An Exceptionally Stable Metal–Organic Framework Constructed from Chelate-Based Metal–Organic Polyhedra

Bayesian Optimized Crystallization of a Hydroxamate-Functionalized Covalent Organic Framework for Enhanced Uranyl Uptake

To address the synthetic challenge of covalent organic frameworks (COFs), especially those with interfering functional groups, a Bayesian optimization (BO) centered approach is developed and implemented. Specifically, the crystallinity index for a well-known TAPB-PDA COF is improved by ≈80% via a one-round proof-of-concept BO. For a more complicated task toward the preparation of hydroxamate-functionalized TpPa COF, where improvement of both crystallinity and selectivity (against a crystalline byproduct) is needed, an efficient protocol comprising 6 BO iterations (with 5 experiments each) from an initial 64-experiment dataset is successfully developed. The functional COF, namely SUM-99 (SUM = Sichuan University Materials), with enhanced crystallinity, is subsequently demonstrated to be an effective, reversible, and selective sorbent for aquatic uranyl uptake. The importance of improved crystallinity, reflecting the power of BO, is showcased by a 23.7% increase in uranyl adsorption capacity. Therefore, the BO protocol and toolkit is presented for the efficient evolution of COF synthetic conditions, toward higher crystallinity and enhanced performances for downstream applications.

Construction of robust Cu-MOFs from bifunctional pyridine-hydroxamate linkers for photocatalytic CO2 reduction

Robust Cu-MOFs with distinct topologies were prepared from the same bifunctional 4-pyridine-hydroxamate ligand. A favourable collection of porosity, framework stability, electronic structure, and photochemical properties was revealed for the SUM-33 MOF, which was later experimentally verified as an efficient and selective photocatalyst for CO2-to-CO conversion.

Hydroxamate-Based Metal-Organic Frameworks

This mini-review focuses on recent developments in hydroxamate-based metal-organic frameworks (MOFs), which exhibit unique structures and properties distinct from those of carboxylate-based MOFs. Hydroxamates (RCONHO-) form MOFs with novel structural motifs and functionalities. In this review, synthetic strategies, structural characteristics, and functional applications of key examples of hydroxamate-based MOFs are described, providing insights into the influence of the hydroxamate ligand on the MOF properties compared to that of the carboxylate-based analogues.

Understanding water reaction pathways to control the hydrolytic reactivity of a Zn metal-organic framework

Metal-organic frameworks (MOFs) are a class of porous materials that are of topical interest for their utility in water-related applications. Nevertheless, molecular-level insight into water-MOF interactions and MOF hydrolytic reactivity remains understudied. Herein, we report two hydrolytic pathways leading to either structural stability or framework decomposition of a MOF (ZnMOF-1). The two distinct ZnMOF-1 water reaction pathways are linked to the diffusion rate of incorporated guest dimethylformamide (DMF) molecules: slow diffusion of DMF triggers evolution of the initial MOF into a water-stable MOF product exhibiting enhanced water adsorption, while fast exchange of DMF with water leads to decomposition. The starting MOF, three intermediates from the water reaction pathways and the final stable MOF have been characterized. The documentation of two distinct pathways counters the stereotype that water exposure always leads to destruction or degradation of water-sensitive MOFs, and demonstrates that water-stable MOFs with improved adsorption properties can be prepared via controlled solvent-triggered structural rearrangement.

DNA binding studies and in-vitro anticancer studies of novel lanthanide complexes

Pancreatic cancer, is an aggressive type of cancer and the most common malignancy with a poor prognosis regarding metastatic disease (survival < 10 %). The development of Novel chemotherapeutic drugs holds significant prospects for practical applications. Here, this work focuses on the interaction between two lanthanide complexes, Yb-BZA and Er-BZA, with DNA, as well as their anticancer activity against pancreatic cancer. The relationship between complexes and DNA is revealed by fluorescence, absorption spectral titration, cyclic voltammetric (CV) experiments, indicating that the Yb-BZA and Er-BZA interact with FS-DNA by bind groove. Moreover, molecular docking technology was utilized to confirm the binding of Yb-BZA and Er-BZA with 1BNA and 4AV1. The cytotoxic effects of Yb-BZA and Er-BZA on cancer cells BxPC-3 were evaluated, Yb-BZA (IC50 = 6.459 μg/mL) is more effective than oxaliplatin (IC50 = 16.46 μg/mL) evaluated using cytotoxicity assay. Yb-BZA and Er-BZA has the potential to become a chemotherapy drug for pancreatic cancer cells.

