Pd NP-loaded covalent organic framework for pH-switched Pickering emulsion catalytic dechlorination.

Quinoline carboxylic acid-linked and Pd nanoparticle (NP)-loaded COF nanospheres were constructed via a three-component one-pot Doebner reaction and post-synthetic metalation. The obtained Pd@DhaTAPB-COOH solid stabilizer can greatly promote the pH-switched recyclable Pickering interfacial dechlorination reaction, which sheds light on the bright future of smart Pickering emulsion catalysis.

Synthesis of covalent organic frameworks via Kabachnik-Fields reaction for water treatment.

Providing safe and clean domestic water for people is currently one of the greatest worldwide issues. In this context, heavy metal ions and pathogenic microbes are the two major factors in water pollution. The conventional water treatment methods, however, are generally high-energy and high-resource consumptive. Herein, we report, the first of its kind, the room-temperature synthesis of α-aminophosphonate-linked COFs via three-component one-pot in situ Kabachnik-Fields reaction (KF-3CR). Due to the coexistent bioactive α-aminophosphonate and photosensitive porphyrin, the obtained APCOF-1 exhibits highly efficient solar-powered bactericidal and heavy metal ion removal abilities, which allows it to be a promising COF-based multifunctional material for water treatment in an energy- and resource-saving way. Specifically, by incorporating APCOF-1 (up to 50 wt%) with eco-friendly and low-cost chitosan, an APCOF-1 @chitosan aerogel-based helical setup is fabricated via a facile templated freeze-drying approach and it can be a continuous flow-through water purifier model to achieve scaled-up water treatment through adsorptive removal of heavy metal ions and sunlight-driven sterilization. We believe that this research not only can significantly enrich the synthetic methodology of COFs, but also will hopefully bring COFs one step closer to the practical application.

Synthesis of Chiral Covalent Organic Frameworks via Asymmetric Organocatalysis for Heterogeneous Asymmetric Catalysis.

A general and efficient organocatalytic asymmetric polymerization approach for the synthesis of chiral covalent organic frameworks (CCOFs) has been developed. With a chiral 2-methylpyrrolidine catalyst, a series of tris(N-salicylideneamine)-derived ß-ketoenamine-CCOFs are directly constructed from prochiral aldehyde- and primary amine-monomers. The adopted aminocatalytic asymmetric Schiff-base condensation herein is performed under ambient conditions with clear green synthetic advantages over the conventional acid-catalysed solvothermal methods. The obtained ß-ketoenamine-CCOFs can be further metalated by a solid-state coordination approach, and the resulting CuII @CCOFs can highly promote an asymmetric A3 -coupling reaction. Specifically, a CuII @CCOF@chitosan aerogel was fabricated as a highly efficient fixed-bed model reactor for scaled-up catalysis. The concept of aminocatalytic asymmetric polymerization might open a new way for constructing the CCOFs via asymmetric organocatalysis.

Metalloporphyrin and Ionic Liquid-Functionalized Covalent Organic Frameworks for Catalytic CO2 Cycloaddition via Visible-Light-Induced Photothermal Conversion.

We report the construction of a porphyrin and imidazolium-ionic liquid (IL)-decorated and quinoline-linked covalent organic framework (COF, abbreviated as COF-P1-1) via a three-component one-pot Povarov reaction. After post-synthetic metallization of COF-P1-1 with Co(II) ions, the metallized COF-PI-2 is generated. COF-PI-2 is chemically stable and displays highly selective CO2 adsorption and good visible-light-induced photothermal conversion ability (ΔT = 26 °C). Furthermore, the coexistence of Co(II)-porphyrin and imidazolium-IL within COF-PI-2 has guaranteed its highly efficient activity for CO2 cycloaddition. Of note, the needed thermal energy for the reactions is derived from the photothermal conversion of the Co(II)-porphyrin COF upon visible-light irradiation. More importantly, the CO2 cycloaddition herein is a "window ledge" reaction, and it can proceed smoothly upon natural sunlight irradiation. In addition, a scaled-up CO2 cycloaddition can be readily achieved using a COF-PI-2@chitosan aerogel-based fixed-bed model reactor. Our research provides a new avenue for COF-based greenhouse gas disposal in an eco-friendly and energy- and source-saving way.

Core-Shell-Structured Covalent-Organic Framework as a Nanoagent for Single-Laser-Induced Phototherapy.

