Abstract
We prepared the mixed monolayer-modified Au electrode composed of negatively charged CoIII complex (1) and hydroxyl-terminated alkanethiols (Cn; n = 2, 6), 1/Cn-Au, using the ‘step-by-step’ immobilization method; the low-density monolayer of 1 (1-Au) was firstly constructed with a spacing and then Cn molecules were filled in the gap of 1. In the cyclic voltammetric measurement of horse heart cytochrome c (cyt c) using 1/C2-Au, only a pair of oxidation-reduction wave was observed with almost the same peak separation as the case of 1-Au. Since the electron transfer rate by using the single monolayer of C2 was much faster than that of 1-Au, it clearly indicates that the modification of C2 does not cause the phase-separation and C2 molecules on Au do not influence to the electron transfer reaction with cyt c. In contrast, 1/C6-Au showed faster electron transfer rate than the cases of 1-Au and 1/C2-Au, but exhibited slower rate than that of single monolayer of C6. These findings indicate that cyt c firstly interacts with negatively charged 1, and then electron transfer reaction proceeds via C6 molecules on Au electrode.
