Cadmium Dicyanoaurates and Their Reaction with Ammonia

The synthesis and crystal structures of two anionic cadmium dicyanoaurate coordination polymers, [nBu4N]6[(Cd4Cl4)2(Au(CN)2)12][CdCl4] (TCCA) and [nBu4N]2[Cd(Au(CN)2)4], and their reaction with ammonia vapour is reported. TCCA and the isostructural [nBu4N]6[(Cd4Br4)2(Au(CN)2)12][CdBr4] form 3-D arrays with [Cd4X4]4+ (X=Cl, Br) cubane clusters linked from each octahedral Cd(II) centre by three bridging [Au(CN)2]- units. TCCA reacts with ammonia with concentrations of 1000 ppm or higher to give a product with a quantum yield of 0.88, while [nBu4N]2[Cd(Au(CN)2)4], which forms a 2-D anionic Cd[Au(CN)2]2 sheet structure with axially pendant [Au(CN)2]- units, reacts with concentrated ammonia vapour to generate Cd(NH3)2[Au(CN)2]2; this has a similar 2-D sheet structure but with axial NH3 units. Vibrational spectroscopy illustrated that the reaction of both Cd/[Au(CN)2]-based materials with ammonia proceeded by breaking Cd-NC bonds. For [nBu4N]2[Cd(Au(CN)2)4], this results in decomposition into [nBu4N][Au(CN)2] ⋅ 0.5H2O and Cd(NH3)2[Au(CN)2]2, while the reaction of ammonia with TCCA is reversible by heating the ammonia-bound sample above 110 °C. Cd[Au(CN)2]2 can be prepared by thermal removal of NH3 units from Cd(NH3)2[Au(CN)2]2.

Dual stimuli-responsive phosphorescence of a Pb(II) coordination polymer to acidic vapors and thermal treatment

We present a new intensely phosphorescent Pb(II) coordination polymer (1) containing a heteroatomic ligand. It has a quantum yield of 21.62% and a lifetime of 25.46 μs. The naked-eye solid-state photoluminescence of 1 significantly changes in response to acidic vapors and thermal treatment, indicating the coexistence of acidochromic and thermochromic luminescence.

Stimulus-Responsive Lanthanide MOF Materials Encapsulated with Viologen Derivatives: Characterization, Photophysical Properties and Sensing on Nitrophenols

Viologens (1,1'-disubstituted 4,4'-bipyridyls) possessing electron-deficient properties and redox activity are a class of suitable chromophores to assemble metal-organic hybrid photochromic materials. Thus, viologen-functionalized metal-organic frameworks (MOFs) have attracted much attention for their photochromic properties; however, the syntheses of lanthanide-viologen hybrid crystalline photochromic materials still face many challenges. For example, the structures and properties of the final products are difficult to predict and are limited by molecular configurations. In this work, host-guest composite-material Ln-NH₂ BDC-pbpy MOFs were constructed by encapsulating viologen derivative pbpyCl₂ . The pbpy²⁺ moieties are uniformly embed by their π-π conjugation in the pores of the 3D structure by electrostatic interactions. Due to the encapsulation of the chromophore pbpy²⁺ moieties, Ln-NH₂ BDC-pbpy MOFs have reversible photochromic properties: they can change color after irradiation and can return to the original color after being protected from light or heating. Interestingly, the fluorescence intensity decreases with illumination time and recovers in the dark. As a result, Ln-NH₂ BDC-pbpy MOFs show both photochromic and photomodulated fluorescence. Based on the outstanding fluorescence performance of the Ln-NH₂ BDC-pbpy MOFs, they also show a wonderful effect for detecting nitrophenols, especially TNP.

Simultaneous Occurrence of Vapochromism and Vapoluminescence in Formaldehyde-Responsive Amino-Functionalized Copper(I) Polymorphic Coordination Polymers

