Morphology Control of Zr-Based Luminescent Metal-Organic Frameworks for Aflatoxin B1 Detection

Metal-organic frameworks (MOFs) have gained significant prominence as sensing materials owing to their unique properties. However, understanding the correlation between the morphology, properties, and sensing performance in these MOF-based sensors remains a challenge, limiting their applications and potential for improvement. In this study, Zr-MOF was chosen as an ideal model to explore the impact of the MOF morphology on the sensing performance, given its remarkable stability and structural variability. Three luminescent MOFs (namely rod-like Zr-LMOF, prismoid-like Zr-LMOF, and ellipsoid-like Zr-LMOF) were synthesized by adjusting the quantities of the benzoic acid and the reaction time. More importantly, the sensing performance of these Zr-LMOFs in response to aflatoxin B1 (AFB1) was thoroughly examined. Notably, the ellipsoid-like Zr-LMOF exhibited significantly higher sensitivity compared to other Zr-LMOFs, attributed to its large specific surface area and pore volume. Additionally, an in-depth investigation into the detection mechanism of AFB1 by Zr-LMOFs was conducted. Building upon these insights, a ratiometric fluorescence sensor was developed by coordinating Eu3+ with ellipsoid-like Zr-LMOF, achieving a remarkably lower detection limit of 2.82 nM for AFB1. This study contributes to an improved comprehension of the relationship between the MOF morphology and the sensing characteristics while presenting an effective approach for AFB1 detection.

Effective Removal of Humic Acid by Zr−MOFs with Surface Modification

Humic acid (HA) in makeup water is one of the important safety issues of high−parameter power plants. Herein, the Zr−based metal organic frameworks (Zr−MOFs) were applied to remove humic acid in water. The mesoporous and active sites of Zr−MOFs were controlled by different ratios of ligands to increase the adsorption of HA. The maximum adsorption capacity was 150.15 mg g−1. The morphology and adsorption properties of the Zr−MOFs were characterized using scanning electron microscopy (SEM), X−ray diffraction (XRD), surface charge, Fourier Transform infrared (FT−IR), N2 adsorption−desorption and adsorption test. The adsorption process of HA accorded with the pseudo−second−order kinetics, while the adsorption isotherm conformed to the Langmuir model and the adsorption was proved to be a spontaneous and endothermic process. Physical adsorption by the mesoporous materials and the hydrogen bonding interactions between the Zr−MOFs and HA were the driving forces of HA adsorption. These results provided useful information for the effective removal of HA and enhanced our understanding of the adsorption mechanism of HA on Zr−MOFs.

Homochiral porous coordination polymer of EuIII for metal ion sensing and enantioselective adsorption

A novel multifunctional homochiral porous metal–organic framework was obtained by combining the luminescent component Eu(iii) with an enantiopure triangular polycarboxylic ligand.

Three-dimensional Cd(ii) porphyrin metal–organic frameworks for the colorimetric sensing of Electron donors

Three MOFs with metalloporphyrin lined, large square 1D channels were used as colorimetric sensors for electron donors. Exposure to amine vapours caused a redshift of the Soret absorption bands of the metalloporphyrin.

Structurally Engineered Light-Responsive Nanozymes for Enhanced Substrate Specificity

Mimicking enzyme specificity via construction of on-demand geometric structures on nanozymes is of great interest in recent years. Although building substrate-specific polymers on nanozymes has achieved great success, polymer-blocked active sites would inevitably lead to decreased activity of nanozymes. Here, we have developed three photoactive metal-organic framework (MOF)-based nanozymes (called 2D-TCPP, 3D-TCPP, and AD-TCPP), which have different geometric structures as well as unshielded active sites. Together with their structural variations and excellent photoresponsive oxidase-like activities, these photoactive nanozymes exhibit structure-dependent specificity for three kinds of substrates (typical oxidase substrates, organic pollutants, and antioxidants). Moreover, AD-TCPP and 3D-TCPP show potential applications for environmental protection and bioanalysis, respectively. This work offers a promising approach to the development of nanozymes with enzyme-like specificity.

