Cobalt porphyrins electrochemical detection with

B. Electrochemical Detection of Azanone with a Cobalt Porphyrin 131... 

Irradiation of iron and cobalt porphyrins (13 Fe(TPP), 14 Co(TPP), H2TPP = 5,10,15,20-tetraphenyl-21/f,23/f-porphyrin) in the presence of triethylamine (TEA) using > 320-nm tight caused the photocatalytic reduction of CO2 [15, 16, 27-31]. When 13 was used as a photocatalyst, CO was detected with TNco = 70 after 180-h irradiation [15]. Formic acid was the main product when 14 was employed as a photocatalyst [16]. The reaction mechanism proposed on the basis of UV-vis absorption changes during photolysis and radiolysis, and electrochemical measurements are shown in Scheme 3. M (TPP) is reduced to M (TPP) by photoinduced electron transfer from TEA, which subsequently disproportionates to M°(TPP), the proposed catalyticaUy-active species. 

Modification of the electrode started with academic studies on physical and chemical adsorption, i.e., with the appearance of fundamental researches on adsorption of different species on electrode surfaces, both under polarization and at open circuit potential [3]. The properties of similar chemically modified electrodes , in which the modifier consists of a monolayer of a variety of chemical species with different characteristics, possessing (or not) particular properties, were initially studied in a purely electrochemical context, aimed at the collection of fundamental physico-chemical data. A small group of electrochemists were among those involved in these basic studies, envisioning the perspectives opened by the novel systems. In the first, really fascinating, work with similar monomolecular layers, cobalt porphyrin and phthalocyanine, as well as deliberately synthesized dicobalt face-to-face porphyrins were adsorbed on Pt or C surfaces to catalyze molecular oxygen reduction [4]. However, similar systems were not always used or adequately tested in proper amperometric sensing by researchers more interested in electroanalysis dicobalt face-to-face porphirins still constitute a rare example of tailored materials for selective amperometric detection. 

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