Defect-enabling zirconium-based metal-organic frameworks for energy and environmental remediation applications.

This comprehensive review explores the diverse applications of defective zirconium-based metal-organic frameworks (Zr-MOFs) in energy and environmental remediation. Zr-MOFs have gained significant attention due to their unique properties, and deliberate introduction of defects further enhances their functionality. The review encompasses several areas where defective Zr-MOFs exhibit promise, including environmental remediation, detoxification of chemical warfare agents, photocatalytic energy conversions, and electrochemical applications. Defects play a pivotal role by creating open sites within the framework, facilitating effective adsorption and remediation of pollutants. They also contribute to the catalytic activity of Zr-MOFs, enabling efficient energy conversion processes such as hydrogen production and CO2 reduction. The review underscores the importance of defect manipulation, including control over their distribution and type, to optimize the performance of Zr-MOFs. Through tailored defect engineering and precise selection of functional groups, researchers can enhance the selectivity and efficiency of Zr-MOFs for specific applications. Additionally, pore size manipulation influences the adsorption capacity and transport properties of Zr-MOFs, further expanding their potential in environmental remediation and energy conversion. Defective Zr-MOFs exhibit remarkable stability and synthetic versatility, making them suitable for diverse environmental conditions and allowing for the introduction of missing linkers, cluster defects, or post-synthetic modifications to precisely tailor their properties. Overall, this review highlights the promising prospects of defective Zr-MOFs in addressing energy and environmental challenges, positioning them as versatile tools for sustainable solutions and paving the way for advancements in various sectors toward a cleaner and more sustainable future.

Correction: Defect-enabling zirconium-based metal-organic frameworks for energy and environmental remediation applications.

Correction for 'Defect-enabling zirconium-based metal-organic frameworks for energy and environmental remediation applications' by Saba Daliran et al., Chem. Soc. Rev., 2024, https://doi.org/10.1039/d3cs01057k.

Application of a magnetically separable Zr-MOF for fast extraction of palladium before its spectrophotometric detection.

In this research, a novel magnetic zirconium-based metal-organic framework (Fe3O4@SiO2@MIP-202, MMOF), was fabricated, fully characterized, and applied for the batch-mode solid phase extraction of trace amounts of Pd2+ ions from water and wastewater samples before its spectrophotometric detection. Pd2+ ions were desorbed from MMOF by nitric acid and were complexed by treating with KI solution to have a maximum absorbance at 410 nm. The synthesized MMOF composite showed a very large surface area (65 m2.g- 1), good magnetization (1.7 emu.g- 1) and a large pore volume (0.059 cm3.g- 1) with adsorption capacity of 194.5 mg of Pd2+ ions/g of the adsorbent. This nanosorbent boasts chemo-mechanical stability, high adsorption capacity due to its vast active sites, and facile recovery facilitated by its magnetic properties. Parameters affecting the extraction efficiency of the method were optimized as pH of the sample 7.4, volume of the sample 25 mL, 15 mg adsorbent, 1 mL of 0.1 M HNO3 eluent, with 10 and 15 min as the extraction and desorption times, respectively. The calibration curve was found to be linear across the 10.0-1500.0 µg.L- 1 range with a limit of detection of 1.05 µg.L- 1. The obtained extraction efficiency and enrichment were 98% and 245, respectively. The total analysis time was less than 30 min. This MMOF has never been used for the extraction of Pd2+ ions before.

Sulfur-functionalized porphyrin-based covalent organic framework as a metal-free dual-functional catalyst for photodegradation of organophosphorus pesticides under visible-LED-light.

