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The lack of functional groups or binding sites largely hindered the broad application of microporous organic networks (MONs). Herein, we report the fabrication of the sulfonate group-enriched magnetic MON composite (MMON-SO3H@SO3Na) via the combination of the sulfonic acid group containing the monomer and thiol-yne click postmodification for efficient magnetic solid-phase extraction (MSPE) of benzimidazole fungicides (BZDs) from complex sample matrices. The well-defined core-shell-structured MMON-SO3H@SO3Na was obtained and served as an advanced adsorbent for MSPE for concentrating and monitoring trace BZDs. The MMON-SO3H@SO3Na with numerous sulfonate groups provides plenty of ion-exchange, hydrogen-bonding, and π-π sites, leading to the favorable affinity to BZDs via multiple interaction mechanisms. The MMON-SO3H@SO3Na-based MSPE-high-performance liquid chromatography method afforded a wide linear range, low limits of detection, large enrichment factors, good precisions, and reusability for BZDs. Trace BZDs in complex vegetables and fruit samples were successfully detected by the established method. The MMON-SO3H@SO3Na also exhibited good selectivity toward multiple types of polar contaminants containing hydrogen-bonding sites and aromatic structures. This work provided a new postsynthesis strategy for constructing novel and multifunctioned magnetic MONs for preconcentration of trace analytes in a complex matrix.

Microporous organic networks (MONs) are promising in high performance liquid chromatography (HPLC) with large specific surface area, good hydrophobicity and stability. However, their superhydrophobic structures restrict MONs-based HPLC only in reversed-phase mode. To decrease the hydrophobicity of pristine MONs and to expand their broad application in HPLC, here we described the monomer-mediated fabrication of core-shell MON-2COOH@SiO

Design of stable adsorbents for selective gold recovery with large capacity and fast adsorption kinetics is of great challenge, but significant for the economy and the environment. Herein, we show the design and preparation of an irreversible amide-linked covalent organic framework (COF) JNU-1 via a building block exchange strategy for efficient recovery of gold. JNU-1 was synthesized through the exchange of 4,4'-biphenyldicarboxaldehyde (BA) in mother COF TzBA consisting of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)trianiline (Tz) and BA with terephthaloyl chloride. The irreversible amide linked JNU-1 gave good stability, unprecedented fast kinetics, excellent selectivity and outstanding adsorption capacity for gold recovery. X-ray photoelectron spectroscopy along with thermodynamic study and quantum mechanics calculation reveals that the excellent performance of JNU-1 for gold recovery results from the formation of hydrogen bonds C(N)-H⋅⋅⋅Cl and coordinate interaction of O and Au. The rational design of irreversible bonds as both inherent linkage and functional groups in COFs is a promising way to prepare stable COFs for diverse applications.

Development of efficient adsorbents for nitrate removal is vital for tackling increasing nitrate contamination. We report a free-radical polymerization strategy to prepare a cationic surfactant-modified covalent organic framework (DhaTab-S) for removing nitrate ions from aqueous solution. DhaTab-S was prepared by grafting a cationic surfactant diallyldimethylammonium chloride solution on vinyl-containing COF (DhaTab-V). The adsorption capacity for nitrate was pH-dependent with the maximum at pH 6, and the adsorption process was largely influenced by ionic strength. The adsorption equilibrium for nitrate on DhaTab-S was reached within 40 minutes and followed pseudo-second-order kinetics. DhaTab-S showed a nitrate adsorption capacity of 108.8 mg g-1 , which is about 15 times that of COF before surfactant modification. The large adsorption capacity makes DhaTab-S a promising candidate for nitrate removal from aqueous media.

Ionic covalent organic frameworks (iCOFs), a subclass of COFs, offer a functional platform for diverse applications. However, strong charge repulsion between adjacent layers often leads to low-crystalline iCOFs. Herein, we report a knot-linker planarity control strategy to synthesize a highly crystalline iCOF with C3-symmetric cationic units. More planarity of building blocks gives higher crystallinity of iCOFs, leading to a larger surface area and more exposed binding sites of iCOFs. The highly crystalline iCOF in turn gives larger uptake capacity and faster kinetics than the low-crystalline iCOF and the non-crystalline iCOF, uncovering the significance of crystallinity for the removal of pollutants. The prepared highly crystalline TFPT–TGCl–iCOF exhibits larger saturation sorption capacity (893 mg g−1) than previous adsorbents for 2,4-dichlorophenol. The developed strategy provides a new way to construct highly crystalline iCOFs with C3 symmetric-type cationic sites for various applications.

