New sulfur derivatives of 2,3-dichloropyrrolo[1,2-a] benzimidazol-1-one. Demonstration of regioselective thiolate addition and X-ray diffraction structures of 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one

The reaction of thiols with the heterocyclic compound 2,3-dichloropyrrolo[1,2-a] benzimidazol-1-one (1) has been investigated as a route to new redox-active, bidentate sulfur ligands. Treatment of 1 with either methylthiol or benzylthiol in the presence of pyridine affords monosulfide compounds 2-chloro-3-methylthiopyrrolo[1,2-a] benzimidazol-1-one (2) and 2-chloro-3-benzylthiopyrrolo[1,2-a]benzimidazol-1-one (3) and the disulfide derivatives 2,3-di(methylthio)pyrrolo[1,2-a]benzimidazol-1-one (4) and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one (5). The substitution of the first chlorine group in 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one (1) occurs regioselectively at C-3 to produce 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one (2) and 2-chloro-3-benzylthiopyrrolo[1,2-a]benzimidazol-1-one (3), followed by replacement of the remaining chlorine group to furnish the disulfide compounds 4 and 5. The new thiols have been isolated by column chromatography and characterized in solution by spectroscopic methods. The molecular structures of 2-chloro-3-methylthiopyrrolo[1,2-a]benzimidazol-1-one and 2,3-di(benzylthio)pyrrolo[1,2-a]benzimidazol-1-one have been determined by X-ray crystallography. Compound 2 crystallizes as two independent molecules in the monoclinic space group P2₁/c, a = 13.221(2) Å, b = 18.478(2) Å, c = 8.948(1) Å, = 100.088(3)°, V = 2152.3(5) ų, Z = 8, and d_calc = 1.547 Mg/m³; R = 0.0354, R_w = 0.0739 for 2820 reflections with I > 2(I). Compound 5 crystallizes in the triclinic space group P-1, a = 5.180(1) Å, b = 11.494(2) Å, c = 17.243(3) Å, = 86.024(3)°, = 88.606(4)°, = 81.235(3)°, V = 1012.1(4) ų, Z = 2, and d_calc = 1.360 Mg/m³; R = 0.0354, R_w = 0.0692 for 2655 reflections with I > 2(I). The redox properties of the disulfide compounds 4 and 5 have been explored by cyclic voltammetry, where a one-electron reduction at ca. –1.10 V has been observed for each compound. The site of electron accession in has been established by carrying out molecular orbital calculations at the extended Hüuckel level on the model compound 2,3-di(thio)pyrrolo[1,2-a]benzimidazol-1-one.     

Effect of heat treatment on phase transformation of aluminum nitride ultrafine powder prepared by chemical vapor deposition

Ultrafine aluminum nitride (AlN) powders were obtained by chemical vapor deposition via AlCl₃–NH₃–N₂ system operated at various temperatures and at a same 200 cm³/min flow rate of NH₃ and N₂, respectively. It has been shown that when the reaction temperature of AlCl₃ and NH₃ was above 600°C, then crystalline AlN powder can be formed; whereas, amorphous AlN was obtained with NH₄Cl if reacted in a lower-temperature zone of the reaction chamber. The amorphous AlN powder was heat treated at 1400°C under NH₃ and N₂ atmosphere for 2 h, then the crystalline phases of the obtained powder belong to a single phase of AlN; a mixture of AlN and Al₂O₃ and only AlON, respectively. On the other hand, if crystalline AlN powder is heat treated at 1400°C under N₂ atmosphere for 2 h, the crystalline phases were composed of the major phase of AlN and a minor phase of Al₂O₃. The morphology, particle size and agglomerate size of the AlN powder were strongly dependent on the heat-treatment temperature. The particle size of AlN powder increases from 28.1 to 45.0 nm, as the heat treatment temperature increases from 800 to 1400°C.     

计时电流的因子分析-法拉第电流与充电电流的分离

基于电化学理论电流公式,用迭代目标变换因子分析法对计时电路曲线进行处理,得到分离的法拉第电流和充电电流成分,对于简单的电极过程,分离效果很好,信噪比得到提高,法拉第电流分量可用于定量分析。     

Na2S–Carbon Nanotube Fabric Electrodes for Room‐Temperature Sodium–Sulfur Batteries

A unique sodium sulfide (Na₂S) cathode is developed, which will allow the use of sodium‐free anodes for room‐temperature sodium–sulfur (Na–S) batteries. To overcome the “inert” nature of the Na₂S, a special cathode structure is developed by spreading the multi‐walled carbon nanotube (MWCNT)‐wrapped Na₂S particles onto MWCNT fabrics. Spectroscopic and electrochemical analyses reveal a series of polysulfide intermediates involved in the charge/discharge of the cell. The Na–S battery prepared in full discharge state with the Na₂S/MWCNT cathode provides a remarkable capacity of 500 A h kg^?1 (based on sulfur mass) after 50 cycles.     

