Application of a Self-developed Proton Transfer Reaction-Mass Spectrometer to On-line Monitoring Trace Volatile Organic Compounds in Ambient Air

Real-time and on-line monitoring volatile organic compounds(VOCs) are valuable for real-time evalua- ting air quality and monitoring the key source of pollution. A self-developed proton transfer reaction-mass spectrometer(PTR-MS) was constructed and applied to on-line monitoring trace VOCs in ambient air in Hefei, China. With the help of a self-developed catalytic converter, the background signal of the instrument was detected and the stability of the instrument was evaluated. The relative standard deviation of signal at m/z 21 was only 0.74% and the detection limit of PTR-MS was 97 part per trillion(97×10^-12, volume ratio). As a case of the air monitoring in Hefei, the ambient air at Dongpu reservoir spot was on-line monitored for 13 d with our self-developed PTR-MS. Meanwhile, a solid-phase micro-extraction(SPME) technique coupled to gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS) was also used for the off-line detection of the air. The results show that our self-developed PTR-MS can be used for the on-line and long-term monitoring of VOCs in air at part per trillion level, and the change trend of VOCs concentration monitored with PTR-MS was consistent with that detected with the conventional SPME-GC-MS. This self-developed PTR-MS can fully satisfy the requirements of air quality monitoring and real-time monitoring of the key pollution sources.     

Three New Compounds Based on 4,4'-Azo-1,2,4-triazol-5-one: Synthesis,Crystal Structure and Thermal Properties

A series of guanidine salts of 4,4'-azo-1,2,4-triazol-5-one with guanidine(1), aminoguanidine(2), diaminoguanidine(3) and triaminoguanidine(4) was prepared. Compounds 2-4 were characterized by infrared(IR) spectroscopy, elemental analysis and single-crystal X-ray diffraction. Thermal decomposition processes of compounds 1-4 were investigated by differential scanning calorimetry(DSC), and all the compounds showed good thermal stability up to 190℃. Moreover, these four guanidine salts are more unstable with the increasing number of amino groups. Thermal stability parameters(T_e,0 and T_b) and thermodynamic functions(ΔS^≠, ΔH^≠ and ΔG^≠) for compounds 1-4 were calculated. The constant-volume combustion heats(Δ_cU) for compounds 2-4 were determined and tended to increase with the increase of the number of amino groups. The calculated standard molar enthalpies of formation(Δ_fH⁰m) of compounds 2-4 are -541.04, -178.67 and -83.08 kJ/mol, respectively. The impact sensitivities results indicate that these four energetic salts are less sensitive than 1,3,5-trinitrotriazacyccohexane(RDX) and 1,3,5,7-tetranitrotetraqza-cyclo-octane(HMX).     

塞来昔布的合成及其光谱性质研究

采用甲醇钠为催化剂,乙醇为溶剂,对甲基苯乙酮、三氟乙酸乙酯催化合成了中间体4,4,4-三氟-1-(4-甲苯基)-1,3-丁二酮.中间体和对肼基苯磺酰胺盐酸盐发生环合反应得到粗品塞来昔布(Celecoxib,CLX),重结晶、抽滤、干燥,得到了纯度为99.7;的CLX.以二氯甲烷为溶剂,采用溶剂蒸发法培养出化合物CLX晶体,通过单晶衍射仪、HPLC-MS、1 HNMR、FT-IR、UV-vis、TG-DTA对CLX进行检测和表征,揭示了CLX的微观结构和内在规律性.单晶衍射仪检测到了衍射数据、部分健长和键角数据,准确判断出CLX为单晶化合物.HPLC-MS检测到了CLX分子的质量信息,CLX在电离室中发生了脱氢反应,最大相对丰度的质荷比(m/z)为379.9381.1 HNMR检测到了CLX分子有6组峰,积分值对应不同的化学位移,推断出CLX的氢核数目为14.FT-IR揭示出CLX分子内部的各元素之间的化学键键型,CLX为含有C-F键、苯环、吡唑环、二取代苯的伯酰胺.UV-vis检测出了CLX在244.1nm、250.2 nm、259.7 nm有三个吸收峰,为共轭苯环π→π*电子跃迁产生的,最大吸收波长为250.2 nm,为企业CLX产品质量检测,推测CLX的结构提供了实验依据.TG-DTA检测出CLX的质量变化与热效应,CLX的DSC曲线在170.8℃、371.6℃存在二个吸热峰,分别为CLX的相变峰、分解峰.     

部分硫/硒(S/Se)红外非线性晶体原料的快速合成方法研究

含有硫/硒(S/Se)元素的部分化合物在现有中红外非线性晶体材料中占据相当重要的地位.高纯多晶原料是生长优质S/Se光学晶体的基础,但常规合成方法存在周期长、数量少等缺点.为此,针对部分S/Se化合物,我们对传统的合成方法进行优化、改进,实现GaSe,AgGaSe2,AgGaGeS4,AgGaGe5Se12等的快速合成,单次合成原料200～300 g,合成周期小于48 h,经过粉末衍射(XRD)测试表明合成的原料质量较好,能够生长出较大尺寸单晶.文中对快速合成方法的机理、存在的问题等也进行了相关讨论.     

