Porphyrinic MOF Film for Multifaceted Electrochemical Sensing

Electrochemical sensing mechanisms of neonicotinoid pesticides and recent progress in utilizing functional materials for electrochemical detection platforms

The excessive residue of neonicotinoid pesticides in the environment and food poses a severe threat to human health, necessitating the urgent development of a sensitive and efficient method for detecting trace amounts of these pesticides. Electrochemical sensors, characterized by their simplicity of operation, rapid response, low cost, strong selectivity, and high feasibility, have garnered significant attention for their immense potential in swiftly detecting trace target molecules. The detection capability of electrochemical sensors primarily relies on the catalytic activity of electrode materials towards the target analyte, efficient loading of biomolecular functionalities, and the effective conversion of interactions between the target analyte and its receptor into electrical signals. Electrode materials with superior performance play a crucial role in enhancing the detection capability of electrochemical sensors. With the continuous advancement of nanotechnology, particularly the widespread application of novel functional materials, there is paramount significance in broadening the applicability and expanding the detection range of pesticide sensors. This comprehensive review encapsulates the electrochemical detection mechanisms of neonicotinoid pesticides, providing detailed insights into the outstanding roles, advantages, and limitations of functional materials such as carbon-based materials, metal-organic framework materials, supramolecular materials, metal-based nanomaterials, as well as molecular imprinted materials, antibodies/antigens, and aptamers as molecular recognition elements in the construction of electrochemical sensors for neonicotinoid pesticides. Furthermore, prospects and challenges facing various electrochemical sensors based on functional materials for neonicotinoid pesticides are discussed, providing valuable insights for the future development and application of biosensors for simplified on-site detection of agricultural residues.

Ultrasensitive cortisol electrochemical immunosensor amplifying by Au single-atom nanozymes and HRP enzymes

Cortisol, a corticosteroid hormone as a primary stress hormone response to internal and external stress, has been regarded as a gold standard reliable biomarker to evaluate human mental stress. The double enzymes strategy, using nanozyme and enzyme amplifying the electrochemical signal, has been widely used to improve the performance of electrochemical biosensors. An ultra-sensitive electrochemical cortisol sensor based on Au single-atom nanozymes had been fabricated through HRP labeled anti-cortisol antibody binding with Au by Au-S bond. Based on the high catalytic activity of Au single-atom nanozymes and the high selectivity of HRP-labeled anti-cortisol antibodies, the cortisol electrochemical sensor-based Au single-atom nanozymes had an excellent response to cortisol, such as high electrochemical activity, high sensitivity, high selectivity, and wide linear range (0.15-300 ng mL-1) and low detection (0.48 pg mL-1) through the four-parameter logistic model with 95% confidence. The electrochemical cortisol sensor was used to determine the cortisol concentration of human saliva at different times.

Bottom-Up Construction of Rhombic Lamellar CoNi-MOFs for the Electrochemical Sensing of H2S

Lamellar metal-organic frameworks (MOFs) have attracted significant attention in the field of electrochemical sensing due to their abundant open active sites and specific electron conductivity. Herein, by employing a bottom-up synthesis strategy, rhombic lamellar heterometallic CoNi-MOFs with varying thicknesses are constructed. This is achieved by using 4-methylpyridine as a capping agent based on the (4,6)-linked Co2(azpy)2(bptc) (azpy = 4,4'-azopyridine, bptc = 3,3',5,5'-biphenyltetracarboxylic acid) structure with a fsc topology and by introducing Ni species simultaneously. To mitigate sulfur deposition on electrodes, the triple pulse amperometry (TPA) method is employed. Among the synthesized lamellar CoNi-MOFs, lamellar CoNi-MOF-3 with the minimum thickness exhibits an optimal electrochemical sensing performance toward hydrogen sulfide, with a sensitivity of 119.3 μA·mM-1·cm-2 in the linear range of 2-2000 μM. This study pioneers a new approach to the controlled construction and electrochemical activity modification of lamellar MOF materials.

P3MOT-decorated metal-porphyrin-based zirconium-MOF for the efficient electrochemical detection of 4-nitrobenzaldehyde

A novel hybrid composite integrating conductive poly-3-methoxythiophene and PCN-222(Fe) (porphyrin-metal-organic frameworks) was synthesized using an in situ polymerization strategy. Leveraging the large specific area of MOFs and the low electrical resistance of conductive polymers, the modified electrode proved to be a promising candidate for the electrochemical detection of 4-nitrobenzaldehyde. The electrocatalytic response was measured using differential pulse voltammetry techniques and cyclic voltammetry, where the linear concentration range of analyte detection was estimated to be 0-900 μM and the detection limit was 0.233 μM with high selectivity toward the analyte. The sensor demonstrated repeatability and stability, allowing the direct electroanalytical measurement of 4-nitrobenzaldehyde in real samples with reliable recovery. This methodology expands the application of porphyrin MOFs for the electroanalytical sensing of environmental contaminants.

Nanozyme-Enhanced Electrochemical Biosensors: Mechanisms and Applications

Nanozymes, as innovative materials, have demonstrated remarkable potential in the field of electrochemical biosensors. This article provides an overview of the mechanisms and extensive practical applications of nanozymes in electrochemical biosensors. First, the definition and characteristics of nanozymes are introduced, emphasizing their significant role in constructing efficient sensors. Subsequently, several common categories of nanozyme materials are delved into, including metal-based, carbon-based, metal-organic framework, and layered double hydroxide nanostructures, discussing their applications in electrochemical biosensors. Regarding their mechanisms, two key roles of nanozymes are particularly focused in electrochemical biosensors: selective enhancement and signal amplification, which crucially support the enhancement of sensor performance. In terms of practical applications, the widespread use of nanozyme-based electrochemical biosensors are showcased in various domains. From detecting biomolecules, pollutants, nucleic acids, proteins, to cells, providing robust means for high-sensitivity detection. Furthermore, insights into the future development of nanozyme-based electrochemical biosensors is provided, encompassing improvements and optimizations of nanozyme materials, innovative sensor design and integration, and the expansion of application fields through interdisciplinary collaboration. In conclusion, this article systematically presents the mechanisms and applications of nanozymes in electrochemical biosensors, offering valuable references and prospects for research and development in this field.

