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Background As a critical topic of international concern, food safety has received great attention in recent years. The hazardous substances (such as antibiotics, heavy metal ions, food additives, and foodborne bacteria) in foodstuffs would cause threat to human health and economic losses in food industry. Despite of high sensitivity, accuracy, and reliability of conventional techniques for analysis of food contaminants, they often require complicated apparatus, well-trained personalized operation, and laborious and time-consuming procedure. In this regard, new sensing strategies for convenient, fast, and sensitive detection of food contaminants should be developed for food safety. Scope and approach Metal–organic frameworks (MOFs), as a large category of porous crystalline materials, could be used as efficient platforms for constructing diverse chemosensors and biosensors, for their high porosity, adjustable compositions or structures, and good stability. A variety of MOFs, MOFs-based composites, and MOFs-based derivatives show excellent fluorescence (FL), chemical functionality, and strong bioaffinity toward probes (DNA, aptamers, or antibodies), exhibiting great potentials as FL emitters, electrode materials, or platforms of biosensors for selective and sensitive detection of hazard analytes in foodstuffs. By coupling with different determination techniques such as FL, electrochemical (EC), photoelectrochemical (PEC) or surface-enhanced Raman spectroscopy methods, MOFs-based materials have shown promising applications for detecting diverse analytes. Furthermore, the current challenges and future developments of MOFs-based materials for analysis of food contaminants have been discussed. Key findings and conclusions Although some reviews on the applications of MOFs in food packing and food safety have been documented, this comprehensive review will provide new insights to the construction of chemosensors and biosensors with MOFs-based materials for determination of food contaminants toward food safety monitoring.

We have proposed a novel electrochemical aptasensing strategy for efficiently detecting staphylococcus aureus (S. aureus) based on copper-based metal-organic framework encapsulated with plenty of Cu

Dimethyl sulfoxide (DMSO) is a universally used solvent in various synthetic reactions, and trace amounts of DMSO residual are often seen on the surface of chemical product. It is difficult to quickly determine whether the residual DMSO is washed completely. This work reports a CdII metal-organic framework (MOF) SXU-4 which can detect trace amounts of DMSO in various solvents. Fluorescence experiments reveal its turn-on fluorescence effect toward DMSO with high selectivity and sensitivity, indicating that it can be used as an effective luminescent probe for rapid chemical product purity detection by testing the washing solution. Crystallographically characterized DMSO loaded SXU-4 (DMSO@SXU-4), in combination with computational results uncover that the enhanced DMSO-MOF conjugation through multiple DMSO-MOF supramolecule interactions and charge rearrangement are the main causes of fluorescence intensification.

The self-assembly of a bifunctional organic ligand with a formate-bridged rod-shaped secondary building unit leads to a new microporous metal–organic framework (MOF). This MOF shows a moderately high C2H2 storage capacity (145 cm3/g) and an excellent adsorption selectivity for C2H2/CO2 (11) at room temperature. Furthermore, its discriminatory sorption behavior toward C2H2 and CO2 was probed by computational analysis in detail.

A series of Zr-based metal–organic framework (MOF) composites embedded with three kinds of aptamer strands (509-MOF@Apt) were achieved by a one-step de novo synthetic approach. A platform for ultrasensitive detection of analytes, namely, thrombin, kanamycin, and carcinoembryonic antigen (CEA), was also established. Considering the conformational changes caused by the binding interactions between aptamer strands and targeted molecules, the label-free electrochemical aptasensors based on 509-MOF@Apt composites could be developed to detect various target molecules. By comparing the common fabrication approaches of aptasensors, a distinct determination mechanism was presented through analysis of the electrochemical measurements on different interaction behaviors between probe aptamer strands and 509-MOF materials. The optimized aptasensors based on 509-MOFs@Apt demonstrated excellent sensitivity (with the detection limit of 0.40, 0.37, and 0.21 pg mL–1 for CEA, thrombin, and kanamycin, respectively), stabilit...

