Nobuyuki Tamaoki

Fixation of the molecular ordering of cholesteric liquid crystals is essential for use of these materials in color information technology. Methods to achieve this as well as thermal and photochemical control of the cholesteric pitch of the liquid crystals are addressed and applications in rewritable color recording are highlighted. The Figure shows a sample recorded using a laser.

Photoresponsive liquid crystals and organogels are finding increasing application in information technology and photonics. In this tutorial review, the authors describe how weak intermolecular interactions facilitate molecular organization of cholesterol-containing dimesogens to form such materials. Design considerations and photoresponsive properties of both organogels and glassy liquid crystals are discussed and their applications to molecular photonics highlighted. The review will be of value

We synthesized dimesogenic liquid crystals with both cholesterol and azobenzene groups by esterification of 10,12-docosadiynedioic acid or docosanedioic acid with 4-alkyl-4‘-hydroxyazobenzene (or 4-hydroxyazobenzene) and cholesterol and studied the thermal, optical, and glass-forming properties. Especially, we focused on the effect of the length of the alkyl chain substituted on the azobenzene unit and the photochemical isomerization of the azobenzene unit on the properties of the mesophases of

Rewritable full‐color recording is potentially technologically important but has not yet been realized. A cholesteric low‐molecular‐weight compound (see Figure) is presented that, in the form of a thin film, displays iridescent colors at room temperature (see the cover picture of this issue) that can be recorded and erased repeatedly to form images by thermal treatment. magnified image

A new potential utility of glass-forming cholesteric liquid crystal (G-CLC) oligomers for application in tunable solid-state laser is presented. The G-CLC is capable of tuning the photonic band gaps (PBGs) by way of the annealing temperature and preserving the tuned PBGs by a subsequent supercooling treatment. This G-CLC film enables the facile fabrication of a continuously gradated PGB structure and, thus, the continuous tuning of a single laser-emission peak (see figure). Detailed facts of imp

A novel class of photoswitches based on a phenylazothiazole scaffold that undergoes reversible isomerization under visible-light irradiation is reported. The photoswitch, which comprises a thiazole heteroaryl segment directly connected to a phenyl azo chromophore, has very different spectral characteristics, such as a redshifted absorption maximum wavelength and well-separated absorption bands of the <i>trans</i> and <i>cis</i> isomers, than conventional azobenzene and other heteroaryl azo compo

The recording of stable and reversible full-color images in the photon mode is reported here. The material is composed of the dicholesteryl ester shown in the Figure, which, when mixed with a small amount of an azobenzene derivative known to be photochemically isomerizable, is able to record full-color images (see also cover) in the liquid-crystalline phase (at increased temperature) but not in the solid phase (room temperature), where images are stable for at least a year.

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTPolymerization of a Diacetylene Dicholesteryl Ester Having Two Urethanes in Organic Gel StatesNobuyuki Tamaoki, Satoru Shimada, Yuji Okada, Abdelhak Belaissaoui, Grzegorz Kruk, Kiyoshi Yase, and Hiro MatsudaView Author Information National Institute of Materials and Chemical Research, Higashi 1-1, Tsukuba, Ibaraki 305-8565, Japan Cite this: Langmuir 2000, 16, 19, 7545–7547Publication Date (Web):July 28, 2000Publication History Received7 April 2000Revised6

Abstract The synthesis and study of the photo‐ and thermoresponsive behavior of a series of novel trimesogens consisting of a diphenylbutadiene core linked to cholesterol moieties on either side via flexible alkyl chains are reported. These molecules possess the combined glass‐forming properties of bischolesterols and the photochromic and luminescent properties of the butadiene moiety. The pitch of the cholesteric phase of these materials could be continuously varied thermally and photochemicall

Abstract N ‐Isopropylacryamide was copolymerized by free‐radical polymerization with N ‐[2‐(4‐phenylazophenoxy)ethyl]acrylamide derivatives that were substituted at their 4′‐position with ethoxy, methoxyethoxy, or isopropyl units, or with N ‐{2‐[4‐(pyridin‐2‐ylazo)phenoxy]ethyl}acrylamide. The polymers were soluble in cold water and possessed lower critical solution temperatures (LCSTs). The value of the LCST rose a few degrees after UV irradiation and dropped after irradiation with visible ligh

Abstract This Review focuses on recent advancements regarding the design of photoisomerizable chiral dopants which can switch the helical orientation in cholesteric liquid crystals upon light stimuli. Chiral dopants exhibiting conformational change in response to an external stimulus can provide dynamic control of the cholesteric pitch. Development of such responsive systems has been attempted since the 1970s. However, major advances on efficient chiral dopants exhibiting either high helical twi

The effects of small amounts of achiral photochromic dopants, 4,4′-di-n-alkylazobenzenes, with various lengths of substituted alkyl chain (CnH2n + 1 ∶ n = 4, 7, 11, 12, 13, 14, 15, 16) on the helical pitch of a cholesteric liquid crystal (CLC) with ca. 1000 molecular weight were investigated in order to utilise the cholesteric reflected colour of these combinations for a rewritable colour image recording. The (E)-azobenzenes (~2 wt%) in the host CLC induced pitch changes dependent on temperature

Thermal, photooptical as well as glass-forming properties of a series of photoresponsive chiral dimesogenic compounds containing cholesterol–azobenzene moieties linked to varying alkyl chain lengths (6–14) are described. All compounds except the dimesogen containing 7 methylene spacers show a cholesteric phase. Selective reflections observed in the cholesteric liquid crystals were found to be blue shifted upon increasing the temperature due to variations in smectic fluctuations. X-Ray diffractio

Herein we report a group of five planar chiral molecules as photon-mode chiral switches for the reversible control of the self-assembled superstructures of doped chiral nematic liquid crystals. The chiral switches are composed of an asymmetrically substituted aromatic moiety and a photoisomerizing azobenzene unit connected in a cyclic manner through methylene spacers of varying lengths. All the molecules show conformational restriction in the rotation of the asymmetrically substituted aromatic m