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Abstract: Three new nickel(II) complexes [Ni2(btec)(azopy)2(H2O)8]·2H2O (1), {[Ni(H2btec)(azopy)(H2O)2]·(azopy)} n (2) and {[Ni4(btec)2(azopy)3(H2O)10]·8H2O} n (3) (H4btec=1,2,4,5-benzenetetracarboxylic acid; azopy=4,4′-azobispyridine) have been synthesized by tuning the reaction temperature and the metal–ligand ratio. They were characterized by single-crystal X-ray diffraction and elemental analysis. 1 shows a binuclear structure, 2 exhibits a 2D grid, and 3 features an interesting 3D framework with (63)(4.62)(42.62.82) topology formed by two types of interlocked 2D layers. [Copyright &y& Elsevier]

A cobalt(II) complex and manganese(II) coordination polymer, formulated as [Co2(H2btca)(mbpy)4][H2btca]·4H2O (1) and {Mn2(btca)(mbpy)2(H2O)2}n (2) (H4btca = 1,2,4,5-benzenetetracarboxylic acid; mbpy = 4,4′-dimethyl-2,2′-bipyridyl), constructed by mixed bipyridine-tetracarboxylic ligands were synthesized and characterized. Single-crystal structural analyses reveal that compound 1 is a discrete neutral binuclear molecule, while compound 2 is a two-dimensional (2D) coordination polymer. The metal ions in these compounds are well isolated, with an intramolecular Co2+⋯Co2+ distance of 9.170 Å for 1 and Mn2+⋯Mn2+ separation of 10.984 and 11.164 Å for 2 due to the bulk tetracarboxylic linker. This isolation gives rise to a single-ion magnetism origin of the compounds. Magnetic studies reveal a large zero-field splitting parameter D of 82.6 cm−1 for 1, while a very small D of 0.42 cm−1 was observed for 2. Interestingly, dynamic ac magnetic measurements exhibited slow magnetic relaxation under the external dc field of the two compounds, revealing the field-supported single-ion magnet (SIM) of 1 and 2. The detailed theoretical calculations were further applied to understand the electronic structures, magnetic anisotropy, and relaxation dynamics in 1 and 2. Combined with our recently reported compound (Eur. J. Inorg. Chem., 2022, e202200354), the foregoing results provide not only a rare binuclear cobalt(II) SIM and the first 2D manganese(II) SIM coordination polymer but also a bipyridine-tetracarboxylic ligand approach toward novel SIMs. [ABSTRACT FROM AUTHOR]

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]

Two novel heterometallic Cu(II)–Cd(II) coordination polymers, two-dimensional (2D) [Cu2Cd(MMA)2(NTA)2(H2O)2]n (1) and one-dimensional (1D) {[CuCd(MMA)2(H2O)6]·4H2O}n (2), were synthesized with methylmalonic acid (H2MMA) and nicotinic acid (HNTA) as mixed reactants under the conditions of 100 °C and room temperature, respectively. Complex 1 has a 2D layer structure consisting of the tetranuclear [Cu2Cd2] cluster-based 1D chain unit and NTA− linker. 2 exhibits a 1D chain structure with the Cu2+ and Cd2+ ions alternately bridged by the MMA2− ligand. Magnetic studies show that the magnetic interactions for the neighboring Cu2+ ions are both antiferromagnetic within and between the [Cu2Cd2] cluster of the 1D chain in 1 (Jd = −1.39(1) cm−1 and Jc = −1.77(1) cm−1) and there is predominantly ferromagnetic coupling in the 1D chain of 2 (J = 4.96(1) cm−1). Furthermore, 1 displayed antiferromagnetic ordering at lower temperature with TN = 4.0 K. [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 carboxylate-bridged 1D CPs (1) with linear trinuclear [Co 3 ] cluster unit was obtained and the magneto-structural correlations were discussed detailedly based on a linear trinuclear [Co 3 ] magnetic model with split and summation of the mixed carboxylate bridges. [Display omitted] • One new carboxylate-bridged 1D polymer containing linear trinuclear [Co 3 ] cluster unit was obtained. • The magneto-structural correlation was discussed quantificationally based on a new linear trinuclear [Co 3 ] magnetic mode. • This provides a new way for quantitative analysis of the magnetic coupling through mixed brigdes. One carboxylate-bridged coordination polymer, [Co 3 (MSA) 3 (H 2 O) 6 ] n (1), was synthesized under hydrothermal condition based on Co2+ ion and dicarboxylic acid ligand of 2-methylenesuccinic acid (H 2 MSA). Complex 1 has an one-dimensional (1D) linear chain structure consisting of linear trinuclear [Co 3 ] cluster node and mixed bridges of η 2-O carboxylate and syn - syn carboxylate. The magneto-structural correlation of 1 was studied based on a new linear trinuclear [Co 3 ] cluster magnetic model with split and summation of the mixed carboxylate bridges. The satisfying results suggest that the syn - syn carboxylate mediates antiferromagnetic interactions and the η 2-O carboxylate bridges with different Co O carboxylate Co angles could mediate ferromagnetic (<98°) or antiferromagnetic coupling (>98°), respectively. [ABSTRACT FROM AUTHOR]

