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In recent years, single‐atom catalysts (SACs) have received increasing attention in the field of electrochemical CO2RR with their efficient atom utilization efficiency and excellent catalytic performance. However, their low metal loading and the presence of linear relationships for single active sites with simple structures possibly restrict their activity and practical applications. Active site tailoring at the atomic level is a visionary approach to break the existing limitations of SACs. This paper first briefly introduces the synthesis strategies of SACs and DACs. Then, combining previous experimental and theoretical studies, this paper introduces four optimization strategies, namely spin‐state tuning engineering, axial functionalization engineering, ligand engineering, and substrate tuning engineering, for improving the catalytic performance of SACs in the electrochemical CO2RR process by combining previous experimental and theoretical studies. Then it is introduced that DACs exhibit significant advantages over SACs in increasing metal atom loading, promoting the adsorption and activation of CO2 molecules, modulating intermediate adsorption, and promoting C−C coupling. At the end of this paper, we briefly and succinctly summarize the main challenges and application prospects of SACs and DACs in the field of electrochemical CO2RR at present. [ABSTRACT FROM AUTHOR]

Excess CO2 can be effectively converted into valuable fuels and chemicals by electrochemical CO2 reduction, which can help establish a low‐carbon emission economy and solve the current energy crisis. In recent years, metal‐organic frameworks (MOFs), as an emerging multifunctional material with porous structure, high chemical tunability and large specific surface area, has received increasing attention in the field of electrochemical CO2RR. In this paper, we present a comprehensive overview of various MOFs and their derivatives as CO2RR electrocatalysts and analyze their roles in the catalytic process from physical and chemical aspects. In addition, combining experiments and theory, this article also offers a personal view on the electronic structure modulation strategies to improve electrocatalytic performance. The article concludes with an analysis of the challenges in realizing MOFs and their derivatives for electrocatalytic CO2RR applications. [ABSTRACT FROM AUTHOR]

In this paper, CaxZn10‐xFe20 catalysts were prepared by the co‐precipitation method and applied to CO2 hydrogenation. The experimental results show that the CO2 conversion of the catalyst Ca1Zn9Fe20 at a Ca doping amount of 1 mmol can reach 57.91 %, which is 13.5 % more than the CO2 conversion of the catalyst Zn10Fe20. Moreover, the catalyst Ca1Zn9Fe20 has the lowest selectivity for both CO and CH4, with 7.40 % and 6.99 %, respectively. The catalysts were characterized by XRD, N2 adsorption‐desorption, CO2‐TPD, H2‐TPR, and XPS. The results demonstrate that the doping of Ca increases the basic sites on the catalyst surface and thus allows the catalyst to adsorb more CO2 to promote the reaction. Besides, the Ca doping amount of 1 mmol can suppress the formation of graphitic carbon on the catalyst surface and prevent the excess graphitic carbon from covering the active site Fe5C2. [ABSTRACT FROM AUTHOR]

There is increasing demand for superhydrophobic materials, which can be used for separating oil and water efficiently. To avoid secondary pollution, it is desirable to prepare such materials with green technology. Here, we present an environmentally benign method for fabricating superhydrophobic materials by using organic base based solvents in which cellulose can be dissolved and activated. The dissolved cellulose could be chemically modified with a silanization reagent, and the solvent could be recycled after CO2 was removed. The obtained cellulose nanocoating exhibited excellent hydrophobic effects. By spraying it on filter paper (water contact angle (WCA)=165°) for oil and water separation, the separation efficiency of more than 95 % was achieved; ultrasonication of an ordinary sponge in its dispersion (WCA=163°), meant it could be used as an oil absorber. It can also absorb a certain amount of bisphenol A (BPA), with the concentration decreasing by 66 % from the original concentration (0.1 m m). Besides the high separation efficiency, it is resistant to a wide range of pH solutions, which means that it could be used in harsh environments. More importantly, the process is cost-effective, the solvent can be recycled, and the whole process is green. Thus, the activation method provides a green route for the preparation of other cellulose-based materials. [ABSTRACT FROM AUTHOR]

