Biphenyldicarboxylic Acid Research Articles

Synthesis and characterization of biphenyldicarboxylic acid-modified poly(1,4-cyclohexylenedimethylene terephthalate) copolyesters

A new copolyesters of poly(1,4-cyclohexylenedimethylene terephthalate-co-4,4’-biphenydicarboxylate) (PCTB) with different compositions were synthesized from terephthalic acid, 1,4-cyclohexanedimethanol and 4,4’-biphenyldicarboxylic acid (BDA) via esterification-polycondensation reaction. The synthesized copolyesters were analyzed by 1H-NMR, 13C-NMR, FT-IR, GPC, intrinsic viscosity, DSC, TGA and tensile testing, respectively. The 1H-NMR, 13C-NMR and FT-IR results verify the successful introduction of BDA into poly(1,4-cyclohexylenedimethylene terephthalate (PCT) chains. The introduction of BDA into PCT chains can effectively lower the melting point of PCT, making it easier to process. The glass transition temperature of PCTB is higher than 103 °C and its thermal stability is better than that of PCT. The rheological tests confirm the enhanced melting stability of PCT after introducing BDA into PCT chains. Furthermore, the PCTB, which owns the comparable mechanical properties to PCT, is a tough polymer with the higher Young’s modulus (above 230 MPa), the higher tensile strength (above 41 MPa) and the higher elongation at break (above 159%).

Crystallographic Visualization of a Guest-Induced Solar-Driven Cycloaddition Reaction Based on a Recyclable Nonporous Coordination Polymer.

Stimuli-responsive solids with adjustable photophysical properties are particularly attractive because they can be used as smart materials in anticounterfeiting, information storage, holographic imaging, and other fields. Herein, we report a unique nonporous coordination polymer, {[Ag(3,3'-dpe)](2,2'-Hbpdc)}n (1; 3,3'-dpe = 1,2-dipyridin-3-ylethene and 2,2'-H2bpdc = 2,2'-biphenyldicarboxylic acid), that can convert to an extremely photoreactive compound, 1·H2O·MeCN (MeCN = acetonitrile), through guest capture. Upon irradiation of sunlight, 1·H2O·MeCN can transform to {[Ag(3,3'-tpcb)0.5](2,2'-Hbpdc)(H2O)(MeCN)}n (2·H2O·MeCN; 3,3'-tpcb = 1,2,3,4-tetrapyridin-3-ylcyclobutane). 2·H2O·MeCN can lose its solvent molecules to form 2 and further return to 1 at high temperature. Accompanied by direct visualization based on multistep single-crystal-to-single-crystal conversions, the recyclable crystalline solid exhibits remarkable fluorescence changes, which makes it a supramolecular switch for application in multiple anticounterfeiting.

Functionalized Zr-UiO-67 metal-organic frameworks: Structural landscape and application

• Structural classification of functionalized and unfunctionalized UiO-67 MOFs have been investigated. • The structural landscape in UiO-67 is based on three linkers bpdc, bipydc, and ppydc. • The metalation of linkers within MOFs have been reviewed and discussed. • The recent advances on application of the UiO-67-based MOFs was investigated. UiO based metal-organic frameworks (MOFs) have attracted much attention of many scientists among the large family of Zirconium MOFs. UiO-series including UiO-66, -67 and -68 which possesses high stability, tunability, porosity, and functions, are rapidly extending field in metal-organic frameworks since 2008. This progress in this family of MOFs, extended to the ability of linkers to be functionalized and led to generate new crystalline materials with desired properties and applications. This review presents comprehensively all of the reported functionalized and unfunctionalized UiO-67 MOFs in terms of structural classification. The overall framework of UiO- based MOF constructed from three different linkers including 4,4′-biphenyl dicarboxylic acid (bpdc), 2,2′-bipyridine-5,5′-dicarboxylic acid (bipydc) and 2-phenylpyridine-5,4′-dicarboxylic acid (ppydc). Also, the metalation of these linkers within MOFs investigated. Furthermore, a brief study on the application of the UiO-67-based MOFs was conducted.

