28593-13-7Relevant academic research and scientific papers
New low polar tolane cholesterics designed for infrared applications
Herman, Jakub,Kula, Przemys?aw
, p. 84231 - 84235 (2016/10/06)
We have designed, synthesized and evaluated the physical properties of new fluorinated phenyltolane based chiral liquid crystal materials with 2-methylbutyl terminal chain. The 2- or 2,6-fluorosubstitution in combination with the phenyltolane core brings surprising improvement of mesomorphic properties. The investigated compounds are characterized by a broad temperature range of the cholesteric (chiral nematic N?) phase, very low melting temperatures and easy thermal control of selective reflection in the near infrared region. The moderate helical twisting power β, high optical anisotropy and source of a blue phase make these compounds attractive for cholesteric mixture formulations.
Terminal-Selective Functionalization of Alkyl Chains by Regioconvergent Cross-Coupling
Dupuy, Stéphanie,Zhang, Ke-Feng,Goutierre, Anne-Sophie,Baudoin, Olivier
, p. 14793 - 14797 (2016/11/23)
Hydrocarbons are still the most important precursors of functionalized organic molecules, which has stirred interest in the discovery of new C?H bond functionalization methods. We describe herein a new step-economical approach that enables C?C bonds to be constructed at the terminal position of linear alkanes. First, we show that secondary alkyl bromides can undergo in situ conversion into alkyl zinc bromides and regioconvergent Negishi coupling with aryl or alkenyl triflates. The use of a suitable phosphine ligand favoring Pd migration enabled the selective formation of the linear cross-coupling product. Subsequently, mixtures of secondary alkyl bromides were prepared from linear alkanes by standard bromination, and regioconvergent cross-coupling then provided access to the corresponding linear arylation product in only two steps.
Synthesis and mesomorphic properties of laterally fluorinated alkyl 4′′-alkylterphenyl-4-yl carbonate liquid crystals
Choluj, Artur,Kula, Przemyslaw,Dabrowski, Roman,Tykarska, Marzena,Jaroszewicz, Leszek
, p. 891 - 900 (2014/01/23)
Fifteen series of homologues of a variety of mono-, di- and trifluorosubstituted alkyl 4′′-alkylterphenyl-4-yl carbonates have been synthesized and their mesomorphic properties have been determined. From among 95 prepared compounds, 40 pure nematogens have been found, as well as 55 mesogens with orthogonal and tilted smectic phases in broad temperature ranges. The type and combination of the LC phase strongly depend on the position and number of the fluorine atoms. Physical properties and correlations between the molecular core fluorosubstitution, the length of the terminal chains and the type and sequence of the liquid crystalline phases, have been determined. The compounds are useful for the formulation of nematic mixtures as well as ferroelectric ones.
The synthesis of chiral fluorinated 4-alkyl-4′-[(4-alkylphenyl) ethynyl]biphenyls
Herman, Jakub,Kula, Przemys?aw
, p. 3621 - 3623 (2013/07/05)
We have designed, synthesized, and evaluated the physical properties of new fluorinated phenyltolane based chiral liquid crystal materials with 2-methylbutyl chains. This type of fluoro-substitution in chemical combination with a phenyltolane core brings a surprising improvement to the mesomorphic properties. The investigated compounds exhibit broad temperature ranges for the N* phase and very low melting points. All homologues exhibited Blue Phase. We have applied a Cu-catalyzed cross-coupling reaction between aryl Grignard reagents and alkyl bromides for the synthesis of the products.
