Structure and Magnetocaloric Effect of Two Kinds of Ln-MnIIHeterometallic Coordination Polymers Produced by Fractional Crystallization

Postsynthetic Installation of Lanthanide Cubane Clusters in a 3D Hydrogen-Bonded Framework of IrIII4ZnII4 Multicarboxylates

Immersing single crystals of (Δ)4-K6[Ir4Zn4O(l-cysteinate)12]·nH2O (K6[1Ir]·nH2O) bearing 12 free carboxylate groups, which was newly prepared from Δ-H3[Ir(l-cysteinate)3], ZnBr2, ZnO, and KOH, in an aqueous solution of lanthanide(III) acetate produced Ln2[1Ir]·nH2O (2Ln; Ln = LaIII, CeIII, PrIII, and NdIII) and Ln0.33[Ln4(OH)4(OAc)3(H2O)7][1Ir]·nH2O (3Ln; Ln = SmIII, EuIII, GdIII, TbIII, DyIII, ErIII, HoIII, TmIII, YbIII, and LuIII) in a single-crystal-to-single-crystal transformation manner. X-ray crystallography showed that the KI ions in K6[1Ir]·nH2O are completely exchanged by the LnIII ions in 2Ln and 3Ln, retaining the 3D hydrogen-bonded framework that consists of the IrIII4ZnII4 complex anions of [1Ir]6-. While 2Ln contained the LnIII ions as isolated aqua species, the LnIII ions in 3Ln existed as cationic cubane clusters of [Ln4(OH)4(OAc)3(H2O)7]5+; these were linked by [1Ir]6- anions through carboxylate groups in a 3D polymeric structure. 3Ln showed magnetic and photoluminescence properties that are characteristically observed for discrete LnIII species in the solid state.

Gd(III)-based metal-organic frameworks and coordination polymers for magnetic refrigeration

As the alternatives of expensive and increasingly shortage 3He for ultralow-temperaturerefrigeration, molecule-based magnetorefrigerant materials have attracted much attention in the past decades. Among them, Gd(III)-based metal-organic frameworks and coordination polymers...

Single-Crystal-to-Single-Crystal Installation of Ln4 (OH)4 Cubanes in an Anionic Metallosupramolecular Framework

Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single-crystal-to-single-crystal (SCSC) transformation is presented. Soaking single crystals of K₆ [Rh₄ Zn₄ O(l-cys)₁₂ ] (K₆ [1]; l-H₂ cys=l-cysteine) in a water/ethanol solution containing Ln(OAc)₃ (Ln³⁺ =lanthanide ion) results in the exchange of K⁺ by Ln³⁺ with retention of the single crystallinity, producing Ln₂ [1] (2_Ln ) and Ln_0.33 [Ln₄ (OH)₄ (OAc)₃ (H₂ O)₇ ][1] (3_Ln ) for early and late lanthanides, respectively. While the Ln³⁺ ions in 2_Ln exist as disordered aqua species, those in 3_Ln form ordered hydroxide-bridged cubane clusters that connect [1]^6- anions in a 3D metal-organic framework through coordination bonds with carboxylate groups. This study shows the utility of an anionic metallosupramolecular framework with carboxylate groups for the creation of a series of metal cubanes that have great potential for various applications, such as magnetic materials and heterogeneous catalysts.

Sequential Transformation of Zirconium(IV)-MOFs into Heterobimetallic MOFs Bearing Magnetic Anisotropic Cobalt(II) Centers

Heterometallic metal-organic frameworks (MOFs) allow the precise placement of various metals at atomic precision within a porous framework. This new level of control by MOFs promises fascinating advances in basic science and application. However, the rational design and synthesis of heterometallic MOFs remains a challenge due to the complexity of the heterometallic systems. Herein, we show that bimetallic MOFs with MX₂ (INA)₄ moieties (INA=isonicotinate; M=Co²⁺ or Fe²⁺ ; X=OH^- , Cl^- , Br^- , I^- , NCS^- , or NCSe^- ) can be generated by the sequential modification of a Zr-based MOF. This multi-step modification not only replaced the linear organic linker with a square planar MX₂ (INA)₄ unit, but also altered the symmetry, unit cell, and topology of the parent structure. Single-crystal to single-crystal transformation is realized so that snapshots for transition process were captured by successive single-crystal X-ray diffraction. Furthermore, the installation of Co(NCS)₂ (INA)₄ endows field-induced slow magnetic relaxation property to the diamagnetic Zr-MOF.

A novel alb metalloring organic framework with a {Ni12Gd24} cage exhibiting a significant magnetocaloric effect

With the aid of a bifunctional 6-mercaptonicotinic acid ligand, a novel {Ni₁₂Gd₂₄} cage-based (6, 12)-c alb-MROF that is assembled from a {Gd₄(OH)₄(COO)₆} trigonal-prism building unit and a {Ni₆S₁₂} hexagonal-prism molecular building block has been synthesized for the first time. It exhibits a large MCE value of 29.86 J kg^-1 K^-1 for ΔH = 8 T at 2 K.