2D-IR spectroscopy of carbohydrates: Characterization of thiocyanate-labeled β-glucose in CHCl₃ and H₂O.

This article focuses on the application of site-specific vibrational reporter groups, specifically the thiocyanate (SCN) label, to carbohydrates for the first time using two-dimensional infrared (2D-IR) spectroscopy. The study presents a synthesis strategy to incorporate SCN at the C2 position of β-glucose, including a method to remove benzyl-protecting groups to enable aqueous solubility and native-like conditions. Experimental results demonstrate that SCN-labeled β-glucose exhibits vibrational lifetimes and spectral diffusion dynamics comparable to methyl-thiocyanate (MeSCN), a known vibrational probe, validating SCN as an effective reporter in carbohydrates. The findings reveal spectral inhomogeneities likely due to multiple conformers or subensembles of glucose, and suggest that this labeling approach can facilitate future biophysical studies of carbohydrate interactions, such as protein–ligand binding, on ultrafast timescales previously inaccessible in glycoscience.