Water-stable Metal-organic Frameworks Research Articles

Water-Stable High-Entropy Metal-Organic Framework Nanosheets for Photocatalytic Hydrogen Production.

Metal-organic frameworks (MOFs) have emerged as promising platforms for photocatalytic hydrogen evolution reaction (HER) due to their fascinating physiochemical properties. Rationally engineering the compositions and structures of MOFs can provide abundant opportunities for their optimization. In recent years, high-entropy materials (HEMs) have demonstrated great potential in the energy and environment fields. However, there is still no report on the development of high-entropy MOFs (HE-MOFs) for photocatalytic HER in aqueous solution. Herein, the authors report the synthesis of a novel p-type HE-MOFssingle crystal (HE-MOF-SC) and the corresponding HE-MOFsnanosheets (HE-MOF-NS) capable of realizing visible-light-driven photocatalytic HER. Both HE-MOF-SC and HE-MOF-NS exhibit higher photocatalytic HER activity than all the single-metal MOFs, which are supposed to be ascribed to the interplay between the different metal nodes in the HE-MOFsthat enables more efficient charge transfer. Moreover, impressively, the HE-MOF-NS demonstrates much higher photocatalytic activity than the HE-MOF-SC due to its thin thickness and enhanced surface area. At optimum conditions, the rate of H2 evolution on the HE-MOF-NS is ≈13.24 mmol h-1 g-1, which is among the highest values reported for water-stable MOF photocatalysts. This work highlights the importance of developing advanced high-entropy materials toward enhanced photocatalysis.

Novel Metal–Organic Framework Nanoparticle for Letrozole Delivery: A New Advancement in Breast Cancer Treatment

Water-stable metal-organic frameworks based on UIO-66@NH2 were synthesized to transport Letrozole into breast cancer cells. The UIO-66@NH2 nanoparticles had a spherical shape and triangular base pyramid morphology, with a size range of 100-200 nm. Fourier transform infrared spectroscopy confirmed the efficient adsorption of Letrozole on UIO-66@NH2. The drug release profile showed a gradual, pH-dependent release of Letrozole from the nanoparticles, with a significant increase in acidic environments, indicating the adaptable release potential of UIO-66@NH2@Let in the breast cancer microenvironment. The size and entrapment efficiency were more stable at 4 °C than at 25 °C. To evaluate the cytotoxic effects of UIO-66@NH2@Let, MTT assay, gene expression analysis, flow cytometry, reactive oxygen species generation, migration assay, and DAPI staining were performed. Moreover, according to IC50 results, the incorporation of Letrozole into UIO-66@NH2 significantly improved its anticancer activity. The results also showed that the developed formulations induced apoptosis through both intrinsic and extrinsic pathways and inhibited cancer progression. The efficacy of the formulations in inducing apoptosis was validated by DAPI staining microscopy and flow cytometry analysis. Therefore, the Letrozole-loaded UIO-66@NH2 MOFs developed in this study can be considered as a unique and sophisticated anticancer delivery nanosystem with promising in vitro anticancer properties.

Small Channels Assembled by Multilayer ZIF-8 in Nanocomposite Membranes for Filtration of Ofloxacin in Water.

Metal-organic framework (MOF)-based hybrid membranes still face many unsolved difficulties in the field of liquid separation, with a reliable production technique standing out, in particular, for the water-stable MOF membranes. In this study, zeolitic imidazolate framework-8 (ZIF-8) with acceptable water stability, favorable polymer affinity, and high selectivity was meticulously grafted on commercial poly(vinylidene fluoride) (PVDF) via substrate carboxylation-assisted etching and then overlaid onto PVDF to fabricate a novel hybrid membrane by a layer-by-layer self-assembly method. The optimal membrane manufacturing conditions, including assembly time (10 min), Hmim/Zn2+ molar ratio (8:1), and optimal layer number (three layers), were thoroughly investigated for cutting-off ofloxacin in water filtration. Under low pressure, a nanofiltration scale permeability of about 199.2 L m-2 h-1 MPa-1 and 97.9% rejection of ofloxacin were obtained in bench-scale tests based on the synergistic effect of the Donnan effect and steric hindrance. More significantly, the resulting hybrid membrane demonstrated excellent hydrophilicity, high antifouling, and mechanical and repeatability performances, suggesting promising application possibilities in real-world wastewater filtering settings.

