Probing peripheral H-bonding functionalities in BN-doped polycyclic aromatic hydrocarbons.

The replacement of carbon atoms at the zigzag periphery of a benzo[fg]tetracenyl derivative with an NBN atomic triad allows the formation of heteroatom-doped polycyclic aromatic hydrocarbon (PAH) isosteres, which expose BN mimics of the amidic NH functions. Their ability to form H-bonded complexes has never been touched so far. Herein, we report the first solution recognition studies of peripherally NBN-doped PAHs to form H-bonded DD center dot AA- and ADDA center dot DAAD-type complexes with suitable complementary H-bonding acceptor partners. The first determination of K-a in solution showed that the 1:1 association strength is around 27 +/- 1 M-1 for the DD center dot AA complexes in C6D6, whereas it rises to 1820 +/- 130 M-1 for the ADDA center dot DAAD array in CDCl3. Given the interest of BN-doped polyaromatic hydrocarbons in supramolecular and materials chemistry, it is expected that these findings will open new possibilities to design novel materials, where the H-bonding properties of peripheral NH hydrogens could serve as anchors to tailor the organizational properties of PAHs.