Two pairs of chiral lanthanide–oxo clusters Ln 14 induced by amino acid derivatives

• Published in: CrystEngComm 2021-10, Vol.23 (39), p.6923-6929
• Main Authors: Lu, Tian-Qi, Yin, Jia-Jia, Chen, Cheng, Shi, Hai-Yan, Zheng, Jun, Liu, Zhengjie, Fang, Xiaolong, Zheng, Xiu-Ying
• Format: Article
• Language: English
• ISSN: 1466-8033; 1466-8033
• DOI: 10.1039/D1CE00948F

Two pairs of pure enantiomers of high-nuclearity chiral lanthanide–oxo clusters with the formulas [Y 14 (L) 16 ( μ 3 -OH) 16 (H 2 O) 20 ]·(ClO 4 ) 10 · x H 2 O ( x ≈ 55; L = l -L − for l -Y 14 ; L = d -L − for d -Y 14 ) and [Dy 14 (L) 16 ( μ 3 -OH) 16 (H 2 O) 20 ]·(ClO 4 ) 10 · x H 2 O ( x ≈ 67; L = l -L − for l -Dy 14 ; L = d -L − for d -Dy 14 ) were prepared in the presence of chiral ligands N -acetyl- l -alanine ( l -HL) and N -acetyl- d -alanine ( d -HL). Structural analysis showed that four cubane-like units as building blocks sharing vertices formed the lanthanide–oxo cluster unit {(ClO 4 ) 2 @[Y 12 ( μ 3 -OH) 16 ]} 18+ with two ClO 4 − as anion templates. The remaining Y 3+ ions were connected to the opposite position of {(ClO 4 ) 2 @[Y 12 ( μ 3 -OH) 16 ]} 18+ through four l -L − , respectively. High-resolution electrospray ionization mass spectrometry (HRESI-MS) captured the signals of the cluster fragment {Y 12 (OH) 16− x (O) x } ( x = 4, 5, 6, 7, 8) and the unbroken dimer of {Y 12 ( l -L) 12 (OH) 16− x (O) x } 2 ( x = 4, 5, 12) from l -Y 14 in a mixed solution of methanol and dichloromethane, suggesting that {Ln 12 (OH) 16− x (O) x } is a stable cluster unit that could be further assembled into higher-nuclearity lanthanide–oxo clusters in solution. The solid-state circular dichroism (CD) spectra of compounds l -Y 14 / d -Y 14 and l -Dy 14 / d -Dy 14 displayed mirror symmetry effects in the range of 220–250 nm. The study of magnetic properties showed that l -Dy 14 had a weak antiferromagnetic interaction and displayed SMM-like behavior in the absence of a dc field.