4个芘基查尔酮衍生物的合成及超快三阶非线性光学响应

Synthesis of four pyrenyl chalcone derivatives and their ultrafast third-order nonlinear optical response

本文合成了4个D-A-π-D型芘基查尔酮衍生物:1-(芘-1-基)-3-(3,4-二甲氧基苯基)丙烯酮(3a)、1-(芘-1-基)-3-(3,4,5-三甲氧基苯基)丙烯酮(3b)、1-(芘-1-基)-3-(3,5-二甲氧基苯基)丙烯酮(3c)及1-(芘-1-基)-3-(2,4-二甲氧基苯基)丙烯酮(3d).采用差示扫描量热法测定了它们的DSC/TG曲线.通过紫外光谱、荧光光谱和Z-扫描技术方法分别研究了它们的线性光学性质和三阶非线性光学吸收.实验表明,在532 nm和180 fs条件下,化合物3a-3d均表现出超快三阶非线性光学响应,化合物3b的非线性吸收系数分别是化合物3a,3c和3d的11,1.2和12.8倍.运用密度泛函理论方法计算了化合物3a-3d的非线性光学性质及其电子性质,结果表明化合物3b具有最大极化率(6.42×10^(-39) C^(2)·m^(2)·J^(-1))和超极化率(6.48×10^(-50) C^(3)·m^(3)·J^(-2)),并具有最小的Egap(3.1660 eV)和跃迁能ΔE(2.8442 eV),这与苯环上连的三甲氧基有关,且化合物3a-3d内部均存在电荷转移现象.

The research of organic nonlinear optical(NLO)materials has become a hot topic in the fields such as optical communication,optical limiting,data storage,optical switch,dynamic holography and so on,which makes the molecular design and synthesis of various organic nonlinear optical materials more and more important.Many studies show that the introduction of electron donor(D)and electron acceptor(A)into chalcone molecules can readjust the electron cloud density ofπ-conjugated system,which has an important impact on its photophysical properties and may eventually be applied in industrial fields.In addition,the NLO activity of chalcone derivatives can be predicted from D/A substitution,and the nonlinear optical behavior of chalcone derivatives can also be improved by changing different D/A by means of theoretical calculation.In chalcone family,pyrene-containing chalcone derivatives are unique.Pyrene group is a fluorophore with good thermodynamic stability and large rigid conjugation plane.Its strong electron donating ability makes it a good candidate groups of nonlinear optical materials.However,there are few studies on the nonlinear optical properties of chalcones containing pyrene group and polymethoxyphenyl.In this work,four pyrenyl chalcone derivatives 1-(pyren-1-yl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one(3 a),1-(pyren-1-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one(3 b),1-(pyren-1-yl)-3-(3,5-dimethoxyphenyl)prop-2-en-1-one(3 c)and 1-(pyren-1-yl)-3-(2,4-dimethoxyphenyl)prop-2-en-1-one(3 d)were synthesized.Their thermal stability was measured by differential scanning calorimetry.The linear optical properties and third-order nonlinear optical absorption were studied by UV-Vis spectra,fluorescence spectra and Z-scan technique,respectively.The experiments show that 3 a-3 d are all able to exhibit ultrafast third-order nonlinear optical response with 180 fs laser pulse at 532 nm.The nonlinear absorption coefficient of 3 b is 11,1.2 and 12.8 times that of 3 a,3 c and 3 d,respectively.The nonlinear optical properties and electron transitionic properties of 3 a-3 d were calculated by density functional theory.The results indicate that the target molecule 3 b possess the largest polarizability(6.42×10^(-39 )C^(2)·m^(2)·J^(-1)),the largest hyperpolarizability(6.48×10^(-50 )C^(3)·m^(3)·J^(-2)),the smallest energy gap between HOMO and LUMO(3.166 eV)and the smallest transition energyΔE(2.844 eV),which is related to the the trimethoxy group attached to the benzene ring.The experimental results are in good agreement with the theoretical calculation ones.In comparison,there are three methoxyl groups in the aromatic ring of the molecule 3 b.As a result,the electron donating ability of trimethoxyphenyl is more concentrated and powerful,and the conjugated electron system is larger.This indicates that 3 b is easier to be polarized,and it has larger polarizability,hyperpolarizability and third-order nonlinear optical absorption,showing a better ultrafast third-order nonlinear optical response.This study can promote the development of third-order nonlinear optical materials.