Dihydrotetrazine-Functionalized Zirconium-Based Metal-Organic Frameworks for High-Capacity Oil Denitrogenation.

High structural stability, dual organic-inorganic nature, and tunability in chemical functionality are promising characteristics of zirconium-based metal-organic frameworks (Zr-MOFs). These properties assist Zr-MOFs in extending their applications in various fields, especially adsorptive removal of pollutants. In this work, two well-known Zr-MOFs (UiO-66(Zr) and MIL-140(Zr) with the formula ZrO(OH)(BDC), HBDC is benzene 1,4-dicarboxylic acid) were synthesized and decorated with a dihydrotetrazine functional group through postsynthesis linker exchange (PSLE).

Functionalization of Defective Zr Metal-Organic Frameworks for Water Decontamination: Mechanistic Insight into the Competitive Roles of -NH and -SH Sites in Removal of As(III) Species.

Direct removal of trivalent arsenic, As(III), arsenite, or HAsO, is a great challenge in accessing clean sources of water. Different methodologies and materials were applied in this regard, but among them, direct removal of As(III) species using a metal-organic framework (MOF)-based adsorbent shows a great deal of potential. Although some studies were conducted on As(III) removal using MOFs, studies of functional groups are still quite rare.

High Capacity Arsenate Removal from Real Samples Using Dihydrotetrazine Decorated Zirconium-Based Metal-Organic Frameworks.

Zirconium metal-organic frameworks (Zr-MOFs) are potential candidates for decontamination of water resources from harmful pollutants due to their modulable porosity and chemical stability in aqueous solutions. Linker functionalization is an approach for tuning the host-guest chemistry of Zr-MOFs and extends their applications in environmental monitoring. In this work, the structure of UiO-66(Zr) (formulated Zr(OH)O(BDC), BDC = benzene-1,4-dicarboxylate) was functionalized with dihydrotetrazine group via postsynthesis linker exchange (PSLE) method.

Functionalization of Defective Zr-MOFs for Water Decontamination: Mechanistic Insight into the Competitive Roles of -NH and -SH Sites in the Removal of Hg(II) Ions.

Functional metal-organic frameworks (MOFs), especially those based on sulfur and nitrogen atoms, were frequently applied for the removal of Hg(II) ions. However, a systematic study on the cooperative or competitive roles of -SH and -NH functions in the presence of secondary mechanisms (proton transfer and redox) is still rare. In this work, the UiO-66 framework (Zr(OH)O(BDC), BDC = benzene-1,4-dicarboxylate) was decorated with functional monocarboxylate linkers including glycine (Gly), mercaptopropionic acid (Mer), and cysteine (Cys).

Multifunctional Roles of Dihydrotetrazine-Decorated Zr-MOFs in Photoluminescence and Colorimetrism for Discrimination of Arsenate and Phosphate Ions in Water.

The high chemical and structural stabilities of zirconium (Zr)-based metal-organic frameworks (MOFs) in aquatic media make them ideal candidates for wastewater treatment. Rational decoration or Zr-MOFs with functional groups can significantly extend their application in this area. In this work, two well-known Zr-MOFs, UiO-66 and MIL-140-A, were functionalized with dihydrotetrazine function to increase their capability in water treatment.

Redox Metal-Organic Framework for Photocatalytic Organic Transformation: The Role of Tetrazine Function in Radical-Anion Pathway.

Linker functionalization is a practical strategy to extend the applications of metal-organic frameworks (MOFs) in various fields. Here, this strategy is applied to synthesize a tetrazine-functionalized MOF [TMU-34(-2H), formulated [Zn(OBA) (DPT)]·DMF; HOBA and DPT are 4,4'-oxybis(benzoic acid) and 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine] for efficient photocatalytic synthesis of disulfides and benzimidazoles with maximum conversion after 90 and 120 min, respectively. The photocatalytic activity of TMU-34(-2H) originates from the electronic properties of tetrazine function, including absorption in the visible region and photogenerated redox activity.

A Dihydrotetrazine-Functionalized Metal-Organic Framework as a Highly Selective Luminescent Host-Guest Sensor for Detection of 2,4,6-Trinitrophenol.

