Manifestation of a Chiral Smectic C Phase in Diphenylbutadiene‐Cored Bolaamphiphilic Sugars

Abstract

A series of symmetrical bolaamphiphiles possessing a diphenylbutadiene core and glucopyranoside head groups linked together by oligomethylene spacers, were synthesized and their thermotropic liquid crystalline properties investigated by polarized light optical microscopy, differential scanning calorimetry, X‐ray diffraction and electro‐optic switching. In spite of the presence of chiral centers, amphiphilic sugars in general do not exhibit macroscopic chirality and this phenomenon is attributed to strong hydrogen bonding between sugar head groups resulting in microphase‐segregated layer like arrangements. In the present study all the molecules investigated exhibited the smectic C* phase, i.e., tilted lamellar phase with macroscopic chiral ordering of the molecules. The stability of this phase increased with increase in the length of the oligomethylene spacers. Whereas for derivatives with spacers containing ≤4 methylene groups, the smectic C* phase was observed only in the cooling phase, for those containing spacers with ≥5 methylene groups this phase was observed both in the heating and cooling cycles. The absorption and fluorescence spectra of these materials suggest that the unusual observation of macroscopic chirality in these bolaamphiphiles containing free hydroxyl groups could be attributed to self‐aggregating behavior of the diphenylbutadiene core.

From Smart Denpols to Remote‐Controllable Actuators: Hierarchical Superstructures of Azobenzene‐Based Polynorbornenes

“…Below the isotropization temperature, the 1D SAXS pattern exhibited a sharp reflection peak with d = 6.41 nm at 135 °C, along with its higher order peaks (Figure b). The q ‐value ratio of 1:2:3 indicates the formation of a layered mesomorphic superstructure . When the temperature reached 115 °C, AZ 3 P denpol still maintained a low‐ordered mesophase, confirmed by the observation of a broad scattering halo in the wide‐angle region (Figure c).…”

Biomolecule assisted self-assembly of π-conjugated oligomers

“…21). 59 The compounds were investigated with respect to thermotropic liquid crystalline properties by POM, DSC, X-ray diffraction and electro-optic switching. Normally, despite the presence of chiral centers in such amphiphilc sugars, these hybrids do not exhibit macroscopic chirality.…”

“…21 The molecular structure of glucopyranoside-substituted diphenylbutadienes (17). 59 The compounds' self-assembly properties were investigated both in the bulk state and in aqueous solution. In the bulk, compounds comprising a short hydrophobic tail (21) were shown to self-assemble into a columnar structure with a carbohydratecoated surface (Fig.…”

Recent advances in the mixed systems of bolaamphiphiles and oppositely charged conventional surfactants

“…This usually cannot be achieved in simple conventional surfactant systems. So far, various self-assembled structures, including nanofibers [15][16][17][18], nanotubes [19][20][21], ribbons [22], cylinders [23], disks [24], vesicles [25][26][27], as well as hydrogels [28][29][30] and liquid crystals [31][32][33], have been fabricated in bola systems. In addition, bolaamphiphiles were also used in template synthesis [34][35][36].…”