New ionophoric calix[4]arenediquinones: coordination chemistry, electrochemistry and X-ray crystal structures

Beer, Paul D., Gale, Philip A., Chen, Zheng, Drew, Michael G.B., Heath, Jennifer A., Ogden, Mark I. and Powell, Harold R. (1997) New ionophoric calix[4]arenediquinones: coordination chemistry, electrochemistry and X-ray crystal structures. Inorganic Chemistry, 36, (25), 5880-5893. (doi:10.1021/ic9704851).


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A new library of ionophoric p-tert-butylcalix[4]diquinones containing ester (1), primary, secondary, and tertiary amide (2-4), and crown ether (5) substituents has been synthesized by treatment of the respective 1,3-bis-substituted p-tert-butylcalix[4]arene with Tl(OCOCF3)3 in trifluoroacetic acid. The structures of the free ligands 1 and 2, a p-tert-butylcalix[4]diquinone bridged at the lower rim by two linked veratrole groups (7), and a previously synthesized p-tert-butylcalix[4]diquinone bis(methyl ether) species (8) have been elucidated by X-ray crystallography. The X-ray crystal structures of 1-Sr(ClO4)2, 1-KClO4, 2-NaClO4, 4-n-BuNH3BF4, 5-NaOCOCF3, and 5-KPF6 demonstrate that these complexes adopt the cone conformation in the solid state. Interestingly, cation-quinone oxygen atom coordination occurs at both the upper and lower rim of 2-NaClO4 and 4-n-BuNH3BF4. Solution coordination properties have been studied by both 1H NMR and UV/vis techniques. The electrochemical properties of the "acyclic" p-tert-butylcalixdiquinones 1, 4, and 8 and their complexes have been studied using cyclic and square wave voltammetric techniques. The reduction potentials of the group 1 or 2 metal, ammonium, and alkylammonium complexes are significantly anodically shifted with respect to that of the free ligand. Addition of cations to electrochemical solutions of a p-tert-butylcalixdiquinone-crown-5 compound (5) caused large anodic shifts (by up to 555 mV in the presence of Ba2+) in a manner similar to that of the acyclic species.

Item Type: Article
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Subjects: Q Science > QD Chemistry
Divisions: University Structure - Pre August 2011 > School of Chemistry
ePrint ID: 15743
Date Deposited: 24 May 2005
Last Modified: 27 Mar 2014 18:06

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