Tuning the Basicity of Cyano‐Containing Ionic Liquids to Improve SO2 Capture through Cyano–Sulfur Interactions

A new approach has been developed to improve SO₂ sorption by cyano‐containing ionic liquids (ILs) through tuning the basicity of ILs and cyano–sulfur interaction. Several kinds of cyano‐containing ILs with different basicity were designed, prepared, and used for SO₂ capture. The interaction between these cyano‐containing ILs and SO₂ was investigated by FTIR and NMR methods. Spectroscopic investigations and quantum chemical calculations showed that dramatic effects on SO₂ capacity originate from the basicity of the ILs and enhanced cyano–sulfur interaction. Furthermore, the captured SO₂ was easy to release by heating or bubbling N₂ through the ILs. This efficient and reversible process, achieved by tuning the basicity of ILs, is an excellent alternative to current technologies for SO₂ capture.     

The Quest for Polysulfides in Lithium–Sulfur Battery Electrolytes: An Operando Confocal Raman Spectroscopy Study

Confocal Raman spectra of a lithium–sulfur battery electrolyte are recorded operando in a depth‐of‐discharge resolved manner for an electrochemical cell with a realistic electrolyte/sulfur loading ratio. The evolution of various possible polysulfides is unambiguously identified by combining Raman spectroscopy data with DFT simulations.     

BIS(DITHIOSQUARAMIDE) LIGANDS AND THEIR COMPLEXES WITH DIVALENT NICKEL: THERMOCHROMIC BEHAVIOUR AND UNANTICIPATED FORMATION OF 2:2 SPECIES

Abstract

Reaction of two equivalents of N-mono- or di-substituted 3-amino-4-(n-butoxy)-3-cyclobutene-1,2-diones with a 1,2-diaminoethane gave N-mono- or di-substituted 1,2-bis((2-amino-1-cyclobutene-3,4-dione)amino)-ethane derivatives (bis(squaramides)). Reaction of the bis(squaramides) with excess P₄S₁₀ gave the analogous tetrathio derivatives (bis(dithiosquaramides), LH₂) of formula (NR¹R²)C₄S₂(NHCH₂CH₂NH)-C₄S₂(NR¹R²) (R¹=n-Bu, R²=H; R¹=R²=Et, n-Bu). The new bis(dithiosquaramide) ligands were characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, electronic, and mass spectroscopic methods. The complexes of these ligands with nickel(II) were prepared, isolated and characterized. The isolated complexes are neutral 2:2 species of formula Ni₂L₂, as evidenced by results from mass spectrometry, and they exhibit thermochromic behaviour in pyridine solution. Additional spectroscopic data (IR, NMR) are consistent with the ligands being coordinated only through sulfur donor atoms and a structure for the complexes is proposed.     

Asymmetrical Fluorene[2,3‐b]benzo[d]thiophene Derivatives: Synthesis,Solid‐State Structures,and Application in Solution‐Processable Organic Light‐Emitting Diodes

A series of novel asymmetrical fused compounds containing the backbone of fluorene[2,3‐b]benzo[d]thiophene (FBT) were effectively synthesized and fully characterized. Single‐crystal X‐ray studies demonstrated that the length of the substituent side chains greatly affects the solid‐state packing of the obtained fused compounds. DFT, photophysical, and electrochemical studies all showed that the FBTs have large band gaps, low‐lying HOMO energy levels, and therefore good stability toward oxidation. Moreover, the substituents strongly influence the fluorescence properties of the resulting FBT derivatives. The di‐n‐hexyl compound exhibits intense fluorescence in solution with the highest quantum yield of up to 91 %. Solution‐processed green phosphorescent organic light‐emitting diodes with the di‐n‐butyl derivative as the host material exhibited a maximum brightness of 14 185 cd m^?2 and a luminescence efficiency of 12 cd A^?1.     

Intramolecular Homolytic Substitution of Sulfinates and Sulfinamides

A general and efficient method for the synthesis of cyclic sulfinates and sulfinamides based on intramolecular homolytic substitution (S_Hi) at the sulfur atom by aryl or alkyl radicals is described. Both alkyl and benzofused compounds can be accessed directly from easily prepared acyclic precursors. Enantiomerically enriched sulfur‐based heterocycles were formed through an S_Hi process with inversion of configuration at the sulfur atom. Cyclization of prochiral radicals proceeded with varying stereochemical outcomes, depending on the size of the incoming radical. 2‐Pyridyl and 2‐quinolyl radicals led to biaryl compounds, which result from attack onto the ortho position of the arylsulfinate rather than a thiophilic substitution.