Metal–organic frameworks (MOFs) based on group 3 and 4 metals are considered as the most promising MOFs for varying practical applications including water adsorption, carbon conversion, and ...biomedical applications. The relatively strong coordination bonds and versatile coordination modes within these MOFs endow the framework with high chemical stability, diverse structures and topologies, and interesting properties and functions. Herein, the significant progress made on this series of MOFs since 2018 is summarized and an update on the current status and future trends on the structural design of robust MOFs with high connectivity is provided. Cluster chemistry involving Y, lanthanides (Ln, from La to Lu), actinides (An, from Ac to Lr), Ti, and Zr is initially introduced. This is followed by a review of recently developed MOFs based on group 3 and 4 metals with their structures discussed based on the types of inorganic or organic building blocks. The novel properties and arising applications of these MOFs in catalysis, adsorption and separation, delivery, and sensing are highlighted. Overall, this review is expected to provide a timely summary on MOFs based on group 3 and 4 metals, which shall guide the future discovery and development of stable and functional MOFs for practical applications.
Metal–organic frameworks (MOFs) based on group 3 and 4 metals with high chemical stability, structural diversity, and various interesting properties are reviewed. Cluster and framework chemistry of group 3 and 4 metals are expected to provide a timely summary on MOF development, which shall guide the discovery and development of stable and functional MOFs for practical applications.
Polyoxometalate (POM)-based metal-organic framework (MOF) materials contain POM units and generally generate MOF materials with open networks. POM-based MOF materials, which utilize the advantages of ...both POMs and MOFs, have received increasing attention, and much effort has been devoted to their preparation and relevant applications over the past few decades. They have good prospects in catalysis owing to the electronic and physical properties of POMs that are tunable by varying constituent elements. In this review, we present recent developments in porous POM-based MOF materials, including their classification, synthesis strategies, and applications, especially in the field of catalysis.
POM-based MOF materials, which combine the advantages of both POMs and MOFs, have received increasing attention. In this review, we present the recent developments in porous POM-based MOF materials for the first time, including their classification, synthesis strategies and applications, especially in the field of catalysis.
The incorporation of large π-conjugated ligands into metal–organic frameworks (MOFs) can introduce intriguing photophysical and electrochemical properties into the framework. However, these effects ...are often hindered by the strong π–π interaction and the low solubility of the arylated ligands. Herein, we report the synthesis of a porous zirconium-based MOF, Zr6(μ3-O)4(μ3-OH)4(OH)6(H2O)6(HCHC) (PCN-136, HCHC = hexakis(4-carboxyphenyl)hexabenzocoronene), which is composed of a hexacarboxylate linker with a π-conjugated hexabenzocoronene moiety. Direct assembly of the Zr4+ metal centers and the HCHC ligands was unsuccessful due to the low solubility and the unfavorable conformation of the arylated HCHC ligand. Therefore, PCN-136 was obtained from aromatization-driven postsynthetic annulation of the hexaphenylbenzene fragment in a preformed framework (pbz-MOF-1) to avoid π–π stacking. This postsynthetic modification was done through a single-crystal-to-single-crystal transformation and was clearly observable utilizing single -crystal X-ray crystallography. The formation of large π-conjugated systems on the organic linker dramatically enhanced the photoresponsive properties of PCN-136. With isolated hexabenzocoronene moieties as photosensitizers and Zr–oxo clusters as catalytic sites, PCN-136 was employed as an inherent photocatalytic system for CO2 reduction under visible-light irradiation, which showed increased activity compared with pbz-MOF-1.
Two novel polyoxometalate (POM)-based metal–organic frameworks (MOFs), TBA3ε-PMoV 8MoVI 4O36(OH)4Zn4BTB4/3·xGuest (NENU-500, BTB = benzene tribenzoate, TBA+ = tetrabutylammonium ion) and TBA3ε-PMoV ...8MoVI 4O37(OH)3Zn4BPT (NENU-501, BPT = 1,1′-biphenyl-3,4′,5-tricarboxylate), were isolated. In these compounds, the POM fragments serving as nodes were directly connected with organic ligands giving rise to three-dimensional (3D) open frameworks. The two anionic frameworks were balanced by TBA+ ions residing inside the open channels. They exhibit not only good stability in air but also tolerance to acidic and basic media. Furthermore, they were employed as electrocatalysts for the hydrogen evolution reaction (HER) owing to the combination of the redox activity of a POM unit and the porosity of a MOF. Meanwhile, the HER activities of ε(trim) 4/3 , NENU-5, and HKUST-1 were also studied for comparison. Remarkably, as a 3D hydrogen-evolving cathode operating in acidic electrolytes, NENU-500 exhibits the highest activity among all MOF materials. It shows an onset overpotential of 180 mV and a Tafel slope of 96 mV·dec–1, and the catalytic current density can approach 10 mA·cm–2 at an overpotential of 237 mV. Moreover, NENU-500 and NENU-501 maintain their electrocatalytic activities after 2000 cycles.