Glyme-functionalized ligand based MOF: A comprehensive study on copper and zirconium frameworks

In this study, the synthesis of a series of novel glyme-modified ligands and their corresponding copper and zirconium metal-organic frameworks (MOF) has been successfully realized. In addition, while using copper salts, it was possible to yield a water-stable MOF. Besides, the utilization of zirconium salts resulted in the formation of MOF exhibiting a UiO-68 type structure. The thorough characterization of these MOF was performed using Single Crystal X-ray Diffraction (SCXRD), Powder X-ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA) and nitrogen adsorption-desorption isotherms.Furthermore, the CO2 adsorption capacity of these MOF was also evaluated. Despite the significant differences in their crystalline networks, all MOF exhibited appreciable CO2 adsorption capacities, ranging from 0.6 to 1.3 mmol g−1 at ambient pressure and 0 °C.

Harvesting Water from Air with High-Capacity, Stable Furan-Based Metal-Organic Frameworks.

We synthesized two isoreticular furan-based metal-organic frameworks (MOFs), MOF-LA2-1(furan) and MOF-LA2-2(furan) with rod-like secondary building units (SBUs) featuring 1D channels, as sorbents for atmospheric water harvesting (LA = long arm). These aluminum-based MOFs demonstrated a combination of high water uptake and stability, exhibiting working capacities of 0.41 and 0.48 gwater/gMOF (under isobaric conditions of 1.70 kPa), respectively. Remarkably, both MOFs showed a negligible loss in water uptake after 165 adsorption-desorption cycles. These working capacities rival that of MOF-LA2-1(pyrazole), which has a working capacity of 0.55 gwater/gMOF. The current MOFs stand out for their high water stability, as evidenced by 165 cycles of water uptake and release. MOF-LA2-2(furan) is the first aluminum MOF to employ a double 'long arm' extension strategy, which is confirmed through single-crystal X-ray diffraction (SCXRD). The MOFs were synthesized by using a straightforward synthesis route. This study offers valuable insights into the design of durable, water-stable MOFs and underscores their potential for efficient water harvesting.

Water-stable metal-organic frameworks (MOFs): rational construction and carbon dioxide capture.

Metal-organic frameworks (MOFs) are considered to be a promising porous material due to their excellent porosity and chemical tailorability. However, due to the relatively weak strength of coordination bonds, the stability (e.g., water stability) of MOFs is usually poor, which severely inhibits their practical applications. To prepare water-stable MOFs, several important strategies such as increasing the bonding strength of building units and introducing hydrophobic units have been proposed, and many MOFs with excellent water stability have been prepared. Carbon dioxide not only causes a range of climate and health problems but also is a by-product of some important chemicals (e.g., natural gas). Due to their excellent adsorption performances, MOFs are considered as a promising adsorbent that can capture carbon dioxide efficiently and energetically, and many water-stable MOFs have been used to capture carbon dioxide in various scenarios, including flue gas decarbonization, direct air capture, and purified crude natural gas. In this review, we first introduce the design and synthesis of water-stable MOFs and then describe their applications in carbon dioxide capture, and finally provide some personal comments on the challenges facing these areas.

Cooperativity between coordinative unsaturated Fe(iii) and aryl-π electrons in MIL-100(Fe) for adsorption of small molecules

Coordinatively unsaturated sites and aryl-π electrons coorperatively affect the adsorption of aromatics with polar groups.

Water-Stable Microporous Bipyrazole-Based Framework for Efficient Separation of MTO Products.

Recently, methanol-to-olefins (MTO) technology has been widely used. The development of new adsorbents to separate MTO products and obtain high-purity ethylene (C2H4) and propylene (C3H6) has become an urgent task. Herein, an exceptionally highly water-stable metal-organic framework (MOF), [Cu3(OH)2(Me2BPZ)2]·(solvent)x (1) (H2Me2BPZ = 3,3'-dimethyl-1H,1'H-4,4'-bipyrazole) with hexagonal pores, has been elaborately designed and constructed. After being soaked in water for 7 days, it still maintains its structure, and the uptake of N2 at 77 K is unchanged. The adsorption capacity of C3H6 can reach 138 cm3 g-1, while the uptake of C2H4 is only 52 cm3 g-1 at 298 K and 1 bar. The dynamic breakthrough experiments show that the mixture of C3H6/C2H4 (50/50, v/v) can be efficiently separated in one step. High-purity C2H4 and C3H6 can be obtained through an adsorption and desorption cycle and the yields of C2H4 (purity ≥ 99.95%) and C3H6 (purity ≥ 99%) are 84 and 48 L kg-1, respectively. Surprisingly, when the flow rate is increased, the separation performance has no obvious change. Additionally, humidity has no effect on the separation performance. Finally, theoretical simulations indicate that there are stronger interactions between the C3H6 molecule and the framework, which are beneficial to capturing C3H6 over C2H4.