The use of vapor-responsive chromic materials in sensing applications for the detection of harmful volatile organic chemicals is rapidly expanding. Herein, four new amino-functionalized Cu(I) coordination polymers of [CuI(pyt-NH₂)]_n (1) and (2) and [CuSCN(pyt-NH₂)]_n (3) and (4) (where pyt-NH₂ = 2-amino-5-(4-pyridinyl)-1,3,4-thiadiazole) were successfully synthesized. Single-crystal X-ray diffraction analysis reveals that 1 and 2 are iodo-based polymorphs, while 3 and 4 are thiocyanato-based polymorphs. They possess densely diverse crystalline architectures decorated by uncoordinated amino groups as a binding site. Also, 1-4 show a variety of color and luminescence based on the structural diversity. Remarkably, 1 and 2 undergo the change of color and naked-eye solid-state luminescence in response to formaldehyde (FA) vapor, demonstrating simultaneous vapochromism and vapoluminescence. The chromic Cu(I) coordination polymers in this work present for the first time dual-mode vapochromism and vapoluminescence in a highly selective response to FA vapor. The responsive mechanism has been clarified by Fourier transform infrared spectroscopy (FT-IR), electrospray ionization mass spectrometry (ESI-MS), ¹H nuclear magnetic resonance (NMR), powder X-ray diffraction (PXRD), and luminescence lifetime measurements, which reveal carbinolamine formation via the specific reaction between FA and the active amino groups of coordinated pyt-NH₂. The carbinolamine formation can trigger the structural transformation of 1 and 2, leading to the concurrently selective vapochromism and vapoluminescence induced by FA vapor.

Applications of Viologens in Organic and Inorganic Discoloration Materials

Viologen derived from 4,4'-bipyridine has attracted much attention because of its color changing properties with electron transfer, unique redox stability and structural diversity. These characteristics have led to its successful use in various applications, in particular in color-changing materials. In the past few years, researchers have been working on the syntheses of viologen-based color-changing functional materials, and such materials have been widely used in many fields. In photochromic materials, it is used as anti-counterfeiting material; in thermochromic, it is used as memory storage material, and in electrochromic, it is used as a battery material. This Review discusses the progress of viologen in organic and inorganic discoloration materials in recent years. The syntheses of viologen and its derivatives are summarized, and its application in the field of discoloration materials is introduced.

Metal-organic framework bearing new viologen ligand for ammonia and Cr2O7 2- sensing

Three anionic metal-organic frameworks (MOFs) {[Zn₃(BTEC)₂(H₂O)(4-BCBPY)]·(H₂O)} _n (1-3) (BTEC^4- = 1,2,4,5-benzenetetracarboxylic acid anion, 4-BCBPY²⁺ = 1,1'-bis(4-cyanobenzyl)-4,4'-bipyridinium dication) were synthesized in the reaction of 1,2,4,5-benzenetetracarboxylic acid with different metal salts such as ZnNO₃, ZnCl₂, and ZnSO₄, under solvothermal conditions in the presence of 1,1'-bis(4-cyanobenzyl)-4,4'-bipyridinium chloride. Single crystal X-ray diffraction analysis shows that compounds 1, 2 and 3 have MOF structures based on binuclear metal building units, which are connected by two protonated BTEC^4- ligands and three zinc ions, and the viologen cation 4-BCBPY²⁺ is located in the channel to achieve charge balance. Compounds 1, 2 and 3 have good photosensitivity, respond to sunlight, UV light and blue ray, and turn blue. The D-A distance and π-π stacking distance of the discolored samples (1P, 2P and 3P) changed. In addition, the three compounds showed visible color changes to ammonia vapor, rapidly changing from white to blue. At the same time, the three compounds exhibited fluorescence quenching to ammonia vapor and Cr₂O₇ ^2-. It is further proved that compounds 1, 2 and 3 are fluorescent sensors with a low detection limit (for Cr₂O₇ ^2-: 10^-5 M) and high sensitivity for ammonia vapor and Cr₂O₇ ^2-. It was found that photochromic behavior, ammonia sensing properties can be tuned by the nature of metal salts.

Porous Hexacyanometallate(III) Complexes as Catalysts in the Ring-Opening Copolymerization of CO2 and Propylene Oxide

