Solvent-Free Heterogeneous Catalytic Hydrogenation of Polyesters to Diols.

The utilization of carbon resources stored in plastic polymers through chemical recycling and upcycling is a promising approach for mitigating plastic waste. However, most current methods for upcycling suffer from limited selectivity towards a specific valuable product, particularly when attempting full conversion of the plastic. We present a highly selective reaction route for transforming polylactic acid (PLA) into 1,2-propanediol utilizing a Zn-modified Cu catalyst. This reaction exhibits excellent reactivity (0.65 g gcat -1 h-1 ) and selectivity (99.5 %) towards 1,2-propanediol, and most importantly, can be performed in a solvent-free mode. Significantly, the overall solvent-free reaction is an atom-economical reaction with all the atoms in reactants (PLA and H2 ) fixed into the final product (1,2-propanediol), eliminating the need for a separation process. This method provides an innovative and economically viable solution for upgrading polyesters to produce high-purity products under mild conditions with optimal atom utilization.

Neighboring Zn-Zr Sites in a Metal-Organic Framework for CO2 Hydrogenation.

ZrZnOx is active in catalyzing carbon dioxide (CO2) hydrogenation to methanol (MeOH) via a synergy between ZnOx and ZrOx. Here we report the construction of Zn2+-O-Zr4+ sites in a metal-organic framework (MOF) to reveal insights into the structural requirement for MeOH production. The Zn2+-O-Zr4+ sites are obtained by postsynthetic treatment of Zr6(µ3-O)4(µ3-OH)4 nodes of MOF-808 by ZnEt2 and a mild thermal treatment to remove capping ligands and afford exposed metal sites for catalysis. The resultant MOF-808-Zn catalyst exhibits >99% MeOH selectivity in CO2 hydrogenation at 250 °C and a high space-time yield of up to 190.7 mgMeOH gZn-1 h-1. The catalytic activity is stable for at least 100 h. X-ray absorption spectroscopy (XAS) analyses indicate the presence of Zn2+-O-Zr4+ centers instead of ZnmOn clusters. Temperature-programmed desorption (TPD) of hydrogen and H/D exchange tests show the activation of H2 by Zn2+ centers. Open Zr4+ sites are also critical, as Zn2+ centers supported on Zr-based nodes of other MOFs without open Zr4+ sites fail to produce MeOH. TPD of CO2 reveals the importance of bicarbonate decomposition under reaction conditions in generating open Zr4+ sites for CO2 activation. The well-defined local structures of metal-oxo nodes in MOFs provide a unique opportunity to elucidate structural details of bifunctional catalytic centers.

Photoactivation of Cu Centers in Metal-Organic Frameworks for Selective CO2 Conversion to Ethanol.

CO2 hydrogenation to ethanol is of practical importance but poses a significant challenge due to the need of forming one C-C bond while keeping one C-O bond intact. CuI centers could selectively catalyze CO2-to-ethanol conversion, but the CuI catalytic sites were unstable under reaction conditions. Here we report the use of low-intensity light to generate CuI species in the cavities of a metal-organic framework (MOF) for catalytic CO2 hydrogenation to ethanol. X-ray photoelectron and transient absorption spectroscopies indicate the generation of CuI species via single-electron transfer from photoexcited [Ru(bpy)3]2+-based ligands on the MOF to CuII centers in the cavities and from Cu0 centers to the photoexcited [Ru(bpy)3]2+-based ligands. Upon light activation, this Cu-Ru-MOF hybrid selectively hydrogenates CO2 to EtOH with an activity of 9650 µmol gCu-1 h-1 under 2 MPa of H2/CO2 = 3:1 at 150 °C. Low-intensity light thus generates and stabilizes CuI species for sustained EtOH production.

The Galaxy Plot: A New Visualization Tool for Bivariate Meta-Analysis Studies.

Funnel plots have been widely used to detect small-study effects in the results of univariate meta-analyses. However, there is no existing visualization tool that is the counterpart of the funnel plot in the multivariate setting. We propose a new visualization method, the galaxy plot, which can simultaneously present the effect sizes of bivariate outcomes and their standard errors in a 2-dimensional space. We illustrate the use of the galaxy plot with 2 case studies, including a meta-analysis of hypertension trials with studies from 1979-1991 (Hypertension. 2005;45(5):907-913) and a meta-analysis of structured telephone support or noninvasive telemonitoring with studies from 1966-2015 (Heart. 2017;103(4):255-257). The galaxy plot is an intuitive visualization tool that can aid in interpreting results of multivariate meta-analysis. It preserves all of the information presented by separate funnel plots for each outcome while elucidating more complex features that may only be revealed by examining the joint distribution of the bivariate outcomes.

