Pyrene-based Metal-organic Frameworks Research Articles

Pyrene-Based Metal-Organic Frameworks with Coordination-Enhanced Electrochemiluminescence for Fabricating a Biosensing Platform.

Enhancing the electrochemiluminescence (ECL) properties of polycyclic aromatic hydrocarbons (PAHs) is a significant topic in the ECL field. Herein, we elaborately chose PAH derivative luminophore 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) as the organic ligand to synthesize a new Ru-complex-free ECL-active metal-organic framework Dy-TBAPy. Interestingly, Dy-TBAPy exhibited a more brilliant ECL emission and higher ECL efficiency than H4TBAPy aggregates. On the one hand, TBAPy luminophores were assembled into rigid MOF skeleton via coordination bonds, which not only enlarged the distance between pyrene cores to eliminate the aggregation-caused quenching (ACQ) effect but also obstructed the intramolecular motions of TBAPy to diminish the nonradiative relaxation, thus realizing a remarkable coordination-enhanced ECL. On the other hand, the ultrahigh porosity of Dy-TBAPy was beneficial to the diffusion of electrons, ions, and coreactant (S2O82-) in the skeleton, which efficiently boosted the excitation of interior TBAPy luminophores and led to a high utilization ratio of TBAPy, further improving ECL properties. More intriguingly, the ECL intensity of the Dy-TBAPy/S2O82- system was about 4.1, 87.0-fold higher than those of classic Ru(bpy)32+/TPrA and Ru(bpy)32+/S2O82- systems. Considering the aforementioned fabulous ECL performance, Dy-TBAPy was used as an ECL probe to construct a supersensitive ECL biosensor for microRNA-21 detection, which showed an ultralow detection limit of 7.55 aM. Overall, our study manifests that coordinatively assembling PAHs into MOFs is a simple and practicable way to improve ECL properties, which solves the ACQ issue of PAHs and proposes new ideas for developing highly efficient Ru-complex-free ECL materials, therefore providing promising opportunities to fabricate high-sensitivity ECL biosensors.

Adsorption in Pyrene-Based Metal-Organic Frameworks: The Role of Pore Structure and Topology.

Pore topology and chemistry play crucial roles in the adsorption characteristics of metal-organic frameworks (MOFs). To deepen our understanding of the interactions between MOFs and CO2 during this process, we systematically investigate the adsorption properties of a group of pyrene-based MOFs. These MOFs feature Zn(II) as the metal ion and employ a pyrene-based ligand, specifically 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy). Including different additional ligands leads to frameworks with distinctive structural and chemical features. By comparing these structures, we could isolate the role that pore size, the presence of open-metal sites (OMS), metal-oxygen bridges, and framework charges play in the CO2 adsorption of these MOFs. Frameworks with constricted pore structures display a phenomenon known as the confinement effect, fostering stronger MOF-CO2 interactions and higher uptakes at low pressures. In contrast, entropic effects dominate at elevated pressures, and the MOF's pore volume becomes the driving factor. Through analysis of the CO2 uptakes of the benchmark materials ─some with narrower pores and others with larger pore volumes─it becomes evident that structures with narrower pores and high binding energies excel at low pressures. In contrast, those with larger volumes perform better at elevated pressures. Moreover, this research highlights that open-metal sites and inherent charges within the frameworks of ionic MOFs stand out as CO2-philic characteristics.

TEMPO radically expedites the conversion of sulfides to sulfoxides by pyrene-based metal-organic framework photocatalysis

Metal-organic frameworks (MOFs) are well-documented for visible light photocatalysis because of their tailorable structures and tunable absorptions through organic linkers. By employing a highly conjugated linker, 4,4’,4’’,4’’’-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid, the optical absorption of the MOF NU-1100 is effectively tuned to visible light below 600 nm region. Under green light irradiation, NU-1100 triggers charge separation and modulates electron transfer from the linkers to the Zr6O4(OH)412+ clusters, driving the oxidation of sulfides to sulfoxides. Notably, adding a redox mediator radically expedites the oxidation of sulfides by NU-1100 photocatalysis, TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) and 4-carboxy-TEMPO. At least 2.7 and 5.2 times of conversions of phenyl methyl sulfide are achieved by NU-1100 photocatalysis with TEMPO and 4-carboxy-TEMPO, respectively. A series of characterizations illustrate that 4-carboxy-TEMPO is adsorbed onto the exterior surface of Zr6O4(OH)412+ clusters of NU-1100 to mediate hole transfer and achieve higher charge transfer efficiency. Mechanistic studies indicate that superoxide is the essential reactive oxygen species and that the oxidation of sulfides is driven by an electron transfer pathway. This study demonstrates the integration of redox mediators with MOFs can drive more efficient visible light photocatalytic reactions.