Parathion and diazinon are two significant organophosphorus pesticides broadly used in agriculture. However, these compounds are toxic and can enter into the environment and atmosphere via various processes. Herein, we synthesized and post-functionalized a porphyrinic covalent organic framework (COF), COF-366, with elemental sulfur under solvent-free conditions to give polysulfide-functionalized COF-366, namely PS@COF. The resulting material consisting of porphyrin sensitizer and sulfur nucleophilic sites was used as a dual-functional heterogeneous catalyst for the degradation of these organic compounds using visible-LED-light. Accordingly, the effects of several pertinent parameters such as pH (3-9), the catalyst dosage (5-30 mg), time (up to 80 min), and substrate concentration (10-50 mg L-1) were studied in detail and optimized. The post-modified COF showed excellent photocatalytic activity (>97%) in the detoxification of diazinon and parathion for 60 min at pH 5.5. Kinetic studies indicated a fast degradation rate with pseudo-second order model for 20 mg L-1 of diazinon and parathion. The total organic carbon detection and gas chromatography-mass spectrometry (GC-MS) confirmed the organic intermediates and byproducts formed during the process. PS@COF displayed good recyclability and high reusable efficiency for six cycles without a noteworthy lose in its catalytic activity, owing to its robust structure.

A Porphyrin-Based Covalent Organic Framework as Metal-Free Visible-LED-Light Photocatalyst for One-Pot Tandem Benzyl Alcohol Oxidation/Knoevenagel Condensation.

A porphyrin-based covalent organic framework (COF), namely Porph-UOZ-COF (UOZ stands for the University of Zabol), has been designed and prepared via the condensation reaction of 5,10,15,20-tetrakis-(3,4-dihydroxyphenyl)porphyrin (DHPP) with 1,4-benzenediboronic acid (DBBA), under the solvothermal condition. The solid was characterized by spectroscopic, microscopic, and powder X-ray diffraction techniques. The resultant multifunctional COF revealed an outstanding performance in catalyzing a one-pot tandem selective benzylic C-H photooxygenation/Knoevenagel condensation reaction in the absence of additives or metals under visible-LED-light irradiation. Notably, the catalytic activity of the COF was superior to individual organic counterparts and the COF was both stable and reusable for four consecutive runs. The present approach illustrates the potential of COFs as promising metal-free (photo) catalysts for the development of tandem reactions.

Recent Advances in the Use of Covalent Organic Frameworks as Heterogenous Photocatalysts in Organic Synthesis.

Organic photochemistry is intensely developed in the 1980s, in which the nature of excited electronic states and the energy and electron transfer processes are thoroughly studied and finally well-understood. This knowledge from molecular organic photochemistry can be transferred to the design of covalent organic frameworks (COFs) as active visible-light photocatalysts. COFs constitute a new class of crystalline porous materials with substantial application potentials. Featured with outstanding structural tunability, large porosity, high surface area, excellent stability, and unique photoelectronic properties, COFs are studied as potential candidates in various research areas (e.g., photocatalysis). This review aims to provide the state-of-the-art insights into the design of COF photocatalysts (pristine, functionalized, and hybrid COFs) for organic transformations. The catalytic reaction mechanism of COF-based photocatalysts and the influence of dimensionality and crystallinity on heterogenous photocatalysis performance are also discussed, followed by perspectives and prospects on the main challenges and opportunities in future research of COFs and COF-based photocatalysts.

Correction: Metal-organic framework (MOF)-, covalent-organic framework (COF)-, and porous-organic polymers (POP)-catalyzed selective C-H bond activation and functionalization reactions.

Correction for 'Metal-organic framework (MOF)-, covalent-organic framework (COF)-, and porous-organic polymers (POP)-catalyzed selective C-H bond activation and functionalization reactions' by Saba Daliran et al., Chem. Soc. Rev., 2022, https://doi.org/10.1039/d1cs00976a.

Metal-organic framework (MOF)-, covalent-organic framework (COF)-, and porous-organic polymers (POP)-catalyzed selective C-H bond activation and functionalization reactions.

Although C-H functionalization is one of the simplest reactions, it requires the use of highly active and selective catalysts. Recently, C-H-active transformations using porous materials such as crystalline metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) as well as amorphous porous-organic polymers (POPs) as new emerging heterogeneous catalysts have attracted significant attention due to their promising activity and potential material tunability. These porous solids offer exceptional structural uniformity, facile tunability and permanent porosity. In addition, tuning the catalytic selectivity of these porous materials can be achieved through engineering their site microenvironments, such as metal node substitution, linker changes, node/linker functionalization, and pore modification. The present review provides an overview of the current state of the art on MOFs, COFs and POPs as advanced catalysts for various C-H bond activation reactions, providing details about their chemo-, regio-, and stereo-selectivity control, comparing their performance with that of other catalysts, triggering additional research by showing the present limitations and challenges in this area, and providing a perspective for future developments.

