Magneto-chiral nonlinear optical effect with large anisotropic response in two-dimensional halide perovskite

The chiral organic-inorganic halide perovskites (OIHPs) are vital candidates for superior nonlinear optical (NLO) effects associated with circularly polarized (CP) light. NLO in chiral materials often couples with magnetic dipole (MD) transition, as well as the conventional electric dipole (ED) transition. However, the importance of MD in NLO process of chiral OIHPs has not yet been well recognized. Here, the analysis of second harmonic generation circular dichroism (SHG-CD) provides the direct evidence that the MD contribution leads to a large anisotropic response to CP lights in chiral OIHPs, (R-/S-MBACl)2PbI4. The thin films exhibit great sensitivity to CP lights over a wide wavelength range, and the g-value reaches up to 1.57 at the wavelength where the contribution of MD is maximized. Furthermore, it is also effective as CP light generator, outputting CP-SHG with maximum g-factor of 1.76 upon the stimulation of linearly polarized light. This study deepens the understanding of the magneto-optical NLO processes in chiral systems

Redox-Responsive Chiral Dopant for Quick Electrochemical Color Modulation of Cholesteric Liquid Crystal

Here, we report the first redox-active chiral dopant ^{<i><b>Fc</b></i>}<b>D</b>, which electrically alters its helical twisting power (HTP) for a cholesteric liquid crystalline (LC) medium and quickly changes the reflection color. ^{<i><b>Fc</b></i>}<b>D</b> is composed of an axially chiral binaphthyl unit in conjunction with a redox-active ferrocene unit. A cholesteric LC phase of 4′-pentyloxy-4-cyanobiphenyl, doped with ^{<i><b>Fc</b></i>}<b>D</b> (3.0 mol %), developed a blue reflection color. When nitrosyl tetrafluoroborate, a one-electron oxidant, was added to this cholesteric LC phase, ^{<i><b>Fc</b></i>}<b>D</b> was oxidized to decrease its original HTP value by 13%, so that a green reflection color was developed. In the presence of a supporting electrolyte, the reflection color was electrochemically modulated using a sandwich-type glass cell with indium tin oxide electrodes. In quick response to the applied voltage of +1.5 V, the reflection color changed from blue to green within 0.4 s. When 0 V was applied, the reflection color returned to its original blue color. The ^{<i><b>Fc</b></i>}<b>D</b>-doped cholesteric LC is characterized by its fastest electrochemical response and lowest operating voltage among those reported for electrically driven cholesteric LC devices

Redox-Responsive Chiral Dopant for Quick Electrochemical Color Modulation of Cholesteric Liquid Crystal

Here, we report the first redox-active chiral dopant ^{<i><b>Fc</b></i>}<b>D</b>, which electrically alters its helical twisting power (HTP) for a cholesteric liquid crystalline (LC) medium and quickly changes the reflection color. ^{<i><b>Fc</b></i>}<b>D</b> is composed of an axially chiral binaphthyl unit in conjunction with a redox-active ferrocene unit. A cholesteric LC phase of 4′-pentyloxy-4-cyanobiphenyl, doped with ^{<i><b>Fc</b></i>}<b>D</b> (3.0 mol %), developed a blue reflection color. When nitrosyl tetrafluoroborate, a one-electron oxidant, was added to this cholesteric LC phase, ^{<i><b>Fc</b></i>}<b>D</b> was oxidized to decrease its original HTP value by 13%, so that a green reflection color was developed. In the presence of a supporting electrolyte, the reflection color was electrochemically modulated using a sandwich-type glass cell with indium tin oxide electrodes. In quick response to the applied voltage of +1.5 V, the reflection color changed from blue to green within 0.4 s. When 0 V was applied, the reflection color returned to its original blue color. The ^{<i><b>Fc</b></i>}<b>D</b>-doped cholesteric LC is characterized by its fastest electrochemical response and lowest operating voltage among those reported for electrically driven cholesteric LC devices

Photomodulated Supramolecular Chirality in Achiral Photoresponsive Rodlike Compounds Nanosegregated from the Helical Nanofilaments of Achiral Bent-Core Molecules

We prepared a nonchiral mixture of achiral bent-core molecules and photoresponsive rodlike liquid crystalline (LC) molecules. With the help of the isothermal photochemical nematic (N)-isotropic (Iso) phase transition of the photoresponsive rodlike LC molecules, the corresponding phase transition from a dark conglomerate BX phase to another distinguishable dark conglomerate B4 phase took place in the mixture. A large circular dichroism (CD) signal originating from supramolecular chirality was detected in the initial BX phase. On the other hand, the detected CD signal was decreased in the B4 phase after UV irradiation. Interestingly, the decreased CD signal could be reverted to the initial CD signal with visible irradiation. This chiroptical process revealed in this work was stable and reversible and thus opens up the possibility of practical applications such as rewritable optical storage

Polymer Stabilization of Liquid-Crystal Blue Phase II toward Photonic Crystals

The temperature ranges where a pure simple-cubic blue phase (BPII) emerges are quite narrow compared to the body-centered-cubic BP (BPI) such that the polymer stabilization of BPII is much more difficult. Hence, a polymer-stabilized BPII possessing a wide temperature range has been scarcely reported. Here, we fabricate a polymer-stabilized BPII over a temperature range of 50 °C including room temperature. The fabricated polymer-stabilized BPII is confirmed via polarized optical microscopy, Bragg reflection, and Kossel diagram observations. Furthermore, we demonstrate reflective BP liquid-crystal devices utilizing the reflectance–voltage performance as a potential application of the polymer-stabilized BPII. Our work demonstrates the possibility of practical application of the polymer-stabilized BPII to photonic crystals

Thermodynamically Anchoring-Frustrated Surface to Trigger Bulk Discontinuous Orientational Transition

Surface-specific liquid crystal (LC) nanostructures provide a unique platform for studying surface-wetting phenomena and also for technological applications. The most important studies on LC properties are related to bulk alignment, surface anchoring, and so on. Here, we study an LC system with a nematic liquid crystal (NLC) on a perfluoropolymer-coated substrate, in which a discontinuous bulk orientational transition has recently been found. Using free-energy analysis based on experimental results of the newly-conducted grazing-incidence X-ray diffraction (GI-XRD) measurements, we have confirmed a thermodynamic growth process of smectic liquid crystalline wetting nanosheets on the surface and successfully explained that a frustrated surface of planar and vertical anchoring states accompanied by an elastic energy cost kinetically triggers the bulk reorientation in the first-order manner. This interfacial bottom-up process may offer a general insight into how interfacial hierarchical molecular architectures alter the bulk properties of matter thermodynamically

Comparison of the A-T rich regions and the Bacillus subtilis RNA polymerase binding sites in phage ø29

By using a modification of the BAC spreading method for mounting the DNA for electron microscopy, partial denaturation maps of protein-free ø29 DNA and of ø29 DNA containing protein p3 were obtained. In ø29 P3-DNA1 the protein does not seem to influence the melting of the ends of the molecules. The comparison of the partial denaturation map and the B. subtilis RNA polymerase binding sites indicates that five of the seven early promoters (Al, A2, A3, B2 and C2) are located in A-T rich DNA regions whereas the other two early promoters (Bl and Cl) are located in less A-T rich sites.Peer reviewe

Data Supporting Delayed Fluorescence from Inverted Singlet and Triplet Excited States.xlsx

Data Supporting: Delayed Fluorescence from Inverted Singlet and Triplet Excited States</p