Synthesizing Interpenetrated Triazine-based Covalent Organic Frameworks from CO2.

Crystalline triazine-based covalent organic frameworks (COFs) are aromatic nitrogen-rich porous materials. COFs typically show high thermal/chemical stability, and are promising for energy applications, but often require harsh synthesis conditions and suffer from low crystallinity. In this work, we propose an environmentally friendly route for the synthesis of crystalline COFs from CO2 molecules as a precursor. The mass ratio of CO2 conversion into COFs formula unit reaches 46.3 %. The synthesis consists of two steps; preparation of 1,4-piperazinedicarboxaldehyde from CO2 and piperazine, and condensation of the dicarboxaldehyde and melamine to construct the framework. The CO2 -derived COF has a 3-fold interpenetrated structure of 2D layers determined by powder X-ray diffraction, high-resolution transmission electron microscopy, and select-area electron diffraction. The structure shows a high Brunauer-Emmett-Teller surface area of 945 m2 g-1 and high stability against strong acid (6 M HCl), base (6 M NaOH), and boiling water over 24 hours. Post-modification of the framework with oxone has been demonstrated to modulate hydrophilicity, and it exhibits proton conductivity of 2.5×10-2  S cm-1 at 85 °C, 95 % of relative humidity.

Metal-Organic Framework-Based Catalysts with Single Metal Sites.

Metal-organic frameworks (MOFs) are a class of distinctive porous crystalline materials constructed by metal ions/clusters and organic linkers. Owing to their structural diversity, functional adjustability, and high surface area, different types of MOF-based single metal sites are well exploited, including coordinately unsaturated metal sites from metal nodes and metallolinkers, as well as active metal species immobilized to MOFs. Furthermore, controllable thermal transformation of MOFs can upgrade them to nanomaterials functionalized with active single-atom catalysts (SACs). These unique features of MOFs and their derivatives enable them to serve as a highly versatile platform for catalysis, which has actually been becoming a rapidly developing interdisciplinary research area. In this review, we overview the recent developments of catalysis at single metal sites in MOF-based materials with emphasis on their structures and applications for thermocatalysis, electrocatalysis, and photocatalysis. We also compare the results and summarize the major insights gained from the works in this review, providing the challenges and prospects in this emerging field.

Single-Atom Catalysts Derived from Metal-Organic Frameworks for Electrochemical Applications.

Single-atom catalysts (SACs) have received tremendous attention due to their extraordinary catalytic performances. The synthesis of this kind of catalysts is highly desired and challenging. In the last few years, metal-organic frameworks (MOFs) have been demonstrated as a promising precursor for fabricating SACs. In this review, the progress and recent advances in the synthesis of MOF-derived SACs and their electrochemical applications are summarized. First, the synthetic approaches based on MOFs and accessible characterization techniques for SACs as well as their advantages/disadvantages are discussed. Then, the electrochemical applications of these MOF-derived SACs including the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), CO2 reduction reaction (CO2 RR), nitrogen reduction reaction (NRR), and other energy-related reactions are reviewed. Finally, insights into the current challenges and future prospects of this field are briefly presented.

Contribution to the mitogenome diversity in Delphacinae: Phylogenetic and ecological implications.

We document the complete (or nearly complete) mitogenomes of 20 Delphacidae taxa, and together with 17 other delphacid mitogenomes currently in GenBank, to reconstruct the phylogeny of the Delphacinae and to investigate mitogenome differences among members of Delphacini, Tropidocephalini and Saccharosydnini. The mitogenomes of the 20 species encode the complete set of 37 genes usually found in animal mitogenomes. The length of complete mitogenomes in Delphacinae ranges from 15,531 to 16,231 bp. The gene order of all newly sequenced mitogenomes are identical, and the mitogenome gene order of Stenocranus matsumurai Metcalf in Stenocraninae has a transposition of tRNAThr. The two-clade system in Tropidocephalini was supported with high value (PP = 1, BS = 100), and the monophyly of Bambusiphaga was recovered in this study. Finally, we found that the host shift from plants with a C3 to a C4 photosynthetic pathway appears to have occurred independently in several clades.

Multiple catalytic sites in MOF-based hybrid catalysts for organic reactions.

