SYNTHESIS, STRUCTURE AND ANION COORDINATION CHEMISTRY OF A NOVEL MACROCYCLIC COBALTOCENIUM RECEPTOR

A new macrocyclic amide-substituted cobaltocenium receptor, 1,1′-[(ethylenedioxy)bis(ethyleneaminocarbonyl)]cobaltocenium hexafluorophosphate 2 has been prepared and its single-crystal X-ray structure determined. Proton NMR anion co-ordination studies revealed that 2 and other new acyclic cobaltocenium derivatives complex chloride and bromide anions with 1:1 stoichiometry. Comparative stability constant evaluations imply that the macrocyclic receptor 2 forms halide complexes of greatest thermodynamic stability, suggestive of a 'macrocyclic anion effect'. Cyclic voltammetric investigations showed the cobaltocenium receptors to electrochemically recognise halide anions

ACYCLIC REDOX RESPONSIVE ANION RECEPTORS CONTAINING AMIDE LINKED COBALTICINIUM MOIETIES

New acyclic redox responsive anion receptors containing amide linked cobalticinum moieties are prepared; preliminary anion coordination studies reveal that the combination of a positively charged cobalticinium unit together with an amide N-H group are the essential components for the molecular electro-chemical recognition of anionic guest species

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

New acyclic tripodal mono- and 1,1′-bis-substituted amide-linked cobaltocenium ligands have been prepared. Proton NMR spectroscopic and cyclic voltammetric anion co-ordination investigations reveal that the combination of a positively charged cobaltocenium unit together with an amide N-H group are the essential components for the molecular and electrochemical recognition of anionic guest species. Correlations were found to exist between Hammett σ p values of electron-donating and -withdrawing substituents of monosubstituted aryl amide cobaltocenium derivatives and relative magnitudes of halide-anion induced perturbations of the amide proton NMR chemical shift and cathodic shift of the respective cobaltocenium-cobaltocene reduction redox couple

DICARBOXYLATE ANION RECOGNITION BY A REDOX-RESPONSIVE DITOPIC BIS(COBALTICINIUM) CALIX[4]ARENE RECEPTOR MOLECULE

A novel calix[4]arene ditopic anion receptor molecule containing two cobalticinium moieties has been prepared and shown by 1H NMR and cyclic voltammetry to coordinate and electrochemically recognise anions including the dicarboxylate dianion adipate

ChemInform Abstract: New Classes of Anion Receptor Containing Charged and Neutral Transition Metal Lewis Acidic Recognition Sites.

A variety of new classes of anion receptor containing positively charged or neutral organometallic and coordination transition metal Lewis acidic binding sites in combination with amide N-H groups have been prepared and shown to complex halide anionic guest species

NEW CLASSES OF ANION RECEPTOR-CONTAINING CHARGED AND NEUTRAL TRANSITION-METAL LEWIS ACIDIC RECOGNITION SITES

A variety of new classes of anion receptor containing positively charged or neutral organometallic and coordination transition metal Lewis acidic binding sites in combination with amide N-H groups have been prepared and shown to complex halide anionic guest species

New pyridine N-oxides as chiral organocatalysts in the asymmetric allylation of aromatic aldehydes

Asymmetric allylation of aromatic aldehydes 1 with allyltrichlorosilane (2) can be catalyzed by new terpene-derived bipyridine N,N'-dioxides 12-15 and an axially chiral biisoquinoline dioxide 17b with good enantioselectivities. Dioxides have been found to be more reactive catalysts than their monooxide counterparts. Crown Copyright . All rights reserved