Pore decoration of metal-organic frameworks (MOFs) with functional groups is a useful strategy to attain high selectivity toward specific analytes, especially in the presence of interfering molecules with similar structures and energy levels, through selective host-guest interactions. In this work, we applied a dihydrotetrazine-decorated MOF, TMU-34, with the formula [Zn(OBA)(HDPT)]·DMF, where HOBA is 4,4'-oxybis(benzoic acid) and HDPT is 3,6-bis(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine, for the highly selective detection of phenolic NACs, especially TNP (94% quenching efficiency, detection limit 8.1 × 10 M, = 182663 mol L), in the presence of other substituted NACs especially -NH-substituted NACs.

Photocatalytic Performance of Perovskite and Metal-Organic Framework Hybrid Material for the Reduction of N to Ammonia.

The orthorhombic phase of KNbO perovskite has been applied for nitrogen (N) photoreduction to ammonia (NH). However, this material suffers from a low surface area and low ammonia production efficiency under UV light irradiation. To eliminate these barriers, we used a metal-organic framework (MOF), named as TMU-5 ([Zn(OBA)(BPDH)]·1.

Phenolic nitroaromatics detection by fluorinated metal-organic frameworks: Barrier elimination for selective sensing of specific group of nitroaromatics.

Many piesce of research have been performed to detect nitroaromatic-compounds (NACs) by metal-organic frameworks (MOFs). Despite extensive studies, there are still significant challenges like selective detection of specific NAC group in presence of other NACs. Here, we have integrated two functionalization strategies through decoration of pore-walls of the MOFs with trifluoromethyl groups and extension in π-conjugated system.

High capacity Hg(II) and Pb(II) removal using MOF-based nanocomposite: Cooperative effects of pore functionalization and surface-charge modulation.

Water pollution by heavy metal ions especially Hg(II) and Pb(II) is one of the most important concerns because of their harmful effects on human health and environment sustainability. Here, we developed FeO@TMU-32 metal-organic framework (MOF)-based nanocomposite by applying pore functionalization and surface-charge modulation strategies. Based on synergic effects of these strategies, FeO@TMU-32 nanocomposite shows very high capacity toward Hg(II) and Pb(II) metal ions.

Function-Structure Relationship in Metal-Organic Frameworks for Mild, Green, and Fast Catalytic C-C Bond Formation.

Tunability in chemical functionality is a promising characteristic of metal-organic frameworks (MOFs), which plays an important role in developing and improving the practical applications of MOFs. Here, we applied this important feature of MOFs to be in line with sustainable development and green chemistry principles through the synthesis of MOF-based heterogeneous organocatalysts. According to our green functionalization strategy, some isostructural MOFs (azine decorated TMU-4 with the formula [Zn(OBA)(BPDB)]·2DMF, azine-methyl functionalized TMU-5 with the formula [Zn(OBA)(BPDH)]·1.

Ultrasonic-Assisted Linker Exchange (USALE): A Novel Post-Synthesis Method for Controlling the Functionality, Porosity, and Morphology of MOFs.

The introduction of organic ligands into metal-organic frameworks (MOFs) with a specific topology and that cannot be attained by direct synthesis is a big challenge. To meet this challenge, different ligand exchange/incorporation methods have been employed. Here, a new method, called ultrasonic-assisted linker exchange (USALE), has been developed to overcome the above-mentioned problems.

High Capacity Oil Denitrogenation over Azine- and Tetrazine-Decorated Metal-Organic Frameworks: Critical Roles of Hydrogen Bonding.

In this work, we demonstrate that rational decoration of pore walls of the metal-organic frameworks (MOFs) with azine and dihydro-tetrazine functions is a very practical strategy for high capacity removal of both neutral and basic nitrogen-containing compounds (NCCs) from model oil. Its performance is even much better than the MOFs with high surface area, open metal sites, and different functional groups such as amine, hydroxyl, carboxy, and sulfonate. For this aim, a number of isostructure functional MOFs (FMOFs) have been synthesized.

