Porous, fluorescent, covalent triazine-based frameworks via room-temperature and microwave-assisted synthesis

Sulfur-based hyper cross-linked polymers

The possibilities offered by sulphur-based chemistry to produce 3D-polymers based on a tetrakis(phenyl)methane core have been exploited: eight HCPs were generated by oxidation, nucleophilic substitution or thia-Michael additions.

Mannitol-based acetal-linked porous organic polymers for selective capture of carbon dioxide over methane

Synthesis of mannitol-based acetal-linked porous organic polymers with considerable CO₂/CH₄ selectivity is reported.

Azo-bridged covalent porphyrinic polymers (Azo-CPPs): synthesis and CO2 capture properties

“N₂-phobic” azo and porhpyrinic groups leading to high CO₂/N₂ selectivity at high temperature.

Microporous carbonaceous adsorbents for CO2separation via selective adsorption

This article reviews recently developed microporous carbonaceous adsorbents including inorganic carbons and organic polymers for CO₂separationviaselective adsorption.

Creating extra pores in microporous carbon via a template strategy for a remarkable enhancement of ambient-pressure CO2uptake

The creation of extra pores by removal of the silicon template in a porous carbon material derived from carbonizing silicon-containing POP has afforded a remarkable enhancement of ambient-pressure CO₂uptake capacity.

A novel 3D covalent organic framework membrane grown on a porous α-Al2O3 substrate under solvothermal conditions

A compact and uniform 3D COF-320 membrane with a layer thickness of ∼4 μm was grown on a porous α-Al₂O₃ ceramic substrate.

Modelling analysis of the structure and porosity of covalent triazine-based frameworks

We assess structure directing effects and potential origins of structural order and formulate basic rules relating building block structure to porosity properties.

Facile synthesis of porous organic polymers bifunctionalized with azo and porphyrin groups

Azo and porphyrin bifunctionalized porous polymer networks (azo-PPors) with BET surface areas up to 750 m² g⁻¹ were synthesized via a catalyst-free direct coupling of tetra(4-nitrophenyl)porphyrin and aryl amine monomers.

A uniformly porous 2D CN (1 : 1) network predicted by first-principles calculations

Using the first-principles simulations, we predicate a 2D CN (1 : 1) network and explore its potential applications in electronics, gas separation, and catalysis.

Amide functionalized microporous organic polymer (Am-MOP) for selective CO₂ sorption and catalysis

We report the design and synthesis of an amide functionalized microporous organic polymer (Am-MOP) prepared from trimesic acid and p-phenylenediamine using thionyl chloride as a reagent. Polar amide (-CONH-) functional groups act as a linking unit between the node and spacer and constitute the pore wall of the continuous polymeric network. The strong covalent bonds between the building blocks (trimesic acid and p-phenylenediamine) through amide bond linkages provide high thermal and chemical stability to Am-MOP. The presence of a highly polar pore surface allows selective CO2 uptake at 195 K over other gases such as N2, Ar, and O2. The CO2 molecule interacts with amide functional groups via Lewis acid-base type interactions as demonstrated through DFT calculations. Furthermore, for the first time Am-MOP with basic functional groups has been exploited for the Knoevenagel condensation reaction between aldehydes and active methylene compounds. Availability of a large number of catalytic sites per volume and confined microporosity gives enhanced catalytic efficiency and high selectivity for small substrate molecules.

Conjugated microporous polymers: design, synthesis and application

Conjugated microporous polymers (CMPs) are a class of organic porous polymers that combine π-conjugated skeletons with permanent nanopores, in sharp contrast to other porous materials that are not π-conjugated and with conventional conjugated polymers that are nonporous. As an emerging material platform, CMPs offer a high flexibility for the molecular design of conjugated skeletons and nanopores. Various chemical reactions, building blocks and synthetic methods have been developed and a broad variety of CMPs with different structures and specific properties have been synthesized, driving the rapid growth of the field. CMPs are unique in that they allow the complementary utilization of π-conjugated skeletons and nanopores for functional exploration; they have shown great potential for challenging energy and environmental issues, as exemplified by their excellent performance in gas adsorption, heterogeneous catalysis, light emitting, light harvesting and electrical energy storage. This review describes the molecular design principles of CMPs, advancements in synthetic and structural studies and the frontiers of functional exploration and potential applications.