Recent years have seen a growing interest in metal‐free CO2 activation by silylenes, silylones, and silanones. However, compared to mononuclear silicon species, CO2 reduction mediated by dinuclear silicon compounds, especially disilynes, has been less explored. We have carried out extensive computational investigations to explore the mechanistic avenues in CO2 reduction to CO by donor‐stabilized disilyne bisphosphine adduct (R1M) and phosphonium silaylide (R2) using density functional theory calculations. Theoretical calculations suggest that R1M exhibits donor‐stabilized bis(silylene) bonding features with unusual Si−Si multiple bonding. Various modes of CO2 coordination to R1M have been investigated and the coordination of CO2 by the carbon center to R1M is found to be kinetically more facile than that by oxygen involving only one or both the silicon centers. Both the theoretically predicted reaction mechanisms of R1M and R2‐mediated CO2 reduction reveal the crucial role of silicon‐centered lone pairs in CO2 activations and generation of key intermediates possessing enormous strain in the Si−C−O ring, which plays the pivotal role in CO extrusion. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation for syngas can alleviate the pressure of un‐controlled emissions of CO2 and bring enormous economic benefits. Advantageous Ni‐catalysts have good CO2 hydrogenation activity and high CO selectivity merely over 700 °C. Herein, we introduced Cu into Ni catalysts, which were evaluated by H2‐TPR, XRD, BET, in‐situ XPS and CO2‐TPD, and their CO2 hydrogenation activity and CO selectivity were significantly affected by the Ni/Cu ratios, which was rationalized by the synergistic effect of bimetallic catalysts. In addition, the reduction temperatures of studied catalysts apparently affected the CO2 hydrogenation, which were caused by the number and dispersion of the active species. It's found that the Ni1Cu1‐400 had good stability, high CO selectivity (up to 90%), and fast formation rate (1.81×10−5 mol/gcat/s) at 400 °C, which demonstrated a good potential as a superior catalyst for reverse water‐gas shift (RWGS) reaction. [ABSTRACT FROM AUTHOR]

CO2 is the main component of greenhouse gases and also an important carbon source. The hydrogenation of CO2 to methane using Ni‐based catalysts can not only alleviate CO2 emissions but also obtain useful fuels. However, Ni‐based catalysts face one major problem of the sintering of Ni nanoparticles in the process of CO2 methanation. Thus, this work has synthesized a series of efficient and robust nickel silicate catalysts (NiPS−X) with different nickel content derived from nickel phyllosilicate by the hydrothermal method. It was found that the Ni loading plays a critical role in the structure and catalytic performance of the NiPS−X catalysts. The catalytic performance gradually increases with the increase of Ni loading. In particular, the highly dispersed NiPS‐1.6 catalyst with a high Ni loading of 34.3 wt% could obtain the CO2 conversion greater than 80%, and the methane selectivity was close to 100% for 48 h at 330 °C and the GHSV of 40,000 mL g−1 h−1. The excellent catalytic property can be assigned to the high dispersion of Ni nanoparticles and the strong interaction between the active component and the carrier, which is derived from a unique layered silicate structure with lots of nickel phyllosilicate and a large number of Lewis acid sites. [ABSTRACT FROM AUTHOR]

The term "covalent organic framework" (COF) refers to a class of porous organic polymeric materials made from organic building blocks that have been covalently bonded. The preplanned and predetermined bonding of the monomer linkers allow them to demonstrate directional flexibility in two‐ or three‐dimensional spaces. COFs are modern materials, and the discovery of new synthesis and linking techniques has made it possible to prepare them with a variety of favorable features and use them in a range of applications. Additionally, they can be post‐synthetically altered or transformed into other materials of particular interest to produce compounds with enhanced chemical and physical properties. Because of its tunability in different chemical and physical states, post‐synthetic modifications, high stability, functionality, high porosity and ordered geometry, COFs are regarded as one of the most promising materials for catalysis and environmental applications. This study highlights the basic advancements in establishing the stable COFs structures and various post‐synthetic modification approaches. Further, the photocatalytic applications, such as organic transformations, degradation of emerging pollutants and removal of heavy metals, production of hydrogen and Conversion of carbon dioxide (CO2) to useful products have also been presented. Finally, the future research directions and probable outcomes have also been summarized, by focusing their promises for specialists in a variety of research fields. [ABSTRACT FROM AUTHOR]

