Regulating electron transfer and orbital interaction within metalloporphyrin-MOFs for highly sensitive NO2 sensing.

The understanding of electron transfer pathways and orbital interactions between analytes and adsorption sites in gas-sensitive studies, especially at the atomic level, is currently limited. Herein, we have designed eight isoreticular catechol-metalloporphyrin scaffolds, FeTCP-M and InTCP-M (TCP = 5,10,15,20-tetrakis-catechol-porphyrin, M = Fe, Co, Ni and Zn) with adjustable charge transfer schemes in the coordination microenvironment and precise tuning of orbital interactions between analytes and adsorption sites, which can be used as models for exploring the influence of these factors on gas sensing. Our experimental findings indicate that the sensitivity and selectivity can be modulated using the type of metals in the metal-catechol chains (which regulate the electron transfer routes) and the metalloporphyrin rings (which fine-tune the orbital interactions between analytes and adsorption sites). Among the isostructures, InTCP-Co demonstrates the highest response and selectivity to NO2 under visible light irradiation, which could be attributed to the more favorable transfer pathway of charge carriers in the coordination microenvironment under visible light illumination, as well as the better electron spin state compatibility, higher orbital overlap and orbital symmetry matching between the N-2s2pz hybrid orbital of NO2 and the Co-3dz2 orbital of InTCP-Co.

Superhydrophobic Pseudosupertetrahedral Sulfido Metalate Clusters for Constructing Liquid Marbles.

One pseudopentasupertetrahedral chalcogenidometalate cluster, [(BuSn)3SnCd4S13(OH)]·6(H+DMP) (PPS-1; H+DMP = protonated 3,5-dimethylpiperidine), has been isolated by use of an organotin precursor. They are arranged to generate two types of tetrahedrally patterned cages, which further interconnect to form a diamond network. Owing to the covalent attachment of abundant alkyl groups, PPS-1 exhibits excellent hydrophobicity and could be used as an assembly substance for building liquid marbles.

Thiophenol-spaced 2D coordination polymers with extraordinary alkali resistance and efficient photothermal conversion.

Coordination polymers (CPs) based on metal-sulfur bonds are rare; we herein realize a series of thiol-functionalized linker-based CPs (thiol-CPs), MTBT (M = Fe, Co and Zn; TBT = dehydrated 4,4'-thiobisbenzenethiol), which feature an anionic two-dimensional (2D) network, [M(TBT)2]n2n-, with the tetrahedral coordination unit {MS4} serving as a node. These compounds exhibit excellent hydrolytic stability, especially in alkaline solution (20M NaOH for five days), which is the highest value reported for CPs so far. In addition, among them, CoTBT displays favorable photo-thermal conversion effectiveness under an energy power of 0.5 W cm-2 808 nm laser irradiation for 15 s, with the temperature rising rapidly from room temperature to 135.2 °C.

Energy Band Alignment and Redox-Active Sites in Metalloporphyrin-Spaced Metal-Catechol Frameworks for Enhanced CO2 Photoreduction.

Two new chemically stable metalloporphyrin-bridged metal-catechol frameworks, InTCP-Co and FeTCP-Co, were constructed to achieve artificial photosynthesis without additional sacrificial agents and photosensitizers. The CO2 photoreduction rate over FeTCP-Co considerably exceeds that obtained over InTCP-Co, and the incorporation of uncoordinated hydroxyl groups, associated with catechol, into the network further promotes the photocatalytic activity. The iron-oxo coordination chain assists energy band alignment and provides a redox-active site, and the uncoordinated hydroxyl group contributes to the visible-light absorptance, charge-carrier transfer, and CO2 -scaffold affinity. With a formic acid selectivity of 97.8 %, FeTCP-OH-Co affords CO2 photoconversion with a reaction rate 4.3 and 15.7 times higher than those of FeTCP- Co and InTCP-Co, respectively. These findings are also consistent with the spectroscopic study and DFT calculation.

Understanding the Efficiency and Selectivity of Two-Electron Production of Metalloporphyrin-Embedded Zirconium-Pyrogallol Scaffolds in Electrochemical CO2 Reduction.

