180678-33-5Relevant academic research and scientific papers
Self-assembly of imidazolium-based rodlike ionic liquid crystals: transition from lamellar to micellar organization
Cheng, Xiaohong,Bai, Xueqing,Jing, Shan,Ebert, Helgard,Prehm, Marko,Tschierske, Carsten
supporting information; experimental part, p. 4588 - 4601 (2010/08/19)
By using aryl-amination chemistry, a series of rodlike 1-phenyl1H- imidazole-based liquid crystals (LCs) and related imidazolium-based ionic liquid crystals (ILCs) has been prepared. The number and length of the C-terminal chains (at the noncharged end of the rodlike core) and the length of the N-terminal chain (on the imidazolium unit in the ILCs) were modified and the influence of these structural parameters on the mode of self-assembly in LC phases was investigated by polarizing microscopy, differential scanning calorimetry, and X-ray diffraction. For the single-chain imidazole derivatives nematic phases (N) and bilayer SmA2 phases were found, but upon increasing the number of alkyl chains the LC phases were lost. For the related imidazolium salts LC phases were preserved upon increasing the number and length of the C-terminal chains and in this series it leads to the phase sequence SmA-columnar (Col)-micellar cubic (Cuby1/Pm3n). Elongation of the N-terminal chain gives the reversed sequence. Short Nterminal chains prefer an end-to-end packing of the mesogens in which these chains are separated from the C-terminal chains. Elongation of the N-terminal chain leads to a mixing of N- and C-terminal chains, which is accompanied by complete intercalation of the aromatic cores. In the smectic phases this gives rise to a transition from bilayer (SmA2) to monolayer smectic (SmA) phases. For the columnar and cubic phases the segregated end-to-end packing leads to core-shell aggregates. In this case, elongation of the N-terminal chains distorts core-shell formation and removes Cub1 and Col phases in favor of single-layer SmA phases. Hence, by tailoring the length of the N-terminal chain, a crossover from taper-shaped to polycatenar LC tectons was achieved, which provides a powerful tool for control of self-assembly in ILCs.
Lanthanide luminescent mesomorphic complexes with macrocycles derived from diaza-18-crown-6
Suárez, Stéphane,Mamula, Olimpia,Scopelliti, Rosario,Donnio, Bertrand,Guillon, Daniel,Terazzi, Emmanuel,Piguet, Claude,Bünzli, Jean-Claude G.
, p. 1323 - 1334 (2007/10/03)
Four tetracatenar (L1-L4) and one hexacatenar (L5) ligands, derived from the diaza-18-crown-6 framework, are synthesized and characterized. In these ligands, the amine functions are fitted with benzoyloxybenzyl linker groups, attached either with a carbon
Tailoring thermotropic cubic mesophases: Amphiphilic polyhydroxy derivatives
Borisch, Konstanze,Diele, Siegmar,Goering, Petra,Kresse, Horst,Tschierske, Carsten
, p. 529 - 543 (2007/10/03)
Novel amphiphilic polyhydroxy compounds [N-(3,4-dialkoxybenzoyl)-1-amino-1-deoxy-D-glucitols (glucamides), N-(3,4-dialkoxybenzoyl)-1-deoxy-1-methylamino-D-glucitols, N-(3,4,5-trialkoxybenzoyl)-1-deoxy-1-methylamino-D-glucitols (N-methylgucamides), 1-benzo
Phasmidic phases in macrocyclic liquid crystals
Tuffin, Rachel P.,Toyne, Kenneth J.,Goodby, John W.
, p. 1271 - 1282 (2007/10/03)
In this article we describe the synthesis, characterisation and phase behaviour of some phasmidic liquid crystals containing the diaza 18-crown-6 macrocyclic core. Seven compounds were synthesised, five tetracatenar and two hexacatenar. The terminal alkoxy chains were varied in length from ten to eighteen carbon atoms, and the number of phenyl rings in the mesogenic units was set at either two or three. Depending on the nature of the mesogenic moiety, hexagonal columnar phasmidic and smectic phases were found to occur for these systems. The natures and structures of the columnar phases found for these systems are discussed in relation to the conformational structure of the macrocyclic core and to the overall geometry, shape and flexibility of the molecular structures.
Influence of lateral alkoxy substitution on mesomorphic properties of copper complexes
Berdague, Philippe,Perez, Felix,Courtieu, Jacques,Bayle, Jean-Pierre
, p. 335 - 343 (2007/10/02)
Coordination complexes between copper and some lateral alkoxy chain-substituted N-(4-(4'-alkoxybenzoyloxy)salicylidene)-4-n-butylaniline have been synthesized.The lateral chain was introduced on the outer ring bearing the ester function.In the case of a 3,4-disubstitution, the mesomorphic behavior is related to the number of carbons in the terminal chain.If this is too small, the mesomorphic properties of the complexes disappear.In contrast, copper complexes are liquid crystalline and show more ordered phases by comparison with the free ligand.In case of a 2,4-disubstitution, the phases are nematic and the clearing temperatures are near room temperature, but the observed phases are essentially monotropic for the ligands, as well as for the complexes.Keywords: nematic / copper complex / lateral substitution / Schiff base
