Three new tetradentate NNNS Schiff bases (L1–L3) derived from 2-(piperidin-4-yl)ethanamine were prepared in high yields. UV–Visible and FTIR spectroscopy were used to monitor the dehydration reaction between 2-(piperidin-4-yl)ethanamine and the corresponding aldehydes. Structures of the derived Schiff bases were deduced by 1H and 13C NMR, FTIR, UV–Vis, MS, EA, EDS, and TG-derived physical measurements. DFT/B3LYP theoretical calculations for optimization, TD-DFT, frequency, Molecular Electrostatic Potential (MEP), and highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) / were performed for L2. The in vitro antimicrobial activities of the three Schiff bases were evaluated against several types of bacteria by disk diffusion test using Gentamicin as the standard antibiotic. Schiff bases revealed good antioxidant activity by the DPPH method, and the IC50 values were compared to the Trolox standard. Pancreatic porcine lipase inhibition assay of the synthesized compounds revealed promising activity as compared to the Orlistat reference.

中文翻译：

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具有 2-(哌嗪-1-基)-N-(噻吩-2-基亚甲基)乙胺部分作为新型胰腺脂肪酶抑制剂的三种希夫碱的合成和光谱鉴定：热、DFT、抗氧化、抗菌和分子对接调查

以高产率制备了源自 2-(哌啶-4-基)乙胺的三种新的四齿 NNNS Schiff 碱 (L1-L3)。紫外-可见光和 FTIR 光谱用于监测 2-(哌啶-4-基)乙胺和相应醛之间的脱水反应。衍生的席夫碱的结构通过 1H 和 13C NMR、FTIR、UV-Vis、MS、EA、EDS 和 TG 衍生的物理测量推导出来。对 L2 进行了用于优化、TD-DFT、频率、分子静电势 (MEP) 和最高占据分子轨道 (HOMO) 和最低未占据分子轨道 (LUMO) 的 DFT/B3LYP 理论计算。使用庆大霉素作为标准抗生素，通过圆盘扩散试验评估了三种席夫碱对几种细菌的体外抗菌活性。Schiff 碱通过 DPPH 方法显示出良好的抗氧化活性，并将 IC50 值与 Trolox 标准进行比较。合成化合物的胰腺猪脂肪酶抑制测定显示与奥利司他参考相比有希望的活性。