Molecular Iridium Complexes in Metal-Organic Frameworks Catalyze CO2 Hydrogenation via Concerted Proton and Hydride Transfer.

Molecular iridium catalysts immobilized in metal-organic frameworks (MOFs) were positioned in the condensing chamber of a Soxhlet extractor for efficient CO2 hydrogenation. Droplets of hot water seeped through the MOF catalyst to create dynamic gas/liquid interfaces which maximize the contact of CO2, H2, H2O, and the catalyst to achieve a high turnover frequency of 410 h-1 under atmospheric pressure and at 85 °C. H/D kinetic isotope effect measurements and density functional theory calculations revealed concerted proton-hydride transfer in the rate-determining step of CO2 hydrogenation, which was difficult to unravel in homogeneous reactions due to base-catalyzed H/D exchange.

[1,1'-Bis(di-phenyl-phosphan-yl)cobalto-cenium-κ(2) P,P'](η(5)-cyclo-penta-dien-yl){2-[4-(4-ethynylphen-yl)phen-yl]ethynyl-κC}ruthenium(II) hexa-fluorido-phosphate.

In the title compound, [CoRu(C5H5)(C16H9)(C17H14P)2]PF6, the Ru(II) atom is coordinated by a cyclo-penta-dienyl ring in an η(5)-mode, one C atom from a 4,4'-diethynyl-1,1'-biphenyl ligand and two P atoms from a chelating 1,1'-bis-(di-phenyl-phosphan-yl)cobaltocenium ligand, giving a three-legged piano-stool geometry. In the crystal, weak C-H⋯F hydrogen bonds link the complex cations and hexa-fluorido-phosphate anions into a three-dimensional supra-molecular structure.

DNP and ATP regulate the breakdown occurrence in the pulp of Phomopsis longanae Chi-infected longan fruit through modulating the metabolism of membrane lipid.

This study aimed to illustrate how DNP and ATP affected the pulp breakdown occurrence in P. longanae-infected longan and their relationship with the membrane lipid metabolism. Compared with P. longanae-inoculated samples, the pulp of DNP-treated P. longanae-infected longan exhibited higher cellular membrane permeability, breakdown index, activities of PI-PLC, PLD, PC-PLC, LOX, and lipase, and values of SFAs, PA, and DAG, while lower levels of PI, PC, USFAs, IUFA and U/S. However, the opposite findings were observed in ATP-treated P. longanae-infected longan. The data manifested that DNP-increased the pulp breakdown occurrence in P. longanae-inoculated samples was due to the elevated MLDEs activities that reduced the contents of phospholipids (PI, PC) and USFAs, disrupting the cell membrane structures. Nevertheless, ATP decreased the pulp breakdown occurrence in P. longanae-inoculated samples, which was ascribed to the reduced MLDEs activities that raised phospholipids (PI, PC) and USFAs contents, thus maintaining the cell membrane structures.

DNP and ATP regulate the pulp breakdown development in Phomopsis longanae Chi-infected longan fruit through modulating the ROS metabolism.

Compared with the P. longanae-infected longan, the DNP-treated P. longanae-infected fruit represented a higher pulp breakdown index, a higher O2 -. production rate, and a higher MDA content, but the lower activities of APX, SOD and CAT, the lower transcript levels of DlAPX6, DlSOD1, DlSOD2, DlSOD3 and DlCAT1, the lower values of AsA, GSH, flavonoid and total phenolics, a lower scavenging ability of DPPH radical, and a lower value of reducing power. Whereas, the ATP-treated P. longanae-infected samples showed the contrary results. The above findings indicated that the DNP-promoted the pulp breakdown in P. longanae-infected longan was because DNP weakened the capacity of scavenging ROS, raised the O2 -. level, and accelerated the membrane lipids peroxidation. However, the ATP-suppressed the pulp breakdown in P. longanae-infected longan was because ATP improved the capacity of scavenging ROS, reduced the O2 -. level, and reduced the membrane lipids peroxidation.

SiAl composite feedhorn arrays for astrophysical applications: Cryogenic material properties.

