Hafnium-Based Metal Organic Framework Research Articles

Analysis of okadaic acid using electrochemiluminescence imaging on microfluidic biosensing chip

The sensitivity and specificity of electrochemiluminescence (ECL)-based biosensor directly rely on the property of luminophor, the type of sensing carriers and the effectiveness of signal amplification used in the sensor design, which poses a major challenge to manage these elements simultaneously. In this work, an aggregation-induced electrochemiluminescence (AIECL) microfluidic sensing chip using 4′,4″,4‴,4‴'-(ethene-1,1,2,2-tetrayl)tetrabiphenyl-4-carboxylic acid (TPE)-derived hafnium-based metal-organic framework (Hf-MOF) as emitter was developed. An easily overlooked marine pollutant, okadaic acid (OA) with different concentrations ranging from 5.00 ng/mL to 1.50 × 104 ng/mL at the electrode is visualized imaging benefit from high luminescence efficiency of Hf-MOF coupled the rolling circle amplification strategy assisted by trans-cleavage activity of CRISPR/Cas12a. These highlights will solve the long-lasting task in the accurate analysis of small molecule pollutants, which can be able to provide more worthy reference solution about construction of novel ECL luminophor and signal extraction of low-abundance disease-related biomarkers.

Cooperative photocatalysis of hafnium-based metal–organic framework and TEMPO for selective oxidation of sulfides

Cooperative photocatalysis of hafnium-based metal–organic framework and TEMPO for selective oxidation of sulfides

A phase 1 dose-escalation study of RiMO-301 with palliative radiation in advanced tumors.

2527 Background: Nanoscale metal−organic frameworks (MOFs) are a new class of organic−inorganic hybrid nanomaterials constructed from metal centers and organic ligands. Preclinical studies have shown that nanoscale MOFs can enhance the antitumor effects of ionizing radiation via a unique radiotherapy-radiodynamic therapy mode of action, and MOFs plus radiation can enhance the immunotherapeutic effects of immune checkpoint inhibitors. RiMO-301 is a hafnium-based MOF which enhances radiotherapy and checkpoint blockade immunotherapy without showing systemic toxicity in preclinical models. RiMO-301 is the first MOF to enter clinical trials on human patients. Methods: This is a multicenter, open-label, first-in-human dose-escalation phase I trial of RiMO-301 [NCT03444714]. The primary objective is to determine the maximum tolerated dose (MTD) of locally injected RiMO-301 with or without the PD-1 inhibitor pembrolizumab in patients treated with concurrent palliative doses of radiation (20 Gy in 5 fractions or 30 Gy in 10 fractions) using a 3+3 design. The MTD is defined as the dose associated with dose-limiting toxicity (DLT) in less than 33% of patients. The secondary objective is to evaluate antitumor response (objective response rate, ORR) using RECIST and itRECIST criteria. Results: A total of 25 patients were enrolled and treated with escalating doses of RiMO-301 (relative to tumor volumes). No protocol defined DLT was reported. The observed possibly treatment related adverse events included mild dermatitis radiation, mild dysgeusia, diarrhea, mild hypotension (30 days post treatment) and mild dizziness (30 days post treatment). One patient each experienced a Grade 2 alanine aminotransferase increase 45 days post treatment, a Grade 2 dry mouth, and a Grade 3 pain at the injection site. Nineteen patients were evaluable, with 13 and 6 patients, respectively, for RiMO-301 without and with pembrolizumab treatments. By itRECIST criteria, RiMO-301 without pembrolizumab demonstrated 38.5% (5/13) ORR (1 complete response and 4 partial responses) with 2 additional patients experiencing 20-30% tumor size reduction. RiMO-301 with pembrolizumab exhibited 66.7% (4/6) ORR with the 2 remaining patients showing 15-20% tumor size reduction. Preliminary pharmacokinetic analysis indicated that the hafnium concentrations in the systemic circulation were either below or barely above the level of detection. Conclusions: RiMO-301 with or without pembrolizumab was well tolerated and demonstrated promising signs of efficacy in patients with advanced tumors when treated with concurrent palliative radiotherapy. The results support the use of RiMO-301 as a potential radio-enhancer and will prompt further phase 2 studies in the development of RiMO-301 for patients undergoing radiotherapy. Clinical trial information: NCT03444714 .

Synergistic Effects of Lewis Acid-Base Pair Sites─Hf-MOFs with Functional Groups as Distinguished Catalysts for the Cycloaddition of Epoxides with CO2.

