Pb 10 ph metre

The NMR experiments were performed on a Varian Infinity-plus 400 spectrometer operating at a magnetic field strength of 9.4 T. The resonance frequencies at this field strength were 161.9 and 104.2 MHz for ³¹P and ²⁷Al, respectively. A Chemagnetics 5 mm triple-resonance MAS probe with a spinning rate of 8 kHz was used to acquire the ³¹P and ²⁷Al NMR spectra. The ²⁷Al MAS spectra were acquired using a single pulse sequence with a short radio frequency (rf) pulse of 0.5 s (corresponding to a π/15 flip angle) and a pulse delay of 1.0 s. The pulse length for ²⁷Al was measured using a 1 M Al(NO₃)₃ solution. The single-pulse ³¹P MAS NMR experiments with ¹H decoupling were performed with a 90° pulse width of 4.6 ms, a 180 s recycle delay, and a ¹H decoupling strength of 42 kHz. The chemical shifts were referenced to an 85% H₃PO₄ solution for ³¹P and a 1 M Al(NO₃)₃ solution for ²⁷Al.
The powder X-ray diffraction (XRD) patterns were recorded on a Rigaku diffractometer that was equipped with a graphite monochromator using Cu Kα radiation (λ = 1.5418 Å). The pH values of the liquid phases were measured with a Sartorius PB-10 pH metre. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was performed on a Perkin-Elmer Optima 3300DV spectrometer.

R- or S-(1-phenylethylamino)methylphosphonic acid (pempH₂) was prepared according to methods reported in the literature^{38 (link)}. All other starting materials were of reagent grade and were used as received from commercial sources without further purification. Elemental analyses for C, H and N were carried out on a PE 240C analyser. IR spectra were recorded with a Bruker Tensor 27 spectrometer using KBr discs. The pH value was measured by a Sartorius PB-10 pH metre. Thermal analyses were performed under nitrogen in the temperature range of 25–800 °C at a heating rate of 5 °C min⁻¹ on a METTLER TOLEDO TGA/DSC 1 instrument. PXRD data were collected using a Bruker D8 advance diffractometer. SEM measurements were performed on SHIMADZU SSX-550. The UV–Vis spectra were recorded on Perkin Elmer Lambda 950 UV–Vis/NIR Spectrometer. The circular dichroism spectra were recorded on a JASCO J-720 W spectropolarimeter at room temperature. The simultaneous CD and LD measurements were conducted for R-1 and S-1 using the multi-probe function in the J-1500 CD spectrometer. Each sample was diluted by KCl with a ratio of 1/50 and pressed into a pellet.