The role of hydrogen bond formation in the extracting efficiency of NADES formulations

The simplicity and versatility of natural deep eutectic solvents (NADES), together with a wide range of potential applications, make them great candidates to fight the lack of sustainability and circularity in large-scale industrial chemistry. Among the most prominent applications of NADES, extraction of phenolic compounds (PC) from natural sources remains one of the most attractive ones, due to the high commercial value of both, solvent and solute. In the present study, an in-depth analysis of the underlying mechanisms of extraction in NADES-PC systems is performed via quantification of the spin-spin interactions using 2D NMR experiments. The structure of the hydrogen bond donor, acceptor-to-donor molecular ratio, or number and distribution of the hydroxyl groups are determined as key components governing the solubility of PC in NADES. Moreover, our results reveal how studying the solvent hydrogen bond network formation between the NADES acceptor and donors can be easily translatable into understanding the solvation patterns and predicting the solubility efficiency of PC at low concentrations, below the level of direct detection.