Search

Two porous metal–organic frameworks (1 and 2) with a fsc topology based on mixed ligands have been assembled and characterized. The different pillared ligands (pyrazine for 1 and 4,4′-bipyridine for 2) significantly influence the pore size of the frameworks. Gas uptake measurements reveal that complex 1 possesses higher H2, CO2, and CH4 uptake capacities than 2, although the surface area of 1 is lower than that of complex 2. These results further experimentally prove that the pore size plays an important role in gas uptake in porous MOFs, and the slit pore with a size of ∼6 Å exhibits stronger interactions with gas molecules. [ABSTRACT FROM AUTHOR]

It is a challenge to effectively load proton carriers in COFs to improve their proton conductivity. Herein, we report a series of COF-based composites, PANa@UCOF-x (PANa: sodium polyacrylate, x: weight percentage of PANa), which were prepared by coating different proportions of superabsorbent PANa on the COF surface based on an in situ reaction strategy. Since PANa can greatly enhance the enrichment of water molecules in one-dimensional (1D) channels of COFs, these COF-based composites exhibit superprotonic conduction. At 80 °C and 95% relative humidity (RH), the proton conductivity of PANa@UCOF-10, PANa@UCOF-28 and PANa@UCOF-40 reaches 1.6 × 10−2, 5.1 × 10−2, and 1.1 × 10−1 S cm−1, respectively, which is 4–5 orders of magnitude higher than 7.4 × 10−7 S cm−1 of the original UCOF. This work not only develops a new method to improve the water content of the COF channels, but also proves the important role of ordered channels in constructing effective proton conduction pathways. [ABSTRACT FROM AUTHOR]

We report the cyclic single-crystal-to-single-crystal transformation of three hydrogen-bonded organic frameworks (HOFs), induced by the change of temperature and humidity, which clearly reveals that the –SO3−and –NH2 groups in UPC-H7 and UPC-H8 facilitate the diffusion of water molecules into their anhydrous structures to form hydrous UPC-H9. Their proton conductivity was studied under different humidity at varying temperature, showing that the proton conductivity is closely related to water molecules entering the crystal structures arising from the hydrogen bonded reorganization in combination with the triaxial single-crystal proton conductivity tests. [ABSTRACT FROM AUTHOR]

We report the development of a new type of organic semiconductor gas sensor based on a porphyrin-based hydrogen-bonded organic framework (HOF). Owing to the orderly porous structures, the decoration with rich amino sites and the n-type semiconductor nature, this HOF-based sensor exhibits selective NO2 sensing performance with ultra-fast response/recovery rates (17.6 s/15.4 s over 100 ppb) and a limit of detection lower than 40 ppb, together with high sensitivity, good reproducibility, and long-term stability at room temperature. This study demonstrates that HOF-based materials have potential application prospects in gas sensing, thereby offering a new way of thinking for the design and development of sensors. [ABSTRACT FROM AUTHOR]

This work presents the construction of a porous lead-organic framework (UPC-10) with large channels of ∼24 Å. UPC-10 shows efficient adsorption of I2 and selective adsorption of some dyes containing the SO3− group. After the adsorption of dyes, UPC-10 exhibits a CO2 gas uptake ability. Furthermore, UPC-10 could be transformed into PbS in a H2S atmosphere, and the derived PbS manifests N2 and CO2 uptake abilities. [ABSTRACT FROM AUTHOR]

NiPt hollow spheres decorated by Pt nanoparticles were synthesized by a facile wet chemical route through galvanic replacement. In situ STEM imaging and 3D reconstruction were performed to evidence the migration of Pt atoms during catalysis of CO oxidation, providing a practical insight into the structural stability of bimetallic catalysts. [ABSTRACT FROM AUTHOR]

A luminescent europium–organic framework with tubular channels based on the H4BTMIPA ligand (H4BTMIPA = 5,5′-methylenebis(2,4,6-trimethylisophthalic acid)) was assembled and characterized. The [H2N(CH3)2]+ ions as counterions are located in the channels. The cation exchange between [H2N(CH3)2]+ and metal ions resulted in complex 1 that can selectively sense Fe3+ and Al3+ ions through fluorescence quenching and enhancement, respectively. [ABSTRACT FROM AUTHOR]