ANION RECOGNITION BY ACYCLIC REDOX-RESPONSIVE AMIDE-LINKED COBALTOCENIUM RECEPTORS

New acyclic tripodal mono- and 1,1'-bis-substituted amide-linked cobal tocenium ligands have been prepared. Proton NMR spectroscopic and cycl ic voltammetric anion co-ordination investigations reveal that the com bination of a positively charged cobaltocenium unit together with an a mide N-H group are the essential components for the molecular and elec trochemical recognition of anionic guest species. Correlations were fo und to exist between Hammen sigma(p) values of electron-donating and - withdrawing substituents of monosubstituted aryl amide cobaltocenium d erivatives and relative magnitudes of halide-anion induced perturbatio ns of the amide proton NMR chemical shift and cathodic shift of the re spective cobaltocenium-cobaltocene reduction redox couple.