Guest DMF Molecules Research Articles

Zn(II) and Co(II) 3D Coordination Polymers Based on 2-Iodoterephtalic Acid and 1,2-bis(4-pyridyl)ethane: Structures and Sorption Properties.

Metal-organic frameworks [M2(2-I-bdc)2bpe] (M = Zn(II) (1), Co(II) (2), 2-I-bdc = 2-iodoterephtalic acid, and bpe = 1,2-bis(4-pyridyl)ethane) were prepared and characterized by X-ray diffractometry. Both compounds retain their 3D structure after the removal of guest DMF molecules. Selectivity of sorption of different organic substrates from the gas phase was investigated for both complexes.

Design and Construction of a Chiral Cd(II)-MOF from Achiral Precursors: Synthesis, Crystal Structure and Catalytic Activity toward C-C and C-N Bond Forming Reactions.

Using achiral components, a V-shaped dicarboxylic acid (H2L) and a conformationally flexible bidentate linker (bpp), a thermally stable chiral metal organic framework {[Cd(bpp)(L)(H2O)]·DMF} n (1), where H2L = 4,4'-(dimethylsilanediyl)bis-benzoic acid, bpp = 1,3-bis(4-pyridyl)propane and DMF = N,N-dimethylformamide, has been solvothermally synthesized and crystallographically characterized. It consists of 1D helical chains linked at the cadmium centers resulting in an overall 2D framework. Its microporous nature was confirmed by gas-sorption measurements. Upon thermal activation of 1, where both guest DMF molecules present in the 1D open channels and the coordinated H2O molecules are removed, its active metal site shows Lewis acid character to be an excellent heterogeneous catalyst for the C-C (Knoevenagel condensation reaction) and C-N (Strecker) bond forming reactions.

Modification of Network and Pore Dimensionality in Metal–Organic Frameworks Containing a Secondary Phosphine Functionality

Three new metal–organic frameworks containing a triphenylphosphine moiety, namely, [Zn3(tpp)2(DMF)2]·nDMF (1), [Zn3(tpp)2(4,4′-bpy)2]·nDMF (2), and [Zn3(tpp)2(3,3′-bpy)]·nDMF (3), were synthesized using 4,4′,4″-phosphanetriyltribenzoic acid (H3tpp) as a tritopic linker. The absence or presence of additional N-donor linker molecules in the reaction mixture lead to the formation of (3,6)-c layered, (3,8)-c pillared layered, or (3,4,6)-c frameworks. Compound 1 is composed of a trinuclear zinc secondary building unit (SBU) and the tpp3– anion arranged in a layered (3,6)-c network with kgd topology. There are DMF guest molecules coordinated to the terminal Zn atoms of the trinuclear inorganic SBU. The addition of the neutral N-donor molecules 3,3′-bipyridine (3,3′-bpy) and 4,4′-bipyridine (4,4′-bpy) as second organic linker molecule lead to an increase of dimensionality of the networks. Compound 2 is a (3,4,6)-nodal three-dimensional MOF. Its structure consists of two equivalent interpenetrated nets with the point symbol (52·64)(52·6)2(54·66·72·8·92) containing solvent filled pockets. The free electron pair of the phosphorus atom of the triphenylphosphine moiety is pointing toward the zero-dimensional pores. The structure of 3 can be described as layers of 1 which are connected by 3,3′-bipyridine as pillar into a three-dimensional (3,8)-c network with the point symbol (43)2(46·618·84). The non-interpenetrated structure of 3 contains a solvent filled three-dimensional pore system. All three materials exhibit uptake of CO2 at 195 K after removal of the guest DMF molecules. This is particularly surprising for 2, with its zero-dimensional pores in the single-crystal structure and absence of N2 adsorption at 77 K. Compound 3 shows a large gate opening effect for CO2 adsorption at 195 K.

Field-Induced Slow Magnetic Relaxation and Gas Adsorption Properties of a Bifunctional Cobalt(II) Compound.

