High-Performance Dipolar Organic Dyes with an Electron-Deficient Diphenylquinoxaline Moiety in the π-Conjugation Framework for Dye-Sensitized Solar Cells

We report here the synthesis and electrochemical and photophysical properties of a series of easily prepared dipolar organic dyes and their application in dye-sensitized solar cells (DSSCs). For the six organic dyes, the molecular structures comprised a triphenylamine group as an electron donor, a cyanoacrylic acid as an electron acceptor, and an electron-deficient diphenylquinoxaline moiety integrated in the π-conjugated spacer between the electron donor and acceptor moieties. The incorporation of the electron-deficient diphenylquinoxaline moiety effectively reduces the energy gap of the dyes and broadly extends the spectral coverage. DSSCs based on dye 6 produced the best overall cell performance of 7.35?%, which translates to approximately 79?% of the intrinsic efficiency of the DSSCs based on the standard N719 dye under identical experimental conditions. The high performance of DSSCs based on dye 6 among the six dyes explored is attributed to the combined effects of high dye loading on a TiO(2) surface, rapid dye regeneration, and effective retardation of charge recombination.     

Synthesis and spectroscopic studies of 4-Formyl-4′-N,N-dimethylamino-1,1′-biphenyl: The unusual red edge effect and efficient laser generation

The synthesis and photophysics of 4-formyl-4-N,N-dimethylamino-1,1-biphenyl are reported. The emission spectrum in various solvent polarities demonstrates solvatochromism, indicating that the fluorescence originates from an electronically excited species with a strong charge transfer character. The change in [ _max(absorption) – _max(emission)] varies from 1500 cm^–1 inn-heptane to as much as 7500 cm^–1 in acetonitrile. In protic solvents, the unusual excitation energy-dependent steady-state emission (red edge effect), resulting from solvent dielectric relaxation, was observed in media with a low viscosity. The large Stokes-shifted and high-yield fluorescence led to the observation of the efficient lasing action. The frequency tunability of the laser output is strongly solvent dependent, generating a new charge transfer laser dye in the blue-green region.     

A novel enantioselective alkylation and its application to the synthesis of an anticancer agent

A novel enantioselective alkylation of double benzylic substrates with secondary electrophiles is reported. A simple norephedrine-based chiral ligand was synthesized that gives alkylation product in 95% yield and 95% ee. A unique water effect on the enantioselectivity was unveiled. Good to excellent ee values were obtained with a number of double benzylic substrates and secondary electrophiles. This novel reaction has been applied to the synthesis of a promising anticancer agent.     

Microstructural and magnetic studies of L10 FePt–SiO2 nano-composite thin film with columnar structure for perpendicular magnetic recording

(Fe₅₀Pt₅₀)_100−x-(SiO₂)_x films (x=0–30 vol%) were grown on a textured Pt(0 0 1)/CrRu(0 0 2) bilayer at 420 °C using glass substrates. FePt(0 0 1) preferred orientation was obtained in the films. Interconnected microstructure with an average grain size of about 30 nm is observed in the binary FePt film. As SiO₂ is incorporated, it precipitates as particles are dispersed at FePt grain boundaries. When the content of SiO₂ is increased to 13 vol%, columnar FePt with (0 0 1) texture separated by SiO₂ is attained. The FePt columns have a length/radius ratio of 2:1. Additionally, the mean grain size is reduced to about 13 nm. The development of this well-isolated columnar structure leads to an enhancement in coercivity by about 44% from 210 to 315 kA/m. As the SiO₂ content exceeds 20 vol%, a significant ordering reduction is found accompanied by a transformation of preferred orientation from (0 0 1) to (2 0 0) and the columnar structure disappears, resulting in a drastic degradation in magnetism. The results of our study suggest that isolated columnar, grain refined, (0 0 1)-textured FePt film can be achieved via the fine control of SiO₂ content. This may provide useful information for the design of FePt perpendicular recording media.     

