DABCO-functionalized metal–organic framework bearing a C2h-symmetric terphenyl dicarboxylate linker

Fluorescent and Catalytic Properties of a 2D Lamellar Zn Metal-Organic Framework with sql Network Structure

A two-dimensional (2D) lamellar Zn metal-organic framework (Zn-MOF, 1) with a fluorescent 1,6-di(pyridin-3-yl)pyrene (3-DPPy) and 1,4-benzenedicarboxylate (BDC2-) bridging linkers was prepared and structurally characterized. The chemical formula of 1 is [Zn(μ-3-DPPy)(μ-BDC)]n. The mononuclear Zn(II) ion, acting as a node, is tetrahedrally coordinated with two 3-DPPy and two BDC linkers. The coordination environment of Zn(II) is a distorted tetrahedral geometry. The Zn-MOF is the sql network structure based on topology analysis. The undulated 2D sheets of 1 tightly pack together to form a lamellar structure. The pyrene moieties are parallelly oriented to each other. The Zn-MOF is not porous, possibly because the mononuclear Zn(II) node did not form cluster-based secondary building units due to the less symmetric 3-DPPy. The steady-state fluorescence measurements indicate that the fluorescence signal of the 1 is slightly blue-shifted compared to the free 3-DPPy in the solid state. The excimer emission band at 463 nm for crystalline 3-DPPy is shifted to 447 nm for 1. The value of 447 nm is also a blue-shift value compared to nonsubstituted pyrene crystals (470 nm). Despite its nonporosity, the surface Lewis acidic sites of 1 could catalyze the transesterification of esters. Surface defect sites are responsible for this catalytic activity.

Functionalization of zirconium-based metal-organic frameworks for gas sensing applications

The functionalization and incorporation of noble metals in metal-organic frameworks have been widely used as efficient methods to enhance their applicability. Herein, a sulfone-functionalized Zr-MOF framework labeled Zr-BPDC-SO₂ (BPDC-SO₂ =dibenzo[b,d]-thiophene-3,7-dicarboxylate 5,5-dioxide) and its Pd-embedded composite were efficiently synthesized by adjusting their functional groups. The obtained compounds were characterized to assess their potential for gas sensing applications. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area measurements, and thermogravimetric analysis were employed to characterize the new sensor materials. The gas sensing properties of the novel functionalized sensor materials were systematically investigated under various temperature, concentration, and gas type conditions. Owing to the strong hydrogen bonds of the sulfonyl groups and Zr₆ clusters in the framework with the hydroxyl groups of ethanol, Zr-BPDC-SO₂ emerged as an effective sensor for ethanol detection. In addition, Pd@Zr-BPDC-SO₂ exhibited efficient hydrogen sensing performance, in terms of sensor dynamics and response. More importantly, the material showed a higher sensing response to hydrogen than to other gases, highlighting the important role of Pd in the Zr-MOF-based hydrogen sensor. The results of the sensing tests carried out in this study highlight the promising potential of the present materials for practical gas monitoring applications.

A tryptophan-based copper(ii) coordination polymer: catalytic activity towards Suzuki–Miyaura cross-coupling reactions

An unusual tryptophan coordination mode with copper(ii) wherein l-tryp is coordinated through the carboxylate and amine groups. A heterogeneous catalyst for the Suzuki cross-coupling reaction with ∼98% yield under normal reaction conditions.