Energy transfer-mediated multiphoton synergistic excitation for selective C(sp3)-H functionalization with coordination polymer

Activation and selective oxidation of inert C(sp3)-H bonds remain one of the most challenging tasks in current synthetic chemistry due to the inherent inertness of C(sp3)-H bonds. In this study, inspired by natural monooxygenases, we developed a coordination polymer with naphthalenediimide (NDI)-based ligands and binuclear iron nodes. The mixed-valence FeIIIFeII species and chlorine radicals (Cl•) are generated via ligand-to-metal charge transfer (LMCT) between FeIII and chlorine ions. These Cl• radicals abstract a hydrogen atom from the inert C(sp3)-H bond of alkanes via hydrogen atom transfer (HAT). In addition, NDI converts oxygen to 1O2 via energy transfer (EnT), which then coordinates to FeII, forming an FeIV = O intermediate for the selective oxidation of C(sp3)-H bonds. This synthetic platform, which combines photoinduced EnT, LMCT and HAT, provides a EnT-mediated parallel multiphoton excitation strategy with kinetic synergy effect for selective C(sp3)-H oxidation under mild conditions and a blueprint for designing coordination polymer-based photocatalysts for C(sp3)-H bond oxidation.

A Zr-hydroxamate metal-organic framework with intrinsic chelating sites for postsynthetic Pd metalation and Suzuki-Miyaura catalysis

A highly crystalline and robust Zr-hydroxamate metal-organic framework (MOF) was prepared from a pyrazine-based ligand, featuring abundant N,N' chelating sites. High-degree Pd(II) metalation of the MOF was achieved through straightforward postsynthetic modification, with detailed coordination chemistry elucidated spectroscopically. The Pd-functionalized MOF was then studied as a heterogeneous Suzuki-Miyaura catalyst, through combined experimental/computational methods.

Structural Diversity in Ga/In-Hydroxamate Metal-Organic Materials

Developing metal-organic materials (MOMs) with chemical robustness is a prerequisite to exploring their intriguing properties and applications. As part of a continuing effort to construct robust MOMs featuring chelated building units, here we introduce a "bent" thiophene-2,5-dihydroxamate ligand with multiple intrinsic conformations when it is used as a chelating linkage. This approach should further diversify the coordination chemistry in hydroxamate-based MOM structures without compromising the stability. In combination with Group 13 metals Ga/In to ensure homoleptic metal vertices, we report the successful crystallization of four MOMs with diverse structures and dimensionalities: SUM-81 as a 0D metal-organic polyhedron (MOP), SUM-82 as a 2D MOF with an fes topology, SUM-83 and SUM-84 as distinct 1D coordination polymers with shapes mimic stairs and mesh tubes, respectively. As these structures indeed contain the aforementioned different ligand conformations and combinations thereof, these results expand our understanding of the coordination chemistry of hydroxamates. To demonstrate the potential applicability of hydroxamate-chelated robust MOMs, the permanently porous SUM-81 MOP was successfully incorporated in a series of mixed matrix membranes for CO2/N2 separation, showing impressive performances.

Alkoxy-Functionalized Hydroxamate/Zinc Metal-Organic Frameworks and the Effects of Substituents and Acid Addition on Their Structures

Single crystals of alkoxy-functionalized hydroxamate/zinc metal-organic frameworks (MOFs) were obtained by fixating the hydroxamate moiety via intramolecular hydrogen bonding. The resulting MOF structures depend on the steric demand of the alkoxy groups, whereby the incorporation of bulky isopropyl groups affords porous hydroxamate/zinc MOFs. The topological structures of the isopropyl-substituted MOFs could be controlled by adding acid.

Sacrificial-Hydroxamate-Enabled Sizable Crystallization of Scandium Carboxylate Metal-Organic Frameworks

Starting from labile hydroxamic acid ligands that are strong chelators, here, we implemented a sacrificial modulating strategy to prepare a series of scandium carboxylate metal-organic frameworks. Overcoming conventional syntheses that use excessive carboxylate modulators, the present strategy greatly reduces the organics required and produces large single crystals of several Sc-MOFs for X-ray crystallography.

