In situ synthesized homochiral dysprosium-oxo clusters with threonine Schiff bases

Abstract

Chiral high-nuclearity lanthanide (4f) clusters have shown fantastic properties in various fields. However, their synthesis is still of great challenge. Herein, we report two pairs of enantiomers of high-nuclearity Dy-oxo clusters synthesized through in situ strategy. They are [Dy18(R/SHftp)4 (R/SH2btp)4(μ2-OH)8(μ3-OH)20(μ6-O)(NO3)4(μ-H2O)8]·[solvents] (1R and 1S) and [Dy9(R/SHftp)2 (R/SH2btp)2(OAc)6(μ3-OH)10(H2O)6](OAc)·[solvents] (2R and 2S), where R/SHftp2− and R/SH2btp3− represent in situ formed 2-formyl-6-[N-(threonine)iminomethyl]-4-methylphenol and 2,6-bis[N-(threonine)iminomethyl]-4-methylphenol anions, respectively. These in situ formed clusters were endowed with not only homochirality via introducing R/SHftp2− and R/SH2btp3− ligands, but also rich oxo-bridges by controlling the hydrolysis of DyIII ions. Different anions from DyIII salts further induced structural variation between two sets of clusters. 1R and 1S feature an unprecedent four-blade propeller shaped {Dy18} core, whose centered octahedral {Dy6} unit are surrounded by four triangular {Dy3} units. Strikingly, they represent the second largest chiral 4f cluster species so far. 2R and 2S display a sandglass-like {Dy9} skeleton that consist of two square pyramid {Dy5} units sharing a DyIII vertex. Magnetic investigation revealed possible antiferromagnetic interactions between the DyIII centers in these clusters.