A Single Set of Well-Designed Aptamer Probes for Reliable On-site Qualitative and Ultra-Sensitive Quantitative Detection

Aptamer-based probes are pivotal components in various sensing strategies, owing to their exceptional specificity and versatile programmable structure. Nevertheless, numerous aptamer-based probes usually offer only a single function, limiting their capacity to meet the diverse requirements of multi-faceted sensing systems. Here, we introduced supersandwich DNA probes (SSW-DNA), designed and modified on the outer surface of nanochannels with hydrophobic inner walls, enabling dual functionality: qualitative detection for on-site analysis and quantitative detection for precise analysis. The fragmented DNAs resulting from the target recognition, are subsequently identified through lateral flow assays, enabling robust on-site qualitative detection of microcystin-LR with an impressively low limit of detection (LOD) at 0.01 μg/L. Meanwhile, the nanochannels enable highly sensitive quantification of microcystin-LR through the current analysis, achieving an exceptionally low LOD at 2.5×10-7  μg/L, with a broad dynamic range spanning from 1×10-6 to 1×102  μg/L. Furthermore, the process of target recognition introduces just a single potential error propagation, which reduces the overall risk of errors during the entire qualitative and quantitative detection process. This sensing strategy broadens the scope of applications for aptamer-based composite probes, holding promising implications across diverse fields, such as medical diagnosis, food safety, and environmental protection.

Construction of porphyrinic manganese-organic frameworks based on structural regulation for electrochemical determination of nitrobenzene in water and vegetable samples

Nitrobenzene (NB) is one of the major organic pollutants that has seriously endangered human health and the environment even in trace amounts. Therefore, it is of great significance to detect trace NB efficiently and sensitively. Herein, a porphyrinic metal-organic framework (MOF) of Mn-PCN-222 (PCN, porous coordination network) was first synthesized by the coordination between Zr6 cluster and tetrakis (4-carboxyphenyl)-porphyrin-Mn (Ⅲ) (MnTCPPCl) ligand. To regulate its structure and the electrochemical properties, a phenyl group was inserted in each branched chain of TCPP to form the TCBPP organic ligand. Then, we used Zr6 clusters and manganese metalloporphyrin (MnTCBPPCl) to synthesize a new porphyrin-based MOF (Mn-CPM-99, CPM, crystalline porous material). Due to the extended chains of TCPP, the rod-shaped structure of Mn-PCN-222 was switched to concave quadrangular bipyramid of Mn-CPM-99. Mn-CPM-99 exhibited higher porosity, larger specific surface area, better electrochemical performances than those of Mn-PCN-222. By using modular assembly technique, Mn-CPM-99 film was sequentially assembled on the surface of indium-tin-oxide (ITO) to prepare an electrochemical sensor (Mn-CPM-99/ITO). The proposed sensor showed excellent electrochemical reduction of NB and displayed three linear response ranges in the wide concentration ranges. The obtained low limit of detection (LOD, 1.3 nM), high sensitivity and selectivity, and good reproducibility of the sensor for NB detection fully illustrate that Mn-CPM-99 is an excellent candidate for electrochemical sensor interface material. Moreover, the sensor was successfully applied to the detection of NB in lake water and vegetable samples showing satisfactory recovery of 98.9%-101.8%.

AI-assisted mass spectrometry imaging with in situ image segmentation for subcellular metabolomics analysis

Subcellular metabolomics analysis is crucial for understanding intracellular heterogeneity and accurate drug-cell interactions. Unfortunately, the ultra-small size and complex microenvironment inside the cell pose a great challenge to achieving this goal. To address this challenge, we propose an artificial intelligence-assisted subcellular mass spectrometry imaging (AI-SMSI) strategy with in situ image segmentation. Based on the nanometer-resolution MSI technique, the protonated guanine and threonine ions were respectively employed as the nucleus and cytoplasmic markers to complete image segmentation at the subcellular level, avoiding mutual interference of signals from various compartments in the cell. With advanced AI models, the metabolites within the different regions could be further integrated and profiled. Through this method, we decrypted the distinct action mechanism of isomeric drugs, doxorubicin (DOX) and epirubicin (EPI), only with a stereochemical inversion at C-4'. Within the cytoplasmic region, fifteen specific metabolites were discovered as biomarkers for distinguishing the drug action difference between DOX and EPI. Moreover, we identified that the downregulations of glutamate and aspartate in the malate-aspartate shuttle pathway may contribute to the higher paratoxicity of DOX. Our current AI-SMSI approach has promising applications for subcellular metabolomics analysis and thus opens new opportunities to further explore drug-cell specific interactions for the long-term pursuit of precision medicine.

Coupling metal organic frameworks nanozyme with carbon nanotubes on the gradient porous hollow fiber membrane for nonenzymatic electrochemical H2O2 detection

In this paper, we present a gradient porous hollow fiber structure integrated the signal transduction within a microspace, serving as a platform for cellular metabolism monitoring. We developed a nonenzymatic electrochemical electrode by coupling carbon nanotubes (CNT) and metal organic frameworks (MOF) nanozyme on three-dimensional (3D) gradient porous hollow fiber membrane (GPF) for in-situ detection of cell released hydrogen peroxide (H2O2). The GPF was used as a substrate for cell culture as well as the supporting matrix of the working electrode. The ultrasonically coupled CNT@MOF composite was immobilized on the outer surface of the GPF by means of pressure filtration. Notably, the MOF, acting as a peroxidase mimic, exhibits superior stability compared to traditional horseradish peroxidase. The incorporation of CNT not only provided sufficient specific surface area to improve the uniform distribution of MOF nanozyme, but also formed 3D conductive network. This network efficiently facilitates the electrons transfer during the catalytic process of the MOF, addressing the inherent poor conductivity of MOFs. The GPF-CNT@MOF nonenzymatic bioelectrode demonstrated excellent electrocatalytic performance including rapid response, satisfactory sensing selectivity, and attractive stability, which enabled the development of a robust in-situ cellular metabolic monitoring platform.

Intelligent Identification of Cerebrospinal Fluid for the Diagnosis of Parkinson's Disease

Cerebrospinal fluid (CSF) biomarkers are more sensitive than the Movement Disorder Society (MDS) criteria for detecting prodromal Parkinson's disease (PD). Early detection of PD provides the best chance for successful implementation of disease-modifying treatments, making it crucial to effectively identify CSF extracted from PD patients or normal individuals. In this study, an intelligent sensor array was built by using three metal-organic frameworks (MOFs) that exhibited varying catalytic kinetics after reacting with potential protein markers. Machine learning algorithms were used to process fingerprint response patterns, allowing for qualitative and quantitative assessment of the proteins. The results were robust and capable of discriminating between PD and non-PD patients via CSF detection. The k-nearest neighbor regression algorithm was used to predict MDS scores with a minimum mean square error of 38.88. The intelligent MOF sensor array is expected to promote the detection of CSF biomarkers due to its ability to identify multiple targets and could be used in conjunction with MDS criteria and other techniques to diagnose PD more sensitively and selectively.