With flexible 2-methylenesuccinate acid (H 2 MSA) and rigid 4, 4′-bipyridine (bpy) as mixed ligands, two three-dimensional (3D) metal−organic frameworks (MOFs), {[Zn 3 (μ 2 -OH) 2 (MSA) 2 (bpy) 2 ]·4H 2 O} n (1) and {[Cd(MSA)(bpy)]·2H 2 O} n (2), were obtained solvothermally. Complexes 1 and 2 both have a 3D framework structures, which include respectively a linear trinuclear [Zn 3 ] or a rare dinuclear [Cd 2 ] cluster node that consisting of two seven-coordinated Cd(II) ions. The adjacent [Zn 3 ] or [Cd 2 ] nodes in 1 and 2 are firstly linked together by the MSA2− ligand to form a 1D chain or a 2D layer unit respectively, which are further bridged by the bpy linkers to produce the 3D framework structures. If treating the [Zn 3 ] and [Cd 2 ] cluster as 4- and 6-connected nodes, the 3D frameworks of 1 and 2 can be simplified into a CdSO 4 topological network with a Schläfli symbol of (65.8) and a rob network with a Schläfli symbol of (48.66.8), respectively. The PXRD patterns suggest that 1 and 2 have good stability when soaked in water for at least 48 h. The fluorescence sensing properties of 1 and 2 toward different metal inorganic ions were investigated, and two complexes both could sense Fe3+, MnO 4 − and Cr 2 O 7 2− in aqueous solution with high sensitivity and selectivity (the LODs were 3.20 μM, 1.54 μM and 1.95 μM for 1 , 1.15 μM, 0.48 μM and 1.23 μM for 2 , respectively) as well as good recircularity. In addition, the mechanism of the selective luminescence quenching response for Fe3+, MnO 4 − and Cr 2 O 7 2− could be attributed to the energy competition between the excitation of complex 1 / 2 and the ultraviolet absorption of responsive substances. [Display omitted] • Two 3D luminescent MOFs were obtained by a strategy of rigid-flexible co-linkers. • The frameworks contain rare linear trinuclear [Zn 3 ] or dinuclear [Cd 2 ] cluster units respectively. • The complexes displayed good luminescent properties in water. • The complexes could behave as multi-target probes to sense Fe3+, MnO 4 − and Cr 2 O 7 2− with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Three coordination polymers, [Ag4(bpy)3(pztc)] n (1), {[Ag6(bpy)2(pztc)(CN)2] · 2.6H2O} n (2), and {[Ag2(H2pdtc)(bpy)2] · 3H2O} n (3) (H4pztc = pyrazine-2,3,5,6-tetracarboxylic acid, H4pdtc = pyridine-2,3,5,6-tetracarboxylic acid, bpy = 4,4′-bipyridine), have been synthesized and characterized by elemental analysis, IR spectra, thermogravimetric analysis, UV spectra, fluorescent spectra, and single-crystal X-ray diffraction. Complex 1 displays a 3-D network with infinite channels of about 6.4 × 3.1 Å2 along the a-axis. The structure of 1 can be simplified as a 3,4,4-connected framework. Complex 2 displays a 3-D network and can be simplified as a 6,6-connected pcu framework. Complex 3 shows a 1-D chain structure and the chains form a 2-D layer structure by hydrogen bonds. Complexes 1–3 emit intense fluorescence at around 500 nm on excitation at 340 nm, 320 nm, and 340 nm, respectively. [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]