Luminescence Nanothermometry: Investigating Thermal Memory in UiO-66-NH Nanocrystals.

Metal-organic frameworks (MOFs), a diverse and rapidly expanding class of crystalline materials, present many opportunities for various applications. Within this class, the amino-functionalized Zr-MOF, namely, UiO-66-NH, stands out due to its distinctive chemical and physical properties. In this study, we report on the new unique property where UiO-66-NH nanocrystals exhibited enhanced fluorescence upon heating, which was persistently maintained postcooling.

Controlled Growth of Highly Defected Zirconium-Metal-Organic Frameworks via a Reaction-Diffusion System for Water Remediation.

The relentless growth of metal-organic framework (MOF) chemistry is paralleled by the persistent urge to control the MOFs physical and chemical properties. While this control is mostly achieved by solvothermal syntheses, room temperature procedures stand out as more convenient and sustainable pathways for the production of MOF materials. Herein, a novel approach to control the crystal size and defect numbers of a dihydroxy-functionalized zirconium-based metal-organic framework (UiO-66(OH)) at room temperature is reported.

Effect of amino functional groups on the surface properties and Lewis's acid base parameters of UiO-66(NH) by inverse gas chromatography.

Amino-functionalized metal organic frameworks (MOFs) have attracted much attention for various applications such as carbon dioxide capture, water remediation and catalysis. The focus of this study is to determine the surface and Lewis's acid-base properties of UiO-66(NH) crystals by the inverse gas chromatography (IGC) technique at infinite dilution. The latter was applied to evaluate the dispersive component of the surface energy by using thermal model and several molecular models.

Electrospun Metal-Organic Framework-Fabric Nanocomposites as Efficient Bactericides.

In this work, we utilized electrospinning to develop advanced composite membranes of polyvinyl chloride (PVC) loaded with postmetalated metal-organic frameworks (MOFs), specifically UiO-66(COOH)-Ag and ZIF-8-Ag. This innovative technique led to the creation of highly stable PVC/MOFs-Ag membrane composites, which were thoroughly characterized using various analytical techniques, including scanning electron microscopy, powder X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, porosity analysis, and water contact angle measurement. The results verified the successful integration of MOF crystals within the nanofibrous PVC membranes.

Selective Photocatalytic Dehydrogenation of Formic Acid by an -Restructured Copper-Postmetalated Metal-Organic Framework under Visible Light.

Formic acid is considered as one of the most promising liquid organic hydrogen carriers. Its catalytic dehydrogenation process generally suffers from low activity, low reaction selectivity, low stability of the catalysts, and/or the use of noble-metal-based catalysts. Herein we report a highly selective, efficient, and noble-metal-free photocatalyst for the dehydrogenation of formic acid.

Surface thermodynamics and Lewis acid-base properties of metal-organic framework Crystals by Inverse gas chromatography at infinite dilution.

In this study, the surface thermodynamic properties and more particularly, the dispersive component γ of the surface energy of crystals of a Zr-based MOF, UiO-66 (ZrO(OH)(BDC); BDC = benzene 1,4-dicarboxylic acid), the specific interactions, and their acid-base constants were determined by using different molecular models and inverse gas chromatography methods. The determination of γ of the UiO-66 surface was obtained by using several models such as Dorris-Gray and those based on the Fowkes relation by applying the various molecular models giving the surface areas of n-alkanes and polar organic molecules. Six models were used: Kiselev, spherical, geometric, Van der Waals, Redlich-Kwong, and cylindrical models.

Metallated Isoindigo-Porphyrin Covalent Organic Framework Photocatalyst with a Narrow Band Gap for Efficient CO Conversion.

Photocatalytic CO reduction into formate (HCOO) has been widely studied with semiconductor and molecule-based systems, but it is rarely investigated with covalent organic frameworks (COFs). Herein, we report a novel donor-acceptor COF named composed of isoindigo and metallated porphyrin subunits that exhibits high catalytic efficiency (∼50 μmol formate g h) at low-power visible-light irradiation and in the absence of rare metal cocatalysts. Density functional theory calculations and experimental diffuse-reflectance measurements are used to explain the origin of catalytic efficiency and the particularly low band gap (0.

Tuning the structural properties of cadmium-aluminum layered double hydroxide for enhanced photocatalytic dye degradation.