Synthesis and gas adsorption properties of tetra-armed microporous organic polymer networks based on triphenylamine

Two novel tetra-armed microporous organic polymers have been designed and synthesized via a nickel-catalyzed Yamamoto-type Ullmann cross-coupling reaction or Suzuki cross-coupling polycondensation. These polymers are stable in various solvents, including concentrated hydrochloric acid, and are thermally stable. The homocoupled polymer YPTPA shows much higher Brunauer-Emmet-Teller-specific surface area up to 1557 m(2) g(-1) than the copolymer SPTPA (544 m(2) g(-1)), and a high CO2 uptake ability of 3.03 mmol g(-1) (1.13 bar/273 K) with a CO2 /N2 sorption selectivity of 17.3:1. Both polymers show high isosteric heats of CO2 adsorption (22.7-26.5 kJ mol(-1)) because the incorporation of nitrogen atoms into the skeleton of microporous organic polymers enhances the interaction between the pore wall and the CO2 molecules. The values are higher than those of the porous aromatic frameworks, which contain neither additional polar functional groups nor nitrogen atoms, and are rather close to those of previously reported microporous organic polymers containing the nitrogen atoms on the pore wall. These data show that these materials would be potential candidates for applications in post-combustion CO2 capture and sequestration technology.

Nitrogen-containing microporous conjugated polymers via carbazole-based oxidative coupling polymerization: preparation, porosity, and gas uptake

Facile preparation of microporous conjugated polycarbazoles via carbazole-based oxidative coupling polymerization is reported. The process to form the polymer network has cost-effective advantages such as using a cheap catalyst, mild reaction conditions, and requiring a single monomer. Because no other functional groups such as halo groups, boric acid, and alkyne are required for coupling polymerization, properties derived from monomers are likely to be fully retained and structures of final polymers are easier to characterize. A series of microporous conjugated polycarbazoles (CPOP-2-7) with permanent porosity are synthesized using versatile carbazolyl-bearing 2D and 3D conjugated core structures with non-planar rigid conformation as building units. The Brunauer-Emmett-Teller specific surface area values for these porous materials vary between 510 and 1430 m(2) g(-1) . The dominant pore sizes of the polymers based on the different building blocks are located between 0.59 and 0.66 nm. Gas (H2 and CO2 ) adsorption isotherms show that CPOP-7 exhibits the best uptake capacity for hydrogen (1.51 wt% at 1.0 bar and 77 K) and carbon dioxide (13.2 wt% at 1.0 bar and 273 K) among the obtained polymers. Furthermore, its high CH4 /N2 and CO2 /N2 adsorption selectivity gives polymer CPOP-7 potential application in gas separation.

An electroactive porous network from covalent metal–dithiolene links

Direct reaction between a hexathiol and PtCl₂ leads to the formation of a covalent metal–organic framework (CMOF) featuring substantial porosity, redox activity and ion exchange capability.

Metallosalen-based microporous organic polymers: synthesis and carbon dioxide uptake

Three metallosalen-based microporous organic polymers were designed and synthesized. New materials display excellent porosity and good capacities for store and separation of carbon dioxide at 273 K and 1 bar.

Conjugated microporous polytriphenylamine networks

Conjugated microporous polytriphenylamine networks with surface areas of 530 m² g⁻¹ were synthesized via Buchwald–Hartwig coupling, resulting in high CO₂ uptake (up to 6.5 wt%) and CO₂–N₂ selectivity (75) at 1 bar and 303 K.

Restricted access: on the nature of adsorption/desorption hysteresis in amorphous, microporous polymeric materials

The phenomenon of low-pressure adsorption/desorption hysteresis, which is commonly observed in microporous polymers, is investigated by detailed gas adsorption studies. Diffusional limitations by pore blocking effects, which arise as a consequence of the micropore morphology and connectivity, are discussed as the origin of the hysteresis rather than swelling effects, which have been suggested previously. Micropores with narrow openings, which cannot be filled easily, are expected to be present next to open pores. Those pores are termed restricted-access pores and are only filled in the course of the adsorption process as a consequence of the increasing solvation pressure exhibited from already filled micropores. As a consequence of the results presented here, it is suggested to use the desorption branch in addition to the adsorption branch for the extraction of the porosity characteristics, such as specific surface area, pore volume, and pore size distribution. The magnitude of the low-pressure hysteresis might hence give an idea of the micropore connectivity, which is important information for potential applications.

Shedding Light on Structure-Property Relationships for Conjugated Microporous Polymers: The Importance of Rings and Strain

The photophysical properties of insoluble porous pyrene networks, which are central to their function, differ strongly from those of analogous soluble linear and branched polymers and dendrimers. This can be rationalized by the presence of strained closed rings in the networks. A combined experimental and computational approach was used to obtain atomic scale insight into the structure of amorphous conjugated microporous polymers. The optical absorption and fluorescence spectra of a series of pyrene-based materials were compared with theoretical time-dependent density functional theory predictions for model clusters. Comparison of computation and experiment sheds light on the probable structural chromophores in the various materials.