In this work, six porous hexacyanometallate complexes (Ni3[Co(CN)6]2, Co3[Co(CN)6]2, Fe3[Co(CN)6]2, Ni3[Fe(CN)6]2, Co3[Fe(CN)6]2, Fe4[Fe(CN)6]2) were synthesized by a complexing agent assisted coprecipitation method and thoroughly characterized via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), in situ high-temperature X-ray diffraction (HT-XRD), elemental analysis (EA), X-ray fluorescence (XRF), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 physisorption, and gas–solid phase titration with NH3. The thermal stability, chemical composition, pore size and volume, crystallite size and density of surface acid sites were strongly sensitive to both the transition metal and the cyanometallate anion employed. On that basis, transition metal hexacyanometallates must be perceived as an adaptable class of zeolite-like microporous materials. The catalytic properties of these compounds were tested by copolymerization of propylene oxide and CO2, a green route to obtain biodegradable aliphatic polycarbonates. All compounds under study showed moderate activity in the target reaction. The obtained copolymers were characterized by modest CO2 content (carbonate units ranging from 16 to 33%), random structure (RPEC ≈ 70%), and moderate molecular weight (Mw = 6000–85,400 g/mol) with broad dispersity values (ĐM = 4.1–15.8).

A Series of Polyoxometalate-Viologen Photochromic Materials for UV Probing, Amine Detecting and Inkless and Erasable Printing

In this work, by using two kinds of viologen ligands three POM-based Compounds were obtained under hydrothermal conditions, namely [Ag^I (bmypd)_0.5 (β-Mo₈ O₂₆ )_0.5 ] (1) (bmypd ⋅ 2Cl=1,1'-[Biphenyl-4,4'-bis(methylene)]bis(4,4'-bipyridyinium)dichloride), [Ag^I ₂ (bypy)₄ (HSiW₁₂ O₄₀ )₂ ] ⋅ 14H₂ O (2) and [Ag^I (bypy)(γ-Mo₈ O₂₆ )_0.5 ] (3) (bypy⋅Cl=1-Benzyl-4,4'-bipyridyinium chloride). The structures were characterized by Fourier transform infrared spectroscopy (FT-IR), Powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS) and single crystal X-ray diffraction. Compounds 1-3 show excellent photochromic ability with fast photoresponse under the irradiation of ultraviolet light with different degrees of color changes. So compounds 1-3 can be used as visible ultraviolet detectors. Compounds 1-3 also possess photoluminescence properties with fast and excellent fluorescence quenching effect. Compounds 1-3 also can be used as inkless and erasable printing materials with suspensions of 1-3 applied to filter paper. Compounds 1-3 can also produce color changes in amine vapor environment, especially in an NH₃ atmosphere. Compounds 1-3 can be used as organic amine detectors.

An electron-deficient naphthalene diimide-based metal-organic framework for detecting electron-rich molecules through photo-/chemo-induced chromism

A novel naphthalene diimide-based metal-organic framework (MOF) {[Zn(3-DPMNI)_0.5(NDC)]·3DMF} (1@DMF), (H₂NDC = 2,6-naphthalenedicarboxylic acid, DPMNI = N,N'-bis(3-pyridylmethyl)-1,4,5,8-naphthalene diimide, DMF = N,N'-dimethylformamide), has been synthesized, which shows a 3D pillar-layer architecture built of carboxylate layers and naphthalene diimide pillars. The compound exhibits outstanding photochromic performance due to photoinduced electron transfer (ET) between the electron-rich guest molecules and electron-deficient host framework (host-guest ET). Of note, the host framework of 1 cannot show a macroscopic color change owing to the absence of the ET pathway. Nevertheless, it exhibits discriminative photochromic behavior in the presence of electron-rich solvents, which is mainly attributed to different electron-donating abilities of guest solvents and distinct interfacial contacts of electron donors/acceptors. Furthermore, the MOF can also show discriminative ET chemochromic response to different sizes and shapes of organic amines, which can be potentially used for the visual detection of electron-rich organic amines, especially n-butylamine (n-BUA).

Magnetic Switching in Vapochromic Oxalato-Bridged 2D Copper(II)-Pyrazole Compounds for Biogenic Amine Sensing

