Abstract
Reaction of Gd(OAc)(3)·4H(2)O, salicylaldehyde and CH(3)ONa in MeCN/MeOH affords [Gd(12)Na(6)(OAc)(25)(HCO(2))(5)(CO(3))(6)(H(2)O)(12)]·9H(2)O.0.5MeCN (1·9H(2)O.0.5MeCN), whose structure describes a quadruple-wheel consisting of two {Na(3)} and two {Gd(6)} rings. The magnetic properties of 1 reveal very weak antiferromagnetic interactions between the Gd(III) ions, which give rise to a record magnetocaloric effect at low applied magnetic fields and low temperatures. The magnetic entropy change reaches -ΔS(m)= 29.3 J kg(-1) K(-1) for full demagnetization from B = 1 T at T = 0.5 K.