A Microporous Anionic Metal-Organic Framework for Sensing Luminescence of Lanthanide(III) Ions and Selective Absorption of Dyes by Ionic Exchange

A Series of Lanthanide-Germanate Oxo Clusters Decorated by 1,10-Phenanthroline Chromophores

A series of lanthanide-germanate oxo clusters, [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆]·2H₂O [Ln = Dy (1a) and Er (1b); T = -CH₂CH₂COO^- group; phen = 1,10-phenanthroline], [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆]·2phen·16H₂O [Ln = Sm (2a), Eu (2b), and Gd (2c)], and [Ho₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₄]·2phen·13H₂O (3), have been hydrothermally synthesized from the reactions of bis(carboxyethylgermanium sesquioxide) and Ln₂O₃ with auxiliary phen chromophores. Compounds 1a and 1b consist of cage clusters [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆] and free H₂O molecules, where cage clusters are arranged in a CsCl type, while compounds 2a-2c consist of cage clusters [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆], free phen, and free H₂O molecules, where cage clusters are arranged in a NaCl type. Compound 3 consists of the one-dimensional neutral chain [Ho₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₄]_n and free H₂O molecules. These compounds provide the first examples of p-f heterometallic [Ge-O-Ln] oxo clusters decorated by phen chromophores. The photoluminescent and magnetic properties of all compounds have been investigated.

Construction of a Multi-Cage-Based MOF with a Unique Network for Efficient CO2 Capture

As a kind of MOFs, cage-based MOFs usually carry large voids and small windows, which are advantageous to the storage of small molecules that remain kinetically trapped inside the cages (confinement effect). By adjusting the size of windows via reticular synthesis, the cage-based MOFs can selectively capture and separate the suitable size molecules. Here, considering angle-directed and face-directed strategies, a novel multicage-based MOF NUM-3 with a new (3,4,5)-connected topology was successfully constructed in the mixed-ligands assembly. In the framework of NUM-3, there exist four different kinds of cages, which exhibit diverse polyhedral configurations. The four kinds of cages in the order ABCDDCBA as the minimum repeat unit form a 1D tortuous channel along the c axis. Based on the structure characteristics that the 1D channel exhibits different inner diameter (from 4.0 to13.0 Å), NUM-3a (actived NUM-3) can capture CO₂ over C₂H₄ and C₂H₆ by the size selectivity (the empirical kinetic diameters: CO₂ < C₂H₄ < C₂H₆). In addition, it also exhibits commendable selectivity for CO₂ over N₂ and CH₄.

Nanocomposite Deposited Membrane for Oil-in-Water Emulsion Separation with in Situ Removal of Anionic Dyes and Surfactants

The decontamination of various pollutants including oils, organic dyes, and surfactants from water is an unprecedented issue throughout the world. A facile filtration process for in situ multifunctional water purification by employing a low-cost and easy-made catechol-polyethylenimine (PEI) nanocomposite deposited membrane has been designed. In combination with the intrinsic hydrophilicity of amino-rich groups, the resultant membrane possesses superhydrophilicity and underwater superoleophobicity, which is simultaneously advantageous for capturing anionic pollutants due to the electrostatic interaction. Such membrane can be successfully used for sundry surfactant-stabilized oil-in-water emulsions separation and pH-controllable removal of water-soluble dyes and the remaining surfactants at the same time. The excellent characteristics, i.e., fabrication protocol that is easy to scale up, better alkaline resistance, selectively controllable removal ability of anionic dyes, and surfactants with unaltered adsorption performance over 30 consecutive adsorption-desorption-washing cycles, will facilitate its versatility and practicability in environmental remediation and wastewater purification.

Luminescent sensing and photocatalytic degradation properties of an uncommon (4,5,5)-connected 3D MOF based on 3,5-di(3′,5′-dicarboxylphenyl)benzoic acid

An uncommon microporous MOF 1 used as fluorescent chemosensor for NACs and as photocatalyst.

