Carboxylate Secondary Building Units Research Articles

The Anisotropic Responses of a Flexible Metal-Organic Framework Constructed from Asymmetric Flexible Linkers and Heptanuclear Zinc Carboxylate Secondary Building Units.

A new porous and flexible metal–organic framework (MOF) has been synthesized from the flexible asymmetric linker N-(4-carboxyphenyl)succinamate (CSA) and heptanuclear zinc oxo-clusters of formula [Zn7O2(carboxylate)10DMF2] involving two coordinated terminal DMF ligands. The structural response of this MOF to the removal or exchange of its guest molecules has been probed using a combination of experimental and computational approaches. The topology of the material, involving double linker connections in the a and b directions and single linker connections along the c axis, is shown to be key in the material’s anisotropic response. The a and b directions remain locked during guest removal, whereas the c axis linker undergoes large changes significantly reducing the material’s void space. The changes to the c axis linker involve a combination of a hinge motion on the linker’s rigid side and conformational rearrangements on its flexible end, which were probed in detail during this process despite the presence of crystallographic disorder along this axis, which prevented accurate characterization by experimental methods alone. Although inactive during guest removal, the flexible ends of the a and b axis linkers are observed to play a prominent role during DMF to DMSO solvent exchange, facilitating the exchange reaction arising in the cluster.

Ionic liquid templated novel porous anionic cobalt(II) coordination framework based on rod-shaped metal-carboxylate chains

A novel porous anionic cobalt(II) coordination framework based on rod-shaped metal-carboxylate chains, [BMI][Co3(L)2(HCOO)(H2O)2] (1) (H3L = 3,4-bi(4-carboxyphenyl)-benzoic acid, [BMI]Br = 1-butyl-3-methylimidazolium bromide), has been prepared under the combination of solvothermal and ionothermal syntheses. [BMI]Br ionic liquid play a structure directing role and [BMI]+ cation is occluded into the ultimate structure. Complex 1 possesses 1D channels (11.4 × 13.6 Å) constructed by 1D cobalt(II)-carboxylate secondary building unit (SBU) and H3L ligands. The study suggests that [BMI]Br, the kind of molecular solvents as well as the anion of the cobalt(II) salts all play key roles in the formation of the title anionic framework.

Control of Interpenetration and Gas-Sorption Properties of Three Mn(II)-tris((4-carboxyl)phenylduryl)amine Frameworks by Tuning Solvent and Temperature

On the basis of the same reaction starting materials, microporous to mesoporous Mn(II)-tris((4-carboxyl)phenylduryl)amine frameworks (FIR-34 to FIR-36, FIR denotes Fujian Institute of Research) with different interpenetration structures have been obtained by applying different solvents and reaction temperatures. FIR-34 is an 8-fold interpenetrating dia framework constructed from small dinuclear [Mn2(COO)4] secondary building units (SBUs), while FIR-35 based on large Mn5 SBUs is a non-interpenetrating framework with (3,8)-connected tfz-d network. Both of them have low porosity. However, the other non-interpenetrating framework (FIR-36) with large mesopores is built by rod-shaped Mn(II)-carboxylate SBUs. Gas sorption measurements for FIR-36 give a Langmuir surface area of 825.3 m2·g–1 and a H2 uptake of 134.5 cm3·g–1 at 77 K and 1 bar.

Solvent‐Controlled Construction of Two 3D Manganese(II) Coordination Polymers Based on Flexible Tripodal Multicarboxylate Linker and Rod‐Shaped SBUs

AbstractTo further explore the coordination possibilities of the flexible tripodal ligand, 4,4′,4′′‐(benzene‐1,3,5‐triyl‐tris(oxy))tribenzoic acid (H3BTTB), two solvent‐controlled three‐dimensional (3D) manganese(II) coordination polymers, [Mn3(BTTB)2(H2O)4](H2O)2 (1) and [Mn3(BTTB)2(DMF)2](DMF)2 (2), were synthesized and characterized. Single crystal X‐ray diffraction analysis indicates that in the MnII complexes the BTTB ligands exhibit two coordination modes, which have not been reported previously. Complexes 1 and 2 involve different one‐dimensional (1D) rod‐shaped metal–carboxylate secondary building units (SBUs). The 1D SBUs are further extended to afford two different three‐dimensional (3D) frameworks with similar flu topology via linkage of the BTTB ligands. The results demonstrate that the reaction solvent as well as conformation and coordination mode of BTTB ligands play key roles on the formation of the final framework structures. Additionally, their luminescent properties were investigated.

