A complementary disk-shaped π electron donor–acceptor pair with high binding affinity

Hexaazatriphenylene triimides (HAT) have been shown to be a novel class of disk-shaped π electron acceptors that pair with donors with complementary shape and electron demands, such as triphenylene (TP) derivatives. The donor–acceptor (DA) pair forms a strong charge-transfer complex in CH2Cl2 with an association constant of 2.6 × 104 M−1, which is remarkable for a recognition system that is solely based on electrostatic interactions between two π systems. NMR studies, along with molecular modelling, have revealed a complementary charge distribution and an “eclipsed” conformation in the DA complex. The strong DA interaction results in extended alternating DA stacks in the thin film and mesophases.