pH-induced Dy₄ and Dy₁₀ cluster-based 1D chains with different magnetic relaxation features.

Two novel tetra- and deca-nuclear dysprosium compounds, namely, [Dy4(μ3-OH)2(L)10(bipy)2(H2O)2]n (1) and {[Dy10(μ3-OH)8(L)22(bipy)2(H2O)2]·5H2O}n (2) (L = 3-fluoro-4-(trifluoromethyl)benzoic acid; bipy = 2,2'-bipyridine), have been successfully obtained by hydrothermal reaction at different pH values. The solid state structures of 1 and 2 were established by the single crystal X-ray diffraction technique, and both of them exhibit complicated 1D chains with [Dy4] (1) and [Dy10] (2) cluster units, respectively. Adjacent [Dy4] in 1 and [Dy10] in 2 are connected by two bridging carboxylate groups in the η(1):η(1):μ2 mode. Magnetic studies reveal that they exhibit different magnetic relaxation behaviors with the energy barrier of 23.6 K for 1 and 3.2 K for 2. Interestingly, the large divergence in both the structures and magnetic properties for 1 and 2 only originated from the different pH values in preparing them.