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The introduction of halogen atoms into the skeleton to regulate the intrinsic properties or improve task-specific performance of metal–organic frameworks (MOFs) has developed rapidly in recent years. Herein, a series of halogen-engineered MOFs were designed and prepared for electrochemical glucose sensing. Three isomorphic Ni-MOFs were constructed by using tetra-halogenated-phthalic acids as the organic ligand and incorporating 4,4′-bipyridine as an auxiliary ligand. Halogen atoms can enhance the stability of Ni-MOFs through their hydrophobicity and interlayer halogen bonds (X–X or X–π, X = F, Cl, Br). Combined experimental and theoretical results show that the hydrogen bond between halogen atoms and glucose improves the reaction thermodynamics, enabling the wide linear range of 0.01–5.0 mM, high sensitivity of 4709.9 μA mM−1 cm−2 and low detection limit of 0.043 μM. This work provides practical guidance for the rational design of halogenated MOFs and promotes their applications in electrochemical sensing. [ABSTRACT FROM AUTHOR]

A series of seaweed-like heterogeneous Co3(PO4)2/Ni3(PO4)2/MOF-74-x electrocatalysts were synthesized via a hydrothermal method. The optimal composite exhibits excellent catalytic performance toward methanol/ethanol oxidation reactions (MOR/EOR) with peak current densities reaching 27.5 and 32.6 mA cm−2, respectively. This work heralds the advent of more efficient heterogeneous electrocatalysts for DAFCs and other energy conversion systems. [ABSTRACT FROM AUTHOR]

Transition metal sulfides are low-cost oxygen evolution reaction (OER) electrocatalysts that can potentially substitute noble metal catalysts. However, the adsorption process of their OER is impeded by their intrinsic poor catalytic activity. Constructing heterojunction and vacancy defects in transition metal sulfides is an efficient method to promote the process of oxygen evolution. Herein, a facile approach based on in situ sulfurization of metal–organic gels (MOGs) and a short-time plasma treatment was developed to fabricate vacancy-modified polymetallic sulfides heterojunction. The synergistic effect of the multi-component heterojunction and sulfur vacancy contributed greatly to improving the electron migration efficiency and OER ability of the electrocatalyst. As a result, the optimum oxygen evolution activity was achieved with appropriate surface vacancy concentrations by regulating the plasma radio frequency powers. The plasma-treated catalyst under 400 W showed the best OER performance (lower overpotential of 235 mV in 1 M KOH solution with the Tafel slope of 31 mV dec−1) and good durability over 11 h of chronopotentiometry testing. This work sheds new light on constructing multimetal-based heterojunction electrocatalysts with rich vacancy defects for oxygen evolution reactions. [ABSTRACT FROM AUTHOR]

Recently, the detection of amino acids has attracted considerable attention in the field of nutrition analysis, health monitoring, and medical diagnosis due to their significance for organisms. In this work, two novel Cd(II)-based metal–organic frameworks (MOFs) with the formulas [Cd(bib)2(SiF6)]n (1) and {[Cd(bib)2(SiF6)]·DMF·3H2O}n (2, bib = 1-(4-imidazol-1-ylphenyl)imidazole) were synthesized and exhibited fluorescence sensing capacity for arginine. In spite of having the same framework composition, complexes 1 and 2 showed great differences in their structure originating in the variations between the coordination modes of SiF62− with Cd2+ and the extension direction of the Cd-bib coordination complexes. Structural analysis manifested that complex 1 featured a 3D coordination framework constructed from 2D Cd-bib coordination layers bridged by SiF62− anions, while complex 2 possessed 3-fold interpenetrated Cd-bib coordination networks connected by SiF62− anions. Furthermore, fluorescence sensing experiments exhibited that both complexes 1 and 2 could be used as fluorescence probes for arginine and the emission intensities of complexes 1 and 2 could be enhanced up to 10.3 and 12.0 times that of the initial emission intensities upon the addition of Arg, respectively. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) as types of proton conductive materials have attracted much attention. Here, an acylamide-functionalized 3D MOF, [Ni3(TPBTC)2(stp)2(H2O)4]·2DMA·32H2O, has been successfully constructed via combining Ni(NO3)2, TPBTC (TPBTC = benzene-1,3,5-tricarboxylic acid tris-pyridin-4-ylamide) and 2-H2stp (2-H2stp = 2-sulfoterephthalic acid monosodium salt) under solvothermal conditions. Single-crystal X-ray diffraction revealed that there are uncoordinated guest DMA molecules in the pores of the compound. On removal of guest DMA molecules, the proton conductivity of the compound increased to 2.25 × 10−3 S cm−1 at 80 °C and 98% RH which is about 110 times that of the original material. It is hoped that this work can provide essential insight for designing and obtaining improved crystalline-state proton conducting materials by considering the influences of guest molecules on proton conduction properties of porous materials. [ABSTRACT FROM AUTHOR]

