FTIR was performed on each sample by depositing ∼2 mg of MP powder onto the window of Nicolet iS5 FT-IR Spectrometer equipped with a Thermo Scientific iD5 single-bounce attenuated total reflectance (ATR) accessory featuring a diamond crystal with a ZnSe lens. Spectral data were collected over a range of 4000 cm -1 to 500 cm -1 and were processed (baseline correction and smoothing) using MestreNova.