Porous material for absorption and luminescent detection of aromatic molecules in water

Progress and challenges of metal-organic frameworks-based materials for SR-AOPs applications in water treatment

As environmental problems become more and more severe, sulfate radical (SO₄^-) based advanced oxidation processes (SR-AOPs) are widely recognized for their high removal efficiency of recalcitrant organic pollutants in water. Metal-organic frameworks (MOFs) have attracted wide attention in SR-AOPs due to their outstanding properties (e.g. large surface area, ultra-high porosity, and diversity of material design, etc). Herein, we present an overview of the development and challenges in the synthesis of different types of MOFs, combination of MOFs with other materials (metal centers, conductors, cellulose, etc.) and the construction of catalysts with special structures (core-shell structures and hollow structures) as well as their applications in SR-AOPs for the degradation of organic pollutants. Several review papers have already mentioned the application of a branch of MOFs or simple composites of MOFs in SR-AOP, whereas the latest progresses on the application of MOFs-based materials to SR-AOPs was described rarely. Besides, the degradation mechanism of MOFs as catalysts has not been systematically discussed. To this end, the mechanisms of MOFs and MOF-based materials as catalysts to activate PMS/PS in different systems are analyzed, including radicals and non-radicals pathways. Meanwhile, considering that the research in this field is still in its infancy, a lot of improvements are still needed to effectively promote and implement this technology.

Heterogeneous UV/Fenton-Like Degradation of Methyl Orange Using Iron Terephthalate MIL-53 Catalyst

The synthesis and degradation of methyl orange (MO) in an ultraviolet-assisted heterogeneous Fenton-like process via the iron terephthalate (MIL-53) catalyst are demonstrated. MIL-53 material was characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectra (DR-UV-Vis), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and nitrogen adsorption/desorption isotherms. It was found that the obtained material shares an identical pattern of the MIL-53 structure with high crystallinity and also demonstrates the mesoporous phase with a pore diameter of around 4.2 nm and specific surface area, SBET, of 88.2 m2·g−1. MIL-53 with UV irradiation exhibits high catalytic activity for MO degradation by hydrogen peroxide. The factors affecting the efficiency of MO decomposition including pH of the solution, H2O2 concentration, catalyst dosage, initial MO concentration, and reaction temperature were addressed. The present catalyst is stable after four recycles with slight catalytic activity loss which makes it a potential candidate for environmental restoration.

Three layer-structured cadmium coordination polymers based on flexible 5-(4-pyridyl)-methoxylisophthalic acid: rapid synthesis and luminescence sensing

Three layered Cd-CPs, synthesized by a MW-assisted solvothermal method within two or three minutes, serve as fluorescent sensors for Fe³⁺ ions.

Fluorescence Quenching Investigation of Methyl Red Adsorption on Aluminum-Based Metal-Organic Frameworks

The adsorption of methyl red (MR) isomers (ortho, meta, and para) on metal-organic frameworks (MOFs) was investigated by using a fluorescence quenching technique. All three MR isomers were found to quench the fluorescence of MOFs effectively. Nonlinear fluorescence quenching trends were observed in Stern-Volmer plots. A modified nonlinear Stern-Volmer equation with the concepts of multiple adsorption sites, adsorption strength, and quencher accessibility was successfully adopted to fit the fluorescence quenching data. The fitted parameters were correlated with the structural properties of MRs and MOFs. The order of quenching efficiency was found to be m-MR > p-MR > o-MR for all MOFs. This indicates that MR molecules not only adsorb via carboxylate-metal bonding but also adsorb through π-π interactions between the aromatic rings of MR and linker molecules in MOFs. The position of the carboxylate group in MRs and the structure of the linkers in MOFs are the key factors affecting the fluorescence quenching efficiency.

Study of the mechanoluminescence and ‘aggregation-induced emission enhancement’ properties of a new conjugated oligomer containing tetraphenylethylene in the backbone: application in the selective and sensitive detection of explosive

D–π-A based ‘Aggregation-Induced Emission Enhancement (AIEE)’ active conjugated oligomer (oTPETP) exhibits an abnormal blue shifting mechanoluminescence and selective and sensitive detection of explosive.

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.

Novel Anderson-type [TeMo6O24]6−-based metal–organic complexes tuned by different species and their coordination modes: assembly, various architectures and properties

Four novel Anderson-type polyoxometalate [TeMo₆O₂₄]⁶⁻-based metal–organic complexes were hydrothermally synthesized and characterized, which show fluorescence, electrochemical and photocatalytic properties.

