168832-34-6Relevant articles and documents
Synthesis, mesomorphic properties and nonlinear optical studies of alkyl and alkoxy phenylacetylene containing phenazine fused extended triphenylene discotic liquid crystalline dyes
Gowda, Ashwathanarayana,Jacob, Litwin,Patra, Alakananda,George, Agnes,Philip, Reji,Kumar, Sandeep
, p. 128 - 135 (2018/08/07)
Herein, we have reported the alkyl and alkoxy phenylacetylene containing phenazine fused triphenylene discotic liquid crystals (DLCs) which are obtained by the condensation reaction of triphenylene-1,2-diquinone with 1,2-diamino-4,5-dibromobenzene, followed by Sonogashira C–C coupling reaction with 4-alkyl-phenylacetylene or 4-alkoxy-phenylacetylene. Six novel derivatives were synthesized and evaluated for their thermal and optical properties. They show a broad range of hexagonal columnar phase and retain their mesophase up to room temperature upon cooling from the isotropic liquid. Thermotropic liquid crystalline properties of all the compounds were studied by polarised optical microscopy (POM), differential scanning calorimetry (DSC). The self-assembly of mesophase structure was investigated by X-ray diffraction (XRD) studies. Thermogravimetric analysis of all the mesogens shows good thermal stability over a broad temperature range. The photophysical properties of newly synthesized compounds were measured using UV–Vis absorption and photoluminescence emission spectroscopy in anhydrous chloroform solvent. The π-extended conjugation in these mesogens exhibit strong absorption bands falling around 270–487 nm and corresponding emission band at 657–663 nm respectively. The high delocalization of π– electrons in extended discotic mesogens show high nonlinear optical properties when measured under excitation by nanosecond laser pulses at 532 nm. These materials may find distinctive applications in the semiconducting devices.
Synthesis and mesomorphic properties of some fluorinated benzoate liquid crystals
Yang, Yong Gang,Chen,Tang,Wen
, p. 1 - 15 (2007/10/03)
Three series of [4-(4′-n-alkyloxyphenyl)acetylenyl]-2,6- difluorophenyl fluorinated benezoates and one series of fluorinated benzoates with 2,3,5,6-tetrafluorophenylene group and semi-perfluorocarbon chain have been synthesized. Their phase transition temperatures have been measured by texture observation in a polarizing microscope and confirmed by DSC. For the series without fluorocarbon chains, increasing the quantity of fluorosubstituents on the terminal phenyl groups decreased nematic stability (TN-I), but the breadth of the SmA phase range was increased. Lateral fluorosubstitution in the central group lowered the nematic stability (TN-I) and decreased the breadth of the SmA phase range. The series with semiperfluorocarbon chains were more likely to form SmA phases than the series with hydrogencarbon chains, and with the increasing of fluorosubstituents quantity on the terminal phenyl groups nematic and SmA stability (TN-I and TsmA-N) were both decreased.