Coordination-Driven Heterochiral Self-Assembly: Construction of Cd(II) Coordination Polymers with Sorption Behaviors for Iodine and Dyes

A racemic bispyridyl ligand (L) was synthesized via a Schiff base condensation reaction. Four Cd(II) complexes, {[CdL2Cl2]·2DMF}n (1), [CdLI2]n (2), {[CdL2Br2]·4H2O}n (3), and {[CdL2(H2O)2](NO3)2·2CH3OH·8H2O}n (4), were synthesized and further characterized based on this ligand. Single-crystal structures show that the coordination-driven assembly of the bispyridyl ligand with Cd(II) salts bearing different counteranions can lead to multidimensional coordination polymers via a heterochiral self-discrimination process. Complex 1 exists as a one-dimensional (1D) looped chain polymer, and complex 2 exists as a 1D zigzag chain polymer. Complex 3 is a 2D grid coordination polymer, and complex 4 exists as a 3D framework polymer. Furthermore, the iodine sorption capacities of the four complexes were investigated in the solution of n-hexane and water as well as in the iodine steam. The dye sorption behaviors were investigated in water, which showed that complex 2 exhibited good adsorption for crystal violet (CV), while complex 4 had good adsorption capability toward direct yellow 4 (DY).

Poly(p-phenylenediamine)-Coated Metal-Organic Frameworks for High-Performance Sodium-Ion Batteries: The Balance of Capacity and Stability

Metal-organic frameworks (MOFs) with well-defined porous structures and highly active frameworks are considered as promising electrode materials for sodium-ion batteries (SIBs). However, the structure pulverization upon sodiation/desodiation impacts on their practical application in SIBs. To address this issue, poly(p-phenylenediamine) (PPA) was uniformly coated onto the surface of MIL-88A, a typical Fe-based MOF through in situ polymerization initiated by the metal ions (Fe3+) of MIL-88A. Used as an anode material for SIBs, the PPA-coated MIL-88A, denoted as PPA@MIL-88A, showed significantly improved electrochemical performance. A reversible capacity as high as 230 mAh g-1 was achieved at 0.2 A g-1 even after 500 cycles. MIL-88A constructed with electrochemically active Fe3+ and fumaric acid ligands guarantees the high specific capacity, while the PPA polymer coating effectively inhibits the pulverization of MIL-88A. This work provides an efficient strategy for improving the structure and cycling stability of MOFs-based electrode materials.

Water-Soluble Ionic Metal-Organic Polyhedra as a Versatile Platform for Enzyme Bio-immobilization

Metal-organic polyhedra (MOPs) can act as elementary structural units for the design of modular porous materials; however, their association with biological systems remains greatly restricted by their typically low stabilities and solubilities in water. Herein, we describe the preparation of novel MOPs bearing either anionic or cationic groups and exhibiting a high affinity for proteins. Simple mixing of the protein bovine serum albumin (BSA) and ionic MOP aqueous solutions resulted in the spontaneous formation of MOP-protein assemblies, in a colloidal state or as solid precipitates depending on the initial mixing ratio. The versatility of the method was further illustrated using two enzymes, catalase and cytochrome c, with different sizes and isoelectric points (pI's) below and above 7. This mode of assembly led to the high retention of catalytic activity and enabled recyclability. Furthermore, the co-immobilization of cytochrome c with highly charged MOPs resulted in a substantial 44-fold increase of its catalytic activity.

A metal-organic framework surrounded with conjugate acid-base pairs for the efficient capture of Cr(VI) via hydrogen bonding over a wide pH range

Given the large amount of toxic Cr(VI) wastewater from various industries, it is urgent to take effective treatment measures. Adsorption has been regarded as highly desirable for Cr(VI) removal, but the effectiveness of most adsorbents is significantly dependent on pH value, in which precipitous performance drop and even structural collapse generally occur in strong acidic/alkaline aqueous. Thus, maintaining high adsorption performance and structural integrity over a wide pH range is challenging. To efficiently remove Cr(VI), we designed and prepared of an acid-base resistant metal-organic framework (MOF) Zr-BDPO, by introducing weak acid-base groups (-NH-, -N= and -OH) onto the ligand. Zr-BDPO achieved a maximum adsorption capacity of 555.6 mg·g^-1 and retained skeletal structure at pH= 1-11. Interestingly, all these groups can generate conjugate acid-base pairs by means of H⁺ and OH^- in the external solution and then form buffer layer. The removal of Cr(VI) at a broad range of pH values primarily via hydrogen bonds between -NH- and -OH, and the oxoanion species of Cr(VI) is unusual. This strategy that insulating high concentrations of acids and bases and relying on hydrogen bonds to capture Cr(VI) oxoanions provides a new perspective for actual Cr(VI) wastewater treatment.

