Structurally characterized homotrinuclear Salamo-type nickel(II) complexes: Synthesis, solvent effect and fluorescence properties

Four new solvent-induced Ni(II) complexes with chemical formulae [{NiL((2)-OAc)(MeOH)}(2)Ni]2MeOH (1), [{NiL((2)-OAc)}(2)(n-PrOH)(H2O)Ni]n-PrOH (2), [{NiL((2)-OAc)(DMF)}(2)Ni] (3) and [{NiL((2)-OAc)(DMSO)}(2)Ni]2DMSO (4), (H2L=4-Nitro-4-chloro-2,2-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol) have been synthesized and characterized by elemental analyses, FT-IR, UV-Vis spectra and X-ray crystallography. X-ray crystal structure determinations revealed that each of the Ni(II) complexes 1-4 consists of three Ni(II) atoms, two completely deprotonated (L)(2-) units, two (2)-acetate ions and two coordinated solvent molecules (solvents are methanol, n-propanol, water, N,N-dimethylformamide and dimethyl sulphoxide, respectively). Although the four complexes 1-4 were synthesized in different solvents, it is worthwhile that the Ni(II) atoms in the four complexes 1-4 adopt hexa-coordinated with slightly distorted octahedral coordination geometries, and the ratios of the ligand H2L to Ni(II) atoms are all 2: 3. The complexes 1-4 possess self-assembled infinite 1D, 3D, 1D and 2D supramolecular structures via the intermolecular hydrogen bonds, respectively. In addition, fluorescence behaviors were investigated in the complexes 1-4.