Triple Halide Bridges in Chiral MnII2MnIII6NaI2 Cages: Structural and Magnetic Characterization

Manganese(II) complexes with 5-nitro-2-hydroxy-benzaldehyde or substituted 2-hydroxy-phenones: Structure and interaction with bovine serum albumin and calf-thymus DNA

A series of Mn(II) complexes of 5-nitro-salicyladehyde or substituted 2-hydroxy-phenones (HL) were synthesized in the absence or presence of a N,N'-donor co-ligand such as 2,2'-bipyridine, 1,10-phenanthroline, or 2,2'-bipyridylamine. The resultant coordination compounds were formulated as [Mn(L)₂(CH₃OH)₂] (1-3) and [Mn(L)₂(N,N'-donor)] (4-14), respectively, and characterized by diverse techniques. The crystal structures of three complexes were determined by single-crystal X-ray crystallography. Diverse techniques were employed to study the interaction of the complexes with calf-thymus DNA and showed intercalation as the most possible mode of their tight interaction. The affinity of the complexes for bovine serum albumin was investigated by fluorescence emission spectroscopy in order to calculate the binding constants which suggested a tight and reversible binding.

Dimensional Structures and Electrocatalytic Activities of Platinum(II)-Palladium(II)-Manganese(II) Coordination Polymers Controlled by Chloride versus Bromide

Here we report the synthesis and structural characterization of heterotrimetallic (Pt^II₂Pd^II₂Mn^II₂)_n coordination polymers that show different dimensionalities and electrocatalytic activities depending on chloride and bromide employed in the system. The reaction of the Pt^II₂Pd^II₂ tetranuclear complex [Pd₂Pt₂(NH₃)₄(d-pen)₄] (1), bearing free carboxylate groups, with Mn²⁺ in the presence of chloride produced the (Pt^II₂Pd^II₂Mn^II₂)_n coordination polymer [Mn₂Cl₂(H₂O)₆(1)]Cl₂ (2^Cl), in which the Pt^II₂Pd^II₂ units of 1 are linked by [MnCl(H₂O)₃]⁺ moieties in a 1:2 ratio to form a 2D sheetlike structure. The corresponding reaction in the presence of bromide also gave the (Pt^II₂Pd^II₂Mn^II₂)_n coordination polymer [Mn₂(H₂O)₆(1)]Br₄ (3^Br), but 3^Br adopted a 3D network structure via a 1:1 linkage of the Pt^II₂Pd^II₂ units with [Mn₂(H₂O)₆]⁴⁺ moieties. These complexes showed appreciably different electrocatalytic activities for H₂ evolution.

Chiral Versus Non-Chiral [MnIII 6 MnII NaI ], [MnIII 6 MnII 2 NaI 2 ] and [MnIII 3 MnII NaI ] Clusters Derived from Schiff Bases or the Fight for Symmetry

The reaction in basic media of manganese chloride with Schiff bases derived from the condensation of o-vanillin with different chiral/racemic aminoalcohols yielded in a family of complexes in which the nuclearity, symmetry and magnetic behavior is controlled by changing the position of the chiral carbon. Chiral and racemic clusters with [Mn^III ₆ Mn^II Na^I ], [Mn^III ₆ Mn^II ₂ Na^I ₂ ] and [Mn^III ₃ Mn^II Na^I ] metallic core have been structurally and magnetically characterized. The racemic clusters with an odd number of chiral ligands exhibit the anomalous mixing of ligands with different conformation. Related racemic compounds have been reviewed.

Two 1D homochiral heterometallic chains: crystal structures, spectra, ferroelectricity and ferromagnetic properties

Two new homo chiral Cu-Ln (Ln = Gd and Ho) compounds bearing a chiral Schiff base ligand (1R,3S)-N',N''-bis[3-methoxysalicylidene]-1,3-diamino-1,2,2-trimethylcyclopentane (H2L) have been synthesized and characterized by elemental analysis, IR spectroscopic and single-crystal X-ray diffraction techniques. The compounds were found to exhibit 1D zig-zag skeletons with double μ-1,5 bridging dicyanamide anions. Circular dichroism (CD) spectra have been used to verify their chiroptical activities. Magnetic studies suggest that 1 and 2 hold the same magnetic behavior with the dinuclear compounds presenting ferromagnetic interaction. Furthermore, both compounds show ferroelectricity with the remnant polarization (P r) value of 0.23 and 0.18 μC cm-2 at room temperature, respectively.

Na2MnIII6LnIII clusters with a non-equivalent core: chiral vs. meso isomerism

Chiral and racemic clusters with the Na₂MnIII6Ln^III core and different coordination numbers around the Ln^III cation provide rare examples of symmetry dependent isomerism.

Synthesis, Characterization and Magnetic Studies of a Tetranuclear Manganese(II/IV) Compound Incorporating an Amino-Alcohol Derived Schiff Base

A new tetranuclear mixed-valence manganese(II/IV) compound [MnIIMnIV3(μ-Cl)3(µ3-O)(L)3] (1) (where H3L = (3E)-3-((Z)-4-hydroxy-4-phenylbut-3-en-2-ylideneamino)propane-1,2-diol) has been synthesized and characterized by different physicochemical methods. Single crystal X-ray diffraction analysis reveals that 1 is a tetrahedral cluster consisting of a Mn4Cl3O4 core in which the only Mn(II) ion is joined through three μ2-O bridges to an equilateral triangle of Mn(IV) ions, which are connected by a μ3-O and three μ2-Cl bridges. The redox behavior of 1 was studied by cyclic voltammetry. Variable temperature magnetic susceptibility measurements of 1 revealed predominant antiferromagnetic coupling inside the Mn4Cl3O4 cluster.