Reinterpreting the role of the catalyst formal potential. the case of thiocyanate electrooxidation catalyzed by CoN4-l

C. Linares-Flores, D. Mac-Leod Carey, A. Muñoz-Castro, J. H. Zagal, J. Pavez, D. Pino-Riffo, R. Arratia-Pérez

Research output: Contribution to journalReview articlepeer-review

11 Citations (Scopus)

Abstract

We report on the interaction of the thiocyanate ion (SCN -) with Co macrocyclics. In order to modulate the electron density located on the metal center, we used several phthalocyanine and macrocyclic molecules with electron-donating or electron-withdrawing groups located on the phthalocyanine ligand. We studied the following substituted Cobalt-macrocycles (CoPcâ's): cobalt-tetraamino-phthalocyanine (4β(NH 2)CoPc), cobalt-phthalocyanine (CoPc), cobalt-octahydroxyethylthio-phthalocyanine (8β(SC 2H 4OH)CoPc), cobalt-tetrapentylopyrrol- phthalocyanine (4β(PenPyr)CoPc), cobalt-tetrapyridino-phorphyrazine (4β(Pyr)CoPc), cobalt-octaethylhexyloxy-phthalocyanine (8β(EH)CoPc), cobalt-octamethoxyphthalocyanine (8β(OCH 3)CoPc), and cobalt-hexadecafluorophthalocyanine (16(F)CoPc). Our results for the formation of a CoPc-SCN adduct indicate that the electron-withdrawing groups favors the formation of an adduct between thiocyanate and the Co center, with an increase of the thiocyanate-binding energy. When the adducts are formed, they exhibit an increasing chemical potential, thus indicating the feasibility to produce the catalysis once the adducts are formed. The molecular hardness values suggest that the CoPc's with electron-withdrawing substituents will show low catalytic activity while those with electron-donor substituents will show an enhanced catalytic activity. The functionalized Co-phthalocyanine shows the highest catalytic activity for the thiocyanate electroxidation, which presents an appropriate energy gap (HOMOSCN --LUMO CoPc's) for the adduct formation and the subsequent electronic transfer.

Original languageEnglish
Pages (from-to)7091-7098
Number of pages8
JournalJournal of Physical Chemistry C
Volume116
Issue number12
DOIs
Publication statusPublished - 29 Mar 2012

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

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