Dynamic nuclear polarization NMR spectroscopy allows high-throughput characterization of microporous organic polymers

Dynamic nuclear polarization (DNP) solid-state NMR was used to obtain natural abundance (13)C and (15)N CP MAS NMR spectra of microporous organic polymers with excellent signal-to-noise ratio, allowing for unprecedented details in the molecular structure to be determined for these complex polymer networks. Sensitivity enhancements larger than 10 were obtained with bis-nitroxide radical at 14.1 T and low temperature (∼105 K). This DNP MAS NMR approach allows efficient, high-throughput characterization of libraries of porous polymers prepared by combinatorial chemistry methods.

Efficient CO2 Capture by a 3D Porous Polymer Derived from Tröger's Base

A 3D Tröger's-base-derived microporous organic polymer with a high surface area and good thermal stability was facilely synthesized from a one-pot metal-free polymerization reaction between dimethoxymethane and triaminotriptycene. The obtained material displays excellent CO₂ uptake abilities as well as good adsorption selectivity for CO₂ over N₂. The CO₂ storage can reach up to 4.05 mmol g^-1 (17.8 wt %) and 2.57 mmol g^-1 (11.3 wt %) at 273 K and 298 K, respectively. Moreover, the high selectivity of the polymer toward CO₂ over N₂ (50.6, 298 K) makes it a promising material for potential application in CO₂ separation from flue gas.

On-surface synthesis of single-layered two-dimensional covalent organic frameworks via solid-vapor interface reactions

Surface covalent organic frameworks (SCOFs), featured by atomic thick sheet with covalently bonded organic building units, are promised to possess unique properties associated with reduced dimensionality, well-defined in-plane structure, and tunable functionality. Although a great deal of effort has been made to obtain SCOFs with different linkages and building blocks via both "top-down" exfoliation and "bottom-up" surface synthesis approaches, the obtained SCOFs generally suffer a low crystallinity, which impedes the understanding of intrinsic properties of the materials. Herein, we demonstrate a self-limiting solid-vapor interface reaction strategy to fabricate highly ordered SCOFs. The coupling reaction is tailored to take place at the solid-vapor interface by introducing one precursor via vaporization to the surface preloaded with the other precursor. Following this strategy, highly ordered honeycomb SCOFs with imine linkage are obtained. The controlled formation of SCOFs in our study shows the possibility of a rational design and synthesis of SCOFs with desired functionality.

Microporous Polymer Networks (MPNs) Made in Metal-Free Regimes: Systematic Optimization of a Synthetic Protocol toward N-Arylcarbazole-Based MPNs

Acidic self-condensation of 2,7-bis(N-carbazolyl)-9-fluorenone 1 produces microporous polymer networks (MPNs) with high Brunauer-Emmett-Teller (BET) surface areas of up to 2250 m²/g and hydrogen storage capacities of up to 1.7% (at 1 bar) in a fully metal-free condensation regime.

From a supramolecular tetranitrile to a porous covalent triazine-based framework with high gas uptake capacities

Transformation of tetra(4-cyanophenyl)ethylene under Lewis acidic (ZnCl2) conditions at 400 °C leads to the formation of a porous covalent triazine-based organic framework (CTF) with a high surface area (2235 m(2) g(-1)), high CO2 and CH4 uptakes and the highest hydrogen uptake for a CTF material (1.86 wt% at 77 K, 1 bar).

Conjugated organic framework with three-dimensionally ordered stable structure and delocalized π clouds

Covalent organic frameworks are a class of crystalline organic porous materials that can utilize π-π-stacking interactions as a driving force for the crystallization of polygonal sheets to form layered frameworks and ordered pores. However, typical examples are chemically unstable and lack intrasheet π-conjugation, thereby significantly limiting their applications. Here we report a chemically stable, electronically conjugated organic framework with topologically designed wire frameworks and open nanochannels, in which the π conjugation-spans the two-dimensional sheets. Our framework permits inborn periodic ordering of conjugated chains in all three dimensions and exhibits a striking combination of properties: chemical stability, extended π-delocalization, ability to host guest molecules and hole mobility. We show that the π-conjugated organic framework is useful for high on-off ratio photoswitches and photovoltaic cells. Therefore, this strategy may constitute a step towards realizing ordered semiconducting porous materials for innovations based on two-dimensionally extended π systems.