Conversion from Heterometallic to Homometallic Metal-Organic Frameworks

Two new heterometallic metal-organic frameworks (MOFs), LnZnTPO 1 and 2, and two homometallic MOFs, LnTPO 3 and 4 (Ln=Eu for 1 and 3, and Tb for 2 and 4; H₃ TPO=tris(4-carboxyphenyl)phosphine oxide) were synthesized, and their structures and properties were analyzed. They were prepared by solvothermal reaction of the C₃ -symmetric ligand H₃ TPO with the corresponding metal ion(s) (a mixture of Ln³⁺ and Zn²⁺ for 1 and 2, and Ln³⁺ alone for 3 and 4). Single-crystal XRD (SXRD) analysis revealed that 1 and 3 are isostructural to 2 and 4, respectively. TGA showed that the framework is thermally stable up to about 400 °C for 1 and 2, and about 450 °C for 3 and 4. PXRD analysis showed their pore-structure distortions without noticeable framework-structure changes during drying processes. The shapes of gas sorption isotherms for 1 and 3 are almost identical to those for 2 and 4, respectively. Solvothermal immersion of 1 and 2 in Tb³⁺ and Eu³⁺ solutions resulted in the framework metal-ion exchange affording 4 and 3, respectively, as confirmed by photoluminescence (PL), PXRD, IR, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and energy-dispersive X-ray (EDX) analyses.

Hybrid nanomaterials for asymmetric purposes: green enantioselective C–C bond formation by chiralization and multi-functionalization approaches

We present a simple and novel strategy for synthesis of a MOF-based chiral multi-functional hybrid nanomaterial through chiralization and multi-functionalization approaches for asymmetric purposes.

Framework disorder and its effect on selective hysteretic sorption of a T-shaped azole-based metal-organic framework

Metal-organic frameworks with highly ordered porosity have been studied extensively. In this paper, the effect of framework (pore) disorder on the gas sorption of azole-based isoreticular Cu(II) MOFs with rtl topology and characteristic 1D tubular pore channels is investigated for the first time. In contrast to other isoreticular rtl metal-organic frameworks, the Cu(II) metal-organic framework based on 5-(1H-imidazol-1-yl)isophthalate acid has a crystallographically identifiable disordered framework without open N-donor sites. The framework provides a unique example for investigating the effect of pore disorder on gas sorption that can be systematically evaluated. It exhibits remarkable temperature-dependent hysteretic CO2 sorption up to room temperature, and shows selectivity of CO2 over H2, CH4 and N2 at ambient temperature. The unique property of the framework is its disordered structure featuring distorted 1D tubular channels and DMF-guest-remediated defects. The results imply that structural disorder (defects) may play an important role in the modification of the performance of the material.

Catalytic Space Engineering of Porphyrin Metal-Organic Frameworks for Combined CO2 Capture and Conversion at a Low Concentration

Porous porphyrin metal-organic frameworks (PMOFs) provide promising platforms for studying CO₂ capture and conversion (C3) owing to their versatility in photoelectric, catalytic, and redox activities and porphyrin coordination chemistry. Herein, we report the C3 application of two PMOFs by engineering the coordination space through the introduction of two catalytic metalloporphyrins doped with rhodium or iridium, Rh-PMOF-1 and Ir-PMOF-1, both of which can serve as heterogeneous catalysts for the chemical fixation of CO₂ into cyclic carbonates with yields of up to 99 %. Remarkably, the catalytic reactions can effectively proceed under low CO₂ concentrations and high yields of 83 % and 73 % can be obtained under 5 % CO₂ in the presence of Rh-PMOF-1 and Ir-PMOF-1, respectively. The synergistic effect of the metalloporphyrin ligand and the Zr₆ O₈ cluster, in combination with the CO₂ concentration effect from the pore space, might account for the excellent catalytic performance of Rh-PMOF-1 under low CO₂ concentration. Recycling tests of Rh-PMOF-1 show negligible loss of catalytic activity after 10 runs.