Two new transition metal–organic frameworks (MOFs) formulated as [Zn3(Bip)3(H2sip)2(H2O)4]·5H2O (CUST-751) and [Cd3(Bip)2(H2sip)2(H2O)4]·2H2O (CUST-752) [CUST = Changchun University of Science and Technology, Bip = 3,5-bis(imidazole-1-yl)pyridine and H2sip = 5-sulfoisophthalic acid monosodium salt] have been constructed via a solvothermal reaction. Their crystal structures have been characterized by single crystal X-ray diffraction. CUST-751 exhibits a two-dimensional (2D) layered structure, while CUST-752 possesses a three-dimensional (3D) framework. Thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD) after treatment at different temperatures and different relative humidities (RHs) verified that they both have good thermal stabilities and water stabilities. Besides, their utility as fluorescence sensors has also been investigated. The results indicated that both CUST-751 and CUST-752 can be used as multiresponsive fluorescence sensors to detect Fe3+ and Cr2O72− with good sensitivity, high selectivity and recoverability, even in the presence of other interfering ions. More interestingly, CUST-751 is capable of selectively detecting 2,4,6-trinitrophenol (TNP). This work provides insights into the design and synthesis of transition metal based MOFs and explores their potential applications in the fluorescence sensing field. [ABSTRACT FROM AUTHOR]

Three new cucurbit[6]uril (CB[6])-based metal–organic rotaxane networks (MORNs) (named CUST-711, CUST-712, and CUST-713) functionalized by a sulfonic group (–SO3H) have been designed and synthesized via a hydrothermal method. All three compounds exhibited similar two-dimensional (2D) wave layer structures. Their stability under different temperature and relative humidity conditions has been investigated and all the compounds showed excellent stability. Furthermore, their proton conduction properties were also discussed in detail. Due to different structures and sulfonic group sites, the three compounds exhibited different proton conduction abilities of which CUST-712 exhibited an intrinsic relatively high proton conductivity (1.75 × 10−4 S cm−1 at 85 °C and 97% relative humidity). These results provide ideas for the design and synthesis of functional CB[6]-based metal–organic rotaxane frameworks (MORFs) as proton conducting materials. [ABSTRACT FROM AUTHOR]

A complete core–shell and highly symmetric B96 was designed. The core–shell B96 of Th symmetry is energetically favorable compared to the bilayer motif and the core–shell structure can be well maintained during first-principles molecular dynamics simulations at high temperatures (up to 1000 K). Moreover, it exhibits a superatomic electronic configuration and spherical aromaticity. Our theoretical work not only confirmed that the core–shell structural pattern is more energetically favorable for large-sized boron clusters, but also provided a strategy to design large boron clusters with a core–shell structure of high symmetry. [ABSTRACT FROM AUTHOR]

We developed a dual-responsive fluorescent probe MC-V-P for the simultaneous detection of ONOO− and viscosity by different imaging channels. MC-V-P has high sensitivity and selectivity, and shows good stability at different pH levels. Notably, the probe has two independent fluorescence signals toward ONOO− and viscosity changes at 580 nm and 740 nm, respectively. Cell imaging experiment results demonstrated that MC-V-P exhibits low cytotoxicity and could be used to monitor viscosity and ONOO− in living HepG2 cells simultaneously. [ABSTRACT FROM AUTHOR]