A new strategy involving the computer-assisted design of substituted imidazolate-based ionic liquids (ILs) through tuning the absorption enthalpy as well as the basicity of the ILs to improve SO2 capture, CO2 capture, and SO2/CO2 selectivity was explored. The best substituted imidazolate-based ILs as absorbents for different applications were first predicted. During absorption, high SO2 capacities up to ≈5.3 and 2.4 mol [ABSTRACT FROM AUTHOR]

Bi‐based electrocatalysts have been widely investigated in the CO2 reduction reaction (CO2RR) for the formation of formate. However, it remains a challenge to achieve high Faradaic efficiency (FE) and industrial current densities at low overpotentials for obtaining both high formate productivity and energy efficiency (EE). Herein, we report an Ag−Bi2O3 hybrid nanofiber (Ag−Bi2O3) for highly efficient electrochemical reduction of CO2 to formate. Ag−Bi2O3 exhibits a formate FE of >90% for current densities from −10 to −250 mA ⋅ cm−2 and attains a yield rate of 11.7 mmol ⋅ s−1 ⋅ m−2 at −250 mA ⋅ cm−2. Moreover, Ag−Bi2O3 increased the EE (52.7%) by nearly 10% compared to a Bi2O3 only counterpart. Structural characterization and in‐situ Raman results suggest that the presence of Ag induced the conversion of Bi2O3 from a monoclinic phase (α‐Bi2O3) to a metastable tetragonal phase (β‐Bi2O3) and accelerated the formation of active metallic Bi at low overpotentials (at > −0.3 V), which together contributes to the highly efficient formate formation. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) is an abundant, inexpensive, renewable C1 resource and the main component of greenhouse gas, thereby the research for its sustainable and efficient conversion has received notable attention in recent years. Electrochemical organic synthesis, as a green and efficient synthetic method, is convinced to be an ideal approach for CO2 utilization. In this review, recent advances in electrocarboxylation with CO2 were summarized through different reaction types, which would disclose the great potential of electrocarboxylation in green organic synthesis. [ABSTRACT FROM AUTHOR]

A silver(I)-catalyzed three-component reaction of propargylic alcohols, CO2, and monohydric alcohols was successfully developed for the synthesis of β-oxopropyl carbonates. As such, a series of β-oxopropyl carbonates were exclusively produced in excellent yields (up to 98 %), even under atmospheric pressure of CO2. The silver catalyst works efficiently for both the carboxylative cyclization of propargylic alcohols with CO2 and subsequent transesterification of α-alkylidene cyclic carbonates with monohydric alcohols; thus this tandem process performs smoothly under mild conditions. This work provides a versatile and thermodynamically favorable approach to dissymmetric dialkyl carbonates. [ABSTRACT FROM AUTHOR]

Carboxylation Transition metal ‐ promoted carboxylation of various organic compounds has attracted much attention, and various types of reactions have been reported. In their Full Paper on page   1170   ff., which is featured on the Back Cover, Nozomi Saito, Zhongdong Sun, and Yoshihiro Sato report on the nickel(0) ‐ promoted carboxylation of aryl ynol ether that proceed in a highly regioselective manner to produce α ‐ substituted β ‐ aryloxyacrylic acid derivatives. Such derivatives could be transformed into the corresponding optically active β ‐ aryloxypropionic acid derivatives via rhodium ‐ catalyzed asymmetric hydrogenation. [ABSTRACT FROM AUTHOR]

