Ce-mediated molecular tailoring on gigantic polyoxometalate {Mo132} into half-closed {Ce11Mo96} for high proton conduction.

Precise synthesis of polyoxometalates (POMs) is important for the fundamental understanding of the relationship between the structure and function of each building motif. However, it is a great challenge to realize the atomic-level tailoring of specific sites in POMs without altering the major framework. Herein, we report the case of Ce-mediated molecular tailoring on gigantic {Mo132}, which has a closed structural motif involving a never seen {Mo110} decamer. Such capped wheel {Mo132} undergoes a quasi-isomerism with known {Mo132} ball displaying different optical behaviors. Experiencing an 'Inner-On-Outer' binding process with the substituent of {Mo2} reactive sites in {Mo132}, the site-specific Ce ions drive the dissociation of {Mo2*} clipping sites and finally give rise to a predictable half-closed product {Ce11Mo96}. By virtue of the tailor-made open cavity, the {Ce11Mo96} achieves high proton conduction, nearly two orders of magnitude than that of {Mo132}. This work offers a significant step toward the controllable assembly of POM clusters through a Ce-mediated molecular tailoring process for desirable properties.

Photocatalytic reduction of low-concentration CO2 by metal-organic frameworks.

Direct conversion of diluted CO2 to value-added chemical stocks and fuels with solar energy is an energy-saving approach to relieve global warming and realize a carbon-neutral cycle. The exploration of catalysts with both efficient CO2 adsorption and reduction ability is significant to achieving this goal. Metal-organic frameworks (MOFs) are emerging in the field of low-concentration CO2 reduction due to their highly tunable structure, high porosity, abundant active sites and excellent CO2 adsorption capacity. This highlight outlines the advantages of MOFs for low-pressure CO2 adsorption and the strategies to improve the photocatalytic performance of MOF materials at low CO2 concentrations, including the functionalization of organic ligands, regulation of metal nodes and preparation of MOF composites or derivatives. This paper aims to provide possible avenues for the rational design and development of catalysts with the ability to reduce low-concentration CO2 efficiently for practical applications.

Chiral self-sorting and guest recognition of porous aromatic cages.

The synthesis of ultra-stable chiral porous organic cages (POCs) and their controllable chiral self-sorting at the molecular and supramolecular level remains challening. Herein, we report the design and synthesis of a serial of axially chiral porous aromatic cages (PAC 1-S and 1-R) with high chemical stability. The theoretical and experimental studies on the chiral self-sorting reveal that the exclusive self-recognition on cage formation is an enthalpy-driven process while the chiral narcissistic and self-sorting on supramolecular assembly of racemic cages can be precisely regulated by π-π and C-H…π interactions from different solvents. Regarding the chemical stability, the crystallinity of PAC 1 is maintained in aqueous solvents, such as boiling water, high-concentrated acid and alkali; mixtures of solvents, such as 1 M H2SO4/MeOH/H2O solution, are also tolerated. Investigations on the chiral sensing performance show that PAC 1 enables enantioselective recognition of axially chiral biaryl molecules.

Dynamic Interface with Enhanced Visible-Light Absorption and Electron Transfer for Direct Photoreduction of Flue Gas to Syngas.

The direct usage of CO2 in the flue gas to produce fuels or chemicals is of great significance from energy-saving and low-cost perspectives, yet it is still underexplored. Herein, we report the photoreduction of CO2 from the simulated industrial exhaust by synergistic catalysis of TEOA and a metal-free composite (COF1-g-C3N4) fabricated via covalently grafting COF1 with g-C3N4. The hydrogen bond interaction between TEOA and hydrazine units on COF1 is detected in diluted CO2, which leads to significantly enhanced light absorption in the whole visible-light region. Also, the photo-induced electrons undergo fast transfer from COF1 to g-C3N4. This kind of dynamic interface with enhanced light absorption and electron transfer effects promotes the photosynthetic yield of syngas to 165.6 µmol·g-1·h-1 with the use of simulated exhaust gas as a raw material directly. The photosynthetic yield of syngas ranks among the highest of known metal-free catalysts in diluted CO2. This work provides a general rule for designing efficient catalysts via a controlled catalytic interface and new insights into the role of TEOA in photochemical CO2 reduction.

