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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]

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.

Metal-organic frameworks (MOFs) as types of proton conductive materials have attracted much attention. Here, an acylamide-functionalized 3D MOF, [Ni 3 (TPBTC) 2 (stp) 2 (H 2 O) 4 ]·2DMA·32H 2 O, has been successfully constructed via combining Ni(NO 3 ) 2 , TPBTC (TPBTC = benzene-1,3,5-tricarboxylic acid tris-pyridin-4-ylamide) and 2-H 2 stp (2-H 2 stp = 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.

Octameric Aep1 was employed, for the first time to the best of our knowledge, as a nanopore to expand applications. After investigating the optimized conditions of Aep1 for single-channel recording, the sensing features were characterized. Cyclic and linear molecules of varying sizes and charges were employed to probe the radius and chemical environment of the pore, providing deep insights for expected future endeavors at predicting the structure of octameric Aep1. γ-CD showed unique suitability as an 8-subunit adapter in octameric Aep1, enabling the discrimination of β-nicotinamide mononucleotide.

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 (-SO 3 H) 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.

A complete core-shell and highly symmetric B 96 was designed. The core-shell B 96 of T h 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.