CsCu2I3 Nanoparticles Incorporated within a Mesoporous Metal-Organic Porphyrin Framework as a Catalyst for One-Pot Click Cycloaddition and Oxidation/Knoevenagel Tandem Reaction.

Metal-organic frameworks (MOFs) and metal halide perovskites are currently under much investigation due to their unique properties and applications. Herein, an innovative strategy has been developed combining an iron-porphyrin MOF, PCN-222(Fe), and an in situ-grown CsCu2I3 nontoxic lead-free halide perovskite based on an earth-abundant metal that becomes incorporated within the MOF channels [CsCu2I3@PCN-222(Fe)]. Encapsulation was designed to decrease and control the particle size and increase the stability of CsCu2I3. The hybrid materials were characterized by various techniques including FE-SEM, elemental mapping and line scanning EDX, TEM, PXRD, UV-Vis DRS, BET surface area, XPS, and photoemission measurements. Hybrid CsCu2I3@PCN-222(Fe) materials were examined as heterogeneous multifunctional (photo)catalysts for copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) and one-pot selective photo-oxidation/Knoevenagel condensation cascade reaction. Interestingly, CsCu2I3@PCN-222(Fe) outperforms not only its individual components CsCu2I3 and PCN-222(Fe) but also other reported (photo)catalysts for these transformations. This is attributed to cooperation and synergistic effects of the PCN-222(Fe) host and CsCu2I3 nanocrystals. To understand the catalytic and photocatalytic mechanisms, control and inhibition experiments, electron paramagnetic resonance (EPR) measurements, and time-resolved phosphorescence were performed, revealing the main role of active species of Cu(I) in the click reaction and the superoxide ion (O2•-) and singlet oxygen (1O2) in the photocatalytic reaction.

Poly(lauryl methacrylate)-Grafted Amino-Functionalized Zirconium-Terephthalate Metal-Organic Framework: Efficient Adsorbent for Extraction of Polycyclic Aromatic Hydrocarbons from Water Samples.

In this study, a novel porous hybrid material, poly(lauryl methacrylate) polymer-grafted UiO-66-NH2 (UiO = University of Oslo), was synthesized for efficient extraction of polycyclic aromatic hydrocarbons (PAHs) from aqueous samples. The polymer end-tethered covalently to the MOF's surface was synthesized by surface-initiated atom transfer radical polymerization, revealing a distinct type of morphology. The adsorbent was characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, powder X-ray diffraction, N2 adsorption-desorption analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The analyses were carried out by gas chromatography-mass spectrometry. Parameters including the type and volume of the eluent, the amount of the adsorbent, and adsorption and desorption times were investigated and optimized. Under optimal conditions, the limit of detection, intraday precision, and interday precision were in the range of 3-8 ng L-1, 1.4-3.1, and 4.1-6.5%, respectively. The procedure was used for analysis of PAHs from natural water samples.

A Pyridyltriazol Functionalized Zirconium Metal-Organic Framework for Selective and Highly Efficient Adsorption of Palladium.

This work reports the synthesis of pyridyltriazol-functionalized UiO-66 (UiO stands for University of Oslo), namely, UiO-66-Pyta, from UiO-66-NH2 through three postsynthetic modification (PSM) steps. The good performance of the material derives from the observation that partial formylation (∼21% of -NHCHO groups) of H2BDC-NH2 by DMF, as persistent impurity, takes place during the synthesis of the UiO-66-NH2. Thus, to enhance material performance, first, the as-synthesized UiO-66-NH2 was deformylated to give pure UiO-66-NH2. Subsequently, the pure UiO-66-NH2 was converted to UiO-66-N3 with a nearly complete conversion (∼95%). Finally, the azide-alkyne[3+2]-cycloaddition reaction of 2-ethynylpyridine with the UiO-66-N3 gave the UiO-66-Pyta. The porous MOF was then applied for the solid-phase extraction of palladium ions from an aqueous medium. Affecting parameters on extraction efficiency of Pd(II) ions were also investigated and optimized. Interestingly, UiO-66-Pyta exhibited selective and superior adsorption capacity for Pd(II) with a maximum sorption capacity of 294.1 mg g-1 at acidic pH (4.5). The limit of detection (LOD) was found to be 1.9 µg L-1. The estimated intra- and interday precisions are 3.6 and 1.7%, respectively. Moreover, the adsorbent was regenerated and reused for five cycles without any significant change in the capacity and repeatability. The adsorption mechanism was described based on various techniques such as FT-IR, PXRD, SEM/EDS, ICP-AES, and XPS analyses as well as density functional theory (DFT) calculations. Notably, as a case study, the obtained UiO-66-Pyta after palladium adsorption, UiO-66-Pyta-Pd, was used as an efficient catalyst for the Suzuki-Miyaura cross-coupling reaction.