Hybrid catalysis provides an effective pathway to improve the catalytic efficiency and simplify the synthesis operation, but multiple catalytic sites are required. Catalysts with multiple functions based on/derived from metal-organic frameworks (MOFs) have received growing attention in organic synthesis due to their wide variety and outstanding designability. This review provides an overview of significant advances in the field of organic reactions by MOF-based hybrid catalysts with emphasis on multiple catalytic sites and their synergies, including inherent sites on host frameworks, sites of MOF composites and metal sites in/on MOF-derived hybrid catalysts.

A Honeycomb-Like Bulk Superstructure of Carbon Nanosheets for Electrocatalysis and Energy Storage.

Superstructures have attracted extensive attention because of their potential applications in materials science and biology. Herein, we fabricate the first centimeter-sized porous superstructure of carbon nanosheets (SCNS) by using metal-organic framework nanoparticles as a template and polyvinylpyrrolidone as an additional carbon source. The SCNS shows a honeycomb-like morphology with wall-sharing carbon cages, in each cavity of which a porous carbon sphere is encapsulated. A single piece of SCNS is directly used as the electrode for a two-electrode symmetrical supercapacitor cell without any binders and supports, benefiting from its advantage in ultra-large geometric size, and the Fe-immobilized SCNS exhibits excellent catalytic performances for oxygen reduction reaction and in a Zn-air battery. This synthetic strategy presents a facile approach for preparing functional SCNS at centimetric scale with controllable morphologies and compositions favoring the fabrication of energy devices.

Fabricating Dual-Atom Iron Catalysts for Efficient Oxygen Evolution Reaction: A Heteroatom Modulator Approach.

Understanding the thermal aggregation behavior of metal atoms is important for the synthesis of supported metal clusters. Here, derived from a metal-organic framework encapsulating a trinuclear FeIII 2 FeII complex (denoted as Fe3 ) within the channels, a well-defined nitrogen-doped carbon layer is fabricated as an ideal support for stabilizing the generated iron nanoclusters. Atomic replacement of FeII by other metal(II) ions (e.g., ZnII /CoII ) via synthesizing isostructural trinuclear-complex precursors (Fe2 Zn/Fe2 Co), namely the "heteroatom modulator approach", is inhibiting the aggregation of Fe atoms toward nanoclusters with formation of a stable iron dimer in an optimal metal-nitrogen moiety, clearly identified by direct transmission electron microscopy and X-ray absorption fine structure analysis. The supported iron dimer, serving as cooperative metal-metal site, acts as efficient oxygen evolution catalyst. Our findings offer an atomic insight to guide the future design of ultrasmall metal clusters bearing outstanding catalytic capabilities.

A Single-Crystal Open-Capsule Metal-Organic Framework.

Micro-/nanocapsules have received substantial attention due to various potential applications for storage, catalysis, and drug delivery. However, their conventional enclosed non-/polycrystalline walls pose huge obstacles for rapid loading and mass diffusion. Here, we present a new single-crystal capsular-MOF with openings on the wall, which is carefully designed at the molecular level and constructed from a crystal-structure transformation. This rare open-capsule MOF can easily load the largest amounts of sulfur and iodine among known MOFs. In addition, derived from capsular-MOF and melamine through pyrolysis-phosphidation, we fabricated a nitrogen-doped capsular carbon-based framework with iron-nickel phosphide nanoparticles immobilized on capsular carbons interconnected by plentiful carbon nanotubes. Benefiting from synergistic effects between the carbon framework and highly surface-exposed phosphide sites, the material exhibits efficient multifunctional electrocatalysis for oxygen evolution, hydrogen evolution, and oxygen reduction, achieving well-qualified assemblies of an overall water splitting (low potential of 1.59 V at 10 mA·cm-2) and a rechargeable Zn-air battery (high peak power density of 250 mW·cm-2 and excellent stability for 500 h), which afford remarkably practical prospects over previously known electrocatalysts.

[Analysis on ecological factors and active components content of wild Dipsacus asper in Chongqing Wulong district].

