Two novel nitrogen-rich metal-organic nanotubes: syntheses, structures and selective adsorption toward rare earth ions.

The construction and development of metal-organic nanotubes (MONTs) with nanoscale interior channel diameters for potential applications is of great interest. An angular nitrogen-rich ligand, 3,6-bis(2-ethylimidazole)-2-methylpyrimidine (beim-CH3), was designed to construct MONTs by coupling with the V-shaped carboxylate ligands of benzophenone 4,4'-dicarboxylic acid (H2bpndc) and 4,4'-oxybisbenzoic acid (H2obba). Two new MONTs were synthesized and named NCD-166 ([Zn(bpndc)(beim-CH3)]·H2O) and NCD-167 ([Zn(obba)(beim-CH3)]·H2O), and they were isostructural and have almost identical tube inner diameters of approximately 1.76 nm. Benefiting from the abundantly exposed nitrogen and oxygen atoms in their tube walls and open nanoporous channels, they display superior adsorption capacities for Eu3+ (150.90 mg g-1) and high adsorption selectivity (>96%) in the low-concentration solutions. Additionally, it was revealed that the adsorption effect of ether oxygen on rare earth elements was significantly better than that of carbonyl oxygen. The adsorption isotherm conformed to the Langmuir model and the adsorption kinetics obeyed the pseudo-second-order model. These results clearly indicate that such novel MONTs are favorable sorbents for REEs.

Synergy between plasmonic and sites on gold nanoparticle-modified bismuth-rich bismuth oxybromide nanotubes for the efficient photocatalytic CC coupling synthesis of ethane.

The photocatalytic reduction of carbon dioxide (CO2) to fossil fuels has attracted widespread attention. However, obtaining the high value-added hydrocarbons, especially C2+ products, remains a considerable challenge. Herein, gold (Au) nanoparticle-modified bismuth-rich bismuth oxybromide Bi12O17Br2 nanotube composites were designed and tested. Au nanoparticles act as electron traps and thermal electron donors that promote the efficient separation and migration of carriers to form the C2+ product. As a result, compared with the pure Bi12O17Br2 nanotubes, Au@Bi12O17Br2 composites can not only produce the carbon monoxide (CO) and methane (CH4), but also covert CO2 into ethane (C2H6). In this study, Au@Bi12O17Br2-700 was used to obtain a C2H6 production rate of 29.26 µmol h-1 g-1. The selectivities during a 5-hour test reached 94.86% for hydrocarbons and 90.81% for C2H6. The proposed approach could be used to design high-performance photocatalysts to convert CO2 into high value-added hydrocarbon products.

Step by Step Construction of Multifunctional Hollow Double Shell MNPs@MOF as a Powerful Tandem/Cascade Catalyst.

The development of efficient heterogeneous catalysts for one-pot tandem/cascade synthesis of imines remains meaningful and challenging. Herein, we constructed an Au/MOF catalyst featured hollow and double MOF shell nanostructure. Owing to its structural merits and acid-basic nature, the as-synthesized Void|(Au)ZIF-8|ZIF-8 catalyst exhibited an enhanced synergistically catalytic performance for tandem catalytic synthesis of imines from benzyl alcohol and aniline under air atmosphere and solvent-free condition. Its 170.16 h-1 of turnover frequency (TOF) was 2.5 times higher than that of the reported catalyst with the highest TOF value.

Mechanism on redistribution synthesis of dichlorodimethylsilane by AlCl3/ZSM-5(3T)@γ-Al2O3 core-shell catalyst.

The redistribution method plays an important role in addressing the issue of organosilicon by-products in the direct synthesis of dichlorodimethylsilane, and the redistribution mechanism is still a topic of debate. The redistribution mechanism by the ZSM-5(3 T)@γ-Al2O3 core-shell catalyst and post-modified AlCl3/ZSM-5(3 T)@γ-Al2O3 catalyst was technically performed using the Density functional theory (DFT) at the level of B3LYP/6-311 + + G(3df,2pd). The results show that no. 1 active site of ZSM-5(3 T)@γ-Al2O3 core-shell structure has a significant effect on the activity of the catalyst. Indicating that the active center involved in the reaction is H provided by the Al-O-H bond, which is an obvious catalytic active center of Bronsted acid. Furthermore, the post-modified AlCl3/ZSM-5(3T)@γ-Al2O3 catalyst is in more favor of redistribution reaction comparing with the ZSM-5(3 T)@γ-Al2O3 core-shell catalyst. It ascribes to the robust Lewis site of aluminum chloride favorable modification. The redistribution synthesis mechanism of dichlorodimethylsilane on the ZSM-5(3 T)@γ-Al2O3 core-shell catalyst and post-modified AlCl3/ZSM-5(3 T)@γ-Al2O3 catalyst had been investigated by using the Density functional theory (DFT) method at the level of B3LYP/6-311 + + G(3df,2pd). The former active center was Bronsted acidic center, while the latter one was Lewis acidic center, ascribing to the Lewis site of aluminum chloride favorable modification. The catalytic activity of the post-synthesis AlCl3/ZSM-5(3 T)@γ-Al2O3 catalyst completely was consistent with experimental results.