Polymer-based hydrogels used in the vitreous cavity could lead to an unsatisfactory gel-forming state, uncontrollable swelling, and potential cytotoxicity. Their application can significantly impair the filling effect and cause severe side effects in the surrounding tissues. To address the concerns, a poly(ethylene glycol)-engineered hydrogel capable of fast in situ gel formation (less than 1 min), with an ultralow swelling ratio and no cytotoxicity in the rabbits' eyes, was constructed as a vitreous substitute. The multi-arm polyethylene glycols (PEGs) modified with functional groups (thiol and maleimide) possess high reaction efficiency in the vitreous cavity and present excellent biomimetic characteristics of the natural vitreous humor in vitro. After injection with a double syringe via a 25-gauge needle in the eyes of rabbits for 6 months, the hydrogel functioned as an artificial vitreous body that could highly promote retinal detachment repair, with excellent biocompatibility and high transparency, and without bio-degradation or ocular complications. Collectively, the fast in situ forming hydrogel could achieve quick and good filling in the vitreous cavity without cytotoxicity, which makes it a promising long-term endotamponade substitute. [ABSTRACT FROM AUTHOR]

Co-catalysts have been widely studied to improve photocatalytic water oxidation efficiency, and the precise control of their oxidation states and minimizing particle sizes can optimize the practical performance. In this work, ultrafine cobalt oxide (CoOx) co-catalysts with specific Co valence states have been successfully synthesized, which are anchored on a tantalum oxynitride (TaON) host photocatalyst via a photochemical metal–organic deposition method. Photoelectrochemical and photoluminescence analyses prove that the Co2+ dominant CoOx co-catalyst is favorable for charge separation and transportation because of its excellent hole-capturing properties, consequently enhancing the photocatalytic water oxidation performance. The resultant TaON with the Co2+ dominant CoOx co-catalyst exhibits an outstanding O2 production rate up to 6.10 ± 0.17 mmol h−1 g−1 and possesses an excellent apparent quantum efficiency of 21.2% at 420 nm, which are among the best values of water-oxidation photocatalysts. [ABSTRACT FROM AUTHOR]

Stimulated by the early theoretical prediction of B80 fullerene and the experimental finding of the B40 cage, the structures of medium-sized boron clusters have attracted intensive research interest during the last decade, but a complete picture of their size-dependent structural evolution remains a puzzle. Using a genetic algorithm combined with density-functional theory calculations, we have performed a systematic global search for the low-lying structures of neutral Bn clusters with n = 31–50. Diverse structural patterns, including tubular, quasi-planar, cage, core–shell, and bilayer, are demonstrated for the ground-state Bn clusters; for certain cluster sizes, unprecedented geometries are predicted for the first time. Their stabilities at finite temperatures are evaluated, and the competition mechanism between various patterns is elucidated. Chemical bonding analysis reveals that the availability of localized σ bonds and delocalized π bonds in the Bn clusters play a key role in their structural stability. Our results provide important insights into the bonding pattern and growth behavior of medium-sized boron clusters, which lay the foundation for experimental design and synthesis of boron nanostructures. [ABSTRACT FROM AUTHOR]

The selective adsorption/separation of C2 hydrocarbons has been realized in a "flexible-robust" MOF, Zn2(Atz)2Ox. Owing to the distinctive guest-dependent multistep adsorption behaviors and suitable guest–framework interactions, this MOF shows outstanding separation performance for C2H2/C2H4 mixtures in a wide range of temperature confirmed by a column breakthrough experiment. [ABSTRACT FROM AUTHOR]

The concomitant formation of metallic Bi nanoparticles and oxygen vacancies was successfully achieved within Bi/BiOBr/RGO composites by facile and green UV-light exposure. Detailed characterization showed that Bi nanoparticles with an average size of ca. 25 nm and oxygen-vacancies were fabricated simultaneously in this preparative process. The photocatalytic activity in aqueous methylene blue (MB) solution showed that the Bi/BiOBr/RGO composites revealed superior performance over the counterparts and their photocatalytic activities were highly dependent on the light irradiation time of the preparation process. Among all the as-prepared samples, the sample prepared under UV-light irradiation of 40 min exhibited the highest photocatalytic activity and the removal rate of MB was 99.9% under visible-light within 240 min. The mechanism study proved that the improvement in the photocatalytic efficiency of Bi/BiOBr/RGO composites could be ascribed to the synergy of the surface plasmon resonance (SPR) effect of Bi, conductive RGO and oxygen vacancies, all of which enhanced the visible light harvesting and effective separation of electron–hole pairs. The present work not only provided a facile green and low-cost method to simultaneously incorporate Bi and oxygen vacancy into composites but also confirmed that UV-light irradiation was one effective method to tune the photocatalytic performance of the composites. [ABSTRACT FROM AUTHOR]

