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Dynamics of Closure of Zinc Bis‐Porphyrin Molecular Tweezers with Copper(II) Ions and Electron Transfer
Author(s) -
Habermeyer Benoit,
Takai Atsuro,
Gros Claude P.,
El Ojaimi Maya,
Barbe JeanMichel,
Fukuzumi Shunichi
Publication year - 2011
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.201101272
Subject(s) - porphyrin , copper , zinc , tweezers , electron transfer , ion , closure (psychology) , electron , molecular tweezers , chemistry , materials science , photochemistry , crystallography , organic chemistry , physics , crystal structure , supramolecular chemistry , quantum mechanics , economics , market economy
Zinc bis‐porphyrin molecular tweezers composed of a N 4 spacer bound through pyridyl units to the meso position of porphyrins were synthesized, and the tweezers are closed by the coordination of a copper(II) ion inside the spacer ligand. The effect of the π–π interaction between the porphyrin rings in the closed conformation on the absorption spectra of multi‐electron oxidized species and the reduction potentials were clarified by chemical and electrochemical oxidation of the closed form of the zinc bis‐porphyrin molecular tweezers in comparison with the open form without copper(II) ion and the corresponding porphyrin monomer. The shifts in redox potentials and absorption spectrum of the porphyrin dication indicate a strong electronic interaction between the two oxidized porphyrins in the closed form, whereas there is little interaction between them in the neutral form. The dynamics of copper(II) ion coordination and subsequent electron transfer was examined by using a stopped‐flow UV/Vis spectroscopic technique. It was confirmed that coordination of copper(II) occurs prior to electron‐transfer oxidation of the closed form of the zinc bis‐porphyrin molecular tweezers.