Pore engineering of a Quasi-MOF-801 with unsaturated metal site and modulate porosity for selective and effective phosphate uptake

MOF-801, a highly water-stable metal-organic framework, underwent carefully monitored thermal treatment at temperatures between 240 and 300 °C for the development of defective quasi-MOF. The treatment leads to the formation of structural defects, more porosity, and the elimination of ligands. The resulting quasi-MOF-801, which structurally connects crystalline materials and the associated metal oxides, serves as a unique and very effective phosphate adsorbent thanks to its many free adsorption sites. The findings showed that the free open metals site was crucial in forming the binding with phosphate. Q-M801-280 (quasi MOF-801 heated to 280 °C) exhibited the highest adsorption capacity (415 mg. g−1) with a broad pH range of 3–11 and high phosphate selectivity when there are competing anions present. The created Q801-280 is an effective adsorbent that may be utilized to reduce the growing eutrophication of water through phosphate uptake.

Green, Safe, and Reliable Synthesis of Bimetallic MOF-808 Nanozymes With Enhanced Aqueous Stability and Reactivity for Biological Applications.

Bimetallic metal-organic frameworks (MOFs) are promising nanomaterials whose reactivity towards biomolecules remains challenging due to issues related to synthesis, stability, control over metal oxidation state, phase purity, and atomic level characterization.Here, these shortcomings are rationally addressed through development of a synthesis of mixed metal Zr/Ce-MOFs in aqueous environment, overcoming significant hurdles in the development of MOF nanozymes, sufficiently stable on biologically relevant conditions. Specifically, a green and safe synthesis of Zr/Ce-MOF-808 is reported in water/acetic acid mixture which affords remarkably water-stable materials with reliable nanozymatic reactivity, including MOFs with a high Ce content previously reported to be unstable in water. The new materials outperform analogous bimetallic MOF nanozymes, showcasing that rational synthesis modifications could impart outstanding improvements. Further, atomic-level characterization by X-ray Absorption Fine Structure (XAFS) and X-ray Diffraction (XRD) confirmed superior nanozymes arise from differences in the synthetic method, which results in aqueous stable materials, and Ce incorporation, which perturbs the ligand exchange dynamics of the material, and could ultimately be used to fine tune the intrinsic MOF reactivity. Similar rational strategies which leverage metals in a synergistic manner should enable other water-stable bimetallic MOF nanozymes able to surpass existing ones, laying the path for varied biotechnological applications.

Novel Strategy to Enhance Human Mesenchymal Stromal Cell Immunosuppression: Harnessing Interferon-Gamma Presentation in Metal-Organic Frameworks Embedded on Heparin/Collagen Multilayers.

The immunomodulatory potential of human mesenchymal stromal cells (hMSCs) can be boosted when exposed to interferon-gamma (IFN-γ). While pretreating hMSCs with IFN-γ is a common practice to enhance their immunomodulatory effects, the challenge lies in maintaining a continuous IFN-γ presence within cellular environments. Therefore, in this research, we investigate the sustainable presence of IFN-γ in the cell culture medium by immobilizing it in water-stable metal-organic frameworks (MOFs) [PCN-333(Fe)]. The immobilized IFN-γ in MOFs was coated on top of multilayers composed of combinations of heparin (HEP) and collagen (COL) that were used as a bioactive surface. Multilayers were created by using a layer-by-layer assembly technique, with the final layer alternating between collagen (COL) and heparin (HEP). We evaluated the viability, differentiation, and immunomodulatory activity of hMSCs cultured on (HEP/COL) coated with immobilized IFN-γ in MOFs after 3 and 6 days of culture. Cell viability, compared to tissue culture plastic, was not affected by immobilized IFN-γ in MOFs when they were coated on (HEP/COL) multilayers. We also verified that the osteogenic and adipogenic differentiation of the hMSCs remained unchanged. The immunomodulatory activity of hMSCs was evaluated by examining the expression of indoleamine 2,3-dioxygenase (IDO) and 11 essential immunomodulatory markers. After 6 days of culture, IDO expression and the expression of 11 immunomodulatory markers were higher in (HEP/COL) coated with immobilized IFN-γ in MOFs. Overall, (HEP/COL) multilayers coated with immobilized IFN-γ in MOFs provide a sustained presentation of cytokines to potentiate the hMSC immunomodulatory activity.