Nanoporous Pyrene-Based Metal–Organic Frameworks for Fluorescence Screening and Discrimination of Sulfonamide Antibiotics

Nanoporous Pyrene-Based Metal–Organic Frameworks for Fluorescence Screening and Discrimination of Sulfonamide Antibiotics

Stable Pyrene-Based Metal-Organic Framework for Cyclization of Propargylic Amines with CO2 and Detection of Antibiotics in Water.

A pyrene-based metal-organic framework, Cd2(PTTB)(H2O)2 (WYU-11), was synthesized from the tetracarboxylic pyrene ligand H4PTTB (H4PTTB = 1,3,6,8-tetrakis(3-carboxyphenyl)pyrene) and Cd(NO3)2·4H2O. Powder X-ray diffraction analysis discloses that the framework is stable in acid, base, and various organic solvent environments. WYU-11 shows excellent catalytic performance on the cyclization reaction of propargylic amines with CO2 into 2-oxazolidinones under mild conditions (60 °C, atmospheric CO2). 1H NMR studies unveiled that WYU-11 and 1,1,3,3-tetramethylguanidine (TMG) can synergistically activate the propargylic amine substrate and promote the reaction. Importantly, WYU-11 represents a rare example of noble metal-free heterogeneous catalyst that can catalyze the cyclization of CO2 with propargylic amines. In addition, by virtue of the excellent water stability and luminescence properties, WYU-11 shows excellent detection performance for sulfathiazole (STZ) and ornidazole (ODZ) in water. Investigation reveals that the coexistence of photoinduced electron transfer and internal filtering effect could reasonably explain the luminescence quenching of WYU-11 by the antibiotics.

Aggregation-induced enhancement of pyrene-based metal-organic framework as a new electrochemiluminescence emitter for ultrasensitive detection of sulfadimethoxine

In this study, a signal-on electrochemiluminescence (ECL) aptasensor for ultrasensitive detection of sulfadimethoxine (SDM) was constructed based on a competitive aptamer strategy. Specifically, cerium-metal-organic framework (Ce-MOF) with large specific surface area and excellent electrical conductivity was combined with gold nanoparticles (AuNPs) to form a substrate, followed by the immobilisation of double-stranded DNA (dsDNA) via AuN bonds. In the presence of SDM, the aptamer tended to form an aptamer-SDM complex, which caused dsDNA to dissociate. After release of the aptamer, the capture probe (CP) combined with the tracer label to enhance the ECL signal. As expected, the prepared sensor displayed an ideal linear response range from 10.0 fg mL−1 to 100 ng mL−1 with a limit of detection (LOD) of 1.28 fg mL−1 and successfully detected SDM in milk and quality control samples.

Sulfonation of pyrene-based metal–organic framework for the encapsulation of chiral organocatalyst and application in asymmetric aldol addition

Encapsulation of bulky chiral chiral organocatalysts into metal-organic frameworks (MOFs) is a challenge because of difficult control on the crystallinity of MOFs. Herein, Zr6(μ3-OH)8(OH)8TBAPy)2 (NU-1000) with is sulfonated at − 30 °C by ClSO3H at low concentration, and then bulky cinchona alkaloid-derived chiral primary amines, 9-amino (9-deoxy)epi-quinine (QNNH2) and 9-amino(9-deoxy) epi-cinchonidine (CDNH2), are anchored to NU-1000 via acid-base reaction. At a molar ratio of QNNH2/-SO3H = 0.96, NU-1000-supported QNNH2 with high surface area (677 m2 g−1), large pore volume (0.48 cc g−1), and most probable pore size of 3.0 nm shows high yields (86–95 %) with good to excellent diasteroselectivities (anti/syn = 81/19–93/3) and enantioselectivies (89–96 %ee) in the asymmetric aldol reaction of cyclohexanone with benzaldehydes bearing electron-withdrawing groups (-NO2 and -CN) at o, m, p-positions. This work develops an effective strategy for anchoring bulky chiral organocatalyst into the porous framework of MOFs, broadening the application of MOFs in heterogeneous asymmetric organocatalysis.

Dimension-dependent fluorescence emission and photoelectric performances of a 3D pyrene-based metal−organic framework

A pyrene-based metal-organic framework [Ca2 (TBAPy) (μ2-OH2)2] (1, H4TBAPy ​= ​1,3,6,8-tetrakis (p-benzoic acid)pyrene), directed by ionic liquids, has been synthesized. 1 has non-interpenetrated open 3D framework constructed by infinite rod-shaped Ca-carboxylate secondary building units (SBUs) and rectangle TBAPy ligands. The temperature-dependent fluorescence emission clearly shows that 1 can maintain the excimer fluorescence emission in a broad temperature range (20–450 ​K). Photoelectronic measurements reveal that the average light photocurrent density (Ilight) of 1 is apparently higher than that of other 2D TBAPy-based MOFs. The dimension-dependent fluorescence emission and photoelectric performances of several TBAPy-based MOFs were well investigated based on the steric configuration and the interplanar distance of the coupled TBAPy ligands, as well as the photocurrent conduction path.