Microporous metal–organic frameworks (MMOFs) may find use in carbon dioxide capture and sequestration. In their Full paper on page 778   ff., featured on the Inside Cover, Heping Zeng, Jing Li et al. report that functionalization of two MOF structures by a methyl group leads to two opposing and competitive effects on CO2 adsorption: enhanced CO2 affinity and reduced porosity. When the positive effect is dominant in the competition, enhanced CO2 affinity overrides the loss induced by pore and surface ‐ area reduction, and thereby facilitates the CO2 uptake capacity of the framework. Furthermore, the authors show that the methyl ‐ functionalized compounds exhibit high separation capability for CO2 over other small gases including CH4, CO, N2, and O2. [ABSTRACT FROM AUTHOR]

We investigated the CO2 adsorption and electrochemical conversion behavior of triazole‐based C3N5 nanorods as a single matrix for consecutive CO2 capture and conversion. The pore size, basicity, and binding energy were tailored to identify critical factors for consecutive CO2 capture and conversion over carbon nitrides. Temperature‐programmed desorption (TPD) analysis of CO2 demonstrates that triazole‐based C3N5 shows higher basicity and stronger CO2 binding energy than g‐C3N4. Triazole‐based C3N5 nanorods with 6.1 nm mesopore channels exhibit better CO2 adsorption than nanorods with 3.5 and 5.4 nm mesopore channels. C3N5 nanorods with wider mesopore channels are effective in increasing the current density as an electrocatalyst during the CO2 reduction reaction. Triazole‐based C3N5 nanorods with tailored pore sizes exhibit CO2 adsorption abilities of 5.6–9.1 mmol/g at 0 °C and 30 bar. Their Faraday efficiencies for reducing CO2 to CO are 14–38% at a potential of −0.8 V vs. RHE. [ABSTRACT FROM AUTHOR]

To overcome the challenges of global warming and environmental pollution, it is necessary to reduce the concentration of carbon dioxide (CO2) in the atmosphere, which is mainly accumulated in the air through the burning of fossil fuels. Therefore, the development of environmentally friendly strategies to capture carbon dioxide and convert it into value‐added products offers a promising way forward for reducing carbon dioxide concentration in the atmosphere. In this context, POPs (porous organic polymers) have shown great potential as CO2 selective adsorbents due to their high specific surface area, chemical stability, nanoscale porosity and structural diversity, as well as POPs based heterogeneous catalysts for CO2 conversion. This review provides a concise account of preparation methods of various POPs, challenges and current development trends of POPs in photocatalytic CO2 reduction, electrocatalytic CO2 reduction and chemical CO2 conversion. [ABSTRACT FROM AUTHOR]

The reduction of carbon dioxide (CO2) into value‐added fuels using an electrochemical method has been regarded as a compelling sustainable energy conversion technology. However, high‐performance electrocatalysts for CO2 reduction reaction (CO2RR) with high formate selectivity and good stability need to be improved. Earth‐abundant Bi has been demonstrated to be active for CO2RR to formate. Herein, we fabricated an extremely active and selective bismuth nanosheet (Bi‐NSs) assembly via an in situ electrochemical transformation of (BiO)2CO3 nanostructures. The as‐prepared material exhibits high activity and selectivity for CO2RR to formate, with nearly 94% faradaic efficiency at −1.03 V (versus reversible hydrogen electrode (vs. RHE)) and stable selectivity (>90%) in a large potential window ranging from −0.83 to −1.18 V (vs. RHE) and excellent durability during 12 h continuous electrolysis. In addition, the Bi‐NSs based CO2RR/methanol oxidation reaction (CO2RR/MOR) electrolytic system for overall CO2 splitting was constructed, evidencing the feasibility of its practical implementation. [ABSTRACT FROM AUTHOR]