Two new cucurbit[6]uril (CB[6])-based metal–organic rotaxane networks (MORNs) were successfully obtained by tuning the coordination sphere of metal copper clusters. Compounds 1 and 2 exhibited relatively high proton conductivity at 85 °C and 97% relative humidity (RH), providing great promise for fuel cell electrolyte materials. [ABSTRACT FROM AUTHOR]

A combined experimental and theoretical study is presented of several ligand addition reactions of the triplet fragment 3CpMn(CO)2 formed upon photolysis of CpMn(CO)3. Experimental data are provided for reactions in n-heptane and perfluoromethylcyclohexane (PFMCH), as well as in PFMCH doped with C2H6, Xe and CO2. In PFMCH we find that the conversion of 3CpMn(CO)2 to 1CpMn(CO)2(PFMCH) is much slower (τ = 18 (±3) ns) than the corresponding reactions in conventional alkanes (τ = 111 (±10) ps). We measure the effect of the coordination ability by doping PFMCH with alkane, Xe and CO2; these doped ligands form the corresponding singlet adducts with significantly variable formation rates. The reactivity as measured by the addition timescale follows the order 1CpMn(CO)2(C5H10) (τ = 270 (±10) ps) > 1CpMn(CO)2Xe (τ = 3.9 (±0.4) ns) ∼ 1CpMn(CO)2(CO2) (τ = 4.7 (±0.5) ns) > 1CpMn(CO)2(C7F14) (τ = 18 (±3) ns). Electronic structure theory calculations of the singlet and triplet potential energy surfaces and of their intersections, together with non-adiabatic statistical rate theory, reproduce the observed rates semi-quantitatively. It is shown that triplet adducts of the ligand and 3CpMn(CO)2 play a role in the kinetics, and account for the variable timescales observed experimentally. [ABSTRACT FROM AUTHOR]

By integrating open metal sites, Lewis basic sites, and tortuous diffusion paths, a new metal–organic framework has been designed and synthesized, which exhibits high adsorption capacity and excellent selectivity for separating a C3H4/C3H6 mixture. Meanwhile, the molecular packing state, dynamic diffusion coefficient of gases within the framework, and binding interaction are studied by molecular simulations. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries have received increasing attention due to their high energy density. However, it is still challenging to inhibit the diffusion of polysulfides and achieve high sulfur utilization. Herein, we designed and prepared a free-standing and binder-free electrode for high-performance Li–S batteries by in situ growth of three-dimensional ordered macroporous MoO2 on carbonized nonwoven cloth (3DOM MoO2/CC). After the uptake of Li2S6, the obtained MoO2/CC–Li2S6 electrode with a high sulfur loading of 3.26 mg cm−2 delivers a large discharge capacity of 1267 mA h g−1 at 0.1C. A high discharge capacity of 621 mA h g−1 is still retained after 500 cycles at 2C. The excellent electrochemical performance of this MoO2/CC–Li2S6 electrode is attributed to the unique nanostructure and strong chemical interaction between MoO2 and polysulfides. 3DOM MoO2 not only guarantees the high loading of sulfur but also suppresses the diffusion of polysulfides. The carbonized nonwoven cloth (CC) functions as the basic support for 3DOM MoO2, enhancing the electronic conductivity and mechanical properties of the free-standing electrodes. This work provides a feasible strategy for the construction of high-performance free-standing binder-free Li–S electrodes. [ABSTRACT FROM AUTHOR]

Discrimination between cysteine and homocysteine at the single-molecule level is achieved within a K238Q mutant aerolysin nanopore, which provides a confined space for high spatial resolution to identify the amino acid difference with a 5′-benzaldehyde poly(dA)4 probe. Our strategy allows potential detection and characterization of various amino acids and their modifications, and provides a crucial step towards developing nanopore protein sequencing devices. [ABSTRACT FROM AUTHOR]