The incorporation of Lewis acid-base sites in catalysts has been considered as a significant approach to fabricating bifunctional catalysts with efficient catalytic activity for CO2 fixation. In this paper, a series of Hafnium-based metal-organic frameworks (Hf-MOFs), NU-912(Hf) and NU-912-X(Hf)-X (X = -NH2, -Br, -CN, and -I) derivatives assembled by Lewis acidic Hf6(μ3-O)4(μ3-OH)4(H2O)4(OH)4 (Hf6) clusters and Lewis base-attached organic linkers, are successfully synthesized by a facile ligand functionalization method. These isostructural Hf-MOFs, which exhibit diamond channels of 1.3 nm diameter, great chemical stability, and CO2 adsorption capacity, have been evaluated as catalysts for the CO2 cycloaddition reaction with epoxides. Catalytic experiments reveal that the micropore environments of these MOFs have an outstanding impact on catalytic activity. Remarkably, NU-912(Hf)-I serves as an efficient heterogeneous catalyst for this catalytic reaction under mild conditions due to the high density of Lewis acid Hf6 cluster centers and strong Lewis base functional groups, surpassing most of the reported MOF-based catalysts.

Nanoscale Hafnium Metal-Organic Frameworks Enhance Radiotherapeutic Effects by Upregulation of Type I Interferon and TLR7 Expression.

Recent preclinical and clinical studies have highlighted the improved outcomes of combination radiotherapy and immunotherapy. Concurrently, the development of high-Z metallic nanoparticles as radiation dose enhancers has been explored to widen the therapeutic window of radiotherapy and potentially enhance immune activation. In this study, folate-modified hafnium-based metal-organic frameworks (HfMOF-PEG-FA) are evaluated in combination with imiquimod, a TLR7 agonist, as a well-defined interferon regulatory factor (IRF) stimulator for local antitumor immunotherapy. The enhancement of radiation dose deposition by HfMOF-PEG-FA and subsequent generation of reactive oxygen species (ROS) deregulates cell proliferation and increases apoptosis. HfMOF-PEG-FA loaded with imiquimod (HfMOF-PEG-FA@IMQ) increases DNA double-strand breaks and cell death, including apoptosis, necrosis, and calreticulin exposure, in response to X-ray irradiation. Treatment with this multipronged therapy promotes IRF stimulation for subsequent interferon production within tumor cells themselves. The novel observation is reported that HfMOF itself increases TLR7 expression, unexpectedly pairing immune agonist and receptor upregulation in a tumor intrinsic manner, and supporting the synergistic effect observed with the γH2AX assay. T-cell analysis of CT26 tumors following intratumoral administration of HfMOF-PEG-FA@IMQ with radiotherapy reveals a promising antitumor response, characterized by an increase in CD8+ and proliferative T cells.

A stable ultra-microporous hafnium-based metal–organic framework with high performance for CO2 adsorption and separation

A double walled hafnium-based metal–organic framework with ultra-microporous structure was successfully constructed and displayed high chemical stability and commendable CO2 adsorption and separation ability.

Boosting Photocatalytic Hydrogen Peroxide Production from Oxygen and Water Using a Hafnium-Based Metal–Organic Framework with Missing-Linker Defects and Nickel Single Atoms

Boosting Photocatalytic Hydrogen Peroxide Production from Oxygen and Water Using a Hafnium-Based Metal–Organic Framework with Missing-Linker Defects and Nickel Single Atoms

Friedlander condensation reaction catalysed by hafnium-based metal-organic framework

Heterogeneous catalysis using metal-organic frameworks (MOFs) is one of the attractive fields in recent years because MOFs offer tuneable properties and a broad range of active sites. In this context, synthesis and characterization of UiO-66(Hf)-(NHCOMe)2 (1) and its activated form (1′) are reported. The catalytic behavior of 1′ was investigated in the Friedlander condensation between 2-aminoacetophenone with acetylacetone under mild reaction conditions. The reaction between 2-aminoacetophenone and acetylacetone in the presence of 1′ afforded a quantitative yield of the desired product. On the other hand, the stability of 1′ was also examined by reusing the solid catalyst and characterizing the recovered solid catalyst by powder XRD, FESEM, 1H NMR, 13C NMR, ATR-IR and BET methods. These combined data indicate that the solid catalyst undergoes a structural change by losing its catalytic activity in the first reuse and becomes deactivated. Although no significant changes were observed between the fresh and the recovered solid by powder XRD, FESEM, 1H NMR, 13C NMR, ATR-IR, the significant decrease in BET surface area of the recovered solid suggests the possible pore blocking by the products.

