Lanthanide metal-organic frameworks containing ethylene diamine tetraacetic acid exhibiting large magnetocaloric effect and interesting luminescence properties

• Published in: Journal of rare earths 2024-05
• Main Authors: Wang, Qin, Wu, Qiongru, Xu, Lingtong, Yu, Yating, Wang, Jilei, Yan, Pinfang, Bai, Xu, Xu, Yan
• Format: Article
• Language: English
• Subjects: 3D complex; Ln2; Luminescence; Magnetocaloric effect; Rare earths
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/j.jre.2024.05.013

The assembly of the three-dimensional (3D) lanthanide complexes, aiming at obtaining large magnetocaloric effects, encounters a substantial challenge. In this study, we successfully isolated a novel series of Ln-exclusive 3D complexes, formulated as {[Ln2(EDTA)(C2O4)(H2O)2]}n (abbreviated as Ln2, Ln = GdIII (1), EuIII (2), SmIII (3), H4EDTA = ethylene diamine tetraacetic acid; H2C2O4 = oxalic acid). Crystallographic study exhibits that complex 1 features a cute snail-shaped Gd2 unit. Adjacent Gd2 units are aggregated by hexadentate EDTA4– and C2O42– ligands, further constructing a charming three-dimensional metal-organic framework with interesting parallelogram-shaped layers. Notably, all coordinated EDTA4– ligands and lightweight C2O42– groups contribute to building a densely packed metal-organic framework, endowing complex 1 with remarkable magnetocaloric effect (–ΔSmmax = 42.5 J/(kg·K) at 2.5 K and ΔH = 7.0 T). Additionally, complexes 2 and 3 exhibit outstanding solid-state luminescent properties with lifetimes of 438.22 and 4.13 μs, and quantum yields (QY) of 7.03% and 15.46%, respectively. Three charming three-dimensional (3D) metal-organic frameworks with captivating parallelogram-shaped layers were successfully synthesized. All coordinated EDTA4– ligands and lightweight C2O42– anions endow complex 1 with a large magnetic entropy change, and outstanding solid-state luminescent properties. [Display omitted] •Three novel Ln2 complexes were successfully synthesized.•A charming three-dimensional (3D) metal-organic framework with captivating parallelogram-shaped layers.•A 3D dense framework endows complex 1 with a large large -ΔSm values of 42.5 J kg-1 K-1 at 2.5 K for 7.0 T.