共查询到20条相似文献,搜索用时 187 毫秒
1.
氟原子在药物分子设计中的应用 总被引:2,自引:0,他引:2
含氟药物在临床治疗药物中占有相当比重.将氟原子或含氟基团引入到小分子药物中,是药物化学结构改造的重要研究策略之一.综述了氟原子在药物分子设计中的应用,氟原子或含氟基团的引入可以调节药物小分子的物理化学特性,改变小分子的药代动力学性质,提高药物的生物利用度;通过影响化合物的构象,增强配体与靶标蛋白的相互结合能力以及对其它靶标蛋白的选择性;通过阻断易代谢位点进而提高药物代谢稳定性等. 相似文献
2.
3.
4.
Goniothalamin是由番荔枝科(annonaceae)家族中分离出的抗肿瘤活性天然产物分子,具有苯乙烯基及α,β-不饱和-δ-内酯两个关键片段。药物化学家近年来利用氟原子或者含氟基团对这两个关键药效基团进行了系统的结构修饰,试图利用氟独特的物理化学性质调控药效基团电子属性以获取具有更佳生理活性的化合物。本文主要从含氟基团引入的位点设计以及合成方法角度,总结了goniothalamin内酯含氟修饰物合成与生理活性研究进展,并进行了发展前景展望。 相似文献
5.
6.
含氟基团对液晶垂直排列的作用 总被引:1,自引:0,他引:1
实验发现双酚A双肉桂酸酯和六氟双酚A双肉桂酸酯单体在线偏振紫外光作用下发生光交联,形成的薄膜对液晶分子的排列效果截然不同,分别诱导液晶分子沿面平行排列和垂直排列.红外光谱分析表明光交联的类型均为[2+2]环加成反应.利用原子力显微镜观察薄膜表面,没有发现明显的各向异性拓扑分布.通过测量非含氟和含氟两种交联膜的表面能大小,发现氟的引入使薄膜的表面能降低,同时表面能中的极性作用明显降低.实验结果表明,氟基团的引入导致液晶分子垂直排列.本文探讨了这种垂直排列的原因. 相似文献
7.
8.
9.
<正>随着自由基化学以及光氧化还原催化的发展,对消旋烷基亲电底物的催化不对称亲核取代反应已经取得了显著进展[1-2],但是,针对含氟亲核试剂所参与的催化不对称亲核取代反应的研究仍然非常有限,主要是因为氟原子具有最大的电负性和除氢原子以外最小的原子半径, 相似文献
10.
对具有N-(对甲基丙烯酰氧基苄叉基)取代苯胺骨架的一系列侧链型Schiff碱液晶单体合成进行了研究,苯胺环上的取代基为卤素、强吸电子基及大体积基团,考察了取代基对液晶性质的影响。当取代基为4-氯,4-溴时,单体呈狭窄之液晶区间,而2,4-二氯取代物则无液晶性。当苯胺环上带有4-苯基的单体时,都呈宽的液晶区间。同时还对相应单体的自由基聚合及聚合物的相行为进行了研究。 相似文献
11.
The monolayer behavior of long-chain esters of acrylic and methacrylic acids containing perfluoro or partially fluorinated carbon chains at the air/water interface was studied by surface pressure-area isotherm measurements and Brewster angle microscopy. It has been found that a minor change in the chemical structures of these fluorinated amphiphiles, such as a hydrogen substituted at the omega-position of the hydrophobic fluorocarbon tails instead of a fluorine as well as hydrophilic vinyl ester groups inserted between acrylates and methacrylates, induces a drastic change in the isotherms for the monolayers, suggesting different molecular orientation and packing in the films. The monolayers were transferred by horizontal lifting, Langmuir-Blodgett, and surface-lowering methods to give the X-, Y-, and Z-type films, respectively. These films were characterized by scanning probe microscopy, to clarify the mesoscopic surface structures of the molecular films exposed with the hydrophilic or hydrophobic moieties in air, depending upon the dipping methods. The Z-type films with the outermost surface of the fluorinated substituents were examined in relation to the frictional properties that strongly depend upon the fluorine and the hydrogen atoms at the end of the hydrophobic fluorocarbon chains, which is controllable at the atomic level. 相似文献
12.
