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With the aim of producing a photomechanical material for incorporation in soft microrobots, a one‐dimensional diene coordination polymer (CP) [Cd(F‐bpeb)(3‐CBA)2]n (CP1, F‐bpeb=4,4′‐((1E,1′E)‐(2,5‐difluoro‐1,4‐phenylene)bis(ethene‐2,1‐diyl))dipyridine, 3‐HCBA=3‐chlorobenzoic acid) was synthesized and characterized. Irradiation of CP1 with ultraviolet (UV) or visible light causes [2+2] photocycloaddition reactions resulting in the introduction of crystal strain which triggers various types of crystal movements. Composite films of CP1‐PVA (SC) fabricated by dispersing CP1 crystals into polyvinyl alcohol (PVA) solution allow amplification of the crystal movement so that the film strips exhibit fast and flexible curling upon photoirradiation. The composite films may be cut into long rectangular strips and folded to simulate soft microrobots which exhibit a variety of fast, flexible and continuous photomechanical movements resembling a human performing various gymnastic exercises. [ABSTRACT FROM AUTHOR]

An investigation of the coordination polymer, [Cu2(Me2pz)(TCNQ)] (Me2pz = 2,5-dimethylpyrazine) is described. The structure of [Cu2(Me2pz)(TCNQ)] is comprised of 2D sheets with mean plane sheet-to-sheet separations closer than that of graphene sheets in graphite. Electrical conducticity measurements on the framework indicate semiconductor behaviour with a σ300K = 9.8 × 10−8 S cm−1 and an Ea = 0.43(3) eV. Density functional theory studies reveal a band structure comprised predominatly by donor TCNQ and acceptor Me2pz ligand-p oribtals. This investigation also resulted in the formation of Cu(TCNQ) (phase I) from the reaction mixture that yielded [Cu2(TCNQ)(Me2pz)]. A redetermination of the crystal structure of Cu(TCNQ) is reported. [ABSTRACT FROM AUTHOR]

The effect of core geometry constraints of hydrogenase H-cluster analogues on reduction chemistry have been explored by a combination of structural, electrochemical and IR spectroelectrochemical (IR-SEC) studies. A series of phosphido-bridged diiron hexacarbonyl complexes, Fe2(µ2-PPh2(CH2) x PPh2)(CO)6, x = 2 (2P) and 4 (4P) and previously reported with x = 3 (3P) and the unlinked bis-diphenylphosphido (DP) analogues were investigated. The X-ray structures of the neutral complexes demonstrate the effect of the linking group on the Fe2P2 core geometry with P–Fe–Fe–P torsion angles of 95 (2P), 101 (3P), 108 (4P) and 109° (DP) and a twisting of the Fe(CO)3 fragments from an eclipsed geometry (2P , 3P and DP) for 4P. For all four compounds the primary reduction process involves two close-spaced one-electron reactions (E1 and E2) with a systematic trend to more negative reduction potentials with a shorter link between the bridging phosphorus atoms. This reflects the greater constraint that the bridging group places on the adoption of a planar 2Fe2P geometry. The sensitivity of the core geometry is greater for E2 than E1 and this impacts the stability of the monoanion with respect to disproportion (K disp(298 K) = 0.02 (2P), 2.4 (3P) and 3540 (4P and DP)). 4P has a stable dianion and gives reversible cyclic voltammetry at 298 K and is quasi-reversible at 253 K, whereas the response of 2P is irreversible at 298 K, with two distinct daughter products, but becomes quasi-reversible at 253 K. IR-SEC measurements enabled elucidation of the spectra and time evolution of the reduction products. These results are consistent with a bimolecular reaction giving a distinct reduced product modelled as a dimeric, 4Fe species. The sensitivity of the reduction chemistry of the bridged diiron compounds underpins their utility as catalytic proton reduction catalysts and the systematic trends delineated in this investigation provide the framework for charting the path of their redox-coupled chemical reactions. Integration of IR spectroelectrochemical and electrochemical simulation of the series of phosphido-bridged diiron hexacarbonyl complexes, Fe2(µ2-PPh2(CH2) x PPh2)(CO)6, x = 2 (2P) and (4P) and previously reported x = 3 (3P) and bis-diphenylphosphido (DP) analogues have allowed delineation of the impact of constraints on the 2Fe2P core geometry on the reduction chemistry. The sensitivity of the reduction chemistry of the bridged diiron compounds underpins their utility as catalytic proton reduction catalysts and the systematic trends delineated in this investigation provide the framework for charting the path of their redox-coupled chemical reactions. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks possessing relatively large pores, high surface areas, and unsaturated metal sites are attractive materials for use as electrocatalysts in the reduction of N2 to NH3. In this work, a MIL-101(Fe)/MoS3 hybrid catalyst, prepared by using a precursor-transformation strategy, is shown to be an effective electrocatalyst for the N2 reduction reaction (NRR). Under solvothermal conditions, micro-sized octahedral MIL-101(Fe) precursors are converted into ultra-small nanodots, while amorphous MoS3 derived from (NH4)2MoS4 provides a surface suitable for anchoring the MIL-101(Fe) nanodots. The as-prepared composite exhibits excellent electrocatalytic activity and durability for the NRR with a Faraday efficiency of 36.71% and an NH3 yield of 25.7 µg h−1 mgcat−1 at −0.1 V vs. RHE in 0.1 M HCl. The results show that the dispersion and adherence of MIL-101(Fe) nanodots on amorphous MoS3 improves the exposure of active centers and aids mass transfer, resulting in greatly enhanced catalytic activity and stability. [ABSTRACT FROM AUTHOR]

