Preparation of Partially Hydrogenated 4,6‐Dimethyldibenzothiophenes

The synthesis of three key intermediates of the hydrogenation pathway in the hydrodesulfurization of 4,6‐dimethyldibenzothiophene (4,6‐DM‐DBT; 1 ) is described. The hydrogenated derivatives 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethyl‐1,2,3,4‐tetrahydrodibenzothiophene; 4,6‐DM‐TH‐DBT; 2 ), 1,2,3,4,4a,9b‐hexahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethyl‐1,2,3,4,4a,9b‐hexahydrodibenzothiophene; 4,6‐DM‐HH‐DBT; 3 ), and dodecahydro‐4,6‐dimethyldibenzothiophene (= 4,6‐dimethylperhydrodibenzothiophene; 4,6‐DM‐PH‐DBT; 4 ) were prepared by direct hydrogenation of 1 . The reactions were carried out in continuous and batch reactors by using metal sulfide as well as noble‐metal catalysts. The influence of the reaction conditions on the formation of the products and the distribution of their stereoisomers was studied in detail. The isomers of the main products were isolated and characterized by NMR, GC/MS/MS, and X‐ray crystal‐structure diffractometry.     

Micro/macrotribological properties of several nano‐scale ionic liquid films on modified silicon wafers

Three kinds of alkylimidazolium base room temperature ionic liquids (RTILs) were synthesized and their nano‐scale lubricant films were prepared on modified silicon wafers by dip‐coating method. The thicknesses of these films were measured and their relationship between thickness and solution concentration was obtained. Their surface morphologies were observed and contact angles of water on these films were determined. The adhesions and friction coefficients of these films were detected by contact mode AFM. As comparison, their macrotribological properties were evaluated on a UMT‐2MT tribo‐tester. It was found that, in microscale, 1‐hexyl‐3‐methyl‐imidazolium hexafluorophosphate performed the best tribological properties, while in macroscale, its tribological properties were similar with that of 1‐hexyl‐3‐methyl‐imidazolium tetrafluoroborate and better than that of 1‐hexyl‐3‐methyl‐imidazolium adipate. Copyright © 2009 John Wiley & Sons, Ltd.     

Three‐phase hollow‐fiber liquid‐phase microextraction combined with HPLC–UV for the determination of isothiazolinone biocides in adhesives used for food packaging materials

The present study deals with the development of a liquid microextraction procedure for enhancing the sensitivity of the determination of 2‐methyl‐4‐isothiazolin‐3‐one and 5‐chloro‐2‐methyl‐4‐isothiazolin‐3‐one in adhesives. The procedure involves a three‐phase hollow‐fiber liquid‐phase microextraction using a semipermeable polypropylene membrane, which contained 1‐octanol as the organic phase in the pores of the membrane. The donor and acceptor phases are aqueous acidic and alkaline media, respectively, and the final liquid phase (acceptor) is analyzed by HPLC coupled with diode array detection. The most appropriate conditions were extraction time 20 min, stirring speed 1400 rpm, extraction temperature 50°C. The quantification limits of the method were 0.123 and 0.490 μg/g for 2‐methyl‐4‐isothiazolin‐3‐one and 5‐chloro‐2‐methyl‐4‐isothiazolin‐3‐one, respectively. Three different adhesive samples were successfully analyzed. The procedure was compared to direct analysis using ultra high pressure liquid chromatography coupled with TOF‐MS, where the identification of the compounds and the quantification values were confirmed.     

Polar aspects of intramolecular interactions in 2‐amino‐5‐nitro‐4‐methylpyridines and 2‐amino‐3‐nitro‐4‐methylpyridines

The dipole moments of twelve 2‐N‐substituted amino‐5‐nitro‐4‐methylpyridines ( I‐XII ) and three 2‐N‐substituted amino‐3‐nitro‐4‐methylpyridines ( XIII‐XV ) were determined in benzene. The polar aspects of intramolecular charge‐transfer and intramolecular hydrogen bonding were discussed. The interaction dipole moments, μ_int, were calculated for 2‐N‐alkyl(or aryl)amino‐5‐nitro‐4‐methylpyridines. Increased alkylation of amino nitrogen brought about an intensified push‐pull interaction between the amino and nitro groups. The solvent effects on the dipole moments of 2‐N‐methylamino‐5‐nitro‐4‐methyl‐( I ), 2‐N,N‐dimethylamino‐5‐nitro‐4‐methyl‐ ( II ) and 2‐N‐methylamino‐3‐nitro‐4‐methylpyridines ( XIII ) were different. Specific hydrogen bond solute‐solvent interactions increased the charge‐transfer effect in I , but it did not disrupt the intramolecular hydrogen bond in XIII.     