In6S7 nanoparticle-embedded and sulfur and nitrogen co-doped microporous carbons derived from In(tdc)2 metal-organic framework

Indium sulfide nanoparticle (NP)-embedded microporous carbons co-doped with S- and N-dopants are easily prepared by a direct carbonization of the as-prepared In(iii)-based metal-organic framework (In-MOF), [Et₂NH₂][In(tdc)₂]·DEF, containing ditopic S-containing 2,5-thiophenedicarboxylate (tdc^2-) bridging linkers as a potential source of S-dopant. The charge on the anionic framework of [In(tdc)₂]^- is balanced by Et₂NH₂⁺, which is also a potential N-dopant. Simultaneous embedding of In-based NPs, S-, and N-co-doping is achieved in a simple single step carbonization of In-MOF. Three porous carbon materials (PCMs), PCM-700, PCM-800, and PCM-900, are obtained from the carbonization of In-MOF at 700, 800, and 900 °C, respectively. The gas sorption analysis indicates them as good CO₂ sorbents. The photocatalytic degradation of methyl orange by PCMs under visible light irradiation is also effectively operable owing to the photocatalytically active semiconducting indium sulfide NP with a small bandgap. The main component of indium sulfide NPs is revealed as In₆S₇ based on the powder X-ray diffraction pattern. Small amounts of metallic In and In₂S₃ are also observed. The specific capacitances of PCMs are also estimated from the galvanostatic charge/discharge curves. PCM-900 exhibits the highest gravimetric specific capacitance of 99.0 F g^-1 at a current density of 0.05 A g^-1.

Selective carbon dioxide sorption by a new breathing three-dimensional Zn-MOF with Lewis basic nitrogen-rich channels

A CO₂ selective dynamic three-dimensional MOF, [Zn₂(μ₄-3,3′-PDBA)₂(μ₂-bpa)]₃·(DMF)₅(H₂O)₁₃, shows an unusual 3(2 + 1)-fold interpenetrated structure and phenomenal hysteretic behavior in CO₂ sorption.

Selective carbon dioxide sorption and heterogeneous catalysis by a new 3D Zn-MOF with nitrogen-rich 1D channels

We prepared a new C_2h-symmetric bridging ligand, 3,3′-(pyrazine-2,5-diyl)dibenzoic acid (3,3′-PDBA), through a Suzuki coupling reaction. 3,3′-PDBA contains a central pyrazine ring instead of the phenyl ring of 3,3′-terphenyldicarboxylic acid (3,3′-TPDC). Despite the geometrical similarity of the two bridging ligands, the reaction between Zn(NO₃)₂·6H₂O and 3,3′-PDBA in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) yielded a structurally different Zn-based metal-organic framework (Zn-MOF). The Zn-MOF, [Zn₂(3,3′-PDBA)₂(DABCO)_1.5]·2DMF·H₂O, had two-dimensional (2D) layers, and the interlocked 2D layers formed a porous 3D framework. Interestingly, one of the two available N atoms of DABCO remained intact. The uncoordinated N atoms of the dangling DABCO ligand and the pyrazinyl N atoms of the 3,3′-PDBA bridging ligand were fully exposed toward the 1D channels. Therefore, the 1D channels represented a highly nitrogen-rich environment. Gas sorption analysis indicated that the Zn-MOF was selective for adsorption of CO₂ at 196 K over N₂ (77 K) and H₂ (77 K). The exceptionally high zero surface coverage heat of CO₂ adsorption (Q_st = 79.5 kJ mol⁻¹) was attributable to the openly accessible multiple Lewis basic sites in the nitrogen-rich 1D channels. Zn-MOF also showed good Lewis base catalytic activities in three model aldol-type reactions with good recyclability due to chemically accessible 3° amine sites.

