Water-resistant porous coordination polymers for gas separation

Base-Resistant Ionic Metal-Organic Framework as a Porous Ion-Exchange Sorbent

A systematic approach has been employed to obtain a hydrolytically stable cationic metal-organic framework (MOF). The synthesized two-dimensional Ni(II)-centered cationic MOF, having its backbone built from purely neutral N-donor ligand, is found to exhibit uncommon resistance over wide pH range, particularly even under highly alkaline conditions. This report presents a rare case of a porous MOF retaining structural integrity under basic conditions, and an even rarer case of a porous cationic MOF. The features of stability and porosity in this ionic MOF have been harnessed for the function of charge- and size-selective capture of small organic dye through ion-exchange process across a wide pH range.

Finely Controlled Stepwise Engineering of Pore Environments and Mechanistic Elucidation of Water-Stable, Flexible 2D Porous Coordination Polymers

Two porous coordination polymers (PCPs) with different topologies (NTU-19: sql and NTU-20: dia) underwent finely controlled, stepwise crystal conversions to yield a common water-stable, flexible 2D framework (NTU-22: kgm). The crystal conversions occurred directly at higher temperature via the 3D intermediate (NTU-21: nbo), which could be observed at lower temperature. The successful isolation of the intermediate product of NTU-21, characterization with in situ PXRD and UV/Vis spectra were combined with DFT calculations to allow an understanding of the dynamic processes at the atomic level. Remarkably, breakthrough experiments demonstrate NTU-22 with integral structural properties allowed significant CO₂ /CH₄ mixture separation.

Modeling Gas Flow Dynamics in Metal-Organic Frameworks

Modeling fluid flow dynamics in metal organic frameworks (MOFs) is a required step toward understanding mechanisms of their activity as novel catalysts, sensors, and filtration materials. We adapted a lattice Boltzmann model, previously used for studying flow dynamics in meso- and microporous media, to the nanoscale dimensions of the MOF pores. Using this model, rapid screening of permeability of a large number of MOF structures, in different crystallographic directions, is possible. The method was illustrated here on the example of an anisotropic MOF, for which we calculated permeability values in different flow directions. This method can be generalized to a large class of MOFs and used to design MOFs with the desired gas flow permeabilities.

A 3D Stable Metal⁻Organic Framework for Highly Efficient Adsorption and Removal of Drug Contaminants from Water

We herein selected a 3D metal–organic framework decorated with carboxylate groups as an adsorbent to remove the pharmaceutical molecules of diclofenac sodium and chlorpromazine hydrochloride from water. The experiment aimed at exploring the effect factors of initial concentration, equilibrium time, temperature, pH and adsorbent dosage on the adsorption process. The adsorption uptake rate of the diclofenac sodium is much higher than that of the chlorpromazine hydrochloride. This paper presents the high adsorption capacity of diclofenac sodium, in which porous MOFs are used for the removal of drug contaminants from water. According to linear fitting with adsorption isotherm equation and kinetic equations, diclofenac sodium conforms to the Langmuir model and pseudo-first-order kinetic equation, while chlorpromazine hydrochloride accords with the Temkin model and pseudo-second-order kinetic equation. The results of the study indicate that the title compound could be a promising hybrid material for removing diclofenac sodium and chlorpromazine hydrochloride from wastewater.

Design and synthesis of multifunctional metal-organic zeolites

Metal-organic zeolites (MOZs) are an important branch of metal-organic frameworks (MOFs) and combine the advantages of zeolites and MOFs, such as high surface area and porosity as well as the exceptional stability of zeolites, which would have a significant impact on catalysis chemistry, inorganic chemistry, coordination chemistry, materials science and other areas. In this review, we focus on the recent advances in MOZs with a brief outline of the most prominent examples. In particular, we highlight the basic principles of the design and synthesis approaches toward the construction of MOZs. Obeying the principle of charge matching, tuning tetrahedral metal centers, using enlarged tetrahedral building units as clusters, introducing functional groups into ligands, and combining traditional inorganic TO₄ sites in MOZs enable the final materials with diverse topological structures to exhibit superior performance for various applications, such as gas sorption/separation, catalysis, enantio-selectivity, luminescence, etc.

Ph-Directed Assembly of Two 2D Copper(II) Coordination Polymers Based on Mixed Benzenetetracarboxylate and 1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-Tetrafluorobenzene Ligands: Syntheses, Structures and Properties

Two new Cu(II) coordination polymers [Cu(Fbtx)(H2btec)(H2O)2]n and {[Cu(Fbtx)(btec)0.5(H2O)2]·H2O}n have been synthesised by hydrothermal reactions of Cu(II) nitrate with 1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-tetrafluorobenzene (Fbtx) and 1,2,4,5-benzenetetracarboxylic acid (H4btec) under different pH conditions. The first complex has a two-dimensional four-connected layer structure with a 44-sql topology, whereas the second has a two-dimensional three-connected brick-wall network. The luminescence properties of the complexes in the solid state and their thermal stabilities have also been studied.

Controlled flexibility of porous coordination polymers by shifting the position of the –CH3 group around coordination sites and their highly efficient gas separation

By adjusting the position of the methyl group, we found significant changes in the structural flexibility of the obtained PCPs, which also showed good gas separation ability.

