400 mhz ft nmr spectrometer

¹H-NMR spectra were recorded on a 400 MHz FT-NMR spectrometer (Bruker, Billerca, MA, USA) at room temperature. ¹H-NMR data are reported in parts per million (ppm) as chemical shift values relative to tetramethylsilane (TMS) as the internal standard. All NMR spectra were recorded in CDCl₃. GPC data were recorded using an HP-1047A system (Hewlett Packard, Palo Alto, CA, USA). High performance liquid chromatography (HPLC)-grade THF was used as the eluent, which was maintained at 40 °C. The flow rate was 2.0 mL/min, and the injection volume was 30 μL. The calibration was based on polystyrene standards obtained from American Polymer Standards Co. All polymer samples were dissolved in HPLC-grade THF. DSC curves were obtained using a DSC N-650 instrument (Scinco, Seoul, Korea). All the samples were first heated to 300 °C for 10 min to eliminate their thermal history and then cooled to room temperature. The heating and cooling scans were performed at a rate of 10 °C/min.

All reagents were of analytical grade and were used directly. Thin-layer chromatography (TLC) was performed on silica gel plates (60 F254; Merck). Melting points were determined using an open capillary method on a Buchi apparatus and are uncorrected. IR spectra were recorded on a Nicolet 6700 FT-IR instrument (Nicolet, Madison, WI, USA) using KBr pellets. ¹H and ¹³C NMR spectra were recorded on Bruker 400 MHz FT NMR spectrometer using CDCl₃ and DMSO-d₆ as solvent and TMS as internal standard. All chemical shifts were reported as δ values (ppm). Mass spectra were recorded using Shimadzu GCMSQP2010S. The elemental analysis was carried out using Hereaus CHN rapid analyser. Microwave irradiation synthesis was carried out under CEM-Discover Focused Microwave system. Purity of the compound was checked by TLC.

Commercial chemicals and solvents were used without purification. NMR spectra were measured on a Bruker 400 MHz FT-NMR spectrometer (Bruker, Falladen, Switzerland) using DMSO-d₆ as solvent. HRESI mass spectra were recorded at the Department of Chemistry at the University of Singapore on a MAT 95 x1-T spectrometer at 70 eV (Agilent Technologies, Santa Clara, CA, USA). Melting points were determined using a Mel-Temp II melting point apparatus (Laboratory Devices Inc., Holliston, MA, USA) and are uncorrected. IR spectra were recorded on a RX1 FT-IR spectrometer (Perkin-Elmer, Waltham, MA, USA). The absorbance of the reaction mixtures in the DPPH and FRAP assays were determined by UV spectroscopy using a Power Wave X340, BioTek Inc, Instrument (Winooski, VT, USA). The detailed spectrums and analyze are available in Supplementary Materials.