Because of the high efficiency and mild reaction conditions, electrocatalytic CO2 reduction (ECR) has attracted significant attention in recent years. However, the specific mechanism of the formation of the two-electron production (CO or HCOOH) in this reaction is still unclear. Herein, with density functional theory calculation and experimental manipulation, the specific mechanism of the selective two-electron reduction of CO2 has been systematically investigated, employing the polyphenolate-substituted metalloporphyrinic frameworks, ZrPP-1-M (M = Fe, Co, Ni, Cu, and Zn), as model catalysts. Experimental observations and theoretical calculations discovered that ZrPP-1-Co is a more favorable catalyst for ECR among them. Compared with the formation of HCOOH, electroreduction of CO2 into CO has more beneficial thermodynamic and kinetic routes with ZrPP-1-Co as a catalyst. After introducing the r-GO for improving the conductivity, the Faradaic efficiency for CO formation is 82.4% at -0.6 v (vs RHE).

Photochemical In Situ Exfoliation of Metal-Organic Frameworks for Enhanced Visible-Light-Driven CO2 Reduction.

Two novel two-dimensional metal-organic frameworks (2D MOFs), 2D-M2 TCPE (M=Co or Ni, TCPE=1,1,2,2-tetra(4-carboxylphenyl)ethylene), which are composed of staggered (4,4)-grid layers based on paddlewheel-shaped dimers, serve as heterogeneous photocatalysts for efficient reduction of CO2 to CO. During the visible-light-driven catalysis, these structures undergo in situ exfoliation to form nanosheets, which exhibit excellent stability and improved catalytic activity. The exfoliated 2D-M2 TCPE nanosheets display a high CO evolution rate of 4174 µmol g-1 h-1 and high selectivity of 97.3 % for M=Co and Ni, and thus are superior to most reported MOFs. The performance differences and photocatalytic mechanisms have been studied with theoretical calculations and photoelectric experiments. This study provides new insight for the controllable synthesis of effective crystalline photocatalysts based on structural and morphological coregulation.

A wide pH-range stable crystalline framework based on the largest tin-oxysulfide cluster [Sn20O10S34].

We report, herein, a diamond-like oxysulfide framework, 3D-T4-SnOS, based on the largest supertetrahedral cluster of Sn4+ ions, i.e. [Sn20O10S34]. The framework remains intact in aqueous solution over a pH range between 1 and 14, and has a narrower optical bandgap, red-shifted fluorescence emission, and an enhanced photoelectric response compared to that of the smaller version, 2D-T3-SnOS, which has a building unit of supertetrahedral [Sn10O4S20].

Robust Porphyrin-Spaced Zirconium Pyrogallate Frameworks with High Proton Conduction.

An isoreticular family of zirconium polyphenolate networks (ZrPP- n, n = 1 and 2), bridged by porphyrinic macrocycles in an eclipsed arrangement, have excellent stability toward water, especially strong basic media of saturated NaOH aqueous solution. Endowed with spatial alignment of protic sites, viz., partially protonated phenols of acidity enhanced by coordination to Zr4+, along with guest dimethylamine cations, the newly synthesized ZrPP- n reveal exceptional conductivity (8.0 × 10-3 and 4.2 × 10-3 S cm-1, for n = 1 and 2, respectively, pelleted sample, under 98% relative humidity at 25 °C).

Dual-cubic-cage based lanthanide sulfate-carboxylpyrazolate frameworks with high hydrolytic stability and remarkable proton conduction.

We report herein a series of lanthanide sulfate-carboxylpyrazolate frameworks based on double cuboid cavities that are highly hot-water stable, and have room-temperature proton conductivity of over 10-3 S cm-1 at 97% relative humidity without any appreciable loss of performance for at least three recycling times, ranking among the best lanthanide-based coordination frameworks.

Early predictors of hyperlipidemic acute pancreatitis.

