A newly designed Co(II) complex, [Co₃(L)(OAc)₂(CH₃OH)₂]·CH₃OH, by the reaction of a bis(salamo)-type tetraoxime ligand (H₄L) with Co(II) acetate tetrahydrate was synthesized and characterized by elemental analyses, IR, UV-vis spectra and single-crystal X-ray crystallography. The UV-vis titration experiment manifested that a trinuclear (L:M = 1:3) complex was formed. It is worth noting that the two terminal Co(II) (Co1 and Co3) atoms of the Co(II) complex have different coordination modes and geometries unreported earlier. Furthermore, through intermolecular interactions (C–H···O, C–H···π and O–H···O), a 2D layer-like network is constructed. In addition, the fluorescence behaviors, antimicrobial activities and electrochemical properties of H₄L and its Co(II) complex were investigated.

A homo-dinuclear Cu(II) complex [Cu₂(L)₂] with the stoichiometric ratio of Cu(II) : (L)^2– = 2 : 2 was synthesized by the reaction of the ligand (4-methyl-6-aldehyde-6′-methoxy-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol) with Cu(OAc)₂·H₂O in the mixed CH₂Cl₂–MeOMe–EtOH solution (an unexpected ligand is the intermediate of condensation reaction of starting ligand with acetone). The Cu(II) complex was characterized by elemental analysis, IR, UV-Vis and X-ray crystallography. The Cu(II) complex crystallizes in monoclinic space group P2₁/n and consists of two Cu(II) atoms and two completely deprotonated ligand (L)^2– units. Through the analysis of intermolecular interactions, the Cu(II) complex units can form a 2D supramolecular structure through intermolecular hydrogen bonds and C–H···π interactions, respectively, meanwhile, the molecular interactions were quantitatively studied by Hirshfeld surfaces analyses. The fluorescence properties and DFT calculations were performed.