Two unique immunosensors made of aluminum-based metal-organic frameworks (MOFs), namely, 515- and 516-MOFs, with 4,4',4''-nitrilotribenzoic acid (H3NTB) were successfully obtained to efficiently assess food safety. The as-prepared 515- and 516-MOFs exhibited superior thermal and physicochemical stability, high electrochemical activity, and good biocompatibility. Among these immunosensors, 516-MOF showed a preferable biosensing ability toward analytes determined by electrochemical techniques. The developed 516-MOF-based electrochemical biosensor not only demonstrated high sensitivity with low detection limits of 0.70 and 0.40pgmL-1 toward vomitoxin and salbutamol, respectively, but also showed good selectivity in the presence of other interferences. Therefore, with the advantages of high sensitivity, good selectivity, and simple operation, this new strategy is believed to exhibit great potential for simple and convenient detection of poisonous and harmful residues in food.

To avoid the instability and inefficiency for anion-exchange resins and layered double-hydroxides materials, we present herein a flexible coordination network [Ag(L243)](NO3)(H2O)(CH3CN) (L243 = 3-(2-pyridyl)-4-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazole) with superefficient trapping capacity for permanganate, as a group-7 oxoanion model for radiotoxic pertechnetate pollutant. Furthermore, a high-throughput screening strategy has been developed based on concentration-gradient design principle to ascertain the process and mechanism for anion exchange. Significantly, a series of intermediates can be successfully isolated as the qualified crystals for single-crystal X-ray diffraction. The result evidently indicates that such a dynamic material will show remarkable breathing effect of the three-dimensional host framework upon anion exchange, which mostly facilitates the anion trapping process. This established methodology will provide a general strategy to discover the internal secrets of complicated solid-state...

Metal–organic frameworks (MOFs), as a class of adjustable porous crystalline materials, have received considerable attention in recent years. In this study, starting from an unstable MIL-88 type Co(II)-MOF as the prototype structure, two isoreticular stabilized MOFs with similar structural features but different water/thermal stabilities and acetylene sorption behaviors were prepared, which can be modulated by incorporating different functional brackets in the pores. MOF 1 equipped with open metal sites (OMSs) decomposed quickly in water solution, while the free N-donor functionalized MOF 2 could be stable in water with improved thermostability. The gas sorption study reveals that activated material 2 has a significantly enhanced acetylene uptake capacity with a lower Qst value than those of activated 1, showing a 79% increase (242 vs. 135 cm3 g−1) at 273 K and 91% increase (165 vs. 86 cm3 g−1) at 298 K. The acetylene uptake capacity of activated material 2 is extraordinarily high among MOFs without OMSs, and is even comparable to some famous MOFs with much stronger C2H2 binding ability which however require considerably higher energy for regeneration. The experimental results were further confirmed by the molecular mechanics (MM) calculations, grand canonical Monte Carlo (GCMC) simulations and density functional theory (DFT) studies.

A cage-based anionic Na(I)–organic framework with a unique Na9 cluster-based secondary building unit and a cage-in-cage structure was constructed. The selective separation of dyes with different charges and sizes was investigated. Furthermore, the Rh6G@MOF composite could be applied as a recyclable fluorescent sensor for detecting picric acid (PA) with high sensitivity and selectivity.

A terbium(III) lanthanide–organic framework (534-MOF-Tb) with a green-emission signal was successfully obtained by the solvothermal reaction of Tb3+ ions with the organic ligand H3TBOT (2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene). 534-MOF-Tb contains microporous quadrangle channels with accessible Lewis-base sites and coordinated water molecules, which are feasible to anchor and recognise multifarious analytes. It can serve as a recyclable multi-responsive sensing material for detecting Fe3+, MnO4−, Cr2O72−, and p-nitrotoluene (4-NT). Significantly, this is the first reported MOF-based sensor for detecting explosive 4-NT. Moreover, the mechanism of the selective luminescence quenching response for Fe3+, MnO4−, Cr2O72− or 4-NT can be mainly explained in terms of the competition between the absorption of the light source energy and the electronic interaction between the analyte and the TBOT ligand.

