64581-07-3Relevant academic research and scientific papers
The effects of molecular structure and functional group of a rodlike Schiff base mesogen on blue phase stabilization in a chiral system
Huang, Chiung-Cheng,Huang, Yu-Chang,Hsieh, Wei-Cheng,Chen, Yen-Jung,Jiang, Shi-Kai,Chen, Bo-Hao,Hsu, I.-Jui,Lee, Jey-Jau
supporting information, p. 1743 - 1756 (2019/01/28)
Two types of racemic rodlike Schiff base mesogens with-C═N-(type I) and-N═C-(type III) linkages were prepared. These mesogens possessed either difluoro substitutions at the inner-core position of the phenyl ring or hydroxy group to form intramolecular hyd
Synthesis and mesomorphic properties of novel Schiff base liquid crystalline EDOT derivatives
Gowda, Ashwathanarayana,Roy, Arun,Kumar, Sandeep
, p. 840 - 847 (2016/12/30)
Herein, we reported novel banana liquid crystals derived from ethylenedioxythiophene (EDOT) central unit encompass with Schiff base. Structural charecterization of these compounds was carried out from their spectral and elemental analysis. Physical properties of all the newly synthesized compounds were investigated by polarising optical microscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Raman spectroscopy. EDOT bearing three-ring Schiff base bent-core compounds are non-mesomorphic but all the Schiff bases containing five-rings exhibit enantiotropic mesophase behaviour. The higher homologues show long range nematic phase along with a smectic C phase at lower temperature. While the lower homologues exhibit only N phase. The bent-angle in these compounds is in between of calamitic LCs and banana LCs; therefore, the molecules escape from the polar order packing observed in typical bent core LCs. Detailed XRD investigation endorses the presence of the N phase in lower homologues and Sm C phase in higher homologues.
Synthesis, structural and mesophase characterization of three ring based thiophene liquid crystals
Reddy, M. Kesava,Reddy, K. Subramanyam,Kumar, B.V.N. Phani,Narasimhaswamy
, p. 1 - 24 (2014/07/07)
Thiophene based calamitic mesogens are receiving paramount importance due to their applications in functional organic materials. The insertion of thiophene in the core unit favours a large change in mesophase characteristics as well as application properties in contrast to those mesogens with phenyl ring core alone. In this work, we report the structural as well as mesophase characterization of six mesogens which are built with a core of three phenyl rings and thiophene ring. The thiophene ring is placed at one end of the core and varied the other end with alkyl/alkoxy chains to investigate the mesophase characteristics. The molecular structures of representative mesogens are confirmed by means of FT-IR and Two-dimensional solution NMR techniques. An enantiotropic nematic phase is observed in all the cases as supported by HOPM and DSC techniques. The mesophase characteristics such as melting and clearing temperatures and phase stability are discussed. A dramatic increase in nematic phase stability for the synthesised mesogens is noticed in contrast to two phenyl ring based thiophene mesogens reported in literature.
13C-1H dipolar couplings for probing rod-like hydrogen bonded mesogens
Reddy, M. Kesava,Reddy, K. Subramanyam,Narasimhaswamy,Das, Bibhuti B.,Lobo, Nitin P.,Ramanathan
, p. 3195 - 3206 (2013/10/01)
Hydrogen bonding is the most important non-covalent interaction utilised in building supramolecular assemblies and is preferred often as a means of construction of molecular, oligomeric as well as polymeric materials that show liquid crystalline properties. In this work, a pyridine based nematogenic acceptor has been synthesized and mixed with non-mesogenic 4-methoxy benzoic acid to get a hydrogen bonded mesogen. The existence of hydrogen bonding between the pyridyl unit and the carboxylic acid was established using FT-IR spectroscopy from the observation of characteristic stretching vibrations of unionized type at 2425 and 1927 cm-1. The mesogenic acceptor and the complex have been investigated using 13C NMR in solution, solid and liquid crystalline states. Together with the 2D separated local field NMR experiments, the studies confirm the molecular structure in the mesophase and yield the local orientational order parameters. It is observed that the insertion of 4-methoxy benzoic acid not only enhances the mesophase stability but also induces a smectic phase due to an increase in the core length of the hydrogen bonded mesogen.