A new compound, {[Co(bmzbc)2] · 2DMF}n (JXNU-1, JXNU denotes Jiangxi Normal University), based on the 4-(benzimidazole-1-yl)benzoate (bmzbc(-)) ligand has been synthesized and structurally characterized. The Co(II) ions are bridged by the rod-like bmzbc(-) ligands to give a two-dimensional (2D) sheet wherein the Co(II) ions are spatially separated from each other by the long bmzbc(-) rods. The 2D sheets are further stacked into a 3D framework with 1D channels occluding the guest DMF molecules. Detailed magnetic studies show that the individual octahedral Co(II) ions in JXNU-1 exhibit field-induced slow magnetic relaxation, which is characteristic behavior of single-ion magnets (SIMs). The rarely observed positive value of zero-field splitting (ZFS) parameter D for the Co(II) ion in JXNU-1 demonstrates that JXNU-1 is a unique example of Co(II)-based SIMs with easy-plane anisotropy, which is also confirmed by the calculations. The microporous nature of JXNU-1 was established by measuring CO2 sorption isotherms. The abrupt changes observed in the C3H8 and C2H6 adsorption isotherms indicate that a structural transformation occurred in the gas-loading process. The long connection between the magnetic metal centers in JXNU-1 meets the requirements for construction of porosity and SIM in a well-defined network, harmoniously providing a good candidate of functional molecular materials exhibiting SIM and porosity.

Supramolecular assembly of a series of new coordination polymers based on 4,4′-(carbonylimino)dibenzoic acid: Syntheses, structures and photoluminescence investigation

Assembly reactions of acylamide-containing dicarboxylate ligand 4,4′-(carbonylimino)dibenzoic acid (H2L) with corresponding divalent metal ions resulted in the formation of seven new coordination polymers, namely Cd(L)(H2O) (1), Zn(L)(H2O) (2), Zn5(L)2(OH)6 (3), [Ni(L)(H2O)2]·H2O (4), [Cd(L)(py)(H2O)]·(DMF)·(C6H5Cl) (5), [Cd(L)(py)2]·2CH3OH (6) and [Mn (HL)2(py)2]·2DMF (7). In complex 1, the double chains composed CdII and L2− are connected by interlayer Cd–O bonds to form a three-dimensional architecture. Complex 2 exhibits a three-dimensional supramolecular architecture extended by hydrogen bonds involving O–H⋯O and N–H⋯O types. Complex 3 displays a three-dimensional framework consisting of zinc-hydroxide layers and L2− pillars. Complex 4 is also a supramolecular three-dimensional network generated from linkage of Ni–O chains via versatile hydrogen bonds. Complex 5 exhibits an interdigitated network in which the cavities are occupied by guest DMF and C6H5Cl molecules. In complex 6, two-dimensional square-grid network was generated by linkage of Cd2 units with L2− ligands. Mono-depronated ligand presents in complex 7. The adjacent [Mn(py)(HL)] chains are arranged parallel to each other by forming hydrogen bonding between the acylamide groups and guest DMF molecules. The stability properties of 2, 3, 4, 6 and 7 have been presented. In addition, photoluminescence properties of complexes 2, 3, 5 and 6 are investigated.

Vanadium Analogues of Nonfunctionalized and Amino‐Functionalized MOFs with MIL‐101 Topology – Synthesis, Characterization, and Gas Sorption Properties

AbstractSyntheses, characterization, and gas sorption properties of two new vanadium‐based metal–organic frameworks [V3OCl(DMF)2(BDC)3]·3.1DMF·10H2O·0.1BDC (V–MIL‐101 or 1) and [V3OCl(DMF)2(BDC–NH2)3]·2.8DMF·H2O·0.1BDC–NH2 (V–MIL‐101–NH2 or 2) (DMF = N,N′‐dimethylformamide; BDC = terephthalate; BDC–NH2 = 2‐aminoterephthalate) having MIL‐101 topology are presented. Compounds 1 and 2 were prepared under similar solvothermal conditions (150 °C, 24 h) in DMF by using VCl3 and H2BDC or H2BDC–NH2, respectively. Determination of lattice parameters from X‐ray powder diffraction (XRPD) patterns of thermally activated compounds revealed their structural similarity with chromium‐, iron‐, and aluminum‐based solids having two types of mesoporous cages and accessible metal sites. The phase purity of the compounds was ascertained by XRPD analysis, diffuse reflectance Fourier transform (DRIFT) spectroscopy, and elemental analysis. Thermogravimetric analyses (TGA) and temperature‐dependent XRPD (TDXRPD) experiments indicate that the compounds are stable up to 320 and 240 °C, respectively, under an argon atmosphere. Removal of the guest DMF molecules by thermal activation enables the compounds to adsorb significant amounts of N2 (690 and 555 cm3 g–1 at p/p0 = 1 for 1 and 2, respectively) and CO2 (9.0 and 4.3 mmol g–1 at 24.5 and 22.8 bar for 1 and 2, respectively).

