Theoretical studies of one- and two-photon absorption properties for three molecules with different centers (B and N) and peripheral substituted groups [N(CH3)2 and CN]

Three molecules with different centers (boron and nitrogen) and peripheral substituted groups [N(CH3)2 and CN] have been theoretically studied with B3LYP/6-31G(d) associated with ZINDO and sum-over-states methods. The maximum two-photon absorption cross-section δmax of the molecule with boron (B) center and N(CH3)2 peripheral group is larger than that of the molecule with nitrogen (N) center and N(CH3)2 peripheral group. As for the two molecules with N center, the δmax is obviously increased with the change from N(CH3)2 to CN group. This indicates that the large intramolecular charge transfer is in favor of the TPA response.