A novel indole based NNN donor Schiff base ligand and its Ni(II), Zn(II) and Cd(II) complexes have been synthesized using sonication-assisted method which is a highly efficient eco-friendly mechanism. The synthesized complexes have been characterized using elemental analysis, UV–Vis spectroscopy, mass spectrometry, FT-IR, and NMR and are optimized using DFT approach, which provided their theoretical framework. The stoichiometry between the ligand and the metal ions was also determined using Job's method. The thermogravimetric (TGA/DSC) analyses confirm the stability for all complexes at room temperature followed by thermal decomposition in different steps. DNA binding activities have been assessed by employing UV–visible and fluorescence spectra using the CT-DNA. The estimated intrinsic binding constant (K) for , , and complexes was 6.00 × 10, 5.58 × 10, and 4.7 × 10, respectively. In accordance with the K value, the quenching constant (K) values of , , and are 5.59 × 10 M, 4.3 × 10 M, and 4.08 × 10 M respectively. The anticancer properties have been assessed using MTT Assay. It has been found that the Ni(II) complex () is the most potent among the series with IC of 169 µg/mL. An in-vitro antioxidant experiment using DPPH was used to evaluate the synthesizedcomplexes' ability to scavenge free radicals. The findings indicated that the complexes exhibited notable antioxidant properties. The antioxidant property ZnL has been found to be the highest with an IC of 2.91 µg/mL and it follows the order is > > > L. Using the egg albumin denaturation technique, the anti-inflammatory property have been assessed, and the amount of protein denaturation inhibition has been computed. has the highest % inhibition among the series studied. Comparatively, the metal complexes have been reported to exhibit higher biological activities than the prepared Schiff base ligand. The reason for the excellent biological properties observed in the metal complexes could be attributed to the incorporation of the electron-withdrawing CHCOO during complexation. Molecular docking studies have been performed on the 2GYT protein and it has been found that the complexes have excellent binding affinity, with having the lowest binding energy of −6.93 Kcal mol. The values suggested that is more effective against HePG2 cancer cells, which is also in accordance with the MTT Assay results.

中文翻译：

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基于吲哚的NNN供体希夫碱配体及其复合物：超声辅助合成、表征、DNA结合、抗癌评估和体外生物测定

采用高效环保的超声辅助方法合成了一种新型吲哚基NNN供体席夫碱配体及其Ni(II)、Zn(II)和Cd(II)配合物。合成的配合物已使用元素分析、紫外-可见光谱、质谱、FT-IR 和 NMR 进行了表征，并使用 DFT 方法进行了优化，这提供了其理论框架。配体和金属离子之间的化学计量也使用乔布法测定。热重 (TGA/DSC) 分析证实了所有配合物在室温下的稳定性，然后在不同步骤中进行热分解。 DNA 结合活性已通过使用 CT-DNA 的紫外可见光谱和荧光光谱进行了评估。 、 和 复合物的估计内在结合常数 (K) 分别为 6.00 × 10、5.58 × 10 和 4.7 × 10。按照K值， 、 、 、 的淬火常数（K）值分别为5.59×10 M、4.3×10 M、4.08×10 M。抗癌特性已使用 MTT 测定进行评估。已发现 Ni(II) 络合物 () 是该系列中最有效的，IC 为 169 µg/mL。使用 DPPH 进行体外抗氧化实验来评估合成的复合物清除自由基的能力。研究结果表明，该复合物表现出显着的抗氧化特性。已发现 ZnL 的抗氧化性能最高，IC 为 2.91 µg/mL，其顺序为>>> L。使用卵清蛋白变性技术，评估了其抗炎性能，并确定了其添加量。已计算了蛋白质变性抑制。在所研究的系列中具有最高的抑制百分比。相比之下，据报道金属配合物比制备的席夫碱配体表现出更高的生物活性。在金属配合物中观察到优异的生物学特性的原因可能是由于在络合过程中引入了吸电子 CH3COO。对2GYT蛋白进行分子对接研究，发现复合物具有优异的结合亲和力，最低结合能为-6.93 Kcal mol。该数值表明对HePG2癌细胞更有效，这也与MTT测定结果一致。