Tris(2,2′‐bipyridyl‐5‐sulfonic acid)rhodium(III), an Improved Redox Catalyst for the Light‐Induced and the Electrochemically Initiated Enzymatic Reduction of Carbonyl Compounds

Abstract

Unchanged activity after 36 hours is displayed by the light‐induced redox system consisting of nitrilotriethanol, NAD⊕, horse liver alcohol dehydrogenase, cyclohexanone, and [Ru(bpy)3]2⊕, with the title compound [Rh(L3)]3⊕ as electron relay. The electrochemically initiated enzymatic reduction of cyclohexanone in an analogous system also takes place with [Rh(L3)]3⊕ as redox catalyst without the formation of inactive (NAD)2. Since the reduced form of [Rh(L3)]3⊕ does not reduce carbonyl compounds, it is also possible to exploit fully the stereospecificity of the enzyme with the system described here.