M. Isabel Fernández

A new type of manganese-Schiff base complex, catalysts for the disproportionation of hydrogen peroxide as peroxidase mimics

New manganese(II) and manganese(III) complexes of substituted N,N′-bis(salicylidene)-1,2-diimino-2-methylethane have been prepared and characterized. Elemental analysis, IR and EPR spectroscopies, mass spectrometry, magnetic measurements and the study of their redox properties have confirmed their respective formulae as MnIIL(H2O)2 and MnIIIL(H2O)n(ClO4). Electron-withdrawing substituents on the phenyl rings of the ligand stabilize the oxidation state (II) for manganese, but the electron-donating substituents on the Schiff bases are those that lead to Mn(III) complexes, which behave as efficient peroxidase mimics in the presence of the water-soluble trap ABTS. The rate of peroxidase activity of the present complexes is significantly higher than that of other series of Mn-Schiff base compounds, probably due to their versatility in adopting in solution a structure that allows the coordination of the hydrogen peroxide substrate molecule to the manganese.

Novel Manganese(III) Complexes with the Schiff Base N,N′‐(1,2‐Phenylene)‐bis(3‐Hydroxysalicylidenimine)

Four novel manganese(III) complexes have been prepared using the tetradentate ONNO symmetrical Schiff base N,N′‐(1,2‐phenylene)‐bis(3‐hydroxysalicylidenimine) H4L and employing different manganese(II) and manganese(III) starting salts (chloride, acetate, acetylacetonate and perchlorate). These complexes were thoroughly characterised by elemental analysis, ES mass spectrometry, infrared and paramagnetic 1H NMR spectroscopies, magnetic susceptibility measurements and molar conductivities. Electrochemical studies by cyclic and normal pulse voltammetry were also performed. All complexes obtained are manganese(III) ones, in which the anions belonging to the starting salts have diverse coordinating tendencies; this fact seems to determine the nuclearity of the final complexes, with empirical formulae [Mn(H2L)(H2O)2]Cl(H2O)3 1, [Mn(H2L)(OAc)](H2O) 2, [Mn(H2L)(acac)](H2O)3 3, and [Mn(H2L)(H2O)(CH3OH)](ClO4) 4. The X‐ray crystal structure of H4L Schiff base has been determined.

Complexes of TlClI2 with Aromatic Amine Oxides

Abstract The following compounds: TlClI2 (PyO)2; TlClI2(2-PicO)2; TlClI2(3-PicO)2; TlClI2(4-PicO)2; TlClI2(4-Cl-PyO)2; TlClI2 (4-CN-PyO)2; TlClI2(4-NO2-PyO)2 and TlClI2 (4-CH3O-PyO)2 have been prepared and characterized by elemental analysis. The solids behave as monomers and non-electrolytes in solution. Possible molecular structures are given on the basis of 1H NMR and lR spectra, with particular attention on the νTl-X and νTl-O strectching modes.

Supramolecular self-assembly of a symmetric imine ligand functionalized with a dansyl fluorophore moiety

We report the synthesis and characterization of a symmetric [N4] tetradentate imine-type ligand H2L that incorporates a dansyl fluorophore group in both ligand arms. Two binding domains separated by a short arene spacer and two bulky arms with an anti conformation make this organic molecule suitable as precursor of metallosupramolecular species such as helicates. The molecular structure of H2L has been analyzed by X-ray diffraction. This technique has revealed the formation of intermolecular hydrogen bond interactions that lead to the supramolecular self-assembly of ligand molecules in the solid state and the generation of oval-shaped channels in the 3D crystal packing.