0.40 and 0.07 cm2V-1s-1, respectively. This work demonstrates the potential of buckybowls for the development of organic semiconductors.