Diarylethenes for Memories and Switches

Fluorogenic and chromogenic chemosensors and reagents for anions.

J-aggregates are of significant interest for organic materials conceived by supramolecular approaches. Their discovery in the 1930s represents one of the most important milestones in dye chemistry as well as the germination of supramolecular chemistry. The intriguing optical properties of J-aggregates (in particular, very narrow red-shifted absorption bands with respect to those of the monomer and their ability to delocalize and migrate excitons) as well as their prospect for applications have motivated scientists to become involved in this field, and numerous contributions have been published. This Review provides an overview on the J-aggregates of a broad variety of dyes (including cyanines, porphyrins, phthalocyanines, and perylene bisimides) created by using supramolecular construction principles, and discusses their optical and photophysical properties as well as their potential applications. Thus, this Review is intended to be of interest to the supramolecular, photochemistry, and materials science communities.

J-aggregates: from serendipitous discovery to supramolecular engineering of functional dye materials.

Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

A superhydrophobic surface is a surface with a water contact angle close to or higher than 150°. In this feature article, we review the historical and present research on superhydrophobic surfaces, including the characterization of superhydrophobicity, different ways to fabricate rough surfaces, and low-surface-energy modifications on inorganic and organic rough surfaces. It is the combination of surface roughness and low-surface-energy modification that leads to superhydrophobicity. Notably, research on superhydrophobic surfaces has not only fundamental interest but various possible functional applications in micro- and nano-materials and devices.

Superhydrophobic surfaces: from structural control to functional application

Near-infrared absorbing dyes

A new class of crown spirobenzopyrans were designed and synthesized. The crown spirobenzopyrans showed thermally irreversible photochromism only in the presence of alkali-metal cations accompanying cation-selective coloring efficiency. Thus, the new crown spirobenzopyrans could transmit information of two different simultaneous stimuli (ion and photon) to changes in their optical properties. The dual-mode signal transducer molecules developed here can be considered to perform “AND” gate type signal transduction based on photochromism of artificial receptors. Molecular recognition abilities and photochromic properties of the new crown spirobenzopyrans were characterized by use of NMR and FAB mass spectroscopies.

New Crown Spirobenzopyrans as Light- and Ion-Responsive Dual-Mode Signal Transducers

A chiral cyclohexane containing two photochromic diarylethene units was synthesized in an attempt to use it as a dopant for a photoresponsive liquid crystal. A stable photoswitching between nematic and cholesteric phases could be induced by the addition of a small amount of the chiral cyclohexane to a nematic liquid crystal 4-cyano-4‘-penthylbiphenyl (K-15).

Hiroyuki Nakazumi

Papers

Near-infrared absorbing dyes

New Crown Spirobenzopyrans as Light- and Ion-Responsive Dual-Mode Signal Transducers

Photoswitching of Helical Twisting Power of a Chiral Diarylethene Dopant: Pitch Change in a Chiral Nematic Liquid Crystal

Molecular Recognition of .beta.-Ribofuranosides by Synthetic Polypyridine-Macrocyclic Receptors

Colorimetric sensing of metal ions by bis(spiropyran) podands: Towards naked-eye detection of alkaline earth metal ions