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In this work, experiments and comprehensive insights into the proposed covering liquid method to intensify self-preservation effect for methane (CH4) storage are presented. The CH4 hydrate decomposition percentage was 17.6% with the pressure of 0.61 MPa after 12 h at 266.0 K without a covering liquid, which can be reduced to 12.4%, 13.8%, 13.0%, and 8.3% with the pressure of 0.26 MPa, 0.33 MPa, 0.51 MPa, and 0.37 MPa by covering with tetrahydrofuran (THF), cyclopentane (CP), cyclohexane, and n-tetradecane, respectively. When the temperature for CH4 hydrate decomposition was 274.2 K, covering with THF, CP, cyclohexane, and n-tetradecane failed to inhibit CH4 hydrate decomposition. The results suggested that the covering liquid may form a new solid layer (a hydrate layer or other solidified layer) around the CH4 hydrate, which inhibit CH4 transfer below the freezing point of water. However, the new solid layer cannot resist the fast transfer of CH4 from decomposed CH4 hydrate above the freezing point of water. The same phenomenon was also observed in a sodium dodecyl sulfonate (SDS)-dry solution CH4 hydrate formation system. Therefore, the covering method can only intensify the self-preservation effect below the freezing point of water, but cannot generate a self-preservation effect.

The exploitation of highly stable and active catalysts for the conversion of CO2 into valuable fuels is desirable but is a great challenge. Herein, we report that the incorporation of chromophores into metal-organic frameworks (MOFs) could afford robust catalysts for efficient CO2 conversion. Specifically, a porous Nd(III) MOF (Nd-TTCA; TTCA3- = triphenylene-2,6,10-tricarboxylate) was constructed by incorporating one-dimensional Nd(CO2)n chains and TTCA3- ligands, which exhibits a very high stability, retaining its framework not only in the air at 300 °C for 2 h but also in boiling aqueous solutions at pH 1-12 for 7 days. More importantly, Nd-TTCA has achieved a 5-fold improvement in photocatalytic activity for reducing CO2 to HCOOH and a 10-fold improvement in catalytic activity for the cycloaddition of CO2 into cyclic carbonate in comparison to those of H3TTCA itself. This work gives a new strategy to design efficient artificial crystalline catalysts for CO2 conversion.

Efficient generation of synthetic gas (syngas) through the electrochemical reduction of CO2 and H2O is a promising route to realize the conversion and storage of electricity. The production of syngas with a controlled CO/H2 ratio is significant for the subsequent preparation of value-added chemicals. Herein, a guest–host pyrolysis strategy is employed to synthesize Co–C/Nx-based single-site catalytic materials. The as-prepared materials possess a high graphitic degree of carbon, which supports the rapid electron transport and promotes efficient electrochemical reduction reactions. As a result, these materials can serve as excellent electrocatalysts for the production of syngas by the electrochemical reduction of CO2 and H2O, which exhibits high production rates and steady CO/H2 ratio (v : v = 1 : 2) at wide-range electrochemical windows. The faradaic efficiency reaches nearly 100%, and the formation rate reaches as high as 1.08 mol g−1 h−1 at 1.0 V vs. RHE.

Desalination by freezing/thawing method was a very important method to obtain fresh water from sea water. In this work, desalination by freezing/thawing method was conducted with initial sodium chloride of 3.5 wt% in consideration of stirring speed, freezing time and subcooling. The subcooling ranged from 1.2 K to 4 K. The optimum conditions for desalination in this work were stirring speed of 200 r·min−1, freezing time of 120 min, and subcooling of 3 K. The results also showed that sodium chloride cannot be effectively removed by once freezing/thawing process. The maximum removal efficiency of sodium chloride was 64.3%. Two major reasons resulting in the impurity of obtained melted water by freezing/thawing method were proposed. The first reason was the inevitable adhesion of salt solution to the surface of ice, which could be removed easily by distilled water flushing. The second reason was that salt solution was heterogeneously wrapped in the accumulated ice, which was difficult to be removed by distilled water flushing. The liquid flushing method was proposed to verify the conjecture, and the results were in accordance with the two reasons mentioned above. Additional method, such as multiple flushing liquid method, was suggested to be used during the freezing/thawing process for effectively removing sodium chloride, and obtaining fresh water.

It is common that different crystal facets in metal and metal oxide nanocrystals display different catalytic performances, whereas such phenomena have been rarely documented in metal-organic frameworks (MOFs). Herein, we demonstrate for the first time that a nickel metal-organic layer (MOL) exposing rich (100) crystal facets (Ni-MOL-100) shows a much higher photocatalytic CO2 -to-CO activity than the one exposing rich (010) crystal facets (Ni-MOL-010) and its bulky counterpart (bulky Ni-MOF), with a catalytic activity up to 2.5 and 4.6 times more active than Ni-MOL-010 and bulky Ni-MOF, respectively. Theoretical studies reveal that the two coordinatively unsaturated NiII ions with a close distance of 3.50 A on the surface of Ni-MOL-100 enables synergistic catalysis, leading to more favorable energetics in CO2 reduction than that of Ni-MOL-010.