Exploration of Structured Symmetric Cyclic Peptides as Ligands for Metal-Organic Frameworks

Despite remarkable advances in the assembly of highly structured coordination polymers and metal-organic frameworks, the rational design of such materials using more conformationally flexible organic ligands such as peptides remains challenging. In an effort to make the design of such materials fully programmable, we first developed a computational design method for generating metal-mediated 3D frameworks using rigid and symmetric peptide macrocycles with metal-coordinating sidechains. We solved the structures of six crystalline networks involving conformationally constrained 6 to 12 residue cyclic peptides with C2, C3, and S2 internal symmetry and three different types of metals (Zn2+, Co2+, or Cu2+) by single-crystal X-ray diffraction, which reveals how the peptide sequences, backbone symmetries, and metal coordination preferences drive the assembly of the resulting structures. In contrast to smaller ligands, these peptides associate through peptide-peptide interactions without full coordination of the metals, contrary to one of the assumptions underlying our computational design method. The cyclic peptides are the largest peptidic ligands reported to form crystalline coordination polymers with transition metals to date, and while more work is required to develop methods for fully programming their crystal structures, the combination of high chemical diversity with synthetic accessibility makes them attractive building blocks for engineering a broader set of new crystalline materials for use in applications such as sensing, asymmetric catalysis, and chiral separation.

Synthesis and Biomedical Applications of Highly Porous Metal-Organic Frameworks

In this review, aspects of the synthesis, framework topologies, and biomedical applications of highly porous metal-organic frameworks are discussed. The term "highly porous metal-organic frameworks" (HPMOFs) is used to denote MOFs with a surface area larger than 4000 m² g^-1. Such compounds are suitable for the encapsulation of a variety of large guest molecules, ranging from organic dyes to drugs and proteins, and hence they can address major contemporary challenges in the environmental and biomedical field. Numerous synthetic approaches towards HPMOFs have been developed and discussed herein. Attempts are made to categorise the most successful synthetic strategies; however, these are often not independent from each other, and a combination of different parameters is required to be thoroughly considered for the synthesis of stable HPMOFs. The majority of the HPMOFs in this review are of special interest not only because of their high porosity and fascinating structures, but also due to their capability to encapsulate and deliver drugs, proteins, enzymes, genes, or cells; hence, they are excellent candidates in biomedical applications that involve drug delivery, enzyme immobilisation, gene targeting, etc. The encapsulation strategies are described, and the MOFs are categorised according to the type of biomolecule they are able to encapsulate. The research field of HPMOFs has witnessed tremendous development recently. Their intriguing features and potential applications attract researchers' interest and promise an auspicious future for this class of highly porous materials.

Construction of Cu(I)-Organic Frameworks with Effective Sorption Behavior for Iodine and Congo Red

The assembly of a tetradentate pyridine-derived ligand with CuX has afforded two isostructural Cu(I)-organic frameworks [Cu₂X₂(TBD)·DMF]_n (X = Cl for 1 and Br for 2) in this work. Structural analysis indicates that the compounds feature hybrid layered architectures, and the three-dimensional supramolecular frameworks are finally fabricated through the alternative stacking of adjacent layers wherein large open channels are simultaneously constructed. The chemical stability has been studied showing the excellent skeleton maintenance of the prepared solids in various solvents and even in water. Moreover, the iodine and dye sorption performance for compound 1 has been further tested. The Cu(I)-based metal-organic framework exhibits outstanding sorption and separation abilities on the targeted species, which could be considered as a promising adsorbent with high efficiency and selectivity.

Metal-Organic Polyhedra as Building Blocks for Porous Extended Networks

Metal-organic polyhedra (MOPs) are a subclass of coordination cages that can adsorb and host species in solution and are permanently porous in solid-state. These characteristics, together with the recent development of their orthogonal surface chemistry and the assembly of more stable cages, have awakened the latent potential of MOPs to be used as building blocks for the synthesis of extended porous networks. This review article focuses on exploring the key developments that make the extension of MOPs possible, highlighting the most remarkable examples of MOP-based soft materials and crystalline extended frameworks. Finally, the article ventures to offer future perspectives on the exploitation of MOPs in fields that still remain ripe toward the use of such unorthodox molecular porous platforms.

