Lanthanide Contraction in Action: Structural Variations in 13 Lanthanide(III) Thiophene-2,5-dicarboxylate Coordination Polymers (Ln = La–Lu, Except Pm and Tm) Featuring Magnetocaloric Effect, Slow Magnetic Relaxation, and Luminescence-Lifetime-based Thermometry

Abstract

Thirteen new three-dimensional lanthanide­(III)-2,5-thiophenedicarboxylate coordination polymers (Ln-CPs) with general formulas of [Ln2(2,5-TDA)3(DMA)2(H2O)] n (Ln-CPs 1–4) and [Ln2(2,5-TDA)3(DMA)2] n (Ln-CPs 5–13) (where 2,5-TDA2– = 2,5-thiophedicarboxylate dianion, DMA = N,N′-dimethylacetamide, and Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Yb (12) Lu (13)) have been synthesized solvothermally under two different temperature conditions in a DMA–H2O mixed solvent system. A structural analysis discloses that the four Ln-CPs 1–4 crystallize in the orthorhombic space group Pna21, whereas the eight Ln-CPs 5–8 and 10–13 crystallize in the triclinic P̅1 space group and Ln-CP 9 (Dy) adopts the monoclinic P2/c space group. The distinct crystal structures and coordination features indicate that lanthanide contraction, ancillary DMA molecules, and different coordination modes identified for 2,5-TDA2– play deciding roles in the self-assembly of Ln-CPs 1–13. The Ln­(III) centers in compounds 1–13 exhibit three different coordination numbers, 9 (only 1; around La1), 8 (1–8 and 10–12), and 7 (4, 8, 9 and 11–13) with monocapped-square-antiprismatic, bicapped-trigonal-prismatic, and monocapped-trigonal-prismatic geometries, respectively. The title compounds display distinct 3D coordination frameworks with dinuclear (La2O15; for 1 and Ln2O14; for 2–4) SBUs and tetranuclear [Ln4O28] SBUs (for compounds 5–13). Variable-temperature magnetic susceptibility measurements were investigated for Ln-CPs 7–11 with an applied dc field of 1 kOe. The weak antiferromagnetic interaction and small ligand/metal mass ratio make Ln-CP 7 (Gd) a good candidate for low-temperature magnetic refrigeration with an impressive −ΔS m max = 31.0 J kg–1 K–1 (63.6 mJ cm–3 K–1) at T = 2 K and ΔH = 7 T. Furthermore, the frequency and temperature dependences of the alternating current (ac) susceptibilities have been studied to explore the magnetic dynamics of Ln-CPs 8–10. Importantly, for compound 9 (Dy), the χ′m and χ″m curves and Cole–Cole plots at 2–6 K suggest the existence of slow magnetic relaxation behavior. Luminescence thermometry studies have been performed at 298–373 K for Ln-CPs 6 and 8. The Eu analogue (6) features a weak temperature dependence of luminescence lifetime (relative sensitivities of 0.43% K–1 and 0.34% K–1 at 298 and 373 K, respectively), whereas the Tb analogue (8) is a good lifetime-based luminescent thermometer with a constant relative sensitivity value of 1.35% K–1 in the investigated temperature range.

Lanthanide-Aromatic Iminodiacetate Frameworks with Helical Tubes: Structure, Properties, and Low-Temperature Heat Capacity

“…For decades, lanthanide-based coordination polymers (Ln-CPs) as a new type of organic–inorganic hybrid porous materials have attracted a great deal of research interest. Due to their functional properties, versatile applications in different fields have been explored such as gas adsorption and separation, − magnetic materials, − molecular recognition − and detection, dye enrichment and separation, , and so on. Among them, lanthanide complexes with luminescent properties have been of substantial importance in many applications such as biological imaging, sensing, analysis optical data transfer, and lighting devices. − Although there is a possibility of the luminescence of Ln 3+ from intraconfigurational f–f transitions, in the case of irradiation with ultraviolet (UV) radiation, some luminescence in the visible or near-infrared spectral regions can be observed.…”

Gd(iii)-Based inorganic polymers, metal–organic frameworks and coordination polymers for magnetic refrigeration

“…In 2020, a new family of 3D Gd( iii )-2,5-thiophenedicarboxylate CPs with the formulae [Gd(2,5-TDA) 3 (DMA) 2 ] n ( 34 ) (H 2 TDA = 2,5-thiophenedicarboxylic acid) were solvothermally synthesized under 165 °C in a DMA–H 2 O mixed solvent system by Sheikh et al 69 Covalent interactions in the 3D polymeric architecture were reinforced and stabilized by hydrogen bonds between various donor and acceptor pairs within the structural motifs of 34 to form a 3D supramolecular framework. The −Δ S m,max value of this complex was 31.00 J kg −1 K −1 at 2 K and Δ H = 7 T, which was larger than for most magnetic refrigeration materials.…”

Microwave-assisted synthesis of anhydrous lanthanide-based coordination polymers built upon benzene-1,2,4,5-tetracarboxylic acid

“…Lanthanide coordination polymers is a fascinating class of materials which is widely investigated due to their potential applications in gas storage [1][2][3][4][5][6] , catalysis 7 , magnetism [8][9][10][11][12] or luminescence [13][14][15][16][17] . Most of them are built with benzoic multicarboxylate ligands which are versatile building blocks to obtain various coordination polymers due to their variety of bridging abilities 2,[18][19][20] .…”