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Photocatalytic selective oxidation of aromatic alcohols to aldehydes under mild conditions is of great significance for green and sustainable development, and design of photocatalysts with high efficiency is an interesting topic. Herein, we present a new conjugated microporous polymer photocatalyst named NiFe-CMP, composed of Ni-porphyrin and Fe-bipyridyl units, for efficient photocatalytic oxidation of aromatic alcohols. The porous structure of NiFe-CMP provides numerous absorption sites and exposes catalytically active centres, enhancing the reaction kinetics. Experimental and theoretical analyses indicate that the incorporation of Fe and Ni dual-metal sites not only enhances the dissociation of excitons into free charge carriers by regulating the electronic structures, but also reduces the reaction energy barrier for the formation of *O2 intermediates, thus promoting the massive production of ˙O2− active species. Impressively, NiFe-CMP manifests excellent catalytic performance, achieving a 96.2% conversion rate for the oxidation of benzyl alcohol to benzaldehyde under 4 hours of visible light radiation, over approximately 17 times higher than that of the pristine CMP. Besides, NiFe-CMP exhibits high recyclability and displays an excellent adaptability towards various aromatic alcohols. This work further advances the rational design of efficient photocatalysts for selective aromatic alcohol oxidation. [ABSTRACT FROM AUTHOR]

Metal oxide catalysts' performance depends on their crystal structure, including the surface arrangement and coordination of metal cations and oxygen anions on the exposed facets. Here, we fabricated Co3O4 nanocrystals (NCs) with predominantly exposed (110), (111), (112), and (114) facets in the shapes of nanorod (Co-R), hexagonal nanoplate (Co-H), nanolaminar (Co-L), and nanoparticle (Co-P), respectively. The Co3O4 NC with exposed (114) high-index facet exhibits the highest 5-hydroxymethylfurfural (HMF) electrocatalytic activity, while the Co3O4 NC with exposed (112) shows the lowest activity. Both density functional theory (DFT) calculations and experiments reveal that the primary factor impacting the catalytic performance of Co3O4 NCs is the difference in HMF adsorption energy on various crystal facets. By doping Cr into Co3O4 (114), we tuned the adsorption energy of HMF to an optimal level, thereby achieving the best catalytic performance. Based on this, the adsorption behavior of other aldehyde–alcohol organic small molecules was also evaluated, and the linear relationship between adsorption strength and catalytic activity was confirmed. This work demonstrates that adjusting the exposed crystal facets of Co3O4 can alter the adsorption and catalytic capabilities of aldehyde–alcohol organic small molecules. It also provides explicit knowledge that could improve our understanding of facet-dependent reactions for other metal oxide catalysts. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) and deep eutectic solvents (DESs) are regarded as two types of novel solvents with high tunability, which exist in the liquid state in a wide temperature range. The sustainability of ILs and DESs enable their wide utilization as solvents, absorbents, electrolytes, surfactants, catalysts, lubricants and photosensitizers. Additionally, the stability of ILs and DESs is necessary for their application in industry. However, not all ILs and DESs are sufficiently stable. Herein, we present a comprehensive and systematic review on the thermal, chemical, electrochemical, radiolytic and biological stability of ILs and DESs. This can provide a guide for the better design of ILs and DESs with higher stability for industrial applications. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are well-known as novel solvents due to their unique properties, which are indispensable for the development of green chemistry in the future. CoCl2·6H2O and NiCl2·6H2O-based DESs, which could be called magnetic DESs (MDESs) for short in view of their responsive behavior to an external magnetic field, have been widely used in many industrial applications, such as biomass treatment, electrolytes, and material preparation. For better application and full-scale development of these MDESs in various fields, eleven MDESs were prepared in this work by using CoCl2·6H2O and NiCl2·6H2O as hydrogen bond acceptors (HBAs) with alcohols, carboxylic acids and amides as hydrogen bond donors (HBDs), respectively. The intermolecular interactions between the components of MDESs were characterized via FTIR, 1H NMR and DSC analysis. In addition, physicochemical properties including density, viscosity, conductivity, ionicity, pH values, surface tension, thermostability and solvatochromic parameters were investigated. All MDESs exhibit acid characteristics and have good conductivity comparable with ionic liquids (ILs) and other DESs used for electrolytes. The results show that stronger H-bonding networks in Ni-based MDESs make them have higher density, viscosity, polarity and surface tension values than Co-based MDESs. Moreover, all prepared MDESs possess a good conductivity behavior which could be comparable to that of common organic solvents and ILs. According to this work, we could better comprehend the behavior of Co/Ni-based MDESs and choose the appropriate one for particular applications. [ABSTRACT FROM AUTHOR]

