从液晶和光学的观点出发,合成并研究了两个被一个或两个氰基基团侧向取代的带有对-叔苯基的甲基丙烯酸酯单体。合成路线涉及多个反应,包括允许芳基偶联的铃木反应。1 H和13证实了这些新单体及其相应前体的化学结构。13 C NMR光谱学。通过差示扫描量热法(DSC),偏振光学显微镜(POM)和X射线衍射(XRD)分析研究了单体和前体的介晶行为。与带有两个氰基的分子相比,带有一个氰基的分子在较低的温度下熔化并在较大的温度区间内表现出介晶行为。四种化合物(两种单体和两种前体)仅显示无序近晶相。通过X射线衍射,确定了分子在近晶相内以单层堆叠,除了单体以双层堆叠。电化学表征表明这些分子表现为p型材料,并且可以通过引入CN基团来调节其电子性质(带隙)。分子在蓝色光谱范围(高能光区域)中吸收和发射。较大的斯托克斯位移表明,分子的几何形状从电子基态的芳香族转变为第一激发态的更共面的醌型结构。荧光量子产率很高(7
Supramolecular dendrimers: Unusual mesophases of ionic liquid crystals derived from protonation of DAB dendrimers with facial amphiphilic carboxylic acids
作者:Andrew G. Cook、Ute Baumeister、Carsten Tschierske
DOI:10.1039/b415892j
日期:——
Supramolecular liquid crystalline (LC) dendrimers were prepared by self-assembly of first to fifth generation amino terminated DAB dendrimers with facial amphiphilic carboxylic acids. These carboxylic acids are composed of three distinct incompatible segments, a rigid rod-like terphenyl core, two terminal alkyl chains and a polar lateral carboxylate group. The COOH groups were either directly connected to the terphenyl core or via oligo(oxyethylene) chains of different lengths. Depending upon the length of the polyether chain used, the dendrimer generation, the ratio of dendrimer to carboxylic acid or the temperature, a series of six different LC phases were observed. As well as a smectic phase (SmA), two different square columnar phases (Colsqu), a mesophase combining a layer structure with a hexagonal organisation of columns (channelled layer phase, ChLhex) and two additional mesophases (Colhex and M) with unknown structures were found. The square columnar phases are either composed of square cylinders (plane group p4mm) or a regular arrangement of square and triangular cylinders (plane group p4gm). In these dendrimer–carboxylic acid complexes protons are transferred from the COOH groups to the amino groups of the dendrimer, which gives rise to ionic complexes (dendroelectrolyte–amphiphile complexes). This concept allows the tailoring of the mesomorphic properties in a thermodynamically controlled self assembly process. The T-shaped ternary amphiphilic structure of the acid components and the incompatibility of the ionic species formed during the self assembly process are responsible for the formation of unconventional mesophase structures.
Synthesis and mesomorphic properties of 1,1-difluoroalkyl-substituted biphenylthienyl and terphenyl liquid crystals. A comparative study of mesomorphic behavior relative to alkyl, alkoxy and alkanoyl analogsElectronic supplementary information (ESI) available: experimental details for compounds 4, 9, 10, 12, 15–19, 25–39, 45 and 49. See http://www.rsc.org/suppdata/jm/b1/b102059p/
作者:Andre A. Kiryanov、Paul Sampson、Alexander J. Seed
DOI:10.1039/b102059p
日期:2001.11.23
A variety of biphenylthienyl and terphenyl-based liquid crystalline materials were prepared that incorporate a 1,1-difluoropentyl terminal group. The mesogenic properties of these compounds were compared and contrasted with analogs where the CF2 moiety was replaced by a -CH2-, -O- or -CO- group. The 1,1-difluoroalkyl group is unique in its behavior and tends to promote orthogonal smectic phase behavior.
作者:Moisés Alberto Valdés-Pech、Leticia Larios-López、Rosa Julia Rodríguez-González、Isaura Felix-Serrano、Nayely Trejo-Carbajal、Dámaso Navarro-Rodríguez
DOI:10.1016/j.jfluchem.2018.11.011
日期:2019.2
p-Terphenyls carrying two or four fluorine atoms in the central ring were synthesized via Suzuki-Miyaura cross-coupling reaction using phenylboronic acids and fluorinated dibromobenzenes. By calorimetric and X-ray diffraction analyses it was found that the p-terphenyls carrying two fluorine atoms develop nematic and/or smectic (A and C) phases. On the contrary, the p-terphenyls substituted with four
p -Terphenyls携带在所述中心环的两个或四个氟原子分别通过Suzuki-Miyaura交叉偶联反应使用的苯基硼酸和氟化dibromobenzenes合成。通过量热和X射线衍射分析发现,带有两个氟原子的对-三联苯形成向列相和/或近晶相(A和C)。相反,被四个氟原子取代的对叔苯基不是液晶。π -差异的热行为在术语π解释发现˚F从吸电子的氟原子的能力所产生的相互作用。这样的π - π ˚F互动让p-三联苯以交错构型堆叠,这解释了近晶C相的稳定性。另一方面,半氟化的对三联苯在电磁波谱的蓝色区域吸收和发射。测得的较大斯托克斯位移表明这些化合物对其自身发出的光几乎透明。这种光学特性与低阶液晶特性相结合,使这些新的对-三联苯成为电致发光器件中线性极化的蓝色发光层的潜在候选者。
Chiral cyclohexyl compounds
申请人:Secretary of State for Defence in Her Britannic Majesty's Government of
公开号:US05853613A1
公开(公告)日:1998-12-29
The present invention describes liquid crystal compounds which are suitable for use in liquid crystal devices including those which exploit the electroclinic effect.
本发明描述了适用于液晶器件中的液晶化合物,包括那些利用电致旋光效应的器件。
Planar and distorted indigo as the core motif in novel chromophoric liquid crystals
作者:Jan H. Porada、Jörg-M. Neudörfl、Dirk Blunk
DOI:10.1039/c5nj01594d
日期:——
The phase behaviour of calamitic indigoid liquid crystals was investigated and rationalised on the basis of a crystal structure analysis.