Exchange controlled triplet fusion in metal–organic frameworks

Triplet-fusion-based photon upconversion holds promise for a wide range of applications, from photovoltaics to bioimaging. The efficiency of triplet fusion, however, is fundamentally limited in conventional molecular and polymeric systems by its spin dependence. Here, we show that the inherent tailorability of metal–organic frameworks (MOFs), combined with their highly porous but ordered structure, minimizes intertriplet exchange coupling and engineers effective spin mixing between singlet and quintet triplet–triplet pair states. We demonstrate singlet–quintet coupling in a pyrene-based MOF, NU-1000. An anomalous magnetic field effect is observed from NU-1000 corresponding to an induced resonance between singlet and quintet states that yields an increased fusion rate at room temperature under a relatively low applied magnetic field of 0.14 T. Our results suggest that MOFs offer particular promise for engineering the spin dynamics of multiexcitonic processes and improving their upconversion performance.

Pore size effect of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene-based metal-organic frameworks for enhanced SF6 adsorption with high selectivity

Anthropogenic greenhouse gas emission poses as serious threat to our environment and it is therefore of utmost importance that efficient systems are developed to mitigate these issues. SF6, in particular, has attracted more attention in recent years due to its global warming potential which severely exceeds that of CO2. In this study we present the SF6 sorption properties of four highly porous 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene-based (TBAPy4−) metal-organic frameworks containing either ytterbium(III), thulium(III), cerium(III), or hafnium(IV). These MOFs can be synthesized with high crystallinity in as little as 5 h and were found to have good SF6 uptakes due to their suitable pore size. The SF6 uptake of the Yb-TBAPy MOF reached 2.33 mmol g−1 with high Henry's law SF6-over-N2 selectivity of ∼80 at 1 bar and 293 K. The TBAPy-MOFs were also found to have good chemical stability and good cyclic SF6 sorption stability with fast SF6 uptake. These TBAPy-MOFs possesses many of the properties desired for an efficient SF6 sorbent and may be suitable sorbents for further development, including sorbent processing for industrial applications.

Topology- and Guest-Dependent Photoelectric Conversion of 2D Anionic Pyrene-Based Metal–Organic Framework

Topology- and Guest-Dependent Photoelectric Conversion of 2D Anionic Pyrene-Based Metal–Organic Framework

Sulfonation of Pyrene-Based Metal–Organic Framework for the Encapsulation of Chiral Organocatalyst and Application in Asymmetric Aldol Addition

Sulfonation of Pyrene-Based Metal–Organic Framework for the Encapsulation of Chiral Organocatalyst and Application in Asymmetric Aldol Addition

Efficient Energy-Transfer-Induced High Photoelectric Conversion in a Dye-Encapsulated Ionic Pyrene-Based Metal-Organic Framework.

The relationship between the aggregation states of pyrene-based linkers and the photoluminescence/photoelectric performance was well studied by the formation of an anionic metal-organic framework, [BMI]2[Mg3(TBAPy)2(H2O)4]·2dioxane, which shows highly enhanced light-harvesting and photoelectric conversion efficiency by the encapsulation of D-π-A cation dyes.

Toward Optimal Photocatalytic Hydrogen Generation from Water Using Pyrene-Based Metal-Organic Frameworks.

Metal–organic frameworks (MOFs) are promising materials for the photocatalytic H2 evolution reaction (HER) from water. To find the optimal MOF for a photocatalytic HER, one has to consider many different factors. For example, studies have emphasized the importance of light absorption capability, optical band gap, and band alignment. However, most of these studies have been carried out on very different materials. In this work, we present a combined experimental and computation study of the photocatalytic HER performance of a set of isostructural pyrene-based MOFs (M-TBAPy, where M = Sc, Al, Ti, and In). We systematically studied the effects of changing the metal in the node on the different factors that contribute to the HER rate (e.g., optical properties, the band structure, and water adsorption). In addition, for Sc-TBAPy, we also studied the effect of changes in the crystal morphology on the photocatalytic HER rate. We used this understanding to improve the photocatalytic HER efficiency of Sc-TBAPy, to exceed the one reported for Ti-TBAPy, in the presence of a co-catalyst.

Two Pyrene-Based Metal-Organic Frameworks for Chemiluminescence.

