Remote‐Controllable Molecular Knob in the Mesomorphic Helical Superstructures

Abstract

A programed light‐responsive chiral liquid crystal (LC) containing four photochromic azobenzene moieties covalently connected to a central bicyclic chiral core (abbreviated as AZ4ICD) is newly designed, precisely synthesized, and efficiently applied as a remote‐controllable molecular knob for the optically tunable thin film. First of all, phase evolutions and ordered structures of AZ4ICD are systematically investigated by a combination of thermal, microscopic, scattering, and simulation techniques. Wide‐angle X‐ray diffractions of oriented AZ4ICD samples indicate that the AZ4ICD molecule itself basically forms layer structures: one is a low‐ordered chiral smectic A LC phase (SmA*) with 5.61 nm layer periodicity at high temperatures, and two highly ordered smectic crystal (SmCr1 and SmCr2) phases are subsequently formed at lower temperatures with the anticlinically tilted molecular packing structures. The helical superstructures of chiral nematic LC phase (N*) can be spontaneously constructed by doping AZ4ICD chiral agents into the achiral nematic molecules. Due to the bent conformational geometry of AZ4ICD, the thermal window of blue LC phase (BP) is expanded by stabilizing the double twisted cylindrical building blocks. Remote‐controllable phase transformations in the mesomorphic helical superstructures are demonstrated by tuning the wavelength of light.

Asymmetric Fullerene Nanosurfactant: Interface Engineering for Automatic Molecular Alignments

“…The enhancement of intermolecular interactions between nanoparticles and LC molecules achieved by chemical modification does not necessarily result in the materials with maximally improved physical properties, since functional groups on the nanoparticle surface are randomly distributed . Thus, materials with poorly defined structures and morphologies can limit the formation of uniform LC alignment . To keep pace with the rapid changes in the ever‐growing sophistication of molecular design, chemical functions should be introduced into nanoparticles in a programmed manner .…”

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

“…Therefore, the partially interdigitated dimeric building bock should be tilted with respect to layer normal direction. [17] On the quadrants, two pairs of diffused diffraction arcs indicating the lateralm olecular packing are observed at 2q = 19.88 (d-spacing = 0.44 nm), which is AE 628 away from the equator.I ts trongly supports the fact that the bilayered building block is tilted 288 away from the layer normal direction. On the meridian, the diffraction peaks at 2q = 18.628,2 2.588,a nd 27.268 (d-spacing = 0.48, 0.39, and 0.32 nm) include the lateral molecular packing information in the hierarchical crystalline superstructure with long-range positional order.T he diffraction at 2q = 27.268 detected on the meridian is due to the p-p interaction of pyrenes and the directiono fp-p interaction of pyrenes is perpendicular to layer normal direction.…”

“…It means that layer normal direction is perpendicular to SD and the building block should consist of two PD molecules due to the measured layer spacing ( L= 6.6 nm) considerably larger than the calculated PD length ( l =4.3 nm). Therefore, the partially interdigitated dimeric building bock should be tilted with respect to layer normal direction . On the quadrants, two pairs of diffused diffraction arcs indicating the lateral molecular packing are observed at 2 θ =19.8° ( d ‐spacing=0.44 nm), which is ±62° away from the equator.…”

Programmed Hierarchical Hybrid Nanostructures from Fullerene‐Dendrons and Pyrene‐Dendrons

“…SAXS pattern ( Figure a) indicates that there are three‐layered superstructures with different layers ( d = 8.7, 7.1, and 6.58 nm). The diffraction for d = 7.1 nm can be indexed as (001) plane due to its higher order peaks with d = 3.5 and 2.35 nm (assigned to (002) and (003) planes, respectively) . Although higher order diffractions of all layered superstructures cannot be clearly detected due to overlapped peaks, the existence of other two‐layered structures ( d = 8.7 and 6.58 nm) was identified by TEM images of C 60 D·PD (1:1 complex).…”