Multi Redox-active Macrocyclic Host Molecules containing Multiple Benzo Crown Ether and Ferrocenyl Moieties that bind Bipyridinium Dications: Syntheses, Co-ordination and Electrochemical Properties

DOI: 10.1039/DT9910001691

Source and publish data:

Journal of the Chemical Society, Dalton Transactions p. 1691 - 1698 (1991)

Update date:2022-08-03

Topics:

Authors:

Beer, Paul D.

Tite, E. Louise

Ibbotson, Arthur

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Article abstract of DOI:10.1039/DT9910001691

The design, syntheses, co-ordination and electrochemical properties of novel multisite host molecules containing multiple benzo crown ether and ferrocenyl redox centres are described.The reaction of the macrocycle 2,8,14,20-tetraferrocenylpentacyclo<19.3.1.1^3,7.1^9,13.1^15,19>octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaen-4,6,10,12,16,18,22,24-octol 3 with propionic anhydride, benzoyl chloride or chlorocarbonylferrocene 6 gave new redox-active host molecules 4, 5 and 7 respectively.The acid-catalysed condensation of 15-formyl-2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecine with 1,3-dihydroxybenzene afforded a novel phenolic macrocycle 2,8,14,20-tetrakis(2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecin-15-yl)-pentacyclo<19.3.1.1^3,7.1^9,13.1^15,19>octacosa-1(25),3,5,7(28),9,11,13(27),15,17,19(26),21,23-dodecaen-4,6,10,12,16,18,22,24-octol 14 which on reaction with propionic anhydride, benzoyl chloride, 6 or bromochloromethane gave respective host molecules 15, 16, 17 and 18 (the latter being the first crown ether cavitand host), each containing four benzo-15-crown-5 moieties.Electrochemical studies show the four ferrocenyl redox centres present in 5 to undergo two one-electron oxidations at +0.58 and +0.67 V in dichloromethane.Redox-active host 17, containing eight ferrocenyl moieties, was found to undergo independent reversible one-electron oxidations in dichloromethane.High-field 1H NMR complexation studies revealed hosts 16-18 to form solution complexes with bipyridinium guest species, exclusively at the host's benzo crown ether binding site.