Tetraphenylhexaazaanthracenes: 16π Weakly Antiaromatic Species with Singlet Ground States
Christos P Constantinides1, Georgia A Zissimou1, Andrey A Berezin1
1Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus.
Abstract:
Tetraphenylhexaazaanthracene, TPHA-1, is a fluorescent zwitterionic biscyanine with a closed-shell singlet ground state. TPHA-1 overcomes its weak 16π antiaromaticity by partitioning its π system into 6π positive and 10π negative cyanines. The synthesis of TPHA-1 is low yielding and accompanied by two analogous TPHA isomers: the deep red, non-charge-separated, quinoidal TPHA-2, and the deep green TPHA-3 that partitions into two equal but oppositely charged 8π cyanines. The three TPHA isomers are compared.
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