PCN-222 metal-organic framework: a selective and highly efficient sorbent for the extraction of aspartame from gum, juice, and diet soft drink before its spectrophotometric determination.

In this paper, we describe synthesis and application of an iron porphyrinc metal-organic framework PCN-222(Fe) for solid phase extraction of aspartame, an artificial non-saccharine sweetener, from gum, juice and diet soft drink samples prior to its determination by spectrophotometry. The mesoporous MOF was synthesized solvo-thermally and characterized by Fourier transform-infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller techniques. To obtain the best extraction efficiency of aspartame, significant affecting parameters such as pH of sample solution, amount of the sorbent, type and volume of eluting solvent, and adsorption and desorption times were investigated and optimized. Under optimum conditions, the calibration graph for aspartame was linear in the range of 0.1 to 100.0 mg.L-1 and relative standard deviation of aspartame was 1.7% (n = 7). Limit of detection of method calculated as 0.019 mg.L-1 and the enrichment factor of 350 folds was obtained. Adsorption capacity of synthesized sorbent was found to be 356 mg.g-1. Hierarchical porosity, the eight terminal-OH groups of the Zr6 node, and hydrogen bonding possibly play vital role for selective adsorption of aspartame. The optimized method was successfully applied to the determination of aspartame in real samples with reasonable recoveries (> 98%).

Co-Fe-layered double hydroxide decorated amino-functionalized zirconium terephthalate metal-organic framework for removal of organic dyes from water samples.

In this study, a new efficient adsorbent of Co-Fe-layered double hydroxides@metal-organic framework (Co-Fe-LDH@UiO-66-NH2) was synthesized and used for extraction of methylene blue (MB) and methylene red (MR) from water samples prior to their determination by UV-Vis spectrophotometer. The adsorbent was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX), X-ray Diffraction (XRD), and Brunauer-Emmett-Teller (BET) analyses. The impact of various parameters such as pH of the aqueous phase, extraction time, amount of adsorbent, type and volume of eluent solvent, desorption time, and sample volume were studied. The maximum extraction recovery was obtained at an optimized pH 8.0 and extraction time 10.0 min. The adsorption process was fitted by the Langmuir model with a maximum adsorption capacity of 555.62 mg/g and 588.2 mg/g, respectively, for MB and MR. Under optimum conditions, the limit of detection (LOD) for MB was 0.7 µgL-1 and 0.9 µgL-1 for MR. Furthermore, the Co-Fe-LDH@UiO-66-NH2 composite showed high efficiency for the removal of the analytes from environmental water samples.

New porphyrins: synthesis, characterization, and computational studies.

New trans-A2B2-porphyrins substituted at phenyl positions were synthesized from 4-methylphthalic acid as a starting material through sequential multistep reactions. These macrocycles were characterized by 1H NMR, 13C NMR, 19F NMR, 1H-1H COSY NMR, and MALDI-TOF mass spectrometry. Computational studies were performed on the porphyrins to investigate various factors such as structural features, electronic energy, energy gaps, and aromaticity. Energy band gap values of these compounds especially N-hydroxyphthalimide-functionalized porphyrins were small that makes them as good candidates for solar cell systems and photocatalysis. Relationships between electronic energies and aromaticity of the compounds were then investigated. The data indicated that the aromaticity features at the center of two series of these compounds (fluorinated and non-fluorinated porphyrins) were in the opposite manner.