Gas adsorption in Mg-porphyrin-based porous organic frameworks: A computational simulation by first-principles derived force field

A novel type of porous organic frameworks, based on Mg-porphyrin, with diamond-like topology, named POF-Mgs is computationally designed, and the gas uptakes of CO₂ , H₂ , N₂ , and H₂ O in POF-Mgs are investigated by Grand canonical Monte Carlo simulations based on first-principles derived force fields (FF). The FF, which describes the interactions between POF-Mgs and gases, are fitted by dispersion corrected double-hybrid density functional theory, B2PLYP-D3. The good agreement between the obtained FF and the first-principle energies data confirms the reliability of the FF. Furthermore our simulation shows the presence of a small amount of H₂ O (≤ 0.01 kPa) does not much affect the adsorption quantity of CO₂ , but the presence of higher partial pressure of H₂ O (≥ 0.1 kPa) results in the CO₂ adsorption decrease significantly. The good performance of POF-Mgs in the simulation inspires us to design novel porous materials experimentally for gas adsorption and purification. © 2017 Wiley Periodicals, Inc.

Metal-Organic Frameworks for Heterogeneous Basic Catalysis

Great attention has been given to metal-organic frameworks (MOFs)-derived solid bases because of their attractive structure and catalytic performance in various organic reactions. The extraordinary skeleton structure of MOFs provides many possibilities for incorporation of diverse basic functionalities, which is unachievable for conventional solid bases. The past decade has witnessed remarkable advances in this vibrant research area; however, MOFs for heterogeneous basic catalysis have never been reviewed until now. Therefore, a review summarizing MOFs-derived base catalysts is highly expected. In this review, we present an overview of the recent progress in MOFs-derived solid bases covering preparation, characterization, and catalytic applications. In the preparation section, the solid bases are divided into two categories, namely, MOFs with intrinsic basicity and MOFs with modified basicity. The basicity can originate from either metal sites or organic ligands. Different approaches used for generation of basic sites are included, and each approach is described with representative examples. The fundamental principles for the design and fabrication of MOFs with basic functionalities are featured. In the characterization section, experimental techniques and theoretical calculations employed for characterization of basic MOFs are summarized. Some representive experimental techniques, such as temperature-programmed desorption of CO₂ (CO₂-TPD) and infrared (IR) spectra of different probing molecules, are covered. Following preparation and characterization, the catalytic applications of MOFs-derived solid bases are dealt with. These solid bases have potential to catalyze some well-known "base-catalyzed reactions" like Knoevenagel condensation, aldol condensation, and Michael addition. Meanwhile, in contrast to conventional solid bases, MOFs show some different catalytic properties due to their special structural and surface properties. Remarkably, characteristic features of MOFs-derived solid bases are described by comparing with conventional inorganic counterparts, keeping in mind the current opportunities and challenges in this field.

Construction of 3D homochiral metal–organic frameworks (MOFs) of Cd(ii): selective CO2adsorption and catalytic properties for the Knoevenagel and Henry reaction

Syntheses of two new homochiral, 3D metal–organic frameworks (MOFs) of Cd(ii) and the selective CO₂adsorption and catalytic properties of1has been demonstrated.

Synthesis, structure and properties of an octahedral dinuclear-based Cu12 nanocage of trimesoyltri(l-alanine)

We report here a Mo₆C1₈⁴⁺-like dinuclear-based octahedral nanocage, presenting antiferromagnetic interactions between the Cu(ii) ions and nice selectivity on gas adsorption.

One-dimensional Cu(II) coordination polymers containing C2h-symmetric 1,1':4',1''-terphenyl-3,3'-dicarboxylate linkers

Two new one-dimensional Cu(II) coordination polymers (CPs) containing the C2h-symmetric terphenyl-based dicarboxylate linker 1,1':4',1''-terphenyl-3,3'-dicarboxylate (3,3'-TPDC), namely catena-poly[[bis(dimethylamine-κN)copper(II)]-μ-1,1':4',1''-terphenyl-3,3'-dicarboxylato-κ(4)O,O':O'':O'''] monohydrate], {[Cu(C20H12O4)(C2H7N)2]·H2O}n, (I), and catena-poly[[aquabis(dimethylamine-κN)copper(II)]-μ-1,1':4',1''-terphenyl-3,3'-dicarboxylato-κ(2)O(3):O(3')] monohydrate], {[Cu(C20H12O4)(C2H7N)2(H2O)]·H2O}n, (II), were both obtained from two different methods of preparation: one reaction was performed in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar. Both reactions afforded crystals of different colours, i.e. violet plates for (I) and blue needles for (II), both of which were analysed by X-ray crystallography. The 3,3'-TPDC bridging ligands coordinate the Cu(II) ions in asymmetric chelating modes in (I) and in monodenate binding modes in (II), forming one-dimensional chains in each case. Both coordination polymers contain two coordinated dimethylamine ligands in mutually trans positions, and there is an additional aqua ligand in (II). The solvent water molecules are involved in hydrogen bonds between the one-dimensional coordination polymer chains, forming a two-dimensional network in (I) and a three-dimensional network in (II).