A new two-dimensional (2D) coordination polymer of the formula {Cu(ox)(4-Hmpz)·1/3H2O}n (1) (ox = oxalate and 4-Hmpz = 4-methyl-1H-pyrazole) has been prepared, and its structure has been determined by single-crystal X-ray diffraction. It consists of corrugated oxalato-bridged copper(II) neutral layers featuring two alternating bridging modes of the oxalate group within each layer, the symmetric bis-bidentate (μ-κ2O1,O2:κ2O2′,O1′) and the asymmetric bis(bidentate/monodentate) (μ4-κO1:κ2O1,O2:κO2′:κ2O2′,O1′) coordination modes. The three crystallographically independent six-coordinate copper(II) ions that occur in 1 have tetragonally elongated surroundings with three oxygen atoms from two oxalate ligands, a methylpyrazole-nitrogen defining the equatorial plane, and two other oxalate-oxygen atoms occupying the axial positions. The monodentate 4-Hmpz ligands alternatively extrude above and below each oxalate-bridged copper(II) layer, and the water molecules of crystallization are located between the layers. Compound 1 exhibits a fast and selective adsorption of methylamine vapors to afford the adsorbate of formula {Cu(ox)(4-Hmpz)·3MeNH2·1/3H2O}n (2), which is accompanied by a concomitant color change from cyan to deep blue. Compound 2 transforms into {Cu(ox)(4-Hmpz)·MeNH2·1/3H2O}n (3) under vacuum for three hours. The cryomagnetic study of 1–3 revealed a unique switching from strong (1) to weak (2 and 3) antiferromagnetic interactions. The external control of the optical and magnetic properties along this series of compounds might make them suitable candidates for switching optical and magnetic devices for chemical sensing.

Chromic and Fluorescence-Responsive Metal-Organic Frameworks Afforded by N-Amination Modification

Sensory materials that show color and/or fluorescence changes in response to specific gases or vapors have important applications in many fields. Here, we report the postsynthetic preparation of novel sensory metal-organic frameworks (MOFs) and their multiple responsive properties. Through postsynthetic N-amination, the 2,2'-bipyridyl spacers in a Zr(IV) MOF are partially transformed into N-aminobipyridinium. The new MOF (Zr-bpy-A) shows chromic behavior toward ammonia and amines because the electron-deficient pyridinium groups form charge-transfer complexes with amino moieties. It also shows a unique chromic response to formaldehyde owing to the Schiff-base condensation with the N-amino groups. Furthermore, the N-amino group can be used to graft different polycyclic aromatic hydrocarbons, which endow the MOF with strong fluorescence of variable colors and afford a high-contrast fluorescence response to ammonia/amines and formaldehyde associated with the chromic response. The presence of the unquaternized bipyridyl group also leads to a fluorescence response to HCl. The multiple responsive behaviors hold appeal for applications in sensing, switching, and antifake marking, which are illustrated with a test paper and writing ink.

Distinct and Selective Amine- and Anion-Responsive Behaviors of an Electron-Deficient and Anion-Exchangeable Metal-Organic Framework

Smart materials that respond to chemical stimuli with color or luminescence changes are highly desirable for daily-life and high-tech applications. Here, we report a novel porous metal-organic framework (MOF) that shows multiple, selective, and discriminative responsive properties owing to the combination of different functional ingredients [tripyridinium chromogen, Eu(III) luminophore, cationic framework, and special porous structure]. The MOF contains two interpenetrated three-dimensional cationic coordination networks built of a tetrahedral [Eu₄(μ₃-OH)₄] cluster and a tripyridinium-tricarboxylate zwitterionic linker. It shows reversible and discriminative chromic response to aliphatic amines and aniline through different host-guest interactions between electron-deficient pyridinium and electron-rich amines. The size- and shape-selective response to aliphatic amines is ascribed to the radical formation through host-guest electron transfer, whereas the response to aniline is ascribed to the formation of sandwich-type acceptor-donor-acceptor complexes. The MOF is capable of reversible anion exchange with various anions and shows selective and discriminative ionochromic response to iodide, bromide, and thiocyanate, which is attributed to charge-transfer complexation. The above chromic behaviors are accompanied by efficient quenching of Eu(III) photoluminescence. The MOF represents a multi-stimuli dual-output responsive system. It can be used for discrimination and identification of anions and amines. The potential use in invisible printing, reusable sensory films, and optical switches was demonstrated by the ink and the membrane made of the MOF and organic polymers.

Pd/APN-Mn(BTC) as novel, highly efficient, and recyclable catalyst for Suzuki–Miyaura cross coupling reaction

A novel, heterogeneous, and bifunctional metal organic framework containing palladium and manganese, Pd/APN-Mn(BTC), has been prepared and completely characterized using FTIR, XRD, SEM-EDS, N2 adsorption–desorption, TG-DTG, NH3-TPD, and ICP analytical techniques. The APN-Mn(BTC) framework has been shown to be a useful platform for the stabilization and support of palladium nanoparticles (Pd NPs). Very effective catalytic activity has been exhibited by the highly dispersed Pd particles, Pd-NPs/APN-Mn(BTC), in the Suzuki–Miyaura cross-coupling reaction with reasonable to excellent reaction yields under mild conditions in H2O–ethanol solvent.