Chiral Yolk-Shell MOF as an Efficient Nanoreactor for Asymmetric Catalysis in Organic-Aqueous Two-Phase System.

It remains a great challenge to introduce large and efficient homogeneous asymmetric catalysts into MOFs and other microporous materials as well as retain their degrees of freedom. Herein, a new heterogeneous strategy of homogeneous chiral catalysts is proposed, that is, to construct a yolk-shell MOFs-confined, large-size, and highly efficient homogeneous chiral catalyst, which can be used as a nanoreactor for asymmetric catalytic reactions.

Supramolecular organogels fabricated with dicarboxylic acids and primary alkyl amines: controllable self-assembled structures.

Supramolecular organogels are soft materials comprised of low-molecular-mass organic gelators (LMOGs) and organic liquids. Owning to their unique supramolecular structures and potential applications, LMOGs have attracted wide attention from chemists and biochemists. A new "superorganogel" system based on dicarboxylic acids and primary alkyl amines (R-NH2) from the formation of organogels is achieved in various organic media including strong and weak polar solvents. The gelation properties of these gelators strongly rely on the molecular structure. Their aggregation morphology in the as-obtained organogels can be controlled by the solvent polarity and the tail chain length of R-NH2. Interestingly, flower-like self-assemblies can be obtained in organic solvents with medium polarity, such as tetrahydrofuran, pyridine and dichloromethane, when the gelators possess a suitable length of carbon chain. Moreover, further analyses of Fourier transformation infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy reveal that the intermolecular acid-base interaction and van der Waals interaction are critical driving forces in the process of organogelation. In addition, this kind of organogel system displays excellent mechanical properties and thermo-reversibility, and its forming mechanism is also proposed.

Engineering nanoporous organic frameworks to stabilize naked Au clusters: a charge modulation approach.

A simple charge modulation approach has been developed to stabilize naked Au clusters on a nanoporous conjugated organic network. Through engineering pore walls with regulated charges, the controllable growth of Au nanoclusters has been realized. The resulting supported catalyst exhibits excellent performance in the aerobic oxidation of alcohols.

Superacid-promoted synthesis of highly porous hypercrosslinked polycarbazoles for efficient CO2 capture.

A superacid-promoted "knitting" strategy has been developed for the generation of a novel family of hypercrosslinked nanoporous polycarbazoles for efficient CO2 capture. Using trifluoromethanesulfonic acid, a Brønsted superacid, we demonstrate the facile and rapid synthesis of highly porous polycarbazoles with BET surface areas as high as 1688 m2 g-1, and capable of adsorbing 3.5 mmol g-1 of CO2 at 298 K and 1 bar. This impressive result bestows the material with the highest CO2 uptake capacity for all nanoporous carbazolic polymers and ranks among the best by known porous organic polymers under this condition. This innovative approach affords a metal-free alternative to Friedel-Crafts alkylation, and may open up new possibilities for the rational design and synthesis of new hypercrosslinked nanoporous organic networks for carbon capture.

Pd-Metalated Conjugated Nanoporous Polycarbazoles for Additive-Free Cyanation of Aryl Halides: Boosting Catalytic Efficiency through Spatial Modulation.

Transition-metal-catalyzed cyanation of aryl halides is a common route to benzonitriles, which are integral to many industrial procedures. However, traditional homogeneous catalysts for such processes are expensive and suffer poor recyclability, so a heterogeneous analogue is highly desired. A novel spatial modulation approach has been developed to fabricate a heterogeneous Pd-metalated nanoporous polymer, which catalyzes the cyanation of aryl halides without need for ligands. The catalyst displays high activity in the synthesis of benzonitriles, including high product yields, excellent stability and recycling, and broad functional-group tolerance.

Enhanced selective adsorption of CO2 on nitrogen-doped porous carbon monoliths derived from IRMOF-3.

The N-doped porous carbon monoliths prepared by direct carbonization of IRMOF-3, through an in situ activation and self-templating process, were found to exhibit significantly enhanced performance for the selective adsorption of CO2 compared to pristine IRMOF-3. The transformation from the microporous structure to the meso-macroporous structure opens the pathway for CO2 to more easily access the nitrogen anchors.