Mixed-Linker Strategy for the Construction of Metal-Organic Framework Combined with Dyes toward Alcohol Detection

Herein, a N-rich metal-organic framework (MOF) with four kinds of cages, Zn₄(ade)₂(TCA)₂(H₂O) (NENU-1000, Hade = adenine, H₃TCA = 4,4',4″-tricarboxytriphenylamine, NENU = Northeast Normal University), was prepared by the mixed-ligand strategy. Cationic dyes can be selectively absorbed by NENU-1000 at proper concentrations, but not neutral and anionic dyes, which perhaps can be assigned to the N-rich neutral framework of NENU-1000. When NENU-1000 was introduced to a relatively lower concentration of cationic dye solutions (e.g., rhodamine B or basic red 2), the colors of these systems faded quickly. Furthermore, the faded solutions can be used for the detection of methanol and other small alcohol molecules with either the naked eye or common UV-vis spectra. The effect of the length of carbon chain, the position of the -OH group, and the number of the hydroxyl group of the alcohols was explored for the color development rate. In addition, the performance of NENU-1000 in iodine sorption and release was also studied.

Metal-hydrogen-pi-bonded organic frameworks

We report the synthesis and characterization of a new series of permanently porous, three-dimensional metal-organic frameworks (MOFs), M-HAF-2 (M = Fe, Ga, or In), constructed from tetratopic, hydroxamate-based, chelating linkers. The structure of M-HAF-2 was determined by three-dimensional electron diffraction (3D ED), revealing a unique interpenetrated hcb-a net topology. This unusual topology is enabled by the presence of free hydroxamic acid groups, which lead to the formation of a diverse network of cooperative interactions comprising metal-hydroxamate coordination interactions at single metal nodes, staggered π-π interactions between linkers, and H-bonding interactions between metal-coordinated and free hydroxamate groups. Such extensive, multimodal interconnectivity is reminiscent of the complex, noncovalent interaction networks of proteins and endows M-HAF-2 frameworks with high thermal and chemical stability and allows them to readily undergo postsynthetic metal ion exchange (PSE) between trivalent metal ions. We demonstrate that M-HAF-2 can serve as versatile porous materials for ionic separations, aided by one-dimensional channels lined by continuously π-stacked aromatic groups and H-bonding hydroxamate functionalities. As an addition to the small group of hydroxamic acid-based MOFs, M-HAF-2 represents a structural merger between MOFs and hydrogen-bonded organic frameworks (HOFs) and illustrates the utility of non-canonical metal-coordinating functionalities in the discovery of new bonding and topological patterns in reticular materials.

Hydroxamate based transition metal-organic coordination polymers with semiconductive properties

In addtion to carboxylate and N-donor linkers, hydroxamates are a kind of new emerging ligand to form coordination polymers. However, owing to the difficulty in controlling reversible formation of strong...

Palladium-Catalyzed Butoxycarbonylation of Polybromo(hetero)arenes: A Practical Method for the Preparation of (Hetero)arenepolycarboxylates and -carboxylic Acids

The palladium-catalyzed alkoxycarbonylation of polybromo­(hetero)arenes was investigated systematically. The results show that cheap and readily available in situ Pd(OAc)2/rac-BINAP catalyst can catalyze the butoxycarbonylation of various polybromo(hetero)arenes efficiently, and gave (hetero)arenepolycarboxylates with moderate to high yield (59–94%). Using this method, two new compounds, 4,4′-bis(butoxycarbonyl)-1,1′-bi-2-naphthol and dibutyl [2,2′-bipyrimidine]-5,5′-dicarboxylate, are reported for the first time. In addition, the gram-scale preparation of carboxylate and carboxylic acids was successful performed by butoxycarbonylation followed by hydrolysis. This shows the wide scope of substrates and practical applications of the Pd(OAc)2/rac-BINAP catalytic system. Moreover, these carboxylic acids and carboxylates can be used as ligands or structural units to construct MOFs, metal complexes, and COFs etc.

Two-Dimensional Zr/Hf-Hydroxamate Metal-Organic Frameworks

Novel two-dimensional kagome metal-organic frameworks with mononuclear Zr4+/Hf4+ nodes chelated by benzene-1,4-dihydroxamate linkers were synthesized. The MOFs, namely SUM-1, are chemically robust and kinetically favorable, as confirmed by theoretical and...

Permanent Porosity in Hydroxamate Titanium-Organic Polyhedra

Following the synthesis of hydroxamate titanium-organic frameworks, we now extend these siderophore-type linkers to the assembly of the first titanium-organic polyhedra displaying permanent porosity. Mixed-linker versions of this molecular cage (cMUV-11) are also used to demonstrate the effect of pore chemistry in accessing high surface areas of near 1200 m²·g^-1.

