Crystal Structure, Fluorescence Properties, and Biological Activity of Three Butterfly-shaped Ln4 Compounds

Three tetranuclear lantharide-based compounds: [Ln(4)(dbm)(4)(L)(6)(mu(3)-OH)(2)]center dot CH3CN (Ln(III) = Eu (1), Tb (2) and Ho (3), HL = 5-(4-methylbenzylidene-8- hydroxyquinoline, dbm(-) = dibenzoylmethane) were fabricated and structurally characterized. X-ray diffraction studies reveal that all the compounds 1-3 belong to monoclinic crystal system with space group P2(1)/n, and compounds 1-3 are isostructural and possess a rhombic Ln(2)O(2) core. The solid-state luminescence property measurements indicated that the compounds 1 and 2 displayed the characteristic lanthanide luminescence at room temperature. Furthermore, biological activity researches revealed that the compounds 1-3 had better antibacterial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Candida albicans than the ligand HL and Ln(dbm)(3)center dot 2H(2)O (Ln = Eu, Tb, and Ho). The interaction between compounds 1-3 and calf thymus DNA was studied and the results revealed that the compounds were mainly intercalated with calf thymus DNA.