The distinctive layered structure, chemical stability and tunability of layered double hydroxides (LDHs) have led to extensive investigations in various areas of photocatalysis, including photocatalytic water splitting, carbon dioxide photoreduction, and degradation of organic pollutants. Here, a series of visible light active cadmium-aluminum layered double hydroxides (CdAl LDHs) with various Cd : Al ratios is synthesized the reaction-diffusion framework (RDF) leading thereby to a hierarchal spherical structure of the LDH. The aim of this study is to develop an optimal CdAl LDH photocatalyst that is activated by solar light irradiation and tested for methylene blue (MB) degradation.

Two-Dimensional Metal-Organic Framework Nanosheets as a Dual Ratiometric and Turn-off Luminescent Probe.

Current research on metal-organic framework (MOF) luminescent sensing probes focuses on the design of three-dimensional bulk-sized MOFs that in return limits their up-close interactions with targeted guest molecules. In this work, we report a two-dimensional (2D) copper-based metal-organic framework, namely, AUBM-6, synthesized via solvothermal method from isonicotinic acid linker and copper(II) ion. The resulting 2D-layered MOF crystals were highly fluorescent in their exfoliated form and, therefore, explored for detecting several solvents, where a ratiometric selectivity was shown toward acetone.

Liesegang Banding for Controlled Size and Growth of Zeolitic-Imidazolate Frameworks.

Here, the formation of periodic precipitation (Liesegang bands) from hybrid (organic-inorganic) components is reported, namely ZIF-8, ZIF-67, and their mixed metal derivatives. The spacing and width laws that characterize the Liesegang system are determined and the resulting pattern is exploited to crystal engineer various sizes and doping of the ZIF material. Several key parameters that govern the crystallization process of ZIF-8 are investigated in each band and the growth of the particles in each band is found to follow an Ostwald ripening mechanism.

Metal-Organic Framework Photocatalyst Incorporating Bis(4'-(4-carboxyphenyl)-terpyridine)ruthenium(II) for Visible-Light-Driven Carbon Dioxide Reduction.

In this study, we report the successful incorporation of the photoactive bis(4'-(4-carboxyphenyl)-terpyridine)ruthenium(II) (Ru(cptpy)) strut into a robust metal-organic framework (MOF), AUBM-4. The single crystal X-ray analysis revealed the formation of a new one-dimensional structure of Ru(cptpy) complexes linked together by Zr atoms that are eight coordinated with O atoms. The chemically stable MOF structure was employed as an efficient photocatalyst for carbon dioxide conversion to formate under visible light irradiation.

Enhancing porphyrin photostability when locked in metal-organic frameworks.

Porphyrins have been widely used in many optical devices given their unique photochemical properties. Their poor photostability has, however, limited their wide applications in bioimaging and biosensing schemes. Herein, we report the remarkable photostability enhancement of the porphyrin, carboxyphenyl porphyrin (TCPP-H2) when locked in a zirconium based metal-organic framework (MOF-525).

Crystal Growth of ZIF-8, ZIF-67, and Their Mixed-Metal Derivatives.

A facile method to produce zeolitic imidazolate frameworks (ZIF-8, ZIF-67, and solid-solution ZIFs (mixed Co and Zn)) is reported. ZIF crystals are produced via a reaction-diffusion framework (RDF) by diffusing an outer solution at a relatively high concentration of the 2-methyl imidazole linker (HmIm) into an agar gel matrix containing the metal ions (zinc(II) and/or cobalt(II)) at room temperature. Accordingly, a propagating supersaturation wave, initiated at the interface between the outer solution and the gel matrix, leads to a precipitation front with a gradient of crystal sizes ranging between 100 nm and 55 μm along the reaction tube.

A highly stable indium based metal organic framework for efficient arsenic removal from water.

A new porous indium metal organic framework namely (AUBM-1) was successfully synthesized via a solvothermal reaction of pyromellitic acid and indium chloride. Single crystal X-ray analysis revealed the formation of a 3D framework with a pts topology. The resulting MOF structure showed high chemical stability at different pH values.

Postmetalated Zirconium Metal Organic Frameworks as a Highly Potent Bactericide.

Metal-organic frameworks (MOFs) have emerged as an important class of hybrid organic-inorganic materials. One of the reasons they have gained remarkable attention is attributed to the possibility of altering them by postsynthetic modification, thereby providing access to new and novel advanced materials. MOFs have been applied in catalysis, gas storage, gas separation, chemical sensing, and drug delivery.

Visible and Near-Infrared Photothermal Catalyzed Hydrogenation of Gaseous CO over Nanostructured Pd@NbO.

