Hierarchical porous amorphous metal-organic frameworks constructed from ZnO/MOF glass composites.

For the first time, hierarchical porous amorphous metal-organic frameworks (HP-aMOFs) containing ultramicropores, micropores, and mesopores were synthesized by etching a composite of MOF glass (agZIF-76) and ZnO using ammonia. These materials show potential applications in the adsorption of C2 hydrocarbons.

Iodine Adsorption-Desorption-Induced Structural Transformation and Improved Ag+ Turn-On Luminescent Sensing Performance of a Nonporous Eu(III) Metal-Organic Framework.

Posttreatment of pristine metal-organic frameworks (MOFs) with suitable vapor may be an effective way to regulate their structures and properties but has been less explored. Herein, we report an interesting example in which a crystalline nonporous Eu(III)-MOF was transferred to a porous amorphous MOF (aMOF) via iodine vapor adsorption-desorption posttreatment, and the resulting aMOF showed improved turn-on sensing properties with respect to Ag+ ions. The crystalline Eu-MOF, namely, Eu-IPDA, was assembled from Eu(III) and 4,4'-{4-[4-(1H-imidazol-1-yl)phenyl]pyridine-2,6-diyl}dibenzoic acid (H2IPDA) and exhibited a two-dimensional (2D) coordination network based on one-dimensional secondary building blocks. The close packing of the 2D networks gives rise to a three-dimensional supramolecular framework without any significant pores. Interestingly, the nonporous Eu-IPDA could absorb iodine molecules when Eu-IPDA crystals were placed in iodine vapor at 85 °C, and the adsorption capacity was 1.90 g/g, which is comparable to those of many MOFs with large BET surfaces. The adsorption of iodine is attributed to the strong interactions among the iodine molecule, the carboxy group, and the N-containing group and leads to the amorphization of the framework. After immersion of the iodine-loaded Eu-IPDA in EtOH, approximately 89.7% of the iodine was removed, resulting in a porous amorphous MOF, denoted as a-Eu-IPDA. In addition, the remaining iodine in the a-Eu-IPDA framework causes strong luminescent quenching in the fluorescence emission region of the Eu(III) center when compared with that in Eu-IPDA. The luminescence intensity of a-Eu-IPDA in water suspensions was significantly enhanced when Ag+ ions were added, with a detection limit of 4.76 × 10-6 M, which is 1000 times that of pristine Eu-IPDA. It also showed strong anti-interference ability over many common competitive metal ions and has the potential to sense Ag+ in natural water bodies and traditional Chinese medicine preparations. A mechanistic study showed that the interactions between Ag+ and the absorbed iodine, the carboxylate group, and the N atoms all contribute to the sensing performance of a-Eu-IPDA.

Porous amorphous metal-organic frameworks based on heterotopic triangular ligands for iodine and high-capacity dye adsorption.

The research on amorphous metal-organic frameworks (aMOFs) is still in its infancy, and designing and constructing aMOFs with functional pores remains a challenge. Two aMOFs based on Co(II) and heterotopic triangular ligands with large conjugated aromatic planes, namely aMOF-1 and aMOF-2, were constructed and characterized by IR, XPS, EA, ICP, XANS and so on. aMOF-1 possesses mesopores, whereas aMOF-2 possesses micropores. The porosity, conjugated aromatic plane and uncoordinated N atoms in the framework allow these aMOFs to adsorb iodine and dyes. The iodine adsorption capacity of aMOF-1 is 3.3 g per g, which is higher than that of aMOF-2 (0.56 g per g), mainly due to the expansion or swelling of aMOF-1 after iodine adsorption. The uptake of cationic dyes by aMOF-2 showed more rapid kinetics and a higher removal rate than that by aMOF-1, mainly due to the difference in the porosity and surface charge. Although the surface charges of aMOF-1 and aMOF-2 are negative, both of them showed significantly faster adsorption kinetics toward anionic dyes, among which methyl orange (MO) and Congo red (CR) can be removed in 5 min. This occurs possibly because the quick adsorption of Na+ ions alters the surface charge of the framework and promotes dye uptake. The adsorption capacities of aMOF-1 for MO and CR reached 921 and 2417 mg g-1, respectively. The correlation data for aMOF-2 are 1042 and 1625 mg g-1, respectively. All adsorption capacities are among the highest compared to many cMOFs. Adsorption in mixed dye solution is found to be charge-dependent, kinetic-dependent, and synergetic in these systems. The porosity, surface charge regulation during adsorption, weak interactions and multiple adsorption processes contribute to the dye adsorption performance.