A new microporous Cu(II)-isonicotinate framework with 8-connected bcu topology

Abstract A new microporous Cu(II)-isonicotinate framework Cu(int)2·DMF(1, int = isonicotinate; DMF = N,N-dimethylformamide) with large open channels filled by guest DMF molecules has been solvothermally synthesized and structurally characterized. It features a typical bcu topology by reducing the dinuclear Cu units as the 8-connected nodes. Such bcu-type framework is much stable after removal of the guest DMF molecules and shows notable CO2 sorption behavior.

Guest exchange dynamics in a flexible bilayer porous coordination polymer

A novel Cd(II)-organic framework [Cd(bpdc)(bpy)⋅DMF] (1) (H2bpdc = biphenyl-3,4′-dicarboxylic acid, bpy = 4,4′-bipyridine) has been synthesized by the solvothermal reaction of Cd2 + salt with H2bpdc and bpy in N,N-Dimethylformamide (DMF) solvent. Single crystal X-ray diffraction revealed that 1 has a two-dimensional (2D) bilayer structure, and the bilayers of 1 are further mutually interdigitated to form a 3D microporous framework. Guest exchange experiments for 1 with several organic solvents and water were performed, and the results display that ethanol can exchange with the guest DMF molecules in 1, but methanol, acetonitrile and water solvents can only induce 1 to extract its guest DMF molecules. Powder X-ray diffraction shows that 1 undergoes a small framework slip between the adjacent interdigitated bilayers triggered by the guest exchange, and the original framework can be restored after the exchanged samples soaked back in the DMF solvent, which demonstrated that 1 has dynamic and flexible interdigitated bilayer motif. The photoluminescent characterization shows that 1 displays blue-green emission in the solid state at room temperature.

A series of three-dimensional lanthanide(iii) coordination polymers of 2,5-dihydroxy-1,4-benzenedicarboxylic acid based on dinuclear lanthanide units

The reactions of Ln(NO3)3 with 2,5-dihydroxy-1,4-benzenedicarboxylic acid (H2-DHBDC) under solvothermal conditions produce a series of isomorphous lanthanide coordination polymers with the empirical formula {[Ln2(DHBDC)3(DMF)4](DMF)2}n (Ln = La(1), Nd(2), Sm(3), Gd(4), and Er(5)). Compound {[Ln2(DHBDC)3(DMF)4](DMF)2}n contains dinuclear Ln2(COO)6 units, which are linked by the –C6H2(OH)2– spacers to form a three-dimensional framework exhibiting α-Po topology (pcu-(412·63) net) based on dinuclear Ln2(COO)6 nodes. The three-dimensional framework shows one-dimensional open channels that accommodate the coordinated and guest DMF molecules. Gas adsorption measurements on compound 4 indicate that the desolvated solid of 4 adsorbs CO2 and shows nonporous behavior toward N2. The adsorption favoring CO2 over N2 may arise from the chemical environments of the host framework, which contains the polar –OH groups of the phenyl and the π-electrons of the ligands. Magnetic measurements on compound 4 indicate that there is an antiferromagnetic interaction between Gd3+ ions.

Multifunctional Homochiral Lanthanide Camphorates with Mixed Achiral Terephthalate Ligands

Seven homochiral lanthanide camphorates with mixed achiral terephthalate ligands, namely, {Ln(2)(cam)(2)(bdc)(H(2)O)(2)}·DMF [Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7); d-H(2)cam = d-(+)-camphoric acid; H(2)bdc = 1,4-benzenedicarboxylic acid; DMF = N,N'-dimethylformamide], have been solvothermally synthesized. Single-crystal X-ray diffraction analyses reveal that compounds 1-7 are isostructural and crystallize in orthorhombic, chiral space group P2(1)2(1)2(1). These structures feature three-dimensional open frameworks based on rodlike [Ln(2)(OCO)(6)(H(2)O)(2)](n) secondary building units, with the guest DMF molecules occupying the void space of the host {Ln(2)(cam)(3)(bdc)(H(2)O)(2)} framework. The photophysical and magnetic properties of some of these complexes have been investigated. Notably, the terbium compound 4 is highly emissive with a quantum yield of 63.68%. Additionally, thermogravimetric analyses, variable-temperature IR spectroscopy, and powder X-ray diffraction of 2 as a representative were performed to determine its thermal stability, which indicates that the framework still remains intact until 300 °C.

