An artificial muscle model unit based on inorganic nanosheet sliding by photochemical reaction

Abstract

From the viewpoint of developing photoresponsive supramolecular systems in microenvironments to exhibit more sophisticated photo-functions even at the macroscopic level, inorganic/organic hybrid compounds based on clay or niobate nanosheets as the microenvironments were prepared, characterized, and examined for their photoreactions. We show here a novel type of artificial muscle model unit having much similarity with that in natural muscle fibrils. Upon photoirradiation, the organic/inorganic hybrid nanosheets reversibly slide horizontally on a giant scale, and the interlayer spaces in the layered hybrid structure shrink and expand vertically. In particular, our layered hybrid molecular system exhibits a macroscopic morphological change on a giant scale (~1500 nm) compared with the molecular size of ~1 nm, based on a reversible sliding mechanism.

Photo‐Switching in a Hybrid Material Made of Magnetic Layered Double Hydroxides Intercalated with Azobenzene Molecules

“…Analogous experiments were carried out with CoAl‐T1 sample deposited as thin film (about 1 μm determined by optical profilometry) on a transparent quartz substrate. In this case, transmission measurements permit registering the optical spectra with higher sensitivity, thus providing a more clear evidence of the spectroscopic changes triggered by UV‐light irradiation . The results obtained are also presented in Figure A and shows the presence of two isosbestic points at 310 and 375 nm, this being compatible again with the occurrence of photoinduced trans to cis isomerization of intercalated T1.…”

“…Among the potential candidates, azobenzenes are arguably the best examples of photo‐switchable molecules as these molecules undergo photo‐induced trans‐cis isomerization in solution upon UV light irradiation . Related, photoresponsive inorganic‐azobenzene nanocomposites have been reported for layered silicates or hexaniobates . Still, the performance of these hybrid solid matrices is generally limited by the restricted switching ability of the intercalated molecules in a confined space and light scattering, that reduces the radiation that the guests can absorb .…”

Stimuli-responsive hybrid materials: breathing in magnetic layered double hydroxides induced by a thermoresponsive molecule

“…Still, the examples of this class are limited to photoresponsive layered silicates 19–23 and their characterization is limited to study the X-ray diffraction patterns and the absorption and fluorescence spectra. 24,25 Recently, Inoue and co-workers reported the only example based on inorganic niobate nanosheets that exhibits macroscopic morphological change originating from reversible photoinduced sliding of the layers.…”

Photochromic Intercalation Compounds

“…Bacause the intercalation of the azo dye into the niobate and titanoniobate is difficult, if compared with that into smectite, due to their higher layer charge densities, pre-intercalation of hexyamine and 1,1'-dimethyl-4,4'-bipyridinium and subsequent guest exchange with the C3F-Azo dye was conducted. The basal spacings of the niobate [174] and the titanoniobate intercalates (from (020) reflection) decreased by a light with shorter wavelength than ca. 370 nm, and increased to the value same before the photoirradiations upon subsequent light irradiation at ca.…”