Thin-Film Nanocomposite (TFN) Membranes Incorporated with Super-Hydrophilic Metal-Organic Framework (MOF) UiO-66: Toward Enhancement of Water Flux and Salt Rejection

Zirconiumv (IV)-carboxylate metal-organic framework (MOF) UiO-66 nanoparticles were successfully synthesized and incorporated in the polyamide (PA) selective layer to fabricate novel thin-film nanocomposite (TFN) membranes. Compared to unmodified pure polyamide thin-film composite (TFC) membranes, the incorporation of UiO-66 nanoparticles significantly changes the membrane morphology and chemistry, leading to an improvement of intrinsic separation properties due to the molecular sieving and superhydrophilic nature of UiO-66 particles. The best performing TFN-U2 (0.1 wt % particle loading) membrane not only shows a 52% increase of water permeability but also maintains salt rejection levels (∼95%) similar to the benchmark. The effects of UiO-66 loading on the forward osmosis (FO) performance were also investigated. Incorporation of 0.1 wt % UiO-66 produced a maximum water flux increase of 40% and 25% over the TFC control under PRO and FO modes, when 1 M NaCl was used as the draw solution against deionized water feed. Meanwhile, solute reverse flux was maintained at a relatively low level. In addition, TFN-U2 membrane displayed a relatively linear increase in FO water flux with increasing NaCl concentration up to 2.0 M, suggesting a slightly reduced internal concentration polarization effect. To our best knowledge, the current study is the first to consider implementation of Zr-MOFs (UiO-66) onto TFN-FO membranes.

Nanoscaled porphyrinic metal-organic frameworks: photosensitizer delivery systems for photodynamic therapy

The photocytotoxic activity of porphyrin-containing materials including metal-organic frameworks (MOFs) has attracted ever increasing interest. We have developed a simple synthesis of hexagonal PCN-222/MOF-545 nanoparticles, which are powerful in inducing reactive oxygen species-mediated apoptosis of cancer cells upon visible light irradiation. The extent of the cytotoxic effect well correlates with the nanoparticle size and structural instability. High phototoxicity of the presented nanoparticles and their deactivation within several hours open up the door to possible applications in cancer therapy.

Mechanochemical and Conventional Synthesis of Zn(II)/Cd(II) Luminescent Coordination Polymers: Dual Sensing Probe for Selective Detection of Chromate Anions and TNP in Aqueous Phase

Isostructural Zn(II)/Cd(II) mixed ligand coordination polymers (CPs) {[M(IPA)(L)]}_n (CP1 and CP2) built from isophthalic acid (H₂IPA) and 3-pyridylcarboxaldehyde nicotinoylhydrazone (L) were prepared using versatile synthetic routes: viz., diffusion of precursor solutions, conventional reflux methods, and green mechanochemical (grinding) reactions. Both robust CPs synthesized by different routes were characterized by various analytical methods, and their thermal and chemical stability as well as the phase purity was established. Crystallographic studies revealed that CP1 and CP2 are isostructural frameworks and feature a double-lined two-dimensional network composed of Zn²⁺/Cd²⁺ nodes connected through IPA and pillared by the Schiff base ligand L with a double-walled edge. The photoluminescent (PL) properties of CP1 and CP2 have been exploited as dual detection fluorosensors for hexavalent chromate anions (CrO₄^2-/Cr₂O₇^2-) and 2,4,6-trinitrophenol (TNP) because it was observed that the emission intensity of aqueous suspensions of CPs selectively quenches by chromate anions or TNP among large pools of different anions or nitro compounds, respectively. Competitive experiments in the presence of interfering anions/other nitro compounds also revealed no major effect in the quenching efficiency, suggesting the selective detection of hexavalent chromate anions as well as TNP by the LCPs. The limits of detection by CP1 for CrO₄^2-/Cr₂O₇^2- and TNP are 4 ppm/4 ppm and 28 ppb, respectively, whereas the limits of detection by CP2 for the same analytes are 1 ppm/1 ppm and 14 ppb, respectively. A probable mechanism for the quenching phenomena is also discussed.

