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Hybrid polyoxometalate–porphyrin copolymeric films can be obtained by the electro-oxidation of 5,15-ditolyl porphyrin (H$_{\mathbf{2}}$T$_{\mathbf{2}}$P) and zinc-$\beta $-octaethylporphyrin (ZnOEP) in the presence of the Lindqvist-type polyoxovanadates $\mathrm{TBA}_{2}[\mathrm{V}_{6}\mathrm{O}_{13} \lbrace (\mathrm{OCH}_{2})_{3}\mathrm{CNHCO} (4\mbox {-}\mathrm{C}_{5}\mathrm{H}_{4}\mathrm{N})\rbrace _{2}]$ (Py-V$_{\mathbf{6}}$O$_{\mathbf{13}}$-Py). The photocatalytic properties of these films have been studied for the reduction of silver and platinum ions. In these hybrid materials, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to the polyoxovanadates catalysts.

We describe here an immobilization method of four Keggin‐type polyoxometalates (POMs) ([H2W12O40]6−, [BW12O40]5− [SiW12O40]4−, [PW12O40]3−) by using the reaction with an ionic liquid, 1‐butyl‐3‐vinylimidazolium (BVIM) bromide. The reaction yields a hybrid material (BVIM‐POM) as a water‐insoluble salt. The chemical structure of both compounds is preserved, as indicated by infrared spectroscopy (FT‐IR), although with a reduced crystallinity (shown by X‐ray diffraction analysis) due to a decrease of water content (shown by thermogravimetric analysis). Cross polarization 1H‐31P NMR evidenced the presence of BVIM in the structure of (BVIM)3[PW12O40]. The salt is mixed with carbon powder and Nafion to prepare an ink and casted on glassy carbon electrodes. The electrochemical behavior of immobilized POMs material is preserved. The electrochemical activity for nitrite reduction is measured by cyclic voltammetry and differential electrochemical mass spectrometry (DEMS). It was observed that the reduction current of 10 mM HNO2 at pH 1 in 0.5 M Na2SO4 is enhanced in the presence of these hybrid materials. DEMS has evidenced the formation of nitrous oxide (N2O) at potentials more positive compared to the use of parent POMs in solution. [ABSTRACT FROM AUTHOR]

In this work we describe the use of bimetallic silver‐copper macroporous foams for electrochemical nitrate reduction in acidic conditions (pH 2, 0.1 M NaClO4). By carefully selecting the composition of the electrodeposition bath, we have successfully prepared foams with atomic percentage varying from Ag dominant to Cu dominant. Also, we have succeeded to obtain morphologies that vary between the one specific to pure Ag foam to the one specific to pure Cu foam. We have shown that these foams contain a pure silver phase and also a silver‐copper alloy. The electrochemical active surface area of the foams depends both on the morphology as well as on the atomic composition. These materials were used for the first time as catalysts for nitrate electrochemical reaction (NO3RR). Both liquid and gaseous products were quantified with several analytical techniques. It was shown that bimetallic foams present superior faradaic efficiency (FE) towards liquid products in comparisons with pure silver and copper foams, suggesting a synergetic contribution from both metals. The Ag94Cu6 (AgCu10) foam shows a FE as high as 92 % towards liquid products and the lowest FE (3 %) towards the undesired product, i. e. nitrous acid. Also, this material shows a better stability than pure copper materials in the presence of nitrate in acidic conditions. [ABSTRACT FROM AUTHOR]

Two diphosphanes with variable-length ligands tested as nucleophiles to prepare isoporphyrin copolymers in the presence of ditolylporphyrin of zinc (ZnT2P) prevented the oxidation of the diphosphine ligand. This paper demonstrates the power of this approach and describes the photoelectrocatalytic properties. The obtained copolymers were characterized by UV–vis spectroscopy, X-ray photoelectron spectroscopy, atomic force micrograph (AFM), EQCM (Electrochemical Quartz Cristal Microbalance) and electrochemistry. Their impedance properties (EIS) were studied and their photovoltaic performances were also investigated by photocurrent transient measurements under visible light irradiation. [ABSTRACT FROM AUTHOR]

The article in ChemCatChem discusses the immobilization of Keggin-type polyoxometalates (POMs) using an ionic liquid, resulting in a hybrid material (BVIM-POM) that enhances nitrite electroreduction. The hybrid material is prepared as a water-insoluble salt and tested on glassy carbon electrodes, showing preserved electrochemical behavior and increased activity for nitrite reduction. Differential electrochemical mass spectrometry (DEMS) reveals the formation of NO and N2O during the process. For more details, readers can refer to the Research Article by Laurent Ruhlmann, Vasilica Badets, and their colleagues. [Extracted from the article]

The electrochemical characteristics of covalent derivatives of the higher fullerenes C70, C76, C2v-C78, and D3-C78, with bis(alkoxycarbonyl)methano addends, were studied by cyclic voltammetry and/or steady-state voltammetry. Several characteristics were found to be common to lower adducts (mono- to tetrakisadducts) of all the fullerenes examined including C60. All derivatives underwent several electrochemical reduction and one or two oxidation steps.