Encapsulation of a metal-organic cage-based porous salt in silica nanopores.

A metal-organic cage (MOC)-based porous salt composed of cationic Zr-MOC and anionic Cu-MOC was incorporated into SBA-15 nanopores via a two-step impregnation method for the first time. The encapsulated MOC-based porous salt showed improved iodine adsorption capacity when compared with the bulk sample.

Regulating the Porosity and Iodine Adsorption Properties of Metal-Organic Framework Glass via an Ammonia-Immersion Approach.

Metal-organic framework (MOF) glass is a new type of glass material, but it usually lacks sufficient porosity. Thus, regulating the pore structure of MOF glass to improve its adsorption performance is very important. Herein, we found that the porosity of MOF glasses agZIF-62 and agZIF-76 can be regulated via an ammonia-immersion approach. After ammonia immersion, the resulting agZIF-62-NH3 and agZIF-76-NH3 could be maintained in their glass states or converted to their amorphous states, respectively. Their porosity changed according to the gas adsorption experiments. Notably, compared with agZIF-62 and agZIF-76, the iodine uptake capacities for agZIF-62-NH3 and agZIF-76NH3 increased by 12 and 21 times, respectively. This work shows that the subsequent treatment of MOF glass can regulate their adsorption performance.

Strategies for the Construction of Functional Materials Utilizing Presynthesized Metal-Organic Cages (MOCs).

Metal-organic cages (MOCs) that assemble from metal ions or metal clusters and organic ligands have attracted the interest of the scientific community because of their various functional coordination cavities. Unlike metal-organic frameworks (MOFs) with infinite frameworks, MOCs have discrete structures, making them soluble and stable in certain solvents and facilitating their application as starting reagents in the further construction of single components or composite materials. In recent years, increasing progress has been made in this field. In this review, we introduce these works from the perspective of design strategies, and focus on how presynthesized MOCs can be used to construct functional materials. Finally, we discuss the challenges and development prospects in this field.

Fabrication of cellulose derivative coated spherical covalent organic frameworks as chiral stationary phases for high-performance liquid chromatographic enantioseparation.

Porous spherical silica-based chiral stationary phases (CSPs) have been commercially used in the field of chiral separation, however, the scope of their application is, to some extent, limited by the instability of silica towards mobile phase containing strong base or acid. As such, developing new matrix-based CSPs is one of the effective strategies to overcome this bottleneck in studies of chiral separation materials. In this work, we have demonstrated that stable spherical covalent organic frameworks (SCOFs) can be utilized as matrixes for the fabrication of new CSPs for the first time. Specifically, a porous imine-linked SCOF with good crystallinity, large surface area, and high chemical stability is synthesized at room temperature. Then, cellulose-tris (3,5-dimethylphenylcarbamate) (CDMPC), a typical cellulose derivative, is selected as a potential chiral selector and coated onto the robust SCOFs, giving rise to the fabrication of new CDMPC@SCOF CSPs. The as-synthesized stable SCOF-based CSPs are exploited for high-performance liquid chromatographic (HPLC) enantioseparation, showing high resolution abilities for the separation of racemic compounds such as metalaxyl, 1-(1-naphthalenyl)ethanol, epoxiconazol, trans-stilbene oxide, and so on. Moreover, the prepared SCOF-based CSPs exhibit more superior acid and base stability than those of the silica-based CSPs. Our work not only uncovers the great potential of SCOFs as matrixes for constructing novel CSPs, but also expands the application of COFs in the field of enantiomeric separation under harsh base and acid conditions.

Amorphous metal-organic frameworks obtained from a crystalline precursor for the capture of iodine with high capacities.

Two amorphous metal-organic frameworks (aMOFs) were obtained from crystalline Co-MOF (SCNU-Z6) via temperature-induced (aT-SCNU-Z6) and water-immersed (aW-SCNU-Z6) approaches. They exhibited high iodine uptake, with the adsorption capacities of aT-SCNU-Z6 and aW-SCNU-Z6 reaching 2.05 and 5.04 g g-1, respectively. This work is the first report of iodine uptake by aMOFs.

Prostatic carcinosarcoma seven years after radical prostatectomy and hormonal therapy for prostatic adenocarcinoma: A case report.

