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Bicontinuous and multicontinuous network phases are among nature's most complex structures in soft matter systems. Here, a chiral bicontinuous tetragonal phase is reported as a new stable liquid crystalline intermediate phase at the transition between two cubic phases, the achiral double gyroid and the chiral triple network cubic phase with an I23 space group, both formed by dynamic networks of helices. The mirror symmetry of the double gyroid, representing a meso-structure of two enantiomorphic networks, is broken at the transition to this tetragonal phase by retaining uniform helicity only along one network while losing it along the other one. This leads to a conglomerate of enantiomorphic tetragonal space groups, P41212 and P43212. Phase structures and chirality were analyzed by small-angle X-ray scattering (SAXS), grazing-incidence small-angle X-ray scattering (GISAXS), resonant soft X-ray scattering (RSoXS) at the carbon K-edge, and model-dependent SAXS/RSoXS simulation. Our findings not only lead to a new bicontinuous network-type three-dimensional mesophase but also reveal a mechanism of mirror symmetry breaking in soft matter by partial meso-structure racemization at the transition from enantiophilic to enantiophobic interhelical self-assembly.

A series of achiral tricatenar rod-like molecules with a 3,5-disubstitution pattern at one end and a single alkyl chain at the other end of a rod-like azobenzene derived core is reported. Depending on temperature and alkyl chain length, these Y-shaped compounds self-assemble into different types of liquid crystalline (LC) phases, ranging from non-tilted and synclinic tilted hexatic, via non-tilted and anticlinic tilted smectic and bicontinuous cubic LC phases, to a spontaneous mirror symmetry broken isotropic liquid (Iso1[∗]) or a related achiral liquid network phase (Iso1). An additional tilted, but uniaxial smectic phase was observed at the transition between anticlinic and synclinic tilt correlation and was investigated by soft resonant X-ray scattering with respect to possible helix formation. This work provides a new concept for the design of technological interesting azobenzene based LC materials with anticlinic tilted smectic C phases (SmCa) and with azobenzene units organized in the long range or short range helical network structures of bicontinuous cubic and chiral isotropic liquid phases, respectively. Core fluorination removes all lamellar phases, leaving only the cubic phase over wide temperature ranges, even at ambient temperature. This journal is

Development of new functional materials requires the understanding of the fundamental rules of complex superstructure formation in self-assembling systems. Here we report new liquid crystalline honeycombs based on reticular self-assembly of bolapolyphilic rods with two mutually incompatible and branched side-chains, one a semiperfluorinated, the other one a non-fluorinated alkyl chain, all derived from the chessboard tiling by cell deformation due to distinct modes of tilting of π-conjugated rods within or out of the crystallographic plane. Among them the new square + rhomb tiling and a stretched rectangular "chessboard" tiling, both with alternatingly filled prismatic cells, are constructed. Out of plane tilting leads to cell shrinking and cell deformation. Nonfluorinated polyaromatic cores allow a continuously changing tilt, retaining the square cells by simultaneously tilting all molecules, associated with an inversion of the birefringence via an optically isotropic state. In contrast, fluorinated cores with different discrete face-to-face stacking modes can assume only discrete tilt angles, which provides rectangular cells with only two walls being tilted. The system offers even more phases including single-color cells with sparingly packed "voids" and a three-color rhomb tiling with additional mixed cells. The research uncovers basic rules of reticular self-assembly by formation of soft multi-functional liquid-crystalline materials. [ABSTRACT FROM AUTHOR]

Quasiperiodic patterns and crystals—having long range order without translational symmetry—have fascinated researchers since their discovery. In this study, we report on new p‐terphenyl‐based T‐shaped facial polyphiles with two alkyl end chains and a glycerol‐based hydrogen‐bonded side group that self‐assemble into an aperiodic columnar liquid quasicrystal with 12‐fold symmetry and its periodic liquid‐crystalline approximants with complex superstructures. All represent honeycombs formed by the self‐assembly of the p‐terphenyls, dividing space into prismatic cells with polygonal cross‐sections. In the perspective of tiling patterns, the presence of unique trapezoidal tiles, consisting of three rigid sides formed by the p‐terphenyls and one shorter, incommensurate, and adjustable side by the alkyl end chains, plays a crucial role for these phases. A delicate temperature‐dependent balance between conformational, entropic and space‐filling effects determines the role of the alkyl chains, either as network nodes or trapezoid walls, thus resulting in the order‐disorder transitions associated with emergence of quasiperiodicity. In‐depth analysis suggests a change from a quasiperiodic tiling involving trapezoids to a modified one with a contribution of trapezoid pair fusion. This work paves the way for understanding quasiperiodicity emergence and develops fundamental concepts for its generation by chemical design of non‐spherical molecules, aggregates, and frameworks based on dynamic reticular chemistry. [ABSTRACT FROM AUTHOR]

Novel bolaamphiphilic triblockmolecules consisting of a rigid biphenyl unit, with a polar 2,3-dihydroxypropyloxy group and phenolic OH group at opposite ends, as well as a semiperfluorinated chain in a lateral position is synthesized through palladium catalyzed cross coupling reactions as the key steps. The findings show an unusual phase sequence, where, with respect to the chain length, columnar mesophases occur between two mesophases with layer organization.

Novel complex mesophase morphologies are obtained by careful molecular design. It is shown that it is possible to design complex mesophase morphologies, related to those of multiblock copolymers also with low-molecular mass liquid crystalline (LC) materials.