Microporous organic networks (MONs) are a booming class of functional materials in elimination of environmental pollutants. However, the limit varieties of MONs still restrict their broad applications. Here we report the synthesis of a novel type of crown ether (CE)-based MONs via the coupling between brominated 18-crown-6 ether and different aromatic alkynyls. The constructed CE-based MONs integrates the good conjugation property of MONs and the inherent host-guest binding sites of CE, allowing the ultrafast and efficient adsorption and removal of a typical environmental priority pollutant 2,4,6-trichlorophenol (2,4,6-TCP). The hydrophobic CE-based MONs can also address the recovery challenge of unstable discrete CE in most organic and inorganic solvents. All CE-based MONs displayed fast adsorption kinetics (3 min) and large adsorption capacities (229.1-341.7 mg g

Multifunctional nanoprobes with both imaging and drug delivery capabilities represent an emerging approach to the diagnosis and treatment of tumor. However, poor accumulation in tumor cells and low drug availability are the main limitations for their further application. Here we show a pH-driven targeting nanoprobe with dual-responsive drug release for persistent luminescence imaging and chemotherapy of tumor. The nanoprobe is constructed by conjugating the pH-low-insertion-peptide (pHLIP) to the surface of the core-shell structure of mesoporous silica-coated persistent luminescence nanoparticles (MSPLNPs) with the peptide GFLG and disulfide bond as bridges. The pHLIP functionalized nanoprobe exhibits higher cellular uptake for A549 and HepG2 cells in an acidic extracellular microenvironment (pH < 6.5) than in normal physiological condition (pH 7.4). The nanoprobe possesses well-defined NIR persistent luminescence performance and can be effectively accumulated in the tumor site, leading to the visual HepG2 tumor target imaging without autofluorescence interference. Furthermore, the nanoprobe realizes the dual-responsive release of doxorubicin loaded in the mesoporous channels in systems containing cathepsin B and glutathione, and can effectively kill tumor cells and inhibit the growth of tumor. This integrated nanoprobe possesses great potential for the diagnosis and treatment of tumors with high specificity and efficiency.

Porous organic nanocages (POCs) have received great concern in diverse areas recently. However, a long reaction time as well as a toxic catalyst or solvents are still used to synthesize POCs, which...

Microporous organic networks (MONs) that exhibit good stability and hydrophobicity are promising candidates for performing HPLC separation of small organic compounds. However, their applications in separating large analytes as well as biomolecules are still limited by the microporous nature of MONs. Herein, we demonstrated the fabrication of a MON-functionalized silica (MON@SiO2 ), exhibiting micro and mesopores for the HPLC separations of small drugs as well as large analytes, such as flavones, nonsteroidal anti-inflammatory drugs (NSAIDs), endocrine disrupting chemicals (EDCs), and proteins. MON was successfully modified on SiO2 microspheres to yield the uniform and mono-dispersed MON@SiO2 . The separation mechanisms and performance of the MON@SiO2 packed column were evaluated for a wide range of analytes, including neutral, acidic, basic compounds, drugs and proteins. Compared with commercial C18 and SiO2 -NH2 packed columns, the proposed MON@SiO2 column afforded superior performance in the separations of flavones, NSAIDs, EDCs and proteins. Moreover, the MON@SiO2 column also offered good repeatability with intraday RSDs (n = 7) of < 0.1%, < 2.0%, < 2.3%, and < 0.7% for the retention time, peak height, peak area and half peak width, respectively, for separating EDCs. This work proved the potential of using MONs in the HPLC separations of drugs and proteins. This article is protected by copyright. All rights reserved.

The introduction of a functional moiety into a covalent organic framework (COF) is of great significance in promoting its wide applications. Here we show the one-pot synthesis of carboxyl-functiona...

Here we report the rational design and facile synthesis of hydroxyl-enriched microporous organic networks (MON-OH and MON-2OH) for enhanced and efficient adsorption and removal of a typical brominated flame retardant tetrabromobisphenol A (TBBPA) from aqueous solution. Introducing of hydroxyl groups into MONs’ networks lead to the significant improvement of their hydrophilicity and adsorption capacity for TBBPA. Rely on the good hydrophobicity and predesigned hydrogen bonding sites, the synthesized MON-2OH gave a large adsorption capacity of 326.8 mg g−1 for TBBPA, which is much higher than MONs and many other reported sorbents. The adsorption of TBBPA on MON-2OH followed Langmuir and pseudo-second-order kinetic adsorption models. The TBBPA adsorption capacity was independent on ionic strength (0–30 mg g−1), humic acid (0–40 mg g−1) and pH (5.0–8.0). MON-2OH also gave good stability and reusability and owned good practicability for the removal of TBBPA from wastewater samples. Efficient adsorption and removal of other biphenol pollutants was also achieved on MON-2OH. The adsorption mechanisms of TBBPA on MON-2OH were also well elucidated. This work provides a promising way to design and synthesize efficient adsorbents for TBBPA, which may also promote the design, synthesis and application of functionalized MONs in environmental and material science.