Transition-Metal-Modified Vanadoborate Clusters as Stable and Efficient Photocatalysts for CO2 Reduction.

Photocatalytic carbon dioxide reduction (CO2RR) is considered to be a promising sustainable and clean approach to solve environmental issues. Polyoxometalates (POMs), with advantages in fast, reversible, and stepwise multiple-electron transfer without changing their structures, have been promising catalysts in various redox reactions. However, their performance is often restricted by poor thermal or chemical stability. In this work, two transition-metal-modified vanadoborate clusters, [Co(en)2]6[V12B18O54(OH)6]·17H2O (V12B18-Co) and [Ni(en)2]6[V12B18O54(OH)6]·17H2O (V12B18-Ni), are reported for photocatalytic CO2 reduction. V12B18-Co and V12B18-Ni can preserve their structures to 200 and 250 °C, respectively, and remain stable in polar organic solvents and a wide range of pH solutions. Under visible-light irradiation, CO2 can be converted into syngas and HCOO- with V12B18-Co or V12B18-Ni as catalysts. The total amount of gaseous products and liquid products for V12B18-Co is up to 9.5 and 0.168 mmol g-1 h-1. Comparing with V12B18-Co, the yield of CO for V12B18-Ni declines by 1.8-fold, while that of HCOO- increases by 35%. The AQY of V12B18-Co and V12B18-Ni is 1.1% and 0.93%, respectively. These values are higher than most of the reported POM materials under similar conditions. The density functional theory (DFT) calculations illuminate the active site of CO2RR and the reduction mechanism. This work provides new insights into the design of stable, high-performance, and low-cost photocatalysts for CO2 reduction.

A thiol-functionalized zirconium metal-organic cage for the effective removal of Hg2+ from aqueous solution.

The mercury ions in waste water have threatened public health and environmental protection. In this sense, novel materials with outstanding performances for removal of Hg2+ are imperative. Herein, we demonstrate a thiol-functionalized zirconium metal-organic cage (MOC-(SH)2) with excellent dispersion displays ideal properties for Hg2+ capture. MOC-(SH)2 exhibits the ability of removing Hg2+ in aqueous solutions with a capacity of 335.9 mgHg2+/gMOC-(SH)2, which surpasses that of classical Zr-based metal-organic framework Uio-66-(SH)2 by 1.89 folds. The higher loading capacity of MOC-(SH)2 is probably owing to the excellent dispersion of the discrete cage, which makes the accessibility of binding sites (thiol) easier. Additionally, 99.6% of Hg2+ can be effectively captured by MOC-(SH)2 with the concentration decreased from 5 to 0.02 ppm reaching the permissible limit for Hg2+, outperforming the performance of Uio-66-(SH)2. The excellent absorption property of MOC-(SH)2 is also achieved in terms of superior selectivity under the presence of competitive metal ions. Meanwhile, the regenerated MOC-(SH)2 can be reused without apparent loss of Hg2+ loading capacity. UV-vis absorption spectra, IR spectra and emission spectra further verified the strong chemical affinity between Hg2+ and the thiol of MOC-(SH)2. The study lays the groundwork for using Zr-MOCs in the removal of toxic metal ions and environmental sustainability.

Synergetic effect of H+ adsorption and ethylene functional groups of covalent organic frameworks on the CO2 photoreduction in aqueous solution.

We prepare a novel COF for CO2 photoreduction with 99.9% CO selectivity in aqueous solution without a cocatalyst. DFT shows that the preferential adsorption of H+ on the COF results in increased CO2 adsorption energy providing an anchoring site of CO2, and with the cooperation of an ethylene group, CO2 reduction is triggered.

A ruthenium/polyoxometalate for efficient CO2 photoreduction under visible light in diluted CO2.

A system containing polyoxometalate ([Co-POM]2-) and [Ru(bpy)3]2+ as constructed for visible-light-induced CO2 conversion to syngas. In diluted CO2, high efficiency of 56.8 mmol g-1 h-1 in syngas production was gained, exceeding that of reported systems with [Ru(bpy)3]2+ participation in similar conditions. Mechanism studies revealed efficient photo-induced charge separation is achieved in the system and CO2 reduction tends to occur on [Ru(bpy)3]2+.

