Two scandium-based coordination polymers: rapid ultrasound-assisted synthesis, crystal transformation, and catalytic properties

Assisted by ultrasound waves, a Sc-based coordination polymer CP 1 was synthesized successfully. With 1 as the precursor, another stable CP 2 can be obtained by single-crystal to single-crystal transformation and 2 exhibited good catalytic activities.

A stable mixed-valent uranium(v,vi) organic framework as a fluorescence thermometer

A stable mixed-valent uranium(v/vi) organic framework with a 3D interpenetrating structure was synthesized, which can be used as a dual-responsive fluorescence temperature sensor based on the fluorescence intensity and fluorescence lifetime.

Luminescence tuning and sensing properties of stable 2D lanthanide metal–organic frameworks built with symmetrical flexible tricarboxylic acid ligands containing ether oxygen bonds

New Ln-MOFs were yielded by a flexible ligand and lanthanide ions. The colors can be regulated by adjusting the molar ratios of Eu³⁺/Tb³⁺, showing promising applications in NB sensing, tunable photoluminescence and pH sensing.

Lanthanide-based molecular alloys with hydroxyterephthalate: a versatile system

Reactions in water between lanthanide chlorides and the di-sodium salt of 2-hydroxyterephthalic acid (H₂hbdc) lead to six families of lanthanide-based coordination polymers depending on the lanthanide ion and the crystal growth method.

Six CoII coordination polymers exhibiting UV-light-driven photocatalysis for the degradation of organic dyes

Six different Co^II coordination polymers based on a new bis-pyridyl-bis-amide and polycarboxylates were obtained, showing photocatalytic activity for organic dyes.

An ultralight charged MOF as fluoro-switchable monitor for assorted organo-toxins: size-exclusive dye scrubbing and anticounterfeiting applications via Tb3+ sensitization

The trifunctional Li(i)-MOF acts as fluoro-switchable sensor for two organo-toxins, invisible-ink based data encrypter and size–specific dye scavenger, where DFT calculations support sensing and adsorption mechanisms considering extended structure.

Two cluster-based metal–organic frameworks with selective detection of Hg2+ ion and magnetic properties

Two cluster-based metal–organic frameworks have been synthesized—one exhibits highly selective fluorescent detection of trace Hg2+ and the other shows antiferromagnetic interactions between Mn3+ ions.

A nonlinear optical cadmium(ii)-based metal–organic framework with chiral helical chains derived from an achiral bent dicarboxylate ligand

The design of a nonlinear optical (NLO) MOF material from an achiral bent dicarboxylate ligand is presented.

A Y(III)-based Metal-Organic Framework as a Carrier in Chemodynamic Therapy

A biocompatible Y(III)-based metal-organic framework [Y₄(TATB)₂]·(DMF)_3.5·(H₂O) (ZJU-16, H₃TATB= 4,4',4''-(1,3,5-triazine-2,4,6-triyl) tribenzoic acid) was synthesized, and it was adopted to load Mn²⁺ for chemodynamic therapy. Meanwhile, ibuprofen sodium (IBUNa), an anti-inflammatory drug, was introduced to increase the amount of Mn²⁺ (about 5.66 wt %) due to the low loading capacity of Mn²⁺. Mn&IBUNa@ZJU-16 which was loaded by Mn²⁺ and IBUNa exhibited significant effects of chemodynamic therapy and excellent inhibition of the 4T1 tumor cell growth, implying its long-term prospects in chemodynamic therapy and its possibility in bimodal cancer therapy.

Porous and Nonporous Coordination Polymers Induced by Pseudohalide Ions for Luminescence and Gas Sorption

The three-dimensional (3D) coordination polymers [Cd(tpmd)(NCX)₂]_n [X = O (1), S (2), and BH₃ (3); tpmd = N,N,N',N'-tetrakis(pyridin-4-yl)methanediamine] have been determined to display their network structures through coordinated anionic ligands. Polymers 1 and 2 show nonporous structures, whereas polymer 3 shows a porous coordination framework. On the basis of the Cd(II) network structures, the 3D coordination polymer [Zn(tpmd)(NCBH₃)₂]_n·nMeOH (4) was self-assembled. In the cases of polymers 1 and 2, pseudohalide ions acted to form nonporous network structures; however, in polymers 3 and 4, NCBH₃^- helps to construct porous network structures. Polymers 1-4 show strong ultraviolet luminescence emissions, depending on the pseudohalide ions present, compared to the tpmd ligands. Interestingly, coordination polymers 3 and 4 that possess NCBH₃^- ions exhibit high porosities and gas sorption properties. The polymers appeared to absorb N₂, H₂, CO₂, and CH₄. In the case of polymer 4, the structure is almost identical with that of polymer 3, except for the Cd(II) ion. However, polymer 4 has a larger void volume and higher gas absorption ability for N₂ gas than polymer 3. For the sorption of gases, polymers 3 and 4 showed similar behaviors.