Imaging-guided phototherapy, including photothermal therapy and photodynamic therapy, has been emerging as a promising avenue for precision cancer treatment. However, the utilization of a single laser to induce combination phototherapy and multiple-model imaging remains a great challenge. Herein, we report, the first of its kind, a covalent-organic framework (COF)-based magnetic core-shell nanocomposite, Fe3O4@COF-DhaTph, that is used as a multifunctional nanoagent for cancer theranostics under single 660 nm NIR irradiation. Besides significant photothermal and photodynamic effects, it still permits triple-modal magnetic resonance/photoacoustic/near-infrared thermal (IR) imaging due to its unequaled magnetic and optical performance. We believe that the results obtained herein could obviously promote the application of COF-based multifunctional nanomaterials in cancer theranostics.

Synergistic Antibacterial and Anti-Inflammatory Effects of a Drug-Loaded Self-Standing Porphyrin-COF Membrane for Efficient Skin Wound Healing.

Chronic wound infections resulting from severe bacterial invasion have become a major medical threat worldwide. Herein, we report a large-area, homogeneous, and self-standing porphyrin-covalent organic framework (COF)-based membrane with encapsulated ibuprofen (IBU) via an in situ interfacial polymerization and impregnation approach. The obtained IBU@DhaTph-membrane exhibits highly effective antibacterial and anti-inflammatory effects via synergistic light-induced singlet oxygen (1 O2 ) generation and controllable IBU release, which is well supported by in vitro experiments. In addition, the IBU@DhaTph-membrane-based biocompatible "band-aid" type dressing is fabricated, and its excellent anti-infection and tissue remodeling activities are fully evidenced by in vivo chronic wound-healing experiments. This study may inspire and promote the fabrication of many more new types of COF-based multifunctional biomaterials for various skin injuries in clinical medicine.

Sulfonic Acid and Ionic Liquid Functionalized Covalent Organic Framework for Efficient Catalysis of the Biginelli Reaction.

A quinoline-linked and ionic liquid-decorated covalent organic framework was prepared by incorporation of a multicomponent Povarov reaction and postsynthetic modification. The imidazolium and sulfonic acid-decorated COF-IM-SO3H can be a highly efficient Brønsted acid catalyst to promote the Biginelli reaction under solvent-free conditions in a heterogeneous way. In addition, a scaled-up Biginelli reaction has been readily realized over a COF-IM-SO3H@chitosan aerogel-based cup reactor.

Computational prediction of a novel 1D InSeI nanochain with high stability and promising wide-bandgap properties.

Low-dimensional materials have aroused widespread interest for their novel and fascinating properties. Based on first-principles calculations, we predict the one-dimensional (1D) InSeI nanochains with van der Waals (vdW) interchain interactions, which could be exfoliated mechanically and kept at steady states at room temperature. Compared with bulk InSeI, the single nanochain InSeI has a larger direct bandgap of 3.15 eV. Its calculated carrier mobility is as high as 54.17 and 27.49 cm2 V-1 s-1 for holes and electrons, respectively, comparable with those of other 1D materials. In addition, a direct-to-indirect bandgap transition is implemented under a small applied strain (∼6%). More importantly, the nanochains are found to be promising candidates for optoelectronic devices since they possess a high absorption coefficient of ∼105 cm-1 in the ultraviolet region. The results thus pave a novel avenue for the applications of InSeI nanochains with excellent thermal stability in nanoelectronic and optoelectronic devices.

Pd NP-Loaded and Covalently Cross-Linked COF Membrane Microreactor for Aqueous CBs Dechlorination at Room Temperature.

We report an allyl-decorated and hydrazine-connected covalent organic framework (COF-AO, 1), which could support Pd nanoparticles (Pd NPs) to generate Pd@COF-AO, 2. The incorporation of 2 with thiol-functionalized polysiloxane (termed as PSI-SH) via thiol-ene click reaction provided the stand-alone and elastic membrane (3). The obtained COF-involved and Pd NP-loaded covalently linked membrane of 3 is robust, permanently porous, uniform, processable, and water permeable. Moreover, it can be used to construct highly efficient membrane-based microreactor for continuous-flow operation to catalyze chlorobenzenes (CBs) dechlorination in water at room temperature. The provided approach herein allows the processability and practical application of the powdered COF materials to be feasible.

Chemically Cross-Linked MOF Membrane Generated from Imidazolium-Based Ionic Liquid-Decorated UiO-66 Type NMOF and Its Application toward CO2 Separation and Conversion.

Carbon dioxide capture and transformation are of great importance to make cuts in greenhouse gas emissions. Nanometal-organic frameworks (NMOFs) could serve as ideal fillers for polymer membranes owing to their structural diversity and regulable microenvironment of the nanocage. Herein, a bifunctional, robust, and chemically cross-linked NMOF-based membrane was successfully constructed by the postsynthetic polymerization of imidazolium-based ionic liquid (IL)-decorated UiO-66 type nanoparticles (NPs) and the isocyanate-terminated polyurethane oligomer under mild conditions. The IL-modified MOF-polymer membranes exhibit a highly selective adsorption for CO2 over N2 and CH4. In addition, the obtained membrane can also be a highly active heterogeneous catalyst for CO2 transformation by cycloaddition with epoxide under an ambient pressure.

