A series of planar tetranuclear lanthanide complexes: axial ligand modulated magnetic dynamics in Dy 4 species

• Published in: RSC advances Vol. 7; no. 87; pp. 55523 - 55535
• Main Authors: Zhang, Ya-Xin, Li, Meng, Liu, Bi-Ying, Wu, Zhi-Lei, Wei, Hai-Ying, Wang, Wen-Min
• Format: Journal Article
• Language: English
• Published: 2017
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C7RA11750G

Ten new lanthanide compounds were successfully obtained based on an 8-hydroxyquinoline Schiff base derivative and β-diketonates with different substituent groups, namely, [Ln 4 (μ 3 -OH) 2 L 6 (acac) 4 ]·2.5CH 3 CN (Ln = Gd ( 1 ), Tb ( 2 ), Dy ( 3 ), Ho ( 4 ) and Yb ( 5 ); HL = 5-(4-methoxybenzylidene)-8-hydroxylquinoline; Hacac = acetylacetone), [Ln 4 (μ 3 -OH) 2 L 6 (tmhd) 4 ]· x CH 3 CN· y CH 3 CH 2 OH (Ln = Eu ( 6 ), Gd ( 7 ), and Tb ( 8 ), x = 1, y = 1; Ln = Dy ( 9 ), x = 2, y = 0; Htmhd = 2,2,6,6-tetramethyl-3,5-heptanedione) and [Dy 4 (μ 3 -OH) 2 L 6 (beac) 4 ]·CH 3 CN ( 10 ) (Hbeac = 1-benzoylacetone). Single crystal X-ray diffraction revealed that compounds 1–10 all contain planar tetranuclear lanthanide centers with a similar butterfly-shape arrangement, and each lanthanide ion is located in a distorted bicapped trigonal prism coordination sphere. 1 ·Gd and 7 ·Gd exhibit magnetic refrigeration behavior with the maximum values of −Δ S m being 19.39(2) and 16.21(3) J K −1 kg −1 , respectively. Additionally, the effects of steric-hindrance on the magnetic anisotropy of the Dy 3+ centers in 3 ·Dy, 9 ·Dy and 10 ·Dy were observed through comparative studies on their magnetic behaviors, which showed different SMM behaviors with energy barriers of 99.29(3) K for 3 ·Dy, 64.56(4) K for 9 ·Dy and 61.05(0) K for 10 ·Dy.