Development of energy-saving and rapid strategies to synthesize novel porous materials for efficient adsorption and removal of environmental pollutants is of great challenge and interest either in environmental science or in chemistry. Here we report a facile room temperature stirring method for rapid synthesis of microporous organic networks (MONs) with large surface area, excellent hydrophobicity, good thermal and solvent stabilities for efficient adsorption and removal of a typical brominated flame retardant tetrabromobisphenol A (TBBPA) from aqueous solution. The adsorption kinetics, isotherms and thermodynamics, effects of pH, ionic strength, humic acid, regeneration and reusability of MONs for TBBPA were studied in detail. The adsorption of TBBPA on MONs followed the pseudo-second-order kinetic and Langmuir adsorption models. Rely on the good π-π and hydrophobic interaction between MONs and TBBPA, a maximum adsorption capacity of 227.3 mg g−1 was realized, which is the largest adsorption capacity for TBBPA among all the reported sorbents up to date now. The large adsorption capacity, rapid adsorption kinetics, good stability and reusability make MONs a highly potential adsorbent for TBBPA removal from aqueous solution. This work may also promote the synthesis and application of MONs in pollutants’ removal.

Development of functional porous materials for efficient elimination of environmental pollutants is of great importance in green chemistry and environmental protection. Here we report the design, s...

We report the design and fabrication of a multifunctional persistent luminescent nanoprobe for imaging guided dual-stimulus responsive and triple-synergistic therapy of drug resistant tumor. The integration of the dual-stimulus of an acidic microenvironment and laser irradiation with the triple-synergistic therapy of doxorubicin, photothermal and siRNA offers excellent therapeutic performance for drug resistant tumor cells with high specificity and little side effects.

Fabrication of novel magnetic porous materials for efficient magnetic adsorption and removal of environmental contaminants still remains great important and interesting in environmental science. Magnetic microporous organic networks (MONs) are a recent class of magnetic microporous materials highly potential in diverse areas. However, the strategies for the fabrication of magnetic MONs or MONs-derived magnetic adsorbents are still quite limited. To further develop novel method for the fabrication of MONs-derived magnetic adsorbents and to extend the application of MONs in environmental science, here we reported a convenient and new method by decorating Fe3+ on MON-2COOH to fabricate MON-derived magnetic porous carbon (MPC) for efficient adsorption and removal of cationic dyes from aqueous solution. The Fe3+ was firstly decorated on -COOH enriched MON-2COOH and then calcined to produce MPC under Ar atmosphere. The obtained MPC were well characterized and conducted to the adsorption of cationic dyes. The porous, negatively charged and unsaturated bond contained MPC gave extremely fast adsorption kinetics for cationic dyes via electrostatic, hydrogen bonding and π-π interactions. The adsorption of malachite green on MPC was fitted well with pseudo-second-order kinetic, Langmuir adsorption and monolayer adsorption models, and gave much faster adsorption kinetics and larger adsorption capacities than anionic dyes. Furthermore, the good superparamagnetic behavior and reusability made MPC could be easily recycled and reused. This work not only provided a new strategy to synthesis MON-derived MPC, but also possessed the potential of magnetic MONs-based adsorbents for the adsorption and removal of cationic dyes or trace contaminants in environment.

Fabrication of novel coatings continues to be an area of great interest and significance in the development and application of stir bar sorptive extraction (SBSE). In this work, a carboxyl-enriched microporous organic network (MON-2COOH) coated stir bar was designed and fabricated as a novel adsorbent for efficient extraction of four phenylurea herbicides (PUHs) before their determination by high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA). The MON-2COOH was represented as an effective adsorbent for PUHs due to its large surface area, rigid porous structure, aromatic pore walls and the desired hydrogen bonding sites of introduced carboxyl groups. Variables affecting the SBSE of target analytes were optimized in detail. Under the optimal extraction conditions, favorable correlation coefficients (R2 > 0.996) in the linear range 0.10–250 μg L−1, low limits of detection (LODs, S/N = 3) of 0.025–0.070 μg L−1 and good enrichment factors (46–49) were obtained. Besides, the proposed SBSE-HPLC-PDA method was successfully applied to determine trace PUHs in food and environmental water samples with recoveries in the range of 80.0–104.8% and the precisions (relative standard deviations, RSDs) lower than 9.9% (n = 3). This work revealed the potential of MONs in SBSE of trace contaminants from environmental samples.

