Improving FLC Properties. Simplicity, Planarity, and Rigidity in New Chiral Oxazoline Derivatives
摘要:
In an attempt to develop new dopants for improved ferroelectric properties in liquid crystals, aryloxazolines have been chosen as chiral moieties. They were prepared in optically active form from (s)-beta-amino alcohols via a short stereospecific synthesis and incorporated into mesogenic systems. Mesogenic and ferroelectric properties of 11 compounds in five series of chiral oxazoline derivatives [I(OH), I(H), II(OH), II(H), and III(OH)] have been studied. In order to establish the relationship between the molecular structure and ferroelectric properties, an in-depth structural investigation of both H-bonded and non-H-bonded phenyloxazoline moieties was carried out (by means of semiempirical calculations-AM1-and spectroscopic studies-IR, UV and H-1 NMR). These studies have proved a planar structure for both types of structures, which should have a strong influence on ferroelectric properties. These properties have been evaluated in 10 mol % binary mixtures. The highest Ps values were measured for compounds of series I(OH) [P-s max(I(OH)a) = 16.7 nC/cm(2), P-s max(I(OH)b) = 13.2 nC/cm(2)] containing a hydrogen bond, which makes the chiral part of the molecule more rigid. Compound III(OH)a shows a wide SmC* phase range which supercools well below room temperature, and it has been studied as a ferroelectric liquid crystal in the pure state. The P-s max measured is appreciably high: 225 nC/cm(2). Its special thermal behavior (showing a glass transition at -28 degrees C) makes this compound very interesting from the point of view of practical applications and will be the target of further studies.
Synthesis and SAR Study of Simple Aryl Oximes and Nitrofuranyl Derivatives with Potent Activity Against Mycobacterium tuberculosis
作者:Cristiane França da Costa、Marcus Vinicius Nora de Souza、Maria Cristina da Silva Lourenço、Elaine Soares Coimbra、Guilherme da Silva Lourenço Carvalho、James Wardell、Stephane Lima Calixto、Juliana da Trindade Granato
DOI:10.2174/1570180816666181227115738
日期:2019.12.31
Background: Oximes and nitrofuranyl derivatives are particularly important compounds in medicinal chemistry. Thus, many researchers have been reported to possess antibacterial, antiparasitic, insecticidal and fungicidal activities. Methods: In this work, we report the synthesis and the biological activity against Mycobacterium tuberculosis H37RV of a series of fifty aryl oximes, ArCH=N-OH, I, and eight
Abstract The reaction of a variety of aldoximes with perfluoroalkanosulfonyl fluoride in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane smoothly generated the corresponding nitriles in 70%–95% yields.
作者:Jinyi Song、Hongyan Zhao、Yang Liu、Huatao Han、Zhuofei Li、Wenyi Chu、Zhizhong Sun
DOI:10.1039/c6nj02815b
日期:——
synthesized using the Vilsmeier–Haack reaction and oximation. 2,5-Dihydroxyterephthalaldehyde dioxime (L8) as an efficient N,O-symmetrical bidentate ligand was prepared from hydroquinone. It was studied as a high activity ligand for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of arylchlorides with arylboronic acids under mild conditions. The couplingreactions were performed in the presence
使用Vilsmeier-Haack反应和肟化合成了一系列N,O-双齿配体。由对苯二酚制备作为有效的N,O-对称双齿配体的2,5-二羟基对苯甲醛二肟(L 8)。作为温和条件下芳基氯化物与芳基硼酸的钯催化的Suzuki-Miyaura交叉偶联反应的高活性配体,已对其进行了研究。偶联反应在PdCl 2作为催化剂,L 8作为配体,Na 2 CO 3存在下进行在85°C下,PEG-400作为PTC,在乙醇/水(1:1)中作为对环境无害的溶剂。通过优化的反应在0.20 mol%的低钯负载下以良好的收率获得了大量的联芳基。
Heterogeneous Catalytic Method for the Conversion of Aldoximes into Nitriles Using Molecular Sieve Modified with Copper(II)
作者:Árpád Kiss、Zoltán Hell
DOI:10.1080/00397911.2012.667861
日期:2013.7.3
Abstract A simple heterogeneous metal-catalyzed method was developed for the transformation of aldoximes into nitriles. Molecular sieve (4 Å) modified with copper(II) proved to be an efficientcatalyst for the conversion. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT
摘要 开发了一种简单的多相金属催化方法将醛肟转化为腈。经铜 (II) 改性的分子筛 (4 Å) 被证明是转化的有效催化剂。补充材料可用于本文。转至出版商的 Synthetic Communications® 在线版以查看免费的补充文件。图形概要
4-Cyanoresorcinol-Based Bent-Core Mesogens with Azobenzene Wings: Emergence of Sterically Stabilized Polar Order in Liquid Crystalline Phases
compounds, ranging from cybotactic nematic via paraelectric SmC phases, polarization randomized SmCsPR phases to ferroelectric and antiferroelectric SmC phases, associated with increasing size and correlation length of the polar domains. Spontaneous formation of chiral domains is observed in the paraelectric SmC and the SmCsPR phases and discussed in relation with superstructural chirality, bend elastic
合成了一系列新的含偶氮苯的弯曲核分子,这些弯曲核分子以4-氰基间苯二酚为中心核心单元,表现出等向性向列相,矩形,柱状和不同类型的倾斜近晶(SmC)相。使用各种实验技术,可以在块状和自由悬浮的薄膜中表征中间相的行为和相结构。根据链长和温度的不同,在这些化合物中观察到一系列不同的中间相,从顺向向列相到顺电SmC相,到极化随机的SmC s P R。相到铁电和反铁电SmC相,这与极性域的大小和相关长度增加有关。在顺电SmC和SmC s P R相中观察到手性域的自发形成,并讨论了与超结构手性,弯曲弹性常数和表面效应有关的问题。