ACE2 (angiotensin-converting enzyme 2) has a multiplicity of physiological roles that revolve around its trivalent function: a negative regulator of the renin-angiotensin system, facilitator of amino acid transport, and the severe acute respiratory syndrome-coronavirus (SARS-CoV) and SARS-CoV-2 receptor. ACE2 is widely expressed, including, in the lungs, cardiovascular system, gut, kidneys, central nervous system, and adipose tissue. ACE2 has recently been identified as the SARS-CoV-2 receptor, the infective agent responsible for coronavirus disease 2019, providing a critical link between immunity, inflammation, ACE2, and cardiovascular disease. Although sharing a close evolutionary relationship with SARS-CoV, the receptor-binding domain of SARS-CoV-2 differs in several key amino acid residues, allowing for stronger binding affinity with the human ACE2 receptor, which may account for the greater pathogenicity of SARS-CoV-2. The loss of ACE2 function following binding by SARS-CoV-2 is driven by endocytosis and activation of proteolytic cleavage and processing. The ACE2 system is a critical protective pathway against heart failure with reduced and preserved ejection fraction including, myocardial infarction and hypertension, and against lung disease and diabetes mellitus. The control of gut dysbiosis and vascular permeability by ACE2 has emerged as an essential mechanism of pulmonary hypertension and diabetic cardiovascular complications. Recombinant ACE2, gene-delivery of Ace2 , Ang 1–7 analogs, and Mas receptor agonists enhance ACE2 action and serve as potential therapies for disease conditions associated with an activated renin-angiotensin system. rhACE2 (recombinant human ACE2) has completed clinical trials and efficiently lowered or increased plasma angiotensin II and angiotensin 1-7 levels, respectively. Our review summarizes the progress over the past 20 years, highlighting the critical role of ACE2 as the novel SARS-CoV-2 receptor and as the negative regulator of the renin-angiotensin system, together with implications for the coronavirus disease 2019 pandemic and associated cardiovascular diseases.

There is a demand to develop molecular catalysts promoting the hydrogen evolution reaction (HER) with a high catalytic rate and a high tolerance to various inhibitors, such as CO and O2 . Herein we report a cobalt catalyst with a penta-dentate macrocyclic ligand (1-Co), which exhibits a fast catalytic rate (TOF=2210 s-1 ) in aqueous pH 7.0 phosphate buffer solution, in which proton transfer from a dihydrogen phosphate anion (H2 PO4 - ) plays a key role in catalytic enhancement. The electrocatalyst exhibits a high tolerance to inhibitors, displaying over 90 % retention of its activity under either CO or air atmosphere. Its high tolerance to CO is concluded to arise from the kinetically labile character of undesirable CO-bound species due to the geometrical frustration posed by the ligand, which prevents an ideal trigonal bipyramid being established.

Low gas hydrate formation rate is one important reason that limits the application of hydrate-based technologies, while development of new kinetic promoter is an alternative method to solve this problem. In this work, oleic acid potassium soap (OPS) was proposed to use as a new potential kinetic promoter to improve methane hydrate formation process. t80 was greater than 360 min when methane hydrate formed in redistilled water, while t80 can decrease to within 100 min with the addition of OPS. Compared OPS with published kinetic promoter of sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), the promoting effect of OPS was better than SDBS, and had similar promoted effect with SDS. In addition, both thermodynamic and kinetic results showed that addition of OPS had little effect of methane hydrates equilibrium conditions. Promoting effect mechanism of OPS was that the double bond and hydrophobic groups enhanced the solubility of methane, which finally improved methane hydrate formation.

Using solar energy to convert CO2 into valuable fuels or chemicals offers a powerful solution to urgent energy and environmental problems. However, the development of efficient and selective catalysts remains a considerable scientific challenge. To address this, catalytically active CoII centers can be anchored into the porous matrix of metal-organic frameworks (MOFs) by utilizing a robust Zr-based MOF (Zr-DMBD) functionalized with freestanding thiol groups to enable efficient post-synthetic metal insertion. The thus-prepared Zr-DMBD-Co MOF solids are modified by well-defined Co-thiolate units and have the capability of photocatalytically converting CO2 into CO with high efficiency and selectivity under visible-light irradiation in a water-containing system. The turnover number and CO selectivity reach as high as 97 941 and 98 %, respectively.

One of the most appealing strategies to address the problems of global warming and energy shortage is to develop clean and sustainable energy source. To this end, considerable efforts have been devoted to designing well-defined catalysts for energy conversion. As an earth-abundant transition metal, nickel has been regarded to be an important catalytic center in molecular catalysts for redox reactions related to energy conversion. This Review focuses on the properties of nickel complexes as molecular catalysts in energy conversion driven by electricity or light, including water splitting and carbon dioxide (CO2) reduction.

Background Nowadays, lung cancer seriously affects human health in the world. Therefore, it is of great significance to develop effective anti-lung cancer drugs. Methods In this work, chalcone derivative HYQ97 was designed via a molecular hybridization strategy. It was synthesized by the cycloaddition in the presence of sodium ascorbate under mild conditions. Lung cancer cell lines were cultured to investigate its antitumor effects in vitro and in vivo. Results HYQ97 inhibited the proliferation of lung cancer cell lines. Specifically, its IC50 value against lung cancer A549 cells was 74.26 nM. It could inhibit heat shock protein 90 (Hsp90) and degrade its client proteins in a dose-dependent manner. Furthermore, HYQ97 suppressed the epithelial mesenchymal transition process and induced apoptosis of A549 cells. Importantly, HYQ97 also had significant inhibitory effects on tumor growth in vivo. Conclusions Chalcone derivative HYQ97 is a promising candidate for lung cancer treatment.

