Syntheses, characterizations, and crystal structures of 3d–s/d10 metal complexes derived from two compartmental Schiff base ligands

Compartmentalization of Alkaline-Earth Metals in Salen-Type Cu- and Ni-Complexes in Solution and in the Solid State

The precise arrangement of metal ions in type and number by a ligand represents an important challenge in biology as well as in materials science. The preorganization of different metal ions such as alkaline-earth and transition-metal ions is of particular interest for the design of catalysts or precursors of oxides. This study is based on a Ω-shaped salen-derived ligand comprising N2O2 and O2O2 coordination sites. The selective binding of Cu(II) and Ni(II) and alkaline-earth-metal ions is influenced by many factors such as the size of the cation, the solvent, or the counterion. UV-vis and 1H NMR titrations and single-crystal X-ray structures reveal that the obtained complexes tend to adopt different structures in solution compared to the solid state. Mainly discrete motifs with a stoichiometry 1:1 (LM1 to alkaline-earth-metal ions) have been shown to form in the solid state, whereas in solution, the 2:1 complexes are predominant.

A new co-crystal dinuclear/trinuclear ZnII-ZnII/ZnII-SmIII-ZnII complex with a salen-type Schiff base ligand

In the penta-nuclear title complex, [SmZn2(C22H18N2O4)2(NCS)2(C3H7NO)2][Zn2(C22H18N2O4)(NCS)3]·C3H7NO·0.32H2O, namely bis-{μ2-6,6'-dimeth-oxy-2,2'-[phenyl-ene-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}-1κ4 O,N,N',O':2κ3 O,O',O 6;2κ3 O,O',O 6:3κ4 O,N,N',O'-bis-(di-methyl-formamide-2κO)di-thiocyanato-1κN,3κN-2-samarium(III)-1,3-dizinc(II) {μ2-6,6'-dimeth-oxy-2,2'-[phenyl-ene-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-1κ4 O,N,N',O':2κ2 O,O'}trithio-cyan-ato-1κN;2κ2 N,N-dizinc(II) di-methyl-formamide monosolvate 1.32-hydrate, a dinuclear unit and a trinuclear unit co-exist. One of the ZnII centers in the dinuclear unit as well as the two ZnII centers in the trinuclear unit are located in the inner N2O2 cavity of the ligand and are coordinated to the nitro-gen atom of one thio-cyanate moiety, giving rise to a square-pyramidal geometry. The second ZnII center in the dinuclear unit is coordinated to the two phenolate oxygen atoms of the ligand and to two thio-cyanate groups via the nitro-gen atom in a tetra-hedral geometry. The SmIII ion is eight-coordinated by four phenolate O atoms from the two ligand mol-ecules, two meth-oxy O atoms from the two ligand mol-ecules and two O atoms from the DFM solvent mol-ecule. In the dinuclear unit, the two meth-oxy oxygen atoms remain uncoordinated while in the trinuclear unit, for each ligand one meth-oxy oxygen is coordinated and the other one remains uncoordinated. In the crystal, the trinuclear cationic units and dinuclear anionic units are assembled into infinite layers. These layers are held together via electrostatic inter-actions, forming a three-dimensional structure. In the dinuclear unit, the C and S atoms of one of the thio-cyanate groups are disordered over two sets of sites in a 0.680 (4)(4):0.320 (4) ratio.

Syntheses, crystal structures, magnetic properties and ESI-MS studies of a series of trinuclear CuIIMIICuII compounds (M = Cu, Ni, Co, Fe, Mn, Zn)