Research on Treatment of Oily Sludge from the Tank Bottom by Ball Milling Combined with Ozone-Catalyzed Oxidation

Difficult separation of oil-solid phase and high fine content of the recovered oil were two problems in the treatment of oily sludge from the tank bottom by the hot water-based extraction process. To solve the problems, one technology with "ball milling + ozone-catalyzed oxidation" as the core was studied, and the process parameters of ball milling and ozone-catalyzed oxidation were respectively optimized. After ball milling treatment, the oil content of dry oily sludge decreased from 33.9 to 10.2%. Then, an ozone catalytic oxidation treatment technology with aluminum ore as the catalyst was developed to further treat this stubborn oily sludge. Under the optimal conditions, the oil content of oily sludge could be further reduced to 0.28%, which met the treatment and disposal requirements stipulated in GB4284-2018. For further research on the contribution of the catalyst to the ozone catalytic oxidation system, the reaction activation energy and reaction rates of ozone oxidation and ozone catalytic oxidation were compared from the perspective of kinetics. The results showed that, with the catalyst addition, the reaction rate constants increased about three times and the reaction activation energy reduced 82.26%, which showed the effectiveness of the catalyst on the kinetics quantitatively. The combined process with "ball milling + ozone-catalyzed oxidation" as the core can solve the two problems in the treatment of oily sludge from the tank bottom by hot water-based extraction and provides a reference for the harmless and resourceful treatment of oily sludge from the tank bottom.

A Zr-cluster based thermostable, self-healing and adaptive metallogel with chromogenic properties responds to multiple stimuli with reversible radical interaction

A Zr-cluster based metallogel is synthesized via an unusual one-pot solvothermal method. The resulting metallogel is robust, adaptive, self-healing, highly thermostable and conductive. Moreover, the metallogel exhibits reversible stimuli-responsive properties. The gel could respond to at least four kinds of stimuli such as light, aliphatic amines, electricity and metals with color and fluorescence tunability. Importantly, the metallogel with electrochromic properties could be used as soft electrochromic devices for smart windows and electro display boards, and metalchromism provides a practical way for coating corrosion monitoring of metal materials.

Polyoxometalate–viologen photochromic hybrids for rapid solar ultraviolet light detection, photoluminescence-based UV probing and inkless and erasable printing

Polyoxometalate–viologen photochromic hybrids showed efficient and fast low intensity ultraviolet light detection, potential fluorescence based UV probing and inkless and erasable printing.

Selective chemochromic and chemically-induced photochromic response of a metal–organic framework

The MOF provides unique confined space furnished with electron acceptor sites, and exposure to amines/alcohols causes specific and size-selective direct/UV-assisted color change owing to spontaneous/photoinduced electron transfer.

From IR to x-rays: gaining molecular level insights on metal-organic frameworks through spectroscopy

This topical review focuses on the application of several types of spectroscopy methods to a class of solid state materials called metal organic frameworks (MOFs). MOFs are self-assembled, porous crystalline materials composed of metal cluster nodes linked through coordination bonds with organic or organometallic molecular constituents. Their unique host-guest properties make them attractive for many adsorption-based applications such as gas storage and separation, catalysis, sensing and others. While much research focuses on the development and application of these materials, fundamental studies of MOF properties and molecular level host-guest interactions behind their functionality have become a significant research direction on its own. Spectroscopy methods are now ubiquitous tools in this pursuit. This review focuses on the application of three classes of spectroscopy methods to MOF materials: vibrational, optical electronic and x-ray spectroscopies. Following brief introductions to each method that include pertinent theory and experimental considerations, we present a broad overview of the types of MOF systems that have been studied, with specific examples and important new molecular level insights highlighted along the way. The current status of spectroscopic studies of MOFs is presented at the end along with some perspectives on the future directions in this area of research.

