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Conductive metal–organic frameworks (MOFs) have recently been applied in electroactive ionic actuators due to their high surface areas and fast ion migration. However, their actuation performance needs to be promoted in terms of high conversion efficiency and large strain. Here, a soft ionic actuator is assembled by designing a hierarchical Cu‐MOFs‐based active material, which is composed of conductive Cu‐catecholate (Cu‐CAT) nanosheets covalently bridged by carboxylic multiwall carbon nanotubes (Cu‐CAT@MWCNT). Benefited from the large electromechanical deformation and rapid response rate of the Cu‐CAT@MWCNT electrodes, the assembled soft actuator exhibits large displacement of 16.6 mm with high bending strain of 0.52% (AC of ±3 V) and a high energy conversion efficiency (3.02%) with cycling stability over 10 000 cycles (in frequency range of 0.1–10 Hz). In addition, it demonstrates the capacity of gripping objects when assembled on a robot. The Cu‐CAT@MWCNT hybrid material‐based electrode points out a feasible pathway to construct soft actuators with improved performance and broadens their applications. [ABSTRACT FROM AUTHOR]

Photoreactive olefinic species are incorporated into a metal–organic framework (MOF), [Zn(bdc)(3‐F‐spy)] (1). Single crystals of 1 are shown to undergo three types of photomechanical macroscopic deformation upon illumination by UV light. To demonstrate the practical potential of this system, the inclusion of 1 in a PVA (polyvinyl alcohol) composite membrane, by exploiting hydrogen‐bonding interactions, is presented. Using this composite membrane, the amplification of mechanical stress to achieve macroscopic actuation behavior is demonstrated. These results pave the way for the generation of MOF‐based soft photoactuators that produce clearly defined mechanical responses upon irradiation with light. Such systems are anticipated to have considerable potential in photomechanical energy harvesting and conversion systems. [ABSTRACT FROM AUTHOR]

Photoreactive olefinic species are incorporated into a metal–organic framework (MOF), [Zn(bdc)(3‐F‐spy)] (1). Single crystals of 1 are shown to undergo three types of photomechanical macroscopic deformation upon illumination by UV light. To demonstrate the practical potential of this system, the inclusion of 1 in a PVA (polyvinyl alcohol) composite membrane, by exploiting hydrogen‐bonding interactions, is presented. Using this composite membrane, the amplification of mechanical stress to achieve macroscopic actuation behavior is demonstrated. These results pave the way for the generation of MOF‐based soft photoactuators that produce clearly defined mechanical responses upon irradiation with light. Such systems are anticipated to have considerable potential in photomechanical energy harvesting and conversion systems. [ABSTRACT FROM AUTHOR]

The photoinduced dynamic behavior of flexible materials has received considerable attention for potential applications, such as in data storage or as smart optical devices and molecular mechanical actuators. Until now, precisely controlling expansion and contraction with light has remained a challenge. Unraveling the detailed mechanisms of photoinduced structural transformations remains a critical step necessary to understand the molecular architecture necessary for the design of sensitive photomechanical actuators. Herein, a two‐dimensional flexible metal–organic framework [Zn2(bdc)2(3‐CH3‐spy)2]⋅H2O (Zn2‐1; H2bdc=1,4‐benzenedicaboxylic acid; 3‐CH3‐spy=3‐methylstyrylpyridine) with a positive volumetric thermal expansion coefficient of +78.78×10−6 K−1 is reported. Upon light irradiation at different wavelengths, the MOF underwent a [2+2] cycloaddition, which afforded a family of isomeric, three‐dimensional MOFs (Zn2‐2 n, n=a–d) in a single‐crystal‐to‐single‐crystal (SCSC) manner. An unprecedented phenomenon, that is, photoinduced nonlinear contraction (PINC), was observed during this conversion. The PINC is caused by conformational changes in the 3‐CH3‐spy and bdc2− ligands, the bending of metal–ligand bonds, and the local distortion of the paddle‐wheel SBUs. The formation of a "wrinkle morphology" on the crystal surface after the photoreaction was observed by AFM. This PINC behavior can broaden the studies on materials expansion and offer a photodriven approach for the future design of supersensitive photomechanical actuators. [ABSTRACT FROM AUTHOR]