Exceptional CO2 working capacity in a heterodiamine-grafted metal-organic framework

An amine-functionalized metal-organic framework (MOF), dmen-Mg2(dobpdc) (dmen = N,N-dimethylethylenediamine), which contains a heterodiamine with both primary and tertiary amines, was prepared via a post-synthetic method. This material exhibits a significant selectivity factor for CO2 over N2 that is commensurate with top-performing MOFs. It is remarkable that the solid is fully regenerated under vacuum or flowing Ar at low desorption temperatures, and following this can take up CO2 at more than 13 wt%. An exceptionally high working capacity is achieved at low regeneration temperatures and after exposure to humid conditions, which are important parameters for a real post-combustion CO2 capture process.

CO2 selective 1D double chain dipyridyl-porphyrin based porous coordination polymers

Two CO₂ selective 1D double chain dipyridyl-porphyrin-based porous coordination polymers, Co₃(DPyP)₃·4DMF (I) and Zn₃(DPyP)₃·2DMF·4H₂O (II) are prepared from thermal reactions of MnCl(DPyP) with Co^II and Zn^II ions in DMF.

Amide and N-oxide functionalization of T-shaped ligands for isoreticular MOFs with giant enhancements in CO2 separation

N-Oxidization of a T-shaped ligand has proven to be an effective way to enhance CO₂ adsorption enthalpy and selectivity in porous MOFs for the first time.

Size-dependent catalysis by DABCO-functionalized Zn-MOF with one-dimensional channels

Lewis basic DABCO-functionalized 3D-like metal-organic framework, Zn-MOF, catalyzes nitroaldol (Henry) reaction of 4-nitrobenzaldehyde with nitroalkanes in a size-dependent manner. Small nitroalkanes give rise to higher conversion than larger ones. This MOF-based heterogeneous catalyst is very robust and can be recycled several times without losing its activity.

Bio-functionalization of metal-organic frameworks by covalent protein conjugation

Bioconjugation of functional proteins onto metal-organic frameworks (MOFs) has been achieved using activation of pendent linking groups of the organic linkers on the surface of MOFs. Fluorescent microscopy revealed successful conjugation of an enhanced fluorescent protein onto MOFs. In addition, Candida-antarctica-lipase-B-conjugated MOFs showed no loss of enantioselectivity and activity in transesterification of (±)-1-phenylethanol.

catena-Poly[[bis-(dimethyl-ammonium) [cadmate(II)-bis-(μ-1,1':4',1''-terphenyl-3,3''-dicarboxyl-ato)]] dimethyl-formamide disolvate]

In the title compound, {(C(2)H(8)N)(2)[Cd(C(20)H(12)O(4))(2)]·2C(3)H(7)NO}(n), the Cd(II) ion lies on a twofold rotation axis and is in a distorted octa-hedral CdO(6) environment, defined by four O atoms of two μ(2)-coordinated 1,1':4',1''-terphenyl-3,3''-dicarboxyl-ate (DCT) ligands and two O atoms of two μ(1)-coordinated DCT ligands. Both types of DCT ligands act as bridging, forming a one-dimensional polymeric structure propagating parallel to [10].