Effect of the Substituents on the Ligand of Iron Phthalocyanines Adsorbed on Graphite Electrodes on Their Activity for the Electrooxidation of 2-Mercaptoethanol

Metallophthalocyanine-based molecular materials as catalysts for electrochemical reactions

“…This clearly shows that cobalt phthalocyanine layer not only acts as a catalyst towards the oxidation of 2-ME but also for the reduction of the corresponding disulfide. This has also been observed for the oxidation of 2-ME on Fe phthalocyanines and the more active the catalysts, the smaller the separation between the 2ME oxidation peak and the disulfide reduction peak [290]. The catalytic activity of MPcs for the oxidation of thiols is strongly dependent on the nature of the metal in the macrocycle [14,21,321].…”

“…Metallophthalocyanines and related complexes exhibit catalytic activity for the electrochemical oxidation of a great variety of thiols [14,21,100,274,[284][285][286][287][290][291][292][321][322][323][324][325][326][327][328][329][330][331][332][333][334][335][336][337][338] and for the reduction of the corresponding disulfides [100]. These "molecular phthalocyanine electrodes" act by lowering the overpotential of oxidation or reduction of the target molecules [14].…”

“…In earlier studies of the electrocatalytic activity of MPcs for the oxidation of thiols such as 2-ME and 2-aminoethanethiol [290,333,334,[338][339][340] the catalytic activity (measured as current at constant potential) followed a linear correlation with the redox potential (driving force) of the complex, when immobilized on graphite electrodes. The activity increases as the M(II)/M(I) formal potential of the catalyst becomes more negative, that is to say, the activity increases when the driving force of the catalyst decreases.…”

Non-enzymatic glucose biosensor based on overoxidized polypyrrole nanofiber electrode modified with cobalt(II) phthalocyanine tetrasulfonate

“…It is known that the adsorbed macrocyclic complexes exhibit a well-defined reversible voltammetric peaks that appear in the range −0.8 and −0.2 V. These faradaic processes can be assigned to the Co(II)/Co(I) reversible redox couple (Lever, 1993;Aguirre et al, 2002;Gulppi et al, 2005). As expected, the formal redox potential of the Co(II)/Co(I) couple shifts to more positive potentials by the effect of electron-withdrawing groups on CoPcTS complex since they decrease the electron density on the metal center and make its oxidation more the difficult compared to the H-substituted CoPc.…”

Reactivity trends of Fe phthalocyanines confined on graphite electrodes in terms of donor–acceptor intermolecular hardness: Linear versus volcano correlations

“…In previous studies, the relationship between the catalytic activity with structural and thermodynamic parameters of the phthalocyanines has been established [15,[20][21][22][23][24][25][26][27]. These parameters include the formal potential of the M(II)/(I) redox couple in the metal complex [11,21], the role of the substituents in the ligand system [15,20], the magnetic moment [28], and the catalytic activity in other processes [11,[15][16][17][18][19][20][21][28][29][30][31][32][33][34][35][36][37]. This type of correlations shows that the redox potential of the catalysts needs to have an intermediate value to achieve maximum activity, and somehow resembles the Sabatier principle.…”