Tuning Aromaticity, Stability and Radicaloid Character of Periacenes by Chemical BN Doping

In this work, the stability, aromaticity and radical character of pristine and eleven BN-doped armchair 5 and zigzag 5, 6, and 7 periacenes, were chosen for studying the effect of different doping schemes to stabilize the periacene, and to direct the open-shell density into specific regions of the PAH sheets. Ab initio multireference methods and different DFT functionals were used to analyze the singlet triplet (ST) energy. Moreover, a range of descriptors were used to characterize the open-shell character and aromaticity of the different doped structures. The overall results provide a good overview of the efficiency of the different doping topologies. In general, because of the closed-shell character of the borazine doping units, the role of the doping is to reduce the strong open-shell character of the pristine periacenes. Substitutions along the zigzag edges has a significant effect while doping along the armchair edges is not significant.