Synthesis and derivatization of an isomer of N-heterotriangulene bearing five-, six- and seven-membered rings around the central nitrogen atom

The functionalization of N-heterotriangulenes has been extensively investigated for their potentials as optoelectronic materials. However, study on the influence of molecular geometry on the property of N-heterotriangulene is still rare. Here we present the synthesis of an isomer of N-heterotriangulene containing five-, six- and seven-membered rings around the central nitrogen atom. The isomer can be further derivatized by condensing with orth-diamine compounds to extend the molecular conjugation. The photophysical and electrochemical properties of related compounds are characterized. The isomer bearing three carbonyl groups demonstrates room temperature phosporescence, which is absent in the corresponding carbonyl-bridged N-heterotriangulene. Furthermore, the chemical oxidation of one of the isomers of N-heterotriangulene to generate cationic radical is also studied.