Heterogeneous catalytic conversion of CO2 and epoxides to cyclic carbonates over multifunctional tri-s-triazine terminal-linked ionic liquids

Halogen Bonding in the Decoration of Secondary Coordination Sphere of Zinc(II) and Cadmium(II) Complexes: Catalytic Application in Cycloaddition Reaction of CO2 with Epoxides

Three new zinc(II) complexes [Zn(H2L3)2(H2O)3] (Zn2), [Zn(H3L2a)(H2O)3]n (Zn3) (H3L2a = 2,4-diiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl)isophthalate) and [Zn(HL4)(DMF)(H2O)]n (Zn4) were synthesized by the reaction of Zn(II) salts with 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl) isophthalic acid (H3L3), 2,4,6-triiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl) isophthalic acid (H5L2) (in the presence of NH2OH·HCl) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)-2,4,6-triiodoisophthalic acid (H3L4), respectively. According to the X-ray structural analysis, the intramolecular resonance-assisted hydrogen bond ring remains intact, with N···O distances of 2.562(5) and 2.573(5) Å in Zn2, 2.603(6) Å in Zn3, and 2.563(8) Å in Zn4. In the crystal packing of Zn3, the cooperation of I···O and I···I types of halogen bonds between tectons leads to a one-dimensional supramolecular polymer, while I···O interactions aggregate 1D chains of coordination polymer Zn4. These new complexes (Zn2, Zn3, and Zn4) and known [Zn(H3L1)(H2O)2]n (Zn1) (H3L1 = 5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene) hydrazineyl)isophthalate), {[Zn(H3L1)(H2O)3]·3H2O}n (Zn5), [Cd(H3L1)(H2O)2]n (Cd1), {[Cd(HL3)(H2O)2(DMF)]·H2O}n (Cd2), [Cd(H3L3)]n (Cd-3), {[Cd2(μ-H2O)2(μ-H2L4)2(H2L4)2]·2H2O}n (Cd4), and {[Cd(H3L1)(H2O)3]·4H2O}n (Cd5) were tested as catalysts in the cycloaddition reaction of CO2 with epoxides in the presence of tetrabutylammonium halides as the cocatalyst. The halogen-bonded catalyst Zn4 is the most efficient one in the presence of tetrabutylammonium bromide by affording a high yield (85-99%) of cyclic carbonates under solvent-free conditions after 48 h at 40 bar and 80 °C.

Efficient imidazolium ionic liquid as a tri-functional robust catalyst for chemical fixation of CO2 into cyclic carbonates

The recent increase in CO₂ levels has had an extensive impact on the environment; hence an effective catalyst for chemical CO₂ fixation into value-added products is demanded. This work demonstrates a simple approach towards the chemical fixation of CO₂ to cyclic carbonates without solvent, metal and additives using one-pot synthesized tri-functional-imidazolium bromide ionic liquid. Herein, synthesized tri-functional-imidazolium-based ionic liquids, namely 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium bromide ([VIMEtOH][Br] (24 and 72 h)), 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium hydroxyl ([VIMEtOH][OH]) and poly 3-(2-hydroxyethyl)-1-vinyl-1H-imidazole-3-ium bromide (poly [VIMEtOH][Br]), were used for the comprehensive investigation of chemical fixation of CO₂ into cyclic carbonates and their physiochemical properties. In case of [VIMEtOH][Br] ionic liquid, it displayed time-dependent synthesis dissolution in the reaction system. This study found that [VIMEtOH][Br]-72 ionic liquid is not dissolved in the reaction system. The effect on the catalytic efficiency of the presence of functional groups in ionic liquids such as N-vinyl (-CC-N), acidic proton of imidazolium (-C (2)-H) and hydroxyl (-OH) along with bromide anion and the reaction conditions are systematically investigated. For CO₂ fixation, 99.6% conversion of propylene oxide with an excellent selectivity of propylene carbonate (≥99%) over [VIMEtOH][Br]-72 catalyst (at 120 °C, 2 MPa, 2 h) was observed without co-catalyst, metal and solvent. Also, it demonstrated an excellent wide substrates scope of epoxide and all reactions were performed on gram-scalable, which are potential prospects for industrial use.

