Infinite Rod-shaped Secondary Building Units Research Articles

Rational Design and Reticulation of Infinite qbe Rod Secondary Building Units into Metal-Organic Frameworks through a Global Desymmetrization Approach for Inverse C3 H8 /C3 H6 Separation.

The development of reticular chemistry has enabled the construction of a large array of metal-organic frameworks (MOFs) with diverse net topologies and functions. However, dominating this class of materials are those built from discrete/finite secondary building units (SBUs), yet the designed synthesis of frameworks involving infinite rod-shaped SBUs remain underdeveloped. Here, by virtue of a global linker desymmetrization approach, we successfully targeted a novel Cu-MOF (Cu-ASY) incorporating infinite Cu-carboxylate rod SBUs with its structure determined by micro electron diffraction (MicroED) crystallography. Interestingly, the rod SBU can be simplified as a unique cylindric sphere packing qbe tubule made of [43 .62 ] tiles, which further connect the tritopic linkers to give a newly discovered 3,5-connected gfc net. Cu-ASY is a permanent ultramicroporous material featuring 1D channels with highly inert surfaces and shows a preferential adsorption of propane (C3 H8 ) over propene (C3 H6 ). The efficiency of C3 H8 selective Cu-ASY is validated by multicycle breakthrough experiments, giving C3 H6 productivity of 2.2 L/kg. Density functional theory (DFT) calculations reveal that C3 H8 molecules form multiple C-H⋅⋅⋅π and atypical C-H⋅⋅⋅ H-C van der Waals interactions with the inner nonpolar surfaces. This work therefore highlights the linker desymmetrization as an encouraging and intriguing strategy for achieving unique MOF structures and properties.

A Homochiral Multifunctional Metal-Organic Framework with Rod-Shaped Secondary Building Units.

A new homochiral multifunctional metal-organic framework, [Zn2(CTBA)2·H2O] (JUC-112), was synthesized under solvothermal conditions, through the design of chiral ligand 4-(3-carboxy-2,2,3-trimethylcyclopentanecarboxamido) benzoic acid (H2CTBA) based on camphoric acid as building block. The crystal structure of the new material is a 2-dimensional (2D) chiral layer packed with infinite rod-shaped secondary building units (SBUs). The homochiral framework was identified by circular dichroism (CD) spectrum. Thermogravimetric measurement indicates its high thermal stability up to 450 °C. In addition, JUC-112 exhibits the capability of separating water from alcohols, second-order nonlinear optical effect, and photoluminescence.

Structural diversity of Zn(II)/Cd(II) coordination polymers constructed from mixed ligand systems of conformationally flexible azo functionalized bis-imidazolate and dicarboxylates

Six coordination polymers based on a conformationally flexible azo functionalized bis-imidazolate ligand bis(3-imidazol-1-ylphenyl)-diazene (L) with diverse conformations, namely, {[ZnL(tp)]·2H2O}n (1), [ZnL(ndc)]n (2), {[ZnL(ip)]·DMF}n (3), [Cd(L)0.5(tp)]n (4), {[CdL(ndc)]·0.625DMF}n (5) and [CdL(ip)]n (6), have been synthesized under solvothermal conditions with the aid of three different dicarboxylic acid ligands (H2tp=terephthalic acid, H2ndc=naphthalene-1,4-dicarboxylic acid, H2ip=isophthalic acid). Complexes 1–3 exhibit 2D+2D→3D polycatenation or 2D→2D interpenetration of (4, 4) sheets with metal ions as 4-connected nodes and ligands as linkers, while the layers are interpenetrated in different ways. Complex 4 possesses an unprecedented self-penetrating framework with a uninodal 8-connected with (416.55.67) topology based on infinite rod-shaped secondary building units (SBUs). Complex 5 displays a 3D 6-connected self-penetrated rob topology constructed from binuclear Cd(II) SBUs. Complex 6 features non-interpenetrated sql topology built on binuclear Cd(II) SBUs. The effects of the conformations of the L ligand, coordination modes of the dicarboxylic acids and metal ions on the diverse structures have been discussed. The thermal stability and luminescent properties of the CPs are also investigated.

