Non-monotonic exposure dependence of the pretilt angle and surface polarity of the photo-orientant F-PVCN

We report on the first observation of a non-monotonic UV exposure dependence of the pretilt angle of a liquid crystal on a photoaligning surface. We found this non-monotonic dependence on fluorinated poly(vinyl cinnamate) (PVCN-F) surface while non-fluorinated PVCN revealed a monotonic decrease of the pretilt angle with exposure. These dependences correlate with light-induced changes of the polarity of PVCN-F and PVCN surfaces. The obtained data point to an important role of the surface polarity and the light-induced changes in mechanisms of pretilt angle generation on photoaligning materials.     

Synthesis and Fluorescent Behaviors of Polymers Bearing Stilbene Derivatives

A series of novel acrylate monomers bearing stilbene segments with D-π -A structure, 4-methacrylate-4′-nitro stilbene (NS), 4-(6-methacrylate)hexyl-4′-nitro stilbene (HNS) and 4-(6-methacrylate)hexyl-2,3-dimethoxy-4′-nitro stilbene (DMHNS), were synthesized by the Witting reaction and polymerized by free radical polymerization. These stilbene-containing monomers and polymers were fully characterized, and their fluorescent properties in solution and solid state were also investigated. The emission band of monomers and corresponding polymers in solution also showed a remarkable effect with increasing polarity of the solvent. More importantly, the fluorescence emission could be adjusted from green to orange and even red regions by forming donor-π -acceptor (D-π -A) construction.     

The synthesis of non‐symmetrical stilbene analogs of trans‐resveratrol using the same Pd catalyst in a sequential double‐Heck arylation of ethylene

We have developed a sequential and selective Pd‐catalyzed double‐Heck arylation of ethylene that results in non‐symmetrical nitro‐stilbene analogs of trans‐resveratrol at excellent yields. A catalytic system consisting of Pd(OAc)₂ and P(o‐tolyl)₃ permitted us to carry out the two consecutive Heck arylations without losing activity from the first to the second Heck reaction. After the first Heck arylation of ethylene, no isolation or additional catalyst loading is required for the second Heck arylation reaction. This protocol was applied to the synthesis of methylated trans‐resveratrol, which was obtained at a 65% overall yield. Copyright © 2011 John Wiley & Sons, Ltd.     

Samarium Diiodide Mediated Coupling of Aroyl Chlorides

α, α'‐Stilbenediol dibenzoate compounds were synthesized in moderate to good yields through the coupling of aroyl chloride promoted by samarium diiodide under mild conditions.     

Hydroxylamine synthesis by oxygen insertion into ReNH2 bond via Baeyer–Villiger oxidation: a Theoretical study

A novel scheme has been proposed by computational methods (B3LYP and CCSD(T)) to produce hydroxylamine under normal experimental conditions using [O₃Re‐(NH₂)] and H₂O₂ under basic conditions. This particular reaction may proceed similar to Baeyer–Villiger oxidation and μ‐peroxo type pathways to insert oxygen into the Re?NH₂ bond to yield NH₂OH; nevertheless, Baeyer–Villiger type oxidation is seems to be more viable. The calculated energy barriers further revealed that the introduction of different solvent medium does not affect significantly the energies of intermediates and transition state molecules. The calculated Gibbs free energies show that this reaction is perhaps viable experimentally to produce NH₂OH from the our choice of reagents. Copyright © 2015 John Wiley & Sons, Ltd.     

水相中3,5-二芳基异噁唑衍生物的微波辐射合成

微波辐射下,以芳香醛和芳香酮为起始原料合成2,4,6-三芳基吡喃盐,在NaOH水溶液中与盐酸羟胺发生开环、缩环和脱苯甲酰基反应,一步生成3,5-二芳基异噁唑衍生物。考察了微波辐射功率和辐射时间对目标产物收率的影响,2,4,6-三芳基吡喃盐与盐酸羟胺反应生成3,5-二芳基异噁唑衍生物的最佳微波辐射功率为600W,辐射时间为8min,最大收率为83%。该法不仅避免了使用高氯酸造成的环境污染,而且以水作为反应介质,使后处理简便。该工艺具有操作安全、反应条件温和和产率高等优点,是一种环境友好的合成工艺。产物经元素分析、1HNMR和MS测试技术表征了其结构。     

Synthesis and Spectral Tuning of Novel Triphenylamine-Based Derivatives Containing Electron Donor-Acceptor Groups

This paper presents the investigation of tuning the color and photoluminescence of a range of triphenylamine‐ based derivatives with various substituent groups. The ultraviolet/visible absorption and fluorescence spectroscopy of the derivatives showed remarkable difference. The molecular geometry optimization demonstrated that the properties of the ground state and the excited state of the compounds have a close relationship with the substituent groups. Therefore, it is possible to tune the color and photoluminescence of the derivatives at molecular level. The cyclic voltammograms of these compounds were detected in methylene chloride at various scan rates. The thermal stabilities of the compounds were analyzed with the different scanning calorimetry and the thermogravimetry.     

香豆素羟胺在糠醛类化合物荧光定量分析中的应用

糠醛类化合物在食品工业中是一种独特的风味物质,但在人体积蓄过多时具有一定的致癌作用,因此在食品工业和环境检测中糠醛类化合物的定量分析十分重要。本实验以香豆素羟胺作为荧光标记物,通过硝酮化反应对糠醛类化合物进行荧光衍生,并结合液相色谱-荧光检测法准确测定了奶粉中糠醛、5-甲基糠醛和5-羟甲基糠醛的含量,具有选择性高、线性范围宽、检测限低等优点。本实验将最新的科学研究成果转换为应用化学专业“综合化学实验”课程中的一个研究设计性实验,力图通过全方位的实验操作和训练,使学生充分了解荧光与分子结构的关系、荧光衍生试剂的设计与选择、现代分析仪器的检测原理及应用范围;通过对仪器测试条件和衍生反应条件进行优化,学会实验设计的优化方法,了解科学研究的基本流程,从而激发学生对科学研究的兴趣,提高学生的动手操作能力,培养其勤于思考的科学精神,全面提升其创新能力和综合素质。     

The interaction of 2-(4-acetylphenylamino)-3-piperidino-1,4-naphthoquinone with hydroxylamine and hydrazines

With acid catalysts 2-(4-acetylphenylamino)-3-piperidino-1,4-naphthoquinone reacts with hydroxylamine and aryl hydrazines exclusively at the carbonyl group of its side chain. The products corresponding to the condensation at the naphthoquinone C=O group could not be detected.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1086–1088, June, 1994.