Functional materials: from hard to soft porous frameworks

Chemistry of Mesoporous Organosilica in Nanotechnology: Molecularly Organic-Inorganic Hybridization into Frameworks

Organic-inorganic hybrid materials aiming to combine the individual advantages of organic and inorganic components while overcoming their intrinsic drawbacks have shown great potential for future applications in broad fields. In particular, the integration of functional organic fragments into the framework of mesoporous silica to fabricate mesoporous organosilica materials has attracted great attention in the scientific community for decades. The development of such mesoporous organosilica materials has shifted from bulk materials to nanosized mesoporous organosilica nanoparticles (designated as MONs, in comparison with traditional mesoporous silica nanoparticles (MSNs)) and corresponding applications in nanoscience and nanotechnology. In this comprehensive review, the state-of-art progress of this important hybrid nanomaterial family is summarized, focusing on the structure/composition-performance relationship of MONs of well-defined morphology, nanostructure, and nanoparticulate dimension. The synthetic strategies and the corresponding mechanisms for the design and construction of MONs with varied morphologies, compositions, nanostructures, and functionalities are overviewed initially. Then, the following part specifically concentrates on their broad spectrum of applications in nanotechnology, mainly in nanomedicine, nanocatalysis, and nanofabrication. Finally, some critical issues, presenting challenges and the future development of MONs regarding the rational synthesis and applications in nanotechnology are summarized and discussed. It is highly expected that such a unique molecularly organic-inorganic nanohybrid family will find practical applications in nanotechnology, and promote the advances of this discipline regarding hybrid chemistry and materials.

Hybrid Amine-Functionalized Graphene Oxide as a Robust Bifunctional Catalyst for Atmospheric Pressure Fixation of Carbon Dioxide using Cyclic Carbonates

An environmentally-benign carbocatalyst based on amine-functionalized graphene oxide (AP-GO) was synthesized and characterized. This catalyst shows superior activity for the chemical fixation of CO2 into cyclic carbonates at the atmospheric pressure. The developed carbocatalyst exhibits superior activity owing to its large surface area with abundant hydrogen bonding donor (HBD) capability and the presence of well-defined amine functional groups. The presence of various HBD and amine functional groups on the graphene oxide (GO) surface yields a synergistic effect for the activation of starting materials. Additionally, this catalyst shows high catalytic activity to synthesize carbonates at 70 °C and at 1 MPa CO2 pressure. The developed AP-GO could be easily recovered and used repetitively in up to seven recycle runs with unchanged catalyst activity.

Facilely Fabricating Multifunctional N-Enriched Carbon

A new synthetic strategy, named "carbonization in limited space" and based on the specific interaction between eutectic salt and dual-ionic liquids (dual-ILs), is reported in this article. N-Containing dual-ILs (1,4-diethyl-1,4-diazaniabicyclo[2,2,2]octane imidazolide-4,5-dicyanoiazolide, [2C2DABCO](2+)[Im](-)[CN-Im](-)) were synthesized as new carbon-nitrogen precursors, while eutectic salt was chosen as a reuseable template in order to facilely fabricate the N-doped porous carbon with sheetlike morphology. Nitrogen can be directly and efficiently incorporated into the porous carbon, resulting in the materials with suitable N content, tunable pore structure, and controllable thickness of sheet as well as high surface area. They exhibited good performance as electrodes for supercapacitors, photocatalysts in degradation of methyl orange (MO) under visible light, and the sorbent to capture tobacco-specific N-nitrosamines (TSNAs) in solution, offering a new simplified but effective method to prepare versatile carbon material.

Catalytic properties of N-hydroxyphthalimide immobilized on a novel porous organic polymer in the oxidation of toluene by molecular oxygen

A novel porous organic polymer pSt was prepared based on silica gel and used for the immobilization of NHPI. The obtained heterogeneous catalyst could adsorb toluene and oxidize it to benzoic acid using a co-catalyst Co(OAc)₂ and molecular oxygen.

Recent developments in the catalytic hydrogenation of CO2 to formic acid/formate using heterogeneous catalysts

This review highlights the recent trends in the heterogeneous hydrogenation of CO₂ to formic acid/formate.

Microporous organic network@PET hybrid membranes: removal of minute organic pollutants dissolved in water

Microporous organic networks (MONs) were incorporated into a polyethylene terephthalate (PET) membrane. The resultant MON@PET hybrid membranes showed promising filtration towards aromatic pollutants dissolved in water.

A two-dimensional conjugated polymer framework with fully sp2-bonded carbon skeleton

2D conjugated COF based on olefin (CC) linkages has been readily synthesized using the Knoevenagel condensation reaction.

Covalent organic frameworks based on Schiff-base chemistry: synthesis, properties and potential applications

Covalent organic-frameworks (COFs) are an emerging class of porous and ordered materials formed by condensation reactions of organic molecules.

