Facile cyclic ammonium salt with the smallest size for high performance electric double layer capacitors

A novel cyclic ammonium salt, N,N-dimethylpyrrolidinium tetrafluoroborate (P₁₁-BF₄), was successfully synthesized for the first time. The smallest cyclic structure of P₁₁-BF₄ induced high solubility and conductivity in PC, which can easier enter the micropores of activated carbon and occupy more surface area during charge/discharge process.     

铬的形态分析研究与进展

综述了Cr(Ⅲ)、Cr(Ⅵ)形态分析的发展。内容包括概述、样品分离富集、光谱分析、色谱分析等。引用文献43篇。     

Characterization of low molecular weight components of [(ViMe2SiO1/2)x(PhSiO3/2)y(SiO4/2)z], [(ViMe2SiO1/2)x(SiO4/2)y], and [(SiO4/2)x(HO1/2)y(tBuO1/2)z] silsesquioxanes by electrospray ionization fourier transform mass spectrometry (ESI-FTMS)

This paper describes the characterization of low molecular weight components of four materials using electrospray ionization Fourier transform mass spectrometry (ESI-FTMS). The materials in the current study are [(ViMe₂SiO_1/2)_x(PhSiO_3/2)_y(SiO_4/2)_z] (MTQ), [(ViMe₂SiO_1/2)_x(SiO_4/2)_y] (MQ), and [(SiO_4/2)_x(HO_1/2)_y(^tBuO_1/2)_z] (Q) silsesquioxanes. Accurate mass measurements coupled with knowledge of resin chemistry afforded siloxane composition determination that was used to propose specific structures for the oligomers. Branched or linear (T_nQ_mM_n+2m+2), and monocyclic (T_nQ_mM_n+2m) structures are predominant structures for the low molecular weight species in MTQ. For MQ and Q, more condensed structures, such as partially opened cage structures (Q_mM_2m?6 and Q_mM_2m?8), were identified. The differences between MQ, Q, and MTQ are likely attributed to differences in intrinsic structure and reactivity of T and Q building blocks. The structural information obtained for these oligomeric species will ultimately provide a better understanding of new resin materials and their associated physical properties.     

A semi-rigid bis(imidazolyl) ligand for the construction of nanoscopic supramolecules. From the molecular rectangle to the 1D coordination polymer

Reaction of the semi-rigid ligand 2,4-bis(1-imidazolylmethyl)-mesitylene (m-bimms) with CdCl₂ afforded a boat-like molecular rectangle [Cd(m-bimms)Cl₂]₂ · 1/2H₂O (1), with the orientation of the two imidazolyl arms of the ligand in syn-conformation and bridging chloride ions bisecting the macrocycle. Weak Cl· · ·H—C interations further extended the dimers into 1D infinite chains with nanoscopic channels. An analogous reaction with Cd(NO₃)₂ gave a 1D coordination polymer [Cd(m-bimms)₂(NO₃)₂]_n · 2nH₂O (2) composed of nanoscopic metallamacrocycles, where the two imidazolyl arms adopt an anti-conformation. Different anions result in different ligand conformations and thus determine the varied molecular architectures.     

Photopolymerization induced by a benzophenone derivative photoinitiator

A benzophenone derivative photoinitiator, HBP-TDI-HQ-TDI-HBP （HTCTH）, was synthesized based on 4-hydroxy benzophenone （HBP）, toluene-2,4-diisocyanate （TDI） and hydroquinone （HQ）. HTCTH was a more effective photoinitiator which had longer wavelength absorption in the UV-vis absorption spectra than the low molecular counterpart benzophenone （BP）. It showed that both rate of polymerization （Rp） and final conversion （P） increased with increase of amine and HTCTH concentration in photopolymerization.     

含氮宾或卡宾的金属羰基簇合物的结构化学研究——Ⅰ.H_2Fe_3(N-C_6H_5)(CO)_9和Fe_3(N-C_6H_5)(μ_3-CO)(CO)_9的合成和结构

含氮宾的两个三核羰基铁簇合物是由[Et_3NH][HFe_3(CO)_(11)]与C_6H_5NCO在苯中反应获得。应用四园衍射仪测定了H_2Fe_3(N-C_6H_5)(CO)_9(Ⅰ)和Fe_3(N-C_6H_5)(μ_3-CO)(CO)_9(Ⅱ)的晶体结构。晶体数据为:C_(15)H_7NO_9Fe_3(Ⅰ),空间群P2_1/a,a=18.343(2),b=9.072(1),c=11.451(1)(?),β=102.03(1)°,V=1863.7(?)~3,Z=4,D_c=2.143g/cm~3;C_(16)H_5NO_(10)Fe_3(Ⅱ),空间群P2_1/c,a=8.634(1),b=13.026(1),c=17.642(2)(?),β=97.68(1)°,V=1966.3(?)~3,Z=4,D_c=1.820g/cm结构系用直接法解出,最后R_(Ⅰ)因子为0.033,R_(Ⅱ)因子为0.027。测定结果表明,(Ⅰ)和(Ⅱ)分子均具有C_s对称性,且三个Fe原子共面,呈近似等边三角形结构。(Ⅰ)中面桥N原子以不对称方式与三个Fe原子成键;(Ⅱ)中面桥羰基以不对称方式与三个Fe原子键连。Fe-N和Fe-C键长分别在1.896-1.938(?)和2.006-2.110(?)之间。     