High-performance lanthanum-based metal–organic framework with ligand tuning of the microstructures for removal of fluoride from water

Excess fluoride in water poses a threat to ecology and human health, which has attracted global attention. In this study, a series of lanthanum-based metal–organic frameworks (La-MOFs) were synthesized by varying the organic ligands (i.e., terephthalic acid (BDC), trimesic acid (BTC), biphenyl-4,4-dicarboxylic acid (BPDC), 2,5-dihydroxyterephthalic acid (BHTA), and 1,2,4,5-benzenetetracarboxylic acid (PMA)) to control the microscopic structure of the MOFs and subsequently apply them for the removal of fluoride in water. The maximum capture capacities of La-BTC, La-BPDC, La-BHTA, La-PMA, and La-BDC at 298 K are 105.2, 125.9, 145.5, 158.9, and 171.7 mg g−1, respectively. The adsorption capacity is greater than most reported adsorbents. The adsorption isotherms of La-MOFs for fluoride are well fit to the Langmuir isotherm model. In addition, the adsorption kinetics of La-BTC, La-BPDC, La-BHTA, La-PMA, and La-BDC follows the pseudo-second-order kinetic model, and the kinetic rate-limiting step of adsorption is chemical adsorption. Thermodynamics revealed that temperature is favorable for the adsorption of fluoride. Meanwhile, La-BTC, La-BPDC, La-BHTA, La-PMA, and La-BDC are suitable for the removal of fluoride in a relatively wide pH range (4.0–9.0). Simultaneously, from X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis, electrostatic attraction and ligand exchange are identified as the main action mechanisms for the adsorption of fluoride of La-MOFs. The prepared La-MOFs are used as efficient adsorbents for removal of fluoride in actual water, indicating that they have great potential in removing fluoride in real and complex environmental water. This work provides a new strategy for designing adsorbents with adjustable microstructure and expected function to effectively recover fluorosis in water.

Emission ratiometric sensing for peroxyacetic acid using the codoping of Tb(III) and Eu(III) in MOF matrix: Energy competing between RE(III) via electron-rich ligands

The determination and quantification of oxidants related with chemical engineering and chemical industry is always an important issue for modern analytical chemistry. In this paper, a series of electron-rich ligands were synthesized and confirmed by their single crystals. Their cyclic voltammetry curves suggested that they were sensitive towards oxidants. These electron-rich ligands were coordinated with Eu(III) and Tb(III) ions and doped into a MOF (metal-organic-framework) supporting matrix of bio-MOF-1. Here bio-MOF-1 denoted [Zn8(ad)4(BPDC)6O·2(Me2NH2)+]·G, ad = adenine, BPDC = 4,4′-biphenyl dicarboxylic acid, G = N,N-dimetylformamide and water. The resulting composite sample was analyzed and confirmed with SEM, XRD, N2 adsorption/desorption and ICP measurement. It was found that there was an energy competing between Eu(III) and Tb(III) emissive centers. The Eu(III) emission intensity was decreased with increasing peracitic acid concentration, but the Tb(III) emission intensity was increased, showing ratiometric sensing signal. Linear sensing behavior was observed with sensitivity as high as 8.01 and response time of ~93 s. The sensing mechanism was revealed as the energy competing between Eu(III) and Tb(III) ions. In the absence of peracitic acid, the dominant energy transfer was a Eu(III)-based one, showing strong Eu(III) emission and weak Tb(III) emission. After adding peracitic acid, ligand energy transfer for Tb(III) was enhanced but that for Eu(III) was compromised, leading to quenched Eu(III) emission and increased Tb(III) emission. A good sensing selectivity was observed and attributed to the protecting and buffering effect of supporting matrix bio-MOF-1.

Structure, Luminescent Sensing and Proton Conduction of a Boiling-Water-Stable Zn(II) Metal-Organic Framework.

