Syntheses, structures, and properties of high-nuclear 3d-4f clusters with amino acid as ligand:: {Gd6Cu24}, {Tb6Cu26}, and {(Ln6Cu24)2Cu} (Ln = Sm, Gd)

Four novel high-nuclear 3d-4f heterometallic clusters were obtained through the self-assembly of Ln(III), Cu-II, and amino acid ligands (2-methylalanine (mAla), glycine (Gly), and L-proline ( Pro), respectively). The metal skeleton of cluster 1, [Gd6Cu24(mu(3)-OH)(30)(mAla)(16)(ClO4)(H2O)(22)]center dot(ClO4)(17)center dot(OH)(2)center dot(H2O)(20), may be described as a huge {Gd6Cu12} octahedron connected with 12 additional Cu-II ions. The structure of cluster 2, Na-4[Tb6Cu26(mu(3)-OH)(30)(Gly)(18)( ClO4)(H2O)(22)]center dot(ClO4)(25)center dot(H2O)(42), may be described as a {Tb6Cu24} main structure connected with two [Cu(Gly)(H2O)(2)](+) groups. Compounds {[Ln(6)Cu(24)(mu(3)-OH)(30)(Pro)(12)(Ac)(6)(ClO4)(H2O)(13)](2)Cu(Pro)(2)}center dot(ClO4)(18)center dot(OH)(16)center dot(H2O)(55) (Ln = Sm (3), Gd (4)) are 61-nuclear clusters, which represent the largest known 3d-4f clusters so far, the structure can be described as two {Ln(6)Cu(24)} octahedral units connected by a trans-Cu(proline)(2) bridge. The electrical conductivity measurements reveal that they are temperature-sensitive semiconductors. The magnetic susceptibility measurements display that compound 4 is ferromagnetic.