Two Gd₂ complexes, namely [Gd₂(dbm)₂(HL₁)₂(CH₃OH)₂]·4CH₃OH (1) and [Gd₂(dbm)₂(L₂)₂(CH₃OH)₂]·2CH₃OH (2), where H₃L₁=(Z)-N′-[4-(diethylamino)-2-hydroxybenzylidene]-2-hydroxyacetohydrazide, H₂L₂=(E)-N′- (5-bromo-2-hydroxy-3-methoxybenzylidene)nicotinohydrazide, Hdbm=dibenzoylmethane, have been constructed by adopting the solvothermal method. Structural characterization unveils that both complexes 1 and 2 are constituted by two Gd³⁺ ions, two dbm^- ions, two CH₃OH molecules, and two polydentate Schiff-base ligands (HL₁^2- or L₂^2-). In addition, complex 1 contains four free methanol molecules, whereas complex 2 harbors two free methanol molecules. By investigating the interactions between complexes 1 and 2 and four types of bacteria (Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Candida albicans), it was found that both complexes 1 and 2 exhibited potent antibacterial activities. The interaction mechanisms between the ligands H₃L₁, H₂L₂, complexes 1 and 2, and calf thymus DNA (CT-DNA) were studied using ultraviolet-visible spectroscopy, fluorescence titration, and cyclic voltammetry. The results demonstrated that both complexes 1 and 2 can intercalate into CT-DNA molecules, thereby inhibiting bacterial proliferation to achieve the antibacterial effects.

A tetranuclear Ho(Ⅲ)-based complex [Ho₄(L)₂(dbm)₆(CH₃O)₄] (1) was synthesized via solvothermal methods, where HL=(E)-2-hydroxy-3-methoxy-N′-[(6-methoxypyridin-2-yl)methylene]benzohydrazide and Hdbm=dibenzoylmethane. Structural characterization revealed that this complex is composed of four Ho³⁺ ions, six dbm^- ions, two L^- ions, and four coordinated CH₃O^- ions. The interaction mechanisms between ligand HL, 1 and calf thymus DNA (CT-DNA) were investigated by using UV-Vis spectroscopy, fluorescence titration, and cyclic voltammetry. The results indicated that 1 can interact with DNA via intercalation. Catalytic tests showed that 1 exhibits remarkable catalytic activity, capable of catalyzing the cycloaddition reaction of CO₂ with epoxides and the Knoevenagel condensation reaction between malononitrile and aldehydes.