Multifunctional Ln2 compounds with butterfly-shaped structures: Remarkable Single-Molecule Magnet behaviors, and biological activities

The efficient design and reasonable construction of multifunctional Ln(III)-based compounds with fascinating structures have always attracted great concern, and it is also an immense challenge in recent times for chemists and materials scientists. Herein, two new binuclear Ln(III)-based compounds with molecular formula [Ln2L2(dbm)2(CH3OH)2]center dot xCH3OH center dot yCHCl3 2 L 2 (dbm) 2 (CH 3 OH) 2 ]center dot xCH 3 OH center dot yCHCl 3 (LnIII III = Tb (1), 1 ), x =2, y = 0; Ln III = Dy (2), 2 ), x =0, y = 2; H2L 2 L = (E)-N'(5-bromo-2-hydroxy-3-methoxybenzylidene)nicotinohydrazide; and Hdbm = 1,3-diphenyl-1,3-propanedione) have been constructed by a polydentate Schiff base ligand (H2L) 2 L) via solvothermal method. The structures, magnet behaviors, and biological activities of compounds 1 and 2 have been studied systematically. Structure studies suggest that the two Ln2 2 compounds 1 and 2 are isostructural and possess butterfly-shaped molecular structures. Magnetic studies exhibit that Dy2 2 compound 2 shows remarkable single-molecule magnet behavior under zero-field conditions with U eff / k B = 55.91 K and tau 0 0 = 4.02x10-- 7 s. Moreover, solid-state fluorescent properties research shows that the two Ln2 2 compounds display the characteristic Tb3+ 3+ and Dy3+ 3+ ions luminescence at room temperature. Furthermore, biological activities research reveal that the two Ln2 2 compounds have better antibacterial activities against four common types of bacteria ( Escherichia coli, Staphylococcus aureus, Candida albicans, and Bacillus subtilis) ) than the polydentate Schiff base ligand (H2L) 2 L) and beta-diketo salts Ln (dbm)3 center dot 2H2O 3 center dot 2H 2 O (Ln(III) = Tb III and DyIII). III ). The interaction between Ln2 2 compounds (1 1 and 2 ) and calf thymus DNA have also been studied, and the result reveal that both Tb2 2 and Dy2 2 compounds were mainly intercalated with calf thymus DNA. To our knowledge, compounds 1 and 2 are rarely reported multifunctional Ln(III)-based compounds owning single-molecule magnet behavior, fluorescent properties, and biological activities simultaneously.