The electrochemistry and thin-layer luminescence spectroelectrochemistry of rhodamine 6G at a 4,4'-bipyridine-modified gold electrode

摘要

We report on the first direct electrochemistry and fluorescence spectroelectrochemistry of rhodamine 6G at a 4.4'-bipyridine-modified gold electrode. The value of n determined in spectropotentiostatic experiments at 1.87 x 10 6mol 1- of rhodanune 6G in 0.20 mol~(-1) KCI solution is 1.15. and the experimental value obtained for Er” is -0.787 V versus Ag AgCI KCl_(sat,). which agrees very well with the value (E~(0')=-0.791 V) obtained using cyclic voltammetry at .a modified gold electrode. The values of the diffusion coefficients D0 and DR for the oxidized and reduced forms of rhodamine 6G calculated from results of potential step and in situ fluorescence measurement experiments are 4.0 x 10 ~(-6)cm~2 s~(-1)-and 4.2 x 10~(-6)cm~2 s~(-1), respectively. Cyclic voltam-mograms of rhodamine 6G show that the peak current I_pis proportional to the square root of the potential scan rate #upsilon#~(1/2) the ratio of the reduction to the oxidation peak height is about unity, and the separation of both reduction and reoxidation peak potentials #DELTA#E_p is essentially constant at 135 mV at low scan rates. These results indicate that electrochemistry of rhodarnine 6G at a 4,4’-bipyridine-modified gold electrode is a quasi-reversible one-electron electrode process.