Aerobic Oxidation Reactivity of Well-Defined CoII and CoIII Aminophenol Complexes

This article describes the synthesis and reactivity studies of three cobalt complexes bearing aminophenol-derived ligands without nitrogen substitution: CoII(tBu2APH)2(tBu2AP)2 (1), Co2III(tBu2APH)2(tBu2AP)2(μ-tBu2BAP)2 (2), and CoIII(tBu2AP)3 (3) (tBu2APH = 2-amino-4,6-di-tert-butylphenol, tBu2AP = 2-amino-4,6-di-tert-butylphenolate, μ-tBu2BAP = bridging 2-amido-4,6-di-tert-butylphenolate). Stoichiometric reactivity studies of these well-defined complexes demonstrate the catalytic com-petency of both CoII and CoIII complexes in the aerobic oxidative cyclization of tBu2APH with tert-butyl isonitrile. Reactions with O2 reveal the aerobic oxidation of CoII complex 1 to generate the CoIII species 2 and 3. UV-visible time-course studies and EPR spectroscopy indicate that this oxidation proceeds through a ligand-based radical intermediate. These studies repre-sent the first example of well-defined cobalt-aminophenol complexes that participate in catalytic aerobic oxidation reactions and highlight a key role for a ligand radical in the oxidation sequence.

A trapped hexaaqua CoII complex between the polyanionic sheets of decavanadate reveals high axial anisotropy and field induced SIM behaviour

A hexaaqua CoII complex within the anionic metal oxide cluster of decavanadates reveals easy-axis anisotropy and field induced SIM behaviour with a high energy barrier for the spin reversal process.

Microwave-assisted synthesis: from a mononuclear {CoII} complex to {CoII9} solvomorphs

Microwave-assisted control over nuclearity and solvomorphism.

Structural characterization and Hirshfeld surface analysis of a CoII complex with imidazo[1,2-a]pyridine

A new mononuclear tetrahedral CoII complex, dichloridobis(imidazo[1,2-a]pyridine-κN 1)cobalt(II), [CoCl2(C7H6N2)2], has been synthesized using a bioactive imidazopyridine ligand. X-ray crystallography reveals that the solid-state structure of the title complex exhibits both C—H...Cl and π–π stacking interactions in building supramolecular assemblies. Indeed, the molecules are linked by C—H...Cl interactions into a two-dimensional framework, with finite zero-dimensional dimeric units as building blocks, whereas π–π stacking plays a crucial role in building a supramolecular layered network. An exhaustive investigation of the diverse intermolecular interactions via Hirshfeld surface analysis enables contributions to the crystal packing of the title complex to be quantified. The fingerprint plots associated with the Hirshfeld surface clearly display each significant interaction involved in the structure, by quantifying them in an effective visual manner.

Correction: The biological in vitro effect and selectivity shown by a CoII complex of 2-(2-hydroxyphenylazo)-indole-3′-acetic acid on three distinctly different cancer cells

Correction for ‘The biological in vitro effect and selectivity shown by a CoII complex of 2-(2-hydroxyphenylazo)-indole-3′-acetic acid on three distinctly different cancer cells’ by Durba Ganguly et al., RSC Adv., 2016, 6, 114906–114915.

A CoII complex for 19F MRI-based detection of reactive oxygen species

A fluorinated, cobalt(ii)-based 19F MRI imaging agent switches from a paramagnetic high spin CoII state to a diamagnetic low spin CoIII state following oxidation by H2O2 and other reactive oxygen species, resulting in a turn-on response via both 19F NMR and MRI.