Electrochemical Evidence for the Affinity of n‐Alkyl Sulfonate Group‐Modified Viologens to Gold

The cyclic voltammograms of n ‐alkyl sulfonate‐group modified viologens on glassy carbon and platinum electrodes are similar to those of dimethyl and di‐ n ‐heptyl viologen; on gold electrodes, however, the new species demonstrate a new surface wave whose size depends on the concentration of the n ‐alkyl sulfonate group‐modified viologen in the electrolyte. The saturation coverage is calculated at 7.3 × 10 − 10 and at 9.4 × 10 − 10 mol cm − 2 for N ‐methyl‐ N ′ ‐(3‐sulfonato‐ n ‐propyl)‐4,4′‐bipyridinium iodide (I) and for N ‐( n ‐heptyl)‐ N ′ ‐(3‐sulfonato‐ n propyl)‐4,4′‐bipyridinium iodide (II), respectively, suggesting formation of a monolayer with the viologen moieties configured normal to the gold electrode surface.