Organic isocyanates are readily converted to methyl amine products through their hydroboration with HBpin in the presence of a β-diketiminato magnesium catalyst. Although borylated amide and N-,O-bis(boryl)hemiaminal species have been identified as intermediates during the reductive catalysis, the overall reduction and C–O activation is metal-mediated and proposed to occur through the further intermediacy of well-defined magnesium formamidato, formamidatoborate and magnesium boryloxide derivatives. Examples of all these species have been identified and fully characterised through stoichiometric reactivity studies and the stability of the borate species leads us to suggest that, under catalytic conditions, the onward progress of the deoxygenation reaction is crucially dependent on the further activation provided by the Lewis acidic HBpin substrate. These deductions have been explored and ratified through a DFT study.

•We fabricated the PB/carbon nanopolyhedra/polypyrrole electrode for first time.•Carbon nanopolyhedra are found to promote the synthesis of PB for the first time.•Excellent electrocatalytic activity toward hydrazine detection.A novel low-cost and highly efficient hydrazine sensor based on nitrogen-doped carbon nanopolyhedra (CNP), Prussian blue (PB) and conductive polymer is synthesized. CNP containing cobalt, which were prepared via pyrolysis of the Zeolitic Imidazole Framework-67 (ZIF-67), are found to be catalytically active for the synthesis of PB. Polypyrrole (PPy) is then coated on the PB/CNP composite to provide high conductivity and an environmental stability of the PB/CNP/PPy compound. The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and electrochemical methods. The electrode modified with PB/CNP/PPy exhibits an excellent activity for the electrocatalytic oxidation of hydrazine. It demonstrated a rapid response of less 2 s, a sensitivity of 0.22 A M−1, a long linear range from 7.5 × 10−7 M to 1.7 × 10−3 M and a low detection limit (S/N = 3) of 2.9 × 10−7 M, as well as a remarkable stability and selectivity.Download high-res image (57KB)Download full-size image

Microcalorimetric techniques had been used to study the influence of different physicochemical parameters on microbial growth in different permafrosts on the Tibetan plateau. The total heat evolution of the permafrost samples amended with glucose, QT, the values of microbial growth rate constant, k, and the heat output power, Pt, were calculated from the power–time (P–t) curves. It is observed that the same coverage vegetation show similar P–t curves, which strongly suggest that the permafrost microorganisms of the homology vegetation coverage have similar structures of community. Furthermore, the vegetation degradation turns out to have significant influence, that is, the better the status of vegetation is, the higher the values of k, CFU and QT are.

Herein a series of cobalt–iron Prussian blue analogs (PBAs) containing K+ and Cs+ were synthesized in water-in-oil AOT reverse microemulsions. The size, morphology and composition of the as-prepared cobalt hexacyanoferrate (CoHCF) can be fine-tuned by conveniently varying the water-to-surfactant molar ratio (w) of the microemulsion, as confirmed by various techniques such as infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). These nanostructured PBA were thereafter employed to chemically modify electrodes to thoroughly investigate their electrochemical properties. Oxidized and reduced cobalt hexacyanoferrates were fabricated and characterized in the presence of alkali metal (Li+, Na+, K+, Rb+, Cs+) and NH4+ counteractions by cyclic voltammetry (CV). In addition, it was demonstrated that formal potentials of hexacyanoferrate (III, II) redox reactions were sensitive to the choice of electrolyte cations, and they correlated well with the sizes of hydrated Na+, K+, Rb+, Cs+ and NH4+ except for Li+. Furthermore, the samples are found to vary significantly in permeability, probably due to the difference of composition, structure and morphology of products, and the changes during charging/discharging. Finally, it is noteworthy to highlight that the nanostructures of cobalt hexacyanoferrate synthesized at w = 5–40 had much more electrochemistry stability than that synthesized in aqueous solution in all electrolytes. The potential application of the modified electrode of CoHCF films in electrochromic display was also noticed.Highlights► Cobalt hexacyanoferrate were synthesized in AOT microemulsions and aqueous solution. ► Formal potentials of hexacyanoferrate were sensitive to electrolyte cations. ► Cobalt hexacyanoferrate fabricated at w = 5–40 had enhanced electrochemistry stability. ► The modified electrode of CoHCF films in electrochromic display was also announced.

Organic isocyanates are readily converted to methyl amine products through their hydroboration with HBpin in the presence of a β-diketiminato magnesium catalyst. Although borylated amide and N-,O-bis(boryl)hemiaminal species have been identified as intermediates during the reductive catalysis, the overall reduction and C–O activation is metal-mediated and proposed to occur through the further intermediacy of well-defined magnesium formamidato, formamidatoborate and magnesium boryloxide derivatives. Examples of all these species have been identified and fully characterised through stoichiometric reactivity studies and the stability of the borate species leads us to suggest that, under catalytic conditions, the onward progress of the deoxygenation reaction is crucially dependent on the further activation provided by the Lewis acidic HBpin substrate. These deductions have been explored and ratified through a DFT study.