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The reaction of Zn ions with β-octaalkylcorroles leads to the air oxidation of the macrocycle, with the formation of a mixture of 5- and 10-oxocorroles. Spectroscopic characterization confirms the antiaromatic character of these macrocycles. A simple synthetic protocol opens the way for more detailed studies of oxocorrole chemistry. [ABSTRACT FROM AUTHOR]

Activity trends for 22 metals and metal alloys are reported for the conversion of CO2 and CH4 to 2 : 1 H2 : CO syngas and carbon. A correlation is observed between CO2 conversion and the free energy of oxidation by CO2 on pure metal catalysts. Indium and indium alloys activate CO2 at the highest rates. We identify a new bifunctional 20 : 80 mol% Sn–In alloy that activates both CO2 and CH4 while catalyzing both reactions. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrodeoxygenation of lignin model compounds (cerulignol, creosol, guaiacol, phenol and their mixture) has been performed under mild conditions (1 atm, 25–60 °C) using a stirred slurry cathode catalytic reactor and a three-component electrolyte system: methanesulfonic acid – isopropanol – inorganic salt (KCl or NaCl). Fully saturated and deoxygenated products, such as propylcyclohexane, were obtained with high selectivity (up to 40%) and conversion (up to 90%) after 4 h of reaction time. A dual catalytic function for hydrogenation and dehydration is provided by the dispersed metal catalyst (Pt/C) and acidic protons from the electrolyte, respectively. The addition of isopropanol to the electrolyte is crucial for substrate solubilization and favoring the complete hydrodeoxygenation reaction pathways. Furthermore, the presence of salt (e.g., KCl or NaCl) in the electrolyte improved the conversion, faradaic efficiency, and carbon balance, due possibly to stabilization of protonated reactive intermediates. This study demonstrates that production of complete hydrodeoxygenation species (i.e., cyclic hydrocarbons) from diverse lignin related phenolics can be achieved via electrocatalysis at significantly lower temperatures and pressures than those in traditional thermal catalysis, in the absence of external hydrogen gas and without catalyst coking. Therefore, electrocatalysis provides new opportunities for chemical and fuel production using biomass-derived renewable feedstock. [ABSTRACT FROM AUTHOR]

Lignin is a prospective resource for renewable commodity organic chemicals and fuels. In the scheme of a sustainable biorefinery, lignin valorization is essential for enhancing the economic feasibility of the overall biomass transformation processes. Electrocatalysis and electrochemical processes are expected to play a major role in biomass valorization due to the possibility of using renewable electricity sources for in situ production of 'green' H2 and other reagents that are necessary for biomass conversion. Recent advances in the electrocatalytic hydrogenation and hydrogenolysis of lignin derivatives, including oxygenated aromatic compounds, suggest promising pathways for the synthesis of industrially relevant chemicals, such as ketone-alcohol (KA) oil, the mixture of cyclohexanone and cyclohexanol for the production of Nylon polymers. This review presents the prospect of electrocatalytic reduction approaches for a mild synthesis of lignin-based chemicals with emphasis on the potential applications of high current density electrolysis. Feasible electrocatalytic oxidation strategies for lignin depolymerization are also summarized, highlighting the fundamental differences between the electrochemical reductive and oxidative routes. Finally, challenges and opportunities for future development of the electrocatalytic pathways for lignin valorization are discussed. [ABSTRACT FROM AUTHOR]

Spinel CoCr2O4 nanostructured catalysts were prepared by a facile solvothermal method using benzyl alcohol as both a structure-directing agent and a reagent. The growth mechanism of the CoCr2O4 nanospheres was studied by Fourier-transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD). The influence of solvothermal reaction time on the morphology, structure, and oxidation states of the products was investigated through scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). It was found that early in the reaction, the CoCr2O4 spheres are coated with parasitic Co3O4 nanoparticles that disappear after long reaction times to yield smooth CoCr2O4 particles. The catalytic performance of the noble metal-free nanospheres was optimized for oxidation of methane to CO2 as evaluated at a high space velocity of 180 000 mL g−1 h−1, reaching 100% conversion below 500 °C. Importantly, samples prepared with 8 h solvothermal treatment exhibit excellent stability, maintaining 80% conversion in the presence of 10% H2O and 5 ppm SO2 after 10 cycles (∼170 h). The high stability gives these nanomaterials valuable potential for application in natural gas vehicles. [ABSTRACT FROM AUTHOR]

