N/Si -Doped Nonbenzenoid Buckybowls with Tunable Configurations and Optoelectronic Properties

Incorporation of heteroatoms and nonbenzenoid rings into buckybowls, which feature intriguing bowl-shaped π-conjugated structures and exhibit unique properties, can tune their configurations and HOMO/LUMO energy levels, thereby modulating their physical properties. Herein, we report a class of π-extended buckybowls with a corannulene skeleton, bearing N/Si -doped 5/7 ring or 5/5/7/5 ring systems. Crystal structures of these new buckybowls reveal that their configurations are bowl, quasi-bowl, and nearly planar, respectively, indicating that these geometries can be tuned by varying the incorporated heteroatoms and nonbenzenoid ring fusion modes. Consequently, their intermolecular interactions and arrangements, assembly behaviors, and optoelectronic properties are adjustable. Among them, the buckybowl with an N/N -doped 5/5/7/5 ring system exhibits multiple functions, including narrow-band green fluorescence with a full width at half-maximum (fwhm) of 23 nm, long-lived phosphorescence with an afterglow duration of up to 30 s at 77 K, a unique complexation structure with C 60 showing noncovalent C 60 nanoribbons that are rarely reported, and a hole mobility of 0.194 cm 2 V –1 s –1 in organic field-effect transistor devices (OFETs). This implies that this buckybowl is a useful conjugated framework for creating multifunctional materials. Furthermore, the Si -doped buckybowl achieved a hole mobility of 0.9 cm 2 V –1 s –1, which is one of the highest values among buckybowls reported so far, and the resulting devices exhibited good photoelectric response in the near-ultraviolet region (405 nm).