Two in one: aluminum porphyrin-based porous organic polymers containing symmetrical quaternary phosphonium salts for catalytic conversion of CO2 into cyclic carbonates

Based on the double activation models of epoxides, the design and synthesis of ionic porous organic polymers (iPOPs) is considered to be very attractive and promising but has remained a great challenge in recent decades owing to electrostatic interactions between charged groups. In this contribution, we developed a two-in-one strategy to fabricate metalloporphyrin-based iPOPs with unique nanostructures (named AlPor-QP@POP), which are composed of aluminum porphyrin units and three-dimensional quaternary phosphonium salts that work synergistically in the cycloaddition of CO2 with epoxides under mild conditions. The high symmetry of two monomers allows them to possess similar reactivity ratios and thus endows AlPor-QP@POP with densely located active sites, a large surface area and good CO2 capture capacity. More importantly, bifunctional AlPor-QP@POP has enormous potential to produce cyclic carbonates with simulated flue gas under ambient conditions. Moreover, AlPor-QP@POP can be readily recycled and efficiently reused more than ten times without an obvious decrease in catalytic activity. Finally, kinetic investigations and a comparative study have been conducted to understand the possible mechanism of CO2 catalytic cycloaddition.

Cooperative catalysis of Cu/2,2,6,6-tetramethyl-1-piperidine-N-oxyl nanocatalysts supported by ultraviolet light-responsive polyimides

Azobenzene-containing polyimides were used as supports to immobilize pyrene-containing Cu/2,2,6,6-tetramethyl-1-piperidine-N-oxyl catalytic systems with UV-regulated cooperative behaviors.

Phosphorus containing porous organic polymers: synthetic techniques and applications in organic synthesis and catalysis

The phosphorus-containing porous organic polymer is a trending material for the synthesis of heterogeneous catalysts. Decades of investigations have established phosphines as versatile ligands in homogeneous catalysis. Recently, phosphine-based heterogeneous catalysts were synthesized to exploit the same electronic properties while leveraging extra stability and reusability. In the last few decades, the catalysts were applied in diverse organic transformations, including hydroformylation, hydrogenation, C-C, C-N and C-X coupling, hydrosilylation, oxidative-carbonylation reactions, and so on. However, even though these polymers possess a multifunctional character, they face multiple synthetic issues in controlling the pore size, increasing the surface area, and creating a single type of active site. This review summarizes the developments in this field over the last few decades, highlighting the current limitation and future scope.

Phosphonium-Based Porous Ionic Polymer with Hydroxyl Groups: A Bifunctional and Robust Catalyst for Cycloaddition of CO2 into Cyclic Carbonates

The integration of synergic hydrogen bond donors and nucleophilic anions that facilitates the ring-opening of epoxide is an effective way to develop an active catalyst for the cycloaddition of CO₂ with epoxides. In this work, a new heterogeneous catalyst for the cycloaddition of epoxides and CO₂ into cyclic carbonates based on dual hydroxyls-functionalized polymeric phosphonium bromide (PQPBr-2OH) was presented. Physicochemical characterizations suggested that PQPBr-2OH possessed large surface area, hierarchical pore structure, functional hydroxyl groups, and high density of active sites. Consequently, it behaved as an efficient, recyclable, and metal-free catalyst for the additive and solvent free cycloaddition of epoxides with CO₂. Comparing the activity of PQPBr-2OH with that of the reference catalysts based on mono and non-hydroxyl functionalized polymeric phosphonium bromides suggested that hydroxyl functionalities in PQPBr-2OH showed a critical promotion effect on its catalytic activity for CO₂ conversion. Moreover, PQPBr-2OH proved to be quite robust and recyclable. It could be reused at least ten times with only a slight decrease of its initial activity.

Two-in-one: construction of hydroxyl and imidazolium-bifunctionalized ionic networks in one-pot toward synergistic catalytic CO2 fixation

Two-in-one hydroxyl-incorporated imidazolium ionic network was constructed in one-pot quaternization for enhancing synergistic catalytic conversion of CO₂ under mild conditions.

Facile synthesis of crystalline viologen-based porous ionic polymers with hydrogen-bonded water for efficient catalytic CO2 fixation under ambient conditions

In this work, we report a series of crystalline viologen-based porous ionic polymers (denoted VIP-X, X = Cl or Br), that have in situ formed dicationic viologens paired with halogen anions and intrinsic hydrogen-bonded water molecules, towards metal-free heterogeneous catalytic conversion of carbon dioxide (CO₂) under mild conditions. The targeted VIP-X materials were facilely constructed via the Menshutkin reaction of 4,4′-bipyridine with 4,4′-bis(bromomethyl)biphenyl (BCBMP) or 4,4′-bis(chloromethyl)biphenyl (BBMBP) monomers. Their crystalline and porous structures, morphological features and chemical structures and compositions were fully characterized by various advanced techniques. The optimal catalyst VIP-Br afforded a high yield of 99% in the synthesis of cyclic carbonate by CO₂ cycloaddition with epichlorohydrin under atmospheric pressure (1 bar) and a low temperature (40 °C), while other various epoxides could be also converted into cyclic carbonates under mild conditions. Moreover, the catalyst VIP-Br could be separated easily and reused with good stability. The remarkable catalytic performance could be attributed to the synergistic effect of the enriched Br⁻ anions and available hydrogen bond donors –OH groups coming from H-bonded water molecules.

Viologen-based porous ionic polymers with halogen anions and hydrogen-bonded water were constructed for efficient catalytic CO₂ fixation under mild conditions.

Exploration of advanced porous organic polymers as a platform for biomimetic catalysis and molecular recognition

This Feature article summarizes our progress in the design of biomimetic POPs for catalysis and molecular recognition with enhanced performance.

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.