Ultrashield 500 spectrometer

Nuclear magnetic resonance (NMR) spectra
were recorded at 298 K on a Bruker Avance III spectrometer operating
at a ¹H frequency of 500.13 MHz and featuring a BBI probe
and a Bruker UltraShield 500 spectrometer operating at a ¹H frequency of 500.13 MHz. Chemical shifts (δ) are given in
parts per million (ppm), and the residual solvent peak was used as
an internal standard (CDCl₃: δH = 7.24 ppm and C₆D₆: δH = 7.16 ppm). For the quantitative
1D ¹H measurements, 64k data points were sampled with the
spectral width set to 16 ppm and a relaxation delay of 30s. Quantification
was done using the Digital ERETIC method.^{84 (link)} Chemical shifts for ³¹P spectra were referenced indirectly
to the ¹H NMR frequency of the sample with the xiref-macro
in Bruker.

NMR spectra were recorded on a Bruker Ultrashield 500 spectrometer equipped with a 5-mm TCI cryoprobe (¹H at 500 MHz, ¹³C at 125 MHz). For HMBC, HSQC, and COSY experiments, standard pulse programs were used and HMBC experiments were optimized for ^2,3J_C-H = 6 Hz. All observed chemical shift values (δ) are given in ppm and coupling constant values (J) in Hz. Chemical shifts of the remaining nondeuterated methanol solvent signals at δ_H 3.31 ppm and δ_C 49.2 ppm were used as reference signals for spectrum calibration. To increase sensitivity, the measurements were performed in a 5-mm Shigemi tube (Shigemi Inc., Allison Park, PA, USA). Processing and data evaluation were carried out using the ACD/NMR Workbook Suite Enterprise 2019.

The phase purity and the crystallinity of the samples were obtained via powder X-ray diffraction analysis on a Shimadzu XRD-7000S diffractometer fitted with Cu Kα radiation (λ = 1.5418 Å) operating at 40 mA and 40 kV. The morphology of the particles was analysed via scanning electron microscopy (SEM, Nova Nano SEM 450) and transmission electron microscopy (TEM, Tecnai F30, FEI). Moreover, the textural properties of the calcined samples were determined via nitrogen physisorption at 77 K by using an Autosorb-iQ-C adsorption analyser (Quantachrome Instruments). The surface area was calculated by employing the Brunauer–Emmett–Teller (BET) method. A series of ¹³C solid-state cross polarization magic-angle spinning (CP-MAS) NMR measurements was conducted on a Bruker Ultrashield 500 spectrometer at the MAS frequencies. The ¹³C CP/MAS NMR spectra were recorded by collecting 2000 scans at a spinning rate of 10 kHz with a contact time of 4 ms and a recycle delay of 4 s. The chemical shifts were referenced to adamantane with the upfield methine peak set to 29.5 ppm. A thermogravimetric analysis (TGA) was performed by using a Mettler-Toledo TGA/DSC1-MS thermal analyser with a heating rate of 10°C min⁻¹ in air.

Nuclear magnetic resonance (NMR) measurements were recorded at 298 K on a Bruker UltraShield 500 spectrometer operating at a frequency of 500.13 MHz. The IR spectra were recorded on a PerklinElmer spectrum 2 ATR-FTIR with a diamond crystal.

Nuclear Magnetic Resonance
(NMR) measurements were recorded at 298K on Bruker UltraShield 500
spectrometer operating at a frequency of 500.13 MHz. ³¹P spectra were acquired using inverse gated decoupling, a delay time
of 1 s and 64 scans. The ³¹P spectra were processed with
a line broadening of 5 Hz. Spectra acquired with a delay of 5 s gave
identical relative integrations. Transmission electron microscopy
(TEM) images (of a drop-cast suspension on a Holey Carbon Film–Cu
grid) were taken on FEI Talos F200C TEM with 200 kV FEG optics.