Anatase TiO2 with co‐exposed (001) and (101) surfaces [(001)‐(101)‐TiO2], as a semiconductor photocatalyst in crystal plane control engineering, has become a research hotspot in environmental purification and energy conversion due to its strong physicochemical stability, non‐toxic and harmless, and low production cost. This review briefly introduces the basic principles and influencing factors of [(001)‐(101)‐TiO2]. On this basis, the effect of heterostructures formed by different materials and modification methods on its photocatalytic activity are elaborated in detail. Mainly formed heterostructures mentioned in this review include oxygen vacancy/Ti3+‐[(001)‐(101)‐TiO2] heterostructures, noble metal‐[(001)‐(101)‐TiO2] heterostructures, metal sulfide‐[(001)‐(101)‐TiO2] heterostructures, metal oxide‐[(001)‐(101)‐TiO2] heterostructures and carbon material‐[(001)‐(101)‐TiO2] heterostructures. The light absorption range and charge separation mechanism of (001)‐(101)‐TiO2 after modification are discussed. Moreover, the application of photocatalytic redox reaction in simulating photosynthesis to prepare new energy (hydrogen evolution and CO2 reduction), environmental purification and sterilization is introduced in detail. Finally, various measures of designing (001)‐(101)‐TiO2 nanostructures for further applications in energy production and environmental remediation are discussed. [ABSTRACT FROM AUTHOR]

The potential of Scenedesmus dimorphus microalgae for CO2 biofixation and lipid biosynthesis for bioenergy applications was evaluated in this study. Batch experiments were conducted using synthetic tertiary municipal wastewater samples at several nitrogen to phosphorus (NP) ratios (1 : 1 to 8 : 1) and CO2 concentrations (∼0%, 2%, 4%, and 6% CO2 in supplied air). Scenedesmus dimorphus was cultivated for 25 days and the growth is highly dependent on the CO2 concentration and the NP ratio. An NP ratio of 2 : 1 produces a biomass yield of 733 mg/L when the microalga culture was supplied with air enriched with 2% CO2. The maximum CO2 biofixation rate of 49.6 mg L−1 d−1 is at an NP ratio of 8 : 1 with 4% CO2. A colorimetric technique depending on sulpho‐phospho‐vanillin (SPV) was utilized for the determination of the intracellular lipid content. The highest lipid content of 31.6% as the dry weight of the biomass is at an NP ratio of 1 : 1 and 6% CO2. These results indicate that supplementation of suitable CO2 with favorable NP ratio has a considerable effect on lipid accumulation in the microalgae Scenedesmus dimorphus biomass. [ABSTRACT FROM AUTHOR]

The concentration of carbon dioxide (CO2) in the atmosphere is increasing at an alarming rate resulting in undesirable environmental issues. To mitigate this growing concentration of CO2, selective carbon capture and storage/sequestration (CCS) are being investigated intensively. However, CCS technology is considered as an expensive and energy‐intensive process. In this context, selective carbon capture and utilization (CCU) as a C1 feedstock to synthesize value‐added chemicals and fuels is a promising step towards lowering the concentration of the atmospheric CO2 and for the production of high‐value chemicals. Towards this direction, several strategies have been developed to convert CO2, a Greenhouse gas (GHG) into useful chemicals by forming C−N, C−O, C−C, and C−H bonds. Among the various CO2 functionalization processes known, the cycloaddition of CO2 to epoxides has gained considerable interest owing to its 100% atom‐economic nature producing cyclic carbonates or polycarbonates in high yield and selectivity. Among the various classes of catalysts studied for cycloaddition of CO2 to cyclic carbonates, porous metal‐organic frameworks (MOFs) have gained a special interest due to their modular nature facilitating the introduction of a high density of Lewis acidic (LA) and CO2‐philic Lewis basic (LB) functionalities. However, most of the MOF‐based catalysts reported for cycloaddition of CO2 to respective cyclic carbonates in high yields require additional co‐catalyst, say tetra‐n‐butylammonium bromide (TBAB). On the contrary, the co‐catalyst‐free conversion of CO2 using rationally designed MOFs composed of both LA and LB sites is relatively less studied. In this review, we provide a comprehensive account of the research progress in the design of MOF based catalysts for environment‐friendly, co‐catalyst‐free fixation of CO2 into cyclic carbonates. [ABSTRACT FROM AUTHOR]