Electrochemical analysis and ab initio calculations were done to examine the structure of donor- and/or acceptor-substituted tetraethynylethenes (TEEs) and to assess the ability of their conjugated carbon core to induce electronic communication between pendant functionality. The results revealed that the presence of one redox center on the TEE core exerts negligible effect on the redox characteristics of the other centers. It was also found that the alkyne moieties are responsible for the delocalization of charges into the carbon framework after electrochemical reduction. Such charge delocalization, in turn, leads to cis-trans isomerization.

Trinuclear copper(II/I) complexes of hexakis(bipyridyl)cyclotriveratrylene, (CTV) ligand exhibit redox controled conformational isomerism. Electrochemical method, along with 1H-NMR and mass spectroscopy, characterize these complexes. The ligand catechol gives only one bistable complex with Cu(II), which helps to identify the conformations observed for CTV complexes. The variable temperature cyclic voltametry gives thermodynamic data and equilibrium constant. The effect of noncoordinating and coordinating solvents is also discussed.

The combination of more stackable octaethylporphyrins (OEPs) in a cofacial arrangement on the upper rim of a (cone) crown calix[4]arene spacer is reported, where the distance separating the calixarene rim and the porphyrin itself is shortened in the new generation Pacman species. Electrochemically induced molecular motions are observed for the development of bistable devices due to the flexible nature of the calixarene.

Abstract: A CuI bis‐phenanthroline rotaxane was prepared by using the [2+2] cycloaddition‐retroelectrocyclization (CA‐RE) reaction to graft a bulky dicyanoquinodimethane (DCNQ) stopper. The electronic properties were investigated with electrochemical and photophysical techniques, in parallel with three reference compounds, namely, the DCNQ derivative alone, the DCNQ‐based phenanthroline ligand, and an analogue CuI complex lacking the DCNQ moiety. In all the systems containing the DCNQ unit, the lowest electronic excited states are centered thereon, with the singlet level (S1) located at about 1.0 eV, as suggested by TDDFT calculations. Accordingly, in the DCNQ‐equipped rotaxane, the typical metal‐to‐ligand charge‐transfer luminescence of the CuI center is totally quenched. Ultrafast transient absorption and emission studies show that, in the rotaxane, the final sink of photoinduced processes is the lowest singlet state of the DCNQ moiety (S1), which exhibits strong charge‐transfer character and a lifetime of 0.4 ps. Its deactivation leads to population of another excited state with a lifetime of 1.3 ps, which can be the related triplet state (T1) or a vibrationally hot level (hot‐S0). Notably, S1 also shows stimulated fluorescence in the near‐infrared (NIR) region between 1100 and 1500 nm, corroborating the TDDFT prediction. This unusual finding opens up the study of ultrashort‐lived NIR luminescence in organic donor–acceptor systems. [ABSTRACT FROM AUTHOR]

Abstract: Semiquinones (SQ) are generated in photosynthetic organisms upon photoinduced electron transfer to quinones (Q). They are stabilized by hydrogen bonding (HB) with the neighboring residues, which alters the properties of the reaction center. We designed, synthesized, and investigated resorcin[4]arene cavitands inspired by this function of SQ in natural photosynthesis. Cavitands were equipped with alternating quinone and quinoxaline walls bearing hydrogen bond donor groups (HBD). Different HBD were analyzed that mimic natural amino acids, such as imidazole and indole, along with their analogues, pyrrole and pyrazole. Pyrroles were identified as the most promising candidates that enabled the cavitands to remain open in the Q state until strengthening of HB upon reduction to the paramagnetic SQ radical anion provided stabilization of the closed form. The SQ state was generated electrochemically and photochemically, whereas properties were studied by UV/Vis spectroelectrochemistry, transient absorption, and EPR spectroscopy. This study demonstrates a photoredox‐controlled conformational switch towards a new generation of molecular grippers. [ABSTRACT FROM AUTHOR]