Recent Progress on Microfine Design of Metal-Organic Frameworks: Structure Regulation and Gas Sorption and Separation

Metal-organic frameworks (MOFs) have emerged as an important and unique class of functional crystalline hybrid porous materials in the past two decades. Due to their modular structures and adjustable pore system, such distinctive materials have exhibited remarkable prospects in key applications pertaining to adsorption such as gas storage, gas and liquid separations, and trace impurity removal. Evidently, gaining a better understanding of the structure-property relationship offers great potential for the enhancement of a given associated MOF property either by structural adjustments via isoreticular chemistry or by the design and construction of new MOF structures via the practice of reticular chemistry. Correspondingly, the application of isoreticular chemistry paves the way for the microfine design and structure regulation of presented MOFs. Explicitly, the microfine tuning is mainly based on known MOF platforms, focusing on the modification and/or functionalization of a precise part of the MOF structure or pore system, thus providing an effective approach to produce richer pore systems with enhanced performances from a limited number of MOF platforms. Here, the latest progress in this field is highlighted by emphasizing the differences and connections between various methods. Finally, the challenges together with prospects are also discussed.

Controlled Assembly of Luminescent Lanthanide-Organic Frameworks via Post-Treatment of 3D-Printed Objects

Complex multiscale assemblies of metal-organic frameworks are essential in the construction of large-scale optical platforms but often restricted by their bulk nature and conventional techniques. The integration of nanomaterials and 3D printing technologies allows the fabrication of multiscale functional architectures. Our study reports a unique method of controlled 3D assembly purely relying on the post-printing treatment of printed constructs. By immersing a 3D-printed patterned construct consisting of organic ligand in a solution of lanthanide ions, in situ growth of lanthanide metal-organic frameworks (LnMOFs) can rapidly occur, resulting in macroscopic assemblies and tunable fluorescence properties. This phenomenon, caused by coordination and chelation of lanthanide ions, also renders a sub-millimeter resolution and high shape fidelity. As a proof of concept, a type of 3D assembled LnMOFs-based optical sensing platform has demonstrated the feasibility in response to small molecules such as acetone. It is anticipated that the facile printing and design approach developed in this work can be applied to fabricate bespoke multiscale architectures of functional materials with controlled assembly, bringing a realistic and economic prospect.

Recent advances in metal-organic frameworks for pesticide detection and adsorption

The large-scale use of pesticides such as organophosphate pesticides (OPPs) and organochlorine pesticides (OCPs) has led to serious environmental problems worldwide, and their high toxicity could cause serious damage to human health. It is crucial to remove and track them precisely in the environment and food resources. As novel nanomaterials, metal-organic frameworks (MOFs) have attracted significant attention in the fields of adsorption and luminescence sensing due to their rich topology, tunable pore size and shape, high surface area, and abundant active sites. Luminescent metal-organic frameworks (LMOFs) have sprung up as great potential chemical sensors to detect pesticides with fast response, high sensitivity, high selectivity and easy operation. Therefore, in this highlight, we focus on recent progress of MOFs in sensing and adsorbing pesticides, as well as in the possible mechanism of sensing, so as to attract more attention to pesticide detection and adsorption.

Synergetic Effect of Tetraethylammonium Bromide Addition on the Morphology Evolution and Enhanced Photoluminescence of Rare-Earth Metal-Organic Frameworks

Controlled synthesis of rare-earth metal-organic frameworks (RE-MOFs) is of great significance to match their emerging multifunctional luminescence applications. Herein, we propose a green and general solvent-free synthetic strategy for the adjustment of morphology and dimension of various RE-MOFs (RE = Eu, Tb, Er, Dy, Y, Tm) by using a tetraethylammonium bromide-assisted thermal-heating method. These self-assembled RE-MOF materials possess controllable morphologies and hierarchical structures while retaining the structural topology of MIL-78, proving that the strategy is a feasible and effective way in opening up large-scale synthesis of RE-MOFs. It is further found that the tetraethylammonium could be carbonized into carbon dots and encapsulated in Eu/Tb-MIL-78 to enhance the fluorescence emission intensities significantly, making the hierarchical Eu/Tb-MIL-78 MOF materials good candidates for the latent fingerprints recognition application. This work provides a novel strategy for effectively controlling the morphology and dimension of RE-MOFs materials with enhanced photoluminescence and has great potential in their scaling-up syntheses and exploring the new luminescence applications.