Two isostructural fluorinated metal-organic frameworks with rare rod-packing architecture: syntheses, structures and luminescent properties

Abstract Two isostructural fluorinated metal-organic frameworks, formulated as [M 2(Fbix)(1,4-NDC)2] n (M=Cd for 1 and Mn for 2), were synthesized by employing 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) and the flexible fluorinated ligand 2,3,5,6-tetrafluoro-1,4-bis(imidazole-1-yl-methyl)benzene (Fbix) under hydrothermal conditions. Their structures were determined by single-crystal X-ray diffraction and further characterized by infrared spectroscopy, powder X-ray diffraction, and thermogravimetric analyses. Structure analyses have revealed that compounds 1 and 2 show an unusual hex net based on infinite rod-shaped secondary building units. The solid-state fluorescence spectra of 1 and 2 were measured and indicate a ligand-based emission for both complexes.

An unusual three-dimensional homochiral metal saccharate based on inorganic helical chains

Self-assembly of the D-saccharate (D-sacc) ligand and barium salt under hydrothermal conditions yields an unprecedented homochiral three-dimensional (3D) metal saccharate, namely, [Ba(D-sacc)]n (1), which is based on inorganic helical chains as infinite rod-shaped secondary building units (SBUs). The structure of compound 1 was determined by single-crystal X-ray diffraction analysis and further characterized by elemental analyses, IR spectrum, and thermogravimetric analysis. Compound 1 exhibits a novel 3D chiral architecture containing multidirectional helical chains, which is still rare in metal–organic complexes, especially in metal aldarates. To the best of our knowledge, compound 1 represents the first example of alkaline-earth metal aldarates featuring chiral and helical structures. Furthermore, the photoluminescent property of compound 1 was investigated in the solid state at room temperature.

Two three-dimensional pillared metal–olsalazine complexes based on infinite rod-shaped secondary building units

The first two three-dimensional (3D) pillared metal–olsalazine complexes, namely [Co(osa)0.5(bim)0.5(H2O)] (1) and [Cd(osa)0.5(bim)0.5(H2O)] (2) (H4osa=3,3-azo-bis(6-hydroxybenzoic acid), bim=1,4-bis(imidazol-1-yl)butane) have been hydrothermally synthesized and further characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, IR spectra and TG analyses. Compounds 1 and 2 are isostructural, and their frameworks are composed of infinite rod-shaped secondary building units (SBUs) that are bridged by osa ligands to form 2D layers, which are further pillared by bim ligands in the third dimension. To the best of our knowledge, it is the first time that 3D pillared-layer frameworks involving infinite rod-shaped SBUs have been obtained in the realm of metal–olsalazine complexes. The magnetic property of 1 and photoluminescence of 2 have also been investigated.

Design and construction of coordination polymers based on 2,2′-dinitro-4,4′-biphenyldicarboxylate and imidazole-based ligands: The effect of ligand length and metal ions

Five coordination polymers, Mn4(nbpdc)4(bip)(H2O)2 (1), Co5(nbpdc)4(bip)2(H2O)6(OH)2 (2), Cu5(nbpdc)4(bip)2(H2O)2(OH)2 (3), Zn5(nbpdc)4(bip)2(OH)2 (4), and Cd2(nbpdc)2(bip) (5), (H2nbpdc = 2,2′-dinitro-4,4′-biphenyldicarboxyl acid, bip = 1,5-bis(imidazole)pentane), have been prepared and structurally characterized. In these compounds, nbpdc and bip link different secondary building units (SBUs) to construct a variety of architectures based on different metals. Compound 1 presents a 3D hex net based on infinite rod-shaped SBUs. Compound 2 shows a 3D framework with mab topology based on Co5 clusters and exhibits an interesting self-penetration feature. Compound 3 presents a 3D framework with pcu topology constructed by Cu5 clusters. Compound 4 is a 3D framework with pcu topology based on infinite rod-shaped SBUs. Compound 5, like compound 4, also exhibits pcu topology constructed by rod-shaped SBUs, but they both possess different structures. The magnetic properties of compounds 1 and 2 have been characterized.