Microporous organic networks (MONs) have shown great potential in diverse domains recently. However, the application of MONs in chiral separation or catalysis has been largely lagged due to the lack of chiral MONs and the challenge to synthesize chiral MONs. Here we report a facile thiol-yne click strategy to post-synthesize chiral MONs for the first application in chiral gas chromatography. Three chiral MONs with different chiral centers were rationally designed and synthesized to fabricate their capillary columns for gas chromatographic resolution of various chiral compounds with better resolution than three commercial chiral capillary columns. These results show the great potential of the thiol-yne click strategy for constructing newly chiral MONs and their application in chiral separation.

Microporous organic networks (MONs) have shown great potential in the removal of environmental contaminants. However, all studies have focused on the design and construction of novel and efficient adsorbents, and the recycling and reuse of adsorbates were disregarded. In this study, we report a feasible approach to synthesize renewable and reusable MONs by using target halogenated contaminants such as tetrabromobisphenol A (TBBPA), 2,3-dichlorophenol (2,3-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) as starting monomers. TBBPA, 2,3-DCP, and 2,4,6-TCP acted as hazardous contaminants and starting monomers for MONs, leading to the recycling of both adsorbents and adsorbates. The obtained TBBPA-MON, 2,3-DCP-MON, and 2,4,6-TCP-MON not only offered good reusability and large adsorption capacity for their elimination but also provided good adsorption for other phenolic contaminants relying on multiple interactions. Density functional theory calculation indicated the dominant role of π-π and hydrophobic interactions and the secondary role of hydrogen bonding interactions during the adsorption process. The used TBBPA-MON could be reused and the eluted TBBPA could be recycled and renewed for the construction of fresh MONs. This study provided a feasible approach to design and synthesize renewable MONs for environmental contaminants.

The separation of racemic compounds is important in many fields, such as pharmacology and biology. Taking advantage of the intrinsically strong chiral environment and specific interactions featured by biomolecules, here we contribute a general strategy is developed to enrich chirality into covalent organic frameworks (COFs) by covalently immobilizing a series of biomolecules (amino acids, peptides, enzymes) into achiral COFs. Inheriting the strong chirality and specific interactions from the immobilized biomolecules, the afforded biomolecules⊂COFs serve as versatile and highly efficient chiral stationary phases towards various racemates in both normal and reverse phase of high-performance liquid chromatography (HPLC). The different interactions between enzyme secondary structure and racemates were revealed by surface-enhanced Raman scattering studies, accounting for the observed chiral separation capacity of enzymes⊂COFs.

Covalent organic frameworks (COFs) have been widely applied in gas capture and separation, but the fluorescent property of COFs with large π-conjugated system tends to be underexplored. Here we report the fluorescent properties of several COFs including TaTa, DhaTab, TRITER-1 and TzDa and the effect of metal ions of Na+, Mg2+, K+, Ca2+, Cu2+, Zn2+, Pb2+, Ag+, Cd2+ and Fe3+ on the fluorescence of these COFs. The results show that only Fe3+ significantly quenched the fluorescence of the studied COFs. The possibility of the four COFs for selective sensing of Fe3+ was demonstrated. The possible mechanism of the effect of Fe3+ on the fluorescence of the COFs was based on the absorption competition quenching.

Activatable fluorescence nanoprobes with only one kind of nanomaterial that can act as both the energy donor and acceptor simultaneously are scarce, but highly desirable for biosensing and bioimaging. In the present study, we reveal the preparation of self-quenched gold nanoclusters as a simple fluorescent turn-on probe for imaging intracellular glutathione. The self-quenched gold nanoclusters are prepared via disulfide bond-induced aggregation of gold nanoclusters. Compared with monodisperse gold nanoclusters, the developed self-quenched gold nanoclusters exhibit weak emission at 735 nm with a 40-nm red shift and much lower quantum yield (0.69%). The prepared self-quenched gold nanoclusters also possess good sensitivity and selectivity for glutathione detection, and are applicable for fluorescent turn-on imaging of intracellular glutathione.

Metastasis is the main cause of death in people with cancer. Early diagnosis and targeted therapy for metastasis is crucial for the survival of the cancer patients. However, metastasis is hard to trace for its small size, dispersed distribution and unvascularized anatomy. Here we report a biomimetic persistent luminescent nanoplatform for noninvasive high-sensitive diagnosis and 808 nm laser controlled photodynamics assisted chemotherapy of metastasis. The nanoplatform is composed of a photosensitizer functionalized persistent luminescent nanoparticle core, a doxorubicin loaded hollow silica interlayer and a cancer cell membrane shell for effective metastasis theranostic. The cancer cell membrane shell prevents drug leakage and endows the nanoplatform with targeting ability to metastasis. The reactivatable persistent luminescence of persistent luminescent nanoparticles not only enables long-term in vivo metastasis tracking, but also provides internal light source for singlet oxygen generation to kill cancer cells and further break the membrane shell for drug release. This work provides a promising strategy to develop persistent luminescence imaging guided theranostic nanoplatforms for early metastasis.

