Switching Of Optical Properties Research Articles

Development of Precisely Controlled Structures Containing Main Group Elements for Preparing Superatoms

Abstract This review summarizes our recent studies of main group elements of boron, aluminum, gallium and bismuth units with dendrimer templates. Stepwise assembly of bismuth salts realized tunable photoluminescent materials according to the introduced amounts. Solid-state emission and switching of optical properties were demonstrated by using a shell-effect of the dendrimer. BH3 species placed in the dendrimer acted as a reductant in the nanosized space to form size-controlled metal particles. Atomicity control for AlCl3 or GaCl3 enabled a solution-phase synthesis of superatoms, which have been expected to be new building blocks for materials.

Photochromic coumarin spiropyranes with switching of optical properties by lanthanide ions

Coumarin spiropyrans with terminal carbohydrazide substituents were synthesized. UV irradiation of their solutions was found to initiate rearrangement into a deeply colored merocyanine form. In the presence of lanthanide cations, the obtained spiropyrans exhibited a “naked eye” chromogenic effect, accompanied by a change of the solution color from yellow to violet.

Diarylethene-modified nucleotides for switching optical properties in DNA

Diarylethenes were attached to the 5-position of 2’-deoxyuridine in order to yield three different photochromic nucleosides. All nucleosides were characterized with respect to their absorption and photochromic properties. Based on these results, the most promising photochromic DNA base modification was incorporated into representative oligonucleotides by using automated phosphoramidite chemistry. The switching of optical properties in DNA can be achieved selectively at 310 nm (forward) and 450 nm (backward); both wavelengths are outside the normal nucleic acid absorption range. Moreover, this nucleoside was proven to be photochemically stable and allows switching back and forth several times. These results open the way for the use of diarylethenes as photochromic compounds in DNA-based architectures.

Switching of optical properties in zeolitic nanocomposites

AbstractThe guest molecule azobenzene is aligned nearly perfectly by the channels of the molecular sieve AlPO4‐5. After irradiation with light of the wavelength 360 nm the configuration and the orientation of the molecules are changed. This results in changes of the refractive index. It turns out that this reaction is reversible (back reaction by irradiation with 436 nm) and that the change of the birefringence can be very large (δn' = 0,033). It is demonstrated that a crystal of a thickness of 13 μm is sufficient to be switched between a λ‐plate and a λ/2‐plate. This is an example of an opto‐optical microswitch.

Potential switching of optical properties in polymer electrolytes

The electric field dependence of the optical properties of series of anion-conducting polymer electrolytes at an ITO-electrolyte interface was investigated. A change in reflectance and refractive index of polymer electrolytes [ poly( ethyl methacrylate)] 18 (Bu;jSnX) 3 Bu 4 NX where X = Cl, Br, and SCN was observed. This was ascribed to anion accumulation/depletion in the interfacial region. Shorter response times were observed for electrolytes with higher conductivities, illustrating the interrelationship between these two phenomena.