A NOVEL TETRANUCLEAR NICKEL(II) SALAMO-BASED COMPLEX ADOPTING TWO OPEN CUBIC STRUCTURES: SYNTHESIS, CHRACTERIZATION, DFT CALCULATION, HIRSHFELD ANALYSIS, AND FLUORESCENT PROPERTIES

Abstract

A novel tetranuclear Ni(II) complex [Ni4(L)2(N3)4Cl(MeOH)3]·CH3COCH3 is synthesized via a symmetrical salamo-based ligand H2L, NiCl2·6H2O, and NaN3. The structure is characterized by elemental analyses, IR and UV-Vis spectroscopy, and X-ray diffraction analysis. The X-ray crystal analysis shows that Ni(II) atoms in the Ni(II) complex have distorted octahedral geometries. It is the key factor that the ligand containing 3-position methoxy groups gives rise to the formation of the tetranuclear Ni(II) complex. When \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\text{NO}_{3}^{-}$$\\end{document} anions are used to bridge two Ni2 atoms, there are two symmetrical open cubic structures. The Ni(II) complex forms a 3D supramolecular structure through intermolecular hydrogen bond interactions. Using the Hirshfeld surface to clarify interactions between the molecules, the percentages of C–H/H–C, O–H/H–O, and H–H/H–H contacts are calculated as 19.0%, 15.3%, and 54.0%, respectively. Density functional theory (DFT) studies show that the stability of the Ni(II) complex is much higher than that of H2L. The calculation of the fluorescence titration experiment can give K = 1.05·108 M–1, which further proves the stability of the Ni(II) complex.