The Study on Synthesis of Some New 1,2,3‐Triazolylurea and Carbonyl Amide Derivatives

The study on syntheses of some N‐substituted‐N′‐[5‐methyl‐1‐(4‐chlorophenyl)‐1,2,3‐triazol‐4‐yl]‐urea 6a‐e and N‐substituted‐[5‐methyl‐1‐(4‐chlorophenyl)‐1,2,3‐triazol‐4‐yl]carbonyl amide 6f‐l derivatives were reported in this paper. The yielded products 6a‐l were confirmed by elemental analyses, NMR, MS and IR spectra.     

Synthesis and properties of poly(heteroaryleneethynylene)s consisting of electron‐accepting benzothiadiazole/quinoxaline units and electron‐donating alkyl thiophene units

Low‐band‐gap π‐conjugated polymers composed of π‐excessive thiophene and π‐deficient benzothiadiazole and quinoxaline units were prepared in high yields by a polycondensation method using palladium cross‐coupling reactions of alkylthiophene diacetylenes, 4,7‐dibromo‐2,1,3‐benzothiadiazole, and 5,8‐dibromo‐2,3‐dipyridine‐2‐ylquinoxaline. The copolymers were characterized by NMR, IR, UV, gel permeation chromatography, and elemental analysis. High‐molecular‐weight (weight‐average molecular weight up to 82,600 g/mol), thermostable, soluble, and film‐forming materials were obtained. The polymers were photoluminescent in chloroform and showed metallic luster in the solid state. The absorption and emission in solution and in the solid state of the polymers revealed that the polymers generated a π‐stacked structure in the solid state, and the polymer molecules in the film were ordered. Thin films of poly[3‐dodecylthiophen‐2,5‐diylethynylene‐(benzo[1,2,5]thiadiazole‐4,7‐diyl)ethynylene] ( P‐1 ), poly[3,4‐di dodecylthiophen‐2,5‐diylethynylene‐(benzo[1,2,5]thiadiazole‐4,7‐diyl)ethynylene] ( P‐2 ), poly[3‐dodecylthiophene‐2,5‐diylethynylene‐(2,3‐dipyridine‐2‐ylquinoxaline‐5,8‐diyl)ethynylene] ( P‐3 ), and poly[3,4‐didodecylthiophene‐2,5‐diylethynylene‐(2,3‐dipyridine‐2‐ylquinoxaline‐5,8‐diyl)‐ethynylene] ( P‐4 ) exhibited an optical band gap of ～1.85–2.08 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the polymers were determined from electrochemical measurements. In the absorption and emission spectra of these polymers in chloroform/methanol mixtures, all the polymers revealed solvatochromic effects, which were related to the formation of aggregates, as confirmed by temperature‐dependence absorption investigations. The absorption spectra of P‐2 and P‐4 at different temperatures also revealed significant effects of the structure on the molecular interactions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6445–6454, 2005     

Determination of catecholamines and their metabolites in rat urine by ultra‐performance liquid chromatography–tandem mass spectrometry for the study of identifying potential markers for Alzheimer's disease

