Alkyl Tail Length Dependence of Structures in a Series of Symmetrically Tapered Bisamides Exhibiting Self‐Assembled Supramolecular Columnar Phases

Phase behaviour and Janus hierarchical supramolecular structures based on asymmetric tapered bisamide

“…[41][42][43] Previously, we have also reported a discotic liquid crystal phase formed by a series of symmetric tapered bisamides (abbreviated as C n PhBA, where n is the number of carbon atoms in each tail, n ¼ 6, 8, 10, 12, 14, and 16) having three alkyl chain tails at each end of the three aromatic ring cores. [44][45][46] A similar molecular architecture has also been reported by Ungar et al 47 From our previous results, four C n PhBA were found to generate a disc-like building block through the intermolecular H-bonding, and the supramolecular discs then further assembled into two oblique columnar phases in response to the environment temperature. With these experiences, we would like to investigate which structures and phase behaviours are altered if the symmetry of the bisamide building molecules is lost and the Janus feature is introduced.…”

“…This observation is similar to that made with the symmetric tapered bisamides reported before. [44][45][46] In C 22 PhBAEO 3 , the peaks of the ( 200) and (110) diffractions gradually merged together and completely overlapped at 82 C, revealing a transition from the crystal to a pseudo-hexagonal rotator phase. This rotator phase has been described such that the alkyl tails rotate along the chain axis locally in the unit cell, in which the all trans-conformation is still kept yet the bond orientation order is lost.…”

“…In the highangle region (>5 ) along the meridian direction, an arc with d-spacing 0.49 nm appeared that corresponds to the bisamide core-to-core distance along the hydrogen bonding direction. [44][45][46] The (200) arc at 2q ¼ 21.2 along the equator and the (110) arc at 2q ¼ 22.8 in the quadrant are attributed to the packing of the tail crystals and their orientation. 60 This is thus a ''fiber pattern'' of the alkyl chain crystals with the b-axis along the fiber (column) direction.…”

“…These discs are then further stacked into a supramolecular asymmetric column and further self-organized into a 3D monoclinic lattice with a bilayer character that is constructed by phase separated hydrophobic and hydrophilic tails. Therefore, instead of oblique LC columnar phases as found in symmetric bisamides, [44][45][46] the asymmetric bisamides formed a 3D long-range ordered hierarchical crystalline structure which can be obtained through moderate temperature annealing.…”

Kinetically Controlled Polymorphic Superstructures of Pyrene‐Based Asymmetric Liquid Crystal Dendron: Relationship Between Hierarchical Superstructures and Photophysical Properties

“…By increasing the PD concentration from 1.9 to 308.8 mm,the entire spectra band above 100 mm is gradually reduced in the saturated region (below 100 mm)d ue to the aggregation-induced quenching. [22] However,c onsidering the ratio between mono- mer band (l = 396 nm) ande xcimer band (l = 446 nm), excimer band do not increase. [22] This result strongly supports the hypothesis that intermolecular H-bonding is the mostc ritical factor for the formation of building blocks rather than the p-p interaction.…”