Collective weakness makes strength: A case of multiple π-π stacking interactions stabilizing a porous supramolecular framework., Revealing the contribution of π-π stacking interactions in supramolecular assembly is important for understanding the intrinsic nature of molecular assembly fundamentally. However, because they are much weaker than covalent bonds, π-π stacking interactions are usually ignored in the construction of porous materials. Obtaining stable porous materials that are only dependent on π-π stacking interactions, despite being very challenging, could address this concern. Here, we present a porous supramolecular framework (π-1) stabilized only by intermolecular π-π stacking interactions. π-1 shows good thermal and chemical stability not only in various organic solvents but also in aqueous solution in a broad pH range. Furthermore, featuring one-dimensional channels with dangling thiolate groups, π-1 exhibits excellent Hg2+ removal performance, with adsorption capacity as high as 786.67 mg g−1 and an adsorption ratio as high as 99.998%. In addition, π-1 also shows high adsorption selectivity to Hg2+ in the presence of a series of interfering ions.

The solar-driven CO2 reduction is a challenge in the field of "artificial photosynthesis", as most catalysts display low activity and selectivity for CO2 reduction in water-containing reaction systems as a result of competitive proton reduction. Herein, we report a dinuclear heterometallic complex, [CoZn(OH)L1 ](ClO4 )3 (CoZn), which shows extremely high photocatalytic activity and selectivity for CO2 reduction in water/acetonitrile solution. It achieves a selectivity of 98 % for CO2 -to-CO conversion, with TON and TOF values of 65000 and 1.8 s-1 , respectively, 4, 19, and 45-fold higher than the values of corresponding dinuclear homometallic [CoCo(OH)L1 ](ClO4 )3 (CoCo), [ZnZn(OH)L1 ](ClO4 )3 (ZnZn), and mononuclear [CoL2 (CH3 CN)](ClO4 )2 (Co), respectively, under the same conditions. The increased photocatalytic performance of CoZn is due to the enhanced dinuclear metal synergistic catalysis (DMSC) effect between ZnII and CoII , which dramatically lowers the activation barriers of both transition states of CO2 reduction.

Coordination polymers (CPs) are ideal precursors for synthesizing porous catalysts. However, the direct thermolysis of CPs is prone to generate agglomerates, greatly reducing the electrical conductivity and active sites of their derived catalysts. The construction of well-ordered CP nanostructures is a promising strategy for alleviating the above issue, but it remains challenging. Here, a facile chemical etching approach is developed for the fabrication of well-aligned three-dimensional (3D) bimetallic Prussian blue-analogue nanosheet arrays. Impressively, the derived porous metal oxide (Fe-NiO) acts as a remarkable oxygen evolution reaction (OER) catalyst, which merely requires overpotentials as low as 218 and 270 mV to achieve 10 and 100 mA cm-2 in 1.0 m KOH aqueous solution, respectively. The excellent electrocatalytic performance of Fe-NiO is ascribed to the 3D porous nanosheet array architecture, which endows the bimetallic catalyst with abundant electrocatalytic active sites, enhanced surface permeability, and high electronic conductivity. It is expected that the proposed strategy can pave a new way for fabricating highly efficient electrocatalysts for energy storage and conversion.

Syngas (CO and H2) is an essential raw material for producing various chemicals in industry. The reduction of CO2 in a water-containing system can serve as a more sustainable pathway to obtain syngas than the transformation of fossil fuels, while the modulation of the H2/CO ratios is a challenge. Herein a nickel(II) tripodal complex is employed as a homogeneous electrocatalyst for CO2 and H2O reduction. With this catalyst, selective CO formation with negligible H2 evolution can be accomplished in the presence of 5.0 M H2O in N,N′-dimethylformamide (DMF). By further varying the applied potentials, the H2/CO ratio can be delicately tuned. The catalyst is appreciably robust with a high turnover number of 1.9 × 106 in 1 day operation with negligible deactivation, which can be attributed to the redox innocence of the used ligand. Based on the results of electrochemistry and DFT calculation, the catalytic mechanism is proposed.

Structural modification of a ligand is an effective way to improve the catalytic activity of molecular catalysts for photocatalytic CO2 reduction. In this study, we designed and synthesized three tripodal ligands with different conjugate groups (L1 = tris{2-[(9′ - anthrylmethyl)amino)ethyl}amine, L2 = tris{2-[(1′-naphthylmethyl)amino]ethyl}amine, L3 = tris[2-(benzylamino)ethyl]amine), and their corresponding mononuclear cobalt complexes, [CoL1(OH)]ClO4 (1), [CoL2(OH)]ClO4 (2), and [CoL3(OH)]ClO4 (3). Control experiments showed that 1 and 2 possess higher efficiency than 3 for the photocatalytic CO2-to-CO conversion, with TON and TOF for CO of 58 000 and 1.61 s–1 for 1, and 49 200 and 1.37 s–1 for 2, respectively, greatly higher than those of 3. Compounds 1 and 2 also display higher CO selectivity (≥97%) than 3. Control experiments and DFT calculations revealed that the excellent catalytic performances of 1 and 2 can be ascribed to the extended conjugation substituent in L1 and L2, which endows the CoII ca...