In order to investigate the potential links between catecholamines (CAs) and Alzheimer's disease (AD), rapid and sensitive ultra‐performance liquid chromatography (UPLC)–tandem mass spectrometry (MS/MS) methods in different ionization modes for the quantification of 14 CAs and their metabolites in rat urine without derivatization or complex sample pre‐treatments were developed. After addition of the internal standard, isoproterenol, the urine samples were extracted by protein precipitation and separated on an Inertsil ODS‐EP column (Shimadzu, Japan) at a flow of 1.0 ml min^?1. Tandem mass spectrometric detection was performed on a 4000Q UPLC–MS/MS in the multiple reaction monitoring mode with turbo ion spray source. Tyrosine, dopamine, noradrenaline, epinephrine, 3‐methoxytyramine, normetanephrine and metanephrine were determined in positive mode, while 3,4‐dihyroxy‐l ‐phenylalanine (DOPA), 3,4‐dihydroxyphenylacetic acid, DL‐3,4‐dihydroxymandelic acid, DL‐3,4‐dihydroxyphenyl glycol, homovanillic acid, DL‐4‐hydroxy‐3‐methoxymandelic acid and 4‐hydroxy‐3‐methoxy‐phenylglycol were determined in negative mode. The methods were examined and were found to be precise and accurate within the linearity range of the assays. The intra‐day and inter‐day precision and accuracy of the analytes were well within acceptance criteria (±15%). The mean extraction recoveries of analytes and internal standard were all more than 60%. The validated methods have been successfully applied to compare CAs profiles in normal and AD rats. The results indicated the urine levels of DL‐3,4‐dihydroxyphenyl glycol and 4‐hydroxy‐3‐methoxy‐phenylglycol in AD rats were significantly higher than those in the normal group, and the other CAs have an opposite performance. These may attribute to the difference of some enzyme activity between rats with AD and normal. Furthermore, this may be helpful in clinical diagnostics and monitor the efficacy of AD treatment. Copyright © 2015 John Wiley & Sons, Ltd.     

Preparation of chiral oxazolinyl‐functionalized β‐cyclodextrin‐bonded stationary phases and their enantioseparation performance in high‐performance liquid chromatography

A simple procedure for the synthesis of three new oxazolinyl‐substituted β‐cyclodextrins (6‐deoxy‐6‐R‐(–)‐4‐phenyl‐4,5‐dihydrooxazolinyl‐β‐cyclodextrin, 6‐deoxy‐6‐S‐(–)‐4‐phenyl‐4,5‐dihydrooxazolinyl‐β‐cyclodextrin, and 6‐deoxy‐6‐S‐(–)‐(4‐pyridin‐1‐ium‐4‐methyl‐benzenesulphonate)‐4,5‐dihy‐drooxazolinyl‐β‐cyclodextrin) and their covalent bonding to silica are reported. The ability of these chiral stationary phase columns for separating compounds is also presented and discussed. Twenty‐eight compounds were examined in the polar‐organic mobile phase mode, and 11 β‐nitroethanols were tested in the reversed‐phase mode. Excellent enantioseparations were achieved for most of the analytes, even for several challenging compounds. The rigid and flexible structures of mono‐substituted chiral groups and the fragments around the rim of the β‐cyclodextrin cavity played an important role in the separation process. Factors such as π–π stacking, dipole–dipole interactions, ion‐pairing, and steric hindrance effects were found to affect the chromatographic performance. Moreover, the buffer composition, and percentages of organic modifiers in the mobile phase, were investigated and compared. The mechanisms involved in the separation were postulated based on the chromatographic data.     

Synthesis and Application of Some Alkali‐Clearable Azo Disperse Dyes Based on Naphthalimide Derivatives

A series of naphthalimide‐based alkali‐clearable azo disperse dyes containing a fluorosulfonyl group was synthesized. 4‐Fluorosulfonylaniline, 4‐fluorosulfonyl‐2‐nitroaniline and 6‐chloro‐4‐fluorosulfonyl‐2‐nitroaniline as the diazo components were prepared from N‐acetylsulfanilyl chloride and were subsequently coupled with 4‐hydroxy‐N‐3‐methoxypropyl‐1, 8‐naphthalimide. The synthesized dyes and their intermediates were characterized by the use of DSC, FTIR, ¹H NMR, ¹³C NMR, Mass spectroscopy and UV‐visible spectroscopic techniques. Spectrophotometric investigations of prepared dyes in different solvents were carried out in order to obtain their absorption maxima, molar extinction coefficients and solvatochromic effects. The obtained dyes were applied to polyester fabric by the HT method and exhibited good leveling, wash and sublimation fastnesses and moderate light fastness. The synthesized dyes showed that incorporated fluorosulfonyl group to these dyes can be converted to the dyes containing a water soluble sulfonate group in the relatively mild alkaline conditions.     