Luminescent triphenylamine-based metal-organic frameworks: recent advances in nitroaromatics detection

Luminescent metal-organic frameworks (LMOFs), as one branch of MOFs, have attracted considerable attention in recent years due to their good crystallinity, structural diversity, tunable porosity and easily induced fluorescence emission. Importantly, their photoluminescence (PL) properties can be adjusted by altering metal ions or metal clusters and organic ligands in one hybrid system. Among the various sensing applications, using LMOFs as chemical sensors to detect the explosive and environment pollution causing nitroaromatic compounds (NACs) is an important topic. In this account, we describe the recent advancements in the field of NAC detection by LMOFs based on the triphenylamine (TPA) unit as the π-conjugated fluorophore.

Engineering micromechanics of soft porous crystals for negative gas adsorption

Framework materials at the molecular level, such as metal-organic frameworks (MOF), were recently found to exhibit exotic and counterintuitive micromechanical properties. Stimulated by host-guest interactions, these so-called soft porous crystals can display counterintuitive adsorption phenomena such as negative gas adsorption (NGA). NGA materials are bistable frameworks where the occurrence of a metastable overloaded state leads to pressure amplification upon a sudden framework contraction. How can we control activation barriers and energetics via functionalization of the molecular building blocks that dictate the frameworks' mechanical response? In this work we tune the elastic and inelastic properties of building blocks at the molecular level and analyze the mechanical response of the resulting frameworks. From a set of 11 frameworks, we demonstrate that widening of the backbone increases stiffness, while elongation of the building blocks results in a decrease in critical yield stress of buckling. We further functionalize the backbone by incorporation of sp3 hybridized carbon atoms to soften the molecular building blocks, or stiffen them with sp2 and sp carbons. Computational modeling shows how these modifications of the building blocks tune the activation barriers within the energy landscape of the guest-free bistable frameworks. Only frameworks with free energy barriers in the range of 800 to 1100 kJ mol-1 per unit cell, and moderate yield stress of 0.6 to 1.2 nN for single ligand buckling, exhibit adsorption-induced contraction and negative gas adsorption. Advanced experimental in situ methodologies give detailed insights into the structural transitions and the adsorption behavior. The new framework DUT-160 shows the highest magnitude of NGA ever observed for nitrogen adsorption at 77 K. Our computational and experimental analysis of the energetics and mechanical response functions of porous frameworks is an important step towards tuning activation barriers in dynamic framework materials and provides critical design principles for molecular building blocks leading to pressure amplifying materials.

Controllable broadband multicolour single-mode polarized laser in a dye-assembled homoepitaxial MOF microcrystal

Multicolour single-mode polarized microlasers with visible to near-infrared output have very important applications in photonic integration and multimodal biochemical sensing/imaging but are very difficult to realize. Here, we demonstrate a single crystal with multiple segments based on the host-guest metal-organic framework ZJU-68 hierarchically hybridized with different dye molecules generating controllable single-mode green, red, and near-infrared lasing, with the lasing mode mechanism revealed by computational simulation. The segmented and oriented assembly of different dye molecules within the ZJU-68 microcrystal causes it to act as a shortened resonator, enabling us to achieve dynamically controllable multicolour single-mode lasing with a low three-colour-lasing threshold of ~1.72 mJ/cm2 (approximately seven times lower than that of state-of-the-art designed heterostructure alloys, as reported by Fan F et al. (Nat. Nanotechnol. 10:796-803, 2015) considering the single pulse energy density) and degree of polarization >99.9%. Furthermore, the resulting three-colour single-mode lasing possesses the largest wavelength coverage of ~186 nm (ranging from ~534 to ~720 nm) ever reported. These findings may open a new route to the exploitation of multicolour single-mode micro/nanolasers constructed by MOF engineering for photonic and biochemical applications.

