A macrocyclic effect on the reduction of p-quinones

Citation
H. Houjou et al., A macrocyclic effect on the reduction of p-quinones, SUPRAMOL CH, 13(6), 2001, pp. 683-692
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry
Journal title
SUPRAMOLECULAR CHEMISTRY
ISSN journal
1061-0278 → ACNP
Volume
13
Issue
6
Year of publication
2001
Pages
683 - 692
Database
ISI
SICI code
1061-0278(2001)13:6<683:AMEOTR>2.0.ZU;2-Z
Abstract
A macrocyclic compound that has four phenolic and four aromatic amino group s is synthesized. This compound reacts with p-quinones to give regiospecifi c oxidation products. During the reaction, the quinone is reduced to its hy droquinone form. The rate constant for the macrocycle is significantly larg e compared to its acyclic analogues. Analysis of the rate constants for sev eral p-quinones indicates that the rate determining step involves an electr on transfer process. Cyclic voltammetry measurement suggests that the compl exation of the macrocycle with the quinone is related to lowering of the ac tivation barrier of electron transfer. The role of the phenolic groups in t he complexation is discussed. Based on the experimental results, the macroc yclic effect is evaluated to be 27 kJ mol(-1) as the difference in Gibbs en ergy change necessary for the complexation.