The reverse water gas shift (RWGS) reaction driven by NbO nanorod-supported Pd nanocrystals without external heating using visible and near infrared (NIR) light is demonstrated. By measuring the dependence of the RWGS reaction rates on the intensity and spectral power distribution of filtered light incident onto the nanostructured Pd@NbO catalyst, it is determined that the RWGS reaction is activated photothermally. That is the RWGS reaction is initiated by heat generated from thermalization of charge carriers in the Pd nanocrystals that are excited by interband and intraband absorption of visible and NIR light.

Encapsulation of curcumin in cyclodextrin-metal organic frameworks: Dissociation of loaded CD-MOFs enhances stability of curcumin.

Curcumin has been successfully encapsulated in cyclodextrin-metal organic frameworks (CD-MOFs) without altering their crystallinity. The interaction between curcumin and CD-MOFs is strong through hydrogen bond type interaction between the OH group of cyclodextrin of CD-MOFs and the phenolic hydroxyl group of the curcumin. Interestingly, dissolving the curcumin loaded CD-MOFs crystals in water results in formation of a unique complex between curcumin, γCD and potassium cations.

Cadmium-Aluminum Layered Double Hydroxide Microspheres for Photocatalytic CO2 Reduction.

We report the synthesis of cadmium-aluminum layered double hydroxide (CdAl LDH) using the reaction-diffusion framework. As the hydroxide anions diffuse into an agar gel matrix containing the mixture of aluminum and cadmium salts at a given ratio, they react to give the LDH. The LDH self-assembles inside the pores of the gel matrix into a unique spherical-porous shaped microstructure.

New hydrogen-evolution heteronanostructured photocatalysts: Pt-Nb3 O7 (OH) and Cu-Nb3 O7 (OH).

Nanorods of triniobium hydroxide heptaoxide, Nb3 O7 (OH), were synthesized by means of a hydrothermal method. Subsequently, Pt and CuO nanoparticles were introduced on the surface of Nb3 O7 (OH) nanorods by a microwave-assisted solvothermal nucleation and growth technique. The resulting Pt- and CuO-decorated Nb3 O7 (OH) nanorods demonstrated uniform particle dispersion and were fully characterized by X-ray diffraction, electron microscopy, and spectroscopic analysis.

Large-pore apertures in a series of metal-organic frameworks.

We report a strategy to expand the pore aperture of metal-organic frameworks (MOFs) into a previously unattained size regime (>32 angstroms). Specifically, the systematic expansion of a well-known MOF structure, MOF-74, from its original link of one phenylene ring (I) to two, three, four, five, six, seven, nine, and eleven (II to XI, respectively), afforded an isoreticular series of MOF-74 structures (termed IRMOF-74-I to XI) with pore apertures ranging from 14 to 98 angstroms. All members of this series have noninterpenetrating structures and exhibit robust architectures, as evidenced by their permanent porosity and high thermal stability (up to 300°C).

Metal-organic frameworks incorporating copper-complexed rotaxanes.

[Image: see text] A copper coordinated [2]pseudorotaxanate which reacts with zinc nitrate to form an extended structure, consisting of three-fold interpenetrated networks, retains most of its solution-state chemistry including its ability to undergo electronic switching of some of the copper(I) ions under redox control.

Electrostatic barriers in rotaxanes and pseudorotaxanes.

The ability to control the kinetic barriers governing the relative motions of the components in mechanically interlocked molecules is important for future applications of these compounds in molecular electronic devices. In this Full Paper, we demonstrate that bipyridinium (BIPY(2+)) dications fulfill the role as effective electrostatic barriers for controlling the shuttling and threading behavior for rotaxanes and pseudorotaxanes in aqueous environments. A degenerate [2]rotaxane, composed of two 1,5-dioxynaphthalene (DNP) units flanking a central BIPY(2+) unit in the dumbbell component and encircled by the cyclobis(paraquat-p-phenylene) (CBPQT(4+)) tetracationic cyclophane, has been synthesized employing a threading-followed-by-stoppering approach.

Acid-base actuation of [c2]daisy chains.

A versatile synthetic strategy, which was conceived and employed to prepare doubly threaded, bistable [c2]daisy chain compounds, is described. Propargyl and 1-pentenyl groups have been grafted onto the stoppers of [c2]daisy chain molecules obtained using a template-directed synthetic protocol. Such [c2]daisy chain molecules undergo reversible extension and contraction upon treatment with acid and base, respectively.