Fluoride excess in water is harmful to human beings. Adsorption is an effective way to remove fluoride in water. Exploring novel and efficient sorbents for fluoride adsorption is very necessary and challenging. In this work, the fluoride adsorption behavior of zirconium fumarate metal-organic framework-801 (MOF-801) in water is studied through batch adsorption experiments. MOF-801 has high and stable adsorption efficiency at pH 2–10. The fluoride adsorption capacity on MOF-801 is neither affected by high ion strength nor other anions including Cl−, NO3− and SO42−. The fluoride adsorption on MOF-801 follows a pseudo-second-order model and the Langmuir equation. The fluoride adsorption capacity of MOF-801 is 40 mg g−1 at 303 K, changing little with temperature. The effective defluoridation of MOF-801 resulted from the ion exchange of fluoride ions and hydroxyl group in MOF-801. The practical use of MOF-801 for fluoride adsorption from real water sample reveals the potential of MOF-801 as an efficient adsorbent for the removal of fluoride from water.

Covalent organic frameworks (COFs) are a new class of multifunctional crystalline organic polymer constructed with organic monomers via robust covalent bonds. The unique properties such as convenient modification, low densities, large specific surface areas, good stability and permanent porosity make COFs great potential in separation science. This review shows the state-of-the art for the application of COFs and their composites in analytical separation science. COFs and their composites have been explored as promising sorbents for solid phase extraction, potential coatings for solid phase microextraction, and novel stationary phases for gas chromatography, high-performance liquid chromatography and capillary electrochromatography. The prospects of COFs for separation science are also presented, which can offer an outlook and reference for further study on the applications of COFs.

Chiral metal–organic frameworks (MOFs) show great potential in chiral catalysis and separation. However, their application is still hindered by the limited availability of chiral MOFs and chiral recognition centers due to the great challenges for direct synthesis of chiral MOFs with designed chiral recognition sites. Here we report a post-synthesis approach for the facile preparation of chiral MOFs for chiral gas chromatography. Five chiral MOFs with an identical parent framework but different chiral recognition sites were synthesized via grafting various chiral recognition sites of ligands onto MIL-101–NH2. The chiral MOF-coated capillary columns gave good resolution for the separation of diverse racemates with superior separation to the commercial chiral capillary columns. The results reveal that the post-synthesis approach is convenient to fabricate target chiral MOFs with pre-designed functions with the ability to avoid blind synthesis of chiral MOFs via direct synthesis and to facilitate the evolution of chiral stationary phases in chiral chromatography.

As an effective sample pretreatment approach, stir bar sorptive extraction (SBSE) has shown great prospects in static microextraction and selective enrichment. In this work, bifunctional microporous organic network (B-MON) with the coexistence of amino and hydroxyl groups was firstly designed and synthesized as a novel coating for efficient SBSE of parabens and flavors in combination with high-performance liquid chromatography coupled with photodiode array detection (HPLC-PDA). Linked by covalent bonds to form an extension of the aromatic ring skeleton, B-MON was a tailored adsorbent featured by porous structure and abundant hydrogen bonding sites for analytes with benzene/naphthalene rings and OH/ COOH groups. The extraction and desorption parameters were evaluated in detail. Under the optimized conditions, the proposed B-MON-SBSE-HPLC-PDA method offered good linearity (0.10–100 μg L−1) with correlation coefficients R2 ≥ 0.995, low limits of detection (0.010–0.035 μg L−1) and limits of quantification (0.035–0.115 μg L−1), and favorable enrichment factors (40–49). Furthermore, the developed method has been applied to the analysis of parabens and flavors in cosmetic and food samples with recoveries ranging from 80.4 to 109.6%. This method was also feasible to extract the analytes with benzene/naphthalene rings and OH/ COOH groups, such as the plant growth regulators and non-steroidal anti-inflammatory drugs. The present study provided a new way to synthesize bifunctional MONs for SBSE of trace analytes in complex samples.

