In this work, the structural, electronic, and optical features of quinoline derivatives were carried out by experiment and density functional theory (DFT). Our results show that a change in the substitution position of methyl group (CH₃) gives rise to a decrease in the bandgap of quinoline derivatives from 2.75 to 2.50 eV for 2-Chloro-5,7-dimethylquinoline-3-carboxaldehyde (C7DMQCA) and 2-Chloro-5,7-dimethylquinoline-3-carboxaldehyde (C8DMQCA), respectively. From dipole moment, the C7DMQCA has stronger intermolecular interaction which is comparable with the bandgap energies. The absorbance maxima are found between 313 nm (3.96 eV) and 365 nm (3.39 eV) for C7DMQCA and C8DMQCA. The refractive index and optical conductivity of the C7DMQCA are found to be higher than that of the C8DMQCA. Besides, the transmittance, angle of incidence and refraction, and (αhϑ)²curves were investigated in detail. Theoretical predictions are also compatible with experimental findings. The study shows the C7DMQCA has desirable properties such as lower optical bandgap, higher refractive index, and optical conductivity than the C8DMQCA.

中文翻译：

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结合实验和DFT / TD-DFT研究喹啉衍生物的电子结构，结构和光学性质。

在这项工作中，通过实验和密度泛函理论（DFT）进行了喹啉衍生物的结构，电子和光学特征的研究。我们的结果表明，甲基（CH ₃）会使2-氯5,7-二甲基喹啉-3-甲醛（C7DMQCA）和2-氯-5,7-二甲基喹啉-3-甲醛（C8DMQCA）的喹啉衍生物的带隙从2.75 eV降低到2.50 eV ）， 分别。从偶极矩开始，C7DMQCA具有更强的分子间相互作用，可与带隙能量媲美。发现C7DMQCA和C8DMQCA的最大吸光度在313 nm（3.96 eV）和365 nm（3.39 eV）之间。发现C7DMQCA的折射率和光导率高于C8DMQCA的折射率和光导率。此外，透射率，入射角和折射角以及（αhϑ）²曲线进行了详细研究。理论预测也与实验结果兼容。研究表明，与C8DMQCA相比，C7DMQCA具有令人满意的特性，例如更低的光学带隙，更高的折射率和更高的光导率。