Stability and Aromaticity in Chemically Modified (ma,nz ; m=5,7/n=5-7) Periacenes

1) the description of the PAHs electronic properties poses challenges because they exhibit an open-shell character in their ground state.
2) A possible alternative to decrease the high reactivity consists in modifying the structure by replacing carbon atoms/rings by other elements.
3) Most of the proposed modifications increase the S-T splitting and decreases the number of fractional occupancy , compared to the pristine periacenes.
4) The substitution of carbon rings by BN-rings generate more stable structures, in the visible range, which can be applyied as organic semicondoctors.