A mild and easy to perform multicomponent coupling involving phosphines, arynes generated from 2‐(trimethylsilyl)aryl triflates, and CO2 allowing the transition‐metal‐free synthesis of zwitterionic phosphonium benzoates has been developed. The reaction proceeds via the generation of 1 : 1 zwitterionic intermediates from phosphines and arynes followed by the interception with CO2 to deliver the carboxylates in moderate to good yields instead of the anticipated benzooxaphosphol‐3(1H)‐ones. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 holds great promise for lowering the concentration of CO2 in the Earth′s atmosphere. However, several challenges have hindered the commercialization of this technology, including energy efficiency, the solubility of CO2 in the aqueous phase, and electrode stability. In this Minireview, we highlight and summarize the main advantages and limitations that metal–organic frameworks (MOFs) may offer in this field of research, either when used directly as electrocatalysts or when used as catalyst precursors. [ABSTRACT FROM AUTHOR]

A convenient photocatalyst‐free method for the synthesis of redox‐active 1,2‐dihydro‐3H‐indazol‐3‐one derivatives from (2‐nitroaryl)methanol and amines was developed. The reaction proceeded efficiently at room temperature by irradiation of UV light under CO2 atmosphere (1.0 atm, flow) without any photocatalysts or additives. This mild, operationally simple method shows wide functional tolerance. The carbamate formed in situ from CO2 and amine is proposed to be the key of this reaction. Some of these compounds synthesized by the present method were found to exhibit high anticancer activities, which can lower the viability of cancerous cell lines such as HeLa, MCF‐7 and U87. [ABSTRACT FROM AUTHOR]

Abstract: Here we report a partially oxidized palladium nanodot (Pd/PdOx) catalyst with a diameter of around 4.5 nm. In aqueous CO2‐saturated 0.5  m KHCO3, the catalyst displays a Faradaic efficiency (FE) of 90 % at −0.55 V vs. reversible hydrogen electrode (RHE) for carbon monoxide (CO) production, and the activity can be retained for at least 24 h. The improved catalytic activity can be attributed to the strong adsorption of CO2.− intermediate on the Pd/PdOx electrode, wherein the presence of Pd2+ during the electroreduction reaction of CO2 may play an important role in accelerating the carbon dioxide reduction reaction (CO2RR). This study explores the catalytic mechanism of a partially oxidized nanostructured Pd electrocatalyst and provides new opportunities for improving the CO2RR performance of metal systems. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical reduction of carbon dioxide (CO2) driven by renewable electricity to give chemicals and fuels is considered an ideal approach that can alleviate both carbon emission and energy tension stress. High‐value chemicals such as oxygenates can be effectively produced from the electroreduction of CO2, and this is highly attractive to promote the economy and applicability of CO2 utilization. This review focuses on recent advancements in the electrochemical reduction of CO2 to formic acid, methanol, ethanol, acetic acid, and other oxygenates. The principles of the process, influencing factors, and typical catalysts are summarized. On the basis of the aforementioned discussions, we present future prospects for further development of the electroreduction of CO2 to oxygenates. [ABSTRACT FROM AUTHOR]

Abstract: Defect‐free mixed‐matrix membranes (MMMs) were prepared by incorporating hydrophilic metal‐organic polyhedra (MOPs) into cross‐linked polyethylene oxide (XLPEO) for efficient CO2 separation. Hydrophilic MOPs with triethylene glycol pendant groups, which were assembled by 5‐tri(ethylene glycol) monomethyl ether isophthalic acid and CuII ions, were uniformly dispersed in XLPEO without particle agglomeration. Compared to conventional neat XLPEO, the homogenous dispersion of EG3‐MOPs in XLPEO enhanced CO2 permeability of MMMs. Upon increasing the amount of EG3‐MOPs, the membrane performance such as CO2/N2 selectivity was steadily improved because of unsaturated CuII sites at paddle‐wheel units, which was confirmed by Cu K‐edge XANES and TPD analysis. Therefore, such defect‐free MMMs with unsaturated metal sites would contribute to enhance CO2 separation performance. [ABSTRACT FROM AUTHOR]

