Two series of phenylbenzylether and benzanilide based rod-like imidazolium bromides and their nonionic precursors, the 1-phenyl-1H-imidazoles have been synthesized and the influence of the number and length of the alkyl chain(s) and the structure of the linking group in the aromatic core (–CH2O–, –COO–, –CONH–) on their mesophase self-assembly in ionic liquid crystalline phases were studied by POM, DSC and XRD. Upon decreasing the length of the N-terminal chain or by enlarging the number and length of the C-terminal chains, the sequence smectic (SmA)–hexagonal columnar (Colhex)–micellar cubic (CubI/Pm3n) was found for the ether based imidazolium salts; while only SmA and Colhex phases were observed for the related amides. The influence of the polarity of the central linkages, namely –CH2O– and –CONH–, on the mesophase structure and stability is discussed and compared with related –COO– connected ILC.
Thus, a lamellar smectic A phase, a bicontinuous cubic Ia3d phase, and a columnar hexagonal liquid crystalline mesophase are induced as a function of increasing chain length. The mesomorphic properties were studied by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction, and with the support of dilatometry and molecular dynamics, models for the various supramolecular
Seven dimeric cationic lipids possessing an aromatic anchor between the hydrocarbon chains and cationic headgroup have been synthesized. The spacers in these lipids vary in length, hydrophobicity and flexibility. The synthesis, membrane-forming properties and complexation with plasmid DNA (lipoplex formation) are briefly described. (c) 2006 Elsevier Ltd. All rights reserved.