▎ 摘　　要

In this work we study the intricacies of the electronic structure properties of triangular graphene nanofragments (TGNFs) in their ground and low-lying excited states by means of ab initio quantum chemistry calculations. We focus our attention on the radical and diradical characters of phenalenyl and triangulene, the smallest members of the TGNF family, and we describe the nature of their low-lying excited states. Moreover, we rationalize the modulation of the electronic and magnetic properties by means of selective boron or nitrogen substitution of carbon sites and by hydrogen saturation. The obtained results aim to guide future design of graphene-based materials with well-defined properties.