NITROXIDE-MEDIATED FREE RADICAL SYNTHESIS OF MESOGEN-JACKETED LIQUID CRYSTAL POLYMERS*

The first TEMPO-mediated "living" free radical polymerization of liquid crystallinemonomer, 2, 5-bis[(4-methoxyphenyl)oxycarbonyl]styrene(MPCS), was carried out at 130℃ withBPO as an initiator. The molecular weight of the polymer can be varied from rather low values to highvalues while maintaining narrow polydispersity. It was observed that the polymerization of MPCSproceeded much faster than that of styrene. A tentative explanation for this fast polymerization wassuggested.     

Isomeric anthracene diimide polymers

N-type semiconducting polymers are attractive for organic electronics, but desirable electron-deficient units for synthesizing such polymers are still lacking. As a cousin of rylene diimides such as naphthalene diimide (NDI) and perylene diimide (PDI), anthracene diimide (ADI) is a promising candidate; its polymers, however, have not been achieved yet because of synthetic challenges for its polymerizable monomers. Herein, we present ingenious synthesis of two dibromide ADI monomers with dibromination at differently symmetrical positions of the ADI core, which are further employed to construct ADI polymers. More interestingly, the two obtained ADI polymers possess the same main-chain and alkyl-chain structures but different backbone conformations owing to varied linking positions between repeating units. This feature enables their different optoelectronic properties and film-state packing behavior. The ADI polymers offer first examples of conjugated polymer conformational isomers and are highly promising as a new class of n-type semiconductors for various organic electronics applications.

Two anthracene diimide (ADI) polymers with the backbone conformational isomerism, new members of aromatic diimide polymers family, have been synthesized as a class of highly promising n-type semiconductors for organic electronics.     

相转移催化合成对甲氧基肉桂酸-2-乙基己酯的研究

对甲氧基肉桂酸 2 乙基己酯是一种有效的ＵＶＢ防晒剂[1 ,2 ] ,一般采用Ｃｌａｉｓｅｎ Ｓｃｈｍｉｄｔ缩合反应制得[3] ,但由于催化剂ＫＯＨ处于水相 ,对反应物不能充分起到催化作用导致产率较低[4] 。我们利用乙二醇 (ＰＥＧ)为相转移催化剂合成立体专一的反式对甲氧基肉桂酸 2 乙基己酯 ,产率提高到 72 .5 %。合成路线如下 :1　实验部分1 .1　仪器与试剂ＢＩＯ ＲＡＰＦＴ45 0红外光谱仪 ,用液膜法测试 ;Ｂｒｕｒｅｒ ＡＭ 30 0超导核磁共振仪 (溶剂ＤＣ Ｃｌ3) ;ＭＡＴ/44Ｓ ,ＧＣ ＭＳ型色质联用谱仪 ;试剂均为分析纯 ,上海化学试剂…     

有机磷化合物的质谱研究(Ⅶ)——二氮二磷杂环戊烷衍生物的化学电离质谱

本文报道了七种4.5-二氧代-2-硫代-1,3,2,4-二氮二磷杂环戊烷衍生物的化学电离质谱(CIMS,甲烷为反应气),结果表明:CIMS中准分子离子MH~+为基峰离子;MH~+离子易发生失去H_2S,CO,C_3H_6等小分子的裂解,(M+C_2H_5)~+离子存在再断裂。     

反相液相色谱中固定相和流动相对柱相比的贡献

依据柱相比的热力学定义和反相液相色谱中溶质的计量置换保留理论(the stoichiometric dispheement heory of solute for retention，SDT-R)，对反相液相色谱中固定相和流动相性质、温度对柱相比的影响进行了研究。结果表明：固定相的种类和配基的疏水性对柱相比影响较大，而流动相中有机溶剂的种类，特别是脂肪酸作为置换剂时，对柱相比的影响更大，而柱相比受温度的影响较小。此外，通过用27种小分子溶质对柱相比的测定，其logI和Z良好的线性关系，进一步证明柱相比是一个与溶质性质无关的常数。     

Condensed systems based on 4-amino-3-mercapto-1,2,4-triazole

1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazines, hydrazones, and -thio adducts were obtained by reactions of 4-amino-3-mercapto-1,2,4-triazole with -bromoacetophenones, aldehydes, and ,-unsaturated ketones. Conditions that promote the cyclocondensation of the -thio adducts to the previously undescribed 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazepines were found. The chemical and spectral properties of the compounds obtained are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 267–272, February, 1992.     

