title: Solvent triggered structural diversity of triple-stranded helicates: single molecular magnets.
abstract: Multiple-stranded helicates are of interest in respect of their simplicity in geometry and significance in biology and materials. Bis-β-diketones have shown their advantage in terms of structure and geometry in the construction of multiple-stranded helicates, but further studies on their properties are limited due to their poor crystallization. In this study, solvents are found to play a decisive role in the crystallization of triple-stranded helicates. [Dy2(BTB)3(H2O)4] is used as a precursor to solvent-dependently crystallize three complexes [Dy2(BTB)3(CH3OH)4]·3CH3OH (1), [Dy2(BTB)3(DME)2] (2) and [Dy2(BTB)3(DOA)(H2O)2]·4.5DOA (3) (BTB = 3,3'-bis(4,4,4-trifluoro-1,3-dioxobutyl)biphenyl), where the key structural motif of the triple-stranded helicate, [Dy2(BTB)3], is retained. Four methanol molecules are found to ligate to Dy(3+) ions in 1, while each Dy(3+) ion is chelated by one DME molecule in 2. Interestingly, it is observed that 1,4-dioxane as a bridge ligates to two adjacent Dy(3+) ions, giving rise to the formation of a 1D chain structure. Magnetic measurement shows that 1 and 2 display slow magnetic relaxation under zero dc field, while single molecular magnet behavior is obtained for 3 under an applied dc field of 2000 Oe.
authors.affiliation: Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, P.R. China. jehugu@gmail.com yanpf@vip.sina.com.
authors.forename: Hongfeng
authors.initials: H
authors.lastname: Li
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.forename: Wenbin
authors.initials: W
authors.lastname: Sun
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Pengfei
authors.initials: P
authors.lastname: Yan