An alternative strategy to construct uniform MOFs-Grafted silica core-shell composites as mixed-mode stationary phase for chromatography separation

The preparation of the metal-organic frameworks (MOFs)@silica core-shell microspheres as the stationary phases mainly relied on the method of electrostatic interaction between the metal ions of MOFs and the silanol groups. Herein, the ligands of MOFs were preferentially modified to the surface of silica as connection points and seed crystals to connect or form the MOFs. In this way, the evenness of the MOFs particles on the silica surface was effectively improved, and the prepared composites possessed excellent reproducibility and stability, including acid-base stability. The relative standard deviation of the retention time for repeatability ranged from 0.1% to 0.26% and for stability retention time from 0.3% to 0.6%. Compared with commercial columns, the prepared stationary phase showed enhanced separation selectivity for separation of both hydrophilic and hydrophobic compounds containing alkaloids, nucleosides, antibiotics and alkylbenzenes, etc. The obtained column was used as a matrix for fast separation and analysis of antibiotics in actual samples. In short, the composites showed superior reproducibility, stability and satisfactory separation performance towards a variety of compounds in the studied conditions. It also provided another way to improve the evenness of MOFs particles on the surface of silica and enhance the stability of them under polar conditions.

Porous assembly of an antifungal protein mediated by zinc and sulfonato-calix[8]arene

Controlled protein assembly holds great potential in the fabrication of biohybrid materials. However, the structural diversity and complexity of proteins present an obstacle to controlled assembly. Supramolecular chemistry is a possible solution as it offers tools to mediate self-assembly with molecular precision. This paper deals with the calixarene- and zinc-mediated assembly and crystallization of the histidine-rich Penicillium chrysogenum antifungal protein B (PAFB). We report crystal structures of pure PAFB, PAFB in complex with Zn²⁺, and the ternary complex of PAFB, Zn²⁺ and sulfonato-calix[8]arene (sclx₈). A comparison of the three crystal structures revealed the structural plasticity of PAFB. While the flexible and highly anionic sclx₈ resulted in large molecular weight aggregates of PAFB in solution, diffraction-quality crystals of PAFB-sclx₈ were not obtained. We report crystals of PAFB-Zn²⁺-sclx₈ in which a trinuclear zinc cluster occurred adjacent to a calixarene binding site. Interestingly, the combination of sclx₈ complexation and zinc coordination resulted in a porous framework with channels of circa 2 nm diameter. Detailed analysis of the crystal structure highlighted novel molecular recognition features. This research enriches the set of supramolecular interactions available to promote protein assembly.

Recent advances in metal-organic frameworks as adsorbent materials for hazardous dye molecules

Water is vital for the sustenance of all forms of life. Hence, water pollution is a universal crisis for the survival for all forms of life and a hurdle in sustainable development. Textile industry is one of the anthropogenic activities that severely pollutes water bodies. Inefficient dyeing processes result in thousands of tons of synthetic dyes being dumped in water bodies every year. Therefore, the efficient removal of synthetic dyes from wastewater has become a challenging research field. Owing to their tuneable structure-property aspects, metal-organic frameworks (MOFs) have emerged as promising adsorbents for the adsorptive removal of dyes from wastewater and textile effluents. In this perspective, we highlight recent studies involving the application of MOFs for the adsorptive removal of hazardous dye molecules. We also classify the developed MOFs into cationic, anionic, and neutral framework categories to comprehend their suitability for the removal of a given class of dyes.

Recent developments in organic-inorganic hybrid metal phosphates and phosphites

The design and synthesis of crystalline materials have been a subject of intensive research because of their interesting structures, physicochemical properties, and potential applications. However, the crystalline structure of organic-inorganic hybrid materials collapses to lose the structural features of the original networks and/or frameworks when exposed to different stimuli such as pH, vapor, water, high temperature, and organic solvents. This hampers further studies focusing on practical applications. Although several review articles provide reasonable pathways for the preparation of stable metal-organic frameworks (MOFs) and coordination polymers (CPs), the synthesis and design of stable materials containing organic species remain challenging. In this frontier article, we discuss the development of crystalline MOF, CP, metallophosphate, and metallophosphite materials, and provide a feasible approach for the formation of stable organic-inorganic hybrid compounds that combine MOFs (or CPs) and phosphate (or phosphite) building elements. In addition to their interesting structures, the synthetic strategies and structural stabilities of such hybrid composites are also presented.

A hydrolytically stable cage-based metal–organic framework containing two types of building blocks for the adsorption of iodine and dyes

A metal–organic framework (SCNU-Z4) with high chemical stability in water and common organic solvents showed ability for iodine and dye adsorption.