含呋喃共轭桥有机非线性光学生色团的合成及性能研究

通过两次羟醛缩合反应合成了一种含呋喃共轭桥的有机非线性光学生色团分子2-二氰亚甲基-3-氰基-4-2-(4-二乙氨基-苯乙烯基-呋喃基-5)-乙烯基]-5,5-二甲基-2,5-二氢呋喃(EFFC), 用IR谱、¹H NMR谱以及元素分析表征确认了其结构. 热失重分析表明, 材料的热分解温度T_d为250℃. 用密度泛函理论的B3LYP方法在6-31G基组下对这种生色团分子进行了结构优化, 并在相同基组下对分子的静态二阶极化率进行了计算, 分子的b₀=6.5×10^-28 esu. 将分子以18%的质量比与聚砜进行主-客体掺杂, 用溶胶凝胶法制备成膜后进行极化, 用二次谐波法对掺杂极化聚合物薄膜的电光系数进行测量, 其r₃₃值最高达到80 pm/V.

Synthesis and Properties of Novel Organic Nonlinear Optical Chromophores Containing Furan Conjugating Bridges

A novel nonlinear optical(NLO) chromophore 2-{2-(4-diethylamino-styreneyl)-furyl-5]-vinyl}-3-cyano-5,5dimethyl-5H-furan-2-ylidene]malononitrile(EFFC) containing furan conjugating bridge was designed with tricyanofuran as electron acceptors and dialkylamine as donors.The molecular has been synthesized via two steps of aldol condensation reactions.In the first step,5-methylfurfural(1 equiv.) and drops of acetic acid in THF was added dropwise to a solution of 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran(TCF)(1 equiv.) and pyridine.After the addition,the mixture was stirred for 24 h at room temperature.The reaction mixture was filtrated and the insoluble residue was washed several times with ethanol.Secondly,the intermediate(1 equiv.),4-(diethylamino)benzaldehyde(1 equiv.) and ten drops of piperidine were dissolved in MeCN.The solvent was removed after heated to reflux for 24 h.The product EFFC was purified by a silica gel chromatograph column and characterized by FT-IR,1H NMR and elemental analysis.The thermal decomposition temperature(Td) as high as 250 ℃ was determined by TGA testing.Furyl conjugating bridges lowered the Tdcompared with the non-furyl corresponding structure DCDHF-2-V.Density functional theory(DFT) B3LYP/6-31G method was used to optimize the structures and calculate the static hyperpolarizability(β0).The β0 value of EFFC was calculated as large as 6.5×10-28esu.It was larger than the corresponding chromophores with dimethylamine donors.The chromophore was mixed into polysulfone(PSU) with the weight ratio of 18%.The mixture was dissolved in cyclohexanone and the films were spun onto ITO/glass substrates.The chromophores in the polymer matrix were aligned into a noncentrosymmetrical orientation by corona poling technique.The poling was performed in a wire-to-plane geometry under in-situ conditions.The discharging wire to plane distance was 1 cm.12 kV of corona voltage was applied and kept for 15 min at 100 ℃.The film was cooled down to the room temperature at applied electric field maintaining a constant current.The second-order nonlinear coefficient r33value reached to 80 pm/V at 1064 nm was measured by second harmonic generation method.