Computational study of the one- and two-photon absorption properties of macrocyclic thiophene derivatives

Abstract

The geometrical structure, electronic structure, one-photon and two-photon absorption properties of a series of macrocyclic thiophene derivatives C[3T_DA] n ( n = 2–5) have been studied using density functional theory (DFT) and Zerner’s intermediate neglect of differential overlap (ZINDO) methods theoretically. The results showed that the range of λ (1) maxs is 390–470 nm and λ (2) maxs is 640–670 nm, while, both λ (1) max and λ (2) max gradually enlarge as increasing the number of the C[3T_DA] unit. And C[3T_DA] n compounds exhibited large TPA cross-section ( δ max), and the factors influencing on the δ max values were analyzed in detail. Transition dipole moments M 0k and M kn play important roles on δ max. Both π-electron number ( N e) and the product of oscillator strengths from ground state to mediate state (ƒ 0k) and from mediate state to final state (ƒ kn) are in proportion to δ max. Moreover, δ max linearly depends on the static second-order nonlinear optical susceptibilities ( β 0).