An HPLC method was developed for the determination of iridoid glycosides (loganin acid, loganin, sweroside) and saponins (asperosaponin Ⅵ) in the wild Dipsacus asper. A total of 108 samples consecutive growing 12 month were collected in 9 plots in Wulong district of Chongqing. Subsequent analysis of the content of loganin acid, loganin, sweroside and asperosaponin Ⅵ was performed by HPLC to evaluate the quality. In addition, 20 climate data provided by the world climate database (http://www.worldclim.org/) was analyzed to deduce the correlation between the growing environment factors and the active ingredient content accumulation of D. asperoides and choose the apposite growing environment for D. asper. The range of active ingredient content in wild D. asper were 0.01%-3.80%(loganin acid), 0.08%-0.62%(loganin), 0.12%-0.78%(sweroside), 0.64%-5.26%(asperosaponin Ⅵ). The highest content of these active ingredients was concentrated from February to April, with 2.64% of loganin acid, 0.36% of loganin), 0.57% of sweroside, and 3.09% of asperosaponin Ⅵ. The method used for determination of the active ingredient content in D. asper was simple and convenient with accurate result. The selection of the quadrats is scientific and reasonable and can be used for the analysis of the contents of the wild D. asper, thus provide a reference for quality evaluation of D. asper and protection of D. asper resources.

[A developmental research on wild Dipsacus asper in Chongqing Wulong district].

In order to study the distribution and dynamics growth of wild Dipsacus asper resources in the Wulong district of Chongqing, 9 sample plots were selected for 12 consecutive months in the natural distribution area of the D. asper in Wulong district by using the sample line + plot survey method to conduct a field survey. The results showed that D.asper was distributed in forest edge wasteland or shrub-grassland, and growbetter with loose yellow-brownsoil or red soil, and poor with lithologic soil or impounded surface water.The growth curve of the plant height from June to July and the ground fresh weight from July to August showed a turning point, it might consume large amounts of nutrients during its flowering period, resulting in the restriction of vegetative growth.The highest temperature in the distribution area of D.asperoides in Wulong district is less than 30 °C, the minimum temperature is about 0 °C, and the rainfall is 1 241-1 392 mm. Its growth environment is no severecold in winter, no heat in summer, and abundant rainfall.The main growth stage of D.asper is from July to October, and the range of root dry rate was 0.162 5-0.239 7 in Xiangkou, 0.154 9-0.223 6 in Baima Mountain, and 0.143 7-0.203 3 Xiannv Mountain. The vegetative growth and dry matter accumulation synchronized in the main growth stage, and the accumulation rate of dry matter was faster than that of vegetative growth. The correlation analysis between indicators and root fresh weight showed that the fresh weight of the aerial part and root fresh weight had the best correlation.

Unique Proton Dynamics in an Efficient MOF-Based Proton Conductor.

Recently, research on metal-organic frameworks (MOFs) serving as a new type of proton conductive material has resulted in many exciting achievements. However, direct observation of a well-established proton-transfer mechanism still remains challenging in MOFs and other crystalline compounds, let alone other conductive materials. Herein we report the solvothermal synthesis of a new proton-conducting MOF, (Me2NH2)[Eu(L)] (H4L = 5-(phosphonomethyl)isophthalic acid). The compound consists of a layered anionic framework [Eu(L)]- and interlayer-embedded counter cations (Me2NH2)+, which interact with adjacent uncoordinated O atoms of phosphonate groups to form strongly (N-H···O) hydrogen-bonded chains aligned parallel to the c-axis. Facile proton transfer along these chains endows the compound with single-crystal anhydrous conductivity of 1.25 × 10-3 S·cm-1 at 150 °C, and water-assisted proton conductivity for a compacted pellet of microcrystalline crystals attains 3.76 × 10-3 S·cm-1 at 100 °C and 98% relative humidity (RH). Proton dynamics (vibrating and transfer) within N-H···O chains of the compound are directly observed using a combination of anisotropic conductivity measurements and control experiments using large single-crystals and pelletized samples, in situ variable-temperature characterization techniques including powder X-ray diffraction (PXRD), single-crystal X-ray diffraction (SCXRD), diffuse reflectance infrared Fourier transform spectrum (DRIFTS), and variable-temperature photoluminescence. In particular, a scarce single-crystal to single-crystal (SCSC) transformation accompanied by proton transfer between an anionic structure (Me2NH2)[Eu(L)] and an identical neutral framework [Eu(HL)] has been identified.