Smart pH-Responsive Polymer-Tethered and Pd NP-Loaded NMOF as the Pickering Interfacial Catalyst for One-Pot Cascade Biphasic Reaction.

A Pd nano particle (NP)-loaded and nano metal-organic framework (NMOF)-based Pickering emulsifier is reported. The poly[2-(diethylamino)ethyl methacrylate)] (PDEAEMA) chains were grafted onto UiO-66-type NPs via a postsynthetic approach to generate PDEAEMA-g-UiO-66 NMOF (termed as MOF-3). The Pd NPs-loaded Pd@MOF-3 was synthesized via solution impregnation. Stable toluene-in-water Pickering emulsion was prepared with emulsifier Pd@MOF-3. Notably, the obtained Pd@MOF-3 is pH-responsive, and it is able to trigger the emulsification (at neutral condition) and demulsification (at acidic condition) of toluene droplets. Furthermore, it can be a highly active interfacial catalyst to effectively promote one-pot Knoevenagel condensation-hydrogenation cascade reaction at ambient conditions. The pH-responsive property allowed it to be in situ separated and recycled by demulsifying via simply tuning the pH value at the end of the reaction. This smart Pickering emulsion catalytic system is robust, and it can be recycled at least five times without loss of its catalytic activity.

Bifunctional Imidazolium-Based Ionic Liquid Decorated UiO-67 Type MOF for Selective CO2 Adsorption and Catalytic Property for CO2 Cycloaddition with Epoxides.

A bifunctional robust and highly porous imidazolium-based ionic liquid decorated UiO-67 type MOF (UiO-67-IL, 1) was successfully constructed via solvothermal assembly of the imidazolium-based ligand and Zr(IV) ions. It exhibits a highly selective adsorption for CO2 over CH4 and N2. Furthermore, 1 herein can be used as a highly active heterogeneous catalyst for CO2 cycloaddition with epoxides under atmospheric pressure with or without cocatalyst TBAB (n-Bu4NBr).

A MOF-membrane based on the covalent bonding driven assembly of a NMOF with an organic oligomer and its application in membrane reactors.

A UiO-66-MOF-based membrane UiO-66-TEM (1) was prepared by the assembly of methacrylamide-decorated UiO-66-NH-Met with a thiol side chain-attached polysiloxane (PSI-SH) via a photoinduced thiol-ene click reaction. The obtained membrane 1 can be a platform to support Au nanoparticles (Au NPs) to generate an Au-MOF-polymer composite membrane Au@UiO-66-TEM (2). 1 and 2 can be used to build highly efficient continuous flow-through membrane reactors for Knoevenagel condensation of 4-nitrobenzaldehyde with malononitrile and 4-nitrophenol (4-NP) reduction at ambient temperature, respectively.

A N-heterocyclic tetracarbene Pd(ii) moiety containing a Pd(ii)-Pb(ii) bimetallic MOF for three-component cyclotrimerization via benzyne.

A novel Pd(ii)-Pb(ii) bimetallic metal-organic framework Pd(ii)-Pb(ii)-MOF (B) which contains an N-heterocyclic tetracarbene Pd(ii) moiety was synthesized based on a chelating N-heterocyclic dicarbene Pd(ii)-NHDC ligand (A) under solvothermal conditions. It can be a highly active heterogeneous catalyst for three-component cyclotrimerization via benzyne species.

Post-Synthetic Polymerization of UiO-66-NH2 Nanoparticles and Polyurethane Oligomer toward Stand-Alone Membranes for Dye Removal and Separation.

Metal-organic frameworks (MOFs) are widely used as porous materials in the fields of adsorption and separation. However, their practical application is largely hindered by limitations to their processability. Herein, new UiO-66-Urea-based flexible membranes with MOF loadings of 50 (1), 60 (2), and 70 wt % (3) were designed and prepared by post-synthetic polymerization of UiO-66-NH2 nanoparticles and a polyurethane oligomer under mild conditions. The adsorption behavior of membrane 3 towards four hydrophilic dyes, namely, eosin Y (EY), rhodamine B (RB), malachite green (MG), and methylene blue (MB), in aqueous solution was studied in detail. It exhibits strong adsorption of EY and RB but weak adsorption of MG and MB in aqueous solution. Owing to the selective adsorption of these hydrophilic dyes, membrane 3 can remove EY and RB from aqueous solution and completely separate EY/MB, RB/MG, and RB/MB mixtures in aqueous solution. In addition, the membrane is uniformly textured, easily handled, and can be reused for dye adsorption and separation.