Insights to perfluorooctanoic acid adsorption micro-mechanism over Fe-based metal organic frameworks: Combining computational calculation with response surface methodology

Adsorption performance, interfacial interaction mechanism and contribution of pores concerning PFOA adsorption to Fe-based metal-organic frameworks (MOFs) including Fe-BTC, MIL-100-Fe and MIL-101-Fe are investigated using experiments and computational calculation at molecular level even electronic level. Fe-BTC (418 mg/g) with more Lewis acid sites demonstrates higher adsorption capacity of PFOA in comparison with MIL-100-Fe (349 mg/g) and MIL-101-Fe (370 mg/g). Adsorption isotherms and kinetics indicate presence of monolayer adsorption and chemisorption in adsorption process. The pH dependence of PFOA adsorption to Fe-based MOFs is statistically revealed by experiments and analysis of variance of response surface methodology (RSM). XPS spectra of MOF-PFOA corroborate that decreasing binding energy of Fe2p and increasing binding energy of F1s, suggesting the presence of Lewis acid/base complexing (LAB) and hydrophobic interaction in adsorption process. Differential charge demonstrates that Fe center and benzene of organic ligands are respectively electron acceptor and donor in adsorption process. Electronic level mechanism finds that LAB complexing dominates adsorption process due to highest overlap of electron cloud. Smaller pores such as triangle and pentagonal pores of Fe-based MOFs contribute to the load of PFOA, while larger hexagonal one enable PFOA to enter into cages, as revealed by computational calculation.

High Luminance of Heterolanthanide-Based Molecular Alloys by Phase-Induction Strategy

Reactions in water of lanthanide chlorides with the sodium salt of 4,5-dichlorophthalate (dcpa^2-) lead to two families of isostructural coordination polymers: family F1 that gathers compounds with the general chemical formula [Ln₂(dcpa)₃(H₂O)]_∞ with Ln = La-Gd (except Pm) and family F2 that gathers compounds with general chemical formula [Ln₂(dcpa)₃(H₂O)₅·3H₂O]_∞ with Ln = Tb-Lu plus Y. Heterolanthanide molecular alloys that contain both Eu³⁺ and Tb³⁺ ions have been prepared in both structural families. Their luminescence properties have been studied, especially from the brightness point of view. This study revealed that structural family F1 provides molecular alloys that are much more luminescent than those of structural family F2. Therefore, a phase-induction strategy was followed that allowed the design of some molecular alloys (La/Tb/Eu and La/Dy) that are, to the best of our knowledge, among the most luminescent coordination polymers reported so far. This study opens the way to bright luminescent bar codes as well as to bright white luminescent lanthanide-based coordination polymers.

Luminescent lanthanide metal-organic framework nanoprobes: from fundamentals to bioapplications

Metal-organic frameworks (MOFs), a unique type of porous material characterized by high porosity, large internal surface area and remarkable structural tunability, have emerged as very attractive functional materials for a variety of applications. As a promising subclass of MOFs, lanthanide metal-organic frameworks (Ln-MOFs) integrate the unique advantages of MOFs and the intrinsic features of lanthanide ions, such as sharp emission bands, long luminescent lifetimes, large Stokes shifts, high color purity and high resistance to photobleaching. In this minireview, we provide a brief overview of the most recent advances in luminescent Ln-MOF nanoprobes, which covers from their chemical and physical fundamentals to bioapplications, including their synthetic strategies, optical properties and promising bioapplications in biodetection, bioimaging and therapy. Finally, some of the most important emerging trends and future efforts toward this rapidly evolving field are also envisioned.

Rational Design of Dual IR and Visible Highly Luminescent Light-Lanthanides-Based Coordination Polymers

A series of isostructural homo- and heterolanthanide coordination polymers of formula [Ln₂(dcpa)₃(H₂O)]_∞ with Ln = La-Gd have been obtained by reactions in water between the lightest lanthanide chlorides and the disodium salt of 4,5-dichlorophthalic acid (H₂dcpa). They present particularly high thermal stability for coordination compounds (up to 400 °C). Their luminescent properties have been studied in detail. Interestingly an insensitivity to water coordination as well as a very strong effect of optical dilution is observed. Therefore, molecular alloys with very high lanthanum concentration have been prepared. Some of them present highly tunable and very intense luminescence. For example, to the best of our knowledge, [Sm_0.04La_1.96(dcpa)₃(H₂O)]_∞ presents one of the highest overall quantum yields measured so far for a Sm³⁺-based coordination compound (Q_Sm^Ligand = 9.2%), and [Nd_0.03Sm_0.14Eu_0.03La_1.8(dcpa)₃(H₂O)]_∞ is one of the brightest (12 Cd·m^-2 under 0.75 mW·cm^-2 UV flux) multiemissive visible and near-infrared lanthanide-coordination polymers reported to date.