The concept of CO2 switchable deep eutectic solvents (DESs) was proposed and a series of CO2 switchable imidazole-based deep eutectic solvents (DESs) was designed. The CO2 switch mechanism was investigated and the system was used for easy emulsion separation of olive oil from DESs. The benign CO2 switchable DESs have great potential applications in dissolution and easy separation. [ABSTRACT FROM AUTHOR]

We for the first time have found that PEG-based DESs could volatilize at room temperature and atmospheric pressure. The mass loss from long-term evaporation of PEG-based DESs at 298.15 K for 1000 min could reach as high as 30.5% mass loss, ca. 6 times that of short-term evaporation (5.1% mass loss). Generally, the vaporization enthalpy of PEG-based DESs is found to lie between that of common organic solvents and that of ionic liquids, while some PEG-based DESs could be more volatile than common organic solvents. The evaporation of PEG-based DESs could be ascribed to their volatile constituents; however, the evaporation rate of each constituent is found to be very different. This is the first discovery of the higher volatility of PEG-based DESs at room temperature and atmospheric pressure. [ABSTRACT FROM AUTHOR]

A Rose bengal-functionalized porous organic polymer (RB-POP) was prepared with a specific surface area of up to 562 m2 g−1. In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, RB-POP supported Ag(0) nanoparticles exhibited excellent performance for catalyzing cyclization of propargyl alcohols with CO2 at 30 °C, achieving a TOF of 5000 h−1, the highest value among the reported ones. [ABSTRACT FROM AUTHOR]

The CO2-involved synthesis of chemicals is of great significance from the green and sustainable chemistry viewpoint. Herein, we report a non-noble metal catalytic system composed of CoF2, CsF and P(CH2CH2PPh2)3 (denoted as PP3) for the synthesis of N-containing heterocycles from ortho-substituted anilines and CO2/H2. Mechanism investigation indicates that [Co(PP3)H(CO2)]+ is a catalytically active intermediate under working conditions; and CsF plays important roles in activating ortho-substituted anilines via hydrogen bond interactions, thus promoting the formation of the final products. This catalytic system is highly efficient, and allows a wide scope of ortho-substituted anilines, together with excellent functional group tolerance, affording various N-containing heterocycles in good to excellent yields. [ABSTRACT FROM AUTHOR]

The CO2-involved synthesis of chemicals is of great significance from a green and sustainable point of view. Herein, we present an efficient Co-based catalytic system composed of a commercially available Co salt, the tetradentate phosphine ligand P-(CH2CH2PPh2)3, and a base, denoted as [Co]/PP3/base, for the synthesis of formamides via the formylation of amines with CO2/H2. It was indicated that the selectivity of products (i.e., formamide or methylamine) could be tuned to some extent via changing the solvent and the base. Using ethanol as the solvent, the Co(ClO4)2·6H2O/PP3/K2CO3 system showed high activity for the production of formamides, affording product yields of 82–95%, together with its broad substrate scope. Exploration of the reaction mechanism indicated that formamide was formed with HCOOH as the intermediate, while the methylamine byproduct was produced with HCHO as the intermediate via the hydrogenolysis of dialkylaminomethane. [ABSTRACT FROM AUTHOR]

A mesoporous imine-functionalized organic polymer (Imine-POP) was prepared based on the reaction of an aryl ammonium salt with an aromatic aldehyde in water without any catalyst and template. The Pd coordinated Imine-POP exhibited high catalytic activity for the N-formylation of amines with CO2/H2 at 100 °C, affording a series of formamides in high yields. [ABSTRACT FROM AUTHOR]

The synthesis of chemicals from biomass-derived compounds is an interesting and challenging topic. In this work, using the lignin-derived 2-phenoxyacetophenones as the feedstock we present a novel approach for the synthesis of benzanilides via the reaction of 2-phenoxyacetophenones with anilines catalyzed by CuCl2 in DMSO at 120 °C under an air atmosphere. This approach has wide scope for 2-phenoxyacetophenones and anilines, and various benzanilides accompanied by the corresponding phenols could be obtained in high yields via changing the 2-phenoxyacetophenones and anilines. The reaction mechanism study indicated that the oxidative cleavage of the C–C bond in 2-phenoxyacetophenones and the formation of a C–N bond occurred simultaneously in the reaction process, resulting in the formation of benzanilides together with phenols. [ABSTRACT FROM AUTHOR]

