Hideko Koshima

Photomechanical bending of trans-4-(dimethylamino)azobenzene microcrystals was observed. Upon UV irradiation, the (001) face of the platelike microcrystals bent quickly in the direction opposite the light source, reaching the maximum deflection after 0.5 s. The microcrystal returned to its initial flat shape 30 s after the illumination was stopped. This mechanical motion was reversible over repeated cycles of UV irradiation. The bending effect was attributed to a gradient in the extent of UV-ind

In the last century, molecular crystals functioned predominantly as a means for determining the molecular structures <i>via</i> X-ray diffraction, albeit as the century came to a close the response of molecular crystals to electric, magnetic, and light fields revealed that the physical properties of molecular crystals were as rich as the diversity of molecules themselves. In this century, the mechanical properties of molecular crystals have continued to enhance our understanding of the colligati

Platelike microcrystals of N-3,5-di-tert-butylsalicylidene-3-nitroaniline repeatedly bend and straighten upon alternate irradiation with UV and visible light. The mechanism of bending was elucidated by X-ray crystallographic analyses before and after photoirradiation.

Despite the fact that acridine (1) and diphenylacetic acid (a) are achiral compounds, a chiral two-component molecular crystal (1·a) in which two molecules are self-assembled in a 1:1 molar ratio by hydrogen bonding crystallizes spontaneously from an acetonitrile solution. The space group is P212121, which is typical chiral space group. Both handed crystals (−)-1·a and (+)-1·a can be prepared as desired on a large scale by seeding. The two phenyl planes and the carboxyl plane of the diphenylacet

Abstract Plate-like microcrystals of a photochromic furylfulgide bend toward the light upon UV irradiation and then straighten upon visible light irradiation. The reversible bending was observed over 200 cycles of alternating irradiation with UV and visible light. The mechanism of bending could be explained by the X-ray crystallographic data.

The photomechanical bending behavior of chiral crystals composed of S- and R-enantiomers of photochromic N-3,5-di-tert-butylsalicylidene-1-phenylethylamine in enol form [enol-(S)-1 and enol-(R)-1] has been compared with that of achiral crystals of the racemic compound [enol-(rac)-1] of S- and R-enantiomers. Both platelike chiral and achiral crystals, a few millimeters in length, exhibited similar reversible bending upon alternate irradiation with ultraviolet (UV) and visible light. The reversibl

Abstract NBS was found to be an efficient catalyst for condensations of indoles with aldehydes or ketones in the absence of solvent.

The photomechanical motion of chiral crystals of trans-azobenzene derivatives with an (S)- and (R)-phenylethylamide group was investigated and compared with a racemic crystal. Changes in the UV/Vis absorption spectra of the powdered crystals before and after UV irradiation were measured by using an optical waveguide spectrometer, showing that the lifetime of the cis-to-trans thermal back-isomerization of the chiral crystals was faster than that of the racemic crystals. Upon UV irradiation, a lon

Photomechanically responsive materials are promising candidates for future smart actuator applications. The photo-responsive behaviors originate from the photoisomerization of photochromic molecules. A typical photochromic compound, azobenzene, has been studied extensively in the solution state and has played a crucial role in the photomechanical behaviors of materials such as polymers and gels, via chemical bridging with their matrix. In contrast to polymers and gels, the photomechanical attrib

Noncentrosymmetic and chiral cocrystals were prepared from 2-amino-3-nitropyridine (2A3NP) and achiral benzenesulfonic acids (Ar-SO3H), which were designed for second-order nonlinear optical materials. Both components are commonly crystallized in 1:1 ionic forms of 2A3NPH+·Ar-SO3-. The molecular packings of cocrystals are controlled by the aromatic−aromatic interactions as well as multidirectional ionic and hydrogen bonds between the 2A3NPH+ cations and the sulfonate anions. The crystal of 2A3NP

Optical rotatory powers of chiral cocrystals formed from the achiral molecules tryptamine and 4-chlorobenzoic acid were determined by the HAUP (high accuracy universal polarimeter) method. These cocrystals belonged to space group P2(1)2(1)2(1), and their absolute configuration was confirmed by the Flack parameter. In the M-crystal, 2-fold helical arrangements are formed in a counterclockwise direction between the two components through the quaternary ammonium salt bridge, hydrogen bond, and the

High frequency mechanical bending of the crystal was achieved based on the photothermal effect upon light irradiation.

A series of noncentrosymmetric cocrystals were prepared from 2-amino-5-nitropyridine (2A5NP) and achiral benzenesulfonic acids (Ar-SO3H), which were designed for nonlinear optical materials. The cocrystals are colorless, and the melting points are fairly high, at around 200 °C. Both components are commonly crystallized in 1:1 ionic forms of 2A5NP+·Ar-SO3-. The crystal of 2A5NP and 3-methyl-4-nitrobenzenesulfonic acid belongs to chiral space group P212121, in which the 2A5NP+ cation and the anion