Three new high-dimensional cucurbit[6]-based metal–organic rotaxane frameworks [Co2(PR43)(BDC)2Cl2]·4H2O (1), [Co2(PR43)(BTC)2]·6H2O (2) and [Co2(PR43)(BPT)2]·20H2O (3) were obtained via the hydrothermal synthesis method. Compound 1 comprised a two-dimensional layered structure, while compounds 2 and 3 exhibited three-dimensional pillared structures. All the compounds showed good thermal stabilities. Furthermore, the magnetic properties of compounds 1–3 were also investigated in detail. [ABSTRACT FROM AUTHOR]

The formation of metal–organic frameworks (MOFs) under given reaction conditions depends on various factors including reaction duration, temperature, used solvent, system pH, and others. Among them, the reaction duration is relatively less investigated. In this work, based on a Cu(ii)-MOF system, the reaction duration was found to play an important role in directing the formation of two different products, (NH2(CH3)2)[Cu12(DDPN)6(H2O)10Cl] (BUT-301) on shorter reaction time and (NH2(CH3)2)2[Cu(DDPN)] (BUT-302) on longer reaction time, when CuCl2 reacted with 3,5-di(3,5-dicarboxylphenyl)nitrobenzene (H4DDPN) in a DMA/MeOH mixed solvent at 120 °C. With increasing the reaction duration, BUT-301 can transform into BUT-302. Both MOFs have three-dimensional (3D) framework structures. BUT-301 is constructed from paddle-wheel Cu2(COO)4 units and DDPN4– ligands as four-connected linkers, while BUT-302 is assembled from mononuclear Cu(ii) centers connecting the ligands as also four-connected linkers but in a monodentate coordination fashion. N2 adsorption confirmed that both MOFs are porous materials with the Brunauer–Emmett–Teller (BET) surface areas of 1953 and 561 m2 g−1, respectively. Interestingly, both BUT-301 and -302 show selective adsorption properties of C3H4 over C3H6. The C3H4/C3H6 adsorption selectivities were calculated to be 1.9 and 4.4 at 0.1 bar and 298 K by the ideal adsorbed solution theory (IAST) for a 1 : 99 C3H4/C3H6 mixture, respectively. [ABSTRACT FROM AUTHOR]

Luminescent hybrid materials based on nanodiamonds (NDs) and rare earth ions have been successfully synthesized by covalently modifying NDs with pyromellitic acid (PMA) which is capable of coordinating to Eu3+ and Tb3+ ions. With NDs acting as a host matrix, the PMA and rare earth ions serve as an organic sensitizer and activator, respectively, yielding a highly bright hybrid composite. Interestingly, for the co-doped hybrid composites ND-PMA-Eu/Tb, the intensity ratio of the two emissions, 5D4→7F5 transition (Tb3+) to 5D0→7F2 transition (Eu3+), is linearly related to temperature in the range from 77 K to 277 K. Therefore, the hybrid could be developed as a self-calibrated ratiometric luminescent thermometer due to its temperature-dependent luminescence performance. [ABSTRACT FROM AUTHOR]

Covering: 2000 to 2018 (October) Trillions of microbes, collectively termed as gut microbiota, reside in the gastrointestinal tract and are involved in the physiology of their hosts. In humans, disease incidence and medical therapy are found to be associated with gut microbiota composition. Since ethnomedicines are largely plant-derived and orally ingested, this review summarizes the interactions of gut microbiota with ethnomedicine constituents (overwhelmingly, natural phytochemicals) to highlight the knowledge accumulation in (1) the modulation of the gut microbiota profile by ingested natural compounds, and (2) the gut microbial conversion of natural products into the ‘daughter molecules’ with potent bioactivities. By understanding such complex interactions of gut microbiota with ethnomedicines and/or the phytochemicals thereof, a fascinating frontier of natural-product chemistry may be substantially activated to conceptualize future therapeutic strategies. [ABSTRACT FROM AUTHOR]

