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A Pentaporphyrin as a Switching Device Activated by Proton and Redox Stimuli
Author(s) -
Ceroni Paola,
Bergamini Giacomo,
Aubert Nicolas,
Troiani Vincent,
Solladié Nathalie
Publication year - 2005
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200500173
Subject(s) - porphyrin , protonation , redox , photochemistry , free base , chemistry , electrochemistry , quenching (fluorescence) , proton , electrode , fluorescence , inorganic chemistry , organic chemistry , ion , salt (chemistry) , physics , quantum mechanics
A new pentaporphyrin array, constituted by a peptidic backbone and lateral chains with two free‐base, one Mg II , and two Zn II porphyrins, has been synthesized. The electrochemical and photophysical properties are not the mere superposition of those of its model compounds: slight shifts of the E 1/2 values and strong perturbation of both the Soret and Q‐band absorption show substantial ground‐state interactions among the component units, which take advantage of the rather flexible nature of the peptidic links. This multiporphyrin array, despite the flexible and nonconjugated nature of the peptidic spacers, plays the role of an antenna for visible light: an efficient photoinduced energy transfer takes place from the metalated porphyrin units to the free‐base ones. Furthermore, the light emitted by the antenna can be: 1) tuned upon protonation of the free‐base units, or 2) turned off by a redox input, since the formation of the Mg porphyrin radical cation, by either electrochemical or chemical methods, quenches the free‐base porphyrin emission. Both quenching and tuning of the emission from the light‐collecting center can be fully reverted by redox or chemical stimuli.