Controllable synthesis of 6H-1,4-diazepine-2,3-dicarbonitrile nanocrystals and their optical properties

Organic nanostructures of 6H-1,4-Diazepine-2,3-dicarbonitrile (HDD) ranging from nanoparticles to nanoribbons have been controllably prepared. Changes in morphologies are observed to be accompanied with changes in optical properties. The HDD nanoparticles show a main emission at ca. 710 nm with a very weak shoulder at 625 nm, as nanoparticles gradually grow into nanoribbons, the predominant emission shifts to be centered at 625 nm at the expense of that at 710 nm. Shifts in the emission are proposed to come from different charge distributions of highest occupied molecular orbits (HOMO) induced by changing of intermolecular interactions, which is also evidenced by the quantum mechanics calculations.