Metal phosphonates as heterogeneous catalysts for highly efficient chemical fixation of CO2 under mild conditions

Two new compounds with novel structures were prepared, one of which displays excellent catalytic activity to transform CO2 gas to cyclic carbonates under mild conditions and free of solvent.

Coupling of CO2 with Epoxides by Bifunctional Periodic Mesoporous Organosilica with Ionic Liquid Frameworks under Solvent, Additive and Metal-Free Conditions

Despite huge catalytic systems which have already been introduced to the direct coupling of CO2 with the epoxide to obtain the corresponding cyclic carbonate, the design of new systems which...

Aminoethylimidazole ionic liquid-grafted MIL-101-NH2 heterogeneous catalyst for the conversion of CO2 and epoxide without solvent and cocatalyst

An aminoethylimidazole IL-functionalized MIL-101-NHIM-NH₂ catalyst efficiently catalyzes the cycloaddition reaction of CO₂ and epoxide without solvent and cocatalyst, owing to the synergistic effects of Cr, –NH₂ and Br⁻ active sites.

A dual-functional urea-linked conjugated porous polymer anchoring silver nanoparticles for highly efficient CO2 conversion under mild conditions

A dual-functional urea-linked conjugated porous polymer (UCPP) assembled by enol-imine with ordered unit arrays that act as potential anchoring sites in the networks was fabricated, and was further applied as a support for Ag nanoparticles by the coordinate interaction between them. The UCPP not only can well confine the Ag particle size and facilitate high dispersion, but also can afford special CO₂-philic moieties to enhance the adsorption properties. The resulting Ag@UCPP as a heterogeneous catalyst exhibited excellent activity for the carboxylative cyclization of propargyl alcohols with CO₂ under mild conditions, together with good recyclability, which is probably attributed to the synergistic effect of the UCPP on the adsorption and activation of CO₂ and the immobilization of Ag nanoparticles. This work affords possible opportunities for the design and synthesis of a heterogeneous catalyst toward CO₂ conversion.

Ionic-Liquid-Modified Click-Based Porous Organic Polymers for Controlling Capture and Catalytic Conversion of CO2

Capture and catalytic conversion of CO₂ into value-added chemicals is a promising and sustainable approach to relieve global warming and the energy crisis. Nitrogen-rich porous organic polymers (POPs) are promising materials for CO₂ capture and separation, but their application in the additive-free catalytic conversion of CO₂ into cyclic carbonates is still a challenge. Herein, a nitrogen-rich click-based POP (CPP) was developed for the cycloaddition reaction of CO₂ with epoxides in the absence of metal, solvents, and additives. The introduction of imidazolium-based ionic liquids on the CPP host backbone could modulate the porosity, CO₂ adsorption/desorption, CO₂ selectivity over N₂ , and catalytic activity in the chemical transformation. A tentative catalytic pathway was proposed to account for the superior catalytic activity of the catalytic systems, in which the incorporated ionic liquid and porous properties of CPP synergistically contributed to the catalytic reaction. This study provides a platform to understand the cooperative effects of porous properties and nucleophilic anions on the cycloaddition reaction of CO₂ with epoxides.

Integration of metalloporphyrin into cationic covalent triazine frameworks for the synergistically enhanced chemical fixation of CO2

Cobalt porphyrin as a Lewis acidic site was integrated into imidazolium-functionalized porous cationic covalent triazine frameworks for the cooperatively enhanced catalysis CO₂ cycloaddition to produce cyclic carbonates.

Immobilized BiCl3@Bi@g-C3N4 on one-dimensional multi-channel carbon fibers as heterogeneous catalyst for efficient CO2 cycloaddition reaction

A novel heterogeneous catalyst (BBCNC), where the Bi, BiCl₃ and g-C₃N₄ were deposited on one-dimensional multi-channel carbon fibers (CNFs), was developed and characterized.

Novel Cobalt Complex as an Efficient Catalyst for Converting CO2 into Cyclic Carbonates under Mild Conditions

Based on the ligand H2dpPzda (1), a novel cobalt complex [Co(H2dpPzda)(NCS)2]·CH3OH(2) has been synthesized and characterized. The Complex 2 exhibited excellent catalytic performance for converting CO2 into cyclic carbonates under mild conditions. For propylene oxide (PO) and CO2 synthesis of propylene carbonate (PC), the catalytic system showed a remarkable TOF as high as 29,200 h−1. The catalytic system also showed broad substrate scope of epoxide. Additionally, the catalyst could be recycled to maintain the integrity of the structure and remained equal to the level of its catalytic activity even after seven catalytic rounds. Additionally, a possible catalytic mechanism was proposed due to the high catalytic activity which might be owing to the synergism of Lewis acidic metal centers and N group.