Total synthesis of crotophorbolone

As a natural diterpenoid, crotophorbolone possesses a challenging trans,trans-5/7/6 framework decorated with six contiguous stereogenic centers and is structurally and biogenetically related to tigliane-type diterpenoids with intriguing bioactivities such as phorbol and prostratin. Based on the convergent strategy, we completed an eighteen-step total synthesis of crotophorbolone starting from (−)-carvone and (+)-dimethyl-2,3-O-isopropylidene-l-tartrate. The key elements of the synthesis involve expedient installation of the six-membered ring and the five-membered ring with multiple functional groups at an early stage, cyclization of the seven-membered ring through alkenylation of the ketone between the five-membered ring and the six-membered ring, functional group-sensitive ring-closing metathesis and final selective introduction of hydroxyls at C₂₀ and C₄.

Convergent total synthesis of crotophorbolone was accomplished in 18 longest linear steps. Observation of unexpected thermodynamic stability of a cis,trans-5/7/6 tricycle would benefit synthetic design of tigliane- and daphnane-related diterpenoids.     

A new method for the quantitation of aflatoxin M1 in urine by high performance liquid chromatography and its application to the etiologic study of hepatoma

A high performance liquid chromatographic (HPLC) method for the analysis of aflatoxin M1 (AFM1) in urine is described. Urine samples were treated with saturated lead acetate and AFM1 was extracted with chloroform. After washing with water to remove impurities the compound was derivatized with trifluoroacetic acid and the AFM1 derivative was analyzed quantitatively by HPLC. The sample pretreatment is simple and more selective. A good line correlation between AFM1 peak height and its concentration was obtained when AFM1 content was in the range of 50-400 pg. The ratio of recovery was 87.42%. Sensitivity is 0.01 ppb. The method is applicable to trace analysis. Results in urine of residents who live in the high/low liver cancer incidence area in Fushui county were the same as that of previous epidemiological investigation.     

Electrochemical Detection of MS2 Phage Using a Bead‐based Immunoassay and a NanoIDA

A microbead based sandwich immunoassay for MS2 bacteriophage was developed using an interdigitated array (IDA) electrode with nanoscale dimensions (220 nm electrode width, 620 nm gap). The IDA was fabricated using an electron beam lithographic lift‐off technique. After an antibody‐assisted capture of MS2 using paramagnetic microbeads, a β‐galactosidase labeled secondary antibody was used to convert p‐aminophenyl‐β‐D ‐galactopyranoside (PAPG) into the redox active p‐aminophenol (PAP). Amperometric detection of PAP with IDA electrodes at +300 and ?200 mV vs. a Ag/AgCl reference electrode was used to measure the result, detecting MS2 concentrations as low as 10 ng/mL.     

Determination of alpha-tocopherol in the Traditional Chinese Medicinal preparation Sea buckthorn oil capsule by non-aqueous reversed phase-HPLC

A non-aqueous reversed phase HPLC was developed for determining alpha-tocopherol in Sea buckthorn oil capsule without the need for saponification. A reversed phase column (Alltima C(18), 4.6 x 250 mm, 5 microm) was used with a mobile phase of methanol-acetonitrile (95 : 5, v/v) and flow rate of 1 ml/min. The contents in capsule were extracted with n-hexane. Detection wavelength was set at 292 nm. Each analysis requires no longer than 20 min. The linearity range for alpha-tocopherol was 9.4-47.0 microg/ml. The detection limit was 0.94 microg/ml. The mean recovery was 95.82 (RSD 2.3%). This method is suitable for quantitative analysis of alpha-tocopherol in Sea buckthorn oil or its Traditional Chinese Medicinal preparation.