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A rare 3D porous inorganic–organic polyoxoniobate framework based on the cubic polyoxoniobate-cupric-complex cage {[Cu(en)2]@{[Cu2(en)2(trz)2]6(Nb68O188)}} (1a), has been successfully synthesized b...

A rare 3D porous chiral polyoxoniobate framework, [Cu(en)2(H2O)]2{[Cu(en)]4[Cu(en)2]5 {[Cu(en)2KNb24O72H10]2}·6en·70H2O(1) (en = ethylenediamine) based on two types of isomeric {Cu(en)2KNb24O72H10} clusters (α-CuKNb24 and β-CuKNb24) has been synthesized by a hydrothermal reaction. Interestingly, the α-CuKNb24 and β-CuKNb24 clusters are connected by cupric complexes to form chiral helical pillars with left-handedness (L-α-CuKNb24) and right-handedness (R-β-CuKNb24). To our knowledge, compound 1 is the first polyoxometalate-based MOF with a 4-connected neb-type topology structure within polyoxometalate chemistry. This compound also exhibits proton conduction and strong water vapor adsorption properties.

Two unique heterometallic cluster organic frameworks, [Cd4 MnIII 4 MnII 6 (Tri)4 (CH3 COO)14 (μ4 -O)2 (μ3 -O)2 (H2 O)2 ] Cd(H2 O)2 ⋅9 H2 O (1) and Cu[Cd5 Cu6 (Tri)4 (CH3 COO)9 (H2 O)4 ]2 (CH3 COO)3 ⋅24 H2 O (2) (H3 Tri=2-(hydroxymethyl)-2-(pyridine-4-yl)-1,3-propanediol), have been successfully prepared by employing a bifunctional tripodal alcohol ligand as a structure-directing agent. Crystal structure analyses reveal that 1 represents a rare example of frameworks constructed from Cd-Mn heterometallic chains, and 2 is the first heterometallic MOF based on highest-nuclear Cd-Cu heterometallic cluster building blocks. Furthermore, the magnetic properties and gas adsorption abilities of 1 and 2 were systematically studied.

The first two inorganic-organic hybrid three-dimensional (3D) polyoxotantalates (POTas) and the first two inorganic-organic hybrid 2D POTas have been obtained. All of these high-dimensional POTas are built from a new-type POTa dimeric cluster {Cu(en)(Ta6O19)}2/{Cu(enMe)(Ta6O19)}2 (en = ethylenediamine, enMe = 1,2-diaminopropane) bridged by copper complexes. Interestingly, extended POTas 1 and 3 can undergo single-crystal to single-crystal structural transformations triggered by water.

A nested Cu24@Cu72 copper-organic framework, [Cu5(bdc)4(ina)2(H2O)3]·solvent (1, H2bdc = 1,3-benzenedicarboxylic acid and Hina = isonicotinic acid) based on paddlewheel Cu2(COO)4 SBUs, has been synthesized. There are three types of cages with different sizes and shapes: Cu24-cage, Cu60-cage and Cu72-cage. The Cu72-cage, which is the highest-nuclearity Cu-cage reported to date, encapsulates a Cu24-cage to form a double-walled Cu24@Cu72 cage-within-cage structure. Dye adsorption studies reveal that compound 1 can rapidly and selectively adsorb cationic dyes.

An unusual high-valent Sb(V)-based unit [SbL2]− (L = 2-(hydroxymethyl)-2-(pyridin-4-yl)-1,3-propanediol) was developed for the first time to combine with various cuprous-halide clusters for the construction of a brand-new class of heterometallic MOFs. This work not only promotes the limited development of Sb-based MOFs, but also provides a practical strategy for developing new types of composite materials.