Metal β-diketonate complexes as highly efficient catalysts for chemical fixation of CO2 into cyclic carbonates under mild conditions

The potential of metal β-diketonate complexes for the catalysis of the chemical fixation of CO₂ into cyclic carbonates at 1 atm CO₂ and near room temperature was demonstrated. Their potential for the capture and simultaneous conversion of CO₂ in a dilute CO₂ stream was also determined. The catalysts were easily synthesized and commercially available. Therefore, this CO₂ transformation was less energy- and material-consuming, which made this reaction closer to true "green" chemistry.

Recent Advances in the Chemical Fixation of Carbon Dioxide: A Green Route to Carbonylated Heterocycle Synthesis

Carbon dioxide produced by human activities is one of the main contributions responsible for the greenhouse effect, which is modifying the Earth’s climate. Therefore, post-combustion CO2 capture and its conversion into high value-added chemicals are integral parts of today’s green industry. On the other hand, carbon dioxide is a ubiquitous, cheap, abundant, non-toxic, non-flammable and renewable C1 source. Among CO2 usages, this review aims to summarize and discuss the advances in the reaction of CO2, in the synthesis of cyclic carbonates, carbamates, and ureas appeared in the literature since 2017.

Efficient Conversion of CO2 via Grafting Urea Group into a [Cu2(COO)4]-Based Metal-Organic Framework with Hierarchical Porosity

The assembly of mixed [1,1';3',1'']terphenyl-4,5',4''-tricarboxylic acid (H₃TPTC) and [1,1'-biphenyl]-4,4'-dicarboxylic acid (H₂BPDC), 2,2'-diamino-[1,1'-biphenyl]-4,4'-dicarboxylic acid (H₂BPDC-NH₂), or 6-oxo-6,7-dihydro-5H-dibenzo[ d, f][1,3]diazepine-3,9-dicarboxylic acid (H₂BPDC-Urea) with Cu²⁺ ion generated the corresponding copper-paddlewheel-based metal-organic framework (MOF) [Cu₅(TPTC)₃(BPDC)_0.5(H₂O)₅] (1), [Cu₅(TPTC)₃(BPDC-NH₂)_0.5(H₂O)₅] (1-NH₂), or [Cu₅(TPTC)₃(BPDC-Urea)_0.5(H₂O)₅] (1-Urea). They are isostructural with hierarchical porosity, consisting of zero-dimensional cage (19.2 Å × 18.9 Å) and one-dimensional pillar channel (29.7 Å × 15.1 Å) in a manner of face sharing. Platon analyses revealed the porous volume ratios are 80.2%, 80.0%, and 77.8% for 1, 1-NH₂, and for 1-Urea, respectively. Thermogravimetric measurements suggested 53, 51, and 48 wt % guest molecules in 1, 1-NH₂, and 1-Urea, respectively. 1-NH₂ and 1-Urea were precisely functionalized via the introduction of amino and urea functional groups into the pillar channels. The constructed MOF 1-Urea, incorporating both exposed copper active sites and accessible urea functional groups to substrates, presents high efficiency on catalytic CO₂ cycloaddition with propene oxide to produce cyclic carbonate in the yield of 98% with a TOF value of 136 h^-1 at 1 atm and room temperature. This synergic effect provides a new strategy for designing high-efficient catalysts for CO₂ chemical conversion under ambient conditions.

A tri-functional metal–organic framework heterogeneous catalyst for efficient conversion of CO2 under mild and co-catalyst free conditions

A novel tri-functional MOF catalyst was achieved by PSM method. Because of the synergistic effect of Lewis acid, Brønsted acid and Br⁻ anion, MIL-IMAc-Br⁻ displayed an efficient catalytic performance for CO₂ conversion.

Nitrogen-doped metal-free carbon catalysts for (electro)chemical CO2 conversion and valorisation

This review focuses on the recent developments made in the fabrication of N-doped carbon materials for enhanced CO₂ conversion and electrochemical reduction into high-value-added products.