Density‐functional Theory on the Oxidation Potentials and Geometry Parameters of Thioxanthen Derivatives: Theory and Experiment

Abstract

DFT calculations were performed for 1‐fluoro‐4‐hydroxy‐thioxanthen‐9‐one (FHT) and 1‐Hydroxy‐3,4‐dimethyl‐thioxanthen‐9‐one (HDT). The calculated IR spectrum of FHT and HDT were used for the assignment of IR frequencies that were observed in the experimental IR spectrum. The bond lengths and bond angles for FHT and HDT compounds were optimized at B3LYP/6‐31G(d) level of the theory. Cyclic voltammetry of FHT and HDT solutions shows that oxidation electrode potentials of FHT and HDT are 809 and 1214 mV respectively. The electrode potentials were calculated using the solvation energies and the sum of electronic and thermal free energies of FHT and HDT. The theoretical and experimental values of the electrode potentials for the studied compounds are in excellent agreement.     

金属有机骨架衍生 Ni基材料催化烷烃选择氧化

N掺杂碳基纳米材料由于具有高稳定性、良好的导电性、较大的孔体积和比表面积等特点而受到了国内外广泛的关注,在气体吸附、催化、电化学以及燃料电池等许多领域表现出潜在应用价值. N掺杂碳材料的制备主要采用两种方法,即后合成法和原位合成法.后合成法是指采用含 N化合物(如尿素等)对已合成的碳材料进行处理,但所制材料中 N含量往往偏低,且 N活性位不够稳定.要得到 N含量较高且稳定的 N掺杂碳材料常常采用原位合成法,即以富氮前体作为模板,在热解过程中 N原位嵌入碳纳米材料中,因而具有结构稳定, N含量丰富等优点.
　　金属有机骨架(MOFs)材料是一种新型的类沸石类多孔材料,是由金属离子和有机配体通过配位键键合而成的拓扑结构.该类材料具有较高的孔隙率和比表面积以及结构可调控性等特点.通过调节金属中心和配体种类,引入含 N配体,可以得到不同类型的含 N的 MOFs.此外,含 N的 MOFs在一定温度下热解能有效减少 N元素的流失,因此, MOFs是一类优秀的用于制备 N掺杂碳基纳米材料的模板材料.近年来,以含 N的金属有机骨架材料为模板,通过简单热解一步合成 N掺杂碳基纳米催化剂,已成为国内外研究的热点之一.
　　本文在惰性气氛中采用直接热解 Ni基 MOF方法制备了 N掺杂 C包裹的 Ni纳米颗粒,并利用 X射线粉末衍射(PXRD)、N2吸附脱附、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、原子吸收光谱(AAS)、X射线光电子能谱(XPS)等对该复合材料的组成和结构进行了表征.
　　 PXRD测试结果表明,经过热解,催化剂中出现了大量的金属 Ni粒子,说明 Ni-MOF中的 Ni2+离子在热解过程中被原位还原成了 Ni纳米颗粒. N2吸附脱附结果表明,热解前的 Ni-MOF结构中只存在微孔结构,但是热解 Ni@C-N材料中生成了大量的介孔或大孔结构,从而有利于反应底物与催化剂活性位点的接触. SEM结果表明,在较低的温度下热解,催化剂可以保持 MOFs原来的构型,且结构疏松多孔；而在较高的温度下热解,如800oC,将有大量的碳纳米管生成. TEM结果表明,随着热解温度升高,催化剂中 Ni纳米颗粒逐渐增大.从 HRTEM测试结果可以清晰看出,高温热解时有石墨烯结构生成,并且生成的 Ni纳米颗粒原位嵌入了石墨烯结构中,因而有利于 Ni纳米颗粒的分散,从而提高催化剂的活性. XPS结果进一步证明,热解过程中, Ni2+被原位还原成了零价的 Ni纳米粒子,此外, N 1s谱图也进一步证明 N在热解过程中原位嵌入了生成的石墨烯结构中.
　　随后,以乙基苯选择性氧化为模型反应,测试了 Ni@C-N材料的催化活性.结果表明,该材料在烷烃选择氧化反应中表现出很高的催化活性和选择性,尤其是 Ni@C-N-900-8h,在温和的反应条件下,可有效催化一系列饱和烷烃的选择氧化,获得很高的氧化产物收率,且重复利用多次后其活性和选择性没有明显的下降.     