Amine post-functionalized POSS-based porous polymers exhibiting simultaneously enhanced porosity and carbon dioxide adsorption properties

We provide a possibility for post-synthetic amine functionalization of porous polymers exhibiting enhanced CO₂ capacity and selectivity without compromising the porosity.

Solid-state emissive cyanostilbene based conjugated microporous polymers via cost-effective Knoevenagel polycondensation

Solid-state emissive cyanostilbene-based conjugated porous polymers with different topological structure and photophysical properties were newly synthesized via cost-effective Knoevenagel polycondensation.

Direct arylation polymerization towards narrow bandgap conjugated microporous polymers with hierarchical porosity

Conjugated microporous polymers are synthesized via facile direct arylation polymerization, resulting in conjugated networks with hierarchical porosity and a narrow bandgap of 1.5 eV.

A supramolecular strategy based on molecular dipole moments for high-quality covalent organic frameworks

Attractive intermolecular interactions of building blocks with strong dipole moments result in a COF with high crystallinity and large surface area.

Observation of the wrapping mechanism in amine carbon dioxide molecular interactions on heterogeneous sorbents

CO₂ binds multiple amines if nearby, leading to higher heats of adsorption, a previously unknown observation.

Nanoporous ionic organic networks: from synthesis to materials applications

This review highlights the recent progress made in the study of the synthesis of nanoporous ionic organic networks (NIONs) and their promising applications.

Functionalized hypercrosslinked polymers with knitted N-heterocyclic carbene–copper complexes as efficient and recyclable catalysts for organic transformations

An N-heterocyclic carbene–copper complex supported on hypercrosslinked polymers was synthesized and characterized by spectroscopic methods, displaying very good catalytic activity in many organic reactions.

A hydroxyl-functionalized microporous organic polymer for capture and catalytic conversion of CO2

A novel hydroxyl-functionalized microporous organic polymer (HF-MOP) exhibited good CO₂ capture performance and excellent catalytic activity in cycloaddition reaction.

Synthesis of triphenylphosphine-based microporous organic nanotube framework supported Pd catalysts with excellent catalytic activity

A novel synthesis of triphenylphosphine-based microporous organic nanotube frameworks (MONFs-PPh₃) as a platform for Pd catalyst (MONFs-PPh₃@Pd) is reported.

Phthalazinone structure-based covalent triazine frameworks and their gas adsorption and separation properties

In this work, new classes of phthalazinone-based covalent triazine frameworks (PHCTFs) were prepared by ionothermal synthesis from two full rigid dicyano building blocks with rigid, thermostable and asymmetric N-heterocycle-containing structures.

Monodispersed ultramicroporous semi-cycloaliphatic polyimides for the highly efficient adsorption of CO2, H2and organic vapors

Monodispersed ultramicroporous semi-cycloaliphatic polyimides (sPIs) were synthesizedviasolution polycondensation and possess high uptakes for CO₂, H₂, aromatic and aliphatic vapors, exhibiting potential in gas storage and the recovery of toxic organic vapors.

Electrospun nanofibers with both surface nanopores and internal interpenetrated nanochannels for oil absorption

We report novel polyoxymethylene nanofibers with both surface nanopores and internal interpenetrated channels. Their novel interesting structure makes them an ideal alternative for oil adsorption, oil/water separation or catalysis in the future.

Supramolecular organic network assembled from quadruple hydrogen-bonding motifs

A rigid triptycene derivative with three 2-ureido-4[1H]-pyrimidinone (UPy) terminals was employed to construct a supramolecular hydrogen-bonded organic polymer (HOP-1).

Enantioselective tandem reaction over a site-isolated bifunctional catalyst

An active site-isolated organoruthenium-/organopalladium-functionalized yolk–shell-structured mesoporous silica is developed and its application in the one-pot enantioselective tandem Sonogashira coupling–asymmetric transfer hydrogenation of haloacetophenones and arylacetylenes to various chiral conjugated alkynols is investigated.

Construction of bimodal silsesquioxane-based porous materials from triphenylphosphine or triphenylphosphine oxide and their size-selective absorption for dye molecules

Phosphorus-containing porous materials from octavinylsilsesquioxane possessed unique bimodal structure and exhibited an excellent size-selective absorption for dye molecules.

State-of-the-art catechol porphyrin COF catalyst for chemical fixation of carbon dioxide via cyclic carbonates and oxazolidinones

A highly porous, crystalline catechol porphyrin COF was synthesized and applied as an organocatalyst for the fixation of carbon dioxide to synthesize value-added chemicals such as cyclic carbonates and oxazolidinones under solvent and transition-metal-free conditions.

Narrow bandgap thienothiadiazole-based conjugated porous polymers: from facile direct arylation polymerization to tunable porosities and optoelectronic properties

Conjugated porous polymers with narrow bandgaps, tunable morphologies, porosities and optoelectronic properties are synthesized via facile direct arylation polymerization.