Design and construction of coordination polymers by 2,2′-dinitro-4,4′-biphenyldicarboxylate and imidazole-based ligands: diverse structures based on different metal ions

Six coordination polymers, [Mn2(nbpdc)2(bib)]n (1), [Co2(nbpdc)2(bib)1.5(H2O)2]n (2), [Ni2(nbpdc)2(bib)1.5(H2O)2]n (3), [Cu3(nbpdc)2(bib)(OH)2]n (4), [Zn2(nbpdc)2(bib)]n (5), and [Cd2(nbpdc)2(bib)(H2O)]n (6), (H2nbpdc = 2,2′-dinitro-4,4′-biphenyldicarboxylic acid, bib = 1,4-bis(imidazol-1-yl)butane), have been prepared and structurally characterized. In these compounds, nbpdc and bib link different secondary building units (SBUs) to construct various architectures based on different metals. Compounds 1 and 5 present a 3D pcu net based on an infinite rod-shaped SBU. Compounds 2 and 3 have the same 2D double-layer structure with a unique {412.52.6} topology, showing an interesting self-penetration feature. Compound 4 presents a 3D framework with hex topology. Compound 6 shows a 3D framework with unprecedented (412.513.63)(48.55.62) topology based on two different unusual infinite and finite SBUs, and has an interesting self-penetrating feature. Therefore, different metal ions influence the final structures of coordination polymers. Magnetic properties of compounds 1 and 4 have been characterized.

Lanthanide Coordination Polymers Constructed from Infinite Rod-Shaped Secondary Building Units and Flexible Ligands

Three lanthanide coordination polymers constructed from infinite rod-shaped secondary building units (SBUs), [Nd(2)(H(2)O)(2)(cis-chdc)(2)(trans-chdc)]2H(2)O (1), Nd(2)(H(2)O)(4)(trans-chdc)(3) (2), and [Sm(2)(H(2)O)(2)(cis-chdc)(trans-chdc)(2)]4H(2)O (3) (chdcH(2)=1,4-cyclohexanedicarboxylic acid), were hydrothermally synthesized and structurally characterized. The structures of 1-3 are modulated by different ratios of the cis and trans configurations of chdc(2-) ligands, which was achieved by temperature control in the hydrothermal reactions. Crystal-structure analysis revealed that 1 is a four-connected pcu-type rod packing network built from cross-linking of rod-shaped neodymium-oxygen SBUs by cis- and trans-chdc(2-) ligands in a 2:1 ratio, 2 displays a complicated six-connected hex-type rod packing structure built by connection of rod-shaped neodymium-oxygen SBUs and trans-chdc(2-) ligands, and 3 features an unprecedented five-connected rod packing pattern constructed from rod-shaped samarium-oxygen SBUs and cis- and trans-chdc(2-) ligands in a 1:2 ratio.

Photoluminescent metal-organic framework with hex topology constructed from infinite rod-shaped secondary building units and single e, e- trans-1,4-cyclohexanedicarboxylic dianion

Hydrothermal reaction produced a three-dimensional zinc 1,4-cyclohexanedicarboxylate formulated as Zn 5(μ 3-OH) 2( trans-chdc) 4 (chdc = 1,4-cyclohexanedicarboxylic dianion) in high purity and good yield, which is constructed from infinite rod-shaped Zn–O–C secondary building units interconnected by –C 6H 12-cyclohexane rings of the ligands. The topology of the framework can be regarded as hex type. Though it is synthesized from 1,4-cyclohexanedicarboxylic acid with mixed conformations ( trans and cis), interestingly, the ligands in the compound Zn 5(μ 3-OH) 2( trans-chdc) 4 are uniformly in e, e- trans conformation. This may be related to its synthetic conditions. Photoluminescence measurement reveals that the compound exhibits intense violet-blue fluorescent emission at room temperature. Origin of the emission can be assigned to intraligand transitions by comparison of the fluorescent emission bands for the free ligand chdcH 2 and the compound Zn 5(μ 3-OH) 2( trans-chdc) 4.