A series of nanocomposites comprised of iron oxide and mesoporous carbon (denoted as Fe3O4@mC) were derived from an Fe(II)-based metal–organic framework (525-MOF) by calcining at different temperatures. The advantages of chemical functionality, strong bioaffinity, and high stability of the Fe3O4@mC can be combined with the high specific surface area of 525-MOF leading to the formation of Fe3O4@mC nanocomposites as a scaffold for oxytetracycline (OTC) aptamer strands. The use of Fe3O4@mC nanocomposites reveals high OTC detection efficiency. The nanocomposite calcined at 900 °C (denoted as Fe3O4@mC900) is found to be the best candidate toward high-sensitivity and high-selectivity detection of OTC because of its excellent functionality, nanostructural properties, and high electrochemical performance. Accordingly, the Fe3O4@mC900-based electrochemical aptasensor displays high sensitivity with a low detection limit of 0.027 pg mL−1 within a broad linear range of OTC concentration from 0.005 to 1.0 ng mL−1. The aptasensor also exhibits high selectivity, reproducibility, stability, regenerability, and applicability in milk samples. All of these results indicate that the Fe3O4@mC nanocomposites that originated from 525-MOF can be applied in the fields of trace and fast antibiotic determination.

Two isostructural CoII-based metal–organic frameworks (MOFs) with the opposite framework charges have been constructed, which can be simply controlled by changing the tetrazolyl or triazolyl terminal in two bifunctional ligands. Notably, the cationic MOF 2 can adsorb much more C2H2 than the anionic MOF 1 with an increase of 88 % for C2H2 uptake at 298 K in spite of more active nitrogen sites in 1. Theoretical calculations indicate that both nitrate and triazolyl play vital roles in C2H2 binding and the C2H2 adsorption isotherm confirms that the enhanced C2H2 uptake for 2 (225 and 163 cm3g−1 at 273 and 298 K) is exceptionally high for MOF materials without open metal sites or uncoordinated polar atom groups on the frameworks.

To further explore the coordination possibilities of the flexible tripodal ligand, 4,4′,4′′-(benzene-1,3,5-triyl-tris(oxy))tribenzoic acid (H3BTTB), two solvent-controlled three-dimensional (3D) manganese(II) coordination polymers, [Mn3(BTTB)2(H2O)4](H2O)2 (1) and [Mn3(BTTB)2(DMF)2](DMF)2 (2), were synthesized and characterized. Single crystal X-ray diffraction analysis indicates that in the MnII complexes the BTTB ligands exhibit two coordination modes, which have not been reported previously. Complexes 1 and 2 involve different one-dimensional (1D) rod-shaped metal–carboxylate secondary building units (SBUs). The 1D SBUs are further extended to afford two different three-dimensional (3D) frameworks with similar flu topology via linkage of the BTTB ligands. The results demonstrate that the reaction solvent as well as conformation and coordination mode of BTTB ligands play key roles on the formation of the final framework structures. Additionally, their luminescent properties were investigated.

A (6, 14)-connected metal-organic framework (MOF), namely [Co9(μ3-OH)2(CPT)10(HCOO)6]n (1) [HCPT = 4-(4-carboxyphenyl)-1, 2,4-triazole], was synthesized using custom-designed bifunctional triazolate-carboxylate organic linkers and CoII salts. The framework exhibits two types of highly connected Co3 and Co6 cluster moieties with distinct arrangement, which were generated in situ. The combination of these building units results in an unusual (6, 14)-connected structure, which has been rarely observed in MOF chemistry. This MOF was characterized by single X-ray diffraction, PXRD, and TGA. Furthermore, its magnetic properties were investigated.

A new Li(I)-based metal–organic framework (MOF), namely {(Me2NH2)2[Li(NTB)](H2O)3(DMF)2}n (1, NTB = 4.4′,4″-nitrilotrisbenzoate; DMF = N,N-dimethylformamide), has been successfully achieved by solvothermal reaction of a C3-symmetric tricarboxytriphenylamine based ligand and Li(I) ion. The resulting framework features a binuclear Li(I) secondary building unit (SBU) and a rare 3.6-connected ant topology. Luminescence properties of 1 towards different metal ions and solvents have also been investigated systematically, with emission intensities significantly quenched towards Fe(III) ion and nitrobenzene (NB). The quenching mechanism has also been investigated in detail.

