World Scientific
Skip main navigation

Cookies Notification

We use cookies on this site to enhance your user experience. By continuing to browse the site, you consent to the use of our cookies. Learn More
×

System Upgrade on Tue, May 28th, 2024 at 2am (EDT)

Existing users will be able to log into the site and access content. However, E-commerce and registration of new users may not be available for up to 12 hours.
For online purchase, please visit us again. Contact us at customercare@wspc.com for any enquiries.

Cobalt porphyrins immobilized on niobium(V) oxide grafted on a silica gel surface: study of the catalytic reduction of dissolved dioxygen

    https://doi.org/10.1002/jpp.360Cited by:26 (Source: Crossref)

    Hematoporphyrin IX, H2HMP, 8,13-bis(1-hydroxyethyl)-3,7,12,17-tetramethyl-21H,23H-porphine-2,18-dipropionic acid and protoporphyrin IX, H2PP, 8,13-divinyl-3,7,12,17-tetramethyl-21H,23H-porphine-2,18-dipropionic acid were efficiently immobilized on niobium oxide grafted on a silica gel surface, SiO2/Nb2O5, by the -COONb bond formed between the porphyrin carboxyl groups and the grafted Nb2O5. These immobilized porphyrins, SiO2/Nb2O5/H2HMP and SiO2/Nb2O5/H2PP, were further reacted with Co(II) in dimethylformamide, resulting in SiO2/Nb2O5/CoHMP and SiO2/Nb2O5/CoPP metallated complexes. The UV-vis spectra of the solid materials showed changes of the Q-bands (a2ueg transition) upon metallation, indicating that by incorporation of Co(II) in the porphyrin ring the local symmetry changed from D2h to D4h. These materials, when incorporated in carbon paste electrodes, presented the property of electrocatalyzing O2 reduction. Rotating disk experiments were performed in order to estimate the number of electrons involved in the process. It was observed that, for both modified electrodes, O2 was reduced to water in a four-electron process. Amperometric studies showed the potentiality of both modified electrodes as sensors for the determination of dissolved dioxygen. The response time was less than 3 s. A linear response for both systems was obtained between 2 and 12 ppm.

    Most comprehensive & up-to-date research on PORPHYRINS
    Handbook of Porphyrin Science now available in 46 volumes