Comparative Studies on the Proton Conductivities of Hafnium-Based Metal-Organic Frameworks and Related Chitosan or Nafion Composite Membranes.

Hafnium (Hf)-based UiO-66 series metal-organic frameworks (MOFs) have been widely studied on gas storage, gas separation, reduction reaction, and other aspects since they were first prepared in 2012, but there are few studies on proton conductivity. In this work, one Hf-based MOF, Hf-UiO-66-fum showing UiO-66 structure, also known as MOF-801-Hf, was synthesized at room temperature using cheap fumaric acid as the bridging ligand, and then imidazole units were successfully introduced into MOF-801-Hf to obatin a doped product, Im@MOF-801-Hf. Note that both MOF-801-Hf and Im@MOF-801-Hf demonstrate excellent thermal, water, and acid-base stabilities. Expectedly, the maximum proton conductivity (σ) of Im@MOF-801-Hf (1.46 × 10-2 S·cm-1) is nearly 4 times greater than that of MOF-801-Hf (3.98 × 10-3 S·cm-1) under 100 °C and 98% relative humidity (RH). To explore their possible practical application value, we doped them into chitosan (CS) or Nafion membranes as fillers, namely, CS/MOF-801-Hf-X, CS/Im@MOF-801-Hf-Y, and Nafion/MOF-801-Hf-Z (X, Y, and Z are the doping percentages of MOF in the membrane, respectively). Intriguingly, it was found that CS/MOF-801-Hf-6 and CS/Im@MOF-801-Hf-4 indicated the highest σ values of 1.73 × 10-2 and 2.14 × 10-2 S·cm-1, respectively, under 100 °C and 98% RH and Nafion/MOF-801-Hf-9 also revealed a high σ value of 4.87 × 10-2 S·cm-1 under 80 °C and 98% RH, which showed varying degrees of enhancement compared to the original MOFs or pure CS and Nafion membranes. Our study illustrates that these Hf-based MOFs and related composite membranes offer great potential in electrochemical fields.

Hafnium-Based Metal-Organic Framework Nanoparticles as a Radiosensitizer to Improve Radiotherapy Efficacy in Esophageal Cancer.

Radiotherapy is one of the most widely used clinical treatments for tumors, but it faces limitations, such as poor X-ray retention at the tumor site. The use of radiosensitizers containing high Z elements is an effective way to enhance X-ray absorption. Here, we demonstrate a simple one-step method for the synthesis of UiO-66-NH2(Hf) metal–organic framework nanoparticles for use as radiosensitizers in radiotherapy. The UiO-66-NH2(Hf) nanoparticles had a diameter of less than 100 nm and were stable in the physiological environment. UiO-66-NH2(Hf) induced apoptosis by enhancing X-ray absorption, as confirmed by in vitro and in vivo experiments. These characteristics make UiO-66-NH2(Hf) a promising radiosensitizer for esophageal cancer radiotherapy.

A hafnium-based metal-organic framework for the entrapment of molybdenum hexacarbonyl and the light-responsive release of the gasotransmitter carbon monoxide

A carbon monoxide-releasing material (CORMA) has been prepared by inclusion of molybdenum hexacarbonyl in a hafnium-based metal-organic framework (MOF) with the UiO-66 architecture. Mo(CO)6 was adsorbed from solution to give supported materials containing 6.0–6.6 wt% Mo. As confirmed by powder X-ray diffraction (PXRD) and SEM coupled with energy dispersive X-ray spectroscopy, neither the crystallinity nor the morphology of the porous host was affected by the loading process. While the general shape of the N2 physisorption isotherms (77 K) did not change significantly after encapsulation of Mo(CO)6, the micropore volume decreased by ca. 20%. Thermogravimetric analysis of the as-prepared materials revealed a weight loss step around 160 °C associated with the decomposition of Mo(CO)6 to subcarbonyl species. Confirmation for the presence of encapsulated Mo(CO)6 complexes was provided by FT-IR and 13C{1H} cross-polarization magic-angle spinning NMR spectroscopies. To test the capability of these materials to behave as CORMAs and transfer CO to heme proteins, the standard myoglobin (Mb) assay was used. While stable in the dark, photoactivation with low-power UV light (365 nm) liberated CO from the encapsulated hexacarbonyl molecules in Mo(6.0)/UiO-66(Hf), leading to a maximum amount of 0.26 mmol CO released per gram of material. Under the simulated physiological conditions of the Mb assay (37 °C, pH 7.4 buffer), minimal leaching of molybdenum occurred, PXRD showed only slight amorphization, and FT-IR spectroscopy confirmed the high chemical stability of the MOF host.

