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While aiming at sustainable organic synthesis, over the last decade particular attention has been focused on two modern fields, C–H bond activation, and visible-light-induced photocatalysis. Couplings through C–H bond activation involve the use of non-prefunctionalized substrates that are directly converted into more complex molecules, without the need of a previous functionalization, thus considerably reduce waste generation and a number of synthetic steps. In parallel, transformations involving photoredox catalysis promote radical reactions in the absence of radical initiators. They are conducted under particularly mild conditions while using the visible light as a cheap and economic energy source. In this way, these strategies follow the requirements of environment-friendly chemistry. Regarding intrinsic advantages as well as the complementary mode of action of the two catalytic transformations previously introduced, their merging in a synergistic dual catalytic system is extremely appealing. In that perspective, the scope of this review aims to present innovative reactions combining C–H activation and visible-light induced photocatalysis.

In contrast to the stereocontrol of the stereocenter at the allyl unit, the asymmetric induction of prochiral nucleophiles remains a challenge in Pd-catalyzed asymmetric allylic substitutions due to the remote distance between the chiral catalyst and the stereocenter established at prochiral nucleophile. Much effort has been devoted to solving this challenge through the elaborate design of chiral ligands. Recently, synergistic catalysis has gained increasing attention owing to its potential advantages over the traditional single palladium catalysis, such as improvement of reactivity and selectivity. This strategy, including bimetallic catalysis and Pd/organocatalysis, not only broadens the scope of prochiral nucleophiles, but also provides a simple and unified method for the stereocontrol of prochiral nucleophiles. This review summarizes the brief history and advances in this field.

Oil is the “blood” and economic lifeblood of modern industry, but traditional light crude oil has been over-consumed, and it has been difficult to meet human demand for energy, so the exploitation of heavy oil is particularly important. In this paper, an oil-soluble catalyst was synthesized to catalyze the pyrolysis reaction of heavy oil in collaboration with reservoir minerals, so as to achieve efficient viscosity reduction of heavy oil and reduce production costs. The experimental results showed that Zn(II)O + K had the best synergistic viscosity reduction effect after the aquathermolysis of No. 1 oil sample under the reaction conditions of 180 °C, 4 h, 30% of water, and 0.2% of catalyst, respectively, and the viscosity reduction rate was 61.74%. Under the catalysis of the isopropanol system, the viscosity reduction rate was increased to 91.22%. A series of characterizations such as freezing point, thermogravimetric analysis, DSC analysis, component analysis, gas chromatography, wax crystal morphology analysis, and GC-MS analysis of aqueous organic matter were carried out on heavy oil after reaction by different reaction systems, and it could be verified that the viscosity of heavy oil was reduced. Finally, through the study of the reaction mechanism of the model compound, combined with the aqueous phase analysis, it can be clearly found that the depolymerization between macromolecules, the breaking of heteroatom chains, hydrogenation, ring opening, and other effects mainly occur during the reaction, thereby weakening the van der Waals force and hydrogen bond of the recombinant interval, inhibiting the formation of grid structure in heavy oil and effectively reducing the viscosity of heavy oil.

We report the development of a new class of multifunctional chiral guanidine/Pd(0) catalyst system for 1,4-addition/arylation tandem reaction. A variety of tetra-substituted allenes were readily accessible from three-component “one-pot” transformations of acyclic or cyclic 2-activated 1,3-enynes, malonates and halobenzenes under mild reaction conditions. High levels of yield and enantioselectivity were achieved in the construction of stereogenic center and axis using readily available acyclic guanidine-amides. The mechanistic studies suggest that the guanidine/Pd(0) collaboration has obvious synergism to both base-dominated conjugate addition, and Pd(0)-dominated Heck-type reaction.

To study the synergistic catalysis of an ex situ catalyst and in situ clay in the aquathermolysis of heavy oil, in this paper, a series of bentonite-supported catechol-metal complexes were prepared, and the catalytic viscosity reduction performance in the aquathermolysis of heavy oil was investigated. Under the optimized conditions, the viscosity can be reduced by 73%, and the pour point can be lowered by 15.0 °C at most, showing the synergistic catalysis of the ex situ catalyst and in situ clay in this aquathermolytic reaction. Thermogravimetry, physical adsorption-desorption, and scanning electron microscopy were conducted to characterize the thermal stability and microstructure of the ex situ catalyst. The components of the heavy oil before and after the reaction were fully characterized. Six model compounds were used to simulate the aquathermolysis reaction process. In order to study the mechanism of viscosity reduction after the catalytic aquathermolysis reaction, the compounds were analyzed by GC-MS. It is believed that these results will be beneficial in the future for related research in this field.

Two heterobimetallic Mo,M’ complexes (M’ = IrIII, RhIII) were synthesized and fully characterized. Their catalytic activity in homogeneous carbon dioxide hydrogenation to formate was studied. A pronounced synergistic effect between the two metals was found, most notably between Mo and Ir, leading to a fourfold increase in activity compared with a binary mixture of the two monometallic counterparts. This synergism can be attributed to spatial proximity of the two metals rather than electronic interactions. To further understand the nature of this interaction, the mechanism of the CO2 hydrogenation to formate by a monometallic IrIII catalyst was studied using computational and spectroscopic methods. The resting state of the reaction was found to be the metal-base adduct, whereas the rate-determining step is the inner-sphere hydride transfer to CO2. Based on these findings, the synergism in the heterobimetallic complex is beneficial in this key step, most likely by further activating the CO2.

