▎ 摘　　要

The effect of the substituents on the electronic properties of graphene nanoflakes possessing a high spin ground state, has been studied at D3bj dispersion corrected B3LYP/cc-pVDZ, and CAS/6-31G(d) levels of theory. The results of DFT and CAS calculations qualitatively agree with each other. The substituents affect the nature of the ground state. The electron withdrawing substituents, especially these with cyano groups favor the singlet ground state. The effect of the electron donating groups is more erratic. They can promote both high and low spin ground states. The side groups affect the topology of singly occupied molecular orbitals, modifying exchange interactions. Hence, depending on the type of substituents, one or another spin state could be favored. The calculations confirmed that the origin of the high spin ground state in these systems is attributed to the nondisjointed character of the occupied orbitals causing strong exchange coupling between the electrons. The substitution of the nanoflake increases the band gap and their reorganization energies.