A novel Zn(II) metal-organic framework [Zn4O(C30H12F4O4S8)3]n, namely ZnBPD-4F4TS, has been constructed from a fluoro- and thiophenethio-functionalized ligand 2,2′,5,5′-tetrafluoro-3,3′,6,6′-tetrakis(2-thiophenethio)-4,4′-biphenyl dicarboxylic acid (H2BPD-4F4TS). ZnBPD-4F4TS shows a broad green emission around 520 nm in solid state luminescence, with a Commission International De L’Eclairage (CIE) coordinate at x = 0.264, y = 0.403. Since d10-configured Zn(II) is electrochemically inert, its photoluminescence is likely ascribed to ligand-based luminescence which originates from the well-conjugated system of phenyl and thiophenethio moieties. Its luminescent intensities diminish to different extents when exposed to various metal ions, indicating its potential as an optical sensor for detecting metal ion species. Furthermore, ZnBPD-4F4TS and its NH4Br-loaded composite, NH4Br@ZnBPD-4F4TS, were used for proton conduction measurements in different relative humidity (RH) levels and temperatures. Original ZnBPD-4F4TS shows a low proton conductivity of 9.47 × 10−10 S cm−1 while NH4Br@ZnBPD-4F4TS shows a more than 25,000-fold enhanced value of 2.38 × 10−5 S cm−1 at 40 °C and 90% RH. Both of the proton transport processes in ZnBPD-4F4TS and NH4Br@ZnBPD-4F4TS belong to the Grotthuss mechanism with Ea = 0.40 and 0.32 eV, respectively.

Flexible Microporous Copper(II) Metal-Organic Framework toward the Storage and Separation of C1-C3 Hydrocarbons in Natural Gas.

A flexible and robust microporous copper(II) metal-organic framework (MOF) based on a methyl-functionalized ligand, namely, [Cu3(μ3-OH)2(L)2(DMF)] (LIFM-ZZ-1; L = 2,2'-dimethyl-4,4'-biphenyldicarboxylic acid and DMF = N,N-dimethylformamide), was constructed. Its sorption performance for the separation of CH4, C2H6, and C3H8 was investigated. LIFM-ZZ-1 showed a breathing behavior that led to a transition between large- and narrow-pore states. The sample also showed outstanding water stability. Gas adsorption experiments revealed that desolvated LIFM-ZZ-1 exhibited higher adsorption capacities for C2H6 and C3H8 (2.80 and 4.06 mmol·g-1) than for CH4 (0.39 mmol·g-1) at 298 K and 1 bar. Breakthrough experiments showed that a CH4/C2H6/C3H8 mixture was completely separated at 298 K, demonstrating the promising potential applications of this material for separating low contents of C2/C3 hydrocarbons from natural gas.

Boosting Ammonia Uptake within Metal–Organic Frameworks by Anion Modulating Strategy

Ammonia with toxic and corrosive features needs advanced protective materials and removal tools, although it is a vital component in human food supply processes. So, to satisfy these requirements, materials with high adsorption capacity and affinity for ammonia should be developed. The present research has been focused on a series zinc-based metal-organic frameworks (MOF) containing mixed ligands, biphenyl dicarboxylic acid (BPDA) and tris(4-(4H-1,2,4-triazol-4-yl)phenyl)amine (TTPA), which are modulated by different anions including CH3COO-, CF3COO-, and CF3SO3-. Ammonia uptake capacity was measured via static and dynamic conditions under 50% relative humidity. Among all compounds, CF3SO3- anion could enhance the ammonia uptake capacity of MOFs up to 177.85 and 349 mg/g during static and breakthrough measurements, respectively, so that 83.30% of the total uptake capacity (at P/Po = 1.0 and 298 K) was achieved at low relative pressure range (up to 0.1). The isosteric heats of ammonia adsorption on PFC-27 and derivatives were calculated in the range of 7.03-10.16 kJ mol-1 so that they increased upon CF3SO3-, CF3COO-, and CH3COO- ion incorporation. This is potentially beneficial for enhanced ammonia adsorption. Interestingly, adsorption capacities were retained with only slight changes after five cycles and three regeneration temperatures, 25 °C, 60 °C, and 120 °C, under vacuum. The special affinity for NH3 adsorption and MOF phase stability after desorption is clearly proved by FTIR spectra and PXRD analysis, respectively. Generally, the results suggest that ion insertion modification is an efficient strategy for enhancement of MOF adsorption performance.