Density functional theory calculations were used to investigate the three possible modes of activation for the coupling of CO2 with alkynyl indoles in the presence of a guanidine base. The first of these mechanisms, involving electrophilic activation, was originally proposed by Skrydstrup et al. ( Angew. Chem. Int. Ed. 2015, 54, 6682). The second mechanism involves the nucleophilic activation of CO2. Both of these electrophilic and nucleophilic activation processes involve the formation of a guanidine-CO2 zwitterion adduct. We have proposed a third mechanism involving the bifunctional activation of the bicyclic guanidine catalyst, allowing for the simultaneous activation of the indole and CO2 by the catalyst. We demonstrated that a second molecule of catalyst is required to facilitate the final cyclization step. Based on the calculated turnover frequencies, our newly proposed bifunctional activation mechanism is the most plausible pathway for this reaction under these experimental conditions. Furthermore, we have shown that this bifunctional mode of activation is consistent with the experimental results. Thus, this guanidine-catalyzed reaction favors a specific-base catalyzed mechanism rather than the CO2 activation mechanism. We therefore believe that this bifunctional mechanism for the activation of bicyclic guanidine is typical of most CO2 coupling reactions. [ABSTRACT FROM AUTHOR]

A direct synthesis of carbamates from amines and carbon dioxide in the presence of Ti(OR)4 (R= nBu ( 1), Me ( 2), Et ( 3), nPr ( 4)) was investigated. Aniline was reacted with titanium n-butoxide ( 1) in the presence of carbon dioxide (5 MPa) to give the corresponding n-butyl N-phenylcarbamate (BPC) in nearly quantitative yield (99 %) within 20 min. Furthermore, 1 could be regenerated upon reaction with n-butanol during water removal. The recovered 1 could then be reused in a subsequent reaction. [ABSTRACT FROM AUTHOR]

Four dinuclear lanthanide mesocates were fabricated through a spontaneous self-assembly method, and the formation of these complexes was well studied by their absorption and emission spectra. These stable complexes were also found to exhibit superior performance in catalyzing the coupling reaction between epoxides and CO2 with excellent recyclability. Moreover, the catalysts could be prepared on large scale. Moreover, the Yb and Lu complexes featured emissions in the near-infrared and visible regions, respectively, and their intensities and lifetimes could be used for identification purposes. Thus, this new approach can be used to construct promising lanthanide complexes as efficient catalysts and it identifies the possibility to better study a catalytic reaction with a luminescent catalyst. [ABSTRACT FROM AUTHOR]

Sustainable carbon materials have received particular attention in CO2 capture and storage owing to their abundant pore structures and controllable pore parameters. Here, we report high-surface-area hierarchically porous N-doped carbon microflowers, which were assembled from porous nanosheets by a three-step route: soft-template-assisted self-assembly, thermal decomposition, and KOH activation. The hydrazine hydrate used in our experiment serves as not only a nitrogen source, but also a structure-directing agent. The activation process was carried out under low (KOH/carbon=2), mild (KOH/carbon=4) and severe (KOH/carbon=6) activation conditions. The mild activated N-doped carbon microflowers (A-NCF-4) have a hierarchically porous structure, high specific surface area (2309 m2 g−1), desirable micropore size below 1 nm, and importantly large micropore volume (0.95 cm3 g−1). The remarkably high CO2 adsorption capacities of 6.52 and 19.32 mmol g−1 were achieved with this sample at 0 °C (273 K) and two pressures, 1 bar and 20 bar, respectively. Furthermore, this sample also exhibits excellent stability during cyclic operations and good separation selectivity for CO2 over N2. [ABSTRACT FROM AUTHOR]

The CH bond carboxylation of various aromatic compounds with CO2 was achieved by the deprotonative alumination with a mixed alkyl amido lithium aluminate compound iBu3Al(TMP)Li followed by the NHC-copper-catalyzed carboxylation of the resulting arylaluminum species, which afforded the corresponding carboxylation products in high yield and high selectivity. In addition to benzene derivatives, heteroarenes such as benzofuran, benzothiophene, and indole derivatives are also suitable substrates. Functional groups such as Cl, Br, I, vinyl, amide, and CN could survive the reaction conditions. Some key reaction intermediates such as the copper aryl and isobutyl complexes and their carboxylation products were isolated and structurally characterized by X-ray crystallographic analyses, thus offering important information on the reaction mechanism. [ABSTRACT FROM AUTHOR]