Host-Guest Interaction Optimization through Cavity Functionalization for Ultra-Fast and Efficient Water Purification by a Metal-Organic Framework.

To achieve optimized host-guest interactions, a "cavity functionalization" approach has been applied using two isostructure MOFs, [Zn(OBA)(BPDB)] ·2DMF (TMU-4) and [Zn(OBA)(HDPT)] ·DMF (TMU-34), where HOBA = 4,4'-oxybis(benzoic acid), BPDB = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, and HDPT = 3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine. TMU-4 and TMU-34 are functionalized with azine and dihydro-tetrazine groups, respectively. Both of these functions can act as Lewis basic sites, but only the dihydro-tetrazine function inside the cavities of TMU-34 can act as a hydrogen bond donor site.

Morphology-dependent sensing performance of dihydro-tetrazine functionalized MOF toward Al(III).

A pillared MOF, [Zn(OBA)(HDPT)].DMF (TMU-34), based on dihydro tetrazine functionalized pillar spacer (HDPT=3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine) and V-shape dicarboxylate linker (HOBA=4,4'-oxybis(benzoic acid)) was synthesized by reflux and ultrasonic methods. The effects of sonication time, initial concentration of reagents and sonication power on size and morphology have been optimized.

Double Solvent Sensing Method for Improving Sensitivity and Accuracy of Hg(II) Detection Based on Different Signal Transduction of a Tetrazine-Functionalized Pillared Metal-Organic Framework.

To design a robust, π-conjugated, low-cost, and easy to synthesize metal-organic framework (MOF) for cation sensing by the photoluminescence (PL) method, 4,4'-oxybis(benzoic acid) (HOBA) has been used in combination with 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine (DPT) as a tetrazine-functionalized spacer to construct [Zn(OBA)(DPT)]·DMF (TMU-34(-2H)). The tetrazine motif is a π-conjugated, water-soluble/stable fluorophore with relatively weak σ-donating Lewis basic sites. These characteristics of tetrazine make TMU-34(-2H) a good candidate for cation sensing.

Stimuli-Responsive Metal-Organic Framework (MOF) with Chemo-Switchable Properties for Colorimetric Detection of CHCl.

The ligands 3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine (H DPT), as a pillar spacer, and 4,4'-oxybis(benzoic acid) (H OBA), as a dicarboxylate linker, have been used to develop a dihydrotetrazine-functionalized pillared metal-organic framework (MOF), [Zn(OBA)(H DPT) ]⋅DMF (TMU-34), as a functionally convertible stimuli-responsive MOF-based sensor. Sonochemically synthesized TMU-34 powder has been employed in the sensing of volatile organic compounds (VOCs). The results show that TMU-34 can act as a solid-state, naked-eye visual chemosensor for the detection of chloroform in the liquid and gas phases.

Ultrasonic assisted synthesis of a tetrazine functionalized MOF and its application in colorimetric detection of phenylhydrazine.

TMU-34(-2H), [Zn(OBA)(DPT)].DMF, has been sonochemically synthesized by applying HOBA, (4,4'-oxybis(benzoic acid)), as the dicarboxylate linker, and DPT, (3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine), as pillar spacer. Sonication time, concentration of initial reagents, sonication power and molar ratio of pyridine as modulator has been optimized to synthesize nano powder of TMU-34(-2H) including uniform plate morphology.

Improvement of Methane-Framework Interaction by Controlling Pore Size and Functionality of Pillared MOFs.

The rational design of functionalized porous metal-organic frameworks (MOFs) for gas adsorption applications has been applied using three spacer ligands HDPT (3,6-di(pyridin-4-yl)-1,4-dihydro-1,2,4,5-tetrazine), DPT (3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine), and BPDH (2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene) to synthesize TMU-34, [Zn(OBA)(HDPT)]·DMF, TMU-34(-2H), [Zn(OBA)(DPT)]·DMF, and TMU-5, [Zn(OBA)(BPDH)]·1.5DMF, respectively. By controlling the pore size and chemical functionality of these three MOFs, we can improve the interactions between CO and especially CH with the frameworks.