Mn-doped CsPb(Br/Cl)3 mixed-halide perovskites for CO2 photoreduction.

Halide perovskites have been employed as photocatalysts for CO2 photoreduction due to their excellent optical properties and unique electronic structure. However, their photocatalytic performance is relatively poor. Herein, we demonstrate a new strategy with Mn-doped CsPb(Br/Cl)3 mixed-halide perovskites as catalysts to enhance the efficiency of CO2 photoreduction. By tuning the content of Mn, a series of CsPb(Br/Cl)3:Mn perovskites are obtained and show high efficiency in CO2 conversion to CO and CH4. For the optimum catalyst sample, especially, the yields of CO and CH4 reach 1917 µmol g-1 and 82 µmol g-1 which are 14.2 and 1.4 times higher than those of CsPbBr3. This work provides new insights into improving the reactivity of perovskites in CO2 photoreduction.

Polyoxometalates-Based Metal-Organic Frameworks Made by Electrodeposition and Carbonization Methods as Cathodes and Anodes for Asymmetric Supercapacitors.

Hybrid materials have obtained well-deserved attention for energy storage devices, because they show high capacitances and high energy densities induced by the synergistic effect between complementary components. Polyoxometalate-based metal-organic frameworks (POMOFs) possess the abundant redox-active sites and ordered structures of polyoxometalates (POMs) and metal-organic frameworks (MOFs), respectively. Here, an asymmetric supercapacitor (ASC) NENU-5/PPy/60//FeMo/C was fabricated in which both its electrodes are prepared from POMOF precursors. A typical POMOF material, NENU-5, was first connected with polypyrrole (PPy) through electrodeposition to form the cathode material NENU-5/PPy. Another representative POMOFs material, PMo12 @MIL-100, was carbonized to obtain the anode material FeMo/C. Cathode NENU-5/PPy exhibited an extraordinary capacitance of 508.62 F g-1 (areal capacitance: 2034.51 mF cm-2 ). In addition, anode FeMo/C shows excellent cyclic stability attributed to its unique structure. Finally, benefiting from the outstanding capacitances and structural merits of the anode and cathode, assembled asymmetric supercapacitor NENU-5/PPy/60//FeMo/C achieves an energy density of 1.12 mWh cm-3 at a power density output of 27.78 mW cm-3 , as well as a notable life of 10 000 cycles with an capacity retention of 80.62 %. Thus, the unique ASC is strongly competitive in high capacitance, long cycle life, and high energy-required energy storage devices.

A tetraphenylethylene-based covalent organic polymer for highly selective and sensitive detection of Fe3+ and as a white light emitting diode.

A newly prepared tetraphenylethylene-based (TPE-based) covalent organic polymer (COP) named COP-1 exhibits high selectivity for sensing Fe3+ and the limit of detection (LOD) for Fe3+ is 0.42 µM, which is lower than the reported metal-free porous polymers. Furthermore, a WLED is fabricated and the CIE coordinates are (0.32, 0.33), very close to pure white light. The COP-1 shows potential applications in biosensors of Fe3+ and preparation of WLEDs.

A Large-Scale Serological Survey of Toxoplasma gondii Infection Among Persons Participated in Health Screening in Yunnan Province, Southwestern China.

Surveys of Toxoplasma gondii infection in animals have been reported in Yunnan province, southwestern China. However, limited information is available regarding the epidemiology of T. gondii infection among persons participated in health screening in Yunnan. From January 2014 to December 2016, a large-scale and cross-sectional serological survey was conducted to reveal the seroprevalence of T. gondii infection in persons participated in health screening in three major hospitals. A total of 64,533 serum samples were collected and anti-T. gondii antibodies were examined by commercially available enzyme-linked immunosorbent assay kits. The total seroprevalence of T. gondii infection was 6.67% (4306/64,533). Of these, 3721 persons (5.77%, 3721/64,533) were positive for Immunoglobulin G (IgG) only, 473 persons (0.73%, 473/64,533) were positive for Immunoglobulin M (IgM) only, and 112 persons (0.17%, 112/64,533) were positive for both IgG and IgM. Female seroprevalence (6.83%, 3167/46,389) was higher than male (6.28%, 1139/18,144). The highest seroprevalence of T. gondii infection was found in the age range of 41-50 years (10.60%, 228/2150) (p < 0.001). The seroprevalence in 2014, 2015, and 2016 were 6.39% (1083/16,946), 6.24% (1261/20,201), and 7.16% (1962/27,386), respectively. The results showed that T. gondii infection is common in persons participated in health screening in Yunnan province, which has significant public health concern. Thus, improved integrated measures should be executed to prevent and control T. gondii infection humans and animals in Yunnan province.