Brønsted-Lewis dual acid sites in a chromium-based metal-organic framework for cooperative catalysis: Highly efficient synthesis of quinazolin-(4H)-1-one derivatives.

A novel MIL-101(Cr) (MIL, Matérial Institut Lavoisier) supported propyl carboxylic acid, denoted here as MIL-101(Cr)-NH-CO-Pr-COOH, has been fabricated by post-synthetic modifications of nitro-functionalized MIL-101(Cr), MIL-101(Cr)-NO2. The resulting MOF was successfully characterized by using FT-IR, XRD, N2 adsorption-desorption, 1H NMR, SEM, ICP-OES, elemental analysis and TGA. Then, the prepared solid was used as an extremely highly effective multifunctional catalyst for the one-pot three-component synthesis of quinazolin-4(1H)-one derivatives as biologically active nitrogen heterocyclic compounds under solvent-free conditions. The important features of this methodology are good to excellent yields of products, the use of very small amounts of catalyst, short reaction time, non-requirement of organic solvents, and environmental benign and mild reaction conditions. Furthermore, turnover frequency was found to be in the range 3.5-50 h-1 under neat conditions, which is comparable to the reported previously for this reaction. Significantly, compared with the pristine MOF and the related homogenous catalysts, the MIL-10 1(Cr)-NHCO-Pr-COOH exhibited superior catalytic activity which can be attributed to the synergistic effect between isolated Lewis acidic Cr(III) nodes and Brønsted acidic free COOH groups in addition to the cooperative interplay of the Brønsted acid and the amine sites within the framework. More remarkably, MOF was stable and reusable up to three times without any changes in its activity and structure.

A hybrid material composed of an amino-functionalized zirconium-based metal-organic framework and a urea-based porous organic polymer as an efficient sorbent for extraction of uranium(VI).

An amino-functionalized zirconium metal-organic framework was composed with a 3D urea-based porous organic polymer to give a hybrid material termed UiO-66-NH2/urea-POP. The material was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller surface area measurements. It is shown to be a viable sorbent for solid-phase extraction of uranium from water samples. Parameters such as the pH value of the sample, amount of adsorbent, type and volume of eluent, adsorption and desorption time, and sample volume were optimized. Uranyl ion was quantified by using UV-vis spectrophotometry by using 1-(2-pyridyl-azo)-2-naphthol as the indicator. Figures of merits include (a) a maximum sorption capacity of 278 mg g-1; (b) a detection limit of 0.6 µg L-1; and (c) intra-day and inter-day precisions (for n = 5 at a concentration of 100 µg L-1) of 4.8 and 1.9%, respectively. The sorbent can be recycled, and no significant change was observed in the capacity and repeatability of the sorbent after seven extractions. The high surface area, metal-binding sites, and stability of the sorbent makes it a most viable tool for efficient and fast extraction and removal of uranium. Graphical abstract Schematic of a new porous hybrid solid, referred to as UiO-66-NH2/urea-POP. It combines a zirconium-based metal-organic framework and a urea-based porous organic polymer. It is shown to be a highly efficient sorbent for solid-phase extraction of uranium(VI) prior to its spectrophotometric determination.

Cu(II)-Schiff base covalently anchored to MIL-125(Ti)-NH2 as heterogeneous catalyst for oxidation reactions.

MIL-125(Ti)-NH2 has been modified by reaction of salicylaldehyde with the terephthalate amino groups to form a salicylideneimine that act as ligand of Cu2+. The success of the postsynthetic modification was assessed by FTIR spectroscopy of the MIL-125(Ti)-NH2-Sal-Cu and by analysis by 1H NMR spectroscopy of the organic linkers upon dissolution of MIL-125(Ti)-NH2-Sal-Cu. In comparison with parent MIL-125(Ti)-NH2 and MIL-125(Ti)-NH2-Sal, that exhibit a poor activity, the presence of the Cu-Schiff base complex in MIL-125(Ti)-NH2-Sal-Cu catalyst for the oxidation of 1-phenylethanol by tert-butylhydroperoxyde (TBHP, 3 eq.) increases notably the catalytic activity. Hot filtration test and reusability experiments confirm that the process is heterogeneous and that MIL-125(Ti)-NH2-Sal-Cu is stable under the reaction conditions. Quenching studies and EPR spectra using N-tbutylphenylnitrone indicate the generation of tBuOO and tBuO under the reaction conditions. The scope of MIL-125(Ti)-NH2-Sal-Cu as oxidation catalyst by tBuOOH was studied for benzyl alcohol as well as alicyclic and aliphatic alcohols and ethylbenzene.

