Electrosynthesis of highly conducting poly(1,5-dihydroxynaphthalene) in BF3·Et2O

Direct anodic oxidation of 1,5-dihydroxynaphthalene (DHN), an important derivative of naphthalene, led to the formation of high-quality semiconducting poly(1,5-dihydroxynaphthalene) (PDHN) on stainless steel sheets in boron trifluoride diethyl etherate (BFEE). The onset oxidation potential of DHN in this medium was measured to be only 0.78 V vs. SCE, which was lower than that determined in traditional acetonitrile containing 0.1 mol/L tetrabutylammonium tetrafluoroborate (0.98 V vs. SCE). As-formed PDHN films showed good redox activity and stability, together with interesting electrochromic property from brown (doped) to yellow-green (dedoped). Structural characterization, including FTIR, ¹H NMR, and quantum chemistry calculations, indicated that the polymerization of DHN probably occurred at C₄ and C₈ positions. Moreover, thermal analysis revealed that PDHN displayed better thermal stability than that synthesized by chemical method. The fluorescence spectral studies, together with the electrical tests, showed that PDHN was a good blue light-emitter (fluorescence quantum yield higher than 0.1) with an electrical conductivity of as high as 0.46 S/cm.     

Direct electrosynthesis and characterization of a new soluble polyfluorene derivative containing carboxyl group in boron trifluoride diethyl etherate

High-quality poly(fluorene-9-acetic acid) (PFAA), a new soluble polyfluorene derivative, was synthesized electrochemically by direct anodic oxidation of fluorene-9-acetic acid (FAA) in boron trifluoride diethyl etherate (BFEE) containing a certain amount of trifluoroacetic acid (TFA). This electrolyte enables facile anodic oxidation of FAA monomer at lower potential (1.05 V vs. SCE). PFAA films with conductivity of 0.53 S cm⁻¹ obtained from this medium showed better redox activity and thermal stability in relation to unsoluble poly(fluorene-9-carboxylic acid). Fluorescent spectral studies indicate that PFAA film with high fluorescence quantum yields and photochemical stability is a good blue-light emitter. The structure and morphology of the polymer were studied by UV–vis, FT-IR, ¹H NMR spectra and scanning electron microscopy, respectively.     

磷酸硼固体酸催化合成邻苯二甲酸二乙酯的性能研究

以邻苯二甲酸酐和无水乙醇为原料,固体磷酸硼为催化剂,在醇酐比为4：1,催化剂用量为苯酐用量的20．3％,反应时间8h,反应温度80℃条件下合成邻苯二甲酸二乙酯（DEP）,探讨了影响催化剂催化效果的各个因素。实验表明,催化剂最佳的制备条件为：磷酸、硼酸和硫酸的摩尔比为1：1：1,焙烧温度为300℃,焙烧时间为3．5h。DEP最高产率可达75％。     

Characterization and biodegradability of polyester bioplastic-based green renewable composites from agricultural residues

The biodegradability, morphology, and mechanical properties of composite materials consisting of acrylic acid-grafted poly(butylene succinate adipate) (PBSA-g-AA) and agricultural residues (rice husk, RH) were evaluated. Composites containing acrylic acid-grafted PBSA (PBSA-g-AA/RH) exhibited noticeably superior mechanical properties compared with those of PBSA/RH due to greater compatibility with RH. The dispersion of RH in the PBSA-g-AA matrix was highly homogeneous as a result of ester formation, and the consequent creation of branched and cross-linked macromolecules, between the carboxyl groups of PBSA-g-AA and hydroxyl groups in RH. Each composite was subject to biodegradation tests in an Azospirillum brasilense BCRC 12270 liquid culture medium. The bacterium completely degraded both the PBSA and the PBSA-g-AA/RH composite films. Morphological observations indicated severe disruption of the film structure after 20-40 days of incubation. The PBSA-g-AA/RH (20 wt%) films were not only more biodegradable than those made of PBSA but also exhibited lower molecular weight and intrinsic viscosity, implying a strong connection between these characteristics and biodegradability.     

Study on the Synthesis and Biodegradation of Aliphatic Polyester

With the increasing use of one-off plastic products, the environmental pollution resulted from the plastic waste has become more and more serious. So many scientists have focused their attention on developing biodegradable polymers to substitute the traditional unbiodegradable polymers in the manufacture of disposable products. Thus the plastic waste can be treated by landfill or composting technique. It has been found that aliphatic polyesters possess better biodegradability compared with oth…     

1,4-二氢-2,6-二甲基-3,5-吡啶二甲酸二乙酯的合成

用季铵盐作相转移催化剂,在较温和的条件下使乙酰乙酸乙酯与甲醛和氨缩合,合成了1,4－二氢－2,6－二甲基－3,5－吡啶二甲酸二乙酯（DHP）,研究了多种反应因素对产物的影响,提出了合成DHP的最佳工艺条件,投料摩尔比mol乙酰乙酸乙酯：mol六次甲基四胺＝2：1.5,20％（wt％）乙醇水溶液作溶剂,反应温度55℃,反应时间45min,产品收率达88％。     

反相流动注射-分光光度法测定水中痕量余氯的研究

研究并建立了测定水中痕量总余氯和游离余氯的Ｎ,Ｎ－二乙基－１,４－苯二胺（ＤＰＤ）反相流动注射分光光度法。将ＤＰＤ溶液和ＨＰＯ４＾２－－Ｈ２ＰＯ４＾－缓冲溶液（ｐＨ６．７）的混合液注入试样载流中,再与ＫＩ溶液或硫代乙酰胺溶液流混合,在５１０ｎｍ处对反应形成的红色半醌式化合物进行分光光度测定。     

Nanosized barium carbonate particles stabilized by cetyltrimethylammonium bromide at the water/hexamethylene interface

Nanoparticles of barium carbonate (BaCO₃) have been synthesized in situ from barium chloride by the slow release of carbon dioxide by alkaline hydrolysis of diethyl carbonate, and stabilized by cetyltrimethylammonium bromide (CTAB) at the water/hexamethylene interface. Transmission electron microscopy, Fourier transform infrared spectroscopy and X‐ray powder diffractometry were used to characterize the products. The results indicate that spherical BaCO₃ nanoparticles are obtained with poor crystallinity and diameters ranging from 30 to 300 nm. The possible formation mechanism of the nanoparticles at the interface is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

甲醇-三氟化硼乙醚混合质子电解质

甲醇和三氟化硼乙醚(BFEE)本身离子电导率很低,向甲醇溶液中加入少量BFEE可以形成良好的质子电解质溶液.随着甲醇中BFEE浓度的变化,溶液的离子电导率具有最大值,达20mS/cm.红外光谱和1HNMR研究表明混合电解质中的主要导电离子为MeOH2+和MeOBF3-.     

A new polyketide purpurogenic acid: the activated production of polyketides by the diethyl sulphate mutagenesis of marine-derived Penicillium purpurogenum G59

A new polyketide, purpurogenic acid (1), and two known polyketides, (-)-mitorubrin (2) and (-)-mitorubrinol (3), were isolated from a fungal mutant derived from the diethyl sulphate (DES) mutagenesis of marine-derived Penicillium purpurogenum G59. The planar structure of new 1 was elucidated by spectroscopic methods and the absolute configuration was assigned on the basis of [α]_D and CD data. In our preliminary MTT assay, 1 inhibited human cancer K562, HL-60, HeLa and BGC-823 cells with the inhibition rates of 52.7, 78.8, 38.4 and 35.3% at the 100 μg/mL, respectively.