A Three‐Component One‐Pot Synthesis of Functionalized 5,5‐Dicyanocyclopenta‐1,3‐dienes from Arylidene­malononitriles,Activated Acetylenes,and KCN or KSCN

The reaction of dialkyl acetylenedicarboxylates with arylidenemalononitriles in the presence of KSCN in MeCN led to a mixture of dialkyl (3E)‐4‐aryl‐3‐(arylideneamino)‐5,5‐dicyanocyclopenta‐1,3‐diene‐1,2‐dicarboxylates and dialkyl 4‐aryl‐5‐cyanothiophene‐2,3‐dicarboxylates. When these reactions were performed in the presence of KCN, only the functionalized 5,5‐dicyanocyclopenta‐1,3‐dienes were obtained.     

Sensitive determination of sulfonamides in environmental water by capillary electrophoresis coupled with both silvering detection window and in‐capillary optical fiber light‐emitting diode‐induced fluorescence detector

A new detector, silvering detection window and in‐capillary optical fiber light‐emitting diode‐induced fluorescence detector (SDW‐ICOF‐LED‐IFD), is introduced for capillary electrophoresis (CE). The strategy of the work was that half surface of the detection window was coated with silver mirror, which could reflect the undetected fluorescence to the photomultiplier tube to be detected, consequently enhancing the detection sensitivity. Sulfonamides (SAs) are important antibiotics that achieved great applications in many fields. However, they pose a serious threat on the environment and human health when they enter into the environment. The SDW‐ICOF‐LED‐IFD‐CE system was used to determine fluorescein isothiocyanate (FITC)‐labeled sulfadoxine (SDM), sulfaguanidine (SGD) and sulfamonomethoxine sodium (SMM‐Na) in environmental water. The detection results obtained by the SDW‐ICOF‐LED‐IFD‐CE system were compared to those acquired by the CE with in‐capillary optical fiber light‐emitting diode‐induced fluorescence detection (ICOF‐LED‐IFD‐CE). The limits of detection (LODs) of SDW‐ICOF‐LED‐IFD‐CE and ICOF‐LED‐IFD‐CE were 1.0–2.0 nM and 2.5–7.7 nM (S/N = 3), respectively. The intraday (n = 6) and interday (n = 6) precision of migration time and corresponding peak area for both types of CE were all less than 0.86% and 3.68%, respectively. The accuracy of the proposed method was judged by employing standard addition method, and recoveries obtained were in the range of 92.5–102.9%. The results indicated that the sensitivity of the SDW‐ICOF‐LED‐IFD‐CE system was improved, and that its reproducibility and accuracy were satisfactory. It was successfully applied to analyze SAs in environmental water.     

Protein‐Based Capacitive Biosensors: a New Tool for Structure‐Activity Relationship Studies

The present work reports a new application of a protein‐based capacitive biosensor as an in vitro assay for the selectivity study of the bacterial periplasmic protein MerP and four MerP variants. The modified MerP proteins were produced by site‐directed mutagenesis of the heavy metal associated motif (HMA). The MerP and modified MerPs selectivity for copper, zinc, cadmium and mercury bivalent ions were investigated and compared. The variations in the proteins affinity were related to the primary structure of the HMA motifs. Key amino acids for copper coordination of metalloproteins that contain the metal binding sequence Gly‐Met‐Thr‐Cys‐xxx‐xxx‐Cys were identified. The results brought insights valid for Menkes and Wilson ATPases. The protein‐based capacitive biosensors were a simple and useful tool for studying structure‐activity relationships of proteins.     