A Triptycene-Based Layered/Flower-Like 2D Conductive Metal-Organic Framework with 3D Extension as an Electrode for Efficient Li Storage

2D metal-organic frameworks (2D MOFs) with π conjugation have attracted widespread attention in the field of lithium storage due to their unique electron transfer units and structural characteristics. However, the periodic 2D planar extension structure hides some active sites, which is not conducive to the utilization of its structural advantages. In this work, a series of triptycene-based 2D conductive MOFs (M-DBH, M = Ni, Mn, and Co) with 3D extension structures are constructed by coordinating 9,10-dihydro-9,10-[1,2]benzenoanthracene-2,3,6,7,14,15-hexaol with metal ions to explore their potential applications in lithium-ion and lithium-sulfur batteries. This is the first study in which 2D conductive MOFs with the 3D extended molecule are used as electrode materials for lithium storage. The designed material generates rich active sites through staggered stacking layers and shows excellent performance in lithium-ion and lithium-sulfur batteries. The capacity retention rate of Ni-DBH can reach over 70% after 500 cycles at 0.2 C in lithium-ion batteries, while the capacity of S@Mn-DBH exceeds 305 mAh g-1 after 480 cycles at 0.5 C in lithium-sulfur batteries. Compared with the materials with 2D planar extended structures, the M-DBH electrodes with 3D extended structures in this work exhibit better performance in terms of cycle time and lithium storage capacity.

A Recent Advancement in Food Quality Assessment: Using MOF-Based Sensors: Challenges and Future Aspects

Monitoring food safety is crucial and significantly impacts the ecosystem and human health. To adequately address food safety problems, a collaborative effort needed from government, industry, and consumers. Modern sensing technologies with outstanding performance are needed to meet the growing demands for quick and accurate food safety monitoring. Recently, emerging sensors for regulating food safety have been extensively explored. Along with the development in sensing technology, the metal-organic frameworks (MOF)-based sensors gained more attention due to their excellent sensing, catalytic, and adsorption properties. This review summarizes the current advancements and applications of MOFs-based sensors, including colorimetric, electrochemical, luminescent, surface-enhanced Raman scattering, and electrochemiluminescent sensors. and also focused on the applications of MOF-based sensors for the monitoring of toxins such as heavy metals, pesticide residues, mycotoxins, pathogens, and illegal food additives from food samples. Future trends, as well as current developments in MOF-based materials.

Detection of gallic acid in food using an ultra-sensitive electrochemical sensor based on glass carbon electrode modified by bimetal doped carbon nanopolyhedras

Gallic acid is widely used as an antioxidant in food because of its good antioxidant function, but excessive intake induces side effects in humans, so it is essential to devise a highly responsive technique for detecting gallic acid. In this work, we synthesized ZIF-67@FePc by the one-pot method. The synthesized material is more stable at high temperatures compared to ZIF-67 and maintains its original morphology during pyrolysis, when iron was introduced as a second metal active site during the synthesis process. Subsequently, Co/FeOX@NC-800 was employed to fabricate a GA sensor on a GCE. The developed sensor exhibited remarkable sensitivity towards GA, featuring a low LOD of 1.30 nM and a linear range spanning from 5 to 4500 nM. The electrochemical sensors we have prepared also showed good selectivity, stability, and reproducibility. It has been successfully employed for detecting GA in actual samples such as apples, grapes, tomatoes, and red wine.

A proof-of-concept electroreduction-free anodic stripping voltammetry analysis of Ag(I) based on S,N-Ti3C2Tx MXene nanoribbons

Herein, by preparing sulfur and nitrogen co-doped Ti3C2Tx MXene nanoribbons (S,N-Ti3C2TxR) as a sensing material, a sensitive and novel electroreduction-free anodic stripping voltammetry strategy was designed to detect Ag(I) (Ag+) for the first time, which can successfully avoid the power-consuming electroreduction step, achieving simple, sensitive and efficient detection for Ag+ with a low detection limit and wide linearity.

Metalloporphyrin-Based Metal-Organic Frameworks for the Ultrasensitive Chemiresistive Detection of NO2: Effect of the Central Metal on Tuning the Sensing Performance

The highly sensitive and selective detection of trace hazardous gases at room temperature is very promising for health protection and environmental safety. Herein, chemiresistive sensors for NO2 were fabricated based on self-assembled films of the four metalloporphyrin (MPor)-based metal-organic frameworks PCN-222-M (M = Cu, Ni, Co, Fe) by the quasi-Langmuir-Shäfer method. It is found that the relative responses of the four PCN-222-M films are linearly related to the NO2 concentration, and the PCN-222-Cu possessed an unprecedented high response to NO2 with a sensitivity of 2209% ppm-1 in the 4-20 ppb range and a low limit of detection (LOD) of 0.93 ppb, achieving the best performance reported so far for NO2 detection at room temperature. Meanwhile, PCN-222-Ni showed the fastest recovery among the four PCN-222-M films, which can be used for the rapid detection of NO2. Excellent reproducibility, stability, selectivity, and moisture resistance are shown for both PCN-222-Cu and PCN-222-Ni. Combining the experimental study and density functional theory (DFT) calculation, the essential roles of MPor units and the MPor/Zr6 cluster hybrid material in tuning the Fermi level and the electron transfer between PCN-222-M and NO2 were further proved. These were less considered topics in previous studies on MOFs. This work explores the application of MPor-based MOFs in gas sensing by selecting appropriate MPor units, thus providing guidance for the development of MOF-based chemiresistive sensors.

