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A highly stable and luminescent metal-organic framework (LMOF) with layered structure, namely, C6H4N5OZn (1) has been successfully achieved and fully characterized by single crystal X-ray diffraction, powder X-ray diffractions, fluorescence titration and thermogravimetry. This blue-light emitting compound 1 exhibit outstanding stability and can detect Fe3+ and Cu2+ in water specifically, presenting potential application in the field of fluorescent probe technology. Fluorescence titration experiments indicate that the detection of Fe3+ ions by 1 is more significant than that of Cu2+ ions in terms of Ksv value. Furthermore, guest-assisted exfoliation of layered MOF 1 is efficiently carried out through ether O H hydrogen bond or π···π interactions between the layered host structure and intercalated guest molecules (4,4′-oxybisbenzoic acid and triphenylamine). Tyndal scattering was observed in the suspensions of obtained MOF nanosheets. This study shows that the compound 1 with unique metal ion sensing properties can be applied as a probe material in water pollution treatment field, but also opens up the opportunity for synthesizing luminescent MONs through the “bottom-up” guest intercalation methodology.

The compound [(CH3)2CH-C3H17N][CoBr4] (1) based on quinuclidine derivatives was achieved by the solution synthetic method and characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray structural analysis and dielectric measurement, respectively. Variable-temperature single-crystal X-ray diffraction suggested that the compound underwent the phase transition from the space group C2/c to Cc. The polarization curve was measured using the Sawyer-Tower circuit. The structural phase transitions of 1 was ascribed to the distortion of a [(CH3)2CH-C3H17N]2+ cation from this inorganic–organic hybrid material [(CH3)2CH-C3H17N][CoBr4]. The strong change in dielectric anomalies makes compound 1 a suitable candidate for promising switchable dielectric materials. This work represents a feasible strategy thought for the targeted harvesting of low temperature ferroelectrics.

Organic-inorganic ABX3 (A, B = cations, X = anion) hybrids with perovskite structure have recently attracted tremendous interest due to their structural tunability and rich functional properties, such as ferroelectricity. However, ABX3 hybrid ferroelectrics with other structures have rarely been reported. Here, we successfully designed an ABX3 hybrid ferroelectric [(CH3)3NCH2F]ZnCl3 with a spontaneous polarization of 4.8 μC/cm2 by the molecular modification of [(CH3)4N]ZnCl3 through hydrogen/halogen substitution. It is the first zinc halide ABX3 ferroelectric, which contains one-dimensional [ZnCl3]-n chains of corner-sharing ZnCl4 tetrahedra, distinct from the anionic framework of corner-sharing or face-sharing BX6 octahedra in the ABX3 perovskites. From zero dimension to one dimension, the high symmetry of ZnCl4 tetrahedra is broken, and all of them align along one direction to form a polar [ZnCl3]-n chain, beneficial to the generation of ferroelectricity. This finding provides an efficient polar anionic framework for enriching the family of hybrid ferroelectrics by assembling with various cations and should inspire further exploration of new classes of organic-inorganic ABX3 ferroelectrics.

Crystalline coordination architectures with coordinatively unsaturated metal sites are of great importance for their attractive properties. Tunable side chains of the 4-formylimidazole here were employed for directing the subcomponent self-assembly of (CuIIN4)2(CuII)2 (1), {(CuIIN4)(CuII)2}n (2), {L(CuII)2}n (3) under the same solvothermal condition, giving the structural diversity. The unique square-planar CuII/NiIIN4 units with open metal sites can not only be in situ embedded in 1 and 2, but also be successfully immobilized in {(NiIIN4)2(CuICN)9}n (4) and {(CuIIN4)2(CuICN)9}n (5), through the metalloligand strategy. Enzyme-like substrate-specific activity was observed by employing 5 as a heterogeneous catalyst, which exhibit increased activity and high selectivity towards the catalytic oxidation of 1-phenylethyl alcohol derivatives. This work presents two promising methodologies for the introduction of controllable open metal sites in versatile crystalline coordination complexes and their application i...

