A series of dysprosium clusters assembled by a substitution effect-driven out-to-in growth mechanism

Although the design and synthesis of high-nuclear lanthanide clusters with specific shapes and functions have been an active area of research, effective experience and rules to guide further systematic expansion of lanthanide clusters with different connections are lacking. Herein, we adjusted the steric hindrance effects on the substituents of diacylhydrazone ligands (H 4 L 1 , N ′ 2 , N ′ 9 -bis(( E )-2-hydroxybenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide; H 4 L 2 , N ′ 2 , N ′ 9 -bis(( E )-2-hydroxy-3-methylbenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide; H 4 L 3 , N ′ 2 , N ′ 9 -bis(( E )-3-( tert -butyl)-2-hydroxybenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide) and reacted them with Dy(NO 3 ) 3 ·6H 2 O under solvothermal conditions to obtain three dysprosium clusters ( 1-3 ) with different shapes. The molecular formulas of the abovementioned clusters are [Dy 16 (L 1 ) 3 (μ 3 -OH) 25 (NO 3 ) 11 (H 2 O) 10 ]·4CH 3 CN·8CH 3 OH, [Dy 10 (L 2 ) 4 (μ 2 -OH) 2 (μ 3 -O) 4 (NO 3 ) 4 (CH 3 CN) 2 (CH 3 OH) 4 (H 2 O) 8 ]·CH 3 OH·8H 2 O, and [Dy 5 (L 3 ) 2 (μ 2 -CH 3 O)(μ 2 -OH) 2 (μ 4 -O)(NO 3 ) 2 (CH 3 OH) 2 ]·6CH 3 OH·2CH 3 CN. Cluster 1 with a brucite-like planar structure crystallizes in the P 2 1 / n space group of the monoclinic system. The Dy( iii ) ions in the cluster 1 structure are bridged by μ 3 -OH − to form a plane triangle shape. In addition, the structure of cluster 1 contains three layers of Dy( iii ) ions (1 + 6 + 9) with different coordination environments. Cluster 2 crystallizes in the P 1&cmb.macr; space group of the triclinic system. The cluster core in cluster 2 is composed of two molecules of missing cubane Dy 4 O 6 and two Dy( iii ) ions. The ligand (L 2 ) 4− adopts two coordination modes (μ 3 -η 1 :η 1 :η 2 :η 1 :η 1 :η 2 :η 1 :η 1 and μ 5 -η 2 :η 1 :η 1 :η 1 :η 1 :η 1 :η 1 :η 1 :η 1 :η 2 ) to chelate Dy( iii ) ions. In addition, Dy( iii ) ions in Dy 4 O 6 are connected by μ 2 -OH − and μ 3 -OH − . Two molecules of planar Dy 3 L 3 intersect to form cluster 3 , and it crystallizes in the I 2/ a space group of the monoclinic system. The analysis of the structure of clusters 1-3 shows that they are formed by a stepwise assembly process from outside to inside. To the best of our knowledge, a very small number of examples have reported that a series of differently connected dysprosium clusters were obtained through the regulation of substitution effects. Notably, we are the first to propose the out-to-in growth mechanism of