Resumen

GUSHIKEM, Yoshitaka  y  CAMPOS, Elvio A.. Cobalt(II) Hematoporphyrin IX immobilized in a cellulose acetate niobium(V) oxide composite membrane: preparation and oxygen reduction study. J. Braz. Chem. Soc. [online]. 1998, vol.9, n.3, pp. 273-278. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50531998000300011.

Hematoporphyrin IX [8,13,-bis(1-hydroxyethyl)-3,7,12,17-tetramethyl-21H-porphyrin-2,18-dipropionic acid] was adsorbed on the organic-inorganic composite membrane Cel/Nb₂O₅ surface. The porphyrin is strongly adhered on the Nb₂O₅ surface by reaction of the porphyrin CO₂H groups with Nb₂O₅ forming the -COO-Nb chemical bond. Metallation of the porphyrine ring was made very easily by immersing the membrane in Co(II) solution and allowing to rest for a few hours. The electronic absorption bands due to the Q bands indicated the symmetry change from D_2h to D_4h upon metallation of the porphyrin ring. The chemical analyses of the material confirmed that the metallation yield was practically 100%. Oxygen was reduced on a electrode surface made with the material under a cathodic peak potential of -390 mV, in 1 M KCl solution at pH 1, temperature of 298 K and at ambient pressure. The oxygen reduction was proposed to occur by a two electron transfer mechanism. A linear cathodic peak current response was obtained for dissolved oxygen concentrations between 1.5 and 15 ppm.

Palabras llave : Co(II) hematoporphyrin IX; celullose acetate membrane; cellulose-niobium(V) oxide composite membrane; oxygen catalytic reduction.