大气飘尘中多环芳烃的超声波萃取- 恒能量同步荧光法测定

采用超声波萃取大气飘尘样品中的多环芳烃,样品不需纯化,直接可用于同步荧光分析,超声波萃取效率高,萃取时间短;采用恒能量同步荧光法对多环芳烃进行定性定量,相关系数r>0.999 1,检出限(3δ)在0.013~4.4 ng之间,回收率为80%~132%。     

Synthesis,Electronic Properties and WOLED Devices of Planar Phosphorus‐Containing Polycyclic Aromatic Hydrocarbons

We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs).     

大气气溶胶中多环芳烃的特征光谱检测技术研究

采用紫外-可见分光光度法、傅立叶红外光谱法和恒能量同步荧光分析法进行实验室模拟测试,检测蒽、苯并[a]芘、荧蒽、苯并[k]荧蒽、苯并[ghi]苝5种多环芳烃(PAHs),对比分析了各检测技术的灵敏度、精密度、检出限、线性范围、混合组分图谱分离度等指标。结果表明,恒能量同步荧光法的选择性最好,灵敏度(0.046 0~1.360 5Io.ng-1)和精密度(平均空白的RSD为4.1%)均最高,检出限(0.038~0.427μg.L-1)最低,线性范围较宽(0.126~7 157μg.L-1),是3种光谱分析法中最适合无分离在线检测气溶胶中多组分PAHs的方法。将该方法应用于实际大气环境气溶胶样品中各PAHs成分的定性鉴别和定量检测,5种PAHs均被检出,各物质的特征峰分离效果好,峰形明显,能满足实际测量的分析要求。     

The synthesis and the solvent and substituent effect on the spectroscopic characteristic of 3-ethyl-2-(p-substitued styryl)benzothiazolium iodides

The photophysical and photochemical properties of p-substitued 2-styryl-ethylbenzothiazolium iodides, possessing different electron-withdrawing or electron-donating groups are described. The dyes were prepared by the condensation of 3-ethyl-2-methylbenzothiazole salts with p-substituted benzaldehydes. The synthesis of suitable substrates is presented as well. We describe here the absorption, emission spectra and the luminescence quantum yield of hemicyanine dyes (SH) measured in 11 different organic solvents of varying polarity. Molecular structure of the synthesized dyes was established by (1)H NMR, electronic absorption and fluorescence spectrometry. The spectral data confirmed that all the compounds exist in E-configuration of their styryl residues. The planar molecular conformation is typical for the compounds with five-membered side aromatic moieties (for example benzothiazole). The compounds possessing N-alkyl substituent in phenyl ring, in contrast to the compounds with other substituents, exhibit low fluorescence quantum yield in THF solution. This indicates that for N-alkyl derivatives the non-radiative processes are much more effective than the radiative ones. The electronic absorption and fluorescence emission spectra of tested dyes demonstrate high sensitivity to the nature of substituent introduced into the aromatic ring.     

Functionalization of Pentacene: A Facile and Versatile Approach to Contorted Polycyclic Aromatic Hydrocarbons

In this work, a facile and versatile strategy for the synthesis of contorted polycyclic aromatic hydrocarbons (PAHs) starting from the functionalized pentacene was established. A series of novel PAHs 1 – 4 and their derivatives were synthesized through a simple two-step synthesis procedure involving an intramolecular reductive Friedel–Crafts cyclization of four newly synthesized pentacene aldehydes 5 – 8 as a key step. All the molecules were confirmed by single-crystal X-ray diffraction and their photophysical and electrochemical properties were studied in detail. Interestingly, the most striking feature of 1 – 4 is their highly contorted carbon structures and the accompanying helical chirality. In particular, the optical resolution of 2 was successfully achieved by chiral-phase HPLC, and the enantiomers were characterized by circular dichroism and circularly polarized luminescence spectroscopy. Despite the highly nonplanar conformations, these contorted PAHs exhibited emissive properties with moderate-to-good fluorescence quantum yields, implying the potential utility of this series PAHs as high-quality organic laser dyes. By using a self-assembly method with the help of epoxy resin, a bottle microlaser based on 3 a was successfully illustrated with a lasing wavelength of 567.8 nm at a threshold of 0.3 mJ/cm². We believe that this work will shed light on the chemical versatility of pentacene and its derivatives in the construction of novel functionalized PAHs.     

