A critical theoretical study on linear and nonlinear optical properties of macrocyclic thiophene derivatives with different connecting π-conjugated bridge and ring size

This contribution reports the geometries, electronic structures, linear and nonlinear optical properties of a series of macrocyclic thiophene derivatives with different connecting π-bridge and ring size in theory. It provides great optical properties that both OPA and TPA peaks shift red as Ne increases and in different window, which don't superimpose on each other, and the values of δ(1)max and δ(2)max enlarge, while the largest δ(2)max for C[6T_A_E]3 observed at long wavelength (725.9 nm) is 23 times larger than that of the unit C[6T_A_E]. Besides connecting bridge and ring size, several key parameters essentially influencing on NLO property were highlighted, including M0k, Mkn, ƒ0k × ƒkn and Ne. In addition, ICT impacting on the values of δ(2)max was analyzed by contour surfaces of the frontier orbitals and ΔQ of thiophene and bridge. More particularly, large negative value of Reγ indicates their self-defocusing, implying it can be applied in self-defocusing optical power limiting materials.

Highlights► Both OPA and TPA peaks shift red as Ne increases and in different window. ► δ(1)max and δ(2)max enlarge as the ring size increases. ► The values of M0k, Mkn, ƒ0k × ƒkn and Ne play important roles on NLO property. ► ICT impacting on δ(2)max was analyzed by frontier molecular orbital diagram and ▵Q. ► They can be applied in two-photon self-defocusing optical power limiting materials.