The function of metal-organic frameworks in the application of MOF-based composites

In the last two decades, metal-organic frameworks (MOFs), as a class of porous crystalline materials formed by organic linkers coordinated-metal ions, have attracted increasing attention due to their unique structures and wide applications. Compared to single components, various well-designed MOF-based composites combining MOFs with other functional materials, such as nanoparticles, quantum dots, natural enzymes and polymers with remarkably enhanced or novel properties have recently been reported. To efficiently and directionally synthesize high-performance MOF-based composites for specific applications, it is vital to understand the structural-functional relationships and role of MOFs. In this review, preparation methods of MOF-based composites are first summarized and then the relationship between the structure and performance is determined. The functions of MOFs in practical use are classified and discussed through various examples, which may help chemists to understand the structural-functional relationship in MOF-based composites from a new perspective.

Metal–Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) Applied to Photocatalytic Organic Transformations

Among the different alternatives for catalysis using metal–organic frameworks (MOFs) or covalent organic frameworks (COFs), photocatalysis has remarkably evolved during the last decade. Photocatalytic reticular materials allowed recyclability and easy separation of catalyst from the product, also reaching the activity and selectivity commonly observed for molecular systems. Recently, photocatalytic MOFs and COFs have been applied to synthetic applications in order to obtain organic molecules of different complexity. However, although a good number of works have been devoted to this issue, an updated comprehensive revision on this field is still needed. The aim of this review was to fill this gap covering the following three general aspects: (1) common strategies on the design of reticular photocatalytic materials, (2) a comprehensive discussion of the photocatalytic organic reactions achieved by the use of COFs and MOFs, and (3) some critical considerations highlighting directions that should be considered in order to make advances in the study of photocatalytic COFs and MOFs.

A dual-sensitized luminescent europium(iii) complex as a photoluminescent probe for selectively detecting Fe3

A new luminescent EuIII complex, namely [Eu2(BTFA)4(OMe)2(dpq)2] (1), in which BTFA = 3-benzoyl-1,1,1-trifluoroacetone and dpq = dipyrido [3,2-d:2',3'-f] quinoxaline, has been designed and synthesized by employing two different ligands as sensitizers. Crystal structure analysis reveals that complex 1 is composed of dinuclear EuIII units crystallized in the monoclinic P1̄ space group. Notably, 1 exhibits high thermal stability up to 270 °C and excellent water stability. The photoluminescence property of the complex is investigated. Further studies show 1 can recognize Fe3+ ions with high selectivity from mixed metal ions in aqueous solution through the luminescence quenching phenomenon. Furthermore, the recyclability and stability of 1 after sensing experiments are observed to be adequate. By virtue of the superior stability, detection efficiency, applicability and reusability, the as-prepared EuIII complex can be a promising fluorescent material for practical sensing.

Highly Stable Lanthanide Metal-Organic Framework as an Internal Calibrated Luminescent Sensor for Glutamic Acid, a Neuropathy Biomarker

Glutamic acid (Glu) is the most abundant excitatory neurotransmitter in the central nervous system, and an elevated level of Glu may indicate some neuropathological diseases. Herein, three isomorphic microporous lanthanide metal-organic frameworks (MOFs) [(CH₃)₂NH₂]₂[Ln₆(μ₃-OH)₈(BDC-OH)₆(H₂O)₆]·(solv)_x (ZJU-168; ZJU = Zhejiang University, H₂BDC-OH = 2-hydroxyterephthalic acid, Ln = Eu, Tb, Gd) were designed for the detection of Glu. ZJU-168(Eu) and ZJU-168(Tb) suspensions simultaneously produce the characteristic emission bands of both lanthanide ions and ligands. When ZJU-168(Eu) and ZJU-168(Tb) suspensions exposed to Glu, the fluorescence intensity of ligands increases while the emission of lanthanide ions is almost unchanged. By utilizing the emission of ligands as the detected signal and the emission of lanthanide ions as the internal reference, an internal calibrated fluorescence sensor for Glu was obtained. There is a good linear relationship between fluorescence intensity ratio and Glu concentration in a wide range with the detection limit of 3.6 μM for ZJU-168(Tb) and 4.3 μM for ZJU-168(Eu). Major compounds present in blood plasma have no interference for the detection of Glu. Furthermore, a convenient analytical device based on a one-to-two logic gate was constructed for monitoring Glu. These establish ZJU-168(Tb) as a potential turn-on, ratiometric, and colorimetric fluorescent sensor for practical detection of Glu.