A non-enzymatic glucose sensor based on a mesoporous carbon sphere immobilized Co-MOF-74 nanocomposite

Exploration of credible non-enzymatic glucose sensors with high selectivity and sensitivity is of great significance for early clinical monitoring of glucose concentration and preventing the threat of diabetes to human health. Here, mesoporous carbon (MC) sphere immobilized Co-MOF-74 nanorods (NRs), denoted as Co-MOF-74 NRs/MC, were successfully prepared, in which the nanostructural porous carbon sphere was obtained using cobalt glycolate as the built-in template followed by a subsequent carbonization and acid treatment, and the MC spheres were then in situ deposited on the surface of Co-MOF-74 NRs via a solvothermal method. Benefiting from the good conductivity of the grafted porous carbon spheres and the abundant active sites, as well as the permeability of microporous MOF-74 nanocrystals, the Co-MOF-74 NRs/MC modified glassy carbon electrode (GCE) exhibited effective non-enzymatic glucose sensing performance with a fast response time (less than 3 s) and a glucose sensitivity of 98.0 μA cm-2 mM-1. Furthermore, the Co-MOF-74 NRs/MC/GCE showed a favourable anti-interference capability in the presence of various interferents and good long-term reusability. The applicability of Co-MOF-74 NRs/MC/GCE for glucose sensing in real serum samples was also investigated, verifying the applicability of the electrode for targeted glucose monitoring in practical applications.

Visible-light-induced photocatalytic CO2 reduction over zirconium metal organic frameworks modified with different functional groups

The reduction of CO₂ into high value-added chemicals and fuels by a photocatalytic technology can relieve energy shortages and the environmental problems caused by greenhouse effects. In the current work, an amino-functionalized zirconium metal organic framework (Zr-MOF) was covalently modified with different functional groups via the condensation of Zr-MOF with 2-pyridinecarboxaldehyde (PA), salicylaldehyde (SA), benzaldehyde (BA), and trifluoroacetic acid (TA), named Zr-MOF-X (X = PA, SA, BA, and TA), respectively, through the post-synthesis modification. Compared with Zr-MOF and Zr-MOF-TA, the introduction of PA, SA, or BA into the framework of Zr-MOF can not only enhance the visible-light harvesting and CO₂ capture, but also accelerate the photogenerated charge separation and transfer, thereby improving the photocatalytic ability of Zr-MOF for CO₂ reduction. These results indicate that the modification of Zr-MOF with electron-donating groups can promote the photocatalytic CO₂ reduction. Therefore, the current work provides an instructive approach to improve the photocatalytic efficiency of CO₂ reduction through the covalent modification of MOFs.

Platform-agnostic electrochemical sensing app and companion potentiostat

Electrochemical sensing is ubiquitous in a number of fields ranging from biosensing, to environmental monitoring through to food safety and battery or corrosion characterisation. Whereas conventional potentiostats are ideal to develop assays in laboratory settings, they are in general, not well-suited for field work due to their size and power requirements. To address this need, a number of portable battery-operated potentiostats have been proposed over the years. However, most open source solutions do not take full advantage of integrated circuit (IC) potentiostats, a rapidly evolving field. This is partly due to the constraining requirements inherent to the development of dedicated interfaces, such as apps, to address and control a set of common electrochemical sensing parameters. Here we propose the PocketEC, a universal app that has all the functionalities to interface with potentiostat ICs through a user defined property file. The versatility of PocketEC, developed with an assay developer mindset, was demonstrated by interfacing it, via Bluetooth, to the ADuCM355 evaluation board, the open-source DStat potentiostat and the Voyager board, a custom-built, small footprint potentiostat based around the LMP91000 chip. The Voyager board is presented here for the first time. Data obtained using a standard redox probe, Ferrocene Carboxylic Acid (FCA) and a silver ion assay using anodic stripping multi-step amperometry were in good agreement with analogous measurements using a bench top potentiostat. Combined with its Voyager board companion, the PocketEC app can be used directly for a number of wearable or portable electrochemical sensing applications. Importantly, the versatility of the app makes it a candidate of choice for the development of future portable potentiostats. Finally, the app is available to download on the Google Play store and the source codes and design files for the PocketEC app and the Voyager board are shared via Creative Commons license (CC BY-NC 3.0) to promote the development of novel portable or wearable applications based on electrochemical sensing.

Two-Dimensional Conductive Metal-Organic Framework for Small-Molecule Sensing in Aqueous Solution

Two-dimensional (2D) conductive metal-organic frameworks (cMOFs) have emerged as powerful transducers for electrochemical sensing. However, electrochemical sensing in aqueous solutions remains at a very early stage for 2D cMOFs. Herein, the interfacial capacitances of a 2D cMOF are utilized for electrochemical sensing for the first time. Various redox-innocent compounds along with redox-active compounds in aqueous solutions are successfully detected based on the responses of two capacitance peaks at low voltages. The quantitative sensitivity to ascorbic acid is even an order of magnitude higher than the previous voltammetric method. Further investigation demonstrates that the responses are rooted in the pseudocapacitances of the 2D cMOF, i.e., the transitions among the multiple redox states of the ligands. The analytes are suggested to alert the d-p conjugation and exchange electrons with the 2D cMOF. These deep insights in response mechanisms represent an important step for promoting the application of 2D cMOFs in chemical sensing.

Induced Production of Atypical Naturally Nonpreferred Metal-Organic Frameworks and Their Detachment via Provoking Post-Mismatching

The structures of metal-organic frameworks (MOFs) are typically determined by the building blocks that compose them and the conditions under which they are formed. MOFs tend to adopt a thermodynamically and/or kinetically stable structure (naturally preferred form). Thus, constructing MOFs with naturally nonpreferred structures is a challenging task, as it requires avoiding the easier pathway toward a naturally preferred MOF. Herein, an approach to construct naturally nonpreferred dicarboxylate-linked MOFs employing reaction templates is reported. This strategy relies on the registry between the surface of the template and the cell lattice of a target MOF, which reduces the effort required to form naturally nonpreferred MOFs. Reactions of p-block trivalent metal ions (Ga3+ and In3+ ) with dicarboxylic acids typically produce preferred MIL-53 or MIL-68. However, the surface of UiO-67 (and UiO-66) template exhibits the well-defined hexagonal lattice, which induce the selective formation of a naturally nonpreferred MIL-88 structure. Inductively grown MIL-88s are purely isolated from the template via provoking a post-mismatch in their lattices and weakening the interfacial interaction between product and template. It is also discovered that an appropriate template for effective induced production of naturally nonpreferred MOFs shall be properly selected based on the cell lattice of a target MOF.

