Thermo nicolet 5700 ftir spectrometer

UV-visible spectra of samples diluted in MeOH were obtained using a Jasco V770 UV/Vis spectrophotometer (JASCO GmbH, Pfungstadt, Germany). IR spectra were recorded with a Thermo Nicolet 5700 FT-IR spectrometer (Thermo Electron Corporation, Langenselbold, Germany). The HR-MS measurements were performed on a SciexTripleTOF 6600 LC-MS spectrometer (AB Sciex, Darmstadt, Germany) with an Acquity UPLC System (Waters GmbH, Eschborn, Germany) equipped with EC 150/2 NUCLEOSHELL RP18 column (150 × 2 mm, particle size 2.7 µm). The samples were measured in the negative and positive ion modes. 1D and 2D NMR spectra were recorded on a Varian/Agilent 400 and 600 NMR spectrometer (Agilent Technologies, Santa Clara, CA, USA). CD₃OD and C₅D₅N were used as NMR solvent. Chemical shifts (δ) are referenced to internal tetramethylsilane (TMS) (δ = 0 ppm, ¹H) and internal CD₃OD (δ = 49.0 ppm, ¹³C) or internal pyridine-d5 (δ = 123.5 ppm, ¹³C). Thin-layer chromatography was performed on Merck pre-coated silica gel 60 F₂₅₄ aluminum foil plates (Merck, Darmstadt, Germany). Spots were detected on TLC under UV lamp (254 and 365 nm) or by heating to 100 °C after spraying with vanillin sulfuric solution. Eluting solvents (MeOH, CHCl₃, EtOAc) were distilled before use.