Water-stable methyl-modified MOF and mixed matrix membrane for efficient adsorption and separation of cationic dyes

The water stability of typical metal–organic frameworks (MOFs) limits the practical applications in water, such as pollutants adsorption. In this work, through the pre-functionalization of hydrophobic methyl groups on the ligand, anionic Bio-MOF-1 was transformed into Bio-MOF-2Me which has excellent water stability, even in acidic and boiling water environments. Bio-MOF-2Me also keeps the negative Zeta potential, enabling it to efficiently adsorbing and separating targeted dyes in mixed aqueous solution of cationic/anionic dyes, with high removal rates of around 99%. According to the Langmuir isotherm model, the maximum adsorption capacity of Bio-MOF-2Me for cationic methyl violet could reach up to 310.2 mg⋅g−1. In order to improve the portability and recyclability of Bio-MOF-2Me-based adsorbents, a mixed matrix membrane (MMM) of Bio-MOF-2Me (Bio-MOF-2Me-MMM) was manufactured. Bio-MOF-2Me-MMM inherits the preferential adsorption and separation properties of Bio-MOF-2Me, which has a maximum adsorption capacity of 157.1 mg⋅g−1 for cationic methyl violet. The adsorption abilities of both Bio-MOF-2Me and Bio-MOF-2Me-MMM own good cyclic reversibility, and the removal efficiency respectively retained 82% (Bio-MOF-2Me) and 72% (Bio-MOF-2Me-MMM) even after five adsorption–desorption cycles. The water stability, good adsorption/separation ability, portability and reusability make ionic Bio-MOF-2Me-MMM a promising candidate for dye wastewater treatment.

A water-stable metal–organic framework Zn-MOF as a chemical sensor for efficient detection of Cr(VI) (Cr2O72- and CrO42-) anions in water

The luminescent three-dimensional Zn(II) metal–organic framework (Zn-MOF) was successfully synthesized via a hydrothermal method. The structure of the compound is denoted as [Zn3(μ3-OH)(L)·(H2O)]n, where H5L represents 3,5-bis(3,5-dicarboxyphenoxy)benzoic acid. Remarkably, this framework exhibits excellent stability in water and pH (3–13) conditions. Intriguingly, the compound shows high selectivity, sensitivity, and low detection limits (4.10 μM for Cr2O72- and 6.63 μM for CrO42-) in aqueous solution. Furthermore, the material proves to be easily regenerable. Additionally, the competition between analyte absorption and the excitation/emission of Zn-MOF elucidates the fluorescence sensing mechanism of Cr2O72-/CrO42- ions. These findings unequivocally establish Zn-MOF as a highly selective and recyclable fluorescence sensing material for the quantitative detection of Cr(VI) ions in aqueous solutions.

UsCNT-assisted synthesis of water-stable MOF nanosheet for highly proton-conducting membrane

Proton exchange membrane (PEM) with ordered and stable pathway is highly desirable for use in proton exchange membrane fuel cells. Porous MOF materials hold great promise for the development of high-performance PEM due to the pre-designable and ordered pore structure, providing regular transfer channel. However, the developed water-stable MOFs usually require hydrophobic pores for stabilizing crystal structure in moisture circumstances. It leads to dramatically declined proton conductivity at low relative humidity (RH) because of severe water loss. Herein, we propose the fabrication of hydrophilic and water-stable MOF nanosheets (usCNT@CuTCPP, ∼2.8 nm) through ultrashort carbon nanotube (usCNT)-assisted self-inhibition crystal growth strategy. Then, ∼ 8.9 μm-thick usCNT@CuTCPP lamellar membrane was prepared by self-stacking of nanosheets. We demonstrate that in-situ incorporation of usCNT could promote membrane hydration, enabling usCNT@CuTCPP-M excellent structural stability in water and remarkable water adsorption and retention ability. This allows the construction of continuous hydrogen-bond networks, thereby affording membrane efficient proton conduction under low RH. Additionally, usCNT@CuTCPP membrane with encapsulation of phytic acid exhibits high proton conductivities of 71 and 124 mS cm−1 under 40% and 100% RH, respectively, superior to Nafion and most porous matrix conductors. The assembled hydrogen fuel cell exhibits high performance over wide RH ranges.