Room Temperature Synthesis Mediated Porphyrinic NanoMOF Enables Benchmark Electrochemical Biosensing

Leveraging size effects, nanoparticles of metal-organic frameworks, nanoMOFs, have recently gained traction, amplifying their scopes in electrochemical sensing. However, their synthesis, especially under eco-friendly ambient conditions remains an unmet challenge. Herein, an ambient and fast secondary building unit (SBU)-assisted synthesis (SAS) route to afford a prototypal porphyrinic MOF, Fe-MOF-525 is introduced. Albeit the benign room temperature conditions, Fe-MOF-525(SAS) nanocrystallites obtained are of ≈30 nm size, relatively smaller than the ones conventional solvothermal methods elicit. Integrating Fe-MOF-525(SAS) as a thin film on a conductive indium tin oxide (ITO) surface affords Fe-MOF-525(SAS)/ITO, an electrochemical biosensor. Synergistic confluence of modular MOF composition, analyte-specific redox metalloporphyrin sites, and crystal downsizing contribute to its benchmark voltammetric uric acid (UA) sensing. Showcasing a wide linear range of UA detection with high sensitivity and low detection limit, this SAS strategy coalesces ambient condition synthesis and nanoparticle size control, paving a green way to advanced sensors.

Mn-MOF catalyzed multi-site atom transfer radical polymerization electrochemical sensing of miRNA-21

A green electrochemical biosensor was developed based on metal-organic framework (MOF)-catalyzed atom transfer radical polymerization (ATRP) for quantifying miRNA-21, used as the proof-of-concept analyte. Unlike conventional ATRP, Mn-PCN-222 (PCN, porous coordination network) could be used as an alternative for green catalyst to substitute traditional catalysts. First, poly (diallyldimethylammonium chloride) (PDDA) was fixed on the surface of the indium tin oxide (ITO) electrode, and then the Mn-PCN-222 was linked to ITO electrode via electrostatic binding with PDDA. Next, aminated ssDNA (NH₂-DNA) was used to modify the electrode further by amide reaction with Mn-PCN-222. Then, the recognition and hybridization of NH₂-DNA with miRNA-21 prompt the generation of DNA-RNA complexes, which further hybridize with Fc-DNA@β-CD-Br₁₅ and permit the initiator to be immobilized on the electrode surface. Accordingly, β-CD-Br₁₅ could initiate the polymerization of ferrocenylmethyl methacrylates (FcMMA) under the catalysis of MOF to complete the ATRP reaction. FcMMA presented a distinct electrochemical signal at ~ 0.33 V. Taking advantage of the unique multi-site properties of β-CD-Br₁₅ and the efficient catalytic reaction induced by Mn-PCN-222, ultrasensitive detection of miRNA-21 was achieved with a detection limit of 0.4 fM. The proposed electrochemical biosensor has been applied to the detection of miRNA-21 in serum samples. Therefore, the proposed strategy exhibited potential in early clinical biomedicine.

Metal-organic frameworks (MOFs) based luminescent and electrochemical sensors for food contaminant detection

With the increasing population, food toxicity has become a prevalent concern due to the growing contaminants of food products. Therefore, the need for new materials for toxicant detection and food quality monitoring will always be in demand. Metal-organic frameworks (MOFs) based on luminescence and electrochemical sensors with tunable porosity and active surface area are promising materials for food contaminants monitoring. This review summarizes and studies the most recent progress on MOF sensors for detecting food contaminants such as pesticides, antibiotics, toxins, biomolecules, and ionic species. First, with the introduction of MOFs, food contaminants and materials for toxicants detection are discussed. Then the insights into the MOFs as emerging materials for sensing applications with luminescent and electrochemical properties, signal changes, and sensing mechanisms are discussed. Next, recent advances in luminescent and electrochemical MOFs food sensors and their sensitivity, selectivity, and capacities for common food toxicants are summarized. Further, the challenges and outlooks are discussed for providing a new pathway for MOF food contaminant detection tools. Overall, a timely source of information on advanced MOF materials provides materials for next-generation food sensors.

Fundamental Perspectives on the Electrochemical Water Applications of Metal-Organic Frameworks

HIGHLIGHTS

The recent development and implementation of metal-organic frameworks (MOFs) and MOF-based materials in electrochemical water applications are reviewed. The critical factors that affect the performances of MOFs in the electrochemical reactions, sensing, and separations are highlighted. Advanced tools, such as pair distribution function analysis, are playing critical roles in unraveling the functioning mechanisms, including local structures and nanoconfined interactions. Metal-organic frameworks (MOFs), a family of highly porous materials possessing huge surface areas and feasible chemical tunability, are emerging as critical functional materials to solve the growing challenges associated with energy-water systems, such as water scarcity issues. In this contribution, the roles of MOFs are highlighted in electrochemical-based water applications (i.e., reactions, sensing, and separations), where MOF-based functional materials exhibit outstanding performances in detecting/removing pollutants, recovering resources, and harvesting energies from different water sources. Compared with the pristine MOFs, the efficiency and/or selectivity can be further enhanced via rational structural modulation of MOFs (e.g., partial metal substitution) or integration of MOFs with other functional materials (e.g., metal clusters and reduced graphene oxide). Several key factors/properties that affect the performances of MOF-based materials are also reviewed, including electronic structures, nanoconfined effects, stability, conductivity, and atomic structures. The advancement in the fundamental understanding of these key factors is expected to shed light on the functioning mechanisms of MOFs (e.g., charge transfer pathways and guest-host interactions), which will subsequently accelerate the integration of precisely designed MOFs into electrochemical architectures to achieve highly effective water remediation with optimized selectivity and long-term stability.

3D Lanthanide Neodymium Porphyrin Metal-Organic Framework for Photocatalytic Oxidation of Styrene

A novel three-dimensional lanthanide porphyrin-based MOF (Nd-PMOFs) was synthesized by using tetracarboxyphenyl porphyrin as the ligand and the lanthanide Nd as the coordination metal. Its specific crystal structure information was obtained by single-crystal diffraction with the space group C2/c and the empirical formula C₇₂H₄₅N₆Nd₂O_15.25. This new Nd porphyrin-based MOF with an organic framework formed by a unique coordination method enables the effective separation of photogenerated electrons and holes under photoluminescence, giving it excellent photocatalytic property which could be verified by the characterization data. The photocatalytic performance was examined by taking tert-butyl hydroperoxide as the oxidant and Nd-PMOFs as the catalyst for photocatalytic oxidation of styrene to benzaldehyde with 91.4% conversion and 81.2% benzaldehyde selectivity under optimal reactions, which surpasses most of the results reported in the literature. Several styrenes with other substituents were screened to explore the general applicability of Nd-PMOF for photocatalysis of styrene, among which Nd-PMOFs also exhibited excellent photocatalytic performance. This work offers the possibility to apply lanthanide organometallic frameworks, which are widely used in fluorescent materials, to photocatalysis. In addition, it also provides a new method for the catalytic generation of benzaldehyde from styrene that is consistent with the needs of modern green development.