The reduction of carbon dioxide (CO2 ) has been considered as an approach to mitigate global warming and to provide renewable carbon-based fuels. Rational design of efficient, selective, and inexpensive catalysts with low overpotentials is urgently desired. In this study, four cobalt(II) tripodal complexes are tested as catalysts for CO2 reduction to CO in a MeCN/H2 O (4:1 v/v) solution. The replacement of pyridyl groups in the ligands with less basic quinolinyl groups greatly reduces the required overpotential for CO2 -to-CO conversion down to 200-380 mV. Benefitting from the low overpotentials, a photocatalyst system for CO2 -to-CO conversion is successfully constructed, with an maximum turnover number (TON) of 10 650±750, a turnover frequency (TOF) of 1150±80 h-1 , and almost 100 % selectivity to CO. These outstanding catalytic performances are further elucidated by DFT calculations.

A catalyst developed from a CuII complex of (Et4 N)[Cu(pyN2Me2 )(HCO2 )]⋅0.5 CH3 OH⋅H2 O (1⋅0.5 CH3 OH⋅H2 O; pyN2Me2 =bis(2,6-dimethylphenyl)-2,6-pyridinedicarboxamidate(2-)) shows a high activity to catalyze the reduction reaction of CO2 to CO driven by visible light in 4:1 acetonitrile/water (v:v) using [Ru(phen)3 ](PF6 )2 as photosensitizer and TEOA as sacrificial reductant, with a high TON of 9900 and a high CO selectivity of 98 %. The results of isotope labeling experiment, durability tests and energy dispersive spectroscopy reveal that 1 is robust during the photocatalytic process.

The development of readily available, highly efficient and stable electrocatalysts for the oxygen evolution reaction (OER) is extremely significant to facilitate water splitting for the generation of clean hydrogen energy. Layered double hydroxides (LDHs) exhibit promising electrocatalytic performance for the OER. However, their electrical conductivity and active sites should be increased for the preparation of more effective OER electrocatalysts based on LDHs for large-scale applications. Herein, we demonstrate a facile and practical pathway for the hierarchical fabrication of three-dimensional (3D) porous sulphur incorporated NiCoFe LDH nanosheets (S-NiCoFe LDH) on carbon cloth (CC). The as-obtained hierarchically structured S-NiCoFe LDH electrode shows superb electrocatalytic activity and stability for the OER, requiring overpotentials as low as 206 mV and 258 mV to achieve current densities of 10 mA cm−2 and 100 mA cm−2 in 1.0 M KOH solution, respectively, making S-NiCoFe LDH one of the most efficient low-cost electrocatalysts for the OER. The enhanced electrocatalytic performance is attributed to the unique 3D hierarchical nanostructure and sulphur doping, which endow the self-supported S-NiCoFe LDH electrode with abundant active sites and superb electrical conductivity. The strategy expands the possibilities for boosting the catalytic activity of LDH-based OER electrocatalysts.

Developing cheap and earth-abundant catalysts for an efficient and selective reduction of CO2 is a promising approach to cut down the increasing emissions of CO2 and obtain valuable fuels/chemicals simultaneously. Here, we present a dinuclear nickel complex, [Ni2L1](ClO4)4 (1, L1 = 1,2-bis((5,7-dimethyl-1,4,8,11-tetraazacyclotetradecan-6-yl)methyl)benzene), which shows an excellent performance for the electrocatalytic reduction of CO2 to CO, with a Faradaic efficiency of 95%, and turnover number (TON) and turnover frequency (TOF) values of 4.1 × 106 and 190.0 s−1, respectively. Electrochemical experiments and density functional theory (DFT) calculations revealed that the excellent catalytic performance of 1 is attributed to the synergistic catalysis effect between two Ni centers within 1.

Herein, we report a mononuclear Co(II) cryptate which exhibits highly efficient and selective photocatalytic CO2-to-CO conversion in H2O/CH3CN solution. The TON and selectivity reach as high as 51 392 and 98%, respectively.

Hydrogen-bonded organic frameworks (HOFs), a new type of porous material following the metal–organic frameworks (MOFs), covalent organic frameworks (COFs), etc., have emerged as one of the promising candidates in diverse potential applications. In this highlight, we summarize the key progress on HOF-based materials, in which their design, structures, as well as potential applications will be discussed.