Structural diversity of nanoscale zirconium porphyrin MOFs and their photoactivities and biological performances

Photoactive MOF-based delivery systems are highly attractive for photodynamic therapy (PDT), but the fundamental interplay among structural parameters and photoactivity and biological properties of these MOFs remains unclear. Herein, porphyrinic MOF isomers (TCPP-MOFs), constructing using the same building blocks into distinct topologies, have been selected as ideal models to understand this problem. Both the intramolecular distances and molecular polarization within TCPP-MOFs isomers collectively contribute to the photoactivity of generating reactive oxygen species. Remarkably, the morphology-determined endocytic pathways and cytotoxicity, as well as good biocompatibility have been confirmed for TCPP-MOF isomers without any chemical modification for the first time. Besides the topology-dependent photoactive regulation, this work also provides in-depth insights into the biological effect from the MOF nanoparticles with controllable structural factors, benefiting further in vivo applications and clinical transformation.

Integrated Photoresponsive Alkaline Earth Metal Coordination Networks: Synthesis, Topology, Photochromism and Photoluminescence Investigation

Photoresponsive materials are a key part of the age of smart technology that have potential in a broad range of applications. Coordination networks (CNs) are widely used due to their designability and stability. In this work, three novel alkaline earth metal coordination networks (AEM-CNs): [Mg(CMNDI)(H₂ O)₂ ], [Ca(CMNDI)(H₂ O)₂ ]⋅H₂ O, and [Sr(CMNDI)(H₂ O)(DMF)] with fsl, cds, and scn topology nets were synthetized via N,N'-bis(carboxymethyl)-1,4,5,8-naphthalenediimide (H₂ CMNDI); the scn net is not found in the Reticular Chemistry Structure Resource or ToposPro. The reusable and sensitive photochromic properties of the three CNs enable them to be used as secret inks or ultraviolet detectors. In addition, the CNs also exhibited reusable photoluminescent turn-off toward the drug molecules, balsalazide disodium (Bal.) and colchicine (Col.), with good limits of detection of 0.16 and 0.70 μM. To the best of our knowledge, this is the first study of a fluorescence sensor for Bal. Thus, the AEM-CNs provide a design idea for integrated photoresponsive materials that could be further improved in the near future by further study.

Stable Indium Pyridylcarboxylate Framework with Highly Selective Adsorption of Cationic Dyes and Effective Nitenpyram Detection

On the basis of an undeveloped asymmetrical pyridylcarboxylate ligand, 2-(2-carboxypyridin-4-yl)terephthalic acid (H₃CPTA), an indium pyridylcarboxylate framework, [(Me)₂NH₂]_1.5[In_1.5(CPTA)₂]·5.5NMF·6H₂O (1), is synthesized under solvent thermal conditions. 1 displays a 3D anionic framework with a large void space, which contains open square channels with a cross section of 14.6 Å and a pore surface decorated with carboxylic oxygen atoms. Depending on the anionic skeleton and high water stability, 1 exhibits high adsorption selectivity and capacity for cationic dyes in aqueous solution. Furthermore, the luminescence performance illustrates that 1 has selectivity and sensitivity to nitenpyram with good recyclability.

A 2-Fold Interpenetrated Nitrogen-Rich Metal-Organic Framework: Dye Adsorption and CO2 Capture and Conversion

A bifunctional ligand strategy for modification of the functional pores is of great significance in the structural design of metal-organic frameworks (MOFs). Herein, a new 2-fold interpenetrated "pillared-layer" 3D Co-MOF, {[Co(HL)(4,4'-bipy)]·DMF·2H₂O}_n (1), was successfully synthesized by using two kinds of ligands, imidazolecarboxylic acid and pyridine. The metal-carboxylic layers are pillared by the 4,4'-bipy ligand, displaying a 3D framework with rectangular 3D channels (high BET surface of 190.9 m² g^-1 and maximum aperture of 3.9 Å) that are decorated with abundant uncoordinated N and O atoms. 1 shows good water stability and thermal stability (320 °C). The proper pores and active sites endowed 1 with a selective adsorption of Congo red in aqueous solution. In addition, a high CO₂ adsorption capacity and an excellent CO₂ chemical conversion were observed.

