Symmetric containing-PMBP N2O2-donors nickel(II) complexes: Syntheses, structures, Hirshfeld analyses and fluorescent properties

One mononuclear Ni(II) complex [Ni(L1)(MeOH)2]·MeOH (1) and two novel trinuclear Ni(II) complexes [Ni3(L2)3(EtOH)6] (2) and [Ni3(L2)3(H2O)6] (3) constructed from symmetric N2O2-donors chelating ligands (H2L1 and H2L2) were synthesized and characterized by elemental analyses, FT-IR, UV–Vis spectra and fluorescence spectra. The structures of all three complexes were confirmed by single crystal X-ray diffraction analyses. Complex 1 includes one Ni(II) atom, one completely deprotonated (L1)2− unit and two coordinated methanol molecules, and forms an infinite 2D supramolecular network via the intermolecular hydrogen bonds. While complex 2 or 3 is trinuclear with three Ni(II) atoms, three completely deprotonated (L2)2− units and six coordinated ethanol or H2O molecules. These self-assembling complexes form different dimensional supramolecular structures through inter- and intramolecular hydrogen bonds. Hirshfeld surface analyses for complexes 1, 2 and 3 were mapped with various functions and further quantification of intermolecular interactions was made through the generation of 2D fingerprint plots. In addition, the fluorescence titration experiments were used to characterize fluorescence properties of complexes 1 and 2.