Synthesis, characterizations and catalytic studies of a new two-dimensional metal−organic framework based on Co–carboxylate secondary building units

A metal–organic framework [Co3(BDC)3(DMF)2(H2O)2] was synthesized and structurally characterized. X-ray single crystal analysis revealed that the framework contains a 2D polymeric chain through coordination of 1,4-benzenedicarboxylic acid linker ligand to cobalt centers. The polymer crystallize in monoclinic P21/n space group with a=13.989(3)Å, b=9.6728(17)Å, c=16.707(3)Å, and Z=2. The polymer features a framework based on the perfect octahedral Co–O6 secondary building units. The catalytic activities of [Co3(BDC)3(DMF)2(H2O)2]n for olefins oxidation was conducted. The heterogeneous catalyst could be facilely separated from the reaction mixture, and reused three times without significant degradation in catalytic activity. Furthermore, no contribution from homogeneous catalysis of active species leaching into reaction solution was detected.

Ionothermal synthesis of a 3D dysprosium–1,4-benzenedicarboxylate framework based on the 1D rod-shaped dysprosium–carboxylate building blocks exhibiting slow magnetization relaxation

Ionothermal reaction of DyCl3·6H2O with 1,4-benzenedicarboxylic acid (H2BDC) in 1-ethyl-3-methylimidazolium bromide (EMIM-Br) leads to a novel compound {(EMIM)[Dy3(BDC)5]}n (1). Compound 1 consists of the extraframework charge-balancing cation [EMIM]+ and the [Dy3(BDC)5]nn− anionic framework with hex topology. The 3D [Dy3(BDC)5]nn− framework is constructed from the 1D rod-shaped Dy–carboxylate secondary building unit wherein the 6-, 8-, and 9-coordinated Dy(III) ions are alternately arranged. Detailed static and dynamic magnetic analysis of 1 revealed that 1 exhibits a slow magnetic relaxation behavior typical of single-molecule magnets (SMMs). Compound 1 displays an anisotropic energy barrier of 39.3 K and a pre-exponential factor τ0 of 2.6 × 10−10 s in the presence of a direct-current field of 2 kOe.

Ionothermal synthesis of a 3D heterometallic coordination polymer based on the rod shaped copper(II)–sodium(I)-carboxylate secondary building units with a pcu topology

Compound [(EEIM)NaCu(phth)2]n (1) (EEIM=1,3-diethylimidazolium and phth=terephthalate) was synthesized by using the mixed ionic liquids of 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM]-BF4 and chiral 1-ethyl-3-methylimidazolium l-lactate as solvent. The sodium(I) ion deriving from the [EMIM]-BF4 with a small amount of Na(I) impurity incorporated into the structure is unprecedented. Compound 1 is a 3D anionic framework based on a unique rod shaped heterometallic copper(II)–sodium(I)-carboxylate secondary building unit, exhibiting a distorted pcu-(412·63) topology. It is interesting that the organic template of [EEIM]+ cation formed from an in situ reaction acting as extraframework charge-balancing species occupies the 1D rhombic channels of the 3D anionic framework. The roles of the ionic liquid in ionothermal synthesis and crystallization of 1 are briefly discussed.

Porous Metalloporphyrinic Frameworks Constructed from Metal 5,10,15,20-Tetrakis(3,5-biscarboxylphenyl)porphyrin for Highly Efficient and Selective Catalytic Oxidation of Alkylbenzenes