A Ni-MOF as Fluorescent/Electrochemical Dual Probe for Ultrasensitive Detection of Picric Acid from Aqueous Media

A water-stable, microporous, luminescent Ni(II)-based metal-organic framework (MOF) (Ni-OBA-Bpy-18) with a 4-c uninodal sql topology was solvothermally synthesized using mixed N-, O-donor-directed π-conjugated co-ligands. The extraordinary performance of this MOF toward rapid monitoring of mutagenic explosive trinitrophenol (TNP) in aqueous and vapor phases by the fluorescence "Turn-off" technique with an ultralow detection limit of 66.43 ppb (K_sv: 3.45 × 10⁵ M^-1) was governed by a synchronous occurrence of photoinduced electron transfer-resonance energy transfer-intermolecular charge transfer (PET-RET-ICT) and non-covalent π···π weak interactions, as revealed from density functional theory studies. The recyclable nature of the MOF, detection from complex environmental matrices, and fabrication of a handy MOF@cotton-swab detection kit certainly escalated the on-field viability of the probe. Interestingly, the presence of electron-withdrawing TNP decisively facilitated the redox events of the reversible Ni^III/II and Ni^IV/III couples under an applied voltage based on which electrochemical recognition of TNP was realized by the Ni-OBA-Bpy-18 MOF/glassy carbon electrode, with an excellent detection limit of ∼0.6 ppm. Such detection of a specific analyte by MOF-based probe via two divergent yet coherent techniques is unprecedented and yet to be explored in relevant literature.

Enzymatic bionanocatalysts for combating peri-implant biofilm infections by specific heat-amplified chemodynamic therapy and innate immunomodulation

Bacterial biofilm-associated infection is a life-threatening emergency contributing from drug resistance and immune escape. Herein, a novel non-antibiotic strategy based on the synergy of bionanocatalysts-driven heat-amplified chemodynamic therapy (CDT) and innate immunomodulation is proposed for specific biofilm elimination by the smart design of a biofilm microenvironment (BME)-responsive double-layered metal-organic framework (MOF) bionanocatalysts (MACG) composed of MIL-100 and CuBTC. Once reaching the acidic BME, the acidity-triggered degradation of CuBTC allows the sequential release of glucose oxidase (GOx) and an activable photothermal agent, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). GOx converts glucose into H₂O₂ and gluconic acid, which can further acidify the BME to accelerate the CuBTC degradation and GOx/ABTS release. The in vitro and in vivo results show that horseradish peroxidase (HRP)-mimicking MIL-100 in the presence of self-supplied H₂O₂ can catalyze the oxidation of ABTS into oxABTS to yield a photothermal effect that breaks the biofilm structure via eDNA damage. Simultaneously, the Cu ion released from the degraded CuBTC can deplete glutathione and catalyze the splitting of H₂O₂ into •OH, which can effectively penetrate the heat-induced loose biofilms and kill sessile bacteria (up to 98.64%), such as E. coli and MRSA. Particularly, MACG-stimulated M1-macrophage polarization suppresses the biofilm regeneration by secreting pro-inflammatory cytokines (e.g., IL-6, TNF-α, etc.) and forming a continuous pro-inflammatory microenvironment in peri-implant biofilm infection animals for at least 14 days. Such BME-responsive strategy has the promise to precisely eliminate refractory peri-implant biofilm infections with extremely few adverse effects.

Metal-Organic Framework-Based Colloidal Particle Synthesis, Assembly, and Application

Metal-organic frameworks (MOFs) assembled from metal nodes and organic ligands have received significant attention over the past two decades for their fascinating porous properties and broad applications. Colloidal MOFs (CMOFs) not only inherit the intrinsic properties of MOFs, but can also serve as building blocks for self-assembly to make functional materials. Compared to bulk MOFs, the colloidal size of CMOFs facilitates further manipulation of CMOF particles in a single or collective state in a liquid medium. The resulting crystalline order obtained by self-assembly in position and orientation can effectively improve performance. In this review, we summarize the latest developments of CMOFs in synthesis strategies, self-assembly methods, and related applications. Finally, we discuss future challenges and opportunities of CMOFs in synthesis and assembly, by which we hope that CMOFs can be further developed into new areas for a wider range of applications.

MXene-Derived Metal-Organic Framework@MXene Heterostructures toward Electrochemical NO Sensing

The electrochemical sensing of nitric oxide (NO) molecules by metal-organic framework (MOF) catalysts has been impeded, to a large extent, owing to their poor electrical conductivity and weak NO adsorption. In this work, incomplete in situ conversion of V₂ CT_x (T = terminal atoms) MXene to MOF is adopted, forming MOF@MXene heterostructures, which outperform MXene and MOF monocomponents toward electrochemical NO sensing. Density functional theory (DFT) calculation results indicate metal-like electronic characters for the heterostructure benefiting from the dominating contribution of the V 3d orbitals of the metallic MXene. Moreover, plane-averaged charge density difference shows substantial charge redistribution occurs at the heterointerfaces, producing a built-in field, which facilitates charge transfer. Besides, molecular mechanics-based simulated annealing calculation reveals greatly enhanced adsorption energies of NO molecules on the heterointerfaces than that on separate MOFs and MXenes. Hence, the facilitated charge transfer and preferential NO adsorption are responsible for the dramatically promoted performance toward NO sensing. The prudent design of MOF@MXene heterostructure may spur advanced electrocatalysts for electrochemical sensing.

2D Conductive Covalent Organic Frameworks with Abundant Carbonyl Groups for Electrochemical Sensing

Due to their permanent porosity, robust chemical stability, and tunable structure, covalent organic frameworks (COFs) are very attractive in the application of energy storage, catalysis, sorption, and sensing. However, the very low conductivity of COFs severely restricts their application in electrochemical sensing. Here, an aza-fused π-conjugated COFs with abundant carbonyl groups (COF1) was synthesized and deployed as electrode materials in electrochemical sensing for the first time. The current response of the acetylcholinesterase biosensor based on COF1 increases three times when compared to the electrode without COF1. The effects of carbonyl groups on signal enhancement were proved in depth by a series of characterization and comparison experiments with the prepared COF2 without carbonyl groups. The results demonstrated that exposed carbonyl active sites of COF1 can promote the effective immobilization and bioactivity preserving of enzyme molecules and contribute to the enrichment of analytes. Together with the good conductivity of COF1 derived from a fully extended 2D aromatized π-conjugated system, all of which improve the biosensor performance. The COF1-based biosensor exhibited fast response speed, high sensitivity, good selectivity and practicability, and robust stability for organophosphorus pesticide detection and proved to be a promising tool for the rapid and onsite detection of organophosphorus pesticides in the environment.