Water-Tolerant DUT-Series Metal-Organic Frameworks: A Theoretical-Experimental Study for the Chemical Fixation of CO2 and Catalytic Transfer Hydrogenation of Ethyl Levulinate to γ-Valerolactone.

A series of highly thermally and hydrolytically stable porous solids with intriguing properties of zirconium- and hafnium-based metal-organic frameworks (MOFs) [Dresden University of Technology (DUT) series] was synthesized. The DUT MOFs were found to be effective catalysts for both epoxide-CO2 cycloaddition reactions and the catalytic transfer hydrogenation (CTH) of ethyl levulinate (EL). In particular, 12-connected DUT-52(Zr) showed higher catalytic activity than eight- and six-connected catalysts in the synthesis of cyclic carbonates as well as in the production of γ-valerolactone (GVL). The secondary building unit connectivity, coexistence of a moderate number of acidic and basic sites, Brunauer-Emmett-Teller surface area, and combined effects of the pores of the MOFs seem to influence the catalytic activity. The reaction mechanism for the DUT-52(Zr)-mediated cycloaddition reaction of CO2 and the CTH reactions were investigated in detail by using periodic density functional theory calculations. To the best of our knowledge, this is the first detailed computational study for the formation of GVL from EL by using MOF as the catalyst. In addition, grand canonical Monte Carlo simulations predicted the strong interaction of CO2 molecules with the DUT-52(Zr) framework. Remarkably, the DUT-series catalysts possess extraordinary tolerance toward water. Further, DUT-52(Zr) is recyclable and is an efficient catalyst for cycloaddition and CTH reactions for at least five uses without obvious reductions in the activity or structural integrity.

Zr and Hf-metal-organic frameworks: Efficient and recyclable heterogeneous catalysts for the synthesis of 2-arylbenzoxazole via ring open pathway acylation reaction

Zirconium- and hafnium-based metal–organic frameworks which constructed by 12-coordinated clusters and 6-coodinated clusters were shown to be highly effective heterogeneous catalysts for the ring opening acylation of benzoxazole to 2-arylbenzoxazole under solvent free conditions. Owning the wide opening spaces structures and inherent formate sites, MOFs based on 6-connected Zr6/Hf6 node were able to identify a significantly enhanced yield in Brønsted acid catalyzed reactions under conventional heating and microwave irradiation. In addition, the detailed mechanism of active sites of the ring opening acylation reaction was confirmed by employing of density functional theory (DFT) calculations.

Catalytic conversion of furfuryl alcohol or levulinic acid into alkyl levulinates using a sulfonic acid-functionalized hafnium-based MOF

Biomass conversion using reusable solid acid catalysts are highly desirable to comply with the principles of green chemistry. Here, we report a sulfonic acid-functionalized hafnium-based metal-organic framework (MOF), UiO-66(Hf)-SO3H, as an efficientsolid acidcatalyst for the alcoholysis of furfuryl alcohol (FA) andesterification of levulinic acid (LA) affording alkyl levulinates (ALs). Among the as prepared UiO-66 based MOFs(UiO-66(Hf), UiO-66(Hf)-NH2, UiO-66(Hf)-SO3H and UiO-66(Zr)-SO3H), UiO-66(Hf)-SO3H holds highest Brønsted acidity and therefore exhibits excellent catalytic activity towards production of ALs. The highest Brønsted acidity in UiO-66(Hf)-SO3His the result of the covalently bound sulfonic acid groups present inorganic linkers along with the ligated hydroxyl groups (Hf-μ3-OH) to the Hf metal clusters.

Visible-light harvesting pyrene-based MOFs as efficient ROS generators.

