A study on two unusual heterohexanuclear [CuII4LnIII2] (LnIII = LaIII and CeIII) complexes with a N2O2- and O6-donor bis(salamo)-based ligand

Two unusual heterobimetallic [CuII4LnIII2] complexes were constructed from a N2O2- and O6-donor bis(salamo)-based ligand (H4L), and characterized structurally. The intermolecular interactions were quantitatively analyzed by Hirshfeld surfaces, as well as, fluorescence properties have also been studied. [Display omitted] •Two structurally novel heterobimetallic hexanuclear [CuII4LnIII2] complexes were prepared using a designed N2O2- and O6-donor bis(salamo)-based ligand.•The different natures of three-compartmental H4L lead to the site‐selective introduction of two various metalII/III atoms.•Quantitative analyses of intermolecular interactions were evaluated by Hirshfeld surfaces analyses.•The fluorescence properties were further discussed. Two unusual heterobimetallic [CuII4LnIII2] complexes, [{Cu4(L)2La2(ƞ2-NO3)6(EtOH)}]·2Me2CO (1) and [{Cu4(L)2Ce2(ƞ2-NO3)6(EtOH)}2]·4Me2CO·MeOH (2) were constructed from a N2O2- and O6-donor bis(salamo)-based ligand (H4L). The structures were characterized by physical chemistry and spectroscopy methods. The two complexes 1 and 2 have similar structures, two heterotrinuclear parts with the same structure are linked by the coordination between one CuII atom and oxime-type oxygen atoms to obtain the heterohexanuclear complexes 1 and 2. Four penta-coordinate CuII atoms are located at the N2O2 cavities of the ligand (L)4- units, two LaIII/CeIII atoms are surrounded by the open-chain 18-crown-6 (O6) coordination environment. At the same time, eight bridged phenol oxygen atoms connect the six CuII/LnIII atoms. Infinite three-dimensional supra-molecular structures are formed in complexes 1 and 2 through H-bonds. The intermolecular interactions were quantitatively analyzed by Hirshfeld surfaces, as well as, fluorescence properties have also been studied.