Tunable electrochemical behavior of dicarboxylic acids anchored Co-MOF: Sensitive determination of rutin in pharmaceutical samples

Rutin (RT) also known as vitamin P, is an electroactive flavanoid mainly found in plants. It is generally applied as a clinical drug, Chinese traditional medicine and consumed as a supplement and act as a healthy collagen. Consumption of RT as supplement associated with some side effects and certain people has allergy towards RT. Therefore, it is meaningful to develop a fast, simple and reliable method to detect RT to avoid health risks. This paper describes the facile synthesis of Co-MOF using 1,4-benzenedicarboxylic acid (BDC) and biphenyl-4,4-dicarboxylic acid (BPDC) as ligands through solvothermal method. The XRD patterns and FT-IR spectra confirm the formation of Co-BDC and Co-BPDC MOFs. Moreover, the SEM images revealed that the Co-BDC MOF possesses a stacked layer of MOF while Co-BPDC MOF shows a flower-like MOF. The Co-BDC and Co-BPDC MOFs were fabricated on GC electrode for the sensitive determination of RT. The ligands with different chain lengths in the MOFs have influenced the interaction of RT with the MOF. The Co-BPDC-MOF/GCE exhibited an excellent electrocatalytic activity than the Co-BDC-MOF/GCE and the fabricated electrode was successfully utilized for the determination of RT in pharmaceutical samples. The fabricated sensor exhibited the limit of detection of 0.03 µM (S/N = 3) and the superior sensitivity of 781.43 µA/mM/cm2 in the linear range detection of 0.5 – 1000 µM RT with excellent repeatability, reproducibility, and good anti-interference ability.

A Cobalt-Organic Framework with Sensitive Detection of Fe3+, Cr2O72–, and CrO42– Ions in Water

A six-coordinated 3D metal–organic framework (MOF), namely, [Co(BPDC)(3-bpdb)(H2O)2]n (1) (H2BPDC = 4,4′-biphenyldicarboxylic acid, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene) was purposefully constructed and characterized by single-crystal XRD, IR, elemental analyses, PXRD, SEM, and TGA. Crystal structural analysis revealed that the complex consists of a cds-type three-fold interpenetrated framework. Hirshfeld surface analysis yielded details of the surface characteristics of 1. Significant O−H···O hydrogen bonding interactions, which could promote the stability of the framework, were found is extremely stable in aqueous solution and can resist acids and bases over an extensive pH range of 2–13. 1 shows brilliant fluorescent emission in the solid state and in aqueous solution. Fluorescence titration, cyclic, and anti-interference experiments demonstrated that 1 is an excellent probe for Fe3+, CrO42‒ and Cr2O72‒ in water. The Ksv values of 1 for Fe3+, CrO42‒, and Cr2O72‒, which were as high as 1.06 × 104 M−1, 1.50 × 104 M−1, and 1.16 × 104 M−1, respectively, were comparable with those of other sensors. The quenching mechanism of the novel probe was subsequently explained.Graphic Abstract

Ru-90@bio-MOF-1: A ruthenium(II) metallodrug occluded in porous Zn-based MOF as a strategy to develop anticancer agents

One of the major challenges in the field of biomedicine is to use biocompatible carriers to achieve efficient drug delivery in the body. Most of the existing carriers have shown poor loading and rapid drug release. In this context, a subclass of coordination polymers, known as Metal-Organic Frameworks (MOFs), has attracted huge research interest: the unique physical properties of MOFs make them exceptional materials for drug delivery systems. Here, we have synthesized and characterized a non-toxic Zn-based MOF, designated bio-MOF-1, by using 4,4′-biphenyl-dicarboxylic acid and adenine as linkers. The microcrystalline porous material presented great loading capacity (0.340 ​g·g−1) for the antitumoral metallodrug Ru-90 [cis-[Ru(bpy)2(NO2)(solv)](PF6)]. The cellular viability results demonstrated that metallodrug occlusion facilitated its access and increased its availability in the cells. Ru-90 release from bio-MOF-1 depended on pH, so this material is a promising candidate for anticancer drug delivery. Moreover, application of kinetic equation models revealed that the mechanism of Ru-90 release from bio-MOF-1 fitted the Korsmeyer-Peppas model for the system at pH 5.0 and pH 7.4; the plots displayed high linearity and correlation coefficient values (R2) greater than 0.96. The n values were under 0.45 (Korsmeyer-Peppas model), which suggested the quasi Fickian model for the transport mechanism. In conclusion, the kinetic study results showed that bio-MOF-1 delivers the anticancer complex Ru-90 mostly through a diffusive mechanism.

