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Four two-dimensional heterometallic Cu–Ln coordination polymers based on the 2-methylenesuccinic acid (H2MSA) ligand, {[Ln2Cu(MSA)4(H2O)6]·2H2O}n(Ln = La (1); Gd (2); Tb (3); Dy (4)), have been obtained under hydrothermal conditions. Complexes 1–4 bear a feature of one-dimensional [Ln2Cu] chains linked by 2-methylenesuccinate (MSA2−) bridges to form a 2D layer structure. Magnetic studies suggest the presence of weak antiferromagnetic Gd…Gd coupling and weak ferromagnetic Cu…Gd coupling in the 1D [Gd2Cu] chain unit of 2. The magnetic entropy change (−ΔSm) reached 36.05(1) J K−1 kg−1 for 2, making it an attractive refrigerant for low-temperature applications. [ABSTRACT FROM AUTHOR]

One two‐dimensional (2D) GdIII coordination polymer based on isonicotinic acid N‐oxide (HINNO), {[Gd(INNO)2(HCOO)] ⋅ 2H2O}n (1), was successfully synthesized and characterized. Magnetic studies reveal the presence of weak antiferromagnetic couplings between adjacent GdIII ions in the 1D chain units of 1 and large cryogenic magnetocaloric effect with maximum −ΔSm of 31.84 J kg−1 K−1 at T=2 K and ΔH=7 T. [ABSTRACT FROM AUTHOR]

Four co-edge rhomboid [Ln 4 (μ 3 -OH) 2 ]-based 1D chainlike LnCPs were synthesized based on orotic acid. The Gd-containing complex displays a large MCE of −Δ S m max = 37.11 J kg−1 K−1, and the Eu- and Tb-based polymers exhibit characteristic Ln(III) luminescence. [Display omitted] • Four isostructural 1D LnCPs with rhomboid [Ln 4 (μ 3 -OH) 2 ]-based chainlike structure were obtained hydrothermally. • The Gd(III)-containing polymer displays a large MCE with − Δ S m max value of 37.11 J kg−1 K−1. • The Eu- and Tb-based polymers exhibit characteristic Eu(III)/Tb(III) luminescence. Four isostructural lanthanide coordination polymers with orotic acid (H 3 OA) as building ligand, {[Ln(HOA)(μ 3 -OH)(H 2 O) 2 ]·H 2 O} n (Ln = Eu (1); Gd (2); Tb (3); Dy (4)), were synthesized under hydrothermal conditions. Single-crystal X-ray diffraction analyses demonstrate that complexes 1 – 4 have an one-dimensional (1D) chainlike structure consisting of rhomboid [Ln 4 (μ 3 -OH) 2 ] unit and HOA2- linker. Magnetic studies indicate that 2 displays a large magnetocaloric effect with magnetic entropy value of 37.11 J kg−1 K−1 at 2.0 K for Δ H = 7.0 T. This is a considerable value among the reported molecular magnetic coolants, and has a great application potential in the field of ultra-low temperature refrigeration. In addition, the solid-state photophysical properties of 1 and 3 exhibit obvious characteristic Eu(III) and Tb(III) photoluminescence emission in the visible region, suggesting that Eu- and Tb-based luminescence were sensitized effectively by the energy transfer from the ligand to the metal centers. [ABSTRACT FROM AUTHOR]

• Six Cd(II)-based coordination polymers were obtained solvothermally. • The structures and magnetic / optical properties can be regulated by introducing different metal ions into the Cd(II) system. • The Cd(II)-Mn(II) system displays a significant MCE. • The Cd(II) and Cd-Na(I) systems show blue luminescence. One monometallic and five heterometallic coordination polymers (HCPs) based on homophthalic acid (H 2 HPA), [Cd 2 (HPA) 2 (H 2 O) 2 ]·H 2 O (1), [CdMn(HPA) 2 (H 2 O) 2 ]·H 2 O (2), [Cd 3 Co(HPA) 4 (H 2 O) 4 ]·2H 2 O (3), [CdCo(HPA) 2 (DMSO)(H 2 O) 2 ] (4), [CdNa 2 (HPA) 2 (μ 2 -H 2 O)(H 2 O)] (5) and [Cd 2 Na 2 (HPA) 3 (μ 2 -H 2 O)(H 2 O) 2 ] (6), were synthesized solvothermally. Complexes 1 - 3 have similar two-dimensional (2D) layer structures except that all or part six-coordinated Cd(II) ions in 1 were replaced by the six-coordinated Mn(II) or Co (II) ion in 2 and 3 , respectively. Complex 4 shows an 1D ladderlike structure, and 5 and 6 exhibit different 2D layer structures. The different structures of 3 / 4 and 5 / 6 could be assembled directly by controlling the different pH values with other same reaction conditions, respectively. Magnetic studies reveal that the introducing of para-magnetic Mn(II) and Co(II) ions endow antiferromagnetic interarions between the neigboring spins in 2 – 4 , and 2 with isotropic Mn(II) ion displays a significant cryogenic magnetocaloric effect with a maximum −Δ S m value of 19.29 J K−1 kg−1 at 2 K and Δ H = 7 T. In addition, the solid-state photophysical properties of 1, 5 and 6 display blue emissions centered at ca. 453 nm, 448 nm and 428 nm, respectively. One monometallic and five heterometallic CPs were synthesized controllably based on HPA2− ligand, and strong blue emissions and a large MCE of −ΔSm = 19.29 J K−1 kg−1 were observed. [Display omitted] [ABSTRACT FROM AUTHOR]

