Synthesis of Bis(N,N-diethyl)aniline-Based, Nonlinear, Optical Chromophores with Increased Electro-Optic Activity by Optimizing the Thiolated Isophorone Bridge

Abstract

Six nonlinear, optical chromophores, Z1–Z6, based on the bis(N,N-diethyl)aniline-derived donor and thiolated isophorone bridge, were designed and synthesized. The bis(N,N-diethyl)aniline-derived donor was applied in a chromophore with thiolated isophorone as an electron bridge for the first time. In particular, the bridge parts of chromophores Z2–Z6 were modified with different functional groups, including tert-butyltrimethylsilane and tert-butyl(methyl)diphenylsilane derivative: 1,3-bis(trifluoromethyl)benzene and alkylaniline cyanoacetate, respectively. Density functional theory calculations suggested this series of chromophores show much greater hyperpolarizability than traditional, nonlinear, optical chromophores due to strong electron donor ability. These chromophores, Z1–Z6, showed very high poling efficiencies due to the large steric hindrance and hyperpolarizability of the chromophores. A large poling efficiency (2.04 ± 0.08 nm2/V2) and r33 value (193 pm/V) were achieved for polymeric thin films doped with 25 wt% chromophore Z6 at 1310 nm.