Carbohydrate Rod Conjugates: Ternary Rod−Coil Molecules
Forming Complex Liquid Crystal Structures
Bin Chen
Ute Baumeister
Gerhard Pelzl
Malay Kumar Das
Xiangbing Zeng
Goran Ungar
Carsten Tschierske
10.1021/ja0535357.s001
https://acs.figshare.com/articles/journal_contribution/Carbohydrate_Rod_Conjugates_Ternary_Rod_Coil_Molecules_Forming_Complex_Liquid_Crystal_Structures/3254074
T-shaped polyphilic triblock molecules, consisting of a rodlike <i>p</i>-terphenyl unit, a hydrophilic
and flexible laterally attached oligo(oxyethylene) chain terminated by an 1-acylamino-1-deoxy-d-sorbitol
unit, and two end-attached lipophilic alkyl chains, have been synthesized by palladium-catalyzed cross-coupling reactions as the key steps. The thermotropic liquid crystalline behavior of these compounds was
investigated by polarized light microscopy, differential scanning calorimetry (DSC), and X-ray scattering.
We investigated the mode of self-organization as a function of the length and position of the lateral polar
chain and the length of the terminal alkyl chains. Depending on the size of the polar and lipophilic segments,
a series of unusual liquid crystalline phases was detected. In three of these phases, the space is divided
into three distinct periodic subspaces. In addition to a hexagonal channeled layer phase (ChL<sub>hex</sub>) consisting
of layers that are penetrated by polar columns, there are also two honeycomb-like network structures formed
by square (Col<sub>squ</sub>/<i>p</i>4<i>mm</i>) or pentagonal cylinders (Col<sub>squ</sub>/<i>p</i>4<i>gm</i>). The cylinder walls consist of the terphenyl
units fused by columns of alkyl chains, and the interior contains the polar side chains. In addition, a hexagonal
columnar phase was observed in which the polar columns are organized in a continuum of terphenyls and
alkyl chains with an organization of the terphenyl cores tangentially around the columns with the long axis
perpendicular to the columns. For one compound, a reversal of birefringence was observed, which is
explained by a reorientation of the terphenyl cores. The addition of protic solvents induces lamellar phases.
2005-11-30 00:00:00
DSC
terphenyl cores tangentially
terminal alkyl chains
alkyl chains
phase