Hydrogen bond interactions of dopamine hydrochloride with urea

The interactions of dopamine hydrochloride (DH) with urea were investigated by electrochemical cyclic voltammetry, density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) analysis. Changes of the oxidation/reduction peak potentials of DH in DH-urea-H2O systems indicated that the hydrogen bonds were formed between DH and urea. The DFT and QTAIM results confirmed that the hydrogen and oxygen atoms on phenolic hydroxyl groups, the hydrogen atoms on NH3+ and the aromatic ring of DH can form hydrogen bond with the oxygen and hydrogen atoms of urea. Moreover, the solution pH has an effect on the electrochemical behaviour of DH in the system.