We incorporate metal 5,10,15,20-tetrakis(3,5-biscarboxylphenyl)porphyrin (M-H(8)OCPP), for the first time, into porous metal-organic frameworks. The self-assembled porous metalloporphyrinic frameworks [Mn(5)Cl(2)(MnCl-OCPP)(DMF)(4)(H(2)O)(4)]·2DMF·8CH(3)COOH·14H(2)O (ZJU-18; ZJU = Zhejiang University), [Mn(5)Cl(2)(Ni-OCPP)(H(2)O)(8)]·7DMF·6CH(3)COOH·11H(2)O (ZJU-19), and [Cd(5)Cl(2)(MnCl-OCPP)(H(2)O)(6)]·13DMF·2CH(3)COOH·9H(2)O (ZJU-20) are isostructural as revealed by their single X-ray crystal structures. The metalloporphyrin octacarboxylates (M-OCPP) (M = Mn(III)Cl for ZJU-18 and ZJU-20, M = Ni(II) for ZJU-19) are bridged by binuclear and trinuclear metal carboxylate secondary building units to form a 3-periodic, binodal, edge-transitive net with Reticular Chemistry Structure Resource symbol tbo with pore windows of about 11.5 Å and pore cages about 21.3 Å in diameter. The porous nature of these metalloporphyrinic frameworks is further established by sorption studies in which different substrates such as ethanol, acetonitrile, acetone, cyclohexane, benzene, toluene, ethylbenzene, and acetophenone can readily have access to the pores. Their catalytic activities for the oxidation of alkylbenzenes were examined at 65 °C using tert-butyl hydroperoxide as the oxidant. The results indicate that ZJU-18 is much superior to ZJU-19, ZJU-20, and homogeneous molecular MnCl-Me(8)OCPP, exhibiting highly efficient and selective oxidation of ethylbenzene to acetophenone in quantitative >99% yield and a turnover number of 8076 after 48 h.

Structure diversity of a series of new coordination polymers based on a C3-symmetric tridentate ligand with rosette architecture

4,4′,4″-[1,3,5-Benzenetriyltris(carbonylimino)]trisbenzoic acid (H3L), a C3-symmetric ligand, was found to self-assemble into an interesting core-rosette structure driven by intermolecular hydrogen-bonding interactions. Reactions of this ligand with Zn2+, Co2+ and Cd2+ under solvothermal conditions resulted in the formation of four new coordination polymers with interesting structural motifs: [Zn2(L)(OH)(H2O)(DMF)]·DMF·H2O (1), [Co3(L)2(DMF)(H2O)]·DMF·3CH3OH (2), [Co1.5(L)(H2O)(DMF)]·DMF (3), and [Cd1.5(L)(H2O)(DMF)]·DMF (4). Single-crystal structural analysis revealed that complex 1 exhibits a rare example of twofold interpenetrating two-dimensional CdI2-type structure with tetranuclear Zn4(μ3-OH)2(COO)6(H2O)(DMF) serving as secondary building unit (SBU), whereas in 2, the μ3-oxo-tricobalt basic carboxylate SBUs are connected by L3− ligands, leading to a twofold interpenetrating three-dimensional (3,6)-net framework. The isomorphous complexes 3 and 4 each has a (4,4)-grid layered architecture in which the SBU is a linear Co3/Cd3 cluster. The four coordination polymers were all further characterized by IR, thermogravimetric and powder X-ray diffraction (PXRD).

Syntheses, Crystal Structures, and Gas Storage Studies in New Three-Dimensional 5-Aminoisophthalate Praseodymium Polymeric Complexes

The hydrothermal reaction of 5-aminoisophthalic acid and praseodymium oxide in different acids results in two new praseodymium coordination polymers, {Pr(2)(aip)(3)(H(2)O)(2) x 3 H(2)O}(n) (1) and {Pr(2)(Haip)(2)(aip)(NO(3))(2) x 8 H(2)O}(n) (2) (aip = 5-aminoisophthalate). Complexes 1 and 2 are two distinct three-dimensional metal-organic frameworks constructed from the linkage of rod-shaped praseodymium carboxylate secondary building units and phenyl rings. Both dehydrated coordination frameworks are estimated using a computational method based on Connolly's algorithm, indicating that dehydrated compound 1 cannot host molecules other than water molecules or He, whereas dehydrated compound 2 is able to host molecules with kinetic radii as big as 2.3 A. The potential specific accessible surface of this compound is 792 m(2) g(-1). Meanwhile, N(2) sorption measurements reveal that dehydrated compound 2 having a high 230 cm(3)/g (287 mg/g) N(2) storage capacity at 77 K and 1 atm is in fairly good agreement with our calculation results. Moreover, powder X-ray diffraction measurement results demonstrated that the stable channels of dehydrated compound 2 can reversibly host other small solvent molecules (e.g., water, methanol, and ethanol) and grand canonical Monte Carlo simulation is applied to predict its hydrogen storage capacity.