Fluorescent agents play an important role in the peroxyoxalate chemiluminescence system. However, the effect of different frameworks on chemiluminescence (CL) has not been explored. Herein two pyrene-based metal-organic frameworks (MOFs), [Pb2L]n·2nDMA·2nH2O (1) and [(Ca2L)·(DMF)3]n·2.5nDMF·6nH2O (2) (H4L = 5,5'-(-pyrene-1,6-diyl)-diisophthalic acid; DMA = N,N'-dimethylacetamide; DMF = N,N'-dimethylformamide), have been successfully synthesized and are applied to CL. They both exhibit strong and lasting emission that is visible to the naked eye and is significantly stronger than that of the ligand. More importantly, compared with 2, 1 has notably better CL performance. We infer that the reason may be that 1 has higher stability and larger open channels, which can avoid the aggregation of organic ligands as well as provide an effective pathway for the active substance to diffuse into the channels.

Pyrene-based metal organic frameworks: from synthesis to applications.

Pyrene is one of the most widely investigated aromatic hydrocarbons given to its unique optical and electronic properties. Hence, pyrene-based ligands have been attractive for the synthesis of metal-organic frameworks (MOFs) in the last few years. In this review, we will focus on the most important characteristics of pyrene, in addition to the development and synthesis of pyrene-based molecules as bridging ligands to be used in MOF structures. We will summarize the synthesis attempts, as well as the post-synthetic modifications of pyrene-based MOFs by the incorporation of metals or ligands in the structure. The discussion of promising results of such MOFs in several applications; including luminescence, photocatalysis, adsorption and separation, heterogeneous catalysis, electrochemical applications and bio-medical applications will be highlighted. Finally, some insights and future prospects will be given based on the studies discussed in the review. This review will pave the way for the researchers in the field for the design and development of novel pyrene-based structures and their utilization for different applications.

Sustainable Capture of Aromatic Volatile Organic Compounds by a Pyrene-Based Metal-Organic Framework under Humid Conditions.

The threat posed by the presence of artificial volatile organic compounds (VOCs) in the environment is a widely acknowledged fact, both for environmental issues and human health concerns. Ever-increasing production requires the continuous development of technologies toward the removal of these substances. In recent years, metal-organic frameworks (MOFs) have shown a great promise toward the capture of VOCs, but their stability in humid conditions still remains a major challenge, thus hindering their widespread development. To tackle this obstacle, we designed a 3-dimensional and porous MOF, named SION-82, for the capture of small aromatic VOCs, relying solely on π-π interactions. SION-82 captures benzene efficiently (107 mg/g) in dry conditions, and no uptake decrease was observed in the presence of high relative humidity for at least six cycles. Unlike HKUST-1 and MOF-74(Co), SION-82 possesses two vital characteristics toward sustainable benzene capture under humid conditions: moisture stability and reusability. In addition, SION-82 captures benzene under humid conditions more efficiently compared to the hydrolytically stable UiO-66, highlighting the impact of having an active site for benzene capture that is not affected by water. SION-82 can additionally capture other aromatic VOCs, showing pyridine and thiophene uptake capacities of 140 and 160 mg/g, respectively.

Single crystal structure and photocatalytic behavior of grafted uranyl on the Zr-node of a pyrene-based metal–organic framework

The zirconium MOF NU-1000 was post-synthetically modified through solvothermal deposition to include the uranyl ion and characterizedviasingle-crystal X-ray diffraction; photo-oxidation was also performed.

Air oxidation of sulfur mustard gas simulants using a pyrene-based metal-organic framework photocatalyst.

We demonstrate a microporous metal–organic framework NU-400 based on a 2,7-disubstituted pyrene linker as a highly efficient photosensitizer for generating singlet oxygen and subsequent oxidative degradation of chemical warfare agents (CWAs). The high activity of NU-400 permits photocatalytic conversion of the 2-chloroethyl ethyl sulfide (CEES) mustard gas simulant into a benign sulfoxide derivative, in air, with less than 15 minutes’ half-life. This is a considerable improvement to NU-1000, based on a 1,3,6,8-tetrasubstituted pyrene unit, demonstrating how variation of the substitution pattern of a metal–organic framework linker permits modification of its photoactive behavior.

Highly Dense Packing of Chromophoric Linkers Achievable in a Pyrene-Based Metal-Organic Framework for Photoelectric Response.

Highly dense packing of chromophoric linkers is achieved in a novel pyrene-based metal-organic framework (MOF), [Zn(TBAPy)1/2(H2O)2], induced by an ionic liquid. This MOF displays a quick response to visible-light irradiation (photocurrent density of up to 4.492 μA cm-2) and is capable of repetitive on-off photocurrent switching with a large on-off ratio (37.55).