Investigation on structurally different Cu(II) and Ni(II) complexes constructed from a novel pyridine-terminal salamo-like ligand

Abstract

A novel structurally characterized salamo-like ligand H2L contained double terminal pyridine groups was designed and synthesized. The single crystals of the Cu(II) and Ni(II) complexes are grown up through coordination of H2L with Cu(II) and Ni(II) ions, respectively, determined as [Cu(LH)]NO3⋅CH3CH2OH and [{Ni(L)}2]n·n3C5H5N·nCH3COCH3. The Cu(II) atom is located at the N2O2 cavity of the deprotonation ligand (L)2− moiety, but the N atoms of the terminal pyridine groups of the ligand (L)2− moiety is not involved in the coordination, and forms a four-coordinated twisted quadrilateral geometry. While the Ni(II) atom (Ni1 or Ni2) is sited in the N2O2 cavity of the deprotonation ligand (L)2− moiety and forms a plane, the terminal pyridine N atoms from the two adjacent [Ni(L)] moieties also coordinated with the Ni(II) atom in the axial positions to form a slightly distorted octahedral geometry with six-coordination. In the formation of MOFs, the benzene and pyridine rings of the ligand (L)2− moiety are rotated and create an angle, result to form a chiral MOFs using an achiral ligand (L)2− moiety. View of MOFs in the C direction, the Ni(II) complex has four different size of apertures in its structure, and presences a large amount of protonic hydrogen. Spectroscopic analyses of H2L and its Cu(II) and Ni(II) complexes are performed using IR, UV–Vis and fluorescence spectroscopy. Compared with the Cu(II) complex, the Ni(II) complex has better thermal stability. The magnetic analyses were also carried out. Hirshfeld surfaces analyses are carried out to analyze various short-range interactions in H2L and its Cu(II) complex.