Six trinuclear CuIIMIICuII compounds (M = Cu, Ni, Co, Fe, Mn, Zn) derived from the Schiff base ligand, H2L (2 + 1 condensation product of salicylaldehyde and trans-1,2-diaminocyclohexane) are reported in this investigation. The composition of the metal complexes are [{CuIIL(ClO4)}2CuII(H2O)]·2H2O (1), [{CuIIL(ClO4)}{NiII(H2O)2}{CuIIL}]ClO4·CH3COCH3 (2), [{CuIIL(ClO4)}{CoII(CH3COCH3)(H2O)}{CuIIL(CH3COCH3)}]ClO4 (3) and isomorphic [{CuIIL(ClO4)}2MII(CH3OH)2] (4, M = Fe; 5, M = Mn; 6, M = Zn). Two copper(ii) ions in 1-6 occupy N2O2 compartments of two L2- ligands, while the second metal ion occupies the O(phenoxo)4 site provided by the two ligands, i.e., the two metal ions in both CuIIMII pairs are diphenoxo-bridged. Positive ESI-MS of 1-6 reveals some interesting features. Variable-temperature and variable-field magnetic studies reveal moderate or weak antiferromagnetic interactions in 1-6 with the following values of magnetic exchange integrals (H = -2JS 1 S 2 type): J 1 = -136.50 cm-1 and J = 0.00 for the CuIICuIICuII compound 1; J 1 = -22.16 cm-1 and J = -1.97 cm-1 for the CuIINiIICuII compound 2; J 1 = -14.78 cm-1 and J = -1.86 cm-1 for the CuIICoIICuII compound 3; J 1 = -6.35 cm-1 and J = -1.17 cm-1 for the CuIIFeIICuII compound 4; J 1 = -6.02 cm-1 and J = -1.70 cm-1 for the CuIIMnIICuII compound 5; J = -2.25 cm-1 for the CuIIZnIICuII compound 6 (J is between two CuII in the N2O2 compartments; J 1 is between CuII and MII through a diphenoxo bridge).

Theoretical and experimental investigation of anticancer activities of an acyclic and symmetrical compartmental Schiff base ligand and its Co(ii), Cu(ii) and Zn(ii) complexes

A compartmental Schiff base ligand, 2,2′-((((((2-hydroxypropane-1,3-diyl)bis(oxy))bis(2,1-phenylene))bis(methylene))bis(azanylylidene))bis(methanylylidene))bis(4-bromophenol) (H₃L^Br) and its complexes with cobalt(ii), copper(ii) and zinc(ii) including, [Co(HL^Br)] (1), [Cu₂(L^Br)(μ-1,3-OAc)]·MeOH (2) and [Zn(HL^Br)] (3) were prepared using template synthesis and characterised by elemental analysis, FT-IR and ¹H NMR spectroscopies and single-crystal X-ray diffraction. In the structure of complexes 1 and 3 the metal atom has a MN₂O₂ environment with tetrahedral geometry while complex 2 has a binuclear structure with a MNO₄ environment and square planar geometry around the copper atom. The ability of all compounds to interact with the nine biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS and Top II) are investigated by docking calculations. For examination of the docking results, the in vitro activities of eight compounds against the human leukemia cell line K562 was investigated by evaluation of IC₅₀ values and mode of cell death (apoptosis).

A compartmental Schiff base ligand and its copper, cobalt and zinc complexes were prepared. The in vitro activities of all compounds against the human leukemia cell line K562 were investigated along with docking and DFT studies.

Trigonal dodecahedral sodium coordination in a trinuclear copper(II)-sodium complex incorporating a salen-type compartmental Schiff base

A new trinuclear heterometallic complex, [(CuL)Na(CuL)]·ClO4 (1), has been prepared using a Schiff base, H2L (where H2L=N,N′-(1,2-phenylene)-bis(3-methoxysalicylideneimine) and characterized by elemental analysis, Fourier transform infra-red (FT-IR) spectroscopy, UV/Vis, magnetic, electrochemical, and single crystal X-ray diffraction methods. The structure analysis reveals that two metallo-ligand [(CuL)] units are connected to each other by a sodium ion resulting in the cationic unit [(CuL)Na(CuL)]+. Both the copper(II) ions display an almost square planar geometry while the sodium ion adopts a trigonal-dodecahedral coordination geometry. The spectroscopic and other physicochemical studies are in good agreement with the crystal structure of the complex.