A Portable Electrochemical Sensor Based on Manganese Porphyrin-Functionalized Carbon Cloth for Highly Sensitive Detection of Nitroaromatics and Gaseous Phenol

Organic pollutants (OPs) have garnered a considerable amount of attention in recent times due to their extreme toxicity toward humans and the ecosystem. The need for an inexpensive yet robust, sensitive, selective, and easy-to-operate method for detecting OPs remains a challenge. Herein, a portable electrochemical sensor is proposed based on manganese porphyrin-functionalized carbon cloth (CC). To explain the electrochemical performance of the sensor, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed. The presence of manganese(III) ion in the center of the porphyrin ligand acted as an agent for the transfer of electrons and enhanced sensitivity toward analyte-specific redox catalysis. Moreover, it allowed for the concurrent detection of multiple analytes in a complex environment. The modified CC electrode can selectively detect nitroaromatic and phenolic compounds with accessible data collected through wireless means onto a smartphone device. The as-synthesized electrode demonstrated a higher sensitivity toward the detection of nitrobenzene (NB) and aqueous phenol with a limit of detection (LOD) found to be 5.9268 × 10^-10 M and 4.0178 × 10^-10 M, respectively. Additionally, our proposed portable electrochemical sensor demonstrates a high selectivity and reproducibility toward nitroaromatic and phenolic compounds, which can be employed in real complex water samples. With regard to the sensor's remarkable electrochemical performance, it is envisaged that such a sensor could pave the way for environmental point of care (POC) testing.

Ultrathin Graphdiyne/Graphene Heterostructure as a Robust Electrochemical Sensing Platform

Graphdiyne (GDY) has been considered as an appealing electrode material for electrochemical sensing because of its alkyne-rich structure and high degrees of π-conjugation, which shows great affinity to heavy metal ions and pollutant molecules via d-π and π-π interactions. However, the low surface area and poor conductivity of bulk GDY limit its electrochemical performance. Herein, a two-dimensional ultrathin GDY/graphene (GDY/G) nanostructure was synthesized and used as an electrode material for electrochemical sensing. Graphene plays the role of an epitaxy template for few-layered GDY growth and conductive layers. The formed few-layered GDY with a high surface area possesses abundant affinity sites toward heavy metal ions (Cd²⁺, Pb²⁺) and toxic molecules, for example, nitrobenzene and 4-nitrophenol, via d-π and π-π interactions, respectively. Moreover, hemin as a key part of the enzyme catalytic motif was immobilized on GDY/G via π-π interactions. The artificial enzyme mimic hemin/GDY/G-modified electrode exhibited promising ascorbic acid and uric acid detection performance with excellent sensitivity and selectivity, a good linear range, and reproducibility. More importantly, real sample detection and the feasibility of this electrochemical sensor as a wearable biosensor were demonstrated.

Design and Application of Electrochemical Sensors with Metal-Organic Frameworks as the Electrode Materials or Signal Tags

Metal-organic frameworks (MOFs) with fascinating chemical and physical properties have attracted immense interest from researchers regarding the construction of electrochemical sensors. In this work, we review the most recent advancements of MOF-based electrochemical sensors for the detection of electroactive small molecules and biological macromolecules (e.g., DNA, proteins, and enzymes). The types and functions of MOF-based nanomaterials in terms of the design of electrochemical sensors are also discussed. Furthermore, the limitations and challenges of MOF-based electrochemical sensing devices are explored. This work should be invaluable for the development of MOF-based advanced sensing platforms.

A dual-channel probe based on copper ion-mediated metal organic framework composite for colorimetric and ratiometric fluorescence monitoring of glyphosate degradation in soil and water

A dual-channel probe was developed, based on a novel composite metal organic frameworks (ZnMOF-74@Al-MOF) for glyphosate determination through ratio fluorescence and colorimetric methods. The prepared probe can not only recognize and combine glyphosate by introducing copper ion into the MOF, but also possess peroxidase-like catalytic activity. The recognition of target glyphosate brought about changes relative to its concentration on fluorescence intensity and ultraviolet absorption. And, the high specific surface area and porosity of porphyrin MOF provides the developed probe with more response opportunities to afford a better detection performance for glyphosate. Under optimum conditions, the copper ion-mediated method exhibited good detection performance for glyphosate with low detection limits (0.070 and 0.092 μg mL^-1 for fluorescence and colorimetric techniques, respectively). Furthermore, the possible mechanisms of the fluorescence quenching and the peroxidase-like catalytic of the probe were also explored. This dual-channel method was applied to monitor glyphosate degradation in environmental samples and satisfactory results were obtained.

Optimizing Photodetectors in Two-Dimensional Metal-Metalloporphyrinic Framework Thin Films

Two-dimensional (2D) metalloporphyrin-based MOF thin films possessing abundant π-π interactions are promising materials for photoelectronic devices, but no reports on fabrication of photodetectors are available so far. Herein, a series of 2D MOF Zn2[TCPP(M)] (named ZnTCPP(M); TCPP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin; M = Zn, Mn, Fe, and H2) films with [001] orientation are fabricated on SiO2/Si substrates by the liquid-phase epitaxial (LPE) layer-by-layer (lbl) approach and further assembled to photodetectors. The obtained ZnTCPP(M)-based photodetectors exhibit an excellent photoresponse due to abundant π-π stacking between the MOF layers. Moreover, the metalloporphyrinic groups in ZnTCPP(M) have a significant influence on modulating the photoresponse of the photodetectors, among which the prepared ZnTCPP(Zn) film-based device exhibits the best photodetection performance with a high on/off ratio of 2.3 × 104, responsivity (Rλ, up to 10.3 A W-1), short rise/fall times (0.09/0.07 s), and a large detectivity (D*) of 8.1 × 1013 Jones. Density functional theory (DFT) calculations reveal that the perturbation of the ring π-electron system and the introduction of low-lying states as well as the large delocalization of the metalloporphyrinic group will adjust the photodetection performance of ZnTCPP(M) films. These results will provide a new understanding of the modulation of 2D metalloporphyrinic MOFs toward photodetection performance and perspective for the fabrication of photoelectronic devices.