The present study aimed to investigate early risk factors for hyperlipidemic acute pancreatitis (HLAP) in order to open up novel routes for its prevention and treatment. Demographics, laboratory data obtained within 48 h, enhanced computed tomography (CT) imaging data and the modified CT severity index (MCTSI) for 111 patients with HLAP who were assessed at Ordos Central Hospital (Ordos, China) between January 2015 and October 2017 were retrospectively analyzed. Of these, 17 patients progressed to infectious pancreatic necrosis (IPN) and 14 patients progressed to organ failure (OF), the occurrence of which were the study outcomes. The patients were divided into pairs groups: IPN and non-IPN, as well as OF and non-OF, and differences between the groups were determined regarding various clinicopathological parameters. Furthermore, univariate and multivariate regression analyses were performed to identify parameters associated with the risk of progression to IPN or OP. On univariate analysis, the following parameters were deemed as being significantly associated with the risk of IPN: Serum calcium ions, C-reactive protein (CRP), extent of necrosis, procalcitonin (PTC) and the MCTSI. Furthermore, calcium ions, red cell distribution width (RDW), extent of necrosis and the MCTSI were significantly associated with the risk of OF on univariate analysis. Multivariate logistic regression analysis for these parameters then indicated that CRP (P=0.014), RDW (P=0.025) and the extent of necrosis (P=0.022) were significant and independent predictors of progression; thus, these are early risk factors for patients with HLAP. Receiver operating characteristic curves were generated to evaluate the predictive value of these factors, and the area under the curve for the three parameters was 0.863 [95% confidence interval (CI), 0.646-0.886], 0.727 (95% CI, 0.651-0.803) and 0.833 (95% CI, 0.739-0.936), respectively. Therefore, CRP, RDW and the extent of necrosis are early predictive indexes for the risk of progression in HLAP.

Acid and Base Resistant Zirconium Polyphenolate-Metalloporphyrin Scaffolds for Efficient CO2 Photoreduction.

A series of zirconium polyphenolate-decorated-(metallo)porphyrin metal-organic frameworks (MOFs), ZrPP-n (n = 1, 2), featuring infinite ZrIV -oxo chains linked via polyphenolate groups on four peripheries of eclipse-arranged porphyrin macrocycles, are successfully constructed through a top-down process from simulation to synthesis. These are the unusual examples of Zr-MOFs (or MOFs in general) based on phenolic porphyrins, instead of commonly known carboxylate-based types. Representative ZrPP-1 not only exhibits strong acid resistance (pH = 1, HCl) but also remains intact even when immersed in saturated NaOH solution (≈20 m), an exceptionally large range of pH resistance among MOFs. The metallation at the porphyrin core gives rise to materials with enhanced sorption and catalytic properties. In particular, ZrPP-1-Co, with precise and uniform distribution of active centers, exhibits not only high CO2 trapping capability (≈90 cm3 g-1 at 1 atm, 273 K, among the highest in Zr-MOFs) but also high photocatalytic activity for reduction of CO2 into CO (≈14 mmol g-1 h-1 ) and high selectivity over CH4 (>96.4%) without any cocatalyst under visible-light irradiation (λ > 420 nm). Given the strong chemical resistance under extreme alkali conditions, these catalysts can be recycled without appreciable loss of activity. The possible mechanism for photocatalytic reduction of CO2 -to-CO over ZrPP-1-Co is also proposed.

Synthesis of borocarbonitride from a multifunctional Cu(I) boron imidazolate framework.

A functional Cu(I) boron imidazolate framework (BIF) with a ladder-chain structure can not only change to another single-chain structure by incorporating 4,4'-bipyridine, but can also act as a reducing agent to load trimetal Au-Ag-Pd nanoparticles directly; the BIF with loaded noble NPs showed an excellent reduction effect on 4-nitrophenol. Moreover, we obtained a porous borocarbonitride by the direct carbonisation of this low-dimensional BIF. The resulting porous borocarbonitride exhibits fast adsorption behavior for 4-nitrophenol and can be a high-temperature conductor.

Highly selective and sensitive trimethylamine gas sensor based on cobalt imidazolate framework material.

A cobalt imidazolate (im) framework material [Co(im)2]n was employed to use as a trimethylamine (TMA) gas sensor and the [Co(im)2]n sensor can be easily fabricated by using Ag-Pd interdigitated electrodes. Gas sensing measurement indicated that the [Co(im)2]n sensor shows excellent selectivity, high gas response and a low detection limit level of 2 ppm to TMA at 75 °C. The good selectivity and high response to TMA of the sensor based on [Co(im)2]n may be attributed to the weak interaction between the TMA molecules and the [Co(im)2]n framework. That may provide an ideal candidate for detecting freshness of fish and seafood.

Zeolitic imidazolate framework as formaldehyde gas sensor.

Traditional semiconducting metal oxide-based gas sensors are always limited on low surface areas and high operating temperatures. Considering the high surface area and high stability of zeolitic imidazolate framework (ZIF), ZIF-67 (surface area of 1832.2 m(2) g(-1)) was first employed as a promising formaldehyde gas sensor at a low operating temperature (150 °C), and the gas sensor could detect formaldehyde as low as 5 ppm. This work develops a new promising application approach for porous metal-organic frameworks.