Structure Engineering of a Lanthanide-Based Metal-Organic Framework for the Regulation of Dynamic Ranges and Sensitivities for Pheochromocytoma Diagnosis

Exploring innovative technologies to precisely quantify biomolecules is crucial but remains a great challenge for disease diagnosis. Unfortunately, the humoral concentrations of most biotargets generally vary within rather limited scopes between normal and pathological states, while most literature-reported biosensors can detect large spans of targets concentrations, but are less sensitive to small concentration changes, which consequently make them mostly unsatisfactory or even unreliable in distinguishing positives from negatives. Herein, a novel strategy of precisely quantifying the small concentration changes of a certain biotarget by editing the dynamic ranges and sensitivities of a lanthanide-based metal-organic framework (Eu-ZnMOF) biosensor is reported. By elaborately tailoring the biosensor's structure and surface areas, the tunable Eu-ZnMOF is developed with remarkably enhanced response slope within the "optimized useful detection window," enabling it to serve as a powerful signal amplifier (87.2-fold increase) for discriminating the small concentration variation of urinary vanillylmandelic acid (an early pathological signature of pheochromocytoma) within only three times between healthy and diseased subjects. This study provides a facile approach to edit the biosensors' performances through structure engineering, and exhibits promising perspectives for future clinical application in the non-invasive and accurate diagnosis of severe diseases.

Four-dimensional metal-organic frameworks

Recognising timescale as an adjustable dimension in porous solids provides a new perspective to develop novel four-dimensional framework materials. The deliberate design of three-dimensional porous framework architectures is a developed field; however, the understanding of dynamics in open frameworks leaves a number of key questions unanswered: What factors determine the spatiotemporal evolution of deformable networks? Can we deliberately engineer the response of dynamic materials along a time-axis? How can we engineer energy barriers for the selective recognition of molecules? Answering these questions will require significant methodological development to understand structural dynamics across a range of time and length scales.

Developing a Novel Nanoscale Porphyrinic Metal-Organic Framework: A Bifunctional Platform with Sensitive Fluorescent Detection and Elimination of Nitenpyram in Agricultural Environment

Developing a rapid sensing platform with effective pesticide degradation capabilities integrated into a single structure and realistic application is an imminent challenge to ensure sustainable agriculture and food safety. Here, we described establishment of a bifunctional nanoscale porphyrinic metal-organic framework (MOF) probe serving as a sensor for detection of trace nitenpyram and as a photocatalyst to facilitate the pesticide degradation. Based on the signal turned "on-off", the strong fluorescence of the probe was quenched by the target, leading to the sensing range from 0.05 to 10.0 μg mL^-1 and a detection limit of 0.03 μg mL^-1. Given the versatile design by which the porphyrin photosensitizers were isolated subtly in the MOF to avoid self-quenching, the probe was endowed with sustainable and efficient pesticide photodegradation activity with a degradation rate of ∼95% for nitenpyram. Our work represents powerful all-in-one MOF-derived materials jointly for sensing and degrading pesticide residues in agricultural soils and other pesticide-contaminated environments.

Highly Efficient Separation of Anionic Organic Pollutants from Water via Construction of Functional Cationic Metal-Organic Frameworks and Mechanistic Study