Solvent-dependent selective cation exchange in anionic frameworks based on cobalt(ii) and triphenylamine linkers: reactor-dependent synthesis and sorption properties

Two anionic cobalt(ii) MOFs were obtained dependent on the reactor design and show a solvent-dependent cation exchange leading to a remarkable increase in the surface area of post-synthetic modified materials.

Synthesis and adsorption properties of [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites

Multifunctional [Cu(L)₂(H₂O)]H₂[Cu(L)₂(P₂Mo₅O₂₃)]·4H₂O/Fe₃O₄ (HL = pyridine-2-carboxamide) nanocomposites were successfully synthesized by combining [Cu(L)₂(H₂O)]H₂[Cu(L)₂(P₂Mo₅O₂₃)]·4H₂O and Fe₃O₄ nanoparticles.

Post-synthetic ion-exchange process in nanoporous metal–organic frameworks; an effective way for modulating their structures and properties

In this review paper, we considered all of the reports on the ion-exchange process which occur in the pores of MOFs. A comparison between MOFs before and after-exchange process and their applications were addressed.

Fabrication of a new metal–organic framework for sensitive sensing of nitroaromatics and efficient dye adsorption

Theoretical calculations indicate that the luminescence quenching in 1 in the presence of NACs can be attributed to an electron and resonance energy transfer between the MOF 1 and nitro analytes.

A non-interpenetrating lead-organic framework with large channels based on 1D tube-shaped SBUs

A 3D open MOF based on 1D infinite tube-shaped SBUs shows efficient adsorption of I₂ and selective adsorption of some dyes containing the SO₃⁻ group.

Guest dependent structure and acetone sensing properties of a 2D Eu3+ coordination polymer

A new 2D Eu³⁺ coordination polymer 1 has been constructed and investigated with its acetone sensing properties. In addition, the desolvated sample 1a reveals enhanced sensing sensitivity compared with that of 1 owing to its flexible structure.

Pd-catalyzed selective N(3)-ortho C–H arylation of 1,4-disubstituted 1,2,3-triazoles

Pd(OAc)₂-catalyzed direct C–H arylation of an arene triazole template has been explored using the triazole ring as a directing group.

An uncommon 3D 3,3,4,8-c Cd(ii) metal–organic framework for highly efficient luminescent sensing and organic dye adsorption: experimental and theoretical insight

A stable 3D Cd(ii) MOF used as chemosensor and adsorbent for dyes in wastewater, which exhibited excellent adsorption performance and selectivity.

Microporous rod metal–organic frameworks with diverse Zn/Cd–triazolate ribbons as secondary building units for CO2 uptake and selective adsorption of hydrocarbons

Three rod MOFs exhibiting remarkable CO₂ uptake and high CO₂ and C₂-hydrocarbons over CH₄ selectivity, as well as high isosteric heat of adsorption for C₂H₂.

An anionic metal–organic framework with ternary building units for rapid and selective adsorption of dyes

JLU-Liu39with ternary building units including a rare hexa-nuclear [Cu₆O₂(SO₄)₆] cluster, a classical paddlewheel and a hetero-N, O donor ligand was synthesized. Owing to the ionic framework and large pore volume,JLU-Liu39shows rapid and selective adsorption of organic dyes.

Immobilization of Polyoxometalate in the Metal-Organic Framework rht-MOF-1: Towards a Highly Effective Heterogeneous Catalyst and Dye Scavenger

A series of three remarkable complexes [PMo₁₂O₄₀]@[Cu₆O(TZI)₃(H₂O)₉]₄·OH·31H₂O (H₃TZI = 5-tetrazolylisophthalic acid; denoted as HLJU-1, HLJU = Heilongjiang University), [SiMo₁₂O₄₀]@[Cu₆O(TZI)₃(H₂O)₉]₄·32H₂O (denoted as HLJU-2), and [PW₁₂O₄₀]@[Cu₆O(TZI)₃(H₂O)₆]₄·OH·31H₂O (denoted as HLJU-3) have been isolated by using simple one-step solvothermal reaction of copper chloride, 5-tetrazolylisophthalic acid (H₃TZI), and various Keggin-type polyoxometalates (POMs), respectively. Crystal analysis of HLJU 1−3 reveals that Keggin-type polyoxoanions have been fitted snuggly in the cages of rht-MOF-1 (MOF: metal−organic framework) with large cell volume in a range of 87968−88800 ų and large pore volume of about 68%. HLJU 1–3 exhibit unique catalytic selectivity and reactivity in the oxidation of alkylbenzene with environmental benign oxidant under mild condition in aqueous phase as well as the uptake capacity towards organic pollutants in aqueous solution.