A novel approach for simultaneous determination of polycyclic aromatic hydrocarbons by Shpol'skii non-linear variable-angle synchronous fluorescence spectrometry

A new method of combining low-temperature Shpol'skii effect with non-linear variable-angle synchronous fluorescence spectrometry (L-NLVASFS) has been proposed to increase spectral resolution. This coupled method was applied successfully to the simultaneous identification and quantification of some polycyclic aromatic hydrocarbons (PAHs) in mixtures, which cannot be determined by non-linear variable-angle synchronous fluorescence spectrometry at room-temperature (R-NLVASFS). The usefulness of this method is demonstrated by the analyses of synthetic mixtures and several real samples of airborne particulates.     

Rational Design of Star-shaped Molecules with Benzene Core and Naphthalimide Derivatives End Groups as Organic Light-emitting Materials

A series of star-shaped molecules with benzene core and naphthalimides derivatives end groups have been designed to explore their optical,electronic,and charge transport properties as charge transport and/or luminescent materials for organic light-emitting diodes(OLEDs). The frontier molecular orbitals(FMOs) analysis has turned out that the vertical electronic transitions of absorption and emission are characterized as intramolecular charge transfer(ICT). The calculated results show that the optical and electronic properties of star-shaped molecules are affected by the substituent groups in N-position of 1,8-naphthalimide ring. Our results suggest that star-shaped molecules with n-butyl(1),benzene(2),thiophene(3),thiophene S?,S?-dioxide(4),benzo[c][1,2,5]thiadiazole(5),and 2,7a-dihydrobenzo[d]thiazole(6) fragments are expected to be promising candidates for luminescent and electron transport materials for OLEDs. This study should be helpful in further theoretical investigations on such kind of systems and also to the experimental study for charge transport and/or luminescent materials for OLEDs.     

气质联用仪测定电子电气产品中多环芳烃

建立了以甲苯溶剂超声波震荡提取、离心机分离萃取液、气相色谱-质谱联用仪测定电子电气产品中16种多环芳烃组分的方法,萃取条件为:用甲苯溶剂在60℃超声波震荡60 min,外标法定量。各组分的浓度在10～500ng/mL范围内具有良好的线性,线性相关系数r2大于0.994,检出限为0.05～0.30 mg/kg。方法的加标回收率为80%～120%,测定结果的相对标准偏差小于5%。     

Unified Procedure for the Determination of Polycyclic Aromatic Hydrocarbons and Their Nitro Derivatives by Low-Temperature Luminescence

A method was described for determining polycyclic aromatic hydrocarbons (PAHs) and their nitro derivatives (nitro-PAHs) in samples of complex composition using low-temperature luminescence. Fractionation by HPLC was used to separate compounds with similar spectral properties. At the chromatograph inlet, a test sample was purified from weakly retained components additionally preconcentrated on a concentrator cartridge, which was fixed in the injector in place of the sampling loop. Step gradient fractionation was considered, and a table of retention times for PAHs and nitro-PAHs was presented. The the fractional distribution of the analytes was studied. Phosphorescence spectra of some nitro-PAHs were described. The method proposed is comparable in sensitivity to HPLC with the fluorescence detection, but does not require derivatization for determining nitro-PAHs. A table of spectral parameters of analytes suffices for qualitative analysis, as in chromatography–mass spectrometry. However, in distinction to the latter technique, the method described is selective because of the specificity of excitation and emission spectra of each of the analytes.     