A top-down method was developed to synthesize hierarchical composites consisting of NiCo2O4 nanocubes and graphene nanosheets through the electrostatic interaction of negatively charged graphene oxide nanosheets and positively charged NiCo2O4 spheres. Employed as anode materials for lithium-ion batteries, the hierarchical composites exhibit remarkably high electrochemical performance, including large reversible capacity, superior rate capability, and excellent cycling performance. Large reversible capacities of 1024 and 648 mA h g−1 are maintained at a current density of 500 and 3000 mA g−1, respectively, for over 200 cycles. The excellent electrochemical performance of the composite is attributed to the synergistic effect of the hierarchical structure, the well dispersed NiCo2O4 nanocubes and the uniform graphene coating. This work provides an effective and promising strategy for the rational structural design of the metal oxide electrode material. [ABSTRACT FROM AUTHOR]

In the design and construction of metal–organic frameworks (MOFs), the utilization of slim ligands is usually more inclined to form interpenetrated structures compared with bulky ones. The structural interpenetration can improve the framework stability and in some cases, enhance gas adsorption capacity and selectivity due to confined pores. In order to explore the structural control of MOFs and construct new MOFs with good selective gas adsorption ability, herein, a slim ethynyl-based 4-connected carboxylate acid ligand, 4,4′,4′′,4′′′-(benzene-1,2,4,5-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid (H4BTEB), was used to design and construct MOFs, hopefully having interpenetrated structures. Combining with 4-connected paddle-wheel Cu2(COO)4 and 8-connected Zr6O4(OH)8(COO)8 clusters, BTEB4− ligand led to two new MOFs, [Cu2(BTEB)(H2O)2] (BUT-43) and [Zr6O4(OH)8(H2O)4(BTEB)2] (BUT-44). As expected, the two MOFs have two-fold interpenetrated framework structures with partitioned channels. BUT-43 contains a rare three-dimensional (3D) 4-connected single network with lvt topology, which then interpenetrates. In BUT-44, each Zr6-based cluster is coordinated with eight BTEB4− ligands to give a single 3D 4,8-connected scu network, which then doubly interpenetrates to give the first example of interpenetrated 4,8-connected Zr(iv)-MOF. Studies on their stability and gas adsorption properties demonstrate that BUT-44 shows higher stability in NaOH solution of pH 10 and 1 M HCl aqueous solution. More interestingly, both MOFs represent good gas adsorption selectivities for C2H2 over CO2 and CH4, suggesting potential application in gas separation. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries as a promising next-generation energy storage device have received increasing attention recently. However, it is still challenging to achieve high sulfur loading and high areal capacity in the cathodes. Herein, we design a composite of carbon-wrapped Fe/Fe3C nanoparticles grown in a carbonized melamine sponge (Fe/Fe3C@N-CNT) as a free-standing conductive framework and host scaffold for sulfur loading. High sulfur content up to 86.9 wt% and overall mass loading as high as ∼14.44 mg cm−2 are achieved in the resultant Fe/Fe3C@N-CNT/S composite. A high discharge capacity of 1359 mA h g−1 is delivered for this Fe/Fe3C@N-CNT/S composite at 0.1C, and 561 mA h g−1 is retained after 150 cycles. The high electrochemical performance of this Fe/Fe3C@N-CNT/S composite is attributed to the synergistic effect of Fe/Fe3C nanoparticles, carbon coating, and N-doped carbon nanotubes in the Fe/Fe3C@N-CNT cathode. [ABSTRACT FROM AUTHOR]

The first CB[6]-based 3D porous metal–organic rotaxane framework is constructed by the reaction of CuCl2, terephthalic (H2BDC) and CB[6]-based [2]pseudorotaxanes ([PR44]2+·2[PF6]−) under solvothermal conditions. The structure of MORF-1 is a pillared-layer structure with 5-connected sqp topology, in which the effective free volume is 45.4% of the crystal volume. The guest molecules exchange in a single-crystal-to-single-crystal fashion, which was investigated using NMR spectroscopy and X-ray crystallography. [ABSTRACT FROM AUTHOR]