To boost the design of microporous solids, we integrated a two-faced shape (as in cucurbiturils and cyclodextrins) into the building blocks of framework materials. Reported herein is a planar tritopic carboxyl linker with secondary tripod donors sprouting off both sides at the core region. The two-faced, barrel-like core region imparts a rugged 3D character to the linker architecture, obviating close packing and creating complex-shaped cavities in an Eu(iii)-carboxylate network. The merits extend beyond the interesting shape of the multiple tripod: e.g., the two sets of sulfur tripods at the barrel region, together with the triazine center, offer a rich array of donors for adsorbing Hg(ii) ions. The microporous solid also removes iodine from vapor and water, and can be easily cycled in column chromatography.

Over the last few years, numerous efforts have been made to develop white light emitting metal–organic frameworks (MOFs), due to the useful features of MOFs such as ultrahigh surface areas and tunable pore architecture. However, rare earth (RE) ions are most commonly applied as phosphors in these materials so far, raising device cost and environmental concerns. Here, we designed a new type of RE-free material capable of white light emission upon excitation at 365 nm, with the photoluminescence quantum yield in the solid state reaching 37%, fabricated by compositing carbon dots (CDs) with a Zr(IV)-based MOF. WLEDs constructed by depositing the CDs/Zr-MOF nanocomposite on a commercial UV LED chip feature CIE chromaticity coordinates of (0.31, 0.34), a high color rendering index (CRI) of 82, and a luminous efficiency of 1.7 lm W−1.

Three coordination polymers (CPs) with square-planar CuII/NiIIN4 subunits were formed in one step by subcomponent self-assembly, giving rise to an unprecedented linking variety of in situ embedded metalloligands and CuI clusters. All CPs exhibit unusual visible-light adsorption. Enhanced photocatalytic activity and high selectivity were observed in the oxidation of benzene under visible-light irradiation.

Like killing two birds with one stone, we here utilize sulfur functionalization to simultaneously mitigate the persistent instability issue of the famous Zr(IV)-based metal–organic frameworks (MOFs) and impart effective metal uptake capabilities for broader potential applications. Thioether side groups can be conveniently designed to have various sizes and configurations, and offer unique advantages for functionalizing and stabilizing highly porous frameworks. Sulfuration as such on Zr(IV)-based frameworks is meaningful, because these MOF materials, in spite of their improved stability when protected by solvents, often degrade fast upon exposure to air, therefore limiting applications that involve gas–solid interfaces. For better practical impact, here we install sulfur side chains, e.g., tris(methylthiomethyl)methyl, that are conveniently derived from inexpensive pentaerythrityl compounds. One notable advance achieved pertains to a UiO-68-type porous solid (i.e., based on terphenyl dicarboxyl linkers) featuring long-term stability in direct exposure to air, while maintaining significant mercury uptake capability from water and organic solutions. Also discovered is a cubic NU-1100-type net that offers more efficient mercury removal capability (with regards to the adsorption capacity as well as binding strength as measured from the distribution coefficient Kd) than other thioether-equipped MOF materials.

We report a highly recyclable, 2D aromatic framework that offers a unique and versatile combination of photocatalytic activity and heavy metal uptake capability, as well as other attributes crucial for green and sustainable development technologies. The graphene-like open structure consists of fused tritopic aromatic building blocks (i.e., hexahydroxytriphenylene and hexaazatrinaphthylene) that can be assembled from readily available industrial materials without the need for transition metal catalysts. Besides fast and strong binding for Pb(II) ions (e.g., removing aqueous Pb ions below the drinkable limit within minutes), the alkaline N-heterocycle units of the robust and porous host are able to quantitatively catalyse Knoevenagel reactions in water. Furthermore, the fused donor–acceptor aromatic π-systems enable environmentally friendly photoredox catalysis (PRC) utilizing the safe and abundant visible light in a commercial flow reactor. Also discussed is a new metric for benchmarking the kinetic performance of sorbents in the context of heavy metal removal from drinking water.