Building blocks for N-type molecular and polymeric electronics. Perfluoroalkyl- versus alkyl-functionalized oligothiophenes (nTs; n = 2-6). Systematic synthesis, spectroscopy, electrochemistry, and solid-state organization

The synthesis, comparative physicochemical properties, and solid-state structures of five oligothiophene (nT) series differing in substituent nature and attachment, regiochemistry, and oligothiophene core length (n) are described. These five series include the following 25 compounds: (i) alpha,omega-diperfluorohexyl-nTs 1 (DFH-nTs, n = 2-6), (ii) beta,beta'-diperfluorohexyl-nTs 2 (isoDFH-nTs, n = 2-6), (iii) alpha,omega-dihexyl-nTs 3 (DH-nTs, n = 2-6), (iv) beta,beta'-dihexyl-nTs 4 (isoDH-nTs, n = 2-6), and (v) unsubstituted oligothiophenes 5 (alphanTs, n = 2-6). All new compounds were characterized by elemental analysis, mass spectrometry, and multinuclear NMR spectroscopy. To probe and address quantitatively how the chemistry and regiochemistry of conjugated core substitution affects molecular and solid-state properties, the entire 1-5 series was investigated by differential scanning calorimetry, thermogravimetric analysis, and optical absorption and emission spectroscopies. Single-crystal X-ray diffraction data for several fluorocarbon-substituted oligomers are also presented and compared. The combined analysis of these data indicates that fluorocarbon-substituted nT molecules strongly interact in the condensed state, with unit cell level phase separation between the aromatic core and fluorocarbon chains. Surprisingly, despite these strong intermolecular interactions, high solid-state fluorescence efficiencies are exhibited by the fluorinated derivatives. Insight into the solution molecular geometries and conformational behavior are obtained from analysis of optical and variable-temperature NMR spectra. Finally, cyclic voltammetry data offer a reliable picture of frontier MO energies, which, in combination with DFT computations, provide key information on relationships between oligothiophene substituent effects and electronic response properties.     

Linear and Star-Shaped Extended Di- and Tristyrylbenzenes: Synthesis,Characterization and Optical Response to Acid and Metal Ions

Two linear 1,4-distyrylbenzenes and five star-shaped 1,3,5-tristyrylbenzene derivatives ( L_2a and L_2b , Y₀–Y₃ and Y_NBu ) were synthesized and spectroscopically characterized. The photophysical properties, optical response to acid and metal ions were investigated. Upon backbone extension of linear distyrylbenzenes or the introduction of dibutylanilines, the electronic spectra are redshifted. Incorporation of electron-deficient pyridyl units does not significantly affect the optical properties. Variation of the number of pyridine rings and substitution pattern tune the fluorescence response to acids and metal ions. The novel arenes discriminate Al³⁺, Mn²⁺, Fe³⁺, Fe²⁺, Cd²⁺, Ag⁺ and Hg²⁺.     

Planar,Stair-Stepped,and Twisted: Modulating Structure and Photophysics in Pyrene- and Benzene-Fused N-Heterocyclic Boranes

Because of their rigidity, polycyclic aromatic hydrocarbons (PAHs) have become a significant building block in molecular materials chemistry. Fusion or doping of boron into PAHs is known to improve the optoelectronic properties by reducing the LUMO energy level. Herein, we report a comprehensive study on the syntheses, structures, and photophysical properties of a new class of fused N-heterocyclic boranes (NHBs), pyrene- and benzene-linked in a “Janus-type” fashion ( 2 – 4 , 6 – 9 , and 11 ). Remarkably, these examples of fused NHBs display fluorescent properties, and collectively their emission spans the visible spectrum. The pyrene-fused NHBs all display blue fluorescence, as the excitations are dominated by the pyrene core. In notable contrast, the emission properties of the benzene-fused analogues are highly tunable and are dependent on the electronics of the NHB fragments (i.e., the functional group directly bound to the boron atoms). Pyrene-fused 2 – 4 and 11 represent the only molecules in which the K-region of pyrene is functionalized with NHB units, and while they exhibit distorted (twisted or stair-stepped) pyrene cores, benzene-fused 6 – 9 are planar. The electronic structure and optical properties of these materials were probed by computational studies, including an evaluation of aromaticity, electronic transitions, and molecular orbitals.     