The fall armyworm (Spodoptera frugiperda) is a major economic pest in the United States and has recently become a significant concern in African and Asian countries. Due to its increased resistance to current management strategies, including pesticides and transgenic corn, alternative management techniques have become more necessary. Currently, silicon (Si) is being used in many pest control systems due to its ability to increase plant resistance to biotic and abiotic factors and promote plant growth. The current experiments were carried out at the College of Plant Protection, Gansu Agricultural University, Lanzhou, China, to test the effect of Si on lifetable parameters and lipase activity of fall armyworm and vegetative and physiological parameters of maize plants. Two sources of Si (silicon dioxide: SiO2 and potassium silicate: K2SiO3) were applied on maize plants with two application methods (foliar application and soil drenching). The experiment results revealed that foliar applications of SiO2 and K2SiO3 significantly (P≤0.05) increased mortality percentage and developmental period and decreased larval and pupal biomass of fall armyworm. Similarly, both Si sources significantly (P≤0.05) reduced lipase activity of larvae, and fecundity of adults, whereas prolonged longevity of adults. Among plant parameters, a significant increase in fresh and dry weight of shoot, stem length, chlorophyll content, and antioxidant activity was observed with foliar applications of Si. Root fresh and dry weight was significantly (P ≤ 0.05) higher in plants treated with soil drenching of SiO2 and K2SiO3. Moreover, SiO2 performed better for all parameters as compared to K2SiO3 and control treatment. The study conclusively demonstrated a significant negative effect on various biological parameters of fall armyworm when plants were treated with Si, so it can be a promising strategy to control this pest.

The development of efficient and stable photocatalysts in drastic conditions is highly desirable yet remains challenging. Herein, we report an exceptionally stable cerium metal-organic framework (MOF), Ce-TTCA, which can achieve photocatalytic hydrogen (H2) production in both pH = 2 and 12 aqueous solutions using Pt as a cocatalyst (Pt/Ce-TTCA), with H2 production rates of 60.3 and 348.8 μmol g−1 h−1, respectively. More impressively, partial oxidation of Ce3+ to Ce4+ in Ce-TTCA not only extends the light harvesting ability, but also promotes the effective charge separation, thus greatly improving photocatalytic H2 production activity. The Pt/Ce-TTCA-65 with the content of 65 % Ce4+ shows 6-fold improvement of photocatalytic activity than that of Pt/Ce-TTCA without Ce4+, well highlighting that the crucial role of metal oxidation state in photocatalysis. This work represents the first report on regulating MOF photocatalysis for hydrogen production by manipulating the metal oxidation state.

A new monoterpenoid, 7-acetyl-8,9-dihydroxy thymol (1), together with a known one 7,8-dihydroxy-9-buyryl thymol (2), were isolated from the dried flower buds of Lonicera japonica Thunb. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic data analyses. The potential antibacterial effects of these compounds on Staphylococcus aureus, Escherichia coli, Micrococcus luteus, and Bacillus cereus were evaluated. Interestingly, both compounds 1 and 2 exhibited significant antibacterial activities with IC50 values range from 27.64 ± 2.26 to 128.58 ± 13.26 μg/mL.

Presented in this article are the anion-tuning formation, crystal structures and luminescent properties of four coordination polymers of N,N′-di(3-pyridine) oxamide (DPOM), including two one-dimensional (1D) chain/ladder polymers, [Ni(DPOM)(H2O)4]SO4·2H2O (1) and [Cd4(DPOM)6(NO3)8] (2), as well as two 3D coordination polymers, [Zn2(DPOM)(H2O)4(SO4)2] (3) and [Cd2(DPOM)(H2O)4(SO4)2] (4). The results of single crystal X–ray diffraction analyses indicate that in these coordination polymers, DPOM ligand serves as a bridge, connecting metal ions by both terminal pyridine N atoms. 1 is a 1D chain structure formed by the bridge of DPOM. 2 is a 1D ladder-like structure featuring Cd(NO3)2 structural units bridged by DPOM ligands. Both 3 and 4 are 3D pillar-layer structures with the 2D inorganic layer ZnSO4/CdSO4 pillared by DPOM ligands. The results of photoluminescent measurements illustrate that upon excitation, 2–4 can emit fluorescence in 408, 416, and 422 nm in the solid state, respectively.

Three supramolecular compounds based on 1,4-benzeneditetrazole (H2BDT), (NH4)2(BDT) (1), [Mg(H2O)6](HBDT)2·2H2O (2), and [Mg(CH3OH)4(H2O)2](HBDT)2·2CH3OH (3) have been solvothermally synthesized and structurally characterized by single-crystal/powder X-ray diffraction. Structural analyses indicated that these compounds are 3D supramolecular structures stabilized by electrostatic interactions and intermolecular hydrogen bonds. The crystal to crystal transformation between 2 and 3 were investigated. The result showed that 2 is readily transform to 3 after immersed in methanol solution, while 3 can not be converted to 2 after immersed in distilled water solution.

Visible-light driven reduction of CO2 into chemical fuels has attracted enormous interest in the production of sustainable energy and reversal of the global warming trend. The main challenge in this field is the development of efficient, selective, and economic photocatalysts. Herein, we report a Co(II)-based homogeneous catalyst, [Co(NTB)CH3CN](ClO4)2 (1, NTB = tris(benzimidazolyl-2-methyl)amine), which shows high selectivity and stability for the catalytic reduction of CO2 to CO in a water-containing system driven by visible light, with turnover number (TON) and turnover frequency (TOF) values of 1179 and 0.032 s–1, respectively, and selectivity to CO of 97%. The high catalytic activity of 1 for photochemical CO2-to-CO conversion is supported by the results of electrochemical investigations and DFT calculations.