A metal-free and highly efficient catalytic system involving a task-specific ionic liquid, [P4444][p-2-O], and a pyrene-based conjugated polymer was developed for direct CO2 capture from air and its further photoreduction to CO under visible light irradiation, affording a CO production rate of 47.37 μmol g−1 h−1 with a selectivity of 98.3%. [ABSTRACT FROM AUTHOR]

Herein the reductive amination/cyclization of levulinic acid using phenylsilane was presented to selectively produce pyrrolidones versus pyrrolidines under mild conditions by switching the catalyst from AlCl3 to RuCl3. Using AlCl3 as the catalyst, pyrrolidones were solely obtained at room temperature, while RuCl3 as the catalyst selectively afforded pyrrolidines in high yields at 45 °C. [ABSTRACT FROM AUTHOR]

Mesoporous Tröger's base-functionalized polymers (Meso-TBPs) were prepared using a sulfonic acid group functionalized ionic liquid/H2O system, with surface areas up to 431 m2 g−1 and pore sizes of 3–15 nm. Ir(ii) coordinated Meso-TBPs exhibited extraordinary catalytic performance in the N-methylation of amines using methanol. [ABSTRACT FROM AUTHOR]

Uniform N-doped carbon nanotubes were obtained for the first time via a morphology-preserving thermal transformation of organic polymer nanotubes without any additional templates. These carbon nanotubes acted as a superior metal-free carbon catalyst for C–H arylation of benzene, reductive hydrogen atom transfer and oxidation reactions. [ABSTRACT FROM AUTHOR]

Polyureas derived from CO2 and diamines were effective for C–H arylation of benzene in the presence of t-BuOK, producing biaryl products with various substituents in high yields up to 97%. Dual-activation of K+ and t-BuO−, and π,π-stacking interaction between the substrate and the polymer backbone may account for the superior activity. [ABSTRACT FROM AUTHOR]

The efficient extraction of 5-hydroxymethylfurfural (HMF) from the conversion products of glucose in an ionic liquid has been achieved via charging compressed CO2 into the mixtures. The targeted and tunable extraction of HMF could be realized because of the insolubility of glucose and the tunable solubility of HMF in compressed CO2. [ABSTRACT FROM AUTHOR]

A Rose bengal-functionalized porous organic polymer (RB-POP) was prepared with a specific surface area of up to 562 m2 g−1. In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, RB-POP supported Ag(0) nanoparticles exhibited excellent performance for catalyzing cyclization of propargyl alcohols with CO2 at 30 °C, achieving a TOF of 5000 h−1, the highest value among the reported ones. [ABSTRACT FROM AUTHOR]

The CO2-involved synthesis of chemicals is of great significance from the green and sustainable chemistry viewpoint. Herein, we report a non-noble metal catalytic system composed of CoF2, CsF and P(CH2CH2PPh2)3 (denoted as PP3) for the synthesis of N-containing heterocycles from ortho-substituted anilines and CO2/H2. Mechanism investigation indicates that [Co(PP3)H(CO2)]+ is a catalytically active intermediate under working conditions; and CsF plays important roles in activating ortho-substituted anilines via hydrogen bond interactions, thus promoting the formation of the final products. This catalytic system is highly efficient, and allows a wide scope of ortho-substituted anilines, together with excellent functional group tolerance, affording various N-containing heterocycles in good to excellent yields. [ABSTRACT FROM AUTHOR]

The concept of CO2 switchable deep eutectic solvents (DESs) was proposed and a series of CO2 switchable imidazole-based deep eutectic solvents (DESs) was designed. The CO2 switch mechanism was investigated and the system was used for easy emulsion separation of olive oil from DESs. The benign CO2 switchable DESs have great potential applications in dissolution and easy separation.

A Rose bengal-functionalized porous organic polymer (RB-POP) was prepared with a specific surface area of up to 562 m 2 g -1 . In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, RB-POP supported Ag(0) nanoparticles exhibited excellent performance for catalyzing cyclization of propargyl alcohols with CO 2 at 30 °C, achieving a TOF of 5000 h -1 , the highest value among the reported ones.

A mesoporous imine-functionalized organic polymer (Imine-POP) was prepared based on the reaction of an aryl ammonium salt with an aromatic aldehyde in water without any catalyst and template. The Pd coordinated Imine-POP exhibited high catalytic activity for the N-formylation of amines with CO2/H2 at 100 °C, affording a series of formamides in high yields.

Mesoporous Tröger's base-functionalized polymers (Meso-TBPs) were prepared using a sulfonic acid group functionalized ionic liquid/H 2 O system, with surface areas up to 431 m 2 g -1 and pore sizes of 3-15 nm. Ir(ii) coordinated Meso-TBPs exhibited extraordinary catalytic performance in the N-methylation of amines using methanol.