Dyestuff Technology Department, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai 400019, India.
Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram, Kerala 695015, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Feb 5;246:119017. doi: 10.1016/j.saa.2020.119017. Epub 2020 Sep 30.
The Z-scan and DFT techniques were explored to investigate the non-linear optical properties of anthraquinone fused imidazole-based D-π-A dyes. With the help of UV-visible spectral analysis, pH study, CV analysis, HOMO-LUMO interaction, MEP plots, and quinoidal character the influence of intramolecular charge transfer characteristics and H-bonding process on electronic and photophysical studies of anthraquinone derivatives were understood. The dyes 2-(4-(diethylamino)-2-hydroxyphenyl)-3H-anthra[1,2-d]imidazole-6,11-dione (AQ1) and 2-(2-hydroxynaphthalen-1-yl)-1H-anthra[1,2-d]imidazole-6,11-dione (AQ2) displayed a single emission with pronounced Stokes shift and thermal stability (upto 290 °C). The dye AQ1 exhibited strong charge transfer character which is explained by the ICT process leading to high nonlinear susceptibility χ in AQ1 3.43 × 10 e.s.u relative to the dye AQ2 which has only ESIPT core. But, the dye AQ2 6.27 J cm showed better optical limiting value. The NLO properties of AQ1 and AQ2 were computed by DFT functionals based on Hartree Fork (HF) percentage exchange. The dye AQ1 exhibits noticeable NLO properties. The global hybrid functionals with HF composition beyond 50% (BHHLYP, M06-HF) and the long rang corrected functionals (CAM-B3LYP, ωB97, and ωB97X) demonstrated comparable NLO properties relative to B3LYP and PBE0. It was observed that the combined effect of ICT and the H-bonding cores enhance the NLO properties. The experimental findings (Z-scan) were successfully correlated with theoretical (DFT) results.
采用 Z 扫描和密度泛函理论（DFT）技术研究了蒽醌并咪唑基 D-π-A 染料的非线性光学性质。通过紫外-可见光谱分析、pH 研究、CV 分析、HOMO-LUMO 相互作用、MEP 图和醌型特征，了解了分子内电荷转移特性和氢键过程对蒽醌衍生物电子和光物理研究的影响。染料 2-(4-(二乙基氨基)-2-羟基苯基)-3H-蒽[1,2-d]咪唑-6,11-二酮（AQ1）和 2-(2-羟基萘-1-基)-1H-蒽[1,2-d]咪唑-6,11-二酮（AQ2）均显示出单一发射，具有明显的Stokes 位移和热稳定性（高达 290°C）。染料 AQ1 表现出强烈的电荷转移特性，这可以通过 ICT 过程来解释，导致 AQ1 的非线性磁化率 χ 为 3.43×10 e.s.u，而仅具有 ESIPT 核的染料 AQ2 的 χ 为 2.15×10 e.s.u。但是，染料 AQ2 的光学限制值为 6.27 J cm。通过基于哈特ree-fork（HF）交换百分比的 DFT 函数对 AQ1 和 AQ2 的 NLO 性质进行了计算。染料 AQ1 表现出显著的 NLO 性质。HF 成分超过 50%的全局混合泛函（BHHLYP、M06-HF）和长程校正泛函（CAM-B3LYP、ωB97、ωB97X）与 B3LYP 和 PBE0 相比表现出相当的 NLO 性质。观察到 ICT 和氢键核的综合作用增强了 NLO 性质。实验结果（Z 扫描）与理论（DFT）结果成功相关。
