Portal de Periódicos da CAPES

Mono- and bis-metallocene calix[4]arene hydrophobic receptor molecules; their synthesis, structure and electrochemical properties

1989; Elsevier BV; Volume: 378; Issue: 3 Linguagem: Inglês

10.1016/0022-328x(89)85368-9

1872-8561

Paul D. Beer, Anthony D. Keefe, Michael G. B. Drew,

Crystallography and molecular interactions

The condensation of ferrocene carbonylchloride (1) with p-t-butylcalix[4]arene (2) and calix[4]arene (3), and that of cobalticinium carbonylchloride chloride (6) with 2, leads to the corresponding new redox-active bis-ferrocene calix[4]arenes (4 and 5) and the mono-substituted cobalticinium analogue 7. An X-ray diffraction study of 5 shows the calix[4]arene is in a cone conformation. Cyclic voltammetric and coulometric studies in acetonitrile reveal that 4 and 5 undergo reversible two electron oxidations at +0.90 V (versus SCE), suggesting that the two respective ferrocene moieties are oxidised in one step; 7 exhibits a reversible one electron reduction at −0.45 V. Variable temperature 1H NMR studies show 4, 5 and 7 to exist in rigid cone conformations in solution. 1H NMR complexation studies (CD3CN) showed that none of the metallocene calix[4]arene receptors form solution host-guest complexes with t-butylamine and benzylamine.