In this study, a nanocomposite consisting of three-dimensional reduced graphene oxide (3D-rGO) and plasma-polymerized propargylamine (3D-rGO@PpPG) was prepared and used as a highly sensitive and selective DNA sensor for detecting Hg2+. Given the high density of amino groups in the resultant 3D-rGO@PpPG nanocomposite, thymine-rich and Hg2+-targeted DNA was preferentially immobilized on the fabricated sensor surface via the strong electrostatic interaction between DNA strands and the amino-functionalized nanocomposites, followed by detecting Hg2+ through T–Hg2+–T coordination chemistry between DNA and Hg2+. The results of electrochemical measurements revealed that the anchored amount of DNA strands anchored on the 3D-rGO@PpPG nanofilm surface affects the determination of Hg2+ in aqueous solution. It showed high sensitivity and selectivity toward Hg2+ within concentrations ranging from 0.1 to 200 nM and displayed a low detection limit of 0.02 nM. The new strategy proposed also provides high selectivity of Hg2+ against other interfering metal ions, good stability, and repeatability. The excellent applicability of the developed sensor confirms the potential use of plasma-modified nanofilms for the detection of heavy metal ions in real environmental samples and water.

By combining experiment with molecular simulation, the CO 2 sorption performance of a 2D honeycomb layered coordination polymer, {[Zn 2 (bpydb) 2 (H 2 O) 2 ](DMA) 3 (H 2 O)} n ( 1 ) (bpydb = 4,4′-(4,4′-bipyridine-2,6-diyl) dibenzoate) was systematically investigated. The desolvated 1 not only shows high CO 2 capacity (72.5 cm 3 /g at 273 K and 42.9 cm 3 /g at 298 K) with a moderate high zero-coverage adsorption enthalpy (29.7 kJ/mol), but also exhibits excellent CO 2 /N 2 selectivity around room temperature. To better understand the adsorption behaviors and adsorption sites for CO 2 in 1 , GCMC simulations were carried out, which indicate that the open metal sites between two adjacent layers account for the high CO 2 sorption capacity and strong CO 2 binding ability. Moreover, the thermal stability of 1 was further confirmed by the TGA and VT-PXRD, which indicate that 1 could be thermally stable up to 400 °C.

Two pairs of alkaline earth metal-based MOFs have been synthesized by spontaneous self-assembly reactions of Mg(II) or Ca(II) and two tricarboxylate ligands, H3BTTB and H3TCM (H3BTTB = 4,4′,4′′-[benzene-1,3,5-triyl-tris(oxy)]tribenzoic acid; H3TCM = 4,4′,4′′-{[(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)]tris(oxy)}tribenzoic acid), in different solvent media. The Mg/BTTB assemblies, {[Mg3/2(BTTB)(H2O)(DMF)](DMF)}n (1) (DMF = N,N′-dimethylformamide) and {[Mg3/2(BTTB)(DMAc)2](DMAc)0.5}n (2) (DMAc = N,N′-dimethylacetamide), are prepared in DMF/H2O and DMAc/H2O media, respectively, and feature uniform kgd-type 2D bilayer structures but with different compactness. Meanwhile, two Ca/TCM assemblies, {[Ca5/2(TCM)2(DMF)2(H2O)](Me2NH2)(DMF)2(H2O)}n (3) and {[Ca3(TCM)2(DMAc)3(H2O)2](DMAc)5}n (4), have been achieved in DMF/H2O and DMAc/H2O mixed systems as well. However, compounds 3 and 4 have an enormous structural discrepancy, that is, compound 3 shows a complicated parallel 2D → 3D polycatenaned supramolecular architecture while 4 exhibits a 2-fold interpenetrating sit-type 3D framework. These various coordination patterns evidently illustrate the solvent regulation on the alkaline earth metal-based MOFs. The single-crystal-to-single-crystal structural transformation experiment reveals that the loose kgd-network compound 2 can be converted into the compact isoreticular compound 1 when immersed in DMF for 12 h. However, the reversed conversion cannot be realized. In addition, their thermal stability, gas adsorption, and solid-state fluorescence properties have also been investigated.