Reactions of meso-bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) with CuI species in the presence of NaBH4 afforded di- and tetranuclear copper hydride complexes, [Cu2(μ-H)(μ-dpmppm)2]X ( 1) and [Cu4(μ-H)2(μ4-H)(μ-dpmppm)2]X ( 2) (X=BF4, PF6). Complex 1 undergoes facile insertion of CO2 (1 atm) at room temperature, leading to a formate-bridged dicopper complex [Cu2(μ-HCOO)(dpmppm)2]X ( 3). The experimental and DFT theoretical studies clearly demonstrate that CO2 insertion into the Cu2(μ-H) unit occurred with the flexible dicopper platform. Complex 2 also undergoes CO2 insertion to give a formate-bridged complex, [Cu4(μ-HCOO)3(dpmppm)2]X, during which the square Cu4 framework opened up to a linear tetranuclear chain. [ABSTRACT FROM AUTHOR]

Methylene-linked bis( N, N′-di- tert-butylimidazol-2-ylidene) 1 reacted with diethylzinc to give dinuclear zinc ethyl compound 2, which contains a formally anionic bis(carbene) ligand as a result of deprotonation of the methylene bridge. The reaction of 2 with PhSiH3 gave the phenylsilyl compound 3. The zinc hydride 4 was obtained by the reaction of 2 with LiAlH4 or Ph3SiOH followed by treatment with PhSiH3. X-ray diffraction studies show that compounds 2, 3, and 4 all have a similar dimeric structure with D2 h symmetry. The reaction of hydride 4 with carbon dioxide and N, N′-diisopropylcarbodiimide gave formato ( 5) and formamidinato ( 7) derivatives as a result of the insertion of the heterocumulene into both ZnH bonds. Reaction with Ph2CO gave the diphenylmethoxy compound 6. Hydride 4 shows catalytic activity in the hydrosilylation of 1,1-diphenylethylene and methanolysis of silanes. [ABSTRACT FROM AUTHOR]

The construction of physical or chemical adsorbents for CO2 capture and sequestration (CCS) is a vital technology in the interim period on the way towards a sustainable low-carbon future. The search for efficient materials to satisfy the increasing demand for CCS has become extremely important. , including porous silica, porous carbons, and newly developed metal-organic frameworks and porous organic polymers, possessing regular and well-defined porous geometry and having a high surface area and pore volume, have been widely studied for separations on laboratory scale. On account of the dipole-quadrupole interactions between the polarizable CO2 molecule and the accessible nitrogen site, the investigations have indicated that the incorporation of accessible nitrogen-donor groups into the pore walls of can improve the affinity to CO2 and increase the CO2 uptake capacity and selectivity. The CO2-adsorption process based on solid nitrogen-rich porous adsorbents does generally not require heating of a large amount of water (60-70 wt %) for regeneration, while such a heating approach cannot be avoided in the regeneration of amine-based solution absorption processes. Thus, nitrogen-rich porous adsorbents show good regeneration properties without sacrificing high separation efficiency. As such, nitrogen-rich as highly promising CO2 adsorbents have been broadly fabricated and intensively investigated. This Focus Review highlights recent significant advances in nitrogen-rich for CCS. [ABSTRACT FROM AUTHOR]

An efficient nickel(0)-catalyzed highly regio- and stereoselective hydrocarboxylation of homopropargylic alcohols with ZnEt2 in the presence of CO2 (1 atm, balloon) to synthesize α-alkylidene-γ-butyrolactones is described. The catalyst is highly active and can be applied for the synthesis of (optically active) mono- or bicyclic α-alkylidene-γ-butyrolactones with excellent regio- and stereoselectivity and good functional group tolerance. The potential of the reaction has been demonstrated in the first synthesis of (±)-heteroplexisolide E. [ABSTRACT FROM AUTHOR]