Silver corrolates are attractive compounds from both practical and theoretical points of view. Indeed, they play a key role in peripheral functionalization reactions occurring at the macrocycle, enabling high-yield and regioselective group insertions useful to further elaborate the molecular skeleton. In parallel, the Janus innocent or noninnocent behavior of the corrole ligand in these complexes makes their description particularly challenging. Herein, we report properties for a series of silver 3,17-disubstituted triarylcorrole complexes with various functionalities (halogens or different phenylethynyl units) that deeply affect the electron density in the macrocyclic ligand, with obvious repercussions on the observed spectral characteristics. The compounds were obtained in yields of 54–92% by applying the Stille coupling reaction with the appropriate tributylethynyl stannane. Among the complexes prepared was a derivative bearing two terminal acetylenic units which opens the way to "click" reactions for new corrole-based architectures. This corrole was structurally characterized by single crystal X-ray crystallography. The addition of substituted ethynyl groups resulted in red-shifts of the electronic absorption spectra, the largest of which was observed for the compound with two β-NO2–Ph–C≡C substituents. The remarkable influence of the NO2 groups on the electron density of this macrocycle was further demonstrated by electrochemical measurements, where an easier reduction of this complex derivative was observed as compared to the others. DFT calculations showed full delocalization over the entire p-nitrophenylethynyl unit of 5, largely affecting orbital distributions and the corresponding electronic absorptions. Although a variation of the β-substituents dramatically modifies the Soret- and Q-band positions towards lower energies for all the examined complexes, the saddling of the macrocycle resulting from functionalization is only moderate. The collected results suggest the description of these compounds as AgIII-corrolate3−, a metallocorrole with an innocent macrocyclic ligand. [ABSTRACT FROM AUTHOR]

A series of BODIPYs bearing one (4b,c), two (6a) or three (3b) glucose units attached to the meso(8) and the boron atom positions were synthesized using a Cu(i)-catalyzed Huisgen cycloaddition reaction. The resulting 1,2,3-triazole-BODIPYs were characterized by 1H, 13C and 11B NMR, HRMS, and in the case of 4a and 4b by X-ray crystallography. Triazole-BODIPYs 3b, 4b and 6a were highly permeable in cells and non-toxic to human HEp2 cells, both in the dark and upon light irradiation (IC50 ＞ 100 μM). The time-dependent cellular uptake increased with the increase number of glucose units. [ABSTRACT FROM AUTHOR]

In organic photovoltaics (OPVs), determining the energy-level alignment of a donor and an acceptor is particularly important since the interfacial energy gap between the highest occupied molecular orbital (HOMO) level of a donor and the lowest unoccupied molecular orbital (LUMO) level of an acceptor (EDHOMO–EALUMO) gives the theoretical maximum value of the open-circuit voltage (VOC). To increase the EDHOMO–EALUMO, non-fullerene acceptors, which have a lower electron affinity (EA) than C60, are receiving increasing attention. In this study, we investigated the energy-level alignment at the interface of a boron chloride subphthalocyanine (SubPc) donor and a halogenated SubPc (Cl6SubPc) acceptor using soft X-ray spectroscopy techniques. The estimated EDHOMO–EALUMO of Cl6SubPc/SubPc was 1.95 eV, which was significantly higher than that of 1.51 eV found at the interface of C60/SubPc. This increased EDHOMO–EALUMO was the origin of the enhanced VOC in OPVs. Additionally, we studied the molecular orientation of Cl6SubPc using angle-dependent X-ray absorption spectroscopy. The highly disordered Cl6SubPc molecules result in low carrier mobility, which contributes to the lower short-circuit current density of the Cl6SubPc acceptor OPVs than the C60 acceptor OPVs. [ABSTRACT FROM AUTHOR]