The reactions of Zn(NO3)2·6H2O with mixed ligands of 5-amino-tetrazole (Hatz) and l,2,4,5-benzenetetracarboxylic acid (H4btec) under hydro(solvo)thermal conditions, gave two three-dimensional (3D) porous metal-organic frameworks (MOFs) of {[Zn3(atz)2(btec)(DMF)2]·DMF·2H2O}n (1) and [Zn2(Hprz)(atz)(btec)(H2O)]n (2) in the absence and presence of piperazine (prz), respectively. 1 and 2 were characterized by infrared spectra (IR), elemental analyses (EA) and single-crystal/powder X-ray diffraction. In 1, the adjacent 1D [Zn3(btec)]n2n+ chains are linked together by atz− ligands to form a 3D porous MOF with 1D tetragonal channels filled with coordinated and guest DMF, and lattice water molecules. In 2, the adjacent 2D [Zn2(btec)]n wavelike sheets are pillared through atz− ligands to generate a 3D layered-pillared porous MOF with 1D open channels, which are occupied by coordinated Hprz+ cations and coordinated water molecules. Additionally, thermal stabilities and photoluminescent properties of both compounds in the solid-state at room temperature have been investigated and discussed in detail.

The production of two-dimensional (2D) ultrathin metal-organic framework (MOF) nanosheets with functionalized surfaces is significant for extending their applications. To date, no protocol has been developed yet to solve this problem. Herein, we report a facile, mild, and efficient method to produce 2D monolayer MOF nanosheets with hydrophobic surfaces from layer-pillared 3D MOFs. This approach is based on the replacement of weaker coordinating pillar ligands with stronger coordinating capping ligands with the assistance of a high concentration gradient of the latter. Utilizing this method, the replacement of the 4,4'-bipyridine (bpy) pillars in two cadmium-based layer-pillared MOFs with alkylpyridine derivatives has been achieved, producing 2D MOF nanosheets with monolayer thickness and double-sided hydrophobic surfaces. The resulting hydrophobic 2D MOF nanosheets exhibit good performance for the separation of oil and water.

The photochemical reduction of carbon dioxide (CO2) into valuable chemicals or feedstock is very meaningful for environmental and energy sustainability. Development of efficient, robust and low-cost catalysts is necessary and desirable for their practical application. In this communication, we exploited such a catalyst by anchoring single-Co(II) sites on g-C3N4, which was firstly achieved by the pyrolysis of ultrathin cobalt metal-organic framework (MOF) nanosheets (also called metal-organic layers; MOLs) during the process of g-C3N4 formation. Benefitting from the confinement effect of MOL matrix and the close contact between MOLs and g-C3N4 precursor, the Co(II) sites can be homogeneously and atomically dispersed on the surface of g-C3N4 during the process of g-C3N4 formation. Impressively, this photocatalyst possesses excellent catalytic performance for photochemical CO2-to-CO conversion, with the CO evolution rate as high as 464.1 μmol g−1 h−1, 3 and 222 times higher than those of using bulky Co-MOF and CoCl2 as the cobalt sources, respectively. This work paves a new way to develop the cost-effective photocatalysts containing single-atom sites for clean energy production.

Two metal–organic frameworks (MOFs) {(Me2NH2)[ZnLi(PTCA)(H2O)]}n·n{3DMF·C4H8O2·4H2O} (1) and {(Me2NH2)[ZnLi(PTCA)]}n·n{3DMF·5H2O} (2) have been constructed from Li–Zn clusters and pyrene-1,3,6,8-tetracarboxylic acid (H4PTCA) under solvothermal conditions. Gas sorption measurements have revealed that the pore of desolvated 2 (2d) can strongly interact with H2 and CO2, with high H2 and CO2 adsorption heats of 15.3 and 51.9 kJ/mol, respectively. Furthermore, 2d can selectively adsorb CO2 over N2 and CH4, with high adsorption selectivity of CO2/N2 and CO2/CH4.

A dinuclear cobalt complex [Co2(OH)L1](ClO4)3 (1, L1=N[(CH2)2NHCH2(m-C6H4)CH2NH(CH2)2]3N) displays high selectivity and efficiency for the photocatalytic reduction of CO2 to CO in CH3CN/H2O (v/v=4:1) under a 450 nm LED light irradiation, with a light intensity of 100 mW cm−2. The selectivity reaches as high as 98 %, and the turnover numbers (TON) and turnover frequencies (TOF) reach as high as 16896 and 0.47 s−1, respectively, with the calculated quantum yield of 0.04 %. Such high activity can be attributed to the synergistic catalysis effect between two CoII ions within 1, which is strongly supported by the results of control experiments and DFT calculations.

Five three-dimensional (3D) coordination polymers, {(NiL)[(NiL)(V16O42)]}n·2nH2O (1), [(NiL)3(VO3)6]n·5nH2O (2), [(NiL)3(V6O18)]n·7nH2O (3), [(NiL)3(V8O23)]n (4), and [(NiL)4(V10O29)]n (5), have been obtained by the reaction of the macrocyclic nickel complex [NiL](ClO4)2 (L = 1,4,8,11-tetraazacyclotetradecane) with NH4VO3 under different conditions. Single-crystal X-ray diffraction analyses revealed that the [VO3]– anion assumes diverse species and structures in these five coordination polymers, including the [V16O42]n4n– sheet, [V6O18]6– ring, [VO3]nn– chain, [VO3]nn– sheet, and [V10O29]n8n– chain. The [V16O42]n4n– sheets, [V6O18]6– rings, [VO3]nn– chains, [VO3]nn– sheets, and [V10O29]n8n– chains are linked together through [NiL]2+ bridges to form the 3D frameworks of 1–5. The single-crystal to single-crystal transformation between 2 and desolvated 2 was successfully realized. Electrochemical measurements indicate that 2 and 4 are potential catalysts for water splitting.