A large number of researches are conducted to analyze and demonstrate the synthesis, characterization and voltammetry of [[bmim].sub.4][[alpha]-[S.sub.2][W.sub.18] and its related salts, the reduction of which leads to precipitation of arrays on the surface. The ability of the cations and the polyoxometalate anions to form ion clusters and to the lower solubilities of the reduced salts are found to highly affect the dissolution of the reduced surface films.

A demonstration that the acid-induced assembly of two interesting W/Cu/S supramolecular compounds, [Et4N]3[(WS4Cu2)2-(mu-CN)3].2MeCN and [PPH4][WS4Cu3(mu-CN)2].MeCN from performed clusters [Et4N or PPh4]2WS4(CuCN)2 is presented. The general strategy of using a weak acid to remove cynaide without causing decomposition of the cluster appears to be suitable only at lower concentrations of acetic acid.

Using simple methods to obtain efficient catalysts has been a long-standing goal for researchers. In this work, the employment of a one-pot pyrolysis reaction to achieve molecular confinement, has led to the preparation of ruthenium (Ru)-based nanoclusters in a carbon matrix. A unique feature of the synthetic approach employed is that solvent and substrates were calcined together. As solvent evaporates, during calcination, the substrates form a dense solid which has the effect of limiting the aggregation of Ru centers during the carbonization process. The catalyst prepared in this simple manner showed an impressively high activity with respect to the hydrogen/oxygen evolution reaction (HER/OER). The Ru nanoclusters (Ru NCs), as the hydrogen evolution reaction (HER) catalysts, require ultralow overpotentials of 5 mV and 5.1 mV at −10 mA·cm−2 in 1.0 M KOH, and 0.5 M H2SO4, respectively. Furthermore, the catalyst prepared by the one-pot method has higher crystallinity, a higher Ru content and an ultrafine cluster size, which contributes to its exceptional electrochemical performance. Meanwhile, the RuOX nanoclusters (RuOX NCs), obtained by oxidizing the aforementioned Ru NCs, exhibited good oxygen evolution reaction (OER) performance with an overpotential of 266 mV at 10 mA·cm−2. When applied to overall water splitting, Ru/RuOX nanoclusters as the cathode and anode catalysts can reach 10 mA·cm−2 at cell voltages of only 1.49 V in 1 M KOH. [ABSTRACT FROM AUTHOR]