By utilizing symmetrical pentacarboxylate ligands, 3,5-di(2′,5′-dicarboxylphenyl)benzoic acid (H5L1) and 3,5-di(2′,4′-dicarboxylphenyl)benzoic acid (H5L2), two novel porous Zn-MOFs, [Zn5(μ3-H2O)2(L1)2]·3DMA·4H2O (CTGU-3) and [Zn3(μ3-OH)L2(H2O)3]·H2O (CTGU-4) have been synthesized under solvothermal conditions. CTGU-3 and CTGU-4 exhibit 3D microporous frameworks with flu and dia topologies and possess unique secondary building units [Zn5(μ3-H2O)2(RCO2)6] and [Zn3(μ3-OH)(RCO2)3], respectively. Such porous systems create a unique space or surface to accommodate Ag nanoparticles (Ag NPs), which could efficiently prevent Ag NPs from aggregation and leaching. In this work, two new Ag@Zn-MOF composites, denoted as Ag@CTGU, have been successfully fabricated through solution infiltration, for the reduction of nitrophenol. Compared with CTGU-4, CTGU-3 shows enhanced catalytic efficiency toward the reaction when it is used as a catalyst support of Ag NPs. Moreover, gas sorption and luminescence properties of two compounds were also investigated. [ABSTRACT FROM AUTHOR]

A super-stable multifunctional terbium(iii)–organic framework, namely {[Tb(TATAB) (H2O)2]·NMP·H2O}n (Tb-MOF, H3TATAB = 4,4′,4′′-s-triazine-1,3,5-triyltri-m-aminobenzoic acid, NMP = N-methyl-2-pyrrolidone) was synthesized. Tb-MOF exhibits a 2D sql structure with binuclear [Tb2(COO)4(H2O)4]2+ units as 4-connected nodes, and free water and NMP molecules are inserted between 2D layers through hydrogen-bonding interactions, forming a sandwich-type architecture. Observably, such a framework remains intact in a remarkable variety of environments such as common solvents and aqueous solutions with metal cations and inorganic anions, as well as with a pH ranging from 1 to 13. In particular, Tb-MOF can not only detect small organic molecules, metal cations and inorganic anions with high sensitivity and high selectivity, but also can accurately detect explosive 2-nitrophenol, 3-nitrophenol, 4-nitrophenol and 2,4,6-trinitrophenol in water. Its luminescence quenching response to Fe3+ and Cr2O72− ions can be explained in terms of the competitive absorption mechanism. In addition, the luminescence intensity of Tb-MOF is strongly correlated with the pH value in a pH range from 1 to 13. Thus, this material can be potentially used as a multi-responsive luminescent sensor. [ABSTRACT FROM AUTHOR]

A novel magnetic carbon-based nickel and sodium silicate catalyst (Na2SiO3@Ni/C) was prepared by the precipitation of Ni(OH)2 on bamboo powders, pyrolysis and the loading of Na2SiO3, and was used in the co-production of biodiesel and hydrogen. The catalyst had strong magnetism (magnetic saturation, Ms of 15.7 Am2 kg−1) from the Ni and basicity (3.18 mmol g−1) from the Na2SiO3 for magnetic separation and biodiesel production. In the presence of Na2SiO3@Ni/C, a biodiesel yield of 98.1% was achieved from soybean oil under the best conditions (9/1 methanol/oil molar ratio, 7 wt% catalyst, 65 °C for 100 min), optimized by single-factor experiments. The catalyst was cycled 4 times with biodiesel yields ＞93%, but the yield dropped to 80.9% with a 85.3% catalyst recovery rate in the fifth cycle. The deactivated catalyst, after 5 cycles, catalyzed the hydrothermal gasification of a biodiesel by-product (crude glycerol) at 350 °C for 5 min with a gasification rate of 80.1% and 82.7% H2 purity. The role of Ni is to catalyze the H2 production while the role of Na2SiO3 is to absorb CO2 to achieve high H2 concentrations. After gasification, the structure of the Ni/C changed slightly and can still be cycled to load Na2SiO3 for biodiesel production and subsequent gasification. [ABSTRACT FROM AUTHOR]

Five new metal–organic rotaxane frameworks (MORFs) have been hydrothermally synthesized by systematically combining cucurbit[6]uril-based pseudorotaxanes, rigid carboxylate ligands and d10 metal ions. Compound 1 presents a three-periodic pillared structure; 2 and 3 are two-periodic layers with hcb topologies; 4 presents a 3D structure with snw topology and 5 is a three-periodic network, featuring from interpenetrating to non-interpenetrating 3D MORFs. The cucurbit [6]uril-based MORFs obtained in this work illustrate the importance of non-covalent interactions around CB[6]s in the assembly of resultant super architectures. Furthermore, their TGA analysis, solid photoluminescence properties and sensitization to lanthanide ions are investigated. [ABSTRACT FROM AUTHOR]