Determination of carbamazepine in urine and water samples using amino-functionalized metal-organic framework as sorbent.

A stable and porous amino-functionalized zirconium-based metal organic framework (Zr-MOF-NH2) containing missing linker defects was prepared and fully characterized by FTIR, scanning electron microscopy, powder X-ray diffraction, and BET surface area measurement. The Zr-MOF-NH2 was then applied as an adsorbent in pipette-tip solid phase extraction (PT-SPE) of carbamazepine. Important parameters affecting extraction efficiency such as pH, sample volume, type and volume of eluent, amount of adsorbent, and number of aspirating/dispensing cycles for sample solution and eluent solvent were investigated and optimized. The best extraction efficiency was obtained when pH of 100 µL of sample solution was adjusted to 7.5 and 5 mg of the sorbent was used. Eluent solvent was 10 µL methanol. Linear dynamic range was found to be between 0.1 and 50 µg L-1 and limit of detection for 10 measurement of blank solution was 0.05 µg L-1. This extraction method was coupled to HPLC and was successfully employed for the determination of carbamazepine in urine and water samples. The strategy combined the advantages of fast and easy operation of PT-SPE with robustness and large adsorption capacity of Zr-MOF-NH2.

Urea-based porous organic polymer/graphene oxide hybrid as a new sorbent for highly efficient extraction of bovine serum albumin prior to its spectrophotometric determination.

A 3D urea-based porous organic polymer (Urea-POP) was prepared via the reaction of tetrakis(4-aminophenyl)methane and 1,4-Phenylene diisocyanate. The polymer was subsequently reacted with 2D layered nanosheets of graphene oxide (GO) to prepare Urea-POP/GO as a novel and highly efficient sorbent for pre-concentration and extraction of serum albumin samples, prior to spectrophotometric determination. The hybrid material combines advantages of both POP and GO such as hydrophilicity, high dispersion stability, porosity, and having a large number of nitrogen- and oxygen-containing functional groups. Parameters which influence the extraction efficiency such as the amount of the adsorbent, pH of sample solution, ionic strength, adsorption and desorption time were investigated and optimized. For the method, detection limit of 0.068 mg L-1 and determination coefficient (R2) of 0.9991 were obtained. The intra- and inter-day was calculated with five replicates in the same day and seven consecutive days, respectively. Intra-day and inter-day precisions were 1.7% and 5.9%, respectively. The maximum sorption capacity was 357.1 mg g-1, which is higher than the other reported sorbents. The proposed method was demonstrated to be sensitive enough for determination of serum albumin from bio-samples.

Synthesis of UiO-66-OH zirconium metal-organic framework and its application for selective extraction and trace determination of thorium in water samples by spectrophotometry.

In this study, a zirconium-based metal-organic framework (Zr-MOF), named UiO-66-OH, was synthesized by the solvo-thermal method and characterized by Fourier transform-infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). This Zr-MOF was then employed as a sorbent for selective extraction and preconcentration of thorium ions after their complexation with 2­(2,4­dihydroxyphenyl)­3,5,7­trihydroxychromen­4­one (morin) from environmental water samples prior to its spectrophotometrical determination. The experimental parameters affecting extraction, such as pH of sample solution, amount of Zr-MOF, type and volume of eluting solvent, adsorption and desorption time, and concentration of complexing agent were evaluated and optimized. Under the optimized conditions, an enrichment factor of 250 was achieved. The limit of detection was calculated to be 0.35µg·L-1 with a linear range between 10 and 2000µg·L-1of thorium. The maximum sorption capacity of MOF toward thorium was found to be 47.5mg·g-1. The proposed procedure was successfully applied to the analysis of real water samples.