Charged Covalent Triazine Frameworks for CO2 Capture and Conversion

Highly Efficient Catalytic Cyclic Carbonate Formation by Pyridyl Salicylimines

Cyclic carbonates as industrial commodities offer a viable nonredox carbon dioxide fixation, and suitable heterogeneous catalysts are vital for their widespread implementation. Here, we report a highly efficient heterogeneous catalyst for CO₂ addition to epoxides based on a newly identified active catalytic pocket consisting of pyridine, imine, and phenol moieties. The polymeric, metal-free catalyst derived from this active site converts less-reactive styrene oxide under atmospheric pressure in quantitative yield and selectivity to the corresponding carbonate. The catalyst does not need additives, solvents, metals, or co-catalysts, can be reused at least 10 cycles without the loss of activity, and scaled up easily to a kilogram scale. Density functional theory calculations reveal that the nucleophilicity of pyridine base gets stronger due to the conjugated imines and H-bonding from phenol accelerates the reaction forward by stabilizing the intermediate.

Boosting lithium storage in covalent organic framework via activation of 14-electron redox chemistry

Conjugated polymeric molecules have been heralded as promising electrode materials for the next-generation energy-storage technologies owing to their chemical flexibility at the molecular level, environmental benefit, and cost advantage. However, before any practical implementation takes place, the low capacity, poor structural stability, and sluggish ion/electron diffusion kinetics remain the obstacles that have to be overcome. Here, we report the synthesis of a few-layered two-dimensional covalent organic framework trapped by carbon nanotubes as the anode of lithium-ion batteries. Remarkably, upon activation, this organic electrode delivers a large reversible capacity of 1536 mAh g⁻¹ and can sustain 500 cycles at 100 mA g⁻¹. Aided by theoretical calculations and electrochemical probing of the electrochemical behavior at different stages of cycling, the storage mechanism is revealed to be governed by 14-electron redox chemistry for a covalent organic framework monomer with one lithium ion per C=N group and six lithium ions per benzene ring. This work may pave the way to the development of high-capacity electrodes for organic rechargeable batteries.

Conjugated polymeric molecules are promising electrode materials for batteries. Here the authors show a two-dimensional few-layered covalent organic framework that delivers a large reversible capacity of more than 1500 mAh g⁻¹ with the storage mechanism governed by 14-electron redox chemistry.

An imidazolium-functionalized mesoporous cationic metal–organic framework for cooperative CO2 fixation into cyclic carbonate

A mesoporous cationic Cr-based metal–organic framework (MOF), FJI-C10, has been obtained and exhibited excellent performances in chemical fixation of CO₂ into cyclic carbonates under co-catalyst free and mild conditions.

Exceptionally stable Rh-based molecular catalyst heterogenized on a cationically charged covalent triazine framework support for efficient methanol carbonylation

Direct carbonylation of methanol into methyl acetate and acetic acid using Rh-based heterogeneous catalysts is of great interest due to their effective levels of activity and stability.

Constructing POSS and viologen-linked porous cationic frameworks induced by the Zincke reaction for efficient CO2 capture and conversion

POSS and viologen-linked porous cationic frameworks were constructed via the Zincke reaction towards efficient CO₂ capture and conversion under ambient conditions.

Charged porous organic frameworks bearing heteroatoms with enhanced isosteric enthalpies of gas adsorption

Charged porous organic frameworks containing heteroatoms were synthesized via a Yamamoto-type Ullmann coupling reaction using potassium tetrakis(4-bromopyrazolyl)borate and tetrakis(4-chlorophenyl)phosphonium bromide as monomers. For the first time, a monomer containing boron atoms was successfully homocoupled to obtain a 3D charged porous organic framework. The heteroatoms and charges in the porous organic frameworks help to increase the interaction between the frameworks and the gases. Therefore the charged porous organic frameworks bearing heteroatoms synthesized in the present study exhibit high isosteric enthalpies of gas adsorption which surpass those of many other porous organic materials.

Charged porous organic frameworks bearing heteroatoms which synthesized via Yamamoto-type Ullmann coupling reaction exhibit high isosteric enthalpies of gas adsorption.

Imidazolium- and Triazine-Based Porous Organic Polymers for Heterogeneous Catalytic Conversion of CO2 into Cyclic Carbonates

CO₂ adsorption and concomitant catalytic conversion into useful chemicals are promising approaches to alleviate the energy crisis and effects of global warming. This is highly desirable for developing new types of heterogeneous catalytic materials containing CO₂ -philic groups and catalytic active sites for CO₂ chemical transformation. Here, we present an imidazolium- and triazine-based porous organic polymer with counter chloride anion (IT-POP-1). The porosity and CO₂ affinity of IT-POP-1 may be modulated at the molecular level through a facile anion-exchange strategy. Compared with the post-modified polymers with iodide and hexafluorophosphate anions, IT-POP-1 possesses the highest surface area and the best CO₂ uptake capacity with excellent adsorption selectivity over N₂ . The roles of the task-specific components such as triazine, imidazolium, hydroxyl, and counter anions in CO₂ absorption and catalytic performance were illustrated. IT-POP-1 exhibits the highest catalytic activity and excellent recyclability in solvent- and additive-free cycloaddition reaction of CO₂ with epoxides.

CO2 Complexes with Five-Membered Heterocycles: Structure, Topology, and Spectroscopic Characterization

In a first step toward the rational design of macrocyclic structures optimized for CO₂ capture, we systematically explored the potential of 30 five-membered aromatic heterocycles to establish coordinating complexes with this pollutant. The interactions between the two moieties were studied in several orientations, and the obtained complexes were analyzed in terms of electron density and vibrational fingerprint. The former is an aid to provide an in-depth knowledge of the interaction, whereas the latter should help to select structural motifs that have not only good complexation properties but also diagnostic spectroscopic signals.

Effective Acetylene/Ethylene Separation at Ambient Conditions by a Pigment-Based Covalent-Triazine Framework

A novel covalent-triazine framework (CTF-PO71) is designed and prepared from an organic pigment molecule for high-performance gas separation. The functional sites with different electrostatic potentials on the pore surface of CTF-PO71 demonstrate a strong interaction between C₂ H₂ and CTF-PO71 to achieve preferential adsorption of C₂ H₂ over C₂ H₄ , thus enabling effective capture of a trace amount of C₂ H₂ from the gas mixture. This is the first organic porous polymer that is capable of separating C₂ H₂ and C₂ H₄ . The commercial availability and the low cost of the pigment as well as the high stability of the resultant framework endow CTF-PO71 with a significant potential for practical applications.

The phosphinoboration of carbodiimides, isocyanates, isothiocyanates and CO2

The transition metal-free addition of phosphinoboronate ester Ph₂PBpin (pin = 1,2-O₂C₂Me₄) to heterocumulenes including carbodiimides, isocyanates, isothiocyanates and carbon dioxide proceeds with remarkable selectivity to give products in high yield.