Development of novel functionalized adsorbents for efficient magnetic solid phase extraction (MSPE) is essential for promoting their versatile applications in sample pretreatment. Herein, we report the fabrication of a new polyethyleneimine-600 decorated magnetic microporous organic network nanosphere (Fe3O4@MON-PEI600) for effective MSPE of trace non-steroidal anti-inflammatory drugs (NSAIDs) from different water samples. The core-shelled Fe3O4@MON-PEI600 integrates the synergistic effects of Fe3O4, MON and PEI600, providing facile and effective extraction to NSAIDs via multiple hydrogen bonding, π-π and hydrophobic interactions. The inner MON shell employs π-π and hydrophobic interaction sites and the outer PEI-600 coat acts as the hydrogen bonding doner/receptor, which affords good extraction performance for NSAIDs. Under optimal conditions, the Fe3O4@MON-PEI600-MSPE-HPLC-UV method gives wide linear range (0.14–400 μg L−1), low limits of detection (0.042–0.149 μg L−1), good precisions (intra-day and inter-day RSDs

Herein, we report the fabrication of a novel, well-defined core-double-shell-structured magnetic Fe3O4@polydopamine@naphthyl microporous organic network (MON), Fe3O4@PDA@NMON, for the efficient magnetic extraction of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and p-nitrophenol (p-Npn) from wastewater samples. The hierarchical nanospheres were designed and constructed with the Fe3O4 nanoparticle core, the inner shell of a polydopamine (PDA) layer, and the outer shell of a porous naphthyl MON (NMON) coating, allowing efficient and synergistic extraction of OH-PAHs and p-Npn via hydrophobic, hydrogen bonding, and π-π interactions. The Fe3O4@PDA@NMON nanospheres were well characterized and employed as an efficient sorbent for magnetic solid-phase extraction (MSPE) coupled with high performance liquid chromatography (HPLC) for analyzing of OH-PAHs and p-Npn. Under optimal conditions, the Fe3O4@PDA@NMON-based-MSPE-HPLC-UV method afforded wide linear range (0.18-500 μg L-1), low limits of detection (0.070 μg L-1 for p-Npn, 0.090 μg L-1 for 2-OH-Nap, 0.090 μg L-1 for 9-OH-Fluo and 0.055 μg L-1 for 9-OH-Phe, respectively), large enrichment factors (92.6-98.4), good precisions (intra-day and inter-day relative standard deviations (RSDs)

Microporous organic networks (MONs) are a new class of advanced porous materials built from versatile aromatic alkynes and halides via Sonogashira coupling. The extremely large surface areas, excellent solvent and thermal stabilities, tunable pore sizes and functions, as well as convenient post-modification and easy engineering on other matrices make MONs highly convincing in analytical chemistry from sample pretreatment to chromatographic separation. This review briefly introduces recent application and progress of MONs and MONs-based composites in separation science including solid phase extraction, solid phase microextraction, gas chromatography and high-performance liquid chromatography. In the end, the challenge and outlook about the application of MONs in separation science are also presented.

Summary We show that CMOM-3S, a previously unreported porous crystalline metal-organic material that exhibits intrinsic homochirality, serves as a general-purpose chiral crystalline sponge (CCS) and a chiral stationary phase (CSP) for gas chromatography (GC). The properties of CMOM-3S are enabled by nano-sized channels connected to adaptable molecular recognition sites that mimic enzyme-binding sites. Further, CMOM-3S is composed of inexpensive components, facile to prepare, and requires only trace amounts of analyte. When coupled with the thermal and hydrolytic stability of CMOM-3S, these features mean that a coated fused silica capillary column in which CMOM-3S serves as a CSP is both more versatile and more robust than three benchmark commercial columns. That the enantiomer with the longer GC retention time is consistently captured in CCS experiments enables CMOM-3S to serve as a powerful tool to enable both chiral purification and enantiomer identification.

We show a theranostic nanoplatform for messenger RNA (mRNA) triggered enhanced fluorescence imaging guided therapy. Catalytic hairpin assembly (CHA) and gold nanorods (AuNRs) are employed to fabricate the theranostic nanoplatform. Two hairpin DNAs and Cy5 labeled duplex DNA are integrated into the CHA for mRNA triggered fluorescence signal amplification via hybridization and displacement with mRNA. The AuNRs act both as the fluorescence quencher and the photothermal therapy (PTT) agent. The nanoplatform not only enables sensitive and specific imaging of target mRNA in living cells and good differentiating of the survivin mRNA expression levels in different cell lines but also offers excellent photothermal conversion efficiency for PTT. The developed nanoplatform has great potential for sensitive and specific intracellular mRNA imaging guided PTT.

A facile, in situ growth strategy for the synthesis of monodispersed COF@SiO2 microspheres is reported. The microspheres have uniform and controllable COF shells, and are used as the stationary phase for HPLC. The TpBD COF, constructed from 1,3,5-triformylphloroglucinol (Tp) and benzidine (BD), is taken as the COF shell, and aminosilica (SiO2 -NH2 ) is employed as the core to support the TpBD shell. The TpBD shell thickness is adjusted by controlling the concentrations of the Tp and BD monomers. The TpBD@SiO2 packed columns show excellent hydrophobic selectivity, and good reproducibility for the separation of neutral (toluene and ethylbenzene, polycyclic aromatic hydrocarbons), acidic (hydroquinone, p-cresol, and p-chlorophenol), and basic molecules (nucleobases, nucleosides, and deoxynucleosides).