Guest-Selective Recognition in a Flexible Bipyridinium-Based Framework in a Reversible Crystal-to-Crystal Fashion

A flexible bipyridinium-linker-based porous host framework with electron-accepting pore surface, namely, [Zn₂ (L)(pmc)_1.5 ]⋅12 H₂ O (1; L⋅Cl₂ =1,1'-[1,4-phenylene-bis(methylene)]bis(4,4'-bipyridinium) dichloride, H₄ pmc=pyromellitic acid) exhibits recognition of phenol and aromatic amine guests based on adsorbent-adsorbate charge-transfer interactions. Significantly, the resultant guest-encapsulated complexes 1@Guests can all be characterized by single-crystal X-ray diffraction. The host framework undergoes a reversible single crystal-to-single crystal transformation in response to the inclusion of different guests with flexible torsional motions of the hexagonal ring and the trapezoid-shaped bipyridinium groups. Such recognition can be visibly monitored and detected by obvious color changes. The host framework could also be recovered, and this suggested that guest sorption/desorption is reversible and that the host framework could be reused in potential applications. This work may provide an effective way to develop porous materials with special emphasis on applications involving guest recognition.

A vapochromic strategy for ammonia sensing based on a bipyridinium constructed porous framework

A vapochromic strategy has been developed for ammonia sensing through the competitive complexation of ammonia and an enhanced charge transfer effect.

Vapour-driven crystal-to-crystal transformation showing an interlocking switch of the coordination polymer chains between 1D and 3D

A rare crystal-to-crystal transformation occurs between 1D coordination polymer chains and 3D mechanically interlocked structures via reversible opening and closing of the homogeneous chains without any change in the coordination mode and composition.

Extremely stable europium-organic framework for luminescent sensing of Cr2O72− and Fe3+ in aqueous systems

A novel Eu-MOF which is extremely stable in an aqueous system over a wide pH range is reported as a dual functional Cr₂O₇²⁻ and Fe³⁺ sensor in aqueous environments.

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.

Postsynthetic N-methylation making a metal–organic framework responsive to alkylamines

The postsynthetically created electron-deficient bipyridinium moieties in a Zr-MOF provide charge-transfer sites for selectively recognizing and capturing alkylamines with fast and reversible vapochromism and luminescence quenching.

Anion-controlled photochromism of two bipyridinium-based coordination polymers and nondestructive luminescence readout

The first Zn-based coordination polymer constructed with a bipyridinium-functionalized m-benzenedicarboxyl ligand has been synthesized, which can show dual luminescence responses to light in different spectral regions to render nondestructive luminescence readout.

Photoluminescent Metal-Organic Frameworks for Gas Sensing

Luminescence of porous coordination polymers (PCPs) or metal-organic frameworks (MOFs) is sensitive to the type and concentration of chemical species in the surrounding environment, because these materials combine the advantages of the highly regular porous structures and various luminescence mechanisms, as well as diversified host-guest interactions. In the past few years, luminescent MOFs have attracted more and more attention for chemical sensing of gas-phase analytes, including common gases and vapors of solids/liquids. While liquid-phase and gas-phase luminescence sensing by MOFs share similar mechanisms such as host-guest electron and/or energy transfer, exiplex formation, and guest-perturbing of excited-state energy level and radiation pathways, via various types of host-guest interactions, gas-phase sensing has its unique advantages and challenges, such as easy utilization of encapsulated guest luminophores and difficulty for accurate measurement of the intensity change. This review summarizes recent progresses by using luminescent MOFs as reusable sensing materials for detection of gases and vapors of solids/liquids especially for O₂, highlighting various strategies for improving the sensitivity, selectivity, stability, and accuracy, reducing the materials cost, and developing related devices.

Halogen-bridged metal–organic frameworks constructed from bipyridinium-based ligand: structures, photochromism and non-destructive readout luminescence switching

Halogen-bridged photochromic metal–organic frameworks have been reported, and one can exhibit photomodulated luminescence featuring a non-destructive readout capability.

A Cu(ii) MOF with a flexible bifunctionalised terpyridine as an efficient catalyst for the single-pot hydrocarboxylation of cyclohexane to carboxylic acid in water/ionic liquid medium

A bifunctionalised terpyridine based Cu(ii) MOF for efficient hydrocarboxylation of cyclohexane to cyclohexanecarboxylic acid in an ionic liquid medium.

Functional metal–bipyridinium frameworks: self-assembly and applications

Metal–organic frameworks as newly emerged materials have experienced rapid development in the last few years. This perspective highlights recent progress of study on the self-assembly of metal–bipyridinium frameworks and their intriguing properties for various applications.