Two isomeric Zn(II)-based metal–organic frameworks, {[Zn(CPT)2](NMF)3}n (1) and {[Zn(CPT)2](DMF)0.75}n (2) (HCPT = 4-(4-carboxyphenyl)-1,2,4-triazole, NMF = N-methylformamide, DMF = N,N-dimethylformamide), with the same 4-fold interpenetrated dia topological network have been prepared under solvothermal conditions by employing a bifunctional triazolate–carboxylate organic linker, which show very similar voids but different pore shapes. Thermogravimetry, powder X-ray diffraction, molecular mechanics calculation, and gas sorption studies revealed their different framework stabilities and flexibilities, in which desolvated 1 exhibits temperature-dependent stepwise and hysteretic selective sorption of CO2 over N2 at 195 K, whereas desolvated 2 could adsorb neither CO2 nor N2. Furthermore, the luminescence properties of 1 and 2 were investigated.

By virtue of unique planar [Co6(μ3-OH)4] cluster units, a new microporous isonicotinate-based framework with high thermal and framework stabilities was achieved. The guest-free framework demonstrates high capacity and selectivity for C2H2 relative to CO2 and CH4 at room temperature, which was further understood by GCMC simulation.

The catalytic [5 + 1] annulation/5-exo-cyclization reaction of amidines with diynes is reported herein. This protocol provides highly atom-economical access to fabricate two nitrogen-containing heterocycles in one step with high efficiency and selectivity. Significantly, this reaction represents the first example of using diyne as a one-carbon reaction partner in C–H functionalization. Kinetic isotope effects suggested that the catalytic cycle of this reaction is initiated by the cleavage of the ortho C–H bond in the N-phenyl ring of amidines, which is likely involved in the rate-limiting step. Calculations based on density functional theory (DFT) indicated that C–H activation and the formation of Rh(V) species via 5-exo-cyclization could be vital processes for this cascade transformation.

A new bimetallic Co/Fe-MOF was synthesized and phosphatized to produce a visible-light-active Co/Fe binary metal phosphide embedded in a mesoporous carbon matrix (denoted by CoP/Fe2P@mC). The results of X-ray diffraction and photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy reveal the formation of CoP and Fe2P nanoparticles together with the Co and Fe metallic state. Combining the high electron-hole separation rate of Fe2P@mC, fast electron transfer of CoP@mC, and the strong adsorption of mesoporous carbon, the as-prepared CoP/Fe2P@mC catalyst exhibits substantially enhanced photocatalytic activity toward rhodamine B (RhB) degradation under visible light irradiation. Visible light harvesting efficiency is enhanced by the suitable bandgap structure of the CoP/Fe2P@mC photocatalyst. Moreover, the possible photocatalytic mechanism of CoP/Fe2P@mC toward RhB degradation was proposed on the basis of radical trapping and electron spin resonance results. This finding illustrates a potential utilization of bimetallic MOF-derived metal phosphide as a photocatalyst to remove dye pollutants in the environment.

The self-assembly of a bifunctional organic ligand with a formate-bridged rod-shaped secondary building unit leads to a new microporous metal-organic framework (MOF). This MOF shows a moderately high C

Two-dimensional (2D) zirconium-based metal–organic framework nanosheets embedded with Au nanoclusters (denoted as 2D AuNCs@521-MOF) were prepared via a one-pot method under mild conditions. The optimized 2D AuNCs@521-MOF nanosheets not only possessed high specific surface area, physicochemical stability, and good electrochemical activity but also exhibited strong bioaffinity toward biomolecule-bearing phosphate groups. Consequently, a large amount of cocaine aptamer strands can be immobilized onto the substrate modified by 2D AuNCs@521-MOF nanosheet, further leading to the formation of a constructed biosensitive platform, which can be used to successfully detect cocaine through the specific binding interactions between cocaine and aptamer strands. The results demonstrated that the 2D AuNCs@521-MOF-based aptasensor had high sensitivity for detecting cocaine within the broad concentration range of 0.001–1.0 ng·mL–1 and the low limit of detection of 1.29 pM (0.44 pg·mL–1) and 2.22 pM (0.75 pg·mL–1) as determ...