The utilization of reactive oxygen species (ROS) in organic transformations is of great interest due to their superior oxidative abilities under mild conditions. Recently, metal-organic frameworks (MOFs) have been developed as photosensitizers to transfer molecular oxygen to ROS for photochemical synthesis. However, visible-light responsive MOFs for oxygen activation remains scarce. Now we design and synthesize two porous MOFs, namely, PCN-822(M) (M = Zr, Hf), which are constructed by a 4,5,9,10-(K-region) substituted pyrene-based ligand, 4,4',4'',4'''-((2,7-di-tert-butylpyrene-4,5,9,10-tetrayl)tetrakis(ethyne-2,1-diyl))-tetrabenzoate (BPETB4-). With the extended π-conjugated pyrene moieties isolated on the struts, the derived MOFs are highly responsive to visible light, possessing a broad-band adsorption from 225-650 nm. As a result, the MOFs can be applied as efficient ROS generators under visible-light irradiation, and the hafnium-based MOF, PCN-822(Hf), can promote the oxidation of amines to imines by activating molecular oxygen via synergistic photo-induced energy and charge transfer.

Hf-based metal–organic frameworks as acid–base catalysts for the transformation of biomass-derived furanic compounds into chemicals

Hafnium-based metal–organic frameworks are promising catalysts for upgrading biomass derivatives via an aldol condensation reaction.

Catalytic Transfer Hydrogenation of Biomass-Derived Carbonyls over Hafnium-Based Metal-Organic Frameworks.

A series of highly crystalline, porous, hafnium-based metal-organic frameworks (Hf-MOFs) have been shown to catalyze the transfer hydrogenation reaction of levulinic ester to produce γ-valerolactone by using isopropanol as a hydrogen donor. The results are compared with their zirconium-based counterparts. The role of the metal center in Hf-MOFs has been identified and reaction parameters optimized. NMR studies using isotopically labeled isopropanol provide evidence that the transfer hydrogenation occurs through a direct intermolecular hydrogen transfer route. The catalyst, Hf-MOF-808, can be recycled several times with only a minor decrease in catalytic activity. The generality of the procedure has been demonstrated by accomplishing the transformation with aldehydes, ketones, and α,β-unsaturated carbonyl compounds. The combination of Hf-MOF-808 with the Brønsted-acidic Al-Beta zeolite gives the four-step one-pot transformation of furfural to γ-valerolactone in good yield of 75 %.

Fast and scalable synthesis of uniform zirconium-, hafnium-based metal-organic framework nanocrystals.

Metal-organic frameworks based on zirconium or hafnium possess tantalizing commercial prospects due to their high stability but require a long reaction time to form crystals. The fast synthesis of uniform Zr-, Hf-MOF nanocrystals at scale is of key importance in the potential commercial application of MOFs. In this work, we have developed a versatile strategy through controlling the hydrolysis and nucleation of metal salts in the presence of acetic acid and water; up to 24 grams of UiO-66-NH2 nanocrystals with a uniform octahedron could be synthesized within 15 minutes using a one step method. The current synthetic strategy could be extended to other Zr-, Hf-MOF nanocrystals [UiO-66-Fast, UiO-66-(OH)2-Fast, UiO-66-2,6-NDC-Fast, UiO-67-Fast, BUT-12-Fast, PCN-222-Ni-Fast, PCN-222-Co-Fast, Hf-UiO-66-Fast, Hf-UiO-66-NH2-Fast, Hf-UiO-66-(OH)2-Fast, Hf-UiO-66-2,6-NDC-Fast and Hf-BUT-12-Fast]. Significantly, when noble metal nanoparticles (NPs) are introduced into MOF precursors, NPs encapsulated in MOFs with excellent dispersion have also been obtained and show outstanding performance in catalysis. This facile procedure is expected to pave the way to expand the commercial applications of MOFs.

A new superacid hafnium-based metal–organic framework as a highly active heterogeneous catalyst for the synthesis of benzoxazoles under solvent-free conditions

A new superacid Hf-based MOF, termed VNU-11-P-SO4, was used as an efficient heterogeneous catalyst for solvent-free 2-arylbenzoxazole synthesis.

Correction to "A Hafnium-Based Metal-Organic Framework as a Nature-Inspired Tandem Reaction Catalyst".

Supporting Information, CIF file. Upon deposition to the Cambridge Structural Database (CSD), it was noted that the hydrogen atoms on the porphyrin ring of the structure were modeled incorrectly. The appropriate changes have been made, and the structure has been refined to convergence. This does not affect the chemistry reported in the publication but has small effects in the final refinement values, and a new CIF file is provided. The corrected data have also been deposited to the CSD.