Rumphellatin A, the first chloride-containing caryophyllane-type norsesquiterpenoid from Rumphella antipathies

A novel chloride-containing 14C norsesquiterpenoid, rumphellatin A (1), was isolated from the Formosan gorgonian coral Rumphella antipathies. The structure of metabolite 1 was determined on the basis of spectral data analysis and the configuration of 1 was further supported by molecular mechanics calculations. Rumphellatin A (1) showed activity against Gram-negative bacteria.     

Quantification and Optimization of Ethanolic Extract Containing the Bioactive Flavonoids from Millettia pulchra Radix

Millettia pulchra is traditionally used for treating diseases, including joint pain, fever, anemia, and allergies. It is also a potential resource of natural flavonoid derivatives, which represents major constituents of this plant. This study aimed to isolate the major compounds from M. pulchra radix, develop and validate the HPLC-PDA method to determine their contents, and optimize its extraction. Four major flavonoid derivatives (karanjin, lanceolatin B, 2”,2”-dimethylpyrano-[5″,6″:7,8]-flavone, and pongamol) were isolated using silica gel column chromatography, crystallization techniques in large amounts with high purities (>95%). A simple, accurate high-performance liquid chromatography–photodiode array (HPLC–PDA) detection method has been developed and validated with significantly statistical impacts according to International Conference on Harmonization (ICH) guidelines. The Response Surface Methodology (RSM), Artificial Neural Network (ANN) models were employed to predictive performance and optimization of the extraction process. The optimized conditions for the extraction of major flavonoids were: extraction time (twice), solvent/material ratio (9.5), and ethanol concentration (72.5%). Our research suggests an effective method, which will be helpful for quality control in the pharmaceutical development of this species.     

A convenient new procedure for converting primary amides into nitriles

An operationally simple and high-yielding procedure has been developed for the conversion of primary amides to the corresponding nitriles, using ethyl dichlorophosphate/DBU as the mild dehydrating agent.     

分子体系的高压化学反应

在高压(一万到百万大气压)下物质的组成、结构、化学反应都可以发生前所未知的巨大变化。运用高压合成目标产物,表征高压下的物质结构与反应过程是高压化学研究的主要问题。一般而言,高压下不饱和化合物倾向于聚合形成高密度饱和共价键体系;反应中分子与原子扩散严重受限,常形成亚稳态化合物;反应物的空间晶体结构、官能团性质、反应体系的温度、静水压效果都对反应有显著影响。对高压下分子化学反应的研究需要综合运用晶体学、谱学、化学等实验手段和热力学、动力学等方面的理论计算相互验证,进而建立理论,深入极端条件化学的星辰大海。     

聚氧化乙烯/高岭石聚合物电解质的制备与表征

通过尿素对高岭石的插层及随后的超声脱除处理,制备了一种片层剥离的高岭石粉体,并将这种剥离高岭石与聚氧化乙烯/高氯酸锂(PEO/LiClO_4)体系复合,制备出PEO/高岭石复合物.采用X射线衍射仪、红外光谱仪、扫描电子显微镜、透射电子显微镜、扫描量热仪、电化学工作站和万能材料试验机进行结构表征和性能测试.结果表明,尿素在高岭石层间的插层和脱除引起了高岭石片层的剥离,片层厚度小于50 nm.剥离高岭石在PEO/LiClO_4体系中与PEO形成了强烈的氢键作用,促进了PEO结晶度的降低,进而提高复合物的离子电导率.含有20 wt%剥离高岭石填料的PEO/高岭石复合物的离子电导率达到6.0×10~(-5) S/cm,与未复合的PEO/LiClO_4相比,提高了一个数量级.复合物制备过程中的烘干温度对PEO的结晶度会产生一定的影响,95°C下的烘干处理能得到结晶度较低,离子电导率较高的复合物.此外,剥离高岭石的添加显著提高了聚合物的杨氏模量和拉伸强度,与未复合的PEO/LiClO_4相比,杨氏模量和拉伸强度最大提高了256%和121%.     

Recent advances of transformable nanoparticles for theranostics

We summary recent advances of transformable NPs for nanomedicine. In this review, the transformation of NPs is divided into three groups including changes in size, surface charge and morphology, which is induced by internal stimuli, such as pH, enzyme, receptor or external stimuli, such as light, temperature.