A protonated mononuclear complex [Zn(Hbpvp)Cl3] (1) is assembled by solvothermal reaction of Zn(NO3)2·6H2O with 3,5-bis-(2-(pyridin-4-yl)vinyl)pyridine (bpvp) in DMF/H2O with a few drops of concentrated HCl added. Hydrogen-bonded zigzag chains of 1 crystallize over time to form large-size hollow hexagonal tubular crystals whose evolution from irregular crystal seeds is monitored by SEM and PXRD. Upon UV light irradiation, single crystals of 1 undergo a stereoselective [2+2] photocycloaddition while its Methyl Blue-coated crystals keep intact. [ABSTRACT FROM AUTHOR]

We herein report a fluorescent Zn(ii)-supported metal–organic framework (MOF) [Zn4(Hbpvp)2(BTC)3(HCOO)(H2O)2]·4H2O (1) (bpvp = 3,5-bis-(2-(pyridin-4-yl)vinyl)pyridine; H3BTC = 1,3,5-benzenetricarboxylic acid) assembled from solvothermal reactions of ZnSO4·7H2O with bpvp and H3BTC ligands. Compound 1 has a unique two-dimensional (2D) layer structure and exhibits a high sensitivity and a low limit of detection of 1.0 × 10−6 mol L−1 for both 2,4-dinitrophenol (2,4-DNP) and p-benzoquinone (p-BQ) in aqueous solutions, inferred from fluorescence quenching studies. The fluorescent intensity of 1 recovers upon removal of analytes, making it a promising recyclable dual-targeted luminescent probe for 2,4-DNP and p-BQ in water. [ABSTRACT FROM AUTHOR]

One coordination polymer [Zn2(L)2(bpe)2(H2O)2] (1) (L = 4,4′-((1,2-phenylenebis(methylene))bis(oxy))dibenzoic acid; bpe = (E)-1,2-di(pyridin-4-yl)ethene) was prepared and structurally determined. Compound 1 has a chain structure in which its pair of bpe ligands is arranged in a head-to-tail manner with their C=C bonds being close enough for a [2 + 2] cycloaddition reaction. Upon exposure to UV light, compound 1 undergoes a single-crystal-to-single-crystal (SCSC) [2 + 2] photodimerization to generate one 2D coordination polymer [Zn(L)(rctt-tpcb)0.5(H2O)] (1a) (rctt (regio cis, trans, trans)-tpcb = tetrakis(4-pyridyl)cyclobutane). The tpcb ligands in the crystals of 1a show an intriguing in situ thermal isomerisation. The nanospheres of 1 can be obtained by recrystallization in DMSO/alcohol. The nanospheres of 1a can also be readily produced from the corresponding nanospheres of 1 by the photocyclodimerization method. Compared with those of 1a, the nanospheres of 1 display highly selective sensing of Fe3+ ions over mixed metal ions through fluorescence quenching. Moreover, the nanospheres of 1a can rapidly adsorb CR (congo red), MB (methylene blue) or RhB (rhodamine B) over MO (methyl orange) from aqueous solutions. This work offers a new photoinduced post-synthetic method for the synthesis of multifunctional MOFs, which show luminescence sensing of Fe3+ ions and dye adsorption properties. [ABSTRACT FROM AUTHOR]

Aqueous soluble and stable Cu(I) molecular catalysts featuring a catenane ligand composed of two dicationic, mutually repelling but mechanically interlocked macrocycles are reported. The ligand interlocking not only fine‐tunes the coordination sphere and kinetically stabilizes the Cu(I) against air oxidation and disproportionation, but also buries the hydrophobic portions of the ligands and prevents their dissociation which are necessary for their good water solubility and a sustained activity. These catenane Cu(I) complexes can catalyze the oxidative C−C coupling of indoles and tetrahydroisoquinolines in water, using H2O2 as a green oxidant with a good substrate scope. The successful use of catenane ligands in exploiting aqueous Cu(I) catalysis thus highlights the many unexplored potential of mechanical bond as a design element for exploring transition metal catalysis under challenging conditions. [ABSTRACT FROM AUTHOR]