A novel fluorescence sensor for sensitive detection of zearalenone using a polyvinylpyrrolidone-modified Zr(IV)-based metal-organic framework

Zearalenone (ZEN) is a mycotoxin that is a potential threat to food safety and human health. Therefore, there is a need for sensitive and convenient methods to detect ZEN in food samples. Zirconium-based metal-organic frameworks (Zr-MOFs) are considered one of the most robust water-stable MOFs, with diverse luminescent organic ligands and tunable porosity, render them promising candidates for fluorescence sensors. In this work, we have developed a fluorescence sensor for ZEN detection based on Polyvinylpyrrolidone-modified Zr-MOF (PVP-UiO-67), by finely adjusting the pore size of the Zr-MOF family. The incorporation of PVP into UiO-67 noticeably enhances its water dispersibility and stability. Remarkably, the fluorescence of PVP-UiO-67 is selectively and sensitively quenched by ZEN, offering a detection limit as low as 7.44 nM and a linear response ranging from 0.016 to 3.14 μM. The potential sensing mechanisms associated with PVP-UiO-67 have further research, suggesting that the quenching process may be a synergistic effect of dynamic and static quenching and inner filter effect. This work validates the prospective utility of PVP-UiO-67 as an emergent fluorescence sensor for the detection of ZEN in real-world samples.

Construction of a Cd(II)-Based Metal-Organic Framework for Selective Luminescent Sensing of Chloramphenicol in Milk and Honey Samples

A new and water-stable metal-organic framework, [Cd2(L)2(tmd)]·3H2O (MOF 1), was successfully synthesized by mixed ligands of H2L and tmd under solvothermal condition (H2L= 5-acetamidoisophthalic acid, tmd= 4,4-trimethylenedipyridine). Single-crystal X-ray diffraction shows that the structural unit of MOF 1 is a tetranuclear [Cd4(L)6] primary building unit. Fluorescence sensing experiments revealed that MOF 1 exhibited selectivity and sensitivity detection of Chloramphenicol (CHL) antibiotic in aqueous solutions. The fluorescence quenching effect showed that MOF 1 had a very low detection limit for CHL (LOD= 0.11 μM). More importantly, MOF 1 can be used as a new fluorescence sensor for the detection of CHL in milk and honey samples with very good recoveries of 98.2-103.0 % and 97.0-98.9 %, respectively. Furthermore, the internal filtration effect (IFE) and photoelectron electron transfer (PET) may be responsible for the fluorescence quenching efficiency.

Microporous Organic Network: Superhydrophobic Coating to Protect Metal-Organic Frameworks from Hydrolytic Degradation.

Despite the rapid development of versatile metal-organic frameworks (MOFs), the synthesis of water-stable MOFs remains challenging, which significantly limits their practical applications. Herein, a novel engineering strategy was developed to prepare superhydrophobic MOFs by an in situ fluorinated microporous organic network (FMON) coating. Through controllable modification, the resulting MOF@FMON retained the porosity and crystallinity of the pristine MOFs. Owing to the superhydrophobicity of the FMON and the feasibility of MOF synthesis, the FMON coating could be in situ integrated with various water-sensitive MOFs to provide superhydrophobicity. The coating thickness and hydrophobicity of the MOF@FMON composites were easily regulated by changing the FMON monomer concentration. The MOF@FMON composites exhibited excellent oil/water separation and catalytic activities and enhanced durability in aqueous solutions. This study provides a general approach for the synthesis of superhydrophobic MOFs, expanding the application scope of MOFs.

Efficient accumulation integrated with selective degradation of micropollutants under irradiation of visible light by the size-exclusion effect of metal–organic framework