Covalent-organic frameworks (COFs) are a newfangled class of intriguing microporous materials. Considering their unique properties, COFs should be promising as packing materials for high performance liquid chromatography (HPLC). However, the irregular shape and sub-micrometer size of COFs synthesized via the traditional methods render the main obstacles for the application of COFs in HPLC. Herein, we report the preparation of methacrylate-bonded COF monolithic columns for HPLC to overcome the above obstacles. The prepared COF bonded monolithic columns not only show good homogeneity and permeability, but also give high column efficiency, good resolution and precision for HPLC separation of small molecules including polycyclic aromatic hydrocarbons, phenols, anilines, nonsteroidal anti-inflammatory drugs and benzothiophenes. Compared with the bare polymer monolithic column, the COF bonded monolithic columns show enhanced hydrophobic, π-π and hydrogen bond interactions in reverse phase HPLC. The results reveal the great potential of COF bonded monoliths for HPLC and COFs in separation sciences.

The development of the multimodal probes is of great importance for bioimaging application. Herein, we report the fabrication of a functional nanocomposite from near-infrared (NIR) persistent luminescent nanoparticles (PLNPs) and Gd2O3 as a multimodal probe for in vivo NIR persistent luminescence and magnetic resonance (MR) imaging. Small-sized monodispersed NIR ZnGa2O4:Cr3+ PLNPs (ca. 15 nm) were prepared as the NIR persistent luminescence source by a hydrothermal method while hyaluronic acid (HA) functionalized Gd2O3 (HA-Gd2O3) was synthesized as the MR contrast agent via a biomineralization approach. An EDC/NHS coupling strategy was used to connect the amino functionalized PLNPs and the HA-Gd2O3 to give the HA functionalized multimodal probe. The multimodal probe not only exhibits an excellent NIR persistent luminescence signal, but also exhibits larger longitudinal relaxivity (7.38 mM−1 s−1) than commercial contrast agent Gd-DTPA. Moreover, the HA moieties not only enhance the biocompatibility of the multimodal probe, but also endow the probe with tumor-targeting capability. Both in vitro and in vivo bioimaging experiments demonstrate the potential of the multimodal probe for tumor-targeting NIR persistent luminescence and MR imaging.

We report a thiol-ene click strategy for the preparation of a novel phenylboronic acid-functionalized covalent organic framework (COF) for selective removal of catechol in aqueous solution. Vinyl-functionalized 2,5-diallyloxyterephthalaldehyde (Da-V) was prepared as a building ligand. Da-V was then condensed with 1,3,5-tris(4-aminophenyl)benzene (Tab) to give a vinyl-functionalized COF DhaTab-V. Subsequently, 4-mercaptophenylboronic acid (4-MPBA) was covalently linked on DhaTab-V via thiol-ene click reaction to give phenylboronic acid-functionalized COF DhaTab-PBA. The adsorption isotherms, energetics and kinetics, and reusability of DhaTab-PBA for the adsorption and removal of catechol from aqueous solution were investigated in detail. This phenylboronic acid-functionalized COF is promising as sorbent for selective removal of catechol from aqueous medium with large adsorption capacity and good reusability.

Capture of radioactive TcO4- from nuclear wastes is extremely desirable for waste disposal and environmental restoration. Here, we report the synthesis of hydrolytically stable cationic covalent organic nanosheets (iCON) for efficient uptake of ReO4-, a nonradioactive surrogate of TcO4-. The iCON combines cationic guanidine-based knots with hydroxyl anchored neutral edge units and chloride ions loosely bonded in the pores, rendering extremely fast exchange kinetics toward ReO4- with high uptake capacity of 437 mg g-1 and prominent distribution coefficient of 5.0 × 105. The removal efficiency remains stable over a pH range of 3-12 and allows selective capture of ReO4- in the presence of excessive competing anions such as NO3-, CO32-, PO43- and SO42- with good removal efficiency for ReO4- in a simulated Hanford LAW Melter Recycle Stream. Anion exchange between the ReO4- in solution and the chloride ion in iCON plays dominant role in the adsorption of ReO4-. The iCON shows promise for effective removal of radioactive 99Tc from nuclear waste.