Urea hydrogen bond donor-mediated synthesis of high-index faceted platinum concave nanocubes grown on multi-walled carbon nanotubes and their enhanced electrocatalytic activity.

We have reported, for the first time, in situ growth of high-index {hk0} faceted concave Pt nanocubes on multi-walled carbon nanotubes (CNTs) via an electrochemical method in choline chloride-urea (ChCl-U) based deep eutectic solvents (DESs). Mechanistic studies indicate that a urea hydrogen bond donor (HBD) plays a key role in the formation of concave Pt nanocubes, in which the urea HBD preferentially adsorbs onto the {100} faces and blocks the growth of nanocrystals along the 〈100〉 axis. The as-prepared concave Pt nanocubes are characterized to be enclosed mainly with high-index {710}, {610} and {510} facets. It has been determined that the concave cubic Pt/CNT exhibits higher catalytic activity and stability than the flower-like Pt/CNT and commercial Pt/C catalysts, and this is ascribed to its high density of surface atomic steps and the synergistic effect between the CNT and Pt nanocubes.

[Dynamics of seed rain of Tripterygium hypoglaucum and soil seed bank].

Tripterygium hypoglaucum is an endangered species in arid areas of Xiannvshan Chongqing, China. The dynamic characteristics of seed rain and soil seed bank of T. hypoglaucum were studied in this paper．Results showed that T. hypoglaucum years of mature seeds distribution number up to October; the seed rain occurred from the last ten-day of September to in the first ten-day of November and the peak of scattered seed rain concentrated in the October．The numbers of soil seed bank at 2-5 cm soil layer,mainly concentrated in the 1.5-3.5 m range. T. hypoglaucum seeds to the wind as a force for transmission, the transmission ability is strong, but in the process of natural reproduction, full mature seed rate is low, the soil seed bank seeds seed short-lived factors these were unfavorable for the natural reproduction of T. hypoglaucum population.

Windmill Co4 {Co4 (µ4 -O)} with 16 Divergent Branches Forming a Family of Metal-Organic Frameworks: Organic Metrics Control Topology, Gas Sorption, and Magnetism.

A series of highly connected metal-organic frameworks (MOFs), [Co8 (O)(OH)4 (H2 O)4 (ina)8 ](NO3 )2 ⋅2 C2 H5 OH⋅4 H2 O (1), [Co8 (O)(OH)4 (H2 O)4 (pba)8 ](NO3 )2 ⋅8 C2 H5 OH⋅28 H2 O (2), and [Co8 (O)(OH)4 (H2 O)4 (pbba)8 ](NO3 )2 ⋅guest (3), in which ina=isonicotinate, pba=4-pyridylbenzoate, and pbba=4-(pyridine-4-yl)phenylbenzoate, is reported. These MOFs contain a new secondary building unit (SBU), with a square Co4 (µ4 -O) central unit having the rare µ4 -O(2-) motif, which is decorated by the other four peripheral cobalt atoms through µ3 -OH in a windmill-like shape. This SBU holds 16 divergent connecting organic ligands, pyridyl-carboxylates, to form three different frameworks. The high porosity of desolvated 2 is shown by the efficient gas absorption of N2 , CO2 , CH4 , and H2 . In addition, 1 and 2 exhibit unusual canted antiferromagnetic behavior with spin-glass-like relaxation, with blocking temperatures that are fairly high, 20 K (1) and 10 K (2), for cobalt materials. The relationship between the metal clusters and linkers has been studied, in which the size and rotational degrees of freedom of the ligands are found to control the topology, gas sorption, and magnetic properties.

Dracotangusions A and B, two new sesquiterpenes from Dracocephalum tanguticum Maxim. with anti-inflammatory activity.

Two new guaiane sesquiterpenoids were isolated from the dried aerial parts of Dracocephalum tanguticum Maxim., named as dracotangusions A (1) and B (2), together with four known sesquiterpenoids, which were identified as Curcumenone (3), (4Z,7Z,9Z)-11-Hydroxy-4,7,9-germacratriene-1,6-dione (4), Kobusone (5), and (1S,10S), (4S, 5S)-(+)-germacrone-1(10)-4-diepoxide (6). The structures of isolates were determined by UV, IR, HR-ESI-MS, and NMR analysis. What is noteworthy is that four known sesquiterpenoids were isolated for the first time from the genus of Dracocephalum L. All compounds inhibited the extremely significant difference (p < 0.01) in anti-inflammatory activity, suggesting that these compounds may be promising candidates as an anti-inflammatory agent.