Determination of polycyclic aromatic hydrocarbons (PAHs) in a complex mixture by second-derivative constant-energy synchronous spectrofluorimetry

In this work, the combination of the excellent band narrowing features of derivative spectrometry with constant-energy synchronous fluorescence spectrometry for the simultaneous determination of different polycyclic aromatic hydrocarbons (PAHs) in a mixture of 18 is assessed. This mode of scanning allowed for the identification and quantification of 10 PAHs and the grouping of some of these.     

Synthesis of novel rod-shaped and star-shaped fluorescent phosphane oxides--nonlinear optical properties and photophysical properties

The design of a new class of fluorophores is presented. Some push-pull chromophores (D-pi-A) containing polyphenylethynyl units and a phosphane oxide moiety were efficiently prepared from common intermediates. Straightforward syntheses gave novel one-armed, rod-shaped and three-armed, star-shaped fluorophores. The optical properties of the resulting star-shaped derivatives were evaluated, showed high fluorescence quantum yields, and their excitation induces very efficient charge redistribution. Moreover, thanks to their push-pull character, the molecules exhibited significant second-order NLO properties with good transparency, up to 67x10(-30) esu at 1907 nm, with an absorption lambdamax at 369 nm. The effect of the donor group and of the number of phenylethynyl arms have been studied in this work.     

Determination of airborne polycyclic aromatic hydrocarbons at an airport by gas chromatography-mass spectrometry and evaluation of occupational exposure

The aim of this study was to determine airborne polycyclic aromatic hydrocarbons (PAHs) and biphenyl at an airport by gas chromatography-mass spectrometry and to evaluate occupational exposure by environmental monitoring. A total of 12 samplings were carried out in three areas: (1) a handling area where baggage was unloaded manually from vehicles onto conveyor belts (n=5); (2) the runway with plane and motor vehicle traffic (n=5) and (3) a departure lounge (n=2). PAHs levels were in most cases low. The higher levels found refer to naphthalene (130-13,050 ng/m3) and to its methyl-substitutes 2-methylnaphthalene (64-28,500 ng/m3) and 1-methylnaphthalene (24-35,300 ng/m3), and biphenyl (24-1610 ng/m3). A method was used to quantify twenty-four airborne PAHs, and biphenyl, and to detect a variety of other chemical compounds by means of the deconvolution program AMDIS. After sampling air on quartz filter and PUF and XAD-2 sorbents; extraction with dichloromethane, and concentration and purification on silica cartridges, analyses were carried out by gas chromatography-ion trap mass spectrometry. We used 20 deuterated PAHs to quantify both the 24 native PAHs and biphenyl. The native substances had been subdivided into small groups and in this way, their volatility was adequately reflected by the D-PAH present in each group. The limit of detection was 0.1 ng/m3 for all the PAHs, and a linear range of at least about three-fold the maximum level studied (naphthalene) was obtained both for D-PAHs and the native PAHs. A good recovery pattern was obtained for D-PAHs on quartz filters, PUF and XAD-2.     

Conventional fluorescence spectrometry of polynuclear aromatic hydrocarbons in Shpol'skii matrices at 77 K

A simple fluorimeter assembled from commercial components and its use for the study and application of the Shpol'skii effect on polynuclear aromatic hydrocarbons (PAHs) in n-alkane matrices at 77 K are described. The correlation between the dimensions and geometries of PAHs and their corresponding Shpol'skii solvents is considered. Analytical figures of merit have been evaluated, and the power of the Shpol'skii technique with a conventional fluorimeter in the direct qualitative and quantitative determination of 11 PAHs in mixture is demonstrated. Comparisons with conventional room-temperature fluorescence and laser-excited Shpol'skii spectrometry are also commented upon.     

