14 research outputs found
Synthesis of guanidinium–sulfonimide ion pairs: towards novel ionic liquid crystals
The recently introduced concept of ionic liquid crystals (ILCs) with complementary ion pairs, consisting of both, mesogenic cation and anion, was extended from guanidinium sulfonates to guanidinium sulfonimides. In this preliminary study, the synthesis and mesomorphic properties of selected derivatives were described, which provide the first example of an ILC with the sulfonimide anion directly attached to the mesogenic unit
Triphenylene Silanes for Direct Surface Anchoring in Binary Mixed Self-Assembled Monolayers
New triphenylene-based silanes 2-(ω-(chlorodimethylsilyl)-<i>n</i>-alkyl)-3,6,7,10,11-penta-<i>m</i>-alkoxytriphenylene <b>4 (T<i>m</i>-C<i>n</i>)</b> with <i>n</i> = 8 or 9 and <i>m</i> = 7, 8, 9, 10, or 11 were synthesized,
and their self-assembly behavior in the liquid state and at glass
and silicon oxide surfaces was investigated. The mesomorphic properties
of triphenylene silanes <b>4 (T<i>m</i>-C<i>n</i>)</b> and their precursors <b>3 (T<i>m</i>-C<i>n</i>)</b> were determined by differential scanning calorimetry
(DSC), polarizing optical microscopy (POM), and X-ray diffraction.
From the small-angle X-ray scattering (SAXS) regime, a preferential
discotic lamellar mesophase can be deduced, and wide-angle X-ray scattering
(WAXS) highlights the liquid-like characteristics of the alkyl side
chains. To transfer these bulk structural properties to thin films,
self-assembled monolayers (SAMs) were obtained by adsorption from
solution and characterized by water contact angle measurements, null
ellipsometry, and atomic force microscopy (AFM). Employing the concentration
as an additional degree of freedom, binary SAMs of 2-(ω-(chlorodimethylsilyl)-undecyl)-3,6,7,10,11-penta-decyloxytriphenylene <b>4 (T10-C11)</b> were coassembled with chlorodecyldimethylsilane
or chlorodimethyloctadecylsilane, and their capability as model systems
for organic templating was evaluated. The structure of the resulting
binary mixed SAMs was analyzed by water contact angle measurements,
null ellipsometry, and X-ray reflectivity (XRR) in combination with
theoretical modeling by a multidimensional Parratt algorithm and AFM.
The composition dependence of film thickness and roughness can be
explained by a microscopic model including the steric hindrance of
the respective molecular constituents