Study on structural variation of silica gel using Nd3+ as a probe by photoacoustic spectroscopy

The structural variations of silica gels heated at different temperatures have been firstly studied using Nd(3+) as a probe by photoacoustic spectroscopy (PAS), together with IR spectroscopy and thermal analysis. With increasing temperature, the f-f transitions of Nd(3+) show a red shift and the PA intensities increase. The PA branching vector of the transitions from ground state to 4G(5/2)+(2)G(7/2), which are hypersensitive transitions, increase and the others decrease or change little. These indicate that the covalency of the bond that Nd(3+) forms increases and the symmetry around Nd(3+) decreases, which reflects the structural variations of silica gels.     

Determination of Organophosphorus Pesticides in Soil by MMSPD-GC-NPD and Confirmation by GC-MS

A novel method, modified matrix solid-phase dispersion (MMSPD), has been developed for quantitative analysis of organophosphorus pesticide residues in soil. It was based on matrix solid-phase dispersion (MSPD) and continuous liquid-solid extraction (continuous LSE), using Florisil as sorbent and dichloromethane as the recycling solvent. Two soils with different texture and physicochemical properties were studied to validate the method. The effect of residence time of pesticides in soil was also studied. MMSPD was compared with MSPD and continuous LSE respectively. Determination was carried out by gas chromatography with nitrogen-phosphorus detection (GC-NPD). The method gave recoveries ranging from 72–105% with relative standard deviations (RSDs) lower than 15% for the pesticides studied. The limits of detection (LODs) ranged from 0.1 to 0.6 ng g⁻¹. Two pesticide residues have been detected in real soil samples from Fujian, China, using MMSPD. The pesticides were confirmed by gas chromatography-mass spectrometry (GC-MS) in a selected-ion monitoring (SIM) mode. Revised: 4 and 9 April 2006     

二苄亚砜硝酸钕的晶体结构

二苄亚砜硝酸钕Nd(NO_3)_3·[(C_6H_5CH_2)_2S0]属三斜晶系,P1空间群,晶胞参数:a=9.835(2),b=12.445(2),c=19.971(5)A,α=104.13(2)°,β=90.34(2)°γ=74.96(1)°Z=2。晶体结构用重原子法解出,经最小二乘修正后R因子为0.031。钕离子由九个氧配位,形成稍歪扭的三帽三方棱柱配位多面体,其中一个三角面由三个二苄亚砜(DBSO)提供的氧形成,其他氧原子则由硝酸根提供。平均Nd-O(DBSO)=2.379A,Nd-O(NO_3)=2.536A。     

Preparation and electrochemistry of azobenzene self-assembled monolayers on gold--long range tunneling and end-group hydrogen bonding effect

A series of thiol-functionalied azobenzene derivatives (RAzoCnSH: R=H for n=3-6, abbreviated as AzoCnSH; R=CH(3)CONH for n=4, abbreviated as aaAzoC4SH) on gold electrodes were prepared and their self-assembly and electrochemical properties were studied by cyclic voltammetry. They all formed uniform and reproducible self-assembled monolayers (SAMs) on gold and showed well-behaved voltammetric responses in aqueous solution. Both the length of the alkyl chain spacer and the H-bonding of the end acetamino group had effects on the stability and the electrochemical kinetics of the SAMs, and the effect of the H-bonding was dominant. The surface coverage of the SAMs (AzoCnSH) is gradually increased with an increase of the alkyl chain spacer length, whereas the presence of the terminal acetamino group leads to a greater increase of the surface coverage. At a low scan rate, voltammetric responses corresponding to an irreversible two-electron, two-proton reduction/oxidation of the trans-azobenzene redox center were obtained in the range of +300 mV and -800 mV, which exhibited very large peak-to-peak splitting. At a high scan rate of 500 mV/s, two steps of reversible one-electron, one-proton reduction/oxidation corresponding to the cis-isomer in azobenzene-thiol SAMs (n is odd) was clearly observed between +300 and -200 mV. The apparent electron-transfer rate is decreased with increasing distance between the azobenzene redox center and the gold electrode. The existence of the end acetamino group which restricted the conformational change during the redox process also led to a decrease of the standard rate constant, and this restriction effect is more predominant than the distance effect.