Zr-based metal–organic frameworks: design, synthesis, structure, and applications

This review summarizes the advances in the study of Zr-based metal–organic frameworks in terms of their design, synthesis, structure, and potential applications.

A unique multi-functional cationic luminescent metal–organic nanotube for highly sensitive detection of dichromate and selective high capacity adsorption of Congo red

In this work a flexible multi-dentate 1-(4-aminobenzyl)-1,2,4-triazole (abtz) ligand has been employed, a unique cationic triazole–Ag(i) metal–organic nanotube {[Ag(μ₃-abtz)]·(NO₃)·(0.125H₂O)}_n (MONT-1) has been isolated under solvo-thermal conditions.

The dynamic response of a flexible indium based metal–organic framework to gas sorption

This work presents a flexible indium based MOF which exhibits a novel dynamic response to N₂, Ar and CO₂ sorption.

Two microporous metal–organic frameworks constructed from trinuclear cobalt(ii) and cadmium(ii) cluster subunits

This work presents two novel microporous metal–organic frameworks which are constructed from a tetracarboxylate ligand and trinuclear cobalt(ii) and cadmium(ii) cluster subunits.

The electrochemical properties, nitrogen adsorption, and photocatalytic activities of three 3D metal–organic frameworks bearing the rigid terphenyl tetracarboxylates ligands

Three new 3D complexes derived from the rigid terphenyl tetracarboxylates ligands with different transition metal ions have been successfully prepared. In addition, the title complexes exhibit different properties.

Anionic metal–organic framework hybrids: functionalization with lanthanide ions or cationic dyes and fluorescence sensing of small molecules

An anionic metal–organic framework, [HDMA]₂[Zn₂(BDC)₃(DMA)]·6DMF is modified by lanthanides and they exhibit selective adsorption ability to cationic dyes. RhB@1 has a rapidest response and realizes sensing acetone and aniline.

Topology-guided design of an anionic bor-network for photocatalytic [Ru(bpy)3]2+ encapsulation

An anionic metal–organic framework, PCN-99, has been synthesized through a topology-guided strategy; its underlying bor-net is realized by the use of a tetrahedral [In(COO)₄]⁻ node and a judiciously designed trigonal planar linker.

A microporous anionic metal–organic framework for a highly selective and sensitive electrochemical sensor of Cu2+ ions

We developed a microporous anionic metal–organic framework for a chemically modified electrode material. The modified electrode shows an excellent selectivity, high stability and sensitivity, wide linear range and lower detection limit for Cu²⁺ ion.

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.

A Zn-MOF constructed from electron-rich π-conjugated ligands with an interpenetrated graphene-like net as an efficient nitroaromatic sensor

A π-electron conjugated ligand has been employed in a Zn-MOF efficient fluorescent sensor for determining electron-deficient nitroaromatics.

An anionic zeolite-like metal–organic framework (AZMOF) with a Moravia network for organic dye absorption through cation-exchange

We have synthesized a new anionic zeolite-like metal–organic framework (AZMOF) with a twisted partially augmentedthenet, known as the “Moravia” net which is able to selectively adsorb organic cationic dyes (BR, RB, CV and MB) through cation-exchange.

A Naphthalenediimide-Based Metal-Organic Framework and Thin Film Exhibiting Photochromic and Electrochromic Properties

A multifunctional metal-organic framework, NBU-3, has been explored as a 2D three-connected network based on a naphthalenediimide-based ligand. The NBU-3 crystals display photochromic properties, and NBU-3 thin films on FTO substrates exhibit electrochromic properties. NBU-3 is the first example of MOF materials containing both photochromic and electrochromic properties, which can be desirable for thin film devices.

