화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.141, No.18, 7266-7270, 2019
Dicyclopenta[4,3,2,1-ghi:4 ',3 ',2 ',1 '-pqr]perylene: A Bowl-Shaped Fragment of Fullerene C-70 with Global Antiaromaticity
Solution-phase synthesis of buckybowls remains a big challenge, and there are limited reports on the fragments of C-70. Herein, we report a new basic subunit of C-70 with C-2v, symmetry, the dicyclopenta-[4,3,2,1-ghi:4',3',2',1'-pqr]perylene (2CP-Per). Its aryl substituted derivative 2CP-Per-Ar was synthesized and shows a bowl-shaped geometry according to X-ray crystallographic analysis. A fast bowl-to-bowl inversion process was observed above 183 K by variable temperature nuclear magnetic resonance (NMR), with a small inversion energy barrier. 2CP-Per-Ar displays amphoteric redox behavior with a small electrochemical energy gap (1.29 eV). Different from many other aromatic buckybowls, 2CP-Per exhibits global antiaromaticity with a strong paratropic ring current associated with the 16 pi-electrons rim, as revealed by NMR measurements and theoretic calculations. Its dianion is aromatic, similar to its isoelectronic structure coronene. Its dication is predicted to be aromatic, with a [6]annulene-within-[14]annulene structure.