BACKGROUND: Prostatic carcinosarcoma is a very rare and highly aggressive tumor. It may occur after androgen deprivation therapy (ADT) for adenocarcinoma even after a 7-year interval. CASE SUMMARY: A 66-year-old man presented with recurrent symptoms of gross hematuria and urinary retention. The patient had a previous history of combined radical prostatectomy and ADT for prostate cancer 7 years prior. He received total pelvic exenteration for a recurrent pelvic carcinosarcoma. Pathology and immunostaining revealed a carcinosarcoma of prostatic origin with focal spindled cells and bizarre giant cells. The patient subsequently underwent transverse colostomy for carcinosarcoma recurrence and bowel obstruction 3 mo later. Five months after the diagnosis of prostatic carcinosarcoma, the patient died of multiple organ metastases. CONCLUSION: Prostatic carcinosarcoma after adenocarcinoma is exceedingly rare. ADT mediated transformation and dedifferentiation of the epithelial components may be the origin of this malignancy.

Covalent Cross-Linking of Metal-Organic Cages: Formation of an Amorphous Cationic Porous Extended Framework for the Uptake of Oxo-Anions from Water.

Invited for this month's cover are the collaborating groups of Sheng-Run Zheng and Wei-Guang Zhang from South China Normal University, China. The cover picture shows an amorphous cationic porous metal-organic material that constructed from the covalent linking of large cationic metal-organic cage for the removal of toxic oxo-anions from water with high capacities and rapid kinetics. Read the full text of the article at 10.1002/cplu.202000570.

Covalent Cross-Linking of Metal-Organic Cages: Formation of an Amorphous Cationic Porous Extended Framework for the Uptake of Oxo-Anions from Water.

Cationic amorphous metal-organic cage (MOC)-based materials capable of removing anionic pollutants from water are receiving increasing attention but they are still relatively less reported. Herein, for the first time, a cationic porous MOC-based extended framework, namely, CL-aMOC-1, was constructed by covalent linking of a cationic Pd12 L24 (L=3,5-di-pyridin-4-yl-benzaldehyde) cage with a 1,4-bis(4-aminophenyl)benzene (BAPB) linker. Interestingly, the reaction could be completed within 15 min using an amorphous MOC-based solid (aMOC-1) and BAPB as reactant via a low-temperature solid-state reaction. The CL-aMOC-1 showed improved stability, lower solubility and higher oxo-anion uptake in water compared with the original aMOC-1. The adsorption capacities for CrO4 2- , Cr2 O7 2- and ReO4 - on CL-aMOC-1 were 245.1, 311.5 and 452.5 mg/g, respectively, in which the uptake of Cr(VI)-containing oxo-anions was among the highest compared with those of other metal-organic materials. The CL-aMOC-1 can selectively capture oxo-anions in the presence of competitive anions. It exhibits good reusability as over 85 % of the uptake capacity is retained after 5 cycles. Finally, it shows the ability to remove Cr(VI) ions from electroplating wastewater.

A Mn(II)-MOF with inherent missing metal-ion defects based on an imidazole-tetrazole tripodal ligand and its application in supercapacitors.

A metal-organic framework (MOF), namely SCNU-Z3, based on an imidazole-tetrazole tripodal ligand and Mn(ii), has been constructed. It exhibits a porous 3D framework composed of truncated octahedron cage subunits. Unexpected ligand-induced missing metal-ion defects were observed in the framework. In addition, the application of SCNU-Z3 in a supercapacitor was performed.

Cu-MOF derived Cu-C nanocomposites towards high performance electrochemical supercapacitors.

For the development of asymmetric supercapacitors with higher energy density, the study of new electrode materials with high capacitance is a priority. Herein, the electrochemical behavior of nano copper in alkaline electrolyte is first discovered. It is found that there are two obvious reversible redox symmetric peaks in the range of -0.8-0.2 V in the alkaline electrolyte, corresponding to the conversion of copper into cuprous ions, and then converting cuprous ions into copper ions, indicating that the nanocomposite electrode has the characteristics of a pseudocapacitive reaction. It has a specific capacitance of up to 318 F g-1 at a current density of 1 A g-1, which remains at nearly 100% after 10 000 cycles at the same current density. When assembled with a Ni(OH)2-based electrode into an asymmetric supercapacitor, the device shows excellent capacitive behavior and good reaction reversibility. At 0.4 A g-1, the supercapacitor delivers a reversible capacity of 8.33 F g-1 with an energy density of 13.5 mW h g-1. This study first discovers the electrochemical behavior of nano copper, which can provide a new research idea for further expanding the negative electrodes of supercapacitors with higher energy density.

