Tetrasulfonated phthalocyanines

Coutanceau C, El Hourch A, Crouigneau P, Leger JM, Lamy C. 1995. Conducting polymer electrodes modified by metal tetrasulfonated phthalocyanines Preparation and electro-catalytic behaviour towards dioxygen reduction in acid medium. Electrochim Acta 40 2739-2748. 

Coordination of NO to the divalent tetrasulfonated phthalocyanine complex [Co(TSPc)]4 results in a complex formally represented as [(NO )Coin(TSPc)]4 kf= 142M-1s-1, KA 3.0 x 105 M-1). When adsorbed to a glassy carbon electrode, [Co(TSPc)]4- catalyzes the oxidation and reduction of NO with catalytic currents detectable even at nanomolar concentrations. Electrochemistry of the same complex in surfactant films has also been studied.905 Bent nitrosyl complexes of the paramagnetic trivalent tropocoronand complex Co(NO)(TC) ((189), R = NO) have also been reported.849... 

Manganese(II)-A/, A/r -dipyridoxylethylenediamine-A/r, AT-diacetate 5,5 -bis(phosphate) 75 (DPDP) is clinically used for enhancing contrast in the liver (detection of hepatocellular carcinomas) (312). Some dissociation of Mn(II) appears to occur in the liver, and enhancement can also be obtained in functional adrenal tissues (313). Manganese(II)-tetrasulfonated phthalocyanine also shows tumor localization properties and is a more efficient relaxation agent than the analogous Gd(III) complexes (314). 

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). 

The binuclear complexes H20(Pc)Cr0Cr(Pc)H20 and NH3(Pc)CrOHCr(Pc)OH form when [Cr2O(NH3)10]Cl4-H2O and [Cr2(OH)(NH3)i0]Cl5, respectively, are allowed to react with phthalonitrile at 543 °C.1295 The 4, 4, 4 ,4""-tetrasulfonated phthalocyanine (TSPc) complex, OH(TSPc)CrOHCr(TSPc)H20 was obtained by fusing [Cr2OH(NH3)i0]Cl5 with ammonium-4-sulfophthalate and urea.1295... 

Castellani, A. M. Goncalves, J. E. Gushikem, Y. The use of carbon paste electrodes modified with cobalt tetrasulfonated phthalocyanine adsorbed in silica/titania for the reduction of oxygen. Journal of New Materials for Electrochemical Systems (2002) 5(3) 169-172. 

Transition Metal Phthalocyanines Water-soluble tetrasulfonated phthalocyanines incorporating transition metals of the first row, particularly, FeTsPc and CoTsPc, may be regarded as among the first adsorbed macrocycles for which the reaction mechanisms for oxygen reduction in aqueous electrolytes have been studied in depth using RDE and RRDE techniques [60, 90]. 

Figure 4.4 Structural formulae (zinc complexes) of (a) tetrasulfonated phthalocyanine (TSPc different isomers present) and (b) tetrasulfonated tetraphenylporphyrin (TSTPP).

The interplay of different dye molecules present during the electrodeposition reactions of dye-modified ZnO was studied for zinc complexes of tetrasulfonated phthalocyanine (TSPcZn, Figure 4.4a) and tetraphenylporphyrin (TSTPPZn) in which case both dyes (Figure 4.4b) were simultaneously adsorbed to form a hybrid material with ZnO [258]. The typical absorption bands for both dyes were detected. Films of TSPcZn/ZnO consisted of larger particulate domains when compared with TSTPPZn/ZnO or (TSTPPZn + TSPcZn)/ZnO. The presence of the porphyrin stabilized the phthalocyanine on the ZnO since a greater amount of TSPcZn was adsorbed. In the photosensitization of ZnO, TSPcZn and TSTPPZn worked... 

Spectroscopic and electrochemical studies of transition metal tetrasulfonated phthalocyanines ... 

V. Voltammetric studies of adsorbed tetrasulfonated phthalocyanines (MTsPc) in aqueous solutions. 

Figure 2.13. Volcano plot for the electrocatalytic activity of different M-tetrasulfonated phthalocyanines adsorbed on graphite for O2 reduction in 0.1-M NaOH, as a function of the number of d-electrons in the metal. From ref. [6], reproduced with permission of Elsevier.

Zecevic, S., B. Simic-Glavaski, E. Yeager, A.B.P. Lever, and PC. Minor (1985). Spectroscopic and electrochemical studies of transition metal tetrasulfonated phthalocyanines Part V. Voltammetric studies of adsorbed tetrasulfonated phthalocyanines (MTsPc) in aqueous solutions. J. Electroanal. Chem. 196, 339-358. 

Zilbermann, I., J. Hayon, T. Katchalski, R. Ydgar, J. Rishpon, A.I. Shames, E. Korin, and A. Bettelheim (2000). Spectroscopic and electrochemical characterization of the interaction of nitrogen monoxide and cobalt tetrasulfonated phthalocyanine in aqueous solutions and surfactant films. Inorg. Chim. Acta, 305, 53-60. 

Since pyrrole and its derivatives form very stable conducting surfaces, Za-gal, Bedioui, and coworkers used ultramicro-carbon-fiber electrode modified with polypyrrole-dopped cobalt-tetrasulfonated phthalocyanine for the electrocatalytic oxidation of 2-ME The resulting electrode was stable and showed a detection limit of 8 10 M. Pyrolle substituted phthalocyanines have been used for the analysis of cysteine. Electrocatalytic behavior of MPc complexes has also been examined under homogeneous conditions. Water soluble OMo (OH)TSPc catalyzed the oxidation of cysteine under homogeneous conditions. ... 

Parez, E.F., L.T. Kubota, A.A. Tanaka, and G. De Oliveira Neto (1998). Anodic oxidation of cysteine catalysed by nickel tetrasulfonated phthalocyanine immorbiUzed on silica gel modified with titanium(lV) oxide. Electrochim. Acta 43(12-13), 1665-1673. 

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