Chemical hydrogen storage, endowed with superiorities of safety and efficiency, has been regarded as one of the most promising approaches. The design and synthesis of metallic catalytic system is an key step for development of chemical hydrogen storate materials. In this paper, we report that RhNi nanocatalyst, formed by spontaneously alloying of well-dispersed Rh and Ni NPs, exhibits much higher performance in the catalytic dehydrogenation of hydrous hydrazine.

A cadmium(II) 3-D porous metal–organic framework, (Me2NH2)4[Cd2(TTCA)2Cl2]·7DMF·2Diox·6H2O (1) (TTCA = triphenylene-2,6,10-tricarboxylate, DMF = N,N-dimethylformamide, diox = 1,4-dioxane), has been synthesized through solvothermal conditions. Single-crystal X-ray analysis reveals that the structure of 1 has a two-fold interpenetrating framework with a large solvent-accessible volume of 52% per unit cell. The result of topological analysis shows that 1 is a (3,3)-connected 3-D network with {103} topology. Luminescence tests illustrate that 1 can selectively sense nitroaromatic explosives via a luminescence quenching mechanism.

The gelation ability of melamine was evaluated under various acidic conditions, and the related gelator aggregates were investigated with scanning electron microscopy, transmission electron microscopy, single-crystal X-ray diffraction, thermo-gravimetric analysis, differential scanning calorimetric analysis, rheological experiments, 1H nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and powder X-ray diffraction. It was found that melamine interacted strongly with a number of organic/inorganic acids in water, forming thermal-reversible supramolecular hydrogels with different critical gelator concentrations (CGCs). The CGCs of gelators successively made with salicylic acid, m-hydroxybenzoic acid and p-hydroxybenzoic acid decreased because of the steric hindrance, whereas those related to oxalic acid dihydrate and orthoboric acid presented higher values due to the lack of a phenyl ring in the molecular structures. More interestingly, a unique onium salt, 2,4,6-triamino-1,3,5-triazin-1-ium benzoate dihydrate (TTIBD), was formed via the Lewis acid–base reaction of benzoic acid and melamine. It crystallized in the monoclinic space group C2/c (Z = 8) with lattice parameters a = 21.477 (3) A, b = 10.2253 (14) A, c = 12.3312 (17) A and β = 98.717 (3)°. The formed hydrogel not only exhibited thermo-sensitive characteristics and solid-like behavior, but also showed a solution–gel–crystal transition, being an amorphous-to-crystalline phase transition. By increasing the concentration from 0.04 to 0.12 mol L−1, the gel–solution transition temperature increased from 23.0 to 49.5 °C, and the gel–crystal transition time decreased from 430 to 253 min, but both leveled off upon increasing the concentration. The TTIBD crystal along with the corresponding hydrogel was self-assembled via hydrogen bonds and π–π stacking interactions.

Herein we report a copper-mediated intramolecular aerobic oxidative cyclization of alkynes and sulfonylcrotonates. This method provides simple, efficient and easy to operate access to a variety of highly functionalized naphthyl ketones with excellent functional group tolerance.

The quality of Shanxi aged vinegar (SAV), a famous Chinese vinegar, was improved during its special long-time ageing. SAV samples of different ageing time were analyzed by composition analysis, rheometer, and principal component analysis (PCA). Three main quality indicators of SAV, namely total acidity, soluble solids content and R ratio, and most of composition, including glucose, acetic acid, lactic acid and total polyphenols increased when ageing process prolonged. Newton function and Power law model were fitted to rheological data to investigate the rheological characters: shear viscosity, consistency coefficients and flow behavior index (n). PCA showed the viscosity of SAV had positive relationship with ageing time as well as all composition parameters. Quality including main quality indicators, composition and rheological characters was significantly differenct (p < 0.05) among the SAV in different phases. Thus, the rheological method was a very useful tool to classify the quality of SAV.

Molecular catalysts for electrochemical and photochemical CO2 reduction have developed rapidly during the past two decades. Using non-noble metal (Ni, Co, Mn, Fe, and Cu) complexes as molecular catalyst, numerous catalytic systems have shown good catalytic performance for CO2 reduction. It is useful to draw conclusions from the results of reported works and identify concepts that may provide future frameworks in catalyst design for CO2 reduction. It is well-known that the ligand in molecular complexes is one of the key factors affecting catalytic performance. Modification of the ligand structure has become an important strategy to improve the catalytic performance. This review, beginning with a brief general introduction to molecular catalysis of CO2 reduction, intends to reveal ligand effects of non-noble metal complexes on the catalytic performance for CO2 reduction. The latest progress on both electrocatalytic and photocatalytic CO2 reduction by non-noble metal complexes has been summarized, wherein, emphasis has been placed on the effect of ligands on catalyst efficiency, selectivity and stability. New developments involving immobilization of non-noble metal complexes on solid supports or electrodes have also been discussed. Finally, several constructive suggestions in designing efficient molecular catalysts for CO2 reduction have been put forward.

