Characteristics of monolayers of ferrocene derivatives and estimation of electrical double layers formed in Langmuir films

In order to estimate the potential difference of the electrical double layer formed in heterogeneous Sensitizer (S)/Electron Donor (D) Langmuir–Blodgett (LB) films, the surface potentials of the constituent monolayers were measured simultaneously with the π–A isotherms. The S monolayer was a mixed [Ru(bpy)3]2+ complex monolayer with a long alkyl fatty acid, while the D monolayer was one of three kinds of ferrocene monolayers with different signs of the hydrophilic head groups and with the same redox potential. The formation of the potential difference between the charged head group of the amphiphile and its counterion at the water-air interface was confirmed; those values were consistent with the electrical double-layer effect on the luminescent lifetime of [Ru(bpy)3]2+ in the S monolayer in contact with the D monolayer.