In this paper we highlighted the synthesis, characterization, and practical exploitation of different types of polyphosphazenes substituted with fluorinated groups. There are several ways in which fluorine atoms can be inserted into polyphosphazenes, all of which leading to different polymers showing a wide range of characteristics. In general it is true that the insertion of fluorine atoms into phosphazene macromolecules leads to an enhancement of the thermal stability, flame resistance, low-temperature elastomericity, and chemical inertness of the phosphazenes obtained. The contribution of Italian research groups to the preparation and exploitation of organic commercial macromolecules grafted onto fluorinated polyphosphazenes is also reviewed. 相似文献
13.
Nicoletti M Bremer M Kirsch P O'Hagan D 《Chemical communications (Cambridge, England)》2007,(47):5075-5077
The synthesis of the stereospecifically fluorinated difluoro- and trifluoro- rac-3 and rac-4 is described where the fluorine atoms are positioned adjacent/vicinal to each other and the physical characteristics of these candidate liquid crystals including negative dielectric anisotropy are measured and rationalised. 相似文献
14.
Yufang Liu Heng Ma Houju Xu Jinfeng Sun Keli Han 《International journal of quantum chemistry》2005,102(4):415-421
We have investigated the relationship between the molecular configuration and dipole moment of some fluorinated liquid crystals (LCs). The geometries of the molecules were preliminarily optimized at empirical AM1 and then were further optimized at B3LYP/6‐31G(d) level. The dipole moment has been calculated. It is strongly influenced by the position and number of fluorine substituents in the benzene ring of the molecule. The polarizability, mean polarizabilities, and anisotropic polarizability of the phenylbicyclohexane (PBC) fluorine substituents are also given and discussed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
15.
本文综述了液晶二聚体、多爪型液晶及香蕉形液晶等几类非常规液晶材料的研究进展。结合笔者近几年的研究积累,着重介绍:(1)液晶二聚体的分子结构与液晶态结构及液晶二聚体所特有的奇偶效应与近晶多形性;(2)多爪型液晶的分子结构与液晶态结构的特点及由于兼有棒状分子与盘状分子的结构特点而具备的特殊的相变性质;(3)香蕉形液晶的分子结构与液晶态结构及香蕉形液晶所特有的手性与极化序。在介绍各类液晶材料的特点及研究热点的同时,围绕分子结构与液晶态结构的关系这一主题,深入讨论了各种液晶材料形成特殊分子排列及表现出特殊物理性质的机理。 相似文献
16.
Yuwen Zeng Chuanfa Ni Prof. Dr. Jinbo Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3210-3223
Fluorinated ketones are intriguing compounds in synthetic chemistry and life science‐related fields. The development of efficient methodologies to obtain these compounds is of significant importance and has therefore attracted considerable attention. This Minireview highlights recent progress made in the synthesis of fluorine‐containing ketones, with an emphasis on those methods in which the construction of carbonyl groups is synergetic with distal (β‐, γ‐, δ‐, etc.) incorporation of fluorine atoms or fluorinated groups. 相似文献
17.
Fluorinated tolanes, produced by introducing fluorine atoms into one of the aromatic rings of tolane, emitted almost no fluorescence in a solution state, but the fluorescence intensity increased dramatically in the crystalline state because of intermolecular H⋅⋅⋅F hydrogen bonds. The photoluminescent (PL) colors depend on the molecular orbitals, dipole moments, and molecular aggregated structures can be varied by controlling terminal substituents along the major molecular axis. The introduction of a long alkoxy or semifluoroalkoxy unit as a flexible chain into the terminal positions along the major molecular axis induced the formation of a liquid-crystalline (LC) phase; fluorinated tolanes act both as luminophores and as mesogens, leading to the molecular design of new photoluminescent LC molecules (PLLCs). The results also indicated that a fluorinated tolane dimer, which consists of two fluorinated tolanes linked by a flexible alkylene spacer, also becomes a novel PLLC. 相似文献
18.
