Premium
Zinc Porphyrin Metal‐Center Exchange at the Solid–Liquid Interface
Author(s) -
Franke Matthias,
Marchini Florencia,
Jux Norbert,
Steinrück HansPeter,
Lytken Ole,
Williams Federico J.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201600634
Subject(s) - porphyrin , ion exchange , chemistry , zinc , adsorption , aqueous solution , copper , metal , monolayer , inorganic chemistry , tetraphenylporphyrin , ion , metal ions in aqueous solution , photochemistry , organic chemistry , biochemistry
Demetalation of zinc 5,10,15,20‐tetraphenylporphyrin (ZnTPP) under acidic conditions and ion exchange with Cu 2+ ions at neutral pH are both rapid reactions in the liquid medium. However, for ZnTPP monolayers adsorbed on a Au(111) surface exposed to aqueous solution, we find that, although ion exchange takes place rapidly as expected, demetalation does not occur, even at pH values as low as 0. Based on this, we conclude that metal center exchange on the surface does not proceed through a free‐base porphyrin as an intermediate. Furthermore, once formed, CuTPP is stable on the surface and the reverse exchange from CuTPP to ZnTPP in the presence of Zn 2+ ions could not be achieved. The preference for copper is so strong that even an attempt to exchange adsorbed ZnTPP with Ni 2+ ions in the presence of traces of Cu 2+ yielded CuTPP rather than NiTPP.