Three polyoxovanadate-based metal–organic polyhedra (denoted as VMOP-1, -2, and -3), adopting isostructural discrete octahedral cage geometries, were successfully synthesized under solvothermal conditions. These structures are all built up from the same pentavanadate {V5O9Cl} cluster connected by linear bidentate ligands (H2L1 = H2BDC, H2L2 = H2BDC-NH2, H2L3 = H2BDC-Br), respectively. [ABSTRACT FROM AUTHOR]

Two unprecedented homochiral enantiomers based on two different kinds of rigid ligands, namely [Cd(NDC)L]2·H2O (1R and 1L), have been synthesized under hydrothermal conditions through spontaneous resolution. Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR, and thermogravimetric (TG) analysis. The resulting framework 1, constructed by four kinds of homo-handed helical chains represents the first 3D self-penetrating framework formed by decoration of single (10,3)-a net with helical chains. The single (10,3)-a net in 1 formed by three kinds of different homo-handed helical chains is different from the standard one, which should be ascribed to the usage of V-shaped ligand L. A unique self-penetration motif can be discovered in 1 where one helical chain alternately passes through 10-membered shortest circuits linked to each other and in contrary, the corresponding circuits are bound to the helical chain. Interestingly, 1 exhibits fluorescent emission in both the solid and solution phase. The uncoordinated nitrogen atom and amino group from the triazole core on the crystal surface make it suitable to detect picric acid in water. The luminescence intensity of 1 in water can be efficiently quenched by the addition of picric acid (PA). The sensitive detection of PA can be continuously performed for at least five cycles without diminishing the fluorescence intensity and destroying the framework structure of 1. The possible quenching mechanisms for PA are also investigated. [ABSTRACT FROM AUTHOR]

Six new Co(ii)-based mixed-ligand coordination polymers, namely, [Co2(H3bppc)2(2,2′-bpy)4]·H2O (1), [Co2(Hbppc)(2,2′-bpy)2(H2O)]·H2O (2), [Co(H2bppc)(H-bpp)]·2H2O (3), [Co3(μ3-OH)(bppc)(dps)(CH3CH2OH)]·4H2O (4), [Co2(bppc)(bib)(H2O)4]·(H2-bib)0.5·(H2O)3 (5), and [Co2(Hbppc)(bix)2]·2H2O (6), (H5bppc = biphenyl-2,4,6,3′,5′-pentacarboxylic acid, 2,2′-bpy = 2,2′-bipyridine, bpp = 1,3-bis(4-pyridyl)propane, dps = 4,4′-sulfanediyldipyridine, bib = 1,4-bis(imidazol-1-yl)benzene, bix = 1,4-bis(imidazol-1-ylmethyl)benzene), have been obtained under solvothermal conditions. 1 exhibits a 3D supramolecular framework based on a [Co2(H3bppc)2(2,2′-bpy)4] unit. 2 has a (3,4)-connected dmc net with a (4·82)(4·85) topology containing alternate binuclear metal clusters and single metal centres. 3 shows a 3D supramolecular architecture constructed from ladder-like arrays decorated with H-bpp. 4 exhibits a binodal (5,7)-connected 3D network based on trinuclear [Co3(μ3-OH)]5+ units with an unusual (3·46·52·6)(32·46·57·65·7) topology. 5 features a (4,6)-connected 3D fsc open framework with binuclear [Co2(H2O)(COO)]3+ units as nodes, and H2-bib and water molecules located in the voids of its framework by hydrogen bonds. 6 possesses a 3D net containing unusual 2D polyrotaxane sheets. Topological analysis reveals that 6 has a (3,4,4)-connected 3D network with a (4·6·74)(4·6·7)(6·72·102·11) topology. The structural difference of 1 and 2 is due to the different pH values of the reaction system. Though complexes 2–6 were synthesised under similar reaction conditions, the carboxylic groups of H5bppc were partially deprotonated in 2, 3 and 6 and fully deprotonated in 4 and 5. Complexes 2–6 display diverse structures depending on different N-donor ligands and the coordination modes of the multicarboxylate ligand. Variable-temperature magnetic susceptibility measurements reveal that complexes 1–6 show antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]