Study of mixed mesomorphism in binary systems of azo-ester mesogens with structurally dissimilar nonmesogenic as well as mesogenic ester homologues
Bhatt, Himanshu S.,Patel, Purvang D.,Dave, Jayrang S.
, p. 80 - 91 (2014/01/06)
We have studied mixed mesomorphism in four binary systems comprising two azo-ester mesogens, viz. 4-(4′-n-alkoxybenzoyloxy)3-methylphenyl azo-2″ and 4″-dimethylbenzenes (where n-alkoxy is n-butoxy or n-hexyloxy), and two ester nonmesogenic and mesogenic components, viz. 4-nitrophenyl-4′-n-alkoxybenzoates (where n-alkoxy is n-butoxy or n-hexyloxy). All the four binary systems are mesogenic in nature, showing nematic phase with threaded/marble texture. The phase diagrams of the binary systems are plotted and eutectic transition temperatures and maximum mesophase ranges of the nematic mesophase in all the systems are determined.
Phase characterization and study of molecular order of a three-ring mesogen by 13C NMR in smectic C and nematic phases
Kalaivani,Narasimhaswamy,Das, Bibhuti B.,Lobo, Nitin P.,Ramanathan
, p. 11554 - 11565 (2011/12/15)
Molecules exhibiting a thermotropic liquid-crystalline property have acquired significant importance due to their sensitivity to external stimuli such as temperature, mechanical forces, and electric and magnetic fields. As a result, several novel mesogens have been synthesized by the introduction of various functional groups in the vicinity of the aromatic core as well as in the side chains and their properties have been studied. In the present study, we report three-ring mesogens with hydroxyl groups at one terminal. These mesogens were synthesized by a multistep route, and structural characterization was accomplished by spectral techniques. The mesophase properties were studied by hot-stage optical polarizing microscopy, differential scanning calorimetry, and small-angle X-ray scattering. An enantiotropic nematic phase was noticed for lower homologues, while an additional smectic C phase was found for higher homologues. Solid-state high-resolution natural abundance 13C NMR studies of a typical mesogen in the solid phase and in the mesophases have been carried out. The 13C NMR spectrum of the mesogen in the smectic C and nematic phases indicated spontaneous alignment of the molecule in the magnetic field. By utilizing the two-dimensional separated local field (SLF) NMR experiment known as SAMPI4, 13C-1H dipolar couplings have been obtained, which were utilized to determine the orientational order parameters of the mesogen. ? 2011 American Chemical Society.
Effect of hydrogen-bonded supramolecular assembling on liquid crystal properties of imidazole-containing azomethines and their chelates with copper(II)
Kadkin, Oleg N.,Tae, Jigeon,Kim, Eun Ho,Kim, So Yeon,Choi, Moon-Gun
experimental part, p. 1 - 12 (2010/11/02)
A series of imidazole-containing rod-like Schiff's bases and their ionic copper(II) chelates with various lengths of the terminal alkyl chain containing 6, 8, 10, 12, 14 and 16 carbon atoms have been synthesised. The synthesised compounds were characterised by elemental analyses, 1H NMR, IR and UV-vis and mass spectroscopies. Thermotropic smectic C mesophases in the ligands and smectic A mesophases in the copper(II) complexes were identified using POM, DSC and small-angle XRD scattering methods. X-ray diffraction patterns of the prepared imidazole imines indicate to supramolecular self-assembled structures in the liquid crystal state, which are formed by means of intermolecular hydrogen bonds. It was established that both liquid crystal arrangement and supramolecular assemblies in ligands disappeared near 190°C, mainly regardless of the lengths of the terminal alkyl chains. Contrary, assembling of the copper(II) complexes into supramolecular bilayers occurs near 200°C, which causes their transition to a smectic A mesophase.