An unprecedented water stable acylamide-functionalized metal–organic framework for highly efficient CH4/CO2 gas storage/separation and acid–base cooperative catalytic activity

HNUST-8 exhibits water stable, efficient CH₄/CO₂ storage and separation, acid–base cooperative catalytic activity in a tandem deacetalization Knoevenagel densation.

2D and 3D mixed MII/CuIImetal–organic frameworks (M = Ca and Sr) withN,N′-2,6-pyridinebis(oxamate) and oxalate: preparation and magneto-structural study

Heterobimetallic coordination polymers with either antiferro- of ferromagnetic interactions are described herein.

Coordination ability of amino acid hydrazide ligands and their influence on magnetic properties in copper(ii) coordination polymers

Copper(ii) coordination polymers constructed from newly synthesized amino acid hydrazides and 4,4′-bipyridine exhibit antiferromagnetic ordering mediated through hydrazide bridges.

Syntheses of copper–iodine cluster-based frameworks for photocatalytic degradation of methylene blue

Cu–I cluster-based MOFs show a broad range of absorption in the visible region and exhibit excellent photocatalytic degradation of methylene blue dye under visible light.

Rational construction of a stable Zn4O-based MOF for highly efficient CO2 capture and conversion

An exceptionally stable Zn₄O-MOF has been rationally synthesized, which exhibits high CO₂ capture and efficient catalytic conversion for CO₂ cycloaddition with epoxides under mild conditions.

Mechanical Synthesis of COF Nanosheet Cluster and Its Mixed Matrix Membrane for Efficient CO2 Removal

Covalent organic framework (COF) membranes used for selective removal of CO₂ were believed as an efficient and low-cost solution to energy and environmental sustainability. In this study, the amide modified COF nanosheet cluster with a 2D structure was facilely prepared through solid reaction, exhibiting good adsorption-based CO₂ selectivity (223 at 273 K and 90 at 298 K) toward N₂. Remarkably, the mixed matrix membrane (MMM) that consists of a lesser amount of COF filler (1 wt %) shows promising CO₂/N₂ gas selectivity (∼64). In addition, the competitive adsorption prompts the selectivity to ∼72 under an equimolar CO₂/N₂ mixture, which surpasses the values of all reported COF membranes. It is worth to note that the binary gas separation is stable during 120 h.

Prussian Blue Analogues for the Separation of Hydrocarbons in Humid Conditions

The relative affinity of a series of Prussian Blue analogues presenting various chemical compositions for the adsorption of different gases, such as water vapor and hydrocarbons, was studied. The ability of Co[Co^III(CN)₆]_0.66·5.2H₂O for the separation of hydrocarbons in a humid atmosphere was demonstrated.

A mesoporous (3,36)-connected txt-type metal–organic framework constructed by using a naphthyl-embedded ligand exhibiting high CO2 storage and selectivity

A highly mesoporous (3,36)-connected txt-type metal–organic framework with a naphthalene-embedded ligand was successfully synthesized with high CO₂ storage capacity and selectivity.

Pre-design and synthesis of a five-fold interpenetrated pcu-type porous coordination polymer and its CO2/CO separation

The first five-fold interpenetrated PCP with pcu topology and high porosity was rationally designed and prepared, which showed high separation potential of CO₂/CO mixtures.

Designing porous electronic thin-film devices: band offsets and heteroepitaxy

Increasing numbers of electrically active porous framework materials are being reported, with conductivities that make them attractive for technological applications. As design strategies for efficient carrier transport emerge, the next challenge is to incorporate the materials into a functioning device. In thin-film devices interface effects are of critical importance to overall function. In this article we present a method to identify compatible materials combinations to achieve mechanically robust, electronically optimal pairings. The computational screening is based on a two-step procedure: (i) matching of lattice constants to ensure interfaces with minimal epitaxial strain and therefore maximal mechanical and chemical stability; (ii) matching of absolute electron energies to construct energy-band-alignment diagrams, which can be used to screen for particular electronic applications. We apply the methodology to search for zeolitic imidazolate framework (ZIF) type materials that are compatible with native metal electrodes. The procedure allows us to predict simple routes for electrochemical deposition of ZIFs for application as conductive porous electrodes.

Fabrication of morphology-preserved microporous carbon from a zeolitic-like porous coordination polymer

A new zeolitic-like microporous coordination polymer (PCP), [Zn₂(L)·2H₂O]·xguest, was firstly converted to morphology-preserved carbon rods with exclusive micropores and a large surface area for selective gas capture.

Separation/purification of ethylene from an acetylene/ethylene mixture in a pillared-layer porous metal–organic framework

A 3D pillared-layer porous framework with narrow channels decorated with polar pore surfaces has been developed for efficient removal of C₂H₂ from a C₂H₂/C₂H₄ mixture at RT.

Metal–organic frameworks: functional luminescent and photonic materials for sensing applications

This review summarizes the diverse routes to derive sensing applications from suitably functionalized and crystal-engineered metal–organic framework (MOF) materials, either by fluorometric responses, or based on photonic crystal-based signal transduction.