Extensive research has been devoted to the development of advanced oxygen reduction reaction (ORR) catalysts with functionally diverse active sites. Herein, we show a smart approach to advancing the ORR catalytic activity of a 3D porous perovskite. The facile oxidative-reductive-oxidative (O-R-O) thermal treatment cycle executed on Ag doped LaFeO 3 could stepwise switch on three different reaction sites (exsolved Ag-NPs, oxygen deficiency and Fe 4+ with optimal electron configuration) for ORR. Detailed characterizations illustrate that the ORR activity is basically derived from the hierarchically porous scaffold which provides a large surface area and enough pore volumes for mass and ion diffusion. More importantly, the unique synergistic effects among three separate kinds of reaction sites endow the speed-up of oxygen adsorption, activation and O 2− transportation. The exemplified results set out new design principles for the optimization of alternative catalysts. [ABSTRACT FROM AUTHOR]

A series of Fe(iii) complexes of β-diketonate ligands, 1-(2-pyridyl)-3-(3-pyridyl)-1,3-propanedione (L1), 1-(2-pyridyl)-3-(2-pyridyl)-1,3-propanedione (L2), 1-(2-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L3), 1-(3-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L4), 1-(3-pyridyl)-3-(3-pyridyl)-1,3-propanedione (L5) and 1-(4-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L6), viz. [Fe(L1)3] (1), [Fe(L2)3] (2), [Fe(L3)3] (3), [Fe(L4)3] (4), [Fe(L5)3] (5) and [Fe(L6)3] (6) have been structurally characterized. All but one complex (1) catalyzed the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) in near quantitative yield at 110 °C to give polymers with relatively narrow polydispersities (PDI). The comparison of in situ reaction and a reaction with preformed 1 indicated that the latter was a better catalyst, giving a higher molecular weight. Complex 2 catalyzed this reaction in a more modest yield reflecting its greater thermal stability, shorter Fe–O bonds and minimal distortion in fold angle among the isomeric complexes, suggesting that ligand dissociation is important for catalytic activity. [ABSTRACT FROM AUTHOR]

We hereby report on a pioneering and inspiring solid oxide cell which, assisted by natural gas, utilizes a bifunctional electrolysis cell configuration to effectively consume CO2 to produce CO at the cathode side and simultaneously synthesize highly valuable syngas (mixture of CO and H2) at the anode side via a one-step green process. [ABSTRACT FROM AUTHOR]

In this paper, a nonenzymatic glucose biosensor based on perovskite LaTiO3–Ag0.2(LTA) modified electrode was presented. The morphology and the composition of the perovskite LaTiO3–Ag0.2 nanomaterials were characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The LaTiO3–Ag0.2(LTA) composite was investigated by electrochemical characterization using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimal conditions, CV and chronoamperometry (I-t) study revealed that, compared with the bare glassy carbon electrode (GCE), the modified electrode showed a remarkable increase in the efficiency of the electrocatalytic oxidation of glucose, starting at around +0.70V (vs. Ag/AgCl). The prepared sensor exhibited a high sensitivity of 784.14µAmM−1 cm−2, a low detection limit of 2.1×10−7 M and a wide linear range from 2.5µM to 4mM (R=0.9997). More importantly, the LTA modified electrode was also relatively insensitive to commonly interfering species such as ascorbic acid (AA), uric acid (UA), dopamine (DA) in high potential. Moreover, the nonenzymatic sensor was applied to the determination of glucose in human serum samples and the results were in good agreement with clinical data. Electrodes modified with perovskite nanomaterials are highly promising for nonenzymatic electrochemical detection of glucose because of their high sensitivity, fast response, excellent stability and good reproducibility. [ABSTRACT FROM AUTHOR]