HKUST-1 Derived Hollow C-Cu2-x S Nanotube/g-C3 N4 Composites for Visible-Light CO2 Photoreduction with H2 O Vapor.

As the main component of syngas, reducing CO2 to CO with high selectivity through photocatalysis could provide a sustainable way to alleviate energy shortage issues. Developing a photocatalytic system with low cost and high performance that is environmentally friendly is the ultimate goal towards CO2 photoreduction. Herein, an efficient and economic three-component heterojunction photocatalyst is designed and fabricated for converting CO2 to CO in the absence of organic sacrificial agents. The heterojunction is made of Cu2-x S nanotubes coated with a carbon layer (C-Cu2-x S) and g-C3 N4 . By using the classical MOF material HKUST-1 as a precursor, hollow tubular-like metal sulfides (C-Cu2-x S) with carbon coating were synthesized and further loaded on g-C3 N4 , forming a three-component heterojunction C-Cu2-x S@g-C3 N4 . The carbon coat in C-Cu2-x S@g-C3 N4 acts as an electron reservoir, which facilitates electron-hole pair separation. The optimized C-Cu2-x S@g-C3 N4 acted as a photocatalyst in CO2 reduction with a high reactivity of 1062.6 µmol g-1 and selectivity of 97 %. Compared with bare g-C3 N4 (158.4 µmol g-1 ) and C-Cu2-x S, the reactivity is nearly 7 and 23-fold enhanced and this CO generation rate is higher than most of the reported Cu2 S or g-C3 N4 composites under similar conditions. The prominent activity may result from enhanced light adsorption and effective charge separation. This work might open up an alternative method for the design and fabrication of high-performance and low-cost photocatalysts for efficiently and durably converting CO2 to CO with high selectivity.

An Amine-Functionalized Zirconium Metal-Organic Polyhedron Photocatalyst with High Visible-Light Activity for Hydrogen Production.

Metal-organic polyhedra (MOPs) are promising candidates for many potential applications; however, their use as photocatalysts for hydrogen production has yet to be developed. Herein, the photocatalytic performance of a water-stable Zr-MOP, ZrT-1-NH2 , was evaluated, for the first time, through photocatalytic hydrogen evolution under visible-light irradiation. ZrT-1-NH2 shows clearly enhanced photocatalytic activity (510.42 µmol g-1 h-1 ) for hydrogen production, in comparison with that of other homogeneous crystalline materials. If platinum nanoparticles were introduced into the photocatalytic system, the hydrogen production efficiency of ZrT-1-NH2 could be further improved. For ZrT-1-NH2 , the conspicuous improvement in photocatalysis can be attributed to efficient electron-hole separation, targeted electron transfer, and excellent recombination suppression. Furthermore, ZrT-1-NH2 shows excellent stability during photocatalytic hydrogen evolution over five continuous runs. This work illustrates that MOP-based photocatalysts hold promise for broad applications in the domain of clean energy.

Metal-Organic Frameworks with Organogold(III) Complexes for Photocatalytic Amine Oxidation with Enhanced Efficiency and Selectivity.

