Muhammad Shabbir, Al-Sehemi Abdullah G, Irfan Ahmad, Chaudhry Aijaz R, Gharni Hamid, AlFaify S, Shkir Mohd, Asiri Abdullah M
Department of Physics, College of Science, King Khalid University, P.O. Box 9004, Abha, 61413, Saudi Arabia.
Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. Box 9004, Abha, 61413, Saudi Arabia.
J Mol Model. 2016 Apr;22(4):73. doi: 10.1007/s00894-016-2946-8. Epub 2016 Mar 12.
Using the state-of-art computational techniques, we limelight a structure-property relationship for the position and number of methoxy group(s) to tune the optical and nonlinear optical (NLO) properties (first hyperpolarizability) of chalcone derivatives. Based on our previously synthesized chalcones [system 1 ((E)-1-(2,5-dimethylthiophen-3-yl)-3-(2-methoxyphenyl)prop-2-en-1-one and system 4 (E)-1-(2,5-dimethylthiophen-3-yl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one)], we systematically design several novel derivatives with tuned optical and NLO properties. For instance, the rotation of methoxy group substitutions at three different possible ortho, meta, and para positions on phenyl ring show significant changes in NLO properties of these chalcones derivatives. The system 3 has shown β tot amplitude of 1776 a.u. with terminal 4-methoxyphenyl group (para-methoxy substitution), which is ~2.2 and 2.4 times larger than that of ortho- and meta-methoxyphenyl systems 1 and 2, respectively. Additionally, systems 3a and 4a, which are cyano derivatives of the systems 3 and 4 show significantly large β tot amplitudes of 3280 and 4388 a.u., respectively, which are about 3 and 4 times larger than that of para-nitro aniline (PNA) molecule (a typical donor-acceptor molecule) at the same LC-wPBE/6-311G** level of theory. The origin of larger β tot amplitudes has been traced in lower transition energies and higher oscillator strengths for crucial transitions of designed derives. Thus, our investigation reveals that the chalcones derivatives with para-methoxyphenyl groups possess reasonably large amplitudes of their first hyperpolarizability and good optical transparency (3.0-4.7 eV), which can make them attractive candidates for nonlinear optical applications.
运用最先进的计算技术，我们揭示了甲氧基的位置和数量与查尔酮衍生物的光学和非线性光学（NLO）性质（第一超极化率）之间的结构-性质关系。基于我们之前合成的查尔酮[体系1（（E）-1-（2,5-二甲基噻吩-3-基）-3-（2-甲氧基苯基）丙-2-烯-1-酮）和体系4（（E）-1-（2,5-二甲基噻吩-3-基）-3-（2,4,5-三甲氧基苯基）丙-2-烯-1-酮）]，我们系统地设计了几种具有可调光学和NLO性质的新型衍生物。例如，苯环上三个不同的邻位、间位和对位上甲氧基取代基的旋转显示出这些查尔酮衍生物的NLO性质有显著变化。体系3中，带有末端4-甲氧基苯基（对位甲氧基取代）时，β总振幅为1776 a.u.，分别比邻位和间位甲氧基苯基体系1和2大~2.2倍和2.4倍。此外，体系3a和4a分别是体系3和4的氰基衍生物，其β总振幅分别显著高达3280和4388 a.u.，在相同的LC-wPBE/6-311G**理论水平下，分别约为对硝基苯胺（PNA）分子（典型的供体-受体分子）的3倍和4倍。较大β总振幅的来源可追溯到所设计衍生物关键跃迁的较低跃迁能量和较高振子强度。因此,我们的研究表明，带有对位甲氧基苯基的查尔酮衍生物具有相当大的第一超极化率振幅和良好的光学透明度（3.0 - 4.7 eV），这使其成为非线性光学应用中有吸引力的候选材料。