A study investigating the physical properties and use of the SiAl composite Controlled Expansion 7 (CE7) for the packaging of silicon bolometric detectors for millimeter-wave astrophysical applications at cryogenic temperatures is presented. The existing interfaces to such detectors are typically made of either ductile metals or micro-machined silicon. As a composite of Si and Al, we find that CE7 exhibits properties of both in ways that may be advantageous for this application. This exploration of the physical properties of CE7 reveals: (a) superconductivity below a critical transition temperature, Tc ∼ 1.2 K; (b) a thermal contraction profile much closer to Si than metal substrates; (c) the relatively low thermal conductivity anticipated for a superconductor, which can be improved by Au-plating; and (d) the feasibility of machining mechanical features with tolerances of ∼25 µm. We further discuss the use of CE7 in the cosmology large angular scale surveyor telescope array, which deployed CE7 in several of its detector focal planes.

Metal-organic frameworks embedded in a liposome facilitate overall photocatalytic water splitting.

Metal-organic frameworks (MOFs) have been studied extensively in the hydrogen evolution reaction (HER) and the water oxidation reaction (WOR) with sacrificial reagents, but overall photocatalytic water splitting using MOFs has remained challenging, principally because of the fast recombination of photo-generated electrons and holes. Here we have integrated HER- and WOR-MOF nanosheets into liposomal structures for separation of the generated charges. The HER-MOF nanosheets comprise light-harvesting Zn-porphyrin and catalytic Pt-porphyrin moieties, and are functionalized with hydrophobic groups to facilitate their incorporation into the hydrophobic lipid bilayer of the liposome. The WOR-MOF flakes consist of [Ru(2,2'-bipyridine)3]2+-based photosensitizers and Ir-bipyridine catalytic centres, and are localized in the hydrophilic interior of the liposome. This liposome-MOF assembly achieves overall photocatalytic water splitting with an apparent quantum yield of (1.5 ± 1)% as a result of ultrafast electron transport from the antennae (Zn-porphyrin and [Ru(2,2'-bipyridine)3]2+) to the reaction centres (Pt-porphyrin and Ir-bipyridine) in the MOFs and efficient charge separation in the lipid bilayers.

Thio linkage between CdS quantum dots and UiO-66-type MOFs as an effective transfer bridge of charge carriers boosting visible-light-driven photocatalytic hydrogen production.

Metal-organic frameworks (MOFs)/semiconductor hybrids have attracted attention in photocatalysis. Herein, we report a new strategy to use thiol-laced UiO-66 (UiO-66-(SH)2) as a porous and functional support for anchoring CdS quantum dots (QDs) (size: 0.5/3 nm). Cd2+ ions are firstly absorbed into the cavities of UiO-66-(SH)2 MOFs via coordinating to the thiol groups in the presence of a base to produce UiO-66-(S-Cd)2, then thiourea is added to form UiO-66-(S-CdS)2 (abbreviated as UiOS-CdS). It is clearly revealed by ultrafast transient absorption spectroscopy that the thio linkage between UiO-66 and CdS acts as an effective transfer bridge of charge carriers, which greatly promotes the interface transfer process of photogenerated electrons and holes, boosting the photocatalytic hydrogen production performance from water splitting. The optimized UiOS-CdS exhibits a photocatalytic H2 production rate of 153.2 µmol h-1 (10 mg of catalyst) under visible-light irradiation (λ > 420 nm) in the absence of nobel metal co-catalyst, corrsponding to an apparent quantum efficiency of 11.9% at 420 nm. This work may provide an effective strategy to construct QDs-linker-MOFs stylephotocatalysts for efficient energy conversion.

Highly Dispersed Ni Catalyst on Metal-Organic Framework-Derived Porous Hydrous Zirconia for CO2 Methanation.

We report the preparation of porous hydrous zirconia by treatment of zirconium-based metal-organic framework (MOF) UiO-66 with a strong base. Microporosity of the original MOF was partially retained in the resultant porous hydrous zirconia. NiII centers were then adsorbed onto the OH-rich hydrous zirconia and in situ converted to highly dispersed Ni0 for CO2 hydrogenation to CH4. The activated catalyst after an induction period showed a turnover frequency of 345 h-1 or a space-time yield of 5851 mmol·gNi-1·h-1 with a CH4 selectivity of over 99%. The catalyst was tested for 100 h on stream, showing only a 4% decrease in activity, and was found to convert atmospheric CO2 to CH4 via CO2 collection through Na2CO3/NaHCO3 cycling. Thermal decomposition of NaHCO3 released CO2 for hydrogenation to CH4, and the resultant Na2CO3 absorbed CO2 from air to form NaHCO3. This work highlights the opportunity in using MOFs as precursors to prepare highly porous metal oxide/hydroxide supports for solid-gas phase catalysis.