The single charge transfer through acenes, partially H-F substituted acenes, and fluoroacenes is discussed. The reorganization energies between the neutral molecules and the corresponding monoanions for partially H-F substituted acenes lie between those for acenes and fluoroacenes. The delocalization of the lowest unoccupied molecular orbitals (LUMO) by substituting hydrogen atoms by fluorine atoms with the highest electronegativity in every element is the main reason why the reorganization energy between the neutral molecule and the monoanion for partially H-F substituted acenes lies between those for acenes and fluoroacenes. This result implies that the negatively charged partially H-F substituted acenes would be better conductors with rapid electron transfer than the negatively charged fluoroacenes if we assume that the overlap of the LUMO between partially H-F substituted acenes is not significantly different from that between two neighboring fluoroacenes. The structures of the monoanions of acenes, fluoroacenes, and partially H-F substituted acenes are optimized under D2h geometry, and the Jahn-Teller effects in the monoanions of benzene and fluorobenzene are discussed. The vibration effect onto the charge transfer problem is also discussed. The C-C stretching modes around 1500 cm(-1) are the main modes converting the neutral molecules to the monoanions in acenes, fluoroacenes, and partially H-F substituted acenes. It can be confirmed from the calculational results that the C-C stretching modes around 1500 cm(-1) the most strongly couple to the LUMO in these molecules. The main reason why the total electron-phonon coupling constants (lLUMO) for the monoanions of acenes in which four outer hydrogen atoms are substituted by fluorine atoms are larger than those for the monoanions of acenes in which several inner hydrogen atoms are substituted by fluorine atoms is suggested. The relationships between the electron transfer and the electron-phonon interactions are discussed. The plot of the reorganization energies against the lLUMO values is found to be nearly linear. In view of these results, the relationships between the normal and superconducting states are briefly discussed. 相似文献
19.
In this study, we synthesized a series of fluorinated and non-fluorinated tolanes, in which one or more fluorine atoms were systematically introduced into one aromatic ring of a tolane scaffold, and systematically evaluated their photophysical properties. All the tolanes with or without fluorine substituents were found to have poor photoluminescence (PL) in tetrahydrofuran (THF) solutions. On the other hand, in the crystalline state, non-fluorinated and fluorinated tolanes with one or four fluorine atoms were less emissive, whereas fluorinated tolanes with three or five fluorine atoms exhibited high PL efficiencies (ФPL) up to 0.51. X-ray crystallographic analyses of the emissive fluorinated tolanes revealed that the position of the fluorine substituent played a key role in achieving a high ФPL. Fluorine substituents at the ortho (2/6) and para (4) positions led to tight and rigid packing due to plural π–π stacking and/or hydrogen bonding interactions, resulting in enhanced ФPL caused by the suppression of non-radiative deactivation. Additionally, fluorinated tolanes with three fluorine atoms exhibited notable aggregation-induced PL emission enhancement in THF/water mixed solvents. This demonstrates that the PL characteristics of small PL materials can be tuned depending on the usage requirements. 相似文献
20.
Fujimori A Nakahara H Ito E Hara M Kanai K Ouchi Y Seki K 《Journal of colloid and interface science》2004,278(1):184-191
With comb polymers with different kinds of fluorocarbon side-chains, significant effects of spreading solvents on the monolayers at the air/water interface and the molecular arrangement in the deposited films could be found by the use of trifluoroacetic acid and its mixed solvents with n-hexane, depending on the atoms, fluorine or hydrogen, substituted at the end of the fluorocarbon side-chains. These facts are probably due to intralayer hydrogen bonding cooperating with the carbonyl groups of the long-chain esters. The deposited films of solid substrates were characterized by polarized near-edge X-ray absorption fine structure (NEXAFS) spectroscopy as well as in-plane X-ray diffraction and scanning electron and atomic force microscopy. 相似文献