One three-dimensional Gd(III) coordination polymer with 1,2-phenylenediacetate (PDA 2 − ), [Gd 2 (PDA) 3 (H 2 O) 2 ]·3H 2 O (1), has been successfully synthesized and characterized. Single crystal X-ray diffraction analysis shows that 1 consists of 1D wave Gd-based chain unit and PDA 2 − linker. Magnetic studies suggest the presence of ferromagnetic Gd ⋯ Gd coupling in the 1D chain unit of 1. Meanwhile, 1 has a significant cryogenic magnetocaloric effect with the maximum − ΔS m of 33.44 at 2 K and 7 T. [ABSTRACT FROM AUTHOR]

One 2D Gd(III)-based polymer with trans -aconitate ligand was synthesized solvothermally and displays a large cryogenic MCE with the maximum −ΔS m value of 35.89 J kg−1 K−1 at 2 K and Δ H =7 T. • The first Gd(III) polymer based on trans -aconitate ligand was prepared solvothermally. • The polymer owns a 2D layer structure with a metal skeleton of co-edge parallelogram. • The polymer displays a significant MCE of −Δ S m = 35.89 J kg−1 K−1. One two-dimensional Gd(III) coordination polymer based on trans -aconitic acid (H 3 ANA) ligand, [Gd(ANA)(DMF)(H 2 O) 2 ] n (1), was prepared solvothermally and characterized structurally. Single crystal X-ray diffraction analysis reveals that complex 1 crystallizes in monoclinic P 2 1 /c space group and possesses a 2D layer structure containing 3-connected Gd(III) ion and tridentate ANA3− ligand. The 2D structure owns a metal skeleton of co-edge parallelogram with the Gd⋯Gd distances of 8.36 (1) Å × 9.48 (1) Å. Magnetic studies demonstrate that 1 displays weak ferromagnetic interaction between the neighboring Gd(III) ions from the adjacent 2D layers, and has a large cryogenic magnetocaloric effect with the maximum − ΔS m value of 35.89 J kg−1 K−1 at 2 K and Δ H = 7 T. [ABSTRACT FROM AUTHOR]

One 1D Cd(II)-Mn(II) heterometallic coordination polymer was synthesized based on 2-methylenesuccinate ligand, and displays a large MCE with the maximum −ΔS m value of 21.93 J K−1 kg−1 at 2 K and Δ H =7 T. • One 1D Cd(II)-Mn(II) heterometallic polymer was obtained. • The polymer shows a large MCE. • The polymer is the first Cd(II)-Mn(II) based molecule magnetic refrigerant. One one-dimensional Cd(II)-Mn(II) heterometallic coordination polymer with 2-methylenesuccinate (MSA2−), [CdMn(MSA) 2 (H 2 O) 5 ]·3H 2 O (1), has been successfully prepared and characterized. Single crystal X-ray diffraction analysis reveals that 1 crystallizes in monoclinic P 2 1 / c space group and has a 1D chain structure. The introduction of diamagnetic Cd(II) ion helps separate the neighboring Mn(II) ions well to prevent the strong Mn(II)-Mn(II) antiferromagnetic interaction. Magnetic studies show that 1 has a great cryogenic magnetocaloric effect with the maximum − Δ S m value of 21.93 J K−1 kg−1 at 2 K and Δ H = 7 T. This is the first example for Cd(II)-Mn(II) based molecule magnetic refrigerant. [ABSTRACT FROM AUTHOR]

Two series of lanthanide complexes based on 4-chlorophenylacetic acid (HCPA), dinuclear [Ln 2 (CPA) 6 (DMF) 2 (H 2 O) 2 ] (Ln = Eu (1); Gd (2); Tb (3); Dy (4)) and one-dimensional (1D) linear [Ln 2 (CPA) 6 (H 2 O)] n (Ln = Eu (5); Gd (6); Tb (7); Dy (8)), were prepared, which are sensitive to the pH value. The dinuclear structure can be obtained when the pH value was controlled to be about 4.2, while the 1D structure can be formed when the pH value is ca. 5.1. The structure transformation of the dinuclear to 1D analogue at different pH values indicates that the CPA− ligand has a better affinity to replace the H 2 O/DMF molecule to bridge the neighboring Ln3+ ions to form the 1D structure at a higher pH value (∼5.1). The magnetic studies show that complexes 2 and 6 with isotropic Gd3+ ion display significant cryogenic magnetocaloric effect with a maximum −ΔS m value of 20.27 J kg−1 K−1 at 3 K and 7 T and 22.50 J kg−1 K−1 at 2 K and 7 T, respectively. Furthermore, the solid-state photophysical properties of 1 / 5 and 3 / 7 were studied and respectively exhibit strong characteristic emission peaks of Eu3+ and Tb3+ ions in the visible region, indicating that Eu- and Tb-based luminescences are sensitized effectively by the energy transfe from the ligand to the spin centers. Two series of dinuclear and 1D lanthanide complexes have been successfully prepared with HCPA, and are sensitive to pH value. The Gd-containing complexes display significant MCE, and the Eu- and Tb-based polymers exhibit strong characteristic lanthanide luminescence. Image 1 • Two series of lanthanide complexes were obtained solvothermally. • The dinuclear or 1D complexes are sensitive to the pH value. • The Gd-based complexes display significant MCE. • The Eu- and Tb-based complexes display characteristic Eu3+/Tb3+ luminescence. [ABSTRACT FROM AUTHOR]