Tsuneo Kuwahara

Photoisomerization of indolinespirobenzopyran in anionic clay matrices of layered double hydroxides

Sulfonated indolinespirobenzopyran (SP–SO3–) was intercalated into the Mg/Al or Zn/Al layered double hydroxides (LDHs) in the presence of toluene-p-sulfonic acid (PTS). The new intercalates exhibited reversible photoisomerization between SP–SO3– and merocyanine (MC). The presence of PTS was critical for the reversible photoisomerization. MC was very stable and the rate constant of decolorization was <9 × 10–7S–1. SP interacted with non-polar portions between the layers although MC interacted with the polar interior surface of the LDH.

Intercalation of colored organic anions into insulator host lattices of layered double hydroxides

Abstract Colored organic anions such as tetra (4-carboxyphenyl)porphyrin (TPP-C), tetra(4-sulfonatophenyl)porphyrin (TPP-S), tetracarboxyphthalocyaninato cobalt (TPC-C) and others were intercalated into the Mg Al and Zn Al layered double hydroxides (LDHs). After the intercalation of organic anions, interlayer spacing of the LDHs increased to 7.8–30.7 A depending on the amounts of intercalated anions and the sizes of these anions. The amounts of intercalated organic anions reached 48–100% of the exchange capacity of the Zn Al LDH. Absorption maxima of TPP-C and TPP-S intercalates were from 439 to 445 nm and longer than 414 to 420 nm, respectively, of TPP-C and TPP-S alone in solvents.

Photochromism of spiropyran dye in LiAl layered double hydroxide

Sulfonated spiropyran dye (SP) intercalated into the interlayers of a LiAl layered double hydroxide (LDH) showed reversible photochromism even in the absence of co-intercalated organic acid. Photochromic intercalation compounds containing SP and p-toluenesulfonate (PTS) in a LiAl LDH revealed peak sharpening and peak separation in the absorption spectrum. Fluorescence intensity of SP intercalate increased in the presence of PTS indicating that the interaction between SP molecules is weak.

Preparation and photochromism of sulfonated spiropyran-silica nanocomposites

Reversible and stable photochromic properties of sulfonated spiropyran (SP-SO3−) were achieved by trapping SP-SO3− in a silica matrix by the sol-gel route. The presence of organic anions was essential for the photochromic properties, indicating the importance of the coexistence of polar and non-polar regions. The half-life time (t1/2) of the photoinduced merocyanine (MC) trapped in the silica matrix in the presence of dodecylbenzenesulfonic acid (DBS) was larger than 30 days (k<2.7 × 10−7 s−1). The reversibility of SP-SO3− was improved by the addition of triplet quenchers such as benzophenone, naphthalene and anthracene.

Photoisomerization of indolinespirobenzopyran in layered double hydroxides

Sulfonated Indolinespirobenzopyran (SP-SO3–) and toluene-p-sulfonic acid were co-intercalated into a layered double hydroxide. The new intercalate exhibited photochromic properties; reversible photoisomerization between SP-SO3– and photoinduced merocyanine was attained and photoinduced merocyanine was thermally very stable.

Intercalation of organic dyes in the layered host lattice V2O5

Abstract New methyl yellow/V 2 O 5 intercalation compounds were prepared through the exfoliation/restacking method. Though Li-intercalated V 2 O 5 had no clear order structure, the methyl-yellow-intercalated V 2 O 5 had a layered structure, and interlayer spacing increased to 1.38 nm from 0.44 nm for V 2 O 5 .

Thermal characterization of the intercalation compound ofp-toluenesulfonate into a layered double hydroxide

On intercalation ofp-toluenesulfonate (PTS) into Mg/Al (0.73/0.27) layered double hydroxide (LDH), the layer expanded from 4.77 Å to 17.7 Å, indicating that the plane of PTS was perpendicular to the plane of the LDH layers. Thermal treatment of the PTS intercalate resulted in 82% of the included PTS being evolved as decomposition products. This value was higher than the value of 32.5% obtained with sodium PTS and 43.8% with a mixed sample of PTS and Mg/Al (0.73/0.27) LDH. It was considered that the intercalated PTS in Mg/Al (0.73/0.27) LDH was easy to decompose because interaction between intercalated PTS and Mg/Al (0.73/0.27) LDH was smaller than that between sodium and PTS in sodium PTS.