Photoelectroanalytical chemistry: electrochemical detection of a photochemically active species, tris(2,2'-bipyridine)ruthenium(II).

Abstract

The suitability of the molecule tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)/sub 3//sup 2 +/) for use as the basis for a derivatizing or labelling reagent is under consideration. Four Co(III) complexes were tested for use as electron-transfer quenchers. The most analytically useful of the four is tris(glycinato)cobalt. With this quencher, the photooxidation/electrode reduction cycle of Ru(bpy)/sub 3//sup 2 +/ was studied. Experimental dependences of photocurrent on light intensity, quencher concentration, and Ru(bpy)/sub 3//sup 2 +/ concentration are similar to, but not exactly, that predicted for a simple photosensitive CE (regenerative) or catalytic mechanism. Studies of the flow rate dependence of the photocurrent demonstrated an apparent increase in the effective rate constant for the photooxidation of Ru(bpy)/sub 3//sup 2 +/ as the concentration of Ru(bpy)/sub 3//sup 2 +/ decreased. An electron transfer mediator, Ru(CN)/sub 6//sup 4 -/, was used to minimize the influence of side reactions of Ru(bpy)/sub 3//sup 3 +/.