Construction of a High Nuclear Gadolinium Cluster with Enhanced Magnetocaloric Effect through Structural Transition

Starting from a dinuclear complex {Gd2(L)2(NO3)4(H2O)2}·2­(CH3CN) (1) based on 2,6-dimethoxyphenol (HL), a
nonanuclear cluster {Gd9(L)4(μ4-OH)2(μ3-OH)8(μ2-OCH3)4(NO3)8 (H2O)8}­(OH)·2H2O (2)
was obtained via modulating the amount of the ligand and base. Both
of them have been structurally and magnetically characterized. Complex 1 decorates the Gd2 core bridged by double μ2-phenoxyl oxygen atoms and coordinated neutral CH3CN molecules, while 2 features the Gd9 core
with a sandglass-like topology. Magnetic investigations reveal that
the weaker antiferromagnetic interactions between adjacent metal ions
exist in complex 2 than in 1, which is in
agreement with the theoretical results. Meanwhile, the magnetocaloric
effect with a maximum −ΔSm value changes from 27.32 to 40.60 J kg–1 K–1 at 2 K and 7 T.