Reticular chemistry has been an important guiding principle for the design of metal–organic frameworks (MOFs). This approach utilizes discrete building units (molecules and clusters) that are ...connected through strong bonds into extended networks assisted by topological considerations. Although the simple design principle of connecting points and lines has proved successful, new design strategies are still needed to further explore the structures and functions of MOFs. Herein, we report the design and synthesis of two mixed-ligand MOFs, (CH3)2NH24Zn4O4Zn(TCPP)5BTB8/3 (PCN-137) and Zr6(μ3-O)4(μ3-OH)4TCPPTBTB8/3 (PCN-138) (BTB = 1,3,5-benzene(tris)benzoate, TBTB = 4,4′,4″-(2,4,6-trimethylbenzene-1,3,5-triyl)tribenzoate, and TCPP = tetrakis(4-carboxyphenyl)porphyrin) by the stacking of face-sharing Archimedean solids. In these two MOFs, high-symmetrical metal clusters serve as vertices, and tritopic or tetratopic carboxylate ligands function as triangular and square faces, leading to the formation of two kinds of Archimedean solids (rhombicuboctahedron and cuboctahedron). Furthermore, the ordered accumulation of Archimedean solids successfully gives rise to 3D structures through face-sharing, highlighting the polyhedron-based approach for the design and preparation of MOFs. In addition, PCN-138 was utilized as a heterogeneous catalyst toward CO2 photoreduction under visible-light irradiation. This structure shows high photocatalytic activity, which can be attributed to the coexistence of photosensitizing porphyrin fragments and Zr-oxo centers within the PCN-138 scaffold.
A 2D, extremely stable, metal–organic framework (MOF), NENU‐503, was successfully constructed. It displays highly selective and recyclable properties in detection of nitroaromatic explosives as a ...fluorescent sensor. This is the first MOF that can distinguish between nitroaromatic molecules with different numbers of NO2 groups.
Detection of explosives: A 2D, extremely stable, metal–organic framework (MOF) was successfully constructed. It displays highly selective and recyclable properties for detection of nitroaromatic explosives as a fluorescent sensor (see figure). This is the first MOF that can distinguish between nitroaromatic molecules with different numbers of NO2 groups.
Chiral POM-based materials are particularly attractive due to the combination of the advantage of POMs with the importance of chirality. In this review, we summarize the developments of chiral ...POM-based materials, including their synthetic strategies, the calculations on the origin of chirality and the relevant applications. Display omitted
► We review the synthesis strategies and recent results of chiral polyoxometalates (POMs). ► Theoretical calculations on the origin of chirality within chiral POMs were discussed. ► The applications of chiral POMs in asymmetric catalysis, molecular recognition and NLO materials were summarized. ► The challenges of preparation and applications of chiral POMs were discussed.
Owing to the potential applications in catalysis, analytical chemistry, ion exchange, magnetism, biological chemistry and medicine, tremendous effort has been dedicated to exploring polyoxometalate (POM) chemistry. Chiral POM-based materials are particularly attractive due to the combination of the advantage of POMs with the importance of chirality. Nearly 100 chiral POM-based compounds were reported, which were mainly used as asymmetric catalysts, molecular recognition and nonlinear optical materials. In addition, the chirality within POM systems has attracted the attention of theoretical chemists and research was carried out to explore the origin of chirality by density functional theoretical methods. In this review, we summarize the developments of chiral POM-based materials, including their synthetic strategies, calculations on the origin of chirality and the relevant applications.
