Theoretical investigation on hydrogen bond interaction between adrenaline and hydrogen sulfide.

In this study, we elucidated the formation of hydrogen bond between adrenaline (AD) and hydrogen sulfide utilizing computational studies. Six potential complexes were studied including geometrical parameters, energy, vibrational frequency, topological analysis, natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM), and NMR analysis. Moreover, these calculations were examined through DFT/ωB97XD/6-311G++(d,p) level. It was found that there are no indication on formation on hydrogen bonding between the two catecholic OHs where the one formed between the amino group and the hydroxyl oxygen atom of adrenaline monomer was broken in AS to form two new interactions namely SHN and OHS, while it retained in other complexes. Furthermore, the bond became stronger due to cooperativity in AS and AS, for the presence of withdrawing effect of the phenyl ring, the H-bonds formed with the side chain oxygen atom. The adrenaline and HS interaction was experimentally examined via FT-IR spectrometry and thin layer chromatography for confirmation of our theoretical study. Graphical abstract.