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The terbium-aluminum metallacrowns (MC), TbAl4Na (left image & capillary) and Tb2Al8Na2 (right image & capillary) emit green light. Tb2Al8Na2 has a quantum yield value of 43.9%, the highest value observed in the solid state to date for a TbIII MC.

A series of heterotrimetallic manganese-lanthanide-sodium dimer metallacrowns has been synthesized and characterized by single-crystal X-ray analysis: {LnNa[12-MCMn(III)N(shi)-4]}2(iph)4, where LnIII = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14), and Y (15); MC is metallacrown; shi3− is salicylhydroximate; and iph2− is isophthalate. The manganese(III) ions and shi3− ligands generate the 12-MC-4 framework with one LnIII and Na+ ion bound to each [12-MCMn(III)N(shi)-4] on opposite sides of the central MC cavity. The carboxylate groups of the isophthalate ligands bridge between the central LnIII ion and each ring MnIII ion, and the meta-arrangement of the carboxylate groups joins two LnNa[12-MCMn(III)N(shi)-4] units together to form the dimer through the LnIII ions, which reside on the interior of the molecule. The identity of the central LnIII ion slightly impacts the size the [12-MCMn(III)N(shi)-4] framework. As the crystal radius of the LnIII ion increases from LuIII (1.02 A) to LaIII (1.19 A), the 12-MC-4 framework expands to accommodate the larger LnIII ion as the MC cavity increases in size (0.53 A for LuIII to 0.58 A for LaIII) and the average cross cavity MnIII-MnIII and oxime oxygen-oxime oxygen distances also increase (MnIII-MnIII distances: 6.48 A for LuIII to 6.52 A for LaIII; Ooxime-Ooxime distances: 3.66 A for LuIII to 3.75 A for LaIII). In addition, the larger LnIII ions reside further from the MC cavity as indicated by the LnIII-oxime oxygen mean plane (OoxMP) distance. The LnIII-OoxMP distance steadily decreases from LaIII (1.7527(12) A) to LuIII (1.5575(15) A). The complex {LaNa[12-MCMn(III)N(shi)-4]}2(iph)4(DMF)6(H2O)2 is a dimer of [12-MC-4] molecules linked by four isophthalate anions

Two series of aluminum-lanthanide-sodium 12-metallacrown-4 compounds have been synthesized and characterized by single-crystal X-ray analysis. For the individual LnNa(ben)4[12-MCAl(III)N(shi)-4] molecules, where LnIII = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), Yb (8), Lu (9), and Y (10), ben− is benzoate, MC is metallacrown, and shi3− is salicylhydroximate, two independent molecules are present in each unit cell. The aluminum(III) ions and shi3− ligands comprise the MC framework, while the LnIII and Na+ ions bind opposite of each other across the central MC cavity. The benzoate anions serve to tether the LnIII ion to the MC framework. When benzoate is replaced with the dicarboxylate anion isophthalate (iph2−), two [12-MCAl(III)N(shi)-4] units are connected to form a dimer of MCs: {LnNa[12-MCAl(III)N(shi)-4]}2(iph)4, where LnIII = Eu (11), Gd (12), Tb (13), Dy (14), Ho (15), Ho (16), Er (17), Yb (18), and Lu (19). As in 1–10, the aluminum(III) ions and shi3− ligands produce the MC frameworks, and one LnIII ion binds to each central MC cavity. However, there are two binding modes for the sodium ions. For 12–15 and 18, the sodium ions bind to the central MC cavity opposite of the LnIII ions as in 1–10. For 11, 16, 17, and 19, the sodium ions bind to the side of the MC framework by bonding to the phenolate and carboxylate oxygen atoms of two shi3− ligands and to the carboxylate oxygen atom of an iph2− ligand. In these structures, the MC cavity is vacant opposite of the LnIII ions. The substitution of isophthalate for benzoate does not significantly alter the [12-MCAl(III)N(shi)-4] framework as the size of the central MC cavity is not significantly different between analogous lanthanide individual and dimer MCs. However, the identity of the central LnIII ion does determine how close the LnIII ion can approach the mean plane of the oxime oxygen atoms (OoxMP) of the MC cavity. As the ion radius of the central LnIII ion decreases, the LnIII ion is able to more closely approach the OoxMP. For the individual MCs 1–10, the EuIII of 1 is the farthest away from the OoxMP (1.55 A) and this value steadily decreases to 1.44 A for the LuIII ion of 9. This same trend is true for the dimer MCs as the EuIII ion of 11 is 1.45 A from the OoxMP and the LuIII ion of 19 is 1.36 A from the OoxMP. Though the location of the sodium ions in the dimer MCs does influence the LnIII-OoxMP distance as the absence of the sodium ion in the MC cavity allows the LnIII ion to approach the MC cavity even closer. In 15 a sodium ion is opposite the HoIII ion and the HoIII-OoxMP distance is 1.47 A, while in 16 the sodium ion is bound to the side of the MC and the HoIII-OoxMP distance is 1.40 A. The complex GdNa[12-MCAl(III)N(shi)-4]}2(iph)4(DMF)2(H2O)8 is a dimer of [12-MC-4] molecules linked by four isophthalate anions.