A custom-designed bifunctional ligand was used to connect an in situ formed Co3(OH) cluster affording a porous metal-organic framework, which represents the first case of ncb-type networks constructed from a single kind of ditopic ligand. Noticeably, the activated MOF shows high volumetric C2H2 uptake and excellent adsorption selectivity for C2H2/CO2 separation at room temperature with a low sorption heat.

A new core-shell nanostructured composite composed of Fe(III)-based metal-organic framework (Fe-MOF) and mesoporous Fe3O4@C nanocapsules (denoted as Fe-MOF@mFe3O4@mC) was synthesized and developed as a platform for determining trace heavy metal ions in aqueous solution. Herein, the mFe3O4@mC nanocapsules were prepared by calcining the hollow Fe3O4@C that was obtained using the SiO2 nanoparticles as the template, followed by composing the Fe-MOF. The Fe-MOF@mFe3O4@mC nanocomposite demonstrated excellent electrochemical activity, water stability and high specific surface area, consequently resulting in the strong biobinding with heavy-metal-ion-targeted aptamer strands. Furthermore, by combining the conformational transition interaction, which is caused by the formation of the G-quadruplex between a single-stranded aptamer and high adsorbed amounts of heavy metal ions, the developed aptasensor exhibited a good linear relationship with the logarithm of heavy metal ion (Pb2+ and As3+) concentration over the broad range from 0.01 to 10.0nM. The detection limits were estimated to be 2.27 and 6.73 pM toward detecting Pb2+ and As3+, respectively. The proposed aptasensor showed good regenerability, excellent selectivity, and acceptable reproducibility, suggesting promising applications in environment monitoring and biomedical fields.

Metal–organic frameworks (MOFs) represent a promising class of porous materials. However, MOFs show poor processability that impedes their full potential in applications. This work develops a composite strategy to skillfully load MOFs on a polymer plate to afford processability for these powder materials. A predesigned mesoporous MOF with active −NH2 groups around the pore walls was prepared and its copolymerization with the −NCO groups of macromonomers (polyurethane acrylate) could be facilely induced by an initiator under mild conditions. Notably, the target MOF–polymer composite is transparent, elastic, and shows enhanced Fe3+ detection compared with that of the individual MOF functional component. This result can be ascribed to the synergistic effect of the composite with newly formed chemical bonds between the MOF particle and polymer matrix.

Herein, we report the synthesis of a new mixed-linker Zn(II)-based metal-organic framework (MOF), {[Zn2(atz)2(bpydb)](DMA)8}n (1) (atz = deprotonated 3-amino-1,2,4-triazole, bpydb = deprotonated 4,4'-(4,4'-bipyridine-2,6-diyl) dibenzoic acid, DMA = N,N-dimethylacetamide), through symmetry modulation of a triazole ligand. The desymmetrized triazole linkers not only bond to the Zn(II) ions to result in a new helical Zn-triazolate chain building unit but also lead to the formation of a highly porous framework (N2 uptake: 617 cm(3)/g; BET surface area: 2393 m(2)/g) with 1D helical channels. The adsorption properties of desolved 1 were investigated by H2, C2H2, CO2, and CH4 sorption experiments, which showed that 1 exhibited high uptake capacity for H2 at 77 K and C2H2 around room temperature. More importantly, the high C2H2 uptake capacity but low binding energy makes this MOF a promising candidate for effective C2H2 capture from C2H2/CO2 and C2H2/CH4 mixed gases with low regenerative energy cost. In addition, 1 shows potential application for the luminescence sensing of small aromatic molecules picric acid (PA) and p-xylene (PX).

