Pillar[5]arene-Based Co(III)-Loaded Covalent Organic Polymer for Efficient CO₂ Cycloaddition under Mild Conditions

Abstract

Generating promising materials for the conversion of CO2 to valuable industrial products under mild conditions is important for both ameliorating the greenhouse effect and sustainable development. Pillar[5]arene-incorporated materials have recently emerged as building frameworks to construct versatile functional polymeric materials. Herein, we demonstrate that highly efficient fixation of CO2 to cyclic carbonates can be achieved by employing a novel pillar[5]arene-based Co(III)-loaded covalent organic polymer (COP) as a heterogeneous catalyst (Co(III)–P5COP). The catalyst was created first by condensation of bromo-functionalized pillar[5]arene and a Schiff-base derivative (BHPD–OH) to afford the pillar[5]arene-based COP (P5COP), followed by loading Co(III) to prepare the target material bearing abundant salen–Co(III) sites. Results of catalysis with various substrates reveal excellent catalytic performance for CO2 cycloaddition with the conversion and selectivity of cyclic carbonate reaching up to 96 and 99%, respectively, under mild conditions of 30 °C and 1 atm CO2. Moreover, Co(III)–P5COP exhibits general applicability to other bulky epoxides. The polymeric pillar[5]arene-based catalysts could be easily recovered and reused without marked loss in their activity. Therefore, the marriage of Co(III)–salen and the pillar[5]arene platform constitutes a feasible approach to offering easily accessible and macrocycle-based new materials for the conversion of CO2 to valuable products.

Ionic Porous Organic Polymer Loaded with Zn(II) Ions for Efficient Cycloaddition of CO2 and Epoxides to Cyclic Carbonate

“…In addition, according to the Clausius–Clapeyron equation, the isosteric adsorption heat ( Q st ) of Zn-HUT4 for CO 2 was calculated (Figure f). Zn-HUT4 had high Q st value (36.1 kJ/mol) at low loading, which could be attributed to the effective capture of CO 2 by the rich polar groups containing N and O atoms on the HUT4 skeleton. − …”

“…In addition, we studied the catalytic performance of the catalyst under ambient conditions (Table 2, Entry 20). Owing to the mild reaction conditions, we used 5 mL of PO, 300 mg of Zn-HUT4 (0.414 mmol Zn), and 528 mg (1.62 mmol) of TBAB at 25 °C and 1 bar of CO 2 for 48 h. It was found that the conversion of PO was only 25.7%, the selectivity of PC was only 67.1%, and the remaining 32.9% of the product was polycarbonate without polyether segments (Figure S10), indicating that the catalytic activity of Zn-HUT4 under ambient conditions was not satisfactory, 30,36,38 so we did not further study it. In order to study the recyclability of the Zn-HUT4 catalyst, five cycles of catalytic experiments were carried out (Figure 4).…”

Photothermal Synergistic Catalysis over Defective Zn3In2S6 for CO2 Fixation

“…), which seriously have threatened the survival of human beings. Consequently, the capture and utilization of CO 2 has received unprecedented attention in recent years. , Among them, CO 2 cycloaddition reaction holds great promise because of its 100% atomic utilization efficiency and subsequent highly valued cyclic carbonate products. − However, nowadays, industrial routes mainly rely on the traditional TBAB, KI, and other halogen anion nucleophilic reagent homogeneous catalysts, which suffer from low conversion, harsh reaction conditions, and expensive equipment investment . Part of novel catalytic technology based on ionic liquid-based multifunctional homogeneous catalysts is still confronted with high reaction pressure, unsatisfied catalytic efficiency, and homogeneous separation problem. − As a result, developing highly efficient heterogeneous catalysts that can work under mild conditions holds great promise for technological upgrading of CO 2 cycloaddition.…”

“…Consequently, the capture and utilization of CO 2 has received unprecedented attention in recent years. 1,2 Among them, CO 2 cycloaddition reaction holds great promise because of its 100% atomic utilization efficiency and subsequent highly valued cyclic carbonate products. 3−5 However, nowadays, industrial routes mainly rely on the traditional TBAB, KI, and other halogen anion nucleophilic reagent homogeneous catalysts, 6 which suffer from low conversion, harsh reaction conditions, and expensive equipment investment.…”

Palladium recovery from acidic solution with phenanthroline-based covalent organic polymers as adsorbents for efficient heterogeneous catalysis

“…Covalent organic polymers (COPs) are a kind of attractive materials holding great application potential in the fields of environmental remediation and molecular or metal ion sieving. 22,23 They are constructed from repeating designable building blocks, which endows them with high structural modularity and abundant functionality. Furthermore, most COPs exhibit excellent hydrolytic stability even under highly acidic conditions because they are connected totally by stable covalent bonds.…”