Organic anions possess various functional properties; however, their presence in wastewater causes environmental pollution. Thus, coupling the separation of such species with the resultant function could be highly desirable. Herein, we propose a "killing two birds with one stone" strategy for highly efficient separation of organic pollutant anions from water at room temperature through direct construction of functional cationic metal-organic frameworks (CMOFs) based on the organic anions as charge-balancing anions. To illustrate this strategy, 2,4,6-trinitrophenolate anion (PA^-) is chosen as a typical anion, while 4,4'-azo-triazole (atrz) is strategically chosen as a suitable neutral ligand. The resultant positive framework exhibits a high adsorption capacity and selectivity for PA^-. Remarkably, its adsorption capacity is 869.6 mg g^-1, which is more than 30 times that of multiwalled carbon nanotubes and 15 times that of activated carbon. Its capacity is even higher than that of BUT-13 (865 mg g^-1), the highest adsorbent ever known. ¹H NMR and single-crystal X-ray diffraction show that the high capacity is attributed to strong electrostatic interaction between the positive framework and PA^-, which leads to all the pores being completely occupied by PA^- anions. ¹H NMR titration reveals that the selectivity comes from stronger hydrogen-bonding interaction between the ligand of the positive framework and PA^-, which is confirmed from the eight times length of the shifted signal of atrz due to the addition of PA^- compared with the competing anions. The stronger interaction is further confirmed from the high stability of the resultant CMOF in high-concentration salt solutions containing the competing anions, particularly in 100-fold molar NaNO₃ and Na₂SO₄ solutions. Meanwhile, first-principles simulation shows that the high binding energy between the positive framework and PA^- contributes to enhancing the selectivity. Moreover, the resultant CMOF is a potential energetic material with an improved oxygen balance, high heat of formation, and heat of detonation.

Multiresponsive White-Light Emitting Aerogel Prepared with Codoped Lanthanide/Thymidine/Carbon Dots

Aerogels hold great promise as a lightweight replacement in materials fields. Dynamic fluorochromic aerogels that possess reversible stimuli responsiveness have been particularly attractive recently for new design opportunities in practical solid-state lighting and wide applications in advanced sensors/probe. In this study, we report a reversibly multiresponsive white-light-emitting (WLE) aerogel prepared with codoped lanthanide, thymidine, and carbon dots. By precisely modulating the stoichiometric ratio of lanthanide complexes and carbon dots, broad-spectrum output from purple to red is obtained, including pure white light (CIE (0.33, 0.32)). The freeze-drying process contributes to the elimination of hydration between water molecules and lanthanide ions, further preventing the quenching of lanthanide luminescence and preserving the high quantum yield (47.4%) of our aerogel. Moreover, the dynamic coordination bond between lanthanide (europium and terbium) and thymidine endows the aerogel with reversible responsiveness upon five different stimuli, including halide anions, metal ions, pH, temperature, and humidity. We envision that our WLE aerogel has considerable potential for use in various fields such as display devices, advanced sensors, and environmentally friendly probes where multiresponsiveness is required.

Chiral Cux OS@ZIF-8 Nanostructures for Ultrasensitive Quantification of Hydrogen Sulfide In Vivo

In this study, a Cu_x OS@ZIF-8 nanostructure is fabricated to quantify the levels of hydrogen sulfide (H₂ S) in living cells and in vivo. Zeolitic lmidazolate framework-8 (ZIF-8) is chosen as an encapsulation shell to improve the selectivity of this probe. Using this unique nanostructure, ultrasensitive quantification and bioimaging of H₂ S in living cells are successfully achieved. The lower limit of detection is 0.8 and 5.3 nmol per 10⁶ cells for circular dichroism and fluorescence modes, respectively. It is found that the chiral Cu_x OS NPs transformed into achiral Cu_x S NPs contribute to the ultrasensitive detection. Notably, this probe can also be carried out to detect and track H₂ S levels in tumor-bearing animals. The discoveries put forward for the creation of a detection platform for quantitative tracking and analysis in clinic.

Metal-Organic Framework Nanoparticles Induce Pyroptosis in Cells Controlled by the Extracellular pH

Ion homeostasis is essential for cellular survival, and elevated concentrations of specific ions are used to start distinct forms of programmed cell death. However, investigating the influence of certain ions on cells in a controlled way has been hampered due to the tight regulation of ion import by cells. Here, it is shown that lipid-coated iron-based metal-organic framework nanoparticles are able to deliver and release high amounts of iron ions into cells. While high concentrations of iron often trigger ferroptosis, here, the released iron induces pyroptosis, a form of cell death involving the immune system. The iron release occurs only in slightly acidic extracellular environments restricting cell death to cells in acidic microenvironments and allowing for external control. The release mechanism is based on endocytosis facilitated by the lipid-coating followed by degradation of the nanoparticle in the lysosome via cysteine-mediated reduction, which is enhanced in slightly acidic extracellular environment. Thus, a new functionality of hybrid nanoparticles is demonstrated, which uses their nanoarchitecture to facilitate controlled ion delivery into cells. Based on the selectivity for acidic microenvironments, the described nanoparticles may also be used for immunotherapy: the nanoparticles may directly affect the primary tumor and the induced pyroptosis activates the immune system.