Voltammetric Study of the Complexation of Propafenone Hydrochloride (Rythmol SR) with Co2+, Ni2+, Zn2+, and Mn2+ Ions

Square-wave (SW) voltammetric investigation of the binding processes of propafenone hydrochloride (PFOH) with Co2+, Ni2+, Zn2+, and Mn2+ ions was carried out at pH of 7.4. For the formed complexes, both average stoichiometries and stability constants were found by means of modified De Ford–Hume method. According to SW voltammetric data, the metal : ligand ratio of 1 : 2 for Mn2+ was obtained. Moreover, PFOH formed complexes in average metal : ligand ratio of 1 : 2 for Ni2+ and Zn2+; however, this average ratio was 1 : 6 for the Co2+ complex in the solution phase. The order of their stability constants was observed to obey Co(PFOH)6 ≫ Ni(PFOH)2 > Zn(PFOH)2 > Mn(PFOH)2. Also, the ligand numbers and formation constants of the successively formed Co(PFOH)j, Ni(PFOH)j, and Zn(PFOH)j complexes in solution phase were calculated.