Sandglass-like Ln<sub>9</sub> Nanoclusters with Magnetocaloric\nEffect and Lanthanide-Centered Luminescence

It is a challenging work to construct high-nuclear lanthanide\nnanoclusters\nwith desirable magnetocaloric effects. To this end, a series of Ln<sub>9</sub> nanoclusters with sandglass-like topological structures have\nbeen successfully synthesized under solvothermal conditions by using\ntwo different alcoholamine ligands and lanthanide (Ln<sup>III</sup>) salts, with the molecular formula [Ln<sub>9</sub>(L<sup>1</sup>)<sub>4</sub>(NO<sub>3</sub>)<sub>12</sub>(μ<sub>3</sub>-OH)<sub>8</sub>(μ<sub>4</sub>-OH)<sub>2</sub>(CH<sub>3</sub>CH<sub>2</sub>OH)<sub>4</sub>]·4.5CH<sub>3</sub>CH<sub>2</sub>OH·3Et<sub>3</sub>NH (Ln<sup>III</sup> = Gd (<b>1-Gd</b>), Eu (<b>1-Eu</b>), Tb (<b>1-Tb</b>)) and [Ln<sub>9</sub>(L<sup>2</sup>)<sub>8</sub>(NO<sub>3</sub>)<sub>8</sub>(μ<sub>3</sub>-OH)<sub>8</sub>(μ<sub>4</sub>-OH)<sub>2</sub>]·NO<sub>3</sub> (Ln<sup>III</sup> = Gd (<b>2-Gd</b>), Eu (<b>2-Eu</b>), Tb (<b>2-Tb</b>)) (H<sub>2</sub>L<sup>1</sup> = <i>N</i>-methyldiethanolamine\nand HL<sup>2</sup> = 2-(2-aminoethoxy)ethanol). It is worth noting\nthat both <b>1-Gd</b> and <b>2-Gd</b> exhibit intramolecular\nantiferromagnetic interactions and show typical magnetocaloric effect\nbehavior. At a magnetic field strength of 7 T and a temperature of\n3 K, the values of the −Δ<i>S</i><sub>m</sub><sup>max</sup> are 33.65 J kg<sup>–1</sup> K<sup>–1</sup> for <b>1-Gd</b> and 25.22 J kg<sup>–1</sup> K<sup>–1</sup> for <b>2-Gd</b>. In addition, <b>1-Eu</b>, <b>1-Tb</b>, <b>2-Eu</b>, and <b>2-Tb</b> exhibit the characteristic\nluminescence of Eu<sup>III</sup> and Tb<sup>III</sup> ions, respectively.\nFor <b>1-Tb</b>, tunable emission from green to red was achieved\nby adjusting the doping ratio of lanthanide ions to obtain heterometallic\nclusters <b>Tb</b><sub><i>x</i></sub><b>Eu</b><sub><b>9‑x</b></sub>, offering the potential for high-fidelity\noptical barcode applications.