Self-assembly of octanuclear Ln(III)-based clusters: their large magnetocaloric effects and highly efficient conversion of CO2

Authors：Wang, Wen-Min; Xin, Xiao-Yan; Qiao, Na; Wu, Zhi-Lei^*; Li, Ling; Zou, Ji-Yong^*

Source：Dalton Transactions, 2022, 51(36): 13957-13969.

DOI：10.1039/d2dt01892f

• MOLECULE-MAGNET BEHAVIOR
• LANTHANIDE(III) DINUCLEAR COMPLEXES
• TITANIUM OXO CLUSTERS
• CHEMICAL FIXATION
• DY-3 TRIANGLES
• SCHIFF-BASE
• FLUORESCENCE PROPERTIES
• RELAXATION DYNAMICS
• ORGANIC FRAMEWORKS
• SLOW RELAXATION

The design and construction of high-nuclear lanthanide clusters with fascinating topology and functional properties have been an active area of research, however, the development of an effective approach for obtaining high-nuclear lanthanide clusters with multifunctional properties is still extremely difficult. Up to now, a systematic approach for guiding the further expansion of Ln(III)-based clusters showing good functional properties is lacking. Herein, we design and synthesize a polydentate Schiff base ligand (HL), which reacts with beta-diketonate salts Ln(acac)(3)center dot 2H(2)O, and a series of Ln(8) clusters [Ln(8)(acac)(6)(L)(2)(mu(3)-O)(6)(mu(2)-C2H5O)(4)(mu(2)-Hacac)(2)]center dot 2CH(3)CN (Ln(III) = Gd (1), Dy (2), and Ho (3); HL = pyridine-2-carboxylic acid (5-hydroxymethyl-furan-2-ylmethylene)-hydrazide, Hacac = acetylacetone) have been successfully synthesized. Single-crystal X-ray diffraction studies reveal that clusters 1-3 are isostructural and can be viewed as a Ln(8) core bridged by eighteen mu(2)-O atoms, six mu(3)-O atoms and two mu(4)-O atoms. Magnetic studies show that cluster 1-Gd-8 displays a large magnetocaloric effect with -Delta S-m = 46.14 J kg(-1) K-1 (T = 2.0 K and Delta H = 7.0 T); cluster 2-Dy-8 exhibits single-molecule magnet behavior under zero-field conditions. It is worth mentioning that the -Delta S-m of cluster 1-Gd-8 is larger than that of most reported polynuclear Gd(III)-based clusters; the 2-Dy-8 cluster is one of the rare polynuclear Ln(n) SMMs (n >= 8) under zero dc field. Importantly, these Ln(III)-based clusters (1-3) can catalyze the cycloaddition of CO2 with epoxides with high efficiency under mild conditions; and cluster 1-Gd-8 as a catalyst could be reused at least three times without obvious loss of catalytic performance.

• Institution
  南开大学; 天津大学