A Series of High-Nuclear Gadolinium Cluster Aggregates with a Magnetocaloric Effect Constructed through Two-Component...

The serialized expansion of high-nuclear clusters usually includes the controlled variable method and changes only a single variable. However, changing both variables will greatly increase the complexity of the reaction simultaneously. Therefore, the use of a two-component regulation reaction is rare. Herein, we used a diacylhydrazone ligand (H₄L¹) with multidentate chelating coordination sites for the reaction with Gd(NO₃)₃·6H₂O under solvothermal conditions to obtain an example of 16-nucleus disc-shaped cluster 1 with a brucite structure. The overall structure of cluster 1 can be regarded as an equilateral triangle, which is formed by three (L¹)^4- ions that can be regarded as "sides" and wrap the four-layer metal center Gd(III) ions. Notably, upon simultaneous regulation of the substituent of the ligand and the coordination anion, heptanuclear gadolinium cluster 2 was obtained. Cluster 2 can be regarded as a butterfly structure, which was formed by connecting two Gd₃L² molecules that were not in the same plane and through the central Gd(III) ion as an intersection. Moreover, hexanuclear gadolinium cluster 3 was obtained by changing the ligand substituent and adding an auxiliary ligand. Cluster 3 can be regarded as a chair structure, which was composed of two molecules of diacylhydrazone ligand (L²)^4- wrapping vacant cubane shared by four vertices. This study was the first to construct a series of high-nuclear gadolinium clusters through two-component regulation manipulation. The study of the magnetocaloric effect showed that the maximum values of -ΔS_m for clusters 1-3 were 34.05, 29.04, and 24.32 J kg^-1 K^-1, respectively, when T = 2 K and ΔH = 7 T.