Redox potentials porphyrazines

Electrochemistry-EPR. The redox potentials of the porphyrazines, 69a, 69b, 70a, and 70b were measured using cyclic voltammetry (Table XX). The redox potentials of the molybdocene appended porphyrazines 70a and 70b showed marked changes from that observed for the parent ligands 69a or 69b suggesting that the peripheral metalation by molybdocene profoundly alters the physiochemical properties of the macrocycle by more than just the sum of the two parts (6). 

Electrochemistry. The redox potentials, as measured by cyclic voltammetry, of 76 (trans) and 77 (cis) porphyrazines are given in Table XXII, where they are compared to all other isomeric products (A4, B4, A3B, AB3). These redox processes show no obvious correlations between the amount of thioether functionality and redox potential. 

Cyclic voltammetry was carried out in the presence of penta- and hexacyano-ferrate complexes in order to probe the homogeneity and conductivity of the TRPyPz/CuTSPc films (125), (Fig. 36). When the potentials are scanned from 0.40 to 1.2 V in the presence of [Fe (CN)6] and [Fe CN)5(NH3)] complexes, no electrochemical response was observed at their normal redox potentials (i.e., 0.42 and 0.33 V), respectively. However, a rather sharp and intense anodic peak appears at the onset of the broad oxidation wave, 0.70 V. The current intensity of this electrochemical process is proportional to the square root of the scan rate, as expected for a diffusion-controlled oxidation reaction at the modified electrode surface. The results are consistent with an electrochemical process mediated by the porphyrazine film, which act as a physical barrier for the approach of the cyanoferrate complexes from the glassy carbon electrode surface. 

Electrochemistry. The redox processes for porphyrazines 21, 25, 28, 29, the heteroleptic Zr (pz/porphyrin) 30 and 31 have been measured by cyclic voltammetry and the formal potentials are given in Table VII. The potentials are compared to the available data for the analogous porphyrin and pc complexes. In general, the electrochemical behavior of the pz sandwiches more closely mirror that observed for the phthalocyanines than the porphyrins. In particular, all of the porphyrazines have at least one ring-based oxidation, attributable to the formation of the bis Jt-radical cation for Lu(III) sandwiches and the formation of the 7T-radical cation for the Zr(IV) and Ce(IV) sandwiches. Additionally, all of the porphyrazines exhibit at least one ring-based reduction. 

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