Hydrogenated tetraazaporphyrins--old but new core-modified phthalocyanine analogues

The synthesis, and spectroscopic and electrochemical properties of hydrogenated tetraazaporphyrins (TAPs), namely tetraazachlorins (TACs), tetraazabacteriochlorins (TABCs) and tetraazaisobacteriochlorins (TAiBCs), have been reviewed. While the first synthesis of this type of hydrogenated aromatic macrocycle was achieved as early as 1958 by Linstead et al. (G. E. Ficken, R. P. Linstead, E. Stephen and M. Whalley, J. Chem. Soc., 1958, 3879), the development of modern synthetic strategies enables us to isolate stable forms of the hydrogenated TAP derivatives. Benzo-, 2,3-naphtho- and 1,2-naphtho-fused derivatives were synthesized extensively, and all structural isomers have been elucidated. The chemical structures have been characterized using a variety of techniques, including mass spectrometry, (1)H and (13)C NMR, X-ray crystallography and IR spectroscopy. The spectroscopic properties (e.g., electronic absorption, magnetic circular dichroism (MCD), and fluorescence) of these compounds differ significantly from those of the original TAPs, or phthalocyanines (Pcs), due to the symmetry-lowering effects of the core aromatic macrocycles. The experimentally observed properties have been rationalized on the basis of electrochemical studies and quantum chemical calculations. As an application of the TAC skeleton, the synthesis and electronic structures of tribenzo TAC (TBTAC)-C(60) conjugates, in which both components are covalently connected directly and thus show remarkable molecular orbital (MO) mixing between the constituting moieties, have also been reviewed.     

Structure-type separation of diesel fuels by solid phase extraction and identification of the two- and three-ring aromatics by capillary GC-mass spectrometry

A simple and effective solid phase extraction (SPE) method using silica gel micro glass columns has been developed for the separation of diesel fuel into groups of aliphatic, and mono-, di- and polyaromatic hydrocarbons. It is based on a stepwise gradient of dichloromethane in n-pentane. The resulting fractions were analyzed by capillary gas chromatography with a flame ionization detector and coupled gas chromatography-mass spectrometry. Commercially available standards, and retention indices and mass spectra were used for identification of individual aromatic compounds. The principal polycyclic aromatic hydrocarbons (PAHs) in diesel fuel are naphthalene, biphenyl, fluorene, phen-anthrene and their alkylated derivatives. Sulfur-containing PAHs are mainly represented by methyl-substituted dibenzo-thiophenes.     

线型和星型平面噻吩类低聚物衍生物分子结构及光电性质研究

运用密度泛函DFT B3LYP／6-31G(d)方法对线型(a)和星型(b)平面噻吩类低聚物衍生物分别进行了几何构型优化,并采用含时密度泛函TD-DFT B3LYP／6-31G(d)方法计算了其紫外吸收光谱．计算结果表明:用TD-DFT．方法计算体系的紫外吸收光谱值与实验数据吻合;通过对噻吩类低聚物衍生物分子几何结构和前线分子轨道能级的分析,并从理论上解释了线型(a)和星型(b)衍生物光谱性质的差异:后者与前者相比较吸收光谱发生红移,这是由于星型结构使其相应HOMO能级升高,电离能(IP)降低,成为很好的电子给体和空穴传输材料．     

Synthesis of C60-fused tetrahydrothiophene derivatives via nucleophilic cycloaddition of thiocyanates

Nucleophilic cycloaddition of thiocyanates 1a-e with C60 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene afforded C60-fused 2-iminotetrahydrothiophene derivatives 2a-e and methanofullerenes 3a-d. The product distributions were highly sensitive to the substrates employed. The 2-iminotetrahydrothiophene derivatives 2a-e could be further manipulated by hydrolysis and acetylation to give 2-oxotetrahydrothiophene derivatives 4a-e and 2-acetamidotetrahydrothiophene derivatives 5a-e. A possible reaction mechanism for the formation of products 2a-e and 3a-d was proposed.