Phase transformations in a complete monolayer of 4,4′-biphenyl-dicarboxylic acid on Ag(0 0 1)

Self-assembly is a bottom-up approach to prepare nanostructures with tailored properties. However, to utilize them as functional 2D layers, it is mandatory to understand their formation and its kinetics. Here, we describe the phase transformations in the full monolayer coverage of 4,4′-biphenyl-dicarboxylic acid (BDA) on the Ag(001) substrate. The phase transformations occur as a response to a thermally induced deprotonation of carboxyl groups. Contrary to the sub-monolayer coverage, the mass transport via on-surface diffusion in the full monolayer is hindered. We highlight two possible scenarios for the deprotonation of BDA in the full layer. For deprotonation of up to half of the carboxyl groups, the altered molecules can be incorporated within the existing α phase structure, forming a new binding motif. For structural changes that are required to respond to the further deprotonation, free substrate areas are necessary. The free surface is provided either by voids in the original layer or by removing excessive molecules, resulting in incomplete layers. This knowledge is essential in the fabrication of molecular layers that are part of hybrid organic–inorganic devices based on layered materials.

Water-Stable Zn(II) Coordination Polymers Regulated by Polysubstituted Benzenes and Their Photocatalytic Performance toward Methylene Blue Degradation Dominated by Ligand-Field Effects

Photodegradation of organic dyes over coordination polymer (CP) photocatalysts has become one of the effective strategies for the prevention and control of water pollution, in which the energy band structures manipulated by the ligand field of the catalytically active metal play extremely vital roles in enhancing the photocatalytic activity. To better rationalize the ligand-field function on the band structure, a series of six 2,4,6-tris(4-pyridyl)-1,3,5-triazine (tpt)-based Zn(II)-CPs have been hydrothermally prepared by transforming the types, numbers, and locations of the coordinative substitutes attached on benzene. All of these Zn(II)-CPs have been fully structurally and photophysically characterized and used as photocatalysts for methylene blue (MB) decontamination by UV light illumination. Single-crystal structural analyses reveal that isomeric 1,2,4 (H3L1)- and 1,3,5-benzenetricarboxylates (H3L2) have assembled the ternary system into the gridlike framework {[Zn(tpt)(HL1)]·H2O}n (1), ribbon-to-connector aligned sheet [Zn3(H2O)(tpt)2(L1)2]n (2), and hexagonal dimer based double layer [Zn3(H2O)2(tpt)(L2)2]n (3). 1,2,4,5-Tetrasubstituted phenyl and diphenyl coligands have assisted in honeycomb-shaped, pillared-layer, and cuboid-like frameworks via synergetic binding of carboxylate, sulfonate and hydroxyl moieties: {[Zn2(tpt)(H2L3)(L3)0.5]·0.5H2O}n (4, H4L3 = 2,5-dihydroxyltelephthalic acid), {[Zn2.5(tpt)(μ-OH)(L4)]·1.5H2O}n (5, H4L4 = 5-sulfobenzene-1,2,4-tricarboxylic acid), and {[Zn3(H2O)0.5(tpt)2(μ-OH)(L5)1.25]·5H2O}n (6, H4L5 = 3,3′-disulfonyl-4,4′-biphenyldicarboxylic acid). More significantly, the changeable donor surroundings around the Zn(II) ions have optimized the ligand-field geometries, giving rise to variable band gaps and band potentials. Resulting from the effective isolation and migration of the charge carriers and much stronger oxidizing ability of the valence band, the cuboid-shaped framework 6 has exhibited the best photodegradation activity toward the MB pollutant, up to 89% after 4 h UV illumination. These observations have systematically revealed the consequence of the ligand field on the CP photocatalysts in organic dye photodecomposition.

Water-stable Cd(ii)/Zn(ii) coordination polymers as recyclable luminescent sensors for detecting hippuric acid in simulated urine for indexing toluene exposure with high selectivity, sensitivity and fast response.