A robust and luminescent covalent organic framework as a highly sensitive and selective sensor for the detection of Cu2+ions

A highly crystalline and porous azine-linked covalent organic framework possesses excellent stability and luminescence properties with high quantum yield. It can serve as a promising luminescent probe for selectively sensing copper ions.

Ru coordinated with BINAP in knitting aryl network polymers for heterogeneous asymmetric hydrogenation of methyl acetoacetate

The aryl network polymers formed by Friedel–Crafts reaction with no-modified BINAP chiral ligand, and its application in asymmetric hydrogenation.

Tunable porosity of 3D-networks with germanium nodes

Eight hyper cross-linked polymers based on tetrakis(4-ethynylphenyl)germanium and tetrakis(4-ethynylphenyl)methane are presented.

Heptazine-Based Porous Framework for Selective CO2 Sorption and Organocatalytic Performances

A new heptazine-based polymer network (Cy-pip) with highly rich nitrogen sites has been synthesized via catalyst-free direct coupling of cyameluric chloride (Cy) and piperazine (Pip). Cy-pip exhibits large CO2 uptake capacity (103.4 mg/g, 9.4 wt %, 1 bar/273 K) with high selectivity (117) toward CO2 over N2. Furthermore, this framework with high Lewis basic nitrogen sites has also been exploited as heterogeneous catalyst for Knoevenagel reaction of aromatic and heterocyclic aldehydes with active methylene compounds. Moreover, the catalyst can recycle up to four times with only a minor loss of activity.

Creation of a new type of ion exchange material for rapid, high-capacity, reversible and selective ion exchange without swelling and entrainment

A new model for ion exchange materials has been proposed on the basis of ion exchange sites grafted to a porous organic polymer.

Ion-exchange materials, currently dominated by resins, are widely used in a plethora of areas. However, the drawbacks of conventional resins necessitate the creation of a new model of ion exchange materials that feature controllable swelling, easily accessible ion exchange sites, high ion exchange capacity, fast ion exchange kinetics, and high chemical stability as illustrated herein in the context of functionalizing a porous organic polymer (POP) with ion exchange groups. The advantages of POP-based ion exchange materials in comparison with conventional resins and other types of ion exchange materials have been highlighted through an evaluation of their performances in scavenging precious metals at trace concentrations, removal of nuclear waste model ions, and size-selective ion capture. Our work thereby provides a new perspective to develop ion functionalized POPs as a versatile type of ion exchange materials for various applications.

Metal-free and Scalable Synthesis of Porous Hyper-cross-linked Polymers: Towards Applications in Liquid-Phase Adsorption

A metal-free route for the synthesis of hyper-cross-linked polymers (HCP) based on Brønsted acids such as trifluoromethanesulfonic acid as well as H2 SO4 is reported. It is an improved method compared to conventional synthesis strategies that use stoichiometric amounts of metal-based Lewis acids such as FeCl3 . The resulting high-performance adsorbents exhibit a permanent porosity with high specific surface areas up to 1842 m(2)  g(-1) . Easy scalability of the HCP synthesis is proven on the multi-gram scale. All chemo-physical properties are preserved. Water-vapor adsorption shows that the resulting materials exhibit an even more pronounced hydrophobicity compared to the conventionally prepared materials. The reduced surface polarity enhances the selectivity in the liquid-phase adsorption of the biogenic platform chemical 5-hydroxymethylfurfural.

Polysulfide-Blocking Microporous Polymer Membrane Tailored for Hybrid Li-Sulfur Flow Batteries

Redox flow batteries (RFBs) present unique opportunities for multi-hour electrochemical energy storage (EES) at low cost. Too often, the barrier for implementing them in large-scale EES is the unfettered migration of redox active species across the membrane, which shortens battery life and reduces Coulombic efficiency. To advance RFBs for reliable EES, a new paradigm for controlling membrane transport selectivity is needed. We show here that size- and ion-selective transport can be achieved using membranes fabricated from polymers of intrinsic microporosity (PIMs). As a proof-of-concept demonstration, a first-generation PIM membrane dramatically reduced polysulfide crossover (and shuttling at the anode) in lithium-sulfur batteries, even when sulfur cathodes were prepared as flowable energy-dense fluids. The design of our membrane platform was informed by molecular dynamics simulations of the solvated structures of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) vs lithiated polysulfides (Li2Sx, where x = 8, 6, and 4) in glyme-based electrolytes of different oligomer length. These simulations suggested polymer films with pore dimensions less than 1.2-1.7 nm might incur the desired ion-selectivity. Indeed, the polysulfide blocking ability of the PIM-1 membrane (∼0.8 nm pores) was improved 500-fold over mesoporous Celgard separators (∼17 nm pores). As a result, significantly improved battery performance was demonstrated, even in the absence of LiNO3 anode-protecting additives.