The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• phase (Table 1, Figure 2). The transition to the SmC phase was not found in DSC analysis (Figure 3), due to its low transition enthalpy value. The transition from SmA to SmC, passing through broken fan-shaped focal conic texture for compound 19 is shown in Figure 2. Amide 20 displayed polymorphism Cr

• , isoxazoline derivatives induce the formation of an SmA mesophase by lateral diffusion, while isoxazole derivatives favor the formation of a nematic mesophase by longitudinal diffusion, along SmA mesophase [27]. In addition, for amide 19, a second smectic mesophase was identified by POM as the monotropic SmC

Novel biphenyl-substituted 1,2,4-oxadiazole ferroelectric liquid crystals: synthesis and characterization

• Mahabaleshwara Subrao,
• Dakshina Murthy Potukuchi,
• Girish Sharada Ramachandra,
• Poornima Bhagavath,
• Sangeetha G. Bhat and
• Srinivasulu Maddasani

Beilstein J. Org. Chem. 2015, 11, 233–241, doi:10.3762/bjoc.11.26

• ; SmC* phase; spontaneous polarization; Suzuki coupling; Introduction The 1,2,4-oxadiazole derivatives are prevalently reported compounds with promising biological [1][2][3][4][5] and physiological [6][7][8] activity such as antiinflammatory, antibacterial, antimicrobial, antifungal, anticancer

• . [25] demonstrated the FE nature in tilted smectic-C (SmC) phase of LC materials for the first time and then proved that the FELCs are potential candidates for EO display devices owing to their large birefringence, fast response [26] and large viewing angles. The ferroelectric materials possess [27][28

• simultaneous observation of threads and broken focal conic fan texture infers [39] that the LC phase is a tilted smectic phase. This texture is found to be similar to the texture reported [40] for the polar smectic-C (SmC*) phase of octyl 4-(4-(3-(4'-(undec-10-en-1-ylcarbonyloxy)biphenyl-4-carbonyloxy

Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties

• Alexej Bubnov,
• Miroslav Kašpar,
• Věra Hamplová,
• Ute Dawin and
• Frank Giesselmann

Beilstein J. Org. Chem. 2013, 9, 425–436, doi:10.3762/bjoc.9.45

• transition (157 °C) is found to be pronouncedly higher than that observed for TL1. Below the SmC phase a crystal modification (denoted as Cr1 phase) has been detected for TL4 and TL1. For TL3 no liquid-crystalline behaviour has been detected: only a modification of a crystalline phase (denoted as Cr1) exists

• obtained at 108 °C on free-standing films (FSF) (Figure 1b), and the N–SmC phase transition obtained at about 102 °C on FSF (Figure 1c). DSC plot on heating/cooling runs for indicated nonchiral TL1, TL3 and TL4 and for chiral TL2 and TL5 are presented in Figure 2 and Figure 3, respectively. The blue phase

• been clearly detected in the SmC* phase but due to the monotropic (supercooled) character of the phase it was not possible to measure and study the spontaneous quantities in detail, namely the spontaneous polarization and tilt angle. For this compound the microphotographs of textures obtained in POM

Formation of smectic phases in binary liquid crystal mixtures with a huge length ratio

• Nadia Kapernaum,
• Friederike Knecht,
• C. Scott Hartley,
• Jeffrey C. Roberts,
• Robert P. Lemieux and
• Frank Giesselmann

Beilstein J. Org. Chem. 2012, 8, 1118–1125, doi:10.3762/bjoc.8.124

• the SmC phase, which was the dominant phase in most of the pure compounds, was reduced while the SmA phase became broader. In the systems with a length ratio of 1.8, the smectic A phase was the only stable mesophase over a broad temperature and concentration range. Furthermore, a decrease of the tilt

• angle θ of the SmC phase, as well as a reduced smectic order parameter Σ in the SmA phase, were observed for these systems. We showed that the ordering of the bidisperse molecules in a SmA phase can be explained by extensive out-of-layer fluctuations (Figure 1) [1][2]. In a SmA phase of strongly

• experimental data and reflects the molecular ordering in the smectic phases of bidisperse molecules best. The preference for the SmA over the SmC phase, which was observed for all systems with a large length ratio, may also be explained by extensive out-of-layer fluctuations [2]. The molecules in a nontilted

Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

• Govindaswamy Shanker,
• Marko Prehm and
• Carsten Tschierske

Beilstein J. Org. Chem. 2012, 8, 472–485, doi:10.3762/bjoc.8.54

• spacer, displays a SmC–NcybC dimorphism and, remarkably, the SmC phase is removed for the longer homologue Thia-Ox/10. A N-to-SmC transition is observed at T = 172–173 °C for the dimesogen Thia-Ox/5 on reduction of the temperature (Figure 5) [68]. In contrast to the NcybA–CybA-transition, for which no

• structure of the SmC phase in which the aromatic cores and the relatively short spacer units form one type of layer, which is separated by the layers formed by the aliphatic end-chains (Figure 4a). In the layers of the core units, the 3,5-diphenyl-1,2,4-oxadiazole-, 2-phenyl-1,3,4-thiadiazole and the

• -Ox/5, has exclusively a nematic phase and no transition to a SmC phase could be observed optically on cooling the sample down to 123 °C, at which point crystallization starts. The XRD pattern of a magnetically aligned sample (B = 1 T) of this nematic phase shows a crescent-like diffuse wide-angle

Perhydroazulene-based liquid-crystalline materials with smectic phases

• Zakir Hussain,
• Henning Hopf and
• S. Holger Eichhorn

Beilstein J. Org. Chem. 2012, 8, 403–410, doi:10.3762/bjoc.8.44

• several liquid-crystalline phases over a wide temperature range. Variable-temperature optical polarized microscopy (vt-OPM) and differential scanning calorimetry (DSC) measurements revealed that compound 8b is converted into a SmC phase at ~28 °C and converts into a short-temperature-range SmA and N phase

• at ~101 °C and 107 °C, respectively. The conversion of the nematic phase to the isotropic phase in the case of 8b was observed at 117 °C. Similar investigations on phase transitions of compound 10b revealed that this material melts into a SmC phase at a much higher temperature, i.e., ~94 °C, compared

Molecular length distribution and the formation of smectic phases

• Nadia Kapernaum,
• C. Scott Hartley,
• Jeffrey C. Roberts,
• Robert P. Lemieux and
• Frank Giesselmann

Beilstein J. Org. Chem. 2009, 5, No. 65, doi:10.3762/bjoc.5.65

• order – to be the ideal liquid crystalline (LC) phase for accommodating molecules of substantially different lengths. On the other hand the smectic phases – due to their layer structure – seem to be unsuited to accommodate molecules of different lengths. Comparing SmC and SmA, the SmC phase might be

• of the layer spacing with significant layer shrinkage due to the molecular tilt in SmC of about 7% at T−Tc = 20 K. In the mixture with 5% PhP14 the layer shrinkage in the SmC phase is reduced to only 5%. Very small layer shrinkage of only 1% was found for the mixture with 70% PhP14. And for the

• mixture with 65% PhP14 no layer shrinkage at all could be found, although by polarizing microscopy the broken fan-shaped texture of a SmC phase was clearly observed (see Figure 6). To gain a deeper understanding of these smectic phases the optical tilt angle of the mixtures was measured in the