Anionic Metal–Organic Frameworks of Bismuth Benzenedicarboxylates: Synthesis, Structure and Ligand‐Sensitized Photoluminescence

AbstractFour organic–inorganic bismuth benzenedicarboxylate (bdc)frameworks, [Bi(1,4‐bdc)2(dmf)]·(dma)(dmf)2 (1), [Bi(1,4‐bdc)2]·(dma)(dmf) (2), [Bi4(1,4‐bdc)7(HIm)]·(dma)2(dmf)2 (3) and [Bi(1,4‐bdc)2]·(dma) (4) (where dma = dimethyl ammonium cation, HIm = imidazole and dmf = dimethylformamide) have been synthesized under solvothermal conditions, and their structures were determined by single‐crystal X‐ray diffraction. Compound 1 has a layer structure, whereas compounds 2–4 have three‐dimensional structures. All four frameworks are anionic and contain dma cations within cavities in their structures. Compounds 1–3 also contain coordinated and/or guest dmf molecules. The topologies of compounds 1–3 have 4‐connecting nodes; the layer structure in 1 is a corrugated (4,4)‐connected square lattice, but the three‐dimensional structures of 2 and 3 adopt the (dia) net topology. Compound 4 has a 6‐connecting node with a (pcu) net topology. The BiOn polyhedra are hemidirected with a stereochemically active lone pair of electrons in 2, but holodirected with astereochemically inactive lone pair of electrons in 1, 3 and 4. Tb3+‐ and Eu3+‐doped and co‐doped 3 and 4 emit intense, ligand‐sensitized green, red or orange luminescence, respectively.

Nanoporous lanthanide-carboxylate frameworks based on 5-nitroisophthalic acid

The reactions of lanthanide nitrates with 5-nitroisophthalic acid (ab. 5-H(2)nip) in DMF and ethanol (1 : 1) mixed solution gave rise to three nanoporous lanthanide polymers, {[Ln(2)(5-nip)(3)(DMF)(4)](DMF)(2)}(n) (Ln = Nd (), Dy (), Ho (), 5-nip = 5-nitroisophthalate). Single-crystal X-ray diffraction analyses reveal that they are isomorphous and feature three-dimensional metal-organic frameworks with two-dimensional intersecting channels occupied by guest DMF molecules constructed from the linkage of dimer Ln(2)C(6)O(12) SBUs and 5-nip ligands. The guest DMF molecules can be reversibly removed from as identified using TGA-DSC and PXRD. The heat of adsorption of the guest-free sample of with DMF was measured with a value of 10.3 kJ mol(-1) by an RD496-III type microcalorimeter. In addition, the photoluminescent property of was investigated.

A homochiral metal-organic framework with amino-functionalized pores

A new metal-organic framework [Zn2(Cam)2(apyr) ⊃ 2DMF], 4 (apyr = 2-aminopyrazine) has been synthesized by the high temperature equimolar reactions of zinc nitrate with the (+)-camphoric acid (H2Cam) in neat DMF solution. The crystal structure of 4 was determined by X-ray analyses and found to be a porous cubic network composed of linked zinc camphorate “paddlewheel” secondary building units and apyr pillars. The apyr pillars give amino-functionality to the pores. The extended structure of 4 contains guest DMF molecules trapped within the channels. Compound 4 is potentially porous and thermogravimetric analysis is consistent with the initial loss of guest DMF between 75 and 190°C, with the decomposition of the material at 430°C. The material was found to take up racemic alcohols into its pores, however no enantioselectivity was achieved. Reactivity studies of 4 with acetaldehyde show that the amino groups in the pores can be transformed into imine functionalities via post-synthetic covalent modification.