Gold nanoparticles (AuNPs) without surface capping agents are easily aggregated owing to their high surface energy, leading to an unexpected decrease of their catalytic activity. Herein, we report gold nanoparticles decorated covalent organic framework (COF) as mimetic peroxidase for colorimetric detection of mercury. 1,3,5-Tris-(4-formyl-phenyl)triazine (PT) and 4, 4′-azodianiline (Azo) was employed as the monomers to prepare a novel imine based COF PTAzo under solvothermal conditions. AuNPs are further decorated into the PTAzo to form COF-AuNPs hybrid via a citrate reducing method. The COF-AuNPs show high stability, and exhibits enhanced peroxidase mimetic activity in the presence of Hg2+. The Hg2+ concentration dependent peroxidase mimetic activity of COF-AuNPs enables the development of a sensitive and selective method for detection of Hg2+ in aqueous solution. The developed method gives good linearity in the range of 5–300 nM with the limit of detection of 0.75 nM. The results show that Hg2+-enhanced peroxidase mimetic activity of COF-AuNPs offers great potential for the detection of Hg2+ in real samples.

Microporous organic networks (MONs) are a new class of porous materials synthesized via Sonogashira coupling reactions between organic building blocks. Here we report an in situ synthesis approach to fabricate MONs coated capillary column for high resolution GC separation of hydrocarbons. The McReynolds constant evaluation reveals the MONs coated capillary is a non-polar column. The MONs coated capillary column shows good resolution for GC separation of diverse important industrial hydrocarbons such as linear and branched alkanes, alkylbenzenes, pinene isomers, ethylbenzene and styrene, cyclohexane and benzene. The MONs coated capillary column gave a high column efficiency of 1542 plates per meter for hexane and good precision for replicate separations of the selected hydrocarbons with the RSDs of 0.2-0.3, 1.5-3.1, and 1.9-3.3% for retention time, peak height and peak area, respectively. The MONs coated capillary also offered better resolution than commercial Inert Cap-1 and Inert Cap-5 capillary columns for hexane and heptane isomers. These results reveal the potential of MONs as novel stationary phases in GC.

Microporous organic networks (MONs) have shown great promise in separation science recently. Exploring novel, simple and convenient strategy to fabricate MONs coated capillary columns for gas chromatography (GC) still remains challenging but desirable for the development of MONs in chromatographic separation. To extend the potential application of MONs in separation science and to further develop novel method for the fabrication of MONs-based capillary columns, here we demonstrate a novel covalent coupling strategy to fabricate uniform MONs bonded capillary columns for GC separation of position isomers and hydrocarbons. The bare capillary column was firstly modified with (3-bromopropyl)trimethoxysilane to provide bromine sites for coupling with alkynyl monomers. The amino- and hydroxyl-functionalized MONs (MON-NH2 and MON-OH) were then directly grown onto the inner wall of the brominated capillary columns via the covalent coupling between bromine and alkynyl groups. The uniform MON-NH2 and MON-OH bonded capillary columns were obtained and showed good resolution for GC separation of dichlorobenzene, chlorotoluene, bromotoluene, and propylbenzene position isomers and many other hydrocarbons including linear alkanes, alkylbenzenes, pinene isomers, cyclohexane and benzene, ketones and aldehydes. The MONs bonded capillary columns also owned good lifetime and precision for dichlorobenzene isomers with the relative standard deviations (RSDs) of 0.2–0.3%, 1.2–2.1%, and 1.7–2.5% for retention time, peak height and peak area, respectively. In addition, the fabricated MON-NH2 and MON-OH bonded capillary columns offered better resolution than commercial InertCap-1, InertCap-5, InertCap-1701 and InertCap-WAX capillary columns for the separation of chlorotoluene and bromotoluene position isomers. These results revealed the feasibility of covalent coupling strategy to fabricate MONs-based stationary phases in GC, highlighting the potential of MONs in separation science.

Development of efficient adsorbents for the enrichment of trace contaminants from complex matrix still remains great challenge and interest. Here we report the decoration of amino microporous organic network on zeolitic imidazolate framework (ZIF)-67 derived nitrogen-doped carbon (Co@NC-MON-2NH2) for efficient magnetic solid phase extraction (MSPE) of plant growth regulators (PGRs) from vegetables. The ZIF-67 was calcined to produce Co and N co-doped porous carbon (Co@NC), serving as the magnetic separation module and the core for in-situ growth of MON-2NH2 shell. The Co@NC-MON-2NH2 owned large surface area, good magnetic property and stability, giving high affinity to PGRs via multiple extraction mechanisms such as hydrogen bonding, π-π and hydrophobic interactions. Under optimal conditions, the Co@NC-MON-2NH2 based MSPE-HPLC-UV method gave wide linear range, good precisions, large enrichment factors, less adsorbent consumption and low limit of detections for the studied PGRs. The proposed MSPE-HPLC-UV method was also successfully applied to monitor the trace PGRs in diverse vegetables. These results not only revealed the promise of Co@NC-MON-2NH2 in extraction and adsorption of environmental contaminants from complex matrix, but also provided a new way to fabricate magnetic functionalized MONs in environmental science.