Imparting surface hydrophobicity to metal-organic frameworks using a facile solution-immersion process to enhance water stability for CO2 capture

The water sensitivity of metal-organic frameworks (MOFs) poses a critical issue for their large-scale applications. One effective method to solve this is to provide MOFs with a hydrophobic surface. Herein, we develop a facile solution-immersion process to deposit a hydrophobic coating on the MOFs' external surface without blocking their intrinsic pores. The water contact angle of the surface hydrophobic (SH) MOFs is ∼146°. The hydrophobic coating not only greatly enhances MOFs' water stability but also provides durable protection against the attack of water molecules. When exposed to liquid water, the SH samples well retain their crystal structure, morphology, surface area and CO₂ uptake capacity. However, the as-synthesized (AS) samples nearly collapse and lose their porosity as well as CO₂ uptake capacity after the same exposure. This study opens up a new avenue for the MOFs' application of gas sorption in the presence of water.

Ni-Based metal–organic framework derived Ni@C nanosheets on a Ni foam substrate as a supersensitive non-enzymatic glucose sensor

Uniform and compact porous Ni@C nanosheet membranes on Ni foam showing remarkable electrocatalytic activity for non-enzymatic glucose sensing.

A new Tb(iii)-functionalized layer-like Cd MOF as luminescent probe for high-selectively sensing of Cr3+

A new layer-like metal–organic framework {[Cd₄(NDIC)₄·5DMF·H₂O]DMF}_n (NDIC = 5-(5-norbonene-2,3-dicarboximide) isophthalic acid) was synthesized by solvothermal method.

Enhanced adsorptive removal of anionic and cationic dyes from single or mixed dye solutions using MOF PCN-222

MOF PCN-222 exhibits excellent adsorption/removal capacities for numerous anionic and cationic dyes individually and together in solutions.

Photochromism, photoluminescence modulation and selective recognition of small molecules of two highly stable dynamic metal–organic frameworks

Two highly stable dynamic Ln-MOFs show photochromism, tunable photoluminescence, and selective recognition of small molecules.

A porous copper–organic framework with intersecting channels and gas adsorption properties

Integration of [CuI2I₂] and [CuII2(COO)₄(H₂O)₂] clusters produces a porous copper–organic framework, exhibiting high H₂ uptake capacity and excellent adsorption selectivity for CO₂ over N₂ and CH₄.

Cu2+ sorption from aqueous media by a recyclable Ca2+ framework

A recyclable Ca-MOF that exchanges Ca²⁺ by Cu²⁺ almost quantitatively and quickly was investigated via batch ion-exchange experiments and utilized as a stationary phase in an ion-exchange column for Cu²⁺ removal from aqueous media.

Metal–organic frameworks based membranes for liquid separation

This Tutorial Review highlights the achievements in the rational design and the latest applications of MOF-based membranes in liquid separation.

Lanthanide functionalized hybrid materials of polyoxometallate based metal–organic frameworks for multi-color luminescence

Lanthanide functionalized hybrids of polyoxometallate based MOF Ln³⁺⊂COK-15 are prepared and display multi-color light, together with a white luminescence (x = 0.3845, y = 0.303) by tuning an appropriate amount of Eu³⁺ and a suitable excitation wavelength.

Metal–organic frameworks with Lewis acidity: synthesis, characterization, and catalytic applications

In this highlight, we review the recent development in the design and synthesis of metal–organic frameworks with Lewis acidity, the characterization techniques of Lewis acid sites, and their applications in heterogeneous catalysis.

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.

Sorption and photodegradation under visible light irradiation of an organic pollutant by a heterogeneous UiO-67–Ru–Ti MOF obtained by post-synthetic exchange

By exchanging metals in a photoactive MOF, it has been possible to obtain a material for the photodegradation of methylene blue.

One, two, and three-dimensional metal–organic coordination polymers derived from enantiopure organic phosphorate: homochirality, water stability and proton conduction

A multifunctional ligand reacts with metal ions to generate three new coordination polymers, where 3 has a high water stability, a moderate proton conductivity and a lower activation energy.