Luminescent organogold(III) complex AuIII with highly emissive triplet excited state was encapsulated in two metal-organic frameworks (MOFs) with different pore sizes and structures (MOF1 and ZJU-28). Compared with the AuIII complex in solution, the resultant composites AuIII @MOF1 and AuIII @ZJU-28 exhibit enhanced emission intensity, lifetime, and quantum yield. Under irradiation, AuIII @MOFs are efficient, selective, and recyclable catalysts for light-induced aerobic C-N bond formation. When used as a heterogeneous catalyst for oxidizing secondary amines to the corresponding imines, AuIII @ZJU-28 achieved high TONs of 876-1548, which are about 2.8-3.5 times higher than that of the homogenous AuIII complex. In addition, different selectivities in oxidizing mixed substrates is realized by means of different host MOFs, and thus encapsulating the AuIII complex in an appropriate MOF allowed the desired product to be obtained. Inherent shortcomings of homogeneous catalysts in cyclic use are also overcome by using composite catalysts, and high conversion of the AuIII @ZJU-28 catalyst was still observed after ten cycles.

Metal-organic framework composites with luminescent pincer platinum(ii) complexes: 3MMLCT emission and photoinduced dehydrogenation catalysis.

Pincer platinum(ii) complexes are well documented to exhibit weak intermolecular interactions in the solid state and 77 K glassy solutions, leading to emissive triplet metal-metal-to-ligand charge transfer (3MMLCT) excited states that often vanish in dilute solutions. In this work, metal-organic framework (MOF) materials are introduced to provide a "solid solution" environment for easy access to 3MMLCT excited states of pincer platinum(ii) complexes. Phosphorescent composites PtII@MOFs (1-4) with matrix-dependent monomers and oligomer emission properties were obtained. These PtII@MOFs are efficient catalysts for photoinduced dehydrogenation reactions.

A luminescent metal organic framework with high sensitivity for detecting and removing copper ions from simulated biological fluids.

The crystal structure of Cd-MOF-74 was obtained for the first time that possesses high sensitivity for the detection of copper ions from water and simulated biological fluids based on changes in luminescent intensity. Furthermore, Cd-MOF-74 could selectively remove Cu2+ from simulated biological fluids that contain Mg2+, Co2+, Zn2+, Fe2+, Ni2+, Na+, and K+. The adsorption capacity of this adsorbent for copper ions reached 189.5 mg g-1 and it quickly adsorbed copper ions within 10 minutes under 10 ppm Cu2+ in the simulated biological system. XPS, PXRD, and gas adsorption measurements revealed that this high sensitivity and selectivity of Cd-MOF-74 resulted from the partial substitution of Cd2+ by Cu2+ in the framework. Although many MOF materials have been employed for sensor or selective adsorption of Cu2+, Cd-MOF-74 is the first example of MOFs showing both capabilities in simulated biological fluids, which represents a pioneering work that extends the applications of MOF materials in the biological field.

A stable Alq3@MOF composite for white-light emission.

A stable mesoporous blue-emitting MOF NENU-521 was successfully constructed. NENU-521 can serve as a host for encapsulating Alq3 to obtain tunable and efficient white-light emission. The Alq3@NENU-521 composite possesses excellent stability and can be used as a promising white phosphor in WLEDs.

An organic-inorganic hybrid photocatalyst based on sandwich-type tetra-Co-substituted phosphotungstates with high visible light photocatalytic activity.

A novel 3D organic-inorganic hybrid framework constructed from tetra-Co(II)-substituted sandwich-type phosphotungstates with a rare 8-connected bcu topology is reported, which exhibited highly efficient photocatalysis activity under visible light and could be used for 5 cycles without any obvious decrease in activity.

Metal-organic framework composites with luminescent gold(iii) complexes. Strongly emissive and long-lived excited states in open air and photo-catalysis.

The encapsulation of luminescent gold(iii) complexes by metal-organic frameworks (MOFs) lays the groundwork for new phosphorescent materials with activities that are not readily achieved by the host MOF materials or gold(iii) complexes alone. In this work, strong phosphorescence with lifetimes of up to ∼50 µs in open air at room temperature has been achieved by incorporation of cationic cyclometalated gold(iii) complexes into MOFs with anionic frameworks to form AuIII@MOFs. The AuIII@MOFs display solid state two-photon-induced phosphorescence. Photo-reduction of methyl viologen to the reduced radical was achieved inside AuIII@MOFs and in the presence of Et3N upon excitation at λ > 370 nm under ambient conditions. These AuIII@MOFs comprise a class of reusable and size-selective heterogeneous photo-catalysts for the aerobic oxidation of secondary amines to imines as well as five other reactions, including oxidative C-H functionalization under aerobic conditions.