Phase Selection and Discovery among Five Assembly Modes in a Coordination Polymerization

The combination of zinc(II) nitrate with 1,3,5-(triscarboxyphenyl)benzene (H 3BTB) leads to five different microporous coordination polymers (MCPs). Two of these were previously known (MOF-177 and MOF-39), whereas polymer-induced heteronucleation was used in the discovery of three phases that have not been previously reported ( Zn/BTB ant, Zn/BTB tsx, and Zn/BTB dia). Modification of crystallization conditions allows for the bulk-scale synthesis of each of these MCPs. Zn/BTB ant and Zn/BTB tsx are each interpentrated 6,3-connected nets composed of the basic zinc carboxylate secondary building unit (SBU) and the tritopic linker BTB. The underlying noninterpenetrated net of Zn/BTB ant is derived for the net of anatase, whereas that of Zn/BTB tsx is the previously unreported "tsx" framework. Zn/BTB dia consists of an underlying diamondoid net in which four linear, trinuclear zinc hourglass SBUs are arranged about a central mu 4-oxo anion as the tetrahedral unit in the net and BTB further links the hourglass SBUs. Zn/BTB ant, Zn/BTB tsx, and MOF-177 are here defined as polymorphic frameworks in that each is composed of the same SBU and linker but differ in topology and thus pore structure. These frameworks may be called a polyreticular series by analogy to several reported isoreticular series. The effect of linker-linker interactions are discussed.

Metal−Organic Framework Based on a Trinickel Secondary Building Unit Exhibiting Gas-Sorption Hysteresis

An interpenetrating microporous metal-organic framework based on a mu3-oxotrinickel basic carboxylate secondary building unit has been synthesized and structurally characterized. It exhibits pronounced gas-sorption hysteresis and selective adsorption of carbon dioxide over methane.

An inclined interpenetrating heteropolynuclear polymer with unusual propagation of metal carboxylate secondary building units by both carboxylate and pyridyl bridging ligands

The objective of this paper is to describe an unusual coordination polymer, M4(μ4-O)(bipy)(m-BDC)3 (sM4=Zn2.36 Co1.64, bipy=4,4′-bipyridine, m-H2BDC=1,3-benzenedicarboxylic acid) (1), which has been hydrothermally synthesised and characterized by single-crystal X-ray diffraction, XRPD, IR, TGA, ICP, atomic absorption, and element analysis. 1 crystallizes in the P42/mnm space group and contains a M4O(O2C)6 secondary building unit (SBU) with an inclined interpenetrated (4,4) topology, and is a rare combination of the two most successful approaches to coordination polymer design: generation of metal carboxylate SBUs and the use of pyridyl donor bridges. Moreover, complex 1 exhibits intense fluorescence at about 424nm (λex=312nm) in the solid state.

Microporous Metal–Organic Framework Constructed from Heptanuclear Zinc Carboxylate Secondary Building Units

A novel, three-dimensional, noninterpenetrating microporous metal-organic framework (MOF), [Zn7O2(pda)5(H2O)2]5 DMF4 EtOH 6 H2O (1) (H2PDA=p-phenylenediacrylic acid, DMF=N,N-dimethylformamide, EtOH=ethanol), was synthesized by constructing heptanuclear zinc carboxylate secondary building units (SBUs) and by using rigid and linear aromatic carboxylate ligands, PDA. The X-ray crystallographic data reveals that the seven zinc centers of 1 are held together with ten carboxylate groups of the PDA ligands and four water molecules to form a heptametallic SBU, Zn7O4(CO2)10, with dimensions of 9.8 x 9.8 x 13.8 A3. Furthermore, the heptametallic SBUs are interconnected by PDA acting as linkers, thereby generating an extended network with a three-dimensional, noninterpenetrating, intersecting large-channel system with spacing of about 17.3 A. As a microporous framework, polymer 1 shows adsorption behavior that is favorable towards H2O and CH3OH, and substantial H2 uptake. In terms of the heptanuclear zinc carboxylate SBUs, polymer 1 exhibits interesting photoelectronic properties, which would facilitate the exploration of new types of semiconducting materials, especially among MOFs containing multinuclear metal carboxylate SBUs.