Theoretical study of two-photon absorption properties for donor/acceptor-functionalized tetrakis(phenylethynyl)benzenes and bis(dehydrobenzoannuleno)benzenes

On the basis of the equilibrium geometric structures obtained at the B3LYP/6-31G level, the one-photon absorption (OPA) and two-photon absorption (TPA) properties of donor/acceptor-functionalized tetrakis(phenylethynyl)benzenes (TPEBs) and bis(dehydroben-zoannuleno) benzenes (bisDBAs) have been determined by using ZINDO-SOS method. The influence of the molecular structures on OPAs and TPAs have been discussed. Among the donor/acceptor substituted regioisomers, the ortho- and meta-substituted compounds have the largest two-photon responses, mainly due to the existence of the larger dipole moment differences between the ground states and the intermediate states. The diacetylene bridges in bisDBAs result in the red-shift of OPAs and TPAs and decrease of TPA cross-sections. From the point of view of transparency/nonlinearity, the TPEBs and bisDBAs are promising candidates for TPA materials.