Metalloporphyrinic metal-organic frameworks: Controlled synthesis for catalytic applications in environmental and biological media

Recently, as a new sub-family of porous coordination polymers (PCPs), porphyrinic-MOFs (Porph-MOFs) with biomimetic features have been developed using porphyrin macrocycles as ligands and/or pillared linkers. The control over the coordination of the porphyrin ligand and its derivatives however remains a challenge for engineering new tunable Porph-MOF frameworks by self-assembly methods. The key challenges exist in the following respects: (i) collapse of the large open pores of Porph-MOFs during synthesis, (ii) deactivation of unsaturated metal-sites (UMCs) by axial coordination, and (iii) the tendency of both coordinated moieties (at peripheral meso- and beta-carbon sites) and the N₄-pyridine core to coordinate with metal cations. In this respect, this review covers the advances in the design of Porph-MOFs relative to their counterpart covalent organic frameworks (Porph-COFs). The potential utility of custom-designed porphyrin/metalloporphyrins ligands is highlighted. Synthesis strategies of Porph-MOFs are also illustrated with modular design of hybrid guest@host composites (either Porph@MOFs or guest@Porph-MOFs) with exceptional topologies and stability. This review summarizes the synergistic benefits of coordinated porphyrin ligands and functional guest molecules in Porph-MOF composites for enhanced catalytic performance in various redox applications. This review shed lights on the engineering of new tunable hetero-metals open active sites within (metallo)porphyrin-MOFs as out-of-the-box platforms for enhanced catalytic processes in chemical and biological media.

Novel 3D anionic heterometallic frameworks based on trinuclear CoII and trinuclear LnIII motifs displaying slow magnetic relaxation and selective adsorption of methylene blue

3D CoLn heterometallic frameworks have been synthesized. CoDy and CoHo show slow magnetic relaxation behavior. CoTb exhibits excellent adsorption capacity for methylene blue.

Highly Stable Copper(I)-Thiacalix[4]arene-Based Frameworks for Highly Efficient Catalysis of Click Reactions in Water

Environmentally friendly metal-organic frameworks (MOFs) have gained considerable attention for their potential use as heterogeneous catalysts. Herein, two Cu^I -based MOFs, namely, [Cu₄ Cl₄ L]⋅CH₃ OH⋅1.5 H₂ O (1-Cl) and [Cu₄ Br₄ L]⋅DMF⋅0.5 H₂ O (1-Br), were assembled with new functionalized thiacalix[4]arenes (L) and halogen anions X^- (X=Cl and Br) under solvothermal conditions. Remarkably, catalysts 1-Cl and 1-Br exhibit great stability in aqueous solutions over a wide pH range. Significantly, MOFs 1-Cl and 1-Br, as recycled heterogeneous catalysts, are capable of highly efficient catalysis for click reactions in water. The MOF structures, especially the exposed active Cu^I sites and 1D channels, play a key role in the improved catalytic activities. In particular, their catalytic activities in water are greatly superior to those in organic solvents or even in mixed solvents. This work proposes an attractive route for the design and self-assembly of environmentally friendly MOFs with high catalytic activity and reusability in water.

Stomatocyte-like hollow polydopamine nanoparticles for rapid removal of water-soluble dyes from water

Stomatocyte-like hollow polydopamine nanoparticles can rapidly sequester MB from water in 20 s with a high adsorption capacity of 2896 mg g⁻¹.