Three novel Cd(ii)/Zn(ii) coordination polymers (CPs), namely [Cd(L)(BPDC)0.5H2O]·0.5H2O (1), [Zn2(L)2(BPDC)]·2H2O (2) and [Cd2(L)(BTC)H2O]·3H2O (3) (L = 4-(tetrazol-5-yl)phenyl-4,2':6',4''-terpyridine, H2BPDC = 4,4'-biphenyldicarboxylic acid, and H3BTC = 1,3,5-benzenetricarboxylic acid), have been successfully synthesized and characterized. CP 1 and CP 2 display new two-dimensional double-layered honeycomb frameworks containing uncoordinated nitrogen atoms from pyridine and tetrazole rings, which can easily form hydrogen bonds with various analytes. CP 3 exhibits a 3D framework also with uncoordinated nitrogen atoms from pyridine and tetrazole rings. The fluorescence explorations indicate that CPs 1-3 exhibit strong blue luminescence and excellent chemical stability under a relatively wide range of pH conditions. It is worth noting that CPs 1-3 can quantitatively detect hippuric acid (HA), which is a metabolite of toluene in human urine, with high selectivity, sensitivity, fast response and relatively low detection limits. Moreover, the sensing mechanism of CPs 1-3 for HA can mainly be ascribed to fluorescence resonance energy transfer (FRET). CPs 1-3 could be ideal candidates as HA sensors in human urine samples for practical applications. Notably, to the best of our knowledge, we report for the first time Cd(ii)/Zn(ii)-based luminescent sensors for detecting HA in simulated urine.

Inclusion of viologen cations leads to switchable metal-organic frameworks.

The reactions of Zn(NO3)2·6H2O with the polycarboxylic acids 1,3-benzenedicarboxylic acid (H2mbdc), 1,4-benzenedicarboxylic acid (H2bdc), 1,3,5-benzenetricarboxylic acid (H3btc) and 4,4'-biphenyldicarboxylic acid (H2bpdc) in the presence of methyl viologen iodide ([MV]I2) in DMF gave anionic frameworks with methyl viologen species incorporated as counter-ions. When the reactions were carried out at 120 °C, the blue products [MV][Zn3(mbdc)4] (1-ht), [MV]0.44[H2MV]0.36[NMe2H2]0.4[Zn3(bdc)4]·0.6DMF (2-ht), [MV]0.5[Zn(btc)]·DMF (4-ht) and [MV][Zn4(bpdc)5]·8DMF·10H2O (5-ht) were formed, and these were shown to contain the radical cation [MV]˙+. In contrast, the same reactions carried out at 85 °C gave orange isostructural compounds containing the dication [MV]2+. Similar observations were made for reactions with ethyl viologen bromide. The compounds 1-ht, 2-ht and 4-ht contain similar framework topologies to analogues in which NMe2H2+ is the included cation. In contrast, 5-ht is based on a previously unreported interpenetrated network. Compound 2-ht contains the protonated species [H2MV]2+ in addition to [MV]˙+ and the crystal structure shows that the two rings in the former are staggered with respect to each other. This species is believed to form under the reaction conditions employed in the synthesis and the formation of [H2MV]2+ is suppressed by using an alternative approach in which methyl viologen is formed in situ from viologen diacetic acid. In the bdc-containing products, the radical cation is rapidly oxidised to the dication on exposure to air, as witnessed by the colour change from blue to orange. This change is reversed either by heating to 120 °C or exposure to UV radiation, both under nitrogen. This is in contrast to observations with the mbdc and btc analogues 1-ht and 4-ht, as in these compounds the blue colour persists for weeks. The difference can be related to the structures, with the channels present in 2-ht allowing oxygen to reach the radical cations.

Synthesis, structure and gas adsorption properties of coordination polymers based on mixed imidazole-containing ligands and carboxylate ligands

Herein, we report the synthesis of two novel coordination polymers using a combination of imidazole-containing ligands, namely 1,3,5-tris((1H-imidazol-1-yl)methyl)benzene (L1) and 3,3′,5,5′-tetra(1H-imidazol-1-yl)-1,1′-biphenyl (L2) and a carboxylate ligand derived from 4,4′-biphenyldicarboxylic acid (H2BPDC). The structures of the two coordination polymers [Ni(L1)(BPDC)]·2H2O (1·2H2O), which exhibits a 2-fold interpenetrated 3D → 3D architecture, and {[Co(CH3OH)2(L2)0.5(BPDC)] (2) possessing a 2D framework, have been determined. Moreover, the gas adsorption properties of 1 and 2 have been investigated.

