Inorganic Chemistry, Vol.58, No.13, 8494-8499, 2019
High-Nuclearity Chiral 3d-4f Heterometallic Clusters Ln(6)Cu(24) and Ln(6)Cu(12)
Based on the anion template and chiral ligand inducting role, two series of f high-nuclearity 3d-4f heterometallic clusters with formulas [NO3@Ln(6)Cu(24)(mu(3) - OH)(30)(mu(2)-OH )(3)(OAc)(6)(R/S-L)(12)(H2O)(24)] (NO3)(14)center dot x(H2O) (Ln = Dy, x = 30 for 1a(R-L) and 1b(S-L); Ln = Tb, x = 40 for 2a(R-L) and 2b(S-L)) and (Et3NH)(4) [Ln(6)Cu(12)(mu(3)-OH)(14)(mu(2)-Cl)(6)Cl-12(R/S-L)(12)]Cl-2 center dot x(H2O) (Ln = Dy, x = 28 for 3a (R-L) and 3b (S-L); Ln = Tb, x = 33 for 4a (R-L) and 4b (S-L); HL = (R/S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid), have been synthesized and characterized. Structural analysis reveals that the metal skeleton of compounds 1 and 2 display a Ln(6)Cu(12) octahedral inner core encapsulated by six outer Cu-2 units. In the Ln(6)Cu(12) octahedron, 6 Ln(3+) ions located at the six vertices and 12 inner Cu2+ ions located at the 12 edges of octahedron, and one NO3- locates in the center of the octahedron. The metal core of compounds 3 and 4 can be viewed as a Ln(6) octahedron encapsulated by six Cu-2 units. It is interesting that the different inorganic anions involved in the reaction result in the difference in the structures of 1 to 2 and 3 to 4. Circular dichroism spectra of 1-4 display obvious mirror symmetry effect at 600-800 nm of d-d transition of Cu2+, suggesting that the chirality transferred from chiral R- and S-ligand to Cu2+ ions in this system. Notably, the CD peak at the Cu2+ d-d transition position of Ln(6)Cu(12) cluster is obviously blue-shifted compared with that of Ln(6)Cu(12) due to the different coordinated environments of Cu2+. Magnetic studies indicate that la and 2a show weak ferromagnetic interactions, while 3a and 4a display antiferromagnetic interactions.