The electrocatalytic water splitting is considered as a prospect meaning to address the urgent energy and environmental problems. However, the electrocatalytic water splitting is greatly limited by the high overpotentials of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Especially, OER involves a complex multistep proton-coupled electron transfer process, which demands a high overpotential to accelerate this sluggish oxygen evolution kinetics. The high overpotentials for OER significantly decrease the efficiency of the overall water splitting. The OER half reaction has thus become the bottleneck of electrocatalytic overall water splitting. It is vital to synthesize highly active electrocatalysts to reduce the activation energy of the reaction and accelerate the generation of H2 and O2, thereby improving the efficiency of the overall water splitting. Prussian blue analogues (PBAs) are representative cyanide-based coordination polymer materials. PBAs possess open framework structures, large specific surface areas, adjustable metal active sites and uniform catalytic centers, showing promising application in electrocatalytic water splitting. Besides, benefiting from the unique structural features of PBAs, their derived electrocatalysts also have large specific surface areas and uniform active sites. Moreover, PBAs can serve as carbon and nitrogen sources. The doped N can regulate the electronic structure of surface active sites, enhancing the intrinsic activity of electrocatalysts. Therefore, the PBA-derived electrocatalysts also exhibit good catalytic performance for water splitting. In this review, we not only summarize the most recent advances on PBAs and their derivatives as electrocatalysts for water splitting, but also conclude the core scientific challenges faced in water splitting. Finally, we provide perspectives for the future research in this field, including catalyst design, catalytic system establishment and so on.

The development of porous metal-organic frameworks that can retain structural integrity under harsh physical and chemical conditions is essential from the perspective of their use in adsorption, catalysis, and sensors. Herein, a lanthanum carboxylate framework was found to exhibit exceptional stability, not only robust in boiling aqueous solutions at pH 2-12 and in boiling common organic solvents over 24 h but also stable upon ball milling for 1 h. Furthermore, this framework displayed highly selective separation for CO2 over N2 ( Sads = 940), as well as size-dependent selective adsorption behavior of water and alcohols.

Currently, the design and construction of an intelligent stimuli-responsive gel system is still a significant challenge. We present here a new gel system from which the formation of heat-set gels, conventional gels and irreversible heat-set gels can be achieved in aromatic solvents. This gel system is based on two-component gelators containing a succinamic acid derivative (SAD) and a primary alkyl amine (R-NH2). With the increase of temperature to 85 °C, a rarely reported reversible heat-set gel (gel formation with the increase of temperature) is afforded. Upon addition of fatty acids into two-component gelators, a conventional gel (gel formation with the decrease of temperature) is formed. When the fatty acid is replaced with dicarboxylic acid, a new heat-set gel is generated, which is irreversible and thermally super-stable. X-ray diffraction analysis reveals that the formation of a reversible heat-set gel relies on electrostatic interactions, hydrogen bonds, and hydrophobic interactions. These two-component gelators show a perfect gel system for the formation of diverse gels including heat-set gels, conventional gels and irreversible heat-set gels. The tunable strategy demonstrated in this letter may provide a new way for creation of more functional gels in gel science.

A copper(II)-catalyzed cyclization reaction of N-(2-alkynylphenyl)imine was developed. This strategy provided an effective procedure for the synthesis of substituted N-vinylindoles in moderate to good yields.

Solvothermal reaction of Co(II)/Zn(II) salt with 1,2,4,5-benzene tetracarboxylic dianhydride (BTD) leads to the formation of two coordination polymers based on benzene-1,2,4,5-tetracarboxylic acid (H4BTC), [Co2(BTC)(DMA)(H2O)]n (1) (DMA = N,N′-dimethylacetamide) and [Zn4(BTC)2(H2O)6]n·3nH2O (2). Both 1 and 2 have been characterized by infrared spectra (IR), elemental analyses (EA), thermogravimetric analyses (TG) and single-crystal/powder X-ray diffraction (XRD). The results of the single-crystal X-ray diffraction analyses reveal that both compounds are 3D coordination polymers. In 1, 1D Co(II)-carboxylate chains are linked together by the organic moiety of BTC4− ligands, forming a 3D coordination polymer. In 2, 1D Zn-BTC4− ribbons are connected together by [Zn2(H2O)3] building units, generating a 3D porous framework with 1D rectangular channels. Gas sorption measurements reveal that the two compounds can not adsorb N2. Photoluminescent study indicates that 2 exhibits luminescent properties with an emission peak at 527 nm.

Two highly stable dynamic metal–organic frameworks exhibit photochromism, tunable photoluminescence, and selective detection of oxygen, which can be recognised by the naked eye through color changes. Furthermore, they also display selective recognition of benzyl alcohol and halogenated solvents, respectively.

Herein we report that a Cu(II) salt can efficiently catalyze water oxidation in a neutral borate buffer. Studies on the mechanism revealed that the borate anion serves as an oxygen donor in O–O bond formation during the process of water oxidation, assisting in enhancing the catalytic activity of Cu(II).