Recyclable and reusable chiral α, α-L-diaryl prolinol heterogeneous catalyst grafting to UiO-67 for enantioselective hydration/aldol/oxa-Diels Alder domino reaction

α,α-L-Diaryl prolinol was first introduced into a highly stable porous MOF, UiO-67, via the immobilization of a chiral prolinol side chain into 4,4′-biphenyldicarboxylic acid through a five-step process, to construct a chiral heterogeneous catalyst. The catalyst exhibited high yield (up to 88%) and excellent stereoselectivities (up to >4:1 dr, > 80% ee) for the enantioselective hydration/aldol/oxa-Diels Alder domino reactions, as well as good reusability with recycle use for three times without significant loss of activity. To our knowledge, this is the first report of chiral MOFs as heterogeneous catalysts for asymmetric domino reactions.

Metal ions Directed Self‐assembly based on Mixed Ligands: From 2D hcb Net to 3D cds Framework

Two coordination polymers (CPs), namely, [Zn(BPDC)(3‐bpdb)0.5(H2O)2]n (1), and [Ni(BPDC)(3‐bpdb)(H2O)2]n (2) (where H2BPDC = 4,4'‐biphenyldicarboxylic acid, 3‐bpdb = 1,4‐bis(3‐pyridyl)‐2,3‐diaza‐1,3‐butadiene) have been solvothermally synthesized and characterized by single‐crystal X‐ray diffraction, IR, elemental analyses, PXRD, and SEM. CP 1 possesses a 2D 3‐connected hcb net, and weak hydrogen bonding and π···π stacking contacts further link the 2D networks to form 3D supramolecular structure. The structure of 2 presents a 4‐connected threefold interpenetrated cds framework. Through structural analysis, it is found that the coordination geometry of metal ions significantly affects the binding behaviors of the ligands and the resultant extended networks of the CPs. Besides, the Hirshfeld surface analyses detailed the surface characteristics of the two CPs. In addition, the thermal stabilities and photoluminescent properties were also investigated.

Perfluorooctane sulfonate removal by metal-organic frameworks (MOFs): Insights into the effect and mechanism of metal nodes and organic ligands

The metal–organic frameworks (MOFs) with different metal nodes and organic ligands have been prepared and used to remove perfluorooctane sulfonate (PFOS) from water. The results show that among three metal nodes of the MIL-53(Al), MIL-53(Fe) and MIL-101(Cr), MIl-53(Al) exhibit the best PFOS adsorption performance owing to the combined action of the highest unsaturated metal active sites and the smallest pore size. MIL-53(Al)-terephthalic acid (BDC), MIL-53(Al)-dimethyl 2,6-naphthalene dicarboxylate (NDC) and MIL-53(Al)-biphenyl-4,4′-dicarboxylic acid (BPDC) differs from the length of the organic ligand and MIL-53(Al)-BPDC achieves superior PFOS adsorption performance. We propose that longer organic ligand will contribute to larger 1D channel window and provide more PFOS entry. Adsorption kinetics shows that the experimental values can be well fitted to pseudo-second-order model, indicating that chemical adsorption demonstrate in the adsorption process. Besides, the existence of Fe3+ ions in MOFs/PFOS system could improve PFOS removal because of the bridging and interaction between Fe3+ ions and the PFOS molecule, which is confirmed by the density functional theory (DFT) calculation. These optimized MOFs are hopeful adsorbents to remove PFOS from water in a sustainability perspective.

Electrochemically Active In Situ Crystalline Lithium-Organic Thin Films by ALD/MLD.

Intercalated metal–organic framework (iMOF) type electrochemically active aromatic metal carboxylates are intriguing material candidates for various energy storage devices and microelectronics. In this work, we grow in situ crystalline thin films of such materials through atomic/molecular layer deposition (ALD/MLD); the remarkable benefit of this approach is the possibility to evaluate their electrochemical properties in a simple cell configuration without any additives. Five organic linkers are investigated in combination with lithium: terephthalic acid (TPA), 3,5-pyridinedicarboxylic acid (PDC), 2,6-naphthalenedicarboxylic acid (NDC), 4,4′-biphenyldicarboxylic acid (BPDC), and 4,4′-azobenzenedicarboxylic acid (AZO). In particular, the electrochemical activity of Li-PDC and the crystal structure of Li-AZO are addressed here for the first time. We believe that the in situ gas-phase thin-film deposition is a crucial requirement to benefit from the iMOF-type electrode materials in, e.g., microelectronics and wearable devices.