Advanced Cd(II) complexes as high efficiency co-sensitizers for enhanced dye-sensitized solar cell performance

This work reports on two new complexes with the general formula [Cd3(IBA)3(Cl)2(HCOO)(H2O)]n (1) and {[Cd1.5(IBA)3(H2O)6]·3.5H2O}n (2), which can be synthesized by the reaction of Cd(II) with rigid linear ligand 4-HIBA containing imidazolyl and carboxylate functional groups [4-HIBA = 4-(1H-imidazol-1-yl)benzoic acid]. Single-crystal X-ray diffraction analyses indicate that complex 1 is a 2D "wave-like" layer structure constructed from trinuclear units and complex 2 is just a mononuclear structure. Surprisingly, both complexes 1 and 2 appear as a 3D supramolecular network via intermolecular hydrogen bonding interactions. What's more, due to their strong UV-visible absorption, 1 and 2 can be employed as co-sensitizers in combination with N719 to enhance dye-sensitized solar cell (DSSC) performance. Both of them could overcome the deficiency of the ruthenium complex N719 absorption in the region of ultraviolet and blue-violet, and the charge collection efficiency is also improved when 1 and 2 are used as co-sensitizers, which are all in favor of enhancing the performance. The DSSC devices using co-sensitizers of 1/N719 and 2/N719 show an overall conversion efficiency of 8.27% and 7.73% with a short circuit current density of 17.48 mA cm(-2) and 17.39 mA cm(-2), and an open circuit voltage of 0.75 V and 0.74 V, respectively. The overall conversion efficiency is 27.23% and 18.92% higher than that of a device solely sensitized by N719 (6.50%). Consequently, the prepared complexes are high efficiency co-sensitizers for enhancing the performance of N719 sensitized solar cells.

Metal-Organic Frameworks as Chemical Sensors

Chemical sensing is of critical importance in today's society in a variety of applications from medicine to environmental pollution control, and from food safety monitoring to the detection of illicit substances and chemical weapons. Metal–organic frameworks (MOFs) have shown tremendous promise as a new class of chemical sensor materials that could be integrated into future devices. MOFs are microporous crystalline materials with infinite, periodic structures composed of organic ‘linkers’ connected to metal ‘nodes’. Their architectures can be fine-tuned by synthetic design for task-specific purposes: as chemical sensors, MOFs can be designed to interact with specific target analytes. Interest in MOFs as chemical sensors has grown significantly over the last decade, particularly given the increasing number of examples of luminescent lanthanide-based MOFs, and MOFs that display mechanochemical responses to external stimuli. In this chapter, we discuss some of the fundamental properties required to prepare MOFs for chemical sensing. We then present an extensive review of recent research in this area, showing how MOFs have been applied in a wide range of applications, including sensing of anions, cations, small organic molecules, biomolecules, as well as changes in physical conditions such as temperature and pH.

A Series of Multifunctional Metal-Organic Frameworks Showing Excellent Luminescent Sensing, Sensitization, and Adsorbent Abilities

A series of highly luminescent-active metal-organic frameworks (MOFs) 1-3 with hierarchical pores have been rationally constructed and fully characterized. The predesigned semi-rigid hexacarboxylate ligand hexa[4-(carboxyphenyl)oxamethyl]-3-oxapentane acid (H6 L) has been adapted with various space-directed N donors (i.e., 2,2'-bipyridine, 4,4'-di(1H-imidazol-1-yl)-1,1'-biphenyl, and 1,3,5-tri(1H-imidazol-1-yl)benzene) from a bidentate V-shape to a tridentate Y-shape. This family of multifunctional MOF materials represents a variety of potential applications in the following aspects: first, as luminescent sensors that show a fast and sensitive detection for pollutant CrO4 (2-) and Cr2 O7 (2-) ions in aqueous media; second, as adsorbents that can rapidly remove harmful organic dyes; third, as an antenna that can effectively sensitize visible-light-emitting Tb(3+) ions. These multifunctional MOF materials combine optical-sensing, adsorption, and sensitization properties, thus are very useful in many potential applications. Furthermore, these materials have proved to be reusable.