Mononuclear Zn(II) and trinuclear Ni(II) complexes derived from a coumarin-containing N2O2 ligand: Syntheses, crystal structures and fluorescence properties

Two newly designed fluorescent complexes, [Zn(L)(MeOH)]·CH2Cl2 (1) and [{NiL(MeOH)(μ-OAc)}2Ni]·4CH2Cl2 (2) based on a coumarin-containing N2O2 chelating ligand H2L have been synthesized and characterized by elemental analyses, IR and UV–Vis spectra, fluorescence spectra and X-ray crystallography. Complex 1 includes one Zn(II) atom, one completely deprotonated (L)2− unit, one coordinated methanol molecule and one crystalling dichloromethane molecule, and forms an infinite 2D supramolecular network. While complex 2 contains three Ni(II) atoms, two completely deprotonated (L)2− units, two μ2-acetate ions, two coordinated methanol molecules and four crystalling dichloromethane molecules, and possesses an infinite 3D supramolecular structure. The fluorescence titration experiment is used to characterize fluorescence properties of complexes 1 and 2. The normalized fluorescent spectra show clearly that complexes 1 and 2 have favorable fluorescent emissions in different solvents.