Crystal Structures and Redox Responses Coupled with Ion Recognition of p‐Benzoquinone‐ and Hydroquinone‐Fused [18]crown‐6

The crystal structures and redox properties of p‐benzoquinone (BQ)‐fused [18]crown‐6 1 and bis‐BQ‐fused [18]crown‐6 2 were examined. The anion radicals of these BQ molecules were stabilized by addition of metal ions, through effective electrostatic interactions between the negatively charged BQ moiety and positively charged ion‐capturing [18]crown‐6 unit. The electrostatic interactions and solvation energy played important roles in determining the magnitudes of anodic redox shifts in the reduction potentials. Regular π‐stacking of BQ units and regular arrays of [18]crown‐6 units were observed in crystal 2 , in which one‐dimensional π‐electron columns were separated by ionic channels. The hydroquinone‐fused [18]crown‐6 molecule 3 and a new BQ‐ and phenol‐fused [18]crown‐6 derivative 4 were obtained as single crystals. The molecular conformations of [18]crown‐6 in crystal 3 and hydrated crystal 3 ?H₂O were different from each other.     

The suzuki–heck polymerization as a tool for the straightforward obtainment of poly(fluorenylene‐vinylene) sensitizers for dye‐sensitized solar cells

This article describes the synthesis and properties of the first poly(arylene‐vinylene)‐based sensitizers for application in dye‐sensitized solar cells (DSSC). The polymers were prepared by the Suzuki–Heck copolymerization of potassium vinyltrifluoroborate (PVTB) with a mixture of dibromoaryl comonomers designed to obtain macromolecules able to bind onto the photoelectrode by means of carboxyphenylene units. The copolymerization reactions were carried out in the presence of an excess of PVTB to lower the molecular weights of the polymers, which were obtained as soluble materials. The polymers poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene] ( P1 ), poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene‐co‐(4,7‐benzothiadiazolylene)‐vinylene] ( P2 ), and poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene‐co‐2,5‐thienylene‐vinylene] ( P3 ) were used in DSSC devices, obtaining conversion efficiencies up to 0.88% ( P3 ). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Piezoelectric Quartz Crystal Anti‐Protein Immunosensors Based on Immobilized Fullerene C60‐Proteins

Various fullerene C60‐proteins such as C60‐myoglobin (C60‐Mb), C60‐hemoglobin (C60‐Hb) and C60‐gliadin, coated piezoelectric quartz crystals were prepared and applied in piezoelectric quartz crystal immunosensors for protein‐antibodies such as anti‐myoglobin (Anti‐Mb), anti‐hemoglobin (Anti‐Hb) and anti‐gliadin respectively. The immobilizations of myoglobin, hemoglobin and gliadin onto Fullerene C60 were studied with a C60‐coated piezoelectric crystal detection system, respectively. The partially irreversible frequency responses for theses proteins were observed by a desorption study, implying that C60 can strongly adsorb these proteins. Thus, immobilized C60‐Mb, C60‐Hb and C60‐gliadin coating materials were successfully prepared and identified with FTIR spectrometry. The C60‐Mb, C60‐Hb and C60‐gliadin coated piezoelectric (PZ) quartz crystal immunosensors with homemade computer interfaces for signal acquisition and data processing were developed and applied for detection of Anti‐Mb, Anti‐Hb and anti‐gliadin respectively. The C60‐protein coated PZ immunosensors for Anti‐Mb, Anti‐Hb and antigliadin exhibited linear frequency responses to the concentrations of theses anti‐proteins with sensitivities of 1.43 × 10³, 2.59 × 10³ and 8.05 × 10³ Hz/(mg/mL) respectively. The detection limits of these PZ‐immunosensors were 4.36 × 10^?3, 3.23 × 10^?3 and 1.98 × 10^?3 mg/mL for Anti‐Mb, Anti‐Hb and anti‐gliadin respectively. Effects of pH and temperature on the frequency responses of the anti‐protein PZ‐immunosensors were also investigated. The optimum pH of these anti‐proteins and the optimum temperature for the PZ‐immunosensors were observed at pH = 7 and around 30 °C respectively. The interferences of various common species in human blood, e.g., cysteine, tyrosine, urea, glucose, ascorbic acid and metal ions, to these anti‐protein PZ‐immunosensors were also investigated respectively. These species showed nearly no interference or quite small interference with the anti‐protein PZ‐immunosensors. The reproducibility and lifetime of these immobilized C60‐protein coated PZ crystal immunosensors were also investigated and discussed.     

