Spontaneous Chiral Induction in a Cubic Phase

Abstract

The optical property and the molecular packing structure of achiral bent-rod-shaped liquid crystalline compound 1 possessing an amide group and a flexible spacer were investigated by polarized optical microscopy (POM), circular dichroism (CD) spectroscopy, and X-ray diffraction (XRD). The molecules generated highly ordered liquid crystal phases by lateral intermolecular hydrogen bonds. The cubic phase observed in this study showed a chirality in CD spectroscopy even without the aid of a dopant. Further, its chirality was enhanced by doping with chiral dopant compound 4. The origin of the spontaneous chiral induction was postulated, and the packing structure in the aggregates was proposed.

Double gyroid structures made of asymmetric dimers

“…[33,34] There is also limited number of reports about cubic phases formed by symmetric dimeric molecules with long internal spacer. [35,36] …”

Cubic and Other3DThermotropic Liquid Crystal Phases and Quasicrystals

“…Kajitani et al [148] reported another chiral cubic LC phase formed, surprisingly, spontaneously from the achiral compound 41b (Figure 7.31). Under crossed polarizers, the chiral cubic phase appeared dark.…”

Chirality Synchronization of Hydrogen‐Bonded Complexes of Achiral N‐Heterocycles

“…[3] Nowadays,t he focus has shifted to the spontaneous emergence of homogeneous chirality in ordered assemblies formed in supramolecular systems [4][5][6][7] by bulk crystallization (e.g., Viedma ripening) [8] and the self-assembly of achiral molecules at interfaces [9] and in helical aggregates. [14,21,22] However,i tm ust also be noted that all previously reported molecules forming these symmetry-broken fluids are lipophilic (hydrophobic) molecules combining extended aromatic units with an umber of long aliphatic chains (bent-core mesogens, [12,[15][16][17] 20] di-and oligomesogens, [13, 20] and polycatenar molecules), [14,18,21] which are quite distinct from the molecules expected to have been involved in the chirogenesis of prebiotic aqueous fluids. [14,21] This dynamic route to macroscopic chirality in fluid systems was discussed as af undamentally new source of chirality in prebiotic fluids.…”

“…[14,21] This dynamic route to macroscopic chirality in fluid systems was discussed as af undamentally new source of chirality in prebiotic fluids. [14,21,22] However,i tm ust also be noted that all previously reported molecules forming these symmetry-broken fluids are lipophilic (hydrophobic) molecules combining extended aromatic units with an umber of long aliphatic chains (bent-core mesogens, [12,[15][16][17] 20] di-and oligomesogens, [13, 20] and polycatenar molecules), [14,18,21] which are quite distinct from the molecules expected to have been involved in the chirogenesis of prebiotic aqueous fluids. [22] Herein, we report the first observation of spontaneous macroscopic symmetry breaking in an isotropic mesophase of simple hydrogen-bonding N-heterocycles functionalized with ap olar chain, which renders them compatible with aqueous self-assembly.T hese molecules are based on a4 -phenyl-2,6diamino-1,3,5-triazine core [23] fitted with as ingle tetra(ethylene glycol) chain, which terminates in either am ethoxy group (3a)o ri nahydroxy (3b;S cheme 1).…”