Giant enhancement of the nonlinear optical properties of [2.2]paracyclophanes by an donor-bridge-acceptor

Abstract

Recently, the modulating the charge transfer of the donor-S-acceptor (DSA) has been proven as an appropriate method to increase the static first hyperpolarizability of the molecule. In this work, we employ the extended π-conjugated bridge to further explore the charge transfer effect on the nonlinear optical response, where (CHCH)nNH2 and (CHCH)nNO2 are served as an donor group and acceptor group, respectively. Electrostatic potentials on the molecular surface of all molecules indicate that charge transfer is found from donor group to acceptor group, which indicates that these molecules may be excellent nonlinear optical materials. The calculations proves that these molecules exhibit large first hyperpolarizability in the range of 3485−46199 au. Compared with short chain, long chain brings these molecules the large first hyperpolarizability, which are 146199 au for n = 4. Moreover, the ultraviolet-visible-infrared indicate that the molecule is transparent in the deep-ultraviolet, which may be regarded as a new candidate for deep ultraviolet nonlinear optical materials. The transition can give reasons for the change in the first hyperpolarizability of these molecules. We hope that this paper can provide new insights for the design of nonlinear optical materials.