Developing multifunctional materials for efficiently removing pharmaceutical active compounds (PACs) in water matrix that coexisted with humic acid (HA) is in high demand. Water-stable metal–organic frameworks (MOFs) with tunable porous structures have aroused great attention as versatile adsorbents. However, further eliminating pollutants, especially in practical applications, needs more exploration. In this study, rational modification of UiO-66 (Ce) with a minimum amount of CdS could regulate the highly developed cavities and subsequently promote the selective interfacial degradation of four PACs, including non-steroidal anti-inflammatory drugs and antibiotics with lower concentrations (100 μg/L) detected by HPLC-MS/MS were selected as the model compounds. The adsorption ability of the composites was 11.84 ∼ 12.21 times higher than CdS, and the overall removal efficiency was 1.31 and 2.18 times higher than that of UiO-66 (Ce) and CdS, respectively, via h+ and •O2– generated in simulated HA-containing wastewater. This modification features excellent resistance towards HA (2 mg/L ∼ 10 mg/L) during adsorption and photocatalytic degradation effectively. In comparison, competitive anions (Cl-, SO42-, CO32–, HCO3–) with smaller sizes affect ROS formation significantly, indicating the possible exclusion effect of competitors by particular sizes. This study offers a facile strategy to remove PACs and HA-containing water effectively.

Computational Insights into the Mechanism of Nitric Oxide Generation from S-Nitrosoglutathione Catalyzed by a Copper Metal-Organic Framework.

The controlled generation of nitric oxide (NO) from endogenous sources, such as S-nitrosoglutathione (GSNO), has significant implications for biomedical implants due to the vasodilatory and other beneficial properties of NO. The water-stable metal-organic framework (MOF) Cu-1,3,5-tris[1H-1,2,3-triazol-5-yl]benzene has been shown to catalyze the production of NO and glutathione disulfide (GSSG) from GSNO in aqueous solution as well as in blood. Previous experimental work provided kinetic data for the catalysis of the 2GSNO → 2NO + GSSG reaction, leading to various proposed mechanisms. Herein, this catalytic process is examined using density functional theory. Minimal functional models of the Cu-MOF cluster and glutathione moieties are established, and three distinct catalytic mechanisms are explored. The most thermodynamically favorable mechanism studied is consistent with prior experimental findings. This mechanism involves coordination of GSNO to copper via sulfur rather than nitrogen and requires a reductive elimination that produces a Cu(I) intermediate, implicating a redox-active copper site. The experimentally observed inhibition of reactivity at high pH values is explained in terms of deprotonation of a triazole linker, which decreases the structural stability of the Cu(I) intermediate. These fundamental mechanistic insights may be generally applicable to other MOF catalysts for NO generation.

Mercury Clathration-Driven Phase Transition in a Luminescent Bipyrazolate Metal-Organic Framework: A Multitechnique Investigation.

Mercury is one of the most toxic heavy metals. By virtue of its triple bond, the novel ligand 1,2-bis(1H-pyrazol-4-yl)ethyne (H2BPE) was expressly designed and synthesized to devise metal-organic frameworks (MOFs) exhibiting high chemical affinity for mercury. Two MOFs, Zn(BPE) and Zn(BPE)·nDMF [interpenetrated i-Zn and noninterpenetrated ni-Zn·S, respectively; DMF = dimethylformamide], were isolated as microcrystalline powders. While i-Zn is stable in water for at least 15 days, its suspension in HgCl2 aqueous solutions prompts its conversion into HgCl2@ni-Zn. A multitechnique approach allowed us to shed light onto the observed HgCl2-triggered i-Zn-to-HgCl2@ni-Zn transformation at the molecular level. Density functional theory calculations on model systems suggested that HgCl2 interacts via the mercury atom with the carbon-carbon triple bond exclusively in ni-Zn. Powder X-ray diffraction enabled us to quantify the extent of the i-Zn-to-HgCl2@ni-Zn transition in 100-5000 ppm HgCl2 (aq) solutions, while X-ray fluorescence and inductively coupled plasma-mass spectrometry allowed us to demonstrate that HgCl2 is quantitatively sequestered from the aqueous phase. Irradiating at 365 nm, an intense fluorescence is observed at 470 nm for ni-Zn·S, which is partially quenched for i-Zn. This spectral benchmark was exploited to monitor in real time the i-Zn-to-HgCl2@ni-Zn conversion kinetics at different HgCl2 (aq) concentrations. A sizeable fluorescence increase was observed, within a 1 h time lapse, even at a concentration of 5 ppb. Overall, this comprehensive investigation unraveled an intriguing molecular mechanism, featuring the disaggregation of a water-stable MOF in the presence of HgCl2 and the self-assembly of a different crystalline phase around the pollutant, which is sequestered and simultaneously quantified by means of a luminescence change. Such a case study might open the way to new-conception strategies to achieve real-time sensing of mercury-containing pollutants in wastewaters and, eventually, pursue their straightforward and cost-effective purification.