Avance 3 hd 600 mhz nmr spectrometer

A Bruker Avance III HD 600 MHz NMR spectrometer equipped with a QCI 5 mm Cryoprobe and a SampleJet automated sample changer (Bruker BioSpin, Rheinstetten, Germany) was employed for 1D-NMR (¹H and ¹³C-NMR in CDCl₃) and 2D-NMR (correlation spectroscopy, COSY; heteronuclear multiple-bond correlation, HMBC; heteronuclear single-quantum correlation, and HSQC) spectroscopy. Chemical shifts are reported in parts per million (δ) using the residual CDCl₃ signal (δ_H 7.26; δ_C 77.2) as internal standards for ¹H and ¹³C NMR, respectively; coupling constants (J) are given in Hz.

The reagents and solvents
used in chemical synthesis were obtained from commercial agents without
further purification. All reactions were monitored by using thin-layer
chromatography (TLC). All final compounds were purified by a column
chromatography on silica gel (300–400 mesh). The NMR spectra
were recorded on an Agilent DD2 500 MHz, or a Bruker Avance III HD
600 MHz NMR spectrometer in DMSO-d₆. The
spectra of high-resolution mass (HRMS) were monitored by Bruker MaXis
4G TOF mass spectrometer and an ESI source. The purities of all final
compounds were identified by HPLC analysis with the Agilent 1200 system
and were proved to be >95%. HPLC condition: Triart C18 reversed-phase
column, 5 μm, 4.6 mm × 250 mm, and flow rate 1.0 mL/min,
starting with a 15 min-gradient from 0.1% TFA in water and acetonitrile
1:9 mixture to 0.1% TFA in acetonitrile, then ending with 0.1% TFA
in acetonitrile for 5 min.

One-dimensional (¹H, ¹³C, and distortionless enhancement by polarization transfer-135 (DEPT-135)) and two-dimensional (COrrelation SpectroscopY (COSY), heteronuclear single-quantum correlation (HSQC), and heteronuclear multiple-bond correlation (HMBC)) 600 MHz NMR measurements of the active purified compounds were carried out on a Bruker Avance III HD 600 MHz NMR spectrometer (Bruker, Billerica, MA, US). All HMBC measurements were done at the long-range (2–3 bonds) J(CH) coupling constant of 8.3 Hz. Based on differences in their solubilities, the compounds were dissolved in different proportions of acetone-d6 in D₂O. Compounds NMA2 (21 mg/mL), NMB4 (8.3 mg/mL), NMB6 (25 mg/mL), and NMC3 (15.4 mg/mL) were dissolved in 91, 75, 100 and 96.2% of acetone-d6 in D₂O (v/v), respectively [20 (link),21 (link),22 (link),23 (link),24 (link),25 (link)].

All NMR samples were derived from 100 mg pyrolysis oils dissolved in 1000 µL deuterated chloroform (CDCl₃-d₁). AVANCE III HD 600MHz NMR spectrometer (Bruker Inc., Zurich, Switzerland) was used to obtain ¹³C NMR spectra of pyrolysis oil generated under different conditions, with operating parameters set to 1500 scans and 3s pulse delay [19 (link),22 (link)]. For ¹H NMR, the operation parameters were set to 16 transients and 5 s pulse delay. All NMR spectra were processed by MestReNova v12.0 (Mestrelab Research, Santiago De Compostela, Spain).

Measurements of ¹H, ¹³C, distortionless enhancement by polarization transfer (DEPT) 135, correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple-bond correlation (HMBC) spectra were accomplished using an Avance III HD 600-MHz NMR spectrometer (¹H, 600.05 MHz; ¹³C, 150.88 MHz; Bruker BioSpin GmbH, Ettlingen, Germany). COSY, total correlation spectroscopy (TOCSY), and nuclear Overhauser effect spectroscopy (NOESY) spectra were recorded at 298 K on an Avance Neo 700-MHz NMR spectrometer equipped with a 5-mm CryoProbe Prodigy TCI (¹H, ¹⁵N, ¹³C Z-GRD; ¹H, 700.28 MHz; ¹³C, 176.09 MHz; Bruker BioSpin GmbH, Ettlingen, Germany) with H₂O suppression. All measurements were carried out using D₂O as solvent. Chemical shifts are given in parts per million (ppm). ¹H spectra were referenced to the residual solvent signal (δ = 4.79 ppm). For ¹³C measurements 3-(trimethylsilyl)propionic-2,2,3,3-d₄ acid sodium salt (TSPA, δ = 1.7 ppm) was used as an external standard. For a better resolution of the correlation signals, HSQC and HMBC spectra were additionally acquired using nonuniform sampling (NUS). Analysis of NMR spectra was achieved using the software TopSpin 3.6.0 (Bruker BioSpin GmbH, Ettlingen, Germany).