Reversible single-crystal-to-single-crystal transition in Gd() metal-organic frameworks induced by heat and solvents with a significant magnetocaloric effect

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 53; no. 12; pp. 561 - 567
• Main Authors: Wang, Jin-Jin, Li, Yu, Zheng, Teng-Fei, Peng, Yan, Chen, Jing-Lin, Liu, Sui-Jun, Wen, He-Rui
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 19.03.2024
• Subjects: Aqueous solutions; Gadolinium; Magnetic induction; Magnetic relaxation; Metal-organic frameworks; Pore size; Single crystals; Solvents; Thiadiazoles
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt03867j

The design and synthesis of a Gd( iii ) metal-organic framework with the formula [Gd 4 (BTDI) 3 (DMF) 4 ] n ( JXUST-40 , H 4 BTDI = 5,5′-(benzo[ c ][1,2,5]thiadiazole-4,7-diyl)diisophthalic acid) are reported hererin. Interestingly, a reversible single-crystal-to-single-crystal transition between JXUST-40 and {[Gd 4 (BTDI) 3 (H 2 O) 4 ]·6H 2 O} n ( JXUST-40a ) was achieved under the stimulation of heat and solvents. Both JXUST-40 and JXUST-40a exhibited good stability when soaked in common solvents and aqueous solutions with pH values of 1-12. Magnetic studies showed that JXUST-40a has a larger magnetocaloric effect with -Δ S max m = 26.65 J kg −1 K −1 at 2 K and 7 T than JXUST-40 due to its larger magnetic density. Structural analyses indicated that the coordinated solvent molecules play a crucial role in the coordination environment around the Gd( iii ) ions and the change in the framework, ultimately leading to the changes in the pore size and magnetism between JXUST-40 and JXUST-40a . In addition, both isomorphic [Dy 4 (BTDI) 3 (DMF) 4 ] n ( JXUST-41 ) and {[Dy 4 (BTDI) 3 (H 2 O) 4 ]·6H 2 O} n ( JXUST-41a ) displayed slow magnetic relaxation behaviour. Triggered by heat and solvents, Gd( iii ) MOF undergo a SC-SC transition. JXUST-40a exhibits better stability and a larger magnetocaloric effect with −Δ S max m = 26.65 J kg −1 k −1 under a 7 T applied field.