Synthesis and properties of functional aliphatic polycarbonates

Two, functional, cyclic carbonate monomers, 5‐methyl‐5‐methoxycarbonyl‐1,3‐dioxan‐2‐one and 5‐methyl‐5‐ethoxy carbonyl‐1,3‐dioxan‐2‐one, were synthesized starting from 2,2‐bis(hydroxymethyl) propionic acid. The ring‐opening polymerization of the cyclic carbonate monomers in bulk with stannous 2‐ethylhexanoate as a catalyst under different conditions was examined. The results showed that the yield and molecular weight of polycarbonates were significantly influenced by the reaction conditions. The polycarbonates obtained were characterized by IR, ¹H NMR, and differential scanning calorimetry. Their molecular weight was measured by gel permeation chromatography. The in vitro biodegradation and controlled drug‐release properties of the polycarbonates were also investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 4001–4006, 2003     

Investigation of free and conjugated seleno‐amino acids in wheat bran by hydrophilic interaction liquid chromatography with tandem mass spectrometry

An analytical method for determining seleno‐methionine, methyl‐seleno‐cysteine, and seleno‐cystine in wheat bran was developed and validated. Four different extraction procedures were evaluated to simultaneously extract endogenous free and conjugated seleno‐amino acids in wheat bran in order to select the best extraction protocol in terms of seleno amino acid quantitation. The extracted samples were subjected to a clean‐up by a reversed phase/strong cation exchange solid‐phase extraction and analyzed by chiral hydrophilic interaction liquid chromatography‐tandem mass spectrometry. The optimized extraction protocol was employed to validate the methodology. Process efficiency ranged from 58 to 112% and trueness from 73 to 98%. Limit of detection and limit of quantification were lower than 1 ng/g. Four wheat bran samples were analyzed for both total Se and single seleno‐amino acids determination. The results showed that Se‐ seleno‐methyl‐l selenocysteine was the major seleno‐amino acid in wheat bran while seleno‐methionine and seleno‐cysteine were both minor species.     

Regioselective grignard metathesis reaction of 2,5‐dibromo‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene and kumada coupling polymerization

2,5‐Dibromo‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene ( DBPyTh ) was synthesized by the Suzuki coupling reaction between two aromatic compounds followed by the bromination. The Grignard metathesis reaction of DBPyTh with isopropylmagnesium chloride proceeded in 85% conversion and the regioselective halogen–metal exchange at the 2‐position was confirmed. Namely, 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene and 2‐bromo‐5‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene were generated in 90:10 molar ratio. Subsequently, the Kumada coupling polymerization was carried out using 1,3‐bis(diphenylphosphinopropane)nickel(II) dichloride to obtain poly(3‐(6′‐hexylpyridine‐2′‐yl)thiophene) ( PolyPyTh ). The polymer molecular weight could be roughly controlled by the catalyst concentration and the molecular weight distribution ranged from 1.25 to 1.80. The gas chromatograph analysis indicated that 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene was preferentially polymerized in 90% conversion and the percentage of the head‐to‐tail content (regioregularity) was calculated to be 96%. The matrix‐assisted laser desorption/ionization time‐of‐fright mass spectrum indicated that both polymer chain ends were substituted with the hydrogen atom. The absorption maxima of polymer in CHCl₃ and thin film were observed at 447 and 457 nm, respectively, which were blue‐shifted compared with poly(3‐(4′‐octylphenyl)thiophene). From the CV measurement of the polymer thin film, highest occupied molecular orbital (HOMO) (?5.31 eV) and lowest unoccupied molecular orbital (LUMO) (?3.76 eV) energy levels were calculated from the oxidation and reduction onset potentials, respectively, and the electrochemical band gap energy was determined to be 1.62 eV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011