Mn(II) complexes of three [2+2] macrocyclic Schiff base ligands. Synthesis and X-ray crystal structure of the first binuclear–di(binuclear) cocrystal

Crystal Structures, Photoluminescence, and Magnetism of Two Novel Transition-Metal Complex Cocrystals with Three-Dimensional H-Bonding Organic Framework or Alternating Noncovalent Anionic and Cationic Layers

Cocrystallization may alter material physicochemical properties; thus, the strategy of forming a cocrystal is generally used to improve the material performance for practical applications. In this study, two transition-metal complex cocrystals [Zn(bpy)₃]H_0.5BDC·H_1.5BDC·0.5bpy·3H₂O (1) and [Cu₂(BDC)(bpy)₄]BDC·bpy·2H₂O (2) have been achieved using a hydrothermal reaction, where bpy and H₂BDC represent 2,2'-bipyridine and benzene-1,3-dicarboxylic acid, respectively. Cocrystals were characterized by microanalysis, infrared spectroscopy, and UV-visible spectroscopy. Cocrystal 1 contains five components and crystallizes in a monoclinic space group P2₁/n. The H_0.5BDC^1.5-, H_1.5BDC^0.5-, and H₂O molecules construct three-dimensional H-bonding organic framework; the [Zn(bpy)₃]²⁺ coordination cations and uncoordinated bpy molecules reside in channels, where two coordinated bpy ligands in [Zn(bpy)₃]²⁺ and one uncoordinated bpy adopt sandwich-type alignment via π···π stacking interactions. Cocrystal 2 with four components crystallizes in a triclinic space group P-1 to form alternating layers; the binuclear [Cu₂(bpy)₄(BDC)]²⁺ cations and uncoordinated bpy molecules build the cationic layers, and the BDC^2- species with disordered lattice water molecules form the anionic layers. Cocrystal 1 shows intense photoluminescence at an ambient condition with a quantum yield of 14.96% and decay time of 0.48 ns, attributed to the π* → π electron transition within phenyl/pyridyl rings, and 2 exhibits magnetic behavior of an almost isolated spin system with rather weak antiferromagnetic coupling in the [Cu₂(bpy)₄(BDC)]²⁺ cation.

Manganese coordination chemistry of bis(imino)phenoxide derived [2 + 2] Schiff-base macrocyclic ligands

Products resulting from the reaction of MnCl₂ with [2 + 2] Schiff-base macrocycles have been structurally characterized, and were found to be poorly active for the ROP of ε-caprolactone.

Mimicking Peroxidase Activity by a Manganese(II) Complex Involving a New Asymmetric Tetradentate Ligand Containing Both Amino and Imino Groups

The asymmetric ligand (E)-4-bromo-2-(((2-((5-bromo-2-hydroxybenzyl)(methyl)amino)ethyl)imino)methyl)phenol has been prepared by a novel seven-step route. All organic compounds isolated in each step have been characterised by elemental analysis, infrared and1H NMR spectroscopy, and mass spectrometry. Interaction of this ligand with manganese has been investigated employing an electrochemical method. This method leads to the formation of a neutral manganese(II) complex7in high yield and purity. The complex has been thoroughly characterised by elemental analysis, infrared spectroscopy, mass spectrometry, magnetic susceptibility measurements, and cyclic voltammetry. Complex7behaves as peroxidase mimic in the presence of the water-soluble trap ABTS, probably due to its ease to coordinate the substrate molecule.