A series of pyridyl-amide-based ZnII/CdII coordination polymers and their polypyrrole-functionalized composite materials for tuning their photocatalytic properties

Six pyridyl-amide-based Zn^II/Cd^II coordination polymers have been solvothermally synthesized and decorated by polypyrrole for tuning their photocatalytic properties under visible irradiation.

Parameterizing and grading hydrolytic stability in metal–organic frameworks

Water stability of MOFs is reviewed including exposure techniques, characterization methods, and ultimately more consistent definitions of water stability.

Layer-structured coordination polymers based on 5-(1H-tetrazol-5-yl)isophthalic acid: structure, sensitization of lanthanide(iii) cations and small-molecule sensing

Compound 1 can serve as a host for encapsulation of Ln³⁺ ions.

Adsorptive separation on metal-organic frameworks in the liquid phase

While much attention of the MOF community has been devoted to adsorption and purification of gases, there is now also a vast body of data on the capability of MOFs to separate and purify liquid mixtures. Initial studies focused on separation of petrochemicals in apolar backgrounds, but the attention has moved now to the separation of complex, e.g. chiral compounds, and to the isolation of biobased compounds from aqueous media. We here give an overview of most of the existing literature, with an accent on separation mechanisms and structure-selectivity relationships.

Engineering lanthanide-optical centres in IRMOF-3 by post-synthetic modification

Infrared emitters based on IRMOF-3 are modified with 2-chloroacetic acid, glyoxylic acid, diethyl (ethoxymethylene)malonate, methyl vinyl ketone, and Eu³⁺& Nd³⁺.

Assembly, structures, photophysical properties and photocatalytic activities of a series of coordination polymers constructed from semi-rigid bis-pyridyl-bis-amide and benzenetricarboxylic acid

Ten metal–organic coordination polymers 1–10 based on semi-rigid bis-pyridyl-bis-amide ligands have been synthesized. The fluorescence sensing and photocatalytic properties of 1–10 have been investigated.

Syntheses, X-ray structures, catalytic activity and magnetic properties of two new coordination polymers of Co(ii) and Ni(ii) based on benzenedicarboxylate and linear N,N′-donor Schiff base linkers

Mixed ligand coordination polymers showing excellent catalytic activity for Knoevenagel condensation reaction.

Seven dicarboxylate-based coordination polymers with structural varieties and different solvent resistance properties derived from the introduction of small organic linkers

Introducing organic molecules as coligands, several coordination polymers with new topologies and remarkable solvent resistance properties have been obtained.

2-D lanthanide–organic complexes constructed from 6,7-dihydropyrido(2,3-d)pyridazine-5,8-dione: synthesis, characterization and photoluminescence for sensing small molecules

The 2-D lanthanide–organic complex [(EuHPDH)(ox)(H₂O)]_n, synthesized under hydrothermal conditions, shows high potential for sensing small molecules by its luminescence properties in different emulsions.

A cationic iridium(iii) complex with aggregation-induced emission (AIE) properties for highly selective detection of explosives

A new AIE-active cationic Ir(iii) complex has been designed and synthesized, which exhibits highly sensitive and selective detection of explosives (TNP).

A two-dimensional Cu(I) framework incorporating the 1-phenyl-1H-1,2,3,4-tetrazole-5-thiol ligand

The new two-dimensional coordination polymer, poly[(μ4-1-phenyl-1H-1,2,3,4-tetrazole-5-thiolato)copper(I)], [Cu(C7H5N4S)]n, has been prepared under solvothermal conditions by reacting CuBr with 1-phenyl-1H-1,2,3,4-tetrazole-5-thiol (Hptt) in an acetonitrile and acetone solution. In the crystal structure, each Cu(I) ion is coordinated by two N atoms and two S atoms from four ptt(-) ligands, and each ptt(-) ligand links four Cu(I) ions to form two-dimensional layers which lie parallel to the (100) plane. These layers stack along the [100] direction via van der Waals interactions.

Solid-state dye-sensitized solar cells from polymer-templated TiO2 bilayer thin films

We report an inexpensive method using solvent-swollen poly(methyl methacrylate) as a sacrificial template for mesoporous titanium oxide thin films with tunable meso/nano morphology. The conversion efficiency reaches 4.2% despite using a solid-state electrolyte, which circumvents the longevity issues of liquid electrolytes. The cells show a large short-circuit photocurrent density of 7.98 mA, open-circuit voltage of 0.78 V, and maximum conversion efficiency of 4.2% under air-mass 1.5 global illumination. At higher titania precursor ratios, nanodisk particles are formed that increase light scattering and double the efficiency over our previous reports. The tunability of the semiconductor morphology and all solid-state nature of the cells makes the method a viable alternative to existing solar cell technology.