A new QCM signal enhancement strategy based on streptavidin@metal-organic framework complex for miRNA detection.

Sensitive and selective detection of miRNA is of great significance for the early diagnosis of human diseases, especially for cancers. Quartz crystal microbalance (QCM) is an effective tool for detecting biological molecules; however, the application of QCM for miRNA detection is still very limited. One of the great needs for QCM detection is to further improve the QCM signal. Herein, for the first time, we promote a new signal enhancement strategy for the detection of miRNA by QCM. First, a hairpin biotin-modified DNA was used as a probe DNA, which exposes the biotin site when interacting with target miRNA. Then, a streptavidin@metal-organic framework (SA@MOF) complex formed by electrostatic attractions between SA and a MOF was introduced into the QCM detection system. The SA@MOF complexes serve as both a signal amplifier and a specific recognition element via specific biotin-SA interactions. The strategy was applied to the detection of a colorectal cancer marker, miR-221, by using a stable Zr(IV)-MOF, UiO-66-NH2. The detection linear range was 10 fM-1 nM, the detection limit was 6.9 fM, and the relative standard deviation (RSD) (n = 5) was lower than 10% in both simulated conditions and the real serum environment. Furthermore, the detection limit reached 0.79 aM when coupled with the isothermal exponential amplification reaction (EXPAR).

An unprecedented 2D covalent organic framework with an htb net topology.

A 2D imine-linked COF with a hitherto unreported htb type topology was synthesized from a linear diamine linker and a judiciously designed tetra-aldehyde building block. This work opens the door to the development of COFs with unprecedented topologies and may broaden the scope of COF functional materials by pore size and pore surface engineering.

Homochiral Cu(I) Coordination Polymers Based on a Double-Stranded Helical Building Block from Achiral Ligands: Symmetry-Breaking Crystallization, Photophysical and Photocatalytic Properties.

A pair of homochiral coordination polymers, [Cu(DPT)]n (1M and 1P, HDPT = 3,5-di-4-pyridinyl-2H-tetrazole), were assembled from achiral precursors. Crystal structure analysis showed that they are chiral three-dimensional (3D) coordination polymers based on a new double-stranded helical building block that is composed of two different 1D helices. Interestingly, rare symmetry-breaking crystallization was observed, in which the possibility of obtaining enantio-enriched bulk product with excessive M enantiomers (1-A) was obviously higher than that for P enantiomers (1-B) as demonstrated in multiple, repeated experiments with single-crystal diffraction and vibrational circular dichroism (VCD) spectra. Moreover, compound [Cu(DPT)]n shows good chemical stability in water, with pH values ranging from 3 to 13, as well as in many common organic solvents. Photophysical properties, including thermochromic properties and two-photon excited luminescence, were studied, and the potential for applications in temperature sensing was exhibited. In addition, the photocatalytic degradation of methylene blue in water indicated that compound [Cu(DPT)]n can be used as a photocatalyst.

An Anionic Nanotubular Metal-Organic Framework for High-Capacity Dye Adsorption and Dye Degradation in Darkness.

A metal-organic framework (MOF), named SCNU-Z2, based on a new heterotopic tripodal nitrogen-containing ligand, has been constructed. Due to the replacement of one imidazole group in the reported ligand with one tetrazole group, the charge of the framework is changed from cationic to anionic but retains the same framework structure. The framework consists of tubular channels with a diameter of 1.5 nm and exhibits satisfactory stability in water with a pH range of 3-11. The anionic nature of the framework allows the effective adsorption of the cationic dyes MLB, CV, and RhB with capacities of 455.6, 847.4, and 751.8 mg/g, respectively. Among them, the adsorption capacities for SCNU-Z2 on CV and RhB rank as the highest when compared with other reported MOFs. In contrast, SCNU-Z2 exhibits an extremely low capacity for anionic dyes MO and AO, making it useful for the separation of anionic and cationic dyes based on a charge-dependent mode. Interestingly, SCNU-Z2 can be used to degrade an anionic dye, MB, within 30 min under darkness at room temperature. The apparent activation energy of the dye degradation reaction is calculated to be approximately 18.96 kJ·mol-1, implying that the catalytic reaction of MB can be considered as a low-temperature thermocatalytic reaction in the dark/SCNU-Z2 system.

Stable Hydrazone-Linked Covalent Organic Frameworks Containing O,N,O'-Chelating Sites for Fe(III) Detection in Water.