Electrochemical Detection of Dinitrobenzene on Silicon Electrodes: Toward Explosives Sensors

Detection of explosives is vital for protection and criminal investigations, and developing novel explosives’ sensors stands at the forefront of the analytical and forensic chemistry endeavors. Due to the presence of terminal nitro groups that can be electrochemically reduced, nitroaromatic compounds (NACs) have been an analytical target for explosives’ electrochemical sensors. Various electrode materials have been used to detect NACs in solution, including glassy carbon electrodes (GCE), platinum (Pt), and gold (Au) electrodes, by tracking the reversible oxidation/reduction properties of the NACs on these electrodes. Here, we show that the reduction of dinitrobenzene (DNB) on oxide-free silicon (Si–H) electrodes is irreversible with two reduction peaks that disappear within the successive voltammetric scanning. AFM imaging showed the formation of a polymeric film whose thickness scales up with the DNB concentration. This suggest that Si–H surfaces can serve as DNB sensors and possibly other explosive substances. Cyclic voltammetry (CV) measurements showed that the limit of detection (LoD) on Si–H is one order of magnitude lower than that obtained on GCE. In addition, EIS measurements showed that the LoD of DNB on Si–H is two orders of magnitude lower than the CV method. The fact that a Si–H surface can be used to track the presence of DNB makes it a suitable surface to be implemented as a sensing platform. To translate this concept into a sensor, however, it would require engineering and fabrication prospect to be compatible with the current semiconductor technologies.

Metal Centers and Organic Ligands Determine Electrochemistry of Metal-Organic Frameworks

The properties and applications of metal-organic frameworks (MOFs) can be tuned by their metal centers and organic ligands. To reveal experimentally and theoretically the influence of metal centers and ligands on electrochemical performance of MOFs, three MOFs with copper or zinc centers and organic ligands of 2-methylimidazole (2MI) or 1,3,5-benzenetricarboxylic acid (H₃ BTC) are synthesized and characterized in this study. 2D and porous Cu-2MI exhibits a larger active area, faster electron transfer capability, and stronger adsorption capacity than bulk Cu-BTC and dodecahedron Zn-2MI. Density functional theory calculations of adsorption ability of three MOFs toward xanthine (XA), hypoxanthine (HXA), and malachite green (MG) prove that 2D Cu-2MI has the strongest adsorption energies to three targets. Rotating disk electrode measurements reveal that 2D Cu-2MI features the biggest intrinsic heterogeneous rate constant toward three analytes. On 2D Cu-2MI sensitive and selective monitoring of XA, HXA, and MG is then achieved using differential pulse voltammetry. Their monitoring in real samples on 2D Cu-2MI is accurate and comparable with that using high-performance liquid chromatography. In summary, regulation of electrochemical sensing features of MOFs is realized through defining selected metal centers and organic ligands.

Cobalt Metal-Organic Frameworks with Aggregation-Induced Emission Characteristics for Fluorometric/Colorimetric Dual Channel Detection of Nitrogen-Rich Heterocyclic Compounds

Nitrogen-rich heterocyclic compounds (NRHCs) are an emerging type of explosive, and their quantification is important in national security inspection and environmental monitoring. Up until now, designing an efficient NRHCs sensing strategy was still in the early stages. Herein, a new metal-organic framework (MOF) with aggregation-induced emission (AIE) characteristics is synthesized with fluorometric/colorimetric responses for rapid and selective detection of NRHCs. The nonemissive probe is designed with tetraphenylethylene derivative as the linker and Co as the node, quencher, and color-changing agent. Cobalt AIE-MOF exhibits a turn-on emission enhancement due to the competitive coordination substitution between NRHCs and the scaffold as well as the following AIE process of the liberative linkers. Meanwhile, the color appearance of the probe changes from blue to yellow based on the dissociation of the original Co coordinating system. Using this dual-mode probe, single- and dual-ring NRHCs are successfully detected from 5 μM to 7.5 mM within 25 s. The cobalt AIE-MOF exhibits excellent selectivity of NRHCs against a variety of interferences, providing a promising tool for designing a multichannel detection strategy.

Stimuli-Modulated Metal Oxidation States in Photochromic MOFs

Tuning metal oxidation states in metal-organic framework (MOF) nodes by switching between two discrete linker photoisomers via an external stimulus was probed for the first time. On the examples of three novel photochromic copper-based frameworks, we demonstrated the capability of switching between +2 and +1 oxidation states, on demand. In addition to crystallographic methods used for material characterization, the role of the photochromic moieties for tuning the oxidation state was probed via conductivity measurements, cyclic voltammetry, and electron paramagnetic resonance, X-ray photoelectron, and diffuse reflectance spectroscopies. We confirmed the reversible photoswitching activity including photoisomerization rate determination of spiropyran- and diarylethene-containing linkers in extended frameworks, resulting in changes in metal oxidation states as a function of alternating excitation wavelengths. To elucidate the switching process between two states, the photoisomerization quantum yield of photochromic MOFs was determined for the first time. Overall, the introduced noninvasive concept of metal oxidation state modulation on the examples of stimuli-responsive MOFs foreshadows a new pathway for alternation of material properties toward targeted applications.

Coordination networks constructed from a flexible ligand: single-crystal-to-single-crystal transformations and thermoresponsive and electrochemical performances

This work reveals the relationships between the structures and redox/thermoresponsive/electrochemical performances of the new 2D coordination networks by single-crystal-to-single-crystal analysis and electrochemical measurements.

Functionalized MOF PCN-222-loaded quantum dots as an electrochemiluminescence sensing platform for the sensitive detection of p-nitrophenol

The composite PCN-222@CdSe was used to detect PNP.

A MOF Multifunctional Cargo Vehicle for Reactive Gas Delivery and Catalysis

Efficient delivery of reactive and toxic gaseous reagents to organic reactions was studied using metal-organic frameworks (MOFs). Simultaneous cargo vehicle and catalytic capabilities of several MOFs were probed for the first time using the examples of  aromatization, aminocarbonylation, and carbonylative Suzuki-Miyaura coupling reactions. These reactions highlight that MOFs can serve a dual role as a gas cargo vehicle and a catalyst,  leading to product formation with yields similar to reactions employing pure gases. Furthermore, the MOFs can be recycled without sacrificing product yield, while simultaneously maintaining crystallinity. The reported findings were supported crystallographically and spectroscopically (e.g.,  diffuse reflectance infrared Fourier transform spectroscopy), foreshadowing a pathway for the development of multifunctional MOF-based reagent-catalyst cargo vessels for reactive reagents, as an attractive alternative to the use of toxic pure gases or gas generators.