Creating glassy states of dicarboxylate-bridged coordination polymers.

We report the direct formation of dicarboxylate-based coordination polymer glasses through thermal dehydration. The rearrangement of the coordination networks caused by dehydration was monitored by in situ powder X-ray diffraction, infrared spectroscopy, and synchrotron X-ray characterizations. The microporosity and mechanical properties of these glasses were investigated.

Photoluminescent coordination polymer bulk glasses and laser-induced crystallization.

We synthesized luminescent coordination polymer glasses composed of d10 metal cyanides and triphenylphosphine through melt-quenching and mechanical milling protocols. Synchrotron X-ray total scattering measurements and solid-state NMR revealed their one-dimensional chain structures and high structural dynamics. Thermodynamic and photoluminescence properties were tunable by the combination of heterometallic ions (Ag+, Au+, and Cu+) in the structures. The glasses are moldable and thermally stable, and over centimeter-sized glass monoliths were fabricated by the hot-press technique. They showed high transparency over 80% from the visible to near-infrared region and strong green emission at room temperature. Furthermore, the glass-to-crystal transformation was demonstrated by laser irradiation through the photothermal effect of the glasses.

Coordination polymer-forming liquid Cu(2-isopropylimidazolate).

The structure of the melt state of one-dimensional (1D) coordination polymer crystal Cu(isopropylimidazolate) (melting temperature T m = 143 °C) was characterized by DSC, variable temperature PXRD, solid-state NMR (SSNMR), viscoelastic measurements, XAS, and DFT-AIMD calculations. These analyses suggested "coordination polymer-forming liquid" formation with preserved coordination bonds above T m. Variable chain configurations and moderate cohesive interaction in adjacent chains are the keys to the rarely observed polymer-forming liquid. The melt structure is reminiscent of the common 1D organic polymer melts such as entanglement or random coil structures.

Ordered Macroporous Superstructure of Nitrogen-Doped Nanoporous Carbon Implanted with Ultrafine Ru Nanoclusters for Efficient pH-Universal Hydrogen Evolution Reaction.

The electrochemical hydrogen evolution reaction (HER) is an attractive technology for the mass production of hydrogen. Ru-based materials are promising electrocatalysts owing to the similar bonding strength with hydrogen but much lower cost than Pt catalysts. Herein, an ordered macroporous superstructure of N-doped nanoporous carbon anchored with the ultrafine Ru nanoclusters as electrocatalytic micro/nanoreactors is developed via the thermal pyrolysis of ordered macroporous single crystals of ZIF-8 accommodating Ru(III) ions. Benefiting from the highly interconnected reticular macro-nanospaces, this superstrucure affords unparalleled performance for pH-universal HER, with order of magnitude higher mass activity compared to the benchmark Pt/C. Notably, an exceptionally low overpotential of only 13 mV@10 mA cm-2 is required for HER in alkaline solution, with a low Tafel slope of 40.41 mV dec-1 and an ultrahigh turnover frequency value of 1.6 H2 s-1 at 25 mV, greatly outperforming Pt/C. Furthermore, the hydrogen generation rates are almost twice those of Pt/C during practical overall alkaline water splitting. A solar-to-hydrogen system is also demonstrated to further promote the application. This research may open a new avenue for the development of advanced electrocatalytic micro/nanoreactors with controlled morphology and excellent performance for future energy applications.

Bis(3-amino-pyrazine-2-carboxyl-ato-κN,O)diaqua-manganese(II).

The Mn(II) atom in the title compound, [Mn(C(5)H(4)N(3)O(2))(2)(H(2)O)(2)], exhibits an octa-hedral geometry comprising the two O atoms and two N atoms from two 3-amino-pyrazine-2-carboxyl-ate ligands, which act as chelating ligands, and two water mol-ecules. An intra-molecular N-H⋯O hydrogen bond occurs. In the crystal, N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds link adjacent mol-ecules into a three-dimensional network. The mol-ecule lies on a twofold rotation axis.