*4.4. Fourier Transform Infrared Spectroscopy—FT-IR*

The Fourier transform infrared spectrum (FT-IR) of HSD was obtained on a Cary 630 FT-IR spectrometer equipped with a monolithic diamond attenuated total reflection (ATR) accessory (Agilent Technologies Inc., Santa Clara, CA, USA). The spectra were recorded accumulating 128 scans at a resolution of 4 cm<sup>−</sup><sup>1</sup> in the range from 4000 to 400 cm<sup>−</sup>1.