This work demonstrates a new Lindqvist-like [FeIII6(μ6-O)L4Cl6]2- (Fe6, L = 2-(hydroxymethyl)-2-(pyridin-4-yl)-1,3-propanediol) cluster for the construction of a novel class of Fe-cluster organic frameworks. The novel Fe6 cluster can be used to build not only a homometallic MOF, but also a heterometallic MOF by introducing copper halide clusters to the reaction system. In particular, the heterometallic MOF achieved a skillful combination of Fe6 SBU and cuprous-halide clusters for the first time. Our synthesis strategy opens up an effective avenue to novel Fe-cluster-based MOF materials.

Two zeolite-like cluster organic frameworks based on Cd-Cu/Mn-Cu heterometallic supertetrahedral secondary building units have been successfully constructed under solvothermal conditions, namely, Cu[Cd4Cu6(L)4(H2O)18](Ac)9⋅DMA⋅3 H2O (1), and Cu[Mn4Cu6(L)4(Ac)3(H2O)12](Ac)6⋅CH3CN⋅13 H2O (2), where H3L=2-(hydroxymethyl)-2-(pyridin-4-yl)-1,3-propanediol, Ac=CH3COO−, DMA=N,N′-dimethylacetamide. Single-crystal X-ray structural analysis reveals that both 1 and 2 exhibit 3-dimensional zeolite-like architectures with similar 4-connected components, but possess definitely different topologies of diamondoid (dia) and uncommon lonsdaleite (lon), respectively. 1 and 2 represent the first cases of zeolite-like cluster organic frameworks containing Cd-Cu/Mn-Cu heterometallic supertetrahedral secondary building units. Furthermore, the magnetic properties and porous nature of 1 and 2 were also studied.

A rare and novel Cr-substituted polyoxoniobate (PONb), [Cr2.5Nb27.5O66(OH)20(H2O)2]7-, has been synthesized by a combination of hydrothermal and conventional solution methods. The PONb shows an unknown tetrameric structure, which is the largest Cr-containing PONb to date. Interestingly, every two PONb tetramers can be joined together by alkali-metal cations to form a discrete cubelike ionic cluster. The obtained PONb not only enriches the very limited members of the Cr-substituted PONb family but also exhibits high ionic conductivity.

During the past decade, research on the design and synthesis of zeolite-like metal-organic frameworks (ZMOFs) has developed greatly. As an important subclass of ZMOFs, zeolite-like cluster organic frameworks (ZCOFs) built from 4-connected metal-cluster secondary building units (SBUs) and appropriate linear organic ligand bridges have attracted sustained interest, because such materials not only integrate the merits of inorganic zeolites, ZMOFs, and metal clusters, including interesting topologies, high surface areas, extra-large cavities and channels, structural tunability, and unique physicochemical properties from various metal clusters, but also open up a new avenue to design and fabricate hybrid zeolite-like materials that have many potential applications in material sciences. In this review, recent developments in ZCOFs are summarized by classifying the ZCOFs into four categories according to the composition of the SBUs: 1) ZCOFs based on metal-halide cluster SBUs, 2) ZCOFs based on metal-oxygen cluster SBUs, 3) ZCOFs based on metal-chalcogen cluster SBUs, and 4) ZCOFs based on mixed types of metal-cluster SBUs. Besides, challenges associated with the design and synthesis of ZCOFs and the vast potential of this area are also discussed.

The two novel cluster organic frameworks based on heterometallic supertetrahedral cluster secondary building units (SBUs) [Cd4Cu6(L)4(Ac)7(H2O)4](Ac)·7H2O (1) and [Mn4Cu6(L)4(Ac)4.5(H2O)9]CuCN(Ac)3.5·H2O (2), where H3L = 2-(hydroxymethyl)-2-(pyridin-4-yl)-1,3-propanediol and Ac = CH3COO–, have been prepared under solvothermal conditions. 1 and 2 are the first cases of cluster organic frameworks containing Cd-Cu/Mn-Cu heterometallic supertetrahedral cluster SBUs. Furthermore, 1 and 2 show an integration of magnetic properties and adsorption properties from both the heterometallic cluster secondary building units and the framework in a porous material.