Inspired by multimetallic assemblies and their role in enzyme catalysis, chemists have developed a plethora of heterobimetallic complexes for application in homogeneous catalysis. Starting with small heterobimetallic complexes with σ-donating and π-accepting ligands, such as N-heterocyclic carbene and carbonyl ligands, more and more complex systems have been developed over the past two decades. These systems can show a significant increase in catalytic activity compared with their monometallic counterparts. This increase can be attributed to new reaction pathways enabled by the presence of a second metal center in the active catalyst. This review focuses on mechanistic aspects of heterobimetallic complexes in homogeneous catalysis. Depending on the type of interaction of the second metal with the substrates, heterobimetallic complexes can be subdivided into four classes. Each of these classes is illustrated with multiple examples, showcasing the versatility of both, the types of interactions possible, and the reactions accessible.

Covalent organic frameworks (COFs)-based nanoreactors have attracted broad interest in many fields due to their void-confinement effects. However, the inherent drawback of conventional nanoreactors is the lack of internal active sites, which limits their widespread utilization. Herein, we report the construction of hierarchical COF (EB-TFP) nanoreactor with pre-synthesized polyoxometalates (POM, [PV 2 W 10 O 40 ] 5− (PV 2 W 10 )) clusters encapsulated inside of COF (POM@COF). PV 2 W 10 @EB-TFP anchors nucleophilic-group (Br − ions) and PV 2 W 10 anion cluster within the COF framework via electrostatic interactions, which not only simplifies the reaction system but also enhances catalytic efficiency. The reaction performance of the PV 2 W 10 @EB-TFP nanoreactor can be tuned to achieve excellent catalytic activity in CO 2 cycloaddition reaction (CCR) for ∼ 97.63% conversion and ∼ 100% selectivity under visible light irradiation. A mechanistic study based on density functional theory (DFT) calculations and in-situ characterization was also carried out. In summary, we have reported a method for achieving the uniform dispersion of POM single clusters into COF nanoreactor, demonstrating the potential of POM@COF nanoreactor for synergistic photothermal catalytic CO 2 cycloaddition.

Mimicking the photosynthesis of green plants to combine water oxidation with CO2 reduction is of great significance for solving energy and environmental crises. In this context, a trinuclear nickel complex, [NiII3(paoH)6(PhPO3)2]·2ClO4 (1), with a novel structure has been constructed with PhPO32− (phenylphosphonate) and paoH (2-pyridine formaldehyde oxime) ligands and possesses a reflection symmetry with a mirror plane revealed by single-crystal X-ray diffraction. Bulk electrocatalysis demonstrates that complex 1 can homogeneously catalyze water oxidation and CO2 reduction simultaneously. It can catalyze water oxidation at a near-neutral condition of pH = 7.45 with a high TOF of 12.2 s−1, and the Faraday efficiency is as high as 95%. Meanwhile, it also exhibits high electrocatalytic activity for CO2 reduction towards CO with a TOF of 7.84 s−1 in DMF solution. The excellent electrocatalytic performance of the water oxidation and CO2 reduction of complex 1 could be attributed to the two unique µ3-PhPO32− bridges as the crucial factor for stabilizing the trinuclear molecule as well as the proton transformation during the catalytic process, while the oxime groups modulate the electronic structure of the metal centers via π back-bonding. Therefore, apart from the cooperation effect of the three Ni centers for catalysis, simultaneously, the two kinds of ligands in complex 1 can also synergistically coordinate the central metal, thereby significantly promoting its catalytic performance. Complex 1 represents the first nickel molecular electrocatalyst for both water oxidation and CO2 reduction. The findings in this work open an avenue for designing efficient molecular electrocatalysts with peculiar ligands.

Rationally constructing atom‐precise active sites is highly important to promote their catalytic performance but still challenging. Herein, this work designs and constructs ZSM‐5 supported Cu and Ag dual single atoms as a proof‐of‐concept catalyst (Ag 1 −Cu 1 /ZSM‐5 hetero‐SAC (single‐atom catalyst)) to boost direct oxidation of methane (DOM) by H 2 O 2 . The Ag 1 −Cu 1 /ZSM‐5 hetero‐SAC synthesized via a modified co‐adsorption strategy yields a methanol productivity of 20,115 µmol g cat −1 with 81% selectivity at 70 °C within 30 min, which surpasses most of the state‐of‐the‐art noble metal catalysts. The characterization results prove that the synergistic interaction between silver and copper facilitates the formation of highly reactive surface hydroxyl species to activate the C−H bond as well as the activity, selectivity, and stability of DOM compared with SACs, which is the key to the enhanced catalytic performance. This work believes the atomic‐level design strategy on dual‐single‐atom active sites should pave the way to designing advanced catalysts for methane conversion.