Tunable High-Pressure Field Operating on a Cationic Biphenyl Derivative Intercalated in Clay Minerals.

We propose a methodology for applying a pseudo uniaxial pressure to an organic molecule under ordinary temperature and pressure, namely by intercalation into smectites. The pseudo pressure on a biphenyl derivative (BP) was estimated from the averaged dihedral angle around the central bond of BP. In a high hydrostatic pressure field, biphenyl takes a planar conformation. In the interlayer space of synthetic saponite (SSA), the averaged dihedral angle of BP at a loading level of 27% versus the cation exchange capacity was ~26.3°, which indicates that the pseudo pressure applied to BP in the SSA interlayer space corresponds to 0.99 GPa. The high pseudo-pressure field in the interlayer space of SSA was also confirmed by absorption measurements. The dihedral angle around the central bond of the biphenyl moiety decreased to enhance the planarity of the molecule, mainly in response to the electrostatic force that operates between the negatively charged SSA layer and the interlayer cation. The pseudo pressure operating on BP in the smectite interlayer space could be controlled by varying the smectite layer charge density and/or the BP loading level. By using this methodology, controllable pseudo high-pressure properties of organic molecules can be obtained at ordinary temperatures and pressures.

The size control of nano-cluster formed on an inorganic nanosheet/cationic organic molecule hybrid Langmuir-Blodgett film.

Organic molecules adsorbed on an inorganic nanosheet often form a nanometer-sized cluster. In this study, we propose novel strategy for controlling the cluster size. We fabricated hybrid Langmuir-Blodgett (LB) films consisting of N-n-octadecyl-4-[2-(4-dimethylaminophenyl)ethenyl]-pyridinium bromide and a clay mineral, sodium montmorillonite, with varying subphase temperature. As a result, the size of the clusters was found to be decreased from 300 nm to 50 nm by increasing the subphase temperature from 10 degrees C to 40 degrees C.

Incorporation of cationic electron donor of Ni-pyridyltetrathiafulvalene with anionic electron acceptor of polyoxometalate.

A new salt-[Ni(II)(DMSO)(5)(TTFPy)](2)[α-SiW(12)O(40)] (1)-based on polyoxometalates was prepared by coordinating a cationic electron donor of pyridyltetrathiafulvalene (TTFPy) with Ni(II). Although the TTFPy molecule did not form a salt with the anionic α-[SiW(VI)(12)O(40)](4-) because of the weak charge-transfer (CT) interaction, the coordination of Ni with the pyridyl moiety permitted salt formation driven by electrostatic interaction, giving a single crystal of 1. Crystallographic analysis, UV-vis and IR spectroscopy and electrochemical characterization revealed that the fully oxidized α-[SiW(VI)(12)O(40)](4-) was crystallized with the neutral TTFPy moiety from the acetonitrile solution because of the low electron-withdrawing ability of α-[SiW(VI)(12)O(40)](4-), forming a brown-orange crystal. The crystal colour quickly turned to black by immersing in methanol, due to CT from TTF moiety to α-[SiW(VI)(12)O(40)](4-), which was caused by the solvent effect. Increase in the solvent acceptor number from 18.9 for acetonitrile to 41.3 for methanol resulted in the enhancement of the electron withdrawing ability of α-[SiW(VI)(12)O(40)](4-) by 0.317 V in methanol.

Efficient nonlinear optical properties of dyes confined in interlayer nanospaces of clay minerals.

Nonlinear optical (NLO) responses from organic dyes can be maximized when the dyes are aligned in appropriate manners in bulk materials. The use of restricted nanospaces provided by interlayer spacing of inorganic layered materials is a promising strategy for imposing suitable molecular alignments for NLO materials on dyes. The hybrid materials thus obtained exhibit salient NLO responses owing to the improved molecular orientation. In some cases, extension of the π-electron system as a consequence of improved molecular planarity, obtained by the intercalation of a dye into the 2-dimensional interlayer space of an inorganic layered material, is also observed as a factor that enhances NLO responses of chromophores at the molecular level. This review focuses on recent progress in the strategies for controlling the molecular orientation of NLO-phores by employing clay minerals, which are one of the typical inorganic layered materials. In addition, development of a means for fabricating composites that satisfy the properties of an optical material, such as a sufficient size and thickness, a flat surface, and low light-scattering characteristics is required to utilize the superior NLO properties observed for clay/dye hybrid materials for practical applications. A novel means for obtaining such a hybrid material is also outlined.