基于二茂铁的两个查尔酮衍生物的合成及超快三阶非线性光学响应

二茂铁是合成新颖有机功能材料的基本单元之一。 本文设计并合成了两个基于二茂铁的同分异构查尔酮衍生物:1-二茂铁基-3-(噻吩-2-基)丙烯酮(a)和1-二茂铁基-3-(噻吩-3-基)丙烯酮(b)。 采用超快激光Z-扫描技术(脉宽180 fs,波长532 nm)测定了化合物a和b的三阶非线性光学性质。 结果表明,化合物a吸收系数β=-2.1×10^-12 m/W,折射率n₂=1.9×10^-19 m²/W,分子超极化率γ=5.37×10^-32 esu;化合物b:β=-1.2×10^-13 m/W,n₂=2.0×10^-19 m²/W,γ=4.48×10^-32 esu。 说明在飞秒激光激发下,电荷转移能够在化合物a和b分子内部快速进行,二者均具有优异的超快三阶非线性光学响应。 在B3LYP/6-311+G(d,p)理论水平下,计算了化合物a和b分子轨道能量、极化率和各基团在前线分子轨道中的占有率。 理论计算结果显示,二茂铁基团在化合物a和b前线分子轨道中占有率分别为97%和98%,对两化合物的非线性光学性能起主导作用。

Synthesis of Two Ferrocene-Based Chalcone Derivatives and Their Ultrafast Third-Order Nonlinear Optical Response

Two ferrocene-based isomeric chalcone derivatives 1-ferrocenly-3-(thiophen-2-yl) prop-2-en-1-one(a) and 1-(ferrocenly)-3-(thiophen-3-yl) prop-2-en-1-one(b) were synthesized. Their third-order nonlinear optical properties were measured by Z-scan technique with ultrafast laser operating at 532 nm laser in 180 fs pulse, respectively. The relevant parameters were given as follows: the nonlinear absorption coefficient β=-2.1×10^-12 m/W, the nonlinear refractive index n₂=1.9×10^-19 m²/W and the third-order nonlinear hyperpolarizability γ=5.37×10^-32 esu for compound a; β=-1.2×10^-13 m/W, n₂=2.0×10^-19 m²/W and γ=4.48×10^-32 esu for compound b. The results indicate that the excitation of femtosecond laser enables intramolecular charge transfer to occur quickly. Thus two compounds can exhibit ultrafast third-order nonlinear optical response. The orbital energies, polarizabilities and possession ratios of different groups in frontier molecular orbitals of compounds a and b were calculated by B3LYP/6-311+G(d,p) level. The percentage of ferrocene group in the frontier molecular orbitals of compounds a and b is 97% and 98%, respectively, which indicates that ferrocene group plays a leading role in the nonlinear optical properties of two compounds.