Syntheses, crystal structures, Hirshfeld surface analyses and fluorescence of binuclear complexes with unsymmetrical phenol-based compartmental ligands

Two new binuclear complexes, [Ni₂L(OAc)₂(H₂O)]ClO₄·H₂O·CH₂Cl₂ (1) and [Zn₂L(OAc)₂]ClO₄·CHCl₃·0.5C₆H₁₂ (2), have been synthesized by using 2-[N,N-di(2-pyridylmethyl)aminomethyl]-6-(2-imidazolylmethyl)aminomethyl-4-methylphenol (HL) as a ligand. Complexes 1 and 2 have been characterized by FT-IR, powder X-ray diffraction, elemental analysis and single-crystal X-ray diffraction. X-ray crystallographic analyses show that 1 crystallizes in the triclinic P-1 space group, while 2 in the monoclinic C2/c space group. Both Ni1 and Ni2 in 1 are six-coordinate octahedra with a [Ni1O₃N₃] and [Ni2O₄N₂] configuration. In 2, the six-coordinate Zn1 cation displays a distorted octahedral [Zn1O₃N₃] configuration, while the five-coordinate Zn2 cation has a trigonal bipyramidal [Zn2O₂N₃] geometry. The intermolecular interactions in 1 and 2 have been investigated by 3D Hirshfeld surface analyses and 2D fingerprint plots to show that the prominent interactions are H···H and O···H/H···O contacts in 1 and H···H and Cl···H/H···Cl contacts in 2. Notably, the fluorescence emission of 2 has larger intensity than that of the free HL.