Herein, a novel anionic framework with primitive centered cubic (pcu) topology, (CH3)2NH24(Zn4dttz6)Zn3⋅15 DMF⋅4.5 H2O, (IFMC‐2; H3dttz=4,5‐di(1H‐tetrazol‐5‐yl)‐2H‐1,2,3‐triazole) was solvothermally ...isolated. A new example of a tetranuclear zinc cluster {Zn4dttz6} served as a secondary building unit in IFMC‐2. Furthermore, the metal cluster was connected by ZnII ions to give rise to a 3D open microporous structure. The lanthanide(III)‐loaded metal–organic framework (MOF) materials Ln3+@IFMC‐2, were successfully prepared by using ion‐exchange experiments owing to the anionic framework of IFMC‐2. Moreover, the emission spectra of the as‐prepared Ln3+@IFMC‐2 were investigated, and the results suggested that IFMC‐2 could be utilized as a potential luminescent probe toward different Ln3+ ions. Additionally, the absorption ability of IFMC‐2 toward ionic dyes was also performed. Cationic dyes can be absorbed, but not neutral and anionic dyes, thus indicating that IFMC‐2 exhibits selective absorption toward cationic dyes. Furthermore, the cationic dyes can be gradually released in the presence of NaCl.
A tetranuclear metal cluster with primitive centered cubic (pcu) topology, IFMC‐2, was synthesized as a new anionic metal–organic framework (MOF). The Ln3+‐loaded MOF materials were successfully prepared by ion exchange, and the emission spectra indicated that IFMC‐2 is suitable for the sensitization of Tb3+ and Dy3+ ions rather than as a Eu3+ and Sm3+ emitter (see picture). Additionally, IFMC‐2 exhibits selective absorption toward cationic dyes, which can be gradually released in the presence of NaCl.
As glutamate dehydrogenases (GDHs) of microorganisms usually have higher affinity for NH4+ than do those of higher plants, it is expected that ectopic expression of these GDHs can improve nitrogen ...assimilation in higher plants. Here, a novel NADP(H)-GDH gene (TrGDH) was isolated from the fungus Trichurus and introduced into rice (Oryza sativa L.). Investigation of kinetic properties in vitro showed that, compared with the rice GDH (OsGDH4), TrGDH exhibited higher affinity for NH4+ (Km = 1.48 ± 0.11 mM). Measurements of the NH4+ assimilation rate demonstrated that the NADP(H)-GDH activities of TrGDH transgenic lines were significantly higher than those of the controls. Hydroponic experiments revealed that the fresh weight, dry weight and nitrogen content significantly increased in the TrGDH transgenic lines. Field trials further demonstrated that the number of effective panicles, 1,000-grain weight and grain weight per plant of the transgenic lines were significantly higher than those of the controls, especially under low-nitrogen levels. Moreover, glutelin and prolamine were found to be markedly increased in seeds from the transgenic rice plants. These results sufficiently confirm that overexpression of TrGDH in rice can improve the growth status and grain weight per plant by enhancing nitrogen assimilation. Thus, TrGDH is a promising candidate gene for maintaining yields in crop plants via genetic engineering.
Two novel polyoxometalate (POM)‐based coordination polymers, namely, Co(bpz)(Hbpz)Co(SO4)0.5(H2O)2(bpz)4 PMoVI8MoV4VIV4O42⋅13 H2O (NENU‐530) and Ni2(bpz)(Hbpz)3(H2O)2PMoVI8MoV4VIV4O44⋅8 H2O ...(NENU‐531) (H2bpz=3,3′,5,5′‐tetramethyl‐4,4′‐bipyrazole), were isolated by hydrothermal methods, which represented 3D networks constructed by POM units, the protonated ligand and sulfate group. In contrast with most POM‐based coordination polymers, these two compounds exhibit exceptional excellent chemical and thermal stability. More importantly, NENU‐530 shows a high proton conductivity of 1.5×10−3 S cm−1 at 75 °C and 98 % RH, which is one order of magnitude higher than that of NENU‐531. Furthermore, structural analysis and functional measurement successfully demonstrated that the introduction of sulfate group is favorable for proton conductivity. Herein, the syntheses, crystal structures, proton conductivity, and the relationship between structure and property are presented.
Taking charge: Two novel polyoxometalate (POM)‐based coordination polymers were isolated by hydrothermal reactions, which present 3D networks constructed by POMs, the protonated ligand and sulfate group. NENU‐530 shows a high proton conductivity of 1.5×10−3 S cm−1 at 75 °C and 98 % relative humidity, which is one order of magnitude higher than that of NENU‐531.
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