Abstract
The precise syntheses of transition–rare-earth metal clusters with
desired structures remain a great challenge. Herein, by utilizing
SO4 2– anion released by in-situ
decomposition of sodium dodecyl sulfate (SDS) as a template, a series of
novel high-nuclear ity 3d-4f clusters, formulated as
[Ni24Pr22(μ3-OH)31(pida)24(SO4)4
(NO3)9(CH3
COO)3]·Br4·(NO3)11·
16H 2O·25CH3OH (1,
H2pida = N-phenyliminodiacetic acid),
[Ni24Nd22(μ3-OH)31(pida)24(SO4)4(NO3)9(CH3COO)3
]·Br4·(NO3)11·14H2O·
24CH3OH·(2)·and
[Ni24Gd22
(μ3-OH)36(bida)24(SO4)7(NO3)3(CH3
COO) 3]·(SO4)·Br4
·(NO3)4·31H2O
32CH3OH (3, H 2 bida =
N-benzyliminodiacetic acid), have been successfully isolated. X-ray
crystal structure analyses reveal that all the cationic
{Ni24 RE22}cores in 1–3 possess a
ball-like structure with C3v symmetry, and can be viewed as consisting
of an inner {RE22} core and an outer
{Ni24} shell. From 1 and 2 to 3, due to the lanthanide
contraction effect, the coordina -tion numbers for rare-earth metal
centers in {RE22} are different, resulting in
differ-ent number of SO42– and
NO3– anions to support and stabilize
the skeleton structures. Meanwhile, the magnetic properties of
com-plexes 1–3 were also studied. The result revealed that complexes
1–3 show antiferromagnetic /ferrimagnetic interactions, and 3 ex-hibits
magneto-caloric effect at ultralow temperatures with a maximum –ΔSm
(magnetic entropy change) value of 33.03 J·kg−1
·K−1 at 3.0 K and 7 T.