Here, the sulfur-functionalized zirconium(IV)-based metal-organic frameworks (Zr-MOFs) with high luminous efficiency as a novel luminophore was used to construct the electrochemiluminescence (ECL) sensor. Compared to the ligand with the aggregate state as the luminophore, the Zr-MOFs with porous structure could relieve the ECL aggregation-caused quenching (ACQ) effect, resulting in an enhancement of ECL intensity. Impressively, the coreactant tripropylamine came from tripropylamine-modified gold nanoparticles (TPrA@AuNPs) were immobilized on Zr-MOFs to form the composite (TPrA@AuNPs/Zr-MOFs), which could significantly increase the local concentration of the coreactant on the surface of electrode, shorten the electron transport distance between the coreactant and the luminophore, reduce the energy loss during the reaction and further improve the ECL efficiency of the Zr-MOFs/TPrA ECL system. Finally, epinephrine (EP) was selected as model target molecule, the developed biosensor exhibited the linear range from 1.0 × 10−8 to 1.0 × 10−2 mol L−1 with a detection limit of 3.3 × 10−9 mol L−1 (S / N = 3) for EP. This strategy offered a method to improve the ECL efficiency of luminophore for the construction of efficient sensors to detect micromolecule.

With methylthio groups flanking the carboxyl groups, the 3,3′,5,5′-tetrakis(methylthio)biphenyl dicarboxylate (TMBPD) linker forms a zirconium(IV) carboxylate porous framework featuring the topology of the UiO-67 prototype, i.e., with a face-centered-cubic array of the Zr6O4(OH)4 clusters. Thioether functionalization proves valuable because the ZrTMBPD crystal is found to be exceptionally stable not only upon long-term exposure to air but also in boiling water and a broad range of pH conditions. The hydrophobicity of the metal–organic framework can also be tuned by simple H2O2 oxidation, as illustrated in the water contact-angle measurement of the pristine and H2O2-treated ZrTMBPD solid.

We employ a two-step strategy for accessing crystalline porous covalent networks of highly conjugated π-electron systems. For this, we first assembled a crystalline metal-organic framework (MOF) precursor based on Zr(IV) ions and a linear dicarboxyl linker molecule featuring backfolded, highly unsaturated alkyne backbones; massive thermocyclization of the organic linkers was then triggered to install highly conjugated, fused-aromatic bridges throughout the MOF scaffold while preserving the crystalline order. The formation of cyclized carbon links not only greatly strengthen the precursor coordination scaffold, but more importantly, enhance electroactivity and charge transport throughout the polycyclic aromatic grid.

This article provides a critical review on two topical conductive properties, namely, electronic and ionic conductivities, related to the burgeoning porous materials field of metal–organic frameworks (MOFs). The intense current interest stems from fundamental importance as well as technological relevance for energy conversion and storage technologies (e.g., batteries, photovoltaics, fuel cells, and sensing devices), and recent progresses have been extensively reviewed. The raison d’etre of the review, consequently, lies in the personal account and reflections weaved into the fabric of current developments of the two areas. For the part of electronic conductivity, large, fused aromatics (e.g., triphenylene or even larger π-electron building blocks) figure prominently because of the intrinsically rich and diverse electronic properties that can be accessed for the synthesis of potentially highly conductive networks in the solid state. For the part of ionic conductivity, we characterize the unifying design scheme as one of the establishing strong anionicity on the host frameworks so as to facilitate the incorporation of potentially mobile protons or other cations in the porous domain. Interestingly, the pursuit of the two apparently disparate conductive properties can both be greatly facilitated by the common and abundant element of sulfur, because of its versatile chemical functionalities. For example, whereas thiol-equipped porous MOF grid can readily lock in soft and polarizable metal ions to install metal–thiolate bridges across the organic π-electron systems, and thus to potentially boost electronic transport throughout the solid-state framework, similar thiol-equipped net can be treated with oxidants (e.g., H 2 O 2 or O 3 ) to generate postsynthetically the highly ionic sulfonate function to impart strong ionic conductivity.

We report the dramatic triggering of structural order in a Zr(IV)-based metal–organic framework (MOF) through docking of HgCl2 guests. Although as-made crystals were unsuitable for single crystal X-ray diffraction (SCXRD), with diffraction limited to low angles well below atomic resolution due to intrinsic structural disorder, permeation of HgCl2 not only leaves the crystals intact but also resulted in fully resolved backbone as well as thioether side groups. The crystal structure revealed elaborate HgCl2-thioether aggregates nested within the host octahedra to form a hierarchical, multifunctional net. The chelating thioether groups also promote Hg(II) removal from water, while the trapped Hg(II) can be easily extricated by 2-mercaptoethanol to reactivate the MOF sorbent.