Doped BiVO4 is a promising photoelectrochemical water splitting anode, whose activity is hampered by poor charge transport. Here we use a set of X-ray spectroscopic methods to probe the origin and nature of localized electron states in W:BiVO4. Furthermore, using the polarized nature of the X-rays, we probe variations in the electronic structure along the crystal axes. In this manner, we reveal aspects of the electronic structure related to electron localization and observations consistent with conductivity anisotropy between the ab-plane and c-axis. We verify that tungsten substitutes as W6+ for V5+ in BiVO4. This is shown to result in the presence of inter-band gap states related to electrons at V4+ sites of e symmetry. The energetic position of the states in the band gap suggest that they are highly localized and may act as recombination centres. Polarization dependent X-ray absorption spectra reveal anisotropy in the electronic structure between the ab-plane and c-axis. Results show the superior hybridization between V 3d and O 2p states, higher V wavefunction overlap and broader conduction bands in the ab-plane than in the c-axis. These insights into the electronic structure are discussed in the context of existing experimental and theoretical reports regarding charge transport in BiVO4. [ABSTRACT FROM AUTHOR]

Hans Fischer (Munich, Germany) and S. Fergus MacDonald (Ottawa, Canada) devised efficient porphyrin syntheses based on condensation reactions of dipyrromethenes (Fischer) or dipyrromethanes (MacDonald). These historically significant processes and subsequent developments are discussed, along with monopyrrole tetramerizations that give 5,10,15,20-tetra-arylporphyrins, to show that the art of porphyrin synthesis continues to flourish. [ABSTRACT FROM AUTHOR]

A diiminoisoindolo-pyrazino unit was annulated to the β-pyrrolic position of the Zn complex of tetraphenylporphyrin, giving a macrocycle with an expanded π system in satisfactory yields. The crystal structure of this derivative evidenced the formation of a hydrogen bond network. The interaction of the β-fused isoindoline porphyrin derivative with nucleotides and nucleic acids has been investigated. [ABSTRACT FROM AUTHOR]

The atmospheric chemistry of several gases used in industrial applications, C4F9OC2H5(HFE-7200), C4F9OCH3(HFE-7100), C3F7OCH3(HFE-7000) and C3F7CH2OH, has been studied. The discharge flow technique coupled with mass-spectrometric detection has been used to study the kinetics of their reactions with OH radicals as a function of temperature. The infrared spectra of the compounds have also been measured. The following Arrhenius expressions for the reactions were determined (in units of cm3molecule−1s−1): k(OH + HFE-7200) = (6.9+2.3−1.7) × 10−11exp(−(2030 ± 190)/T); k(OH + HFE-7100) = (2.8+3.2−1.5) × 10−11exp(−(2200 ± 490)/T); k(OH + HFE-7000) = (2.0+1.2−0.7) × 10−11exp(−(2130 ± 290)/T); and k(OH + C3F7CH2OH) = (1.4+0.3−0.2) × 10−11exp(−(1460 ± 120)/T). From the infrared spectra, radiative forcing efficiencies were determined and compared with earlier estimates in the literature. These were combined with the kinetic data to estimate 100-year time horizon global warming potentials relative to CO2of 69, 337, 499 and 36 for HFE-7200, HFE-7100, HFE-7000 and CF3CF2CF2CH2OH, respectively. [ABSTRACT FROM AUTHOR]

Paramagnetic CpCr[(RN)2C6H4] compounds (R = SiMe3,CH2CMe3 and Ph) were treated with R'N3 azides to generate chromium imido complexes, CpCr[(RN) 2C6H4](NR'), with R' = adamantyl, aryl or SO2Ar. The H-atom abstraction reactivity of the imido complexes differed as the R and R' substituents were varied. [ABSTRACT FROM AUTHOR]