Two stable crystalline hydrazone-linked covalent organic frameworks (COFs) (Bth-Dha and Bth-Dma) containing functional O,N,O'-chelating sites have been designed and successfully synthesized by the Schiff-base condensation reactions between benzene-1,3,5-tricarbohydrazide (Bth) and 2,5-dihydroxyterephthalaldehyde (Dha) or 2,5-dimethoxyterephthal-aldehyde (Dma), respectively. Bth-Dma exhibits strong fluorescence in the solid state and in an aqueous dispersion, while no fluorescence can be observed for Bth-Dha. Interestingly, the as-synthesized Bth-Dma can be used as a turn-off fluorescence sensor for the Fe(III) ion in aqueous solution with outstanding selectivity and sensitivity. The recognition process can be attributed to the coordination interaction between Fe(III) ion and the O,N,O'-chelating sites in the pore wall of Bth-Dma COF, as verified by X-ray photoelectron spectroscopy and 1H NMR spectroscopy. To the best of our knowledge, this is the first report on the rational design of luminescent COF with predesigned O,N,O'-chelating sites as a fluorescence sensor for highly selective and sensitive metal ion detection. This work may pave the way for designing luminescent COF sensors with functional binding sites for detecting specific metal ions.

Hydrolytically Stable Nanotubular Cationic Metal-Organic Framework for Rapid and Efficient Removal of Toxic Oxo-Anions and Dyes from Water.

Cationic framework materials capable of removing anionic pollutants from wastewater are highly desirable but relatively rarely reported. Herein, a cationic MOF (SCNU-Z1-Cl) possessing tubular channels with diameter of 1.5 nm based on Ni(II) and a nitrogen-containing ligand has been synthesized and applied to capture hazardous anionic contaminants from water. The SCNU-Z1-Cl exhibits high BET surface area of 1636 m2/g, and shows high hydrolytically stability in pH range from 4 to 10. Owing to the large tubular channels and the uncoordinated anions in the framework, the aqueous-phase anion-exchange applications of SCNU-Z1-Cl were explored with environmentally toxic oxo-anions including CrO42-, Cr2O72-, MnO4-, and ReO4-, and organic dyes. The adsorption of oxoanions exhibits high uptake kinetics and the adsorption capacities of CrO42-, Cr2O72-, MnO4-, and ReO4- are 126, 241, 292, and 318 mg/g, respectively, which were some of the highest values in the field of MOF/COF. In additional, the selectively is high when other concurrent anions are exist. The anionic dyes with different sizes including methyl orange, acid orange A, congo red, as well as methyl blue can be adsorbed by SCNU-Z1-Cl in few minutes to about 1 h. The adsorption capacities for them are 285, 180, 585, and 262 mg/g, respectively. In contrast, the adsorption kinetics for catinionic dyes with different sizes is obviously lower and exhibit a size-selectively adsorption that only cationic dye with suitable size (rhodamine B) can be adsorbed by SCNU-Z1-Cl. Consequently, SCNU-Z1-Cl can sepearate organic dyes in three different modes: size-dependent, charge-dependent, and kinetics-dependent selective adsorption. The excellent adsorption and separation properties of SCNU-Z1-Cl is attribute to the cationic framework, large tubular channel, as well as the high positive Zeta potential.

Construction of a hydrazone-linked chiral covalent organic framework-silica composite as the stationary phase for high performance liquid chromatography.

Covalent organic frameworks (COFs), as an emerging class of crystalline porous organic polymers, have great potential for applications in chromatographic separation owning to their fascinating crystalline structures and outstanding properties. However, development of COF materials as novel stationary phases in high performance liquid chromatography (HPLC) is just in its infancy. Herein, we report the design and construction of a new hydrazone-linked chiral COF, termed BtaMth COF, from a chiral hydrazide building block (Mth) and present a one-pot synthetic method for the fabrication of BtaMth@SiO2 composite for HPLC separation of isomers. The as-synthesized BtaMth chiral COF displays good crystallinity, high porosity, as well as excellent chemical stability. Meanwhile, the fabricated HPLC column by using BtaMth@SiO2 composite as the new stationary phase exhibits high resolution performances for the separation of positional isomers including nitrotoluene and nitrochlorobenzene, as well as cis-trans isomers including beta-cypermethrin and metconazole. Additionally, some effects such as the composition of the mobile phase and column temperature for HPLC separations on the BtaMth@SiO2 packed column also have been studied in detail. The successful applications indicate the great potentials of hydrazone-linked chiral COF-silica composite as novel stationary phase for the efficient HPLC separation.