Iron tetrasulfonated phthalocyanine

We can now make sensible guesses as to the order of rate constant for water replacement from coordination complexes of the metals tabulated. (With the formation of fused rings these relationships may no longer apply. Consider, for example, the slow reactions of metal ions with porphyrine derivatives (20) or with tetrasulfonated phthalocyanine, where the rate determining step in the incorporation of metal ion is the dissociation of the pyrrole N-H bond (164).) The reason for many earlier (mostly qualitative) observations on the behavior of complex ions can now be understood. The relative reaction rates of cations with the anion of thenoyltrifluoroacetone (113) and metal-aqua water exchange data from NMR studies (69) are much as expected. The rapid exchange of CN " with Hg(CN)4 2 or Zn(CN)4-2 or the very slow Hg(CN)+, Hg+2 isotopic exchange can be understood, when the dissociative rate constants are estimated. Reactions of the type M+a + L b = ML+(a "b) can be justifiably assumed rapid in the proposed mechanisms for the redox reactions of iron(III) with iodide (47) or thiosulfate (93) ions or when copper(II) reacts with cyanide ions (9). Finally relations between kinetic and thermodynamic parameters are shown by a variety of complex ions since the dissociation rate constant dominates the thermodynamic stability constant of the complex (127). A recently observed linear relation between the rate constant for dissociation of nickel complexes with a variety of pyridine bases and the acidity constant of the base arises from the constancy of the formation rate constant for these complexes (87). 

Even fewer detailed studies of the reaction of O2 with iron (II) complexes appear to have been made. The rates range from the very slow [oxidation of Feaq in acid perchlorate (i3)] to the rapid [interaction with oxygen of, e.g., the Fe(II) complex of cysteine (14) ]. Once again the incorporation of O2 in the coordination sphere of the metal appears likely from considerations of the rate law (13, 14) as well as in certain cases from the nature of the product. The reversible interaction of O2 with the iron (II) phthalocyanine tetrasulfonate complex has been observed both in solution (15) and in the solid state (16) but no kinetic studies have been reported. 

Duarte J, Luz R, Damos F, Tanaka AA, Kubota LT (2008) A highly sensitive amperranetric sensor for oxygen based on iron(ll) tetrasulfonated phthalocyanine and iron(in) tetra-(N-methyl-pyridyl)-porphyrin multilayers. Anal Chim Acta 612(1) 29—36... 

Figure 35. Model proposed by Nikolic, Adzic and Yeager for adsorbed iron and cobalt tetrasulfonated phthalocyanines on the basal plane of stress annealed pyrolytic graphite, a, View parallel to the surface b, view perpendicular to the surface.

Other examples of important biomolecules that can be detected using carbon paste electrodes modified with phthalocyanines are the neimotransmitters dopamine, serotonin, and epinephrine. Oni et al. [37] described the utilization of CPE containing iron(II) phthalocyanine (PePc), and iron(II) tetrasulfonated phthalocyanine ([FeTSPc]" ]) for the detection of dopamine and serotonin. The presence of ascorbic acid did not interfere with the determination of both species, individually or in a mixture. Shahrokhian et al. [38] performed epinephrine determinations in pharmaceutical and clinical samples through voltammetric techniques with high sensitivity and selectivity, low detection limit (sub-micromolar), and high reproducibility. 

Transition metal compounds, such as organic macrocycles, are known to be good electrocatalysts for oxygen reduction. Furthermore, they are inactive for alcohol oxidation. Different phthalocyanines and porphyrins of iron and cobalt were thus dispersed in an electron-conducting polymer (polyaniline, polypyrrole) acting as a conducting matrix, either in the form of a tetrasulfonated counter anion or linked to... 

Figure /. 3-D absorbance spectra of a polypyrrole film electroformed at a gold electrode at a constant potential (0.3 V/MSE) in 0.5 M H2SO4 + 0.1 M pyrrole (a) without and (b) with incorporation of tetrasulfonated iron phthalocyanine.

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