新型苯并噻二唑衍生物的非线性光学性质理论研究

Theoretical study of the nonlinear optical properties of new benzothiadiazole derivatives

以苯并噻二唑分子为母体,设计了5个系列的衍生物,采用AM1半经验量子化学方法,研究了共轭π桥的不同增长方式和不同推拉电子基团对分子的电子结构及非线性光学性质的影响.结果表明:共轭链较短时,分子的二阶极化率和三阶极化率与共轭链长的线性相关性较好;而当共轭链较长时,分子的二价极化率和三阶极化率随着共轭链的增长而呈起伏性变化;与三氰基呋喃相比,三硝基呋喃对非线性极化率的影响更大;部分目标分子的一阶极化率α与Δμ·ΔE-1、二阶极化率β与α·ΔE-1、三阶极化率γ与α·ΔE-2和β·ΔE-1都有较好的相关性.

The nonlinear properties of five series of benzothiadiazole derivatives were calculated by semi-empirical finite filed/AM1 method. The calculation results show that： （1） For the title mole- cules with short π-conjugated bridge, there was a good linear correlation between polarizalbilities and π-conjugated length. For the title molecules with longer π-conjugated bridge, the hyperpolarizability of the title molecules was undulating increase with the increase of π-conjugated bridge. （2） Trinitrofu ran performed well than Tricyanofuran on electron withdrawing ability and then has a greater impact on the hyperpolarizability of title molecules. （3） The relationship of first-order polarizability a of the partial molecules with △μ. △E -1 , second-order hyperpolarizability β of the partial molecules with α· △E-1 , third-order hyperpolarizability γ with α· △E -2 and β ·△E-1 was a good correlation.