Aromatic saddles containing two heptagons.
Soluble derivatives of C70H26 (1a,b) and C70H30 (2a,b), two new saddle-shaped polycyclic arenes containing two heptagons, were successfully synthesized from saddle-shaped diketones (3a,b), whose carbonyl groups are the key in the reactions to extend the polycyclic π-framework. As found from the crystal structures, the polycyclic backbone of 1b has a deep saddle shape, while that of 2b is even more distorted because of the existence of two [4]-helicene moieties. On the basis of crystal structures, local aromaticity and nonplanarity of individual rings in the saddle-shaped π-backbone were analyzed, and were found to follow Clar's rule in general. It was found that 1b and 3b behaved as p-type semiconductors in solution-processed thin film transistors while the amorphous films of 2b appeared insulating.
†Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Kwan Yin
KY
Cheung
†Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Xiaomin
X
Xu
†Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.|‡Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee), Hong Kong, China.
Qian
Q
Miao