基于一维[H_2Mo_4O_(14)]_n~(2n-)链和双吡啶双酰胺配体的三维锌配合物的合成、结构与性能

选择柔性的双吡啶双酰胺配体N,N'-双(3-吡啶甲酰胺基)-1,2-乙烷(3-bpye)、钼酸铵和氯化锌在水热条件下自组装制备了一个基于一维[H_2Mo_4O_(14)]_n~(2n-)链的三维锌配合物[Zn(3-bpye)(H_2Mo_4O_(14))(H_2O)_2],并通过元素分析、红外光谱、热重分析等技术手段研究了配合物的结构,并利用X射线单晶衍射分析进行了晶体结构表征。结构解析揭示标题配合物是三斜晶系,P-1空间群,晶胞参数a=0.61310(3)nm,b=1.04750(6)nm,c=1.06540(6)nm,α=78.5540(10)°,β=77.5350(10)°,γ=89.9050(10)°,V=0.65420(6)nm~3,M_r=981.47,D_c=2.491 g/cm~3,Z=1,F(000)=468,R_1=0.0290,ωR_2=0.1068。标题配合物中,金属锌离子连接一维[H_2Mo_4O_(14)]_n~(2n-)链形成一种二维无机双金属层[Zn(H_2Mo_4O_(14))]_n,相邻的层间又通过双齿配体3-bpye连接形成三维CdSO_4拓扑的骨架结构。配合物表现出强的荧光发射特性,而且其在紫外光照下对亚甲基蓝和罗丹明B均有明显的催化降解活性。     

Multicomponent reactions for the synthesis of new cyclopentadienephosphonate derivatives in water

A series of polysubstituted cyclopentadienephosphonate derivatives were synthesized via one-pot multicomponent reactions of primary amines and phosphites with activated acetylenic compounds in water as the solvent at room temperature.

Particularly valuable features of this method include high yields of products, broad substrate scope, short reaction time and a straightforward procedure.     

多金属氧酸盐修饰的过渡金属配合物的催化效果和电化学行为

基于水热技术,合成了多金属氧酸盐修饰的2种新的过渡金属配合物[Cu（dmbipy）²（SiW¹²O⁴⁰）][Cu（dmbipy）（H₂O）₃]·3H₂O（1）和{（Hdmphen）²[Ag₂（dmphen）²（SiW¹²O⁴⁰）]}_n（2）（dmbipy=4,4’-二甲基-2,2’-联吡啶,dmphen=2,9-二甲基-1,10-菲咯啉）。配合物1的最小不对称单元包含2种不同的Cu（Ⅱ）单元,其中Cu（Ⅱ）离子都采用了五配位的模式,并且水分子也参与了配位。氢键将不同的Cu（Ⅱ）单元连接形成了一维链,并延伸至二维层。在配合物2中,多金属氧酸盐连接Ag（Ⅱ）离子形成一维链。氢键和π…π堆积作用将一维链拓展成了二维层。     

Nuclear magnetic resonance study of the ferroelastic phase transition of order-disorder type in [N(C2H5)4]2CdCl4

This study uses nuclear magnetic resonance (NMR) techniques to examine the detailed changes in [N(C₂H₅)₄]₂CdCl₄ around its phase transition at the temperature T_C = 284 K. The chemical shifts and spin-lattice relaxation times in the rotating frame (T_1ρ) were determined from ¹H magic angle spinning (MAS) NMR and ¹³C cross-polarization (CP)/MAS NMR spectra. The two sets of inequivalent ¹H and ¹³C nuclei in CH₃ and CH₂ were distinguished. A ferroelastic phase transition was observed at T_C, without structural symmetry change. The phase transition is mainly attributed to the orientational ordering of the [N(C₂H₅)₄]⁺ cations, and the spectral splitting at low temperature is associated with different ferroelastic domains.     

Supramolecular assemblies of azobenzene‐β‐cyclodextrin dimers and azobenzene modified polycaprolactones

Click chemistry is employed to couple two β‐cyclodextrins at both ends of azobenzene moiety yielding dumbbell‐shaped amphiphiles (AZO‐β‐CD dimer) constructed by rigid aromatic building blocks as “body”, and hydrophilic cyclodextrins as “head” with almost quantitative yield and purity. Bulk aggregates formed by the self‐assembly of the supraamphiphiles through π–π stacking and hydrophobic effect are observed. Meanwhile, the rationally designed polyesters, named as AZO‐PCL with controllable molecular weights and low polydispersities, are successfully synthesized by ring‐opening polymerization of ε‐caprolactone in the presence of p‐aminoazobenzene as initiator. In the aqueous phase, very stable spherical particles are formed by host–guest interactions between AZO‐β‐CD and AZO‐PCLs; the spherical aggregates inherit the photo‐responsiveness of azobenzene. The detailed aggregation and disaggregation behaviors are fully investigated by TEM, SEM, NMR, 2D NOESY, IR, UV and XRD measurements. Compared to the previous works, our newly developed system can be fabricated with more readily manners, avoiding tedious synthetic process; the reversible and dynamic nature of the non‐covalent interactions also can be modulated alternatively by UV or visible light. Thus, such dumbbell‐shaped supra‐amphiphiles are of great potential applications in the controlled delivery systems. Copyright © 2014 John Wiley & Sons, Ltd.     

太阳能材料CuInS2的晶体结构、电子和光学特性

用全电势线性缀加平面波法加局域轨道方法调查了黄铜矿半导体CuInS2的结构、电子和光学特性。我们计算的带隙0.17 eV是直接的,其它实验和理论也表明这种材料有一个直接带隙。在 In 4d和S 3p轨道之间有相当强的杂化,构成了(InS2)4-阴离子。我们计算的反射率光谱,介电函数的实部和虚部,消光系数和折射率和实验结果取得了很好的一致。