Thermodynamic characteristics as well as peculiarities of hydrogen bonding in aqueous solutions of new deep eutectic solvents (DES) based on synthetic carboxybetaine have been studied. Cheap starting reagents (acrylic acid and 2-dimethylaminoethanol), simple preparation, and high yields are the advantages of the proposed betaine. Analyses of the calculated stabilization energies and natural bond orbital delocalization energies revealed the absence of preferential association in aqueous reline solutions tested for the comparative purpose. On the other hand, it was demonstrated that water preferentially associates with betaine molecules as this type of interaction was proved to possess the highest stabilization energy among the considered complexes. These data were used to discuss the anomalous behavior of the experimentally determined enthalpy and entropy factor of a viscous flow. Thus, sharp increase in the values of TΔ S and Δ H was demonstrated for the betaine-based solutions with 30-40 wt % water. The observed thermodynamic peculiarities were explained in terms of structurization of the betaine-based DES caused by strong H-bonding between betaine and water molecules and were supported with experimental IR spectroscopy measurements.

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The unusual interactions in organic liquids such as methane derivatives, arenes, and alkanes by the infrared (IR) method were revealed. The transformations of molecular shapes, arising from nonclassical hydrogen and dihydrogen bonds, as well as water factor provide the existence of supramolecular structures in organic fluids. The interpretation of the obtained results in terms of the quantum-chemical calculations has been suggested.