Synthesis, solvent interactions and computational study of monocarbohydrazones

Carbohydrazones are compounds that are increasingly studied due to their wide potential biological activity. Monocarbohydrazones (mCHs), as one of the carbohydrazone derivatives, so far have been poorly investigated. For a more detailed study, in this paper, eighteen compounds of monocarbohydrazones (eight known and ten newly synthesized derivatives) were synthesized and characterized using NMR and IR spectroscopy. As carbohydrazones show E/Z isomerization caused by the presence of the imino group, some of the synthesized mCHs are in the form of a mixture of these two isomers. The effects of specific and nonspecific solvent-solute interactions on the UV absorption maxima shifts were evaluated using linear free energy relationships principles, i.e., using Kamlet-Taft's and Catalan's models. For more information about interactions between dissolved substance and the surrounding medium, correlations have been made with Hansen's solubility parameters. The influence of the structure on the spectral behavior of the compounds tested was interpreted using Hammett's equation. Experimentally obtained physicochemical properties of mCHs were compared to and confirmed with computational methods that included TD-DFT calculations and MP2 geometry optimizations. Graphic abstract