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Electrochemical Implication of a Hydrogen‐Bonded Imidazole on a Redox‐Active‐Bound Phenolate Group
Author(s) -
El Ghachtouli Sanae,
LassalleKaiser Benedikt,
Guillot Régis,
Aukauloo Ally
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201402140
Subject(s) - chemistry , imidazole , protonation , ligand (biochemistry) , electrochemistry , redox , medicinal chemistry , substituent , stereochemistry , photochemistry , inorganic chemistry , organic chemistry , electrode , ion , biochemistry , receptor
We report the synthesis of a pentadentate N 4 O ligand with an imidazole group in the ortho position of the phenol group. The syntheses and crystallographic structures are reported for zinc(II) complexes by using the previously reported tert ‐butyl‐substituted ligand and the imidazole‐substituted ligand in two different protonation states. We describe the influence of the ortho substituent ( tert ‐butyl, imidazole, and imidazolium) on the electrochemical behavior of the zinc(II) complexes. The substitution of the tert ‐butyl group in the ortho position by an imidazole group shifts the oxidation potential of the phenolate by more than 300 mV. The o ‐ tert ‐butyl‐substituted ligand allows the formation of a stable radical phenoxylzinc(II) complex upon electrochemical oxidation, but it is unstable in the case of the imidazole‐substituted complex. The imidazole‐substituted ligand can be reversibly protonated without altering the electrochemical properties of the phenolate group.