Two isostructural Co

A moisture-stable three-dimensional (3D) metal-organic framework (MOF), {(Me2NH2)[Zn2(bpydb)2(ATZ)](DMA)(NMF)2}n (1, where bpydb = 4,4'-(4,4'-bipyridine-2,6-diyl)dibenzoate, ATZ = deprotonated 5-aminotetrazole, DMA = N,N-dimethylacetamide, and NMF = N-methylformamide), with uncoordinated N-donor sites and charged framework skeleton was fabricated. This MOF exhibits interesting structural dynamic upon CO2 sorption at 195 K and high CO2/N2 (127) and CO2/CH4 (131) sorption selectivity at 298 K and 1 bar. Particularly, its CO2/CH4 selectivity is among the highest MOFs for selective CO2 separation. The results of Grand Canonical Monte Carlo (GCMC) simulation indicate that the polar framework contributes to the strong framework-CO2 binding at zero loading, and the tetrazole pillar contributes to the high CO2 uptake capacity at high loading. Furthermore, the solvent-responsive luminescent properties of 1 indicate that it could be utilized as a fluorescent sensor to detect trace amounts of nitrobenzene in both solvent and vapor systems.

Incorporating the in situ formed size-matching molecular building blocks (MBBs) into the open channels will remarkably improve the robustness and gas sorption performance of an evacuated metal–organic framework. As a result, such MBBs can transfer the open metal sites from the framework walls to the channel centers and separate the large channels into multiple smaller voids, leading to a molecular sieving effect and high-performance gas-separation of the modified material.

A promising alternative strategy for designing mesoporous metal-organic frameworks (MOFs) has been proposed, by modifying the symmetry rather than expanding the length of organic linkers. By means of this approach, a unique MOF material based on the target [Zn8(ad)4] (ad = adeninate) clusters and C3-symmetric organic linkers can be obtained, with trigonal microporous (ca., 0.8 nm) and hexagonal mesoporous (ca., 3.0 nm) 1D channels. Moreover, the resulting 446-MOF shows distinct reactivity to transition and lanthanide metal ions. Significantly, the transmetalation of Co(II) or Ni(II) on the Zn(II) centers in 446-MOF can enhance the sorption capacities of CO2 and CH4 (16-21%), whereas the impregnation of Eu(III) and Tb(III) in the channels of 446-MOF will result in adjustable light-emitting behaviors.

Two-dimensional (2D) zirconium-based metal-organic framework (denoted as 521-MOF) nanosheets with the thickness of 6.0–7.5 nm were prepared with the aid of polyvinyl pyrrolidone (PVP) under the mild conditions and low temperature (50 °C). Since 521-MOF nanosheets displayed good electrochemical activity, high surface area, and strong affinity interaction between the MOF and the oligonucleotides sequences, they can impel the immobilization of large amounts of aptamer strands when applied as a platform of biosensor. As a result, the developed aptasensor exhibited sensitive bio-recognition for the cancer determination marker protein, mucin 1 (MUC1). The combination of electrochemical techniques and surface plasmon resonance spectroscopy (SPR) was performed to probe the kinetic processes of the aptamer immobilization and the MUC1 detection. The consistency between different determination approaches was observed, in which the developed aptasensor based on 521-MOF nanosheets exhibits pretty high sensitivity for detecting MUC1 with a low detect limit of 0.12 and 0.65 pgml−1 deduced from electrochemical impedance spectroscopy and SPR, respectively, within the broad concentration range of MUC1 from 0.001 to 0.5 ngml−1. Simultaneously, a comparable affinity constant, K a, was derived from EIS and SPR, which also demonstrates that this new biosensing strategy has high selectivity, stability, reproducibility, and good applicability for the MUC1 detection in the human serum. The present finding indicates that the synthesized 521-MOF nanosheets can be employed in the fields of the biosensing or biomedical diagnosis and explored for different kinds of biosensors.