Synthesis, X-ray structure and catecholase activity of an antiferromagnetically coupled trinuclear nickel(II) complex

Templated synthesis of Ni(ii) complexes of unsymmetrical Schiff base ligands derived from 1,3-diamino-2-propanol: structural diversity and magnetic properties

A Ferromagnetically coupled tetranuclear, an antiferromagnetically coupled hexanuclear and a mononuclear Ni(II) complex of new unsymmetrical Schiff base ligands derived from 1,3-diamino-2-propanol have been obtained with a slight change in the carbonyl compounds.

A trinuclear nickel(II) Schiff base complex with phenoxido- and acetato-bridges: combined experimental and theoretical magneto-structural correlation

We describe the synthesis and characterization of a new trinuclear Ni(ii) Schiff base complex of formula [Ni3(L)2(NCS)2(OAc)2(CH3OH)2] (1) where HL is the 1 : 1 condensation product of 2-picolylamine and o-vanillin. The crystal structure of complex 1 shows that the two terminal Ni(ii) ions are connected to the central one through a phenoxido- and a syn-syn acetato bridge, giving rise to a very bent configuration in the Ni3-core. Magnetic susceptibility measurements show the presence of a weak antiferromagnetic coupling with J = -3.22(2) cm-1. We also report a magneto-structural correlation, performed with all the magnetically characterized Ni(ii) trimers with similar bridges, showing a linear dependence between the J value and the dihedral angle (θ) between the planes containing the Ni-O-Ni and the carboxylate bridges. The super-exchange interaction is investigated by extensive density functional calculations within the broken symmetry approximation which show good agreement with the experimental data. The analysis of the spin density distribution and the shape of the magnetically active single occupied molecular orbitals (SOMO) provide a mechanism of exchange coupling through the bridging groups.

Structural diversity, magnetic properties, and luminescence sensing based Ni(ii)/Zn(ii) coordination polymers of the semirigid 3,3′-((5-carboxy-1,3-phenylene)bis(oxy))dibenzate ligand

Four novel CPs were synthesized and two Zn(ii)-CPs can be used as fluorescent probes for the detection of CrO₄²⁻/Cr₂O₇²⁻.

Structural diversity, magnetic properties and luminescence of NiII, CoII and ZnII coordination polymers derived from 3,3'-[(5-carboxy-1,3-phenylene)bis(oxy)]dibenzoic acid and 1,10-phenanthroline

Three novel coordination polymers (CPs), namely poly[[di-μ-aqua-bis{μ₄-3,3'-[(5-carboxylato-1,3-phenylene)bis(oxy)]dibenzoato-κ⁵O¹:O^1',O³:O⁵:O^5'}bis(1,10-phenanthroline-κ²N,N')trinickel(II)] dimethylformamide 1.5-solvate trihydrate], {[Ni₃(C₂₁H₁₁O₈)₂(C₁₂H₈N₂)₂(H₂O)₂]·1.5C₃H₇NO·3H₂O}_n, (I), poly[[di-μ-aqua-bis{μ₄-3,3'-[(5-carboxylato-1,3-phenylene)bis(oxy)]dibenzoato-κ⁵O¹:O^1',O³:O⁵:O^5'}bis(1,10-phenanthroline-κ²N,N')tricobalt(II)] diethylamine disolvate tetrahydrate], {[Co₃(C₂₁H₁₁O₈)₂(C₁₂H₈N₂)₂(H₂O)₂]·2C₂H₇N·4H₂O}_n, (II), and catena-poly[[aqua(1,10-phenanthroline-κ²N,N')zinc(II)]-μ-5-(3-carboxyphenoxy)-3,3'-oxydibenzoato-κ²O¹:O³], [Zn(C₂₁H₁₂O₈)(C₁₂H₈N₂)(H₂O)]_n, (III), have been synthesized by the reaction of different metal ions (Ni²⁺, Co²⁺ and Zn²⁺), 3,3'-[(5-carboxy-1,3-phenylbis(oxy)]dibenzoic acid (H₃cpboda) and 1,10-phenanthroline (phen) under solvothermal conditions. All the CPs were characterized by elemental analysis, single-crystal and powder X-ray diffraction, FT-IR spectroscopy and thermogravimetric analysis. Complexes (I) and (II) have isomorphous structures, featuring similar linear trinuclear structural units, in which the central Ni^II/Co^II atom is located on an inversion centre with a slightly distorted octahedral [NiO₆]/[CoO₆] geometry. This comprises four carboxylate O-atom donors from two cpboda^3- ligands and two O-atom donors from bridging water molecules. The terminal Ni^II/Co^II groups are each connected to the central Ni^II/Co^II cation through two μ_1,3-carboxylate groups from two cpboda^3- ligands and one water bridge, giving rise to linear trinuclear [M₃(μ₂-H₂O)₂(RCOO)₄] (M = Ni²⁺/Co²⁺) secondary building units (SBUs) and the SBUs develop two-dimensional-networks parallel to the (100) plane via cpboda^3- ligands with new (3²·4)₂(3²·8³·9)₂(3⁴·4².8²·9⁴·10³) topological structures. Zinc complex (III) displays one-dimensional coordination chains and the five-coordinated Zn atom forms a distorted square-pyramidal [ZnO₃N₂] geometry, which is completed by two carboxylate O-atom donors from two distinct Hcpboda^2- ligands, one O atom from H₂O and two N atoms from a chelating phen ligand. Magnetically, CP (I) shows weak ferromagnetic interactions involving the carboxylate groups, and bridging water molecules between the nickel(II) ions, and CP (II) shows antiferromagnetic interactions between the Co²⁺ ions. The solid-state luminescence properties of CP (III) were examined at ambient temperature and the luminescence sensing of Cr₂O₇^2-/CrO₄^2- anions in aqueous solution for (III) has also been investigated.