Preparation of a sulfo-group-containing rod-like polysilsesquioxane with a hexagonally stacked structure and its proton conductivity.

A sulfo-group-containing rod-like polysilsesquioxane with a hexagonally stacked structure (PSQ-SO3H) was successfully prepared by oxidation and hydrolytic polycondensation of 3-mercaptopropyltrimethoxysilane (MPTMS) in a mixed aqueous solution of NaOH and H2O2. The X-ray diffraction pattern of the PSQ-SO3H film exhibited three diffraction peaks with a d-value ratio of 1:1/√3:1/2, indicating the formation of a hexagonally stacked structure. In addition, the transmission electron microscopy image of PSQ-SO3H exhibited a striped pattern, indicating that the rod-like PSQs were stacked in a parallel fashion. The presence of ionic side-chains composed of the sulfonate anions and sodium cations during the hydrolytic polycondensation of MPTMS was found to be essential for the formation of this regularly structured PSQ. Finally, the proton conductivity of the PSQ-SO3H film, determined by using complex impedance spectroscopy, was relatively high (>10(-2) S cm(-1)) at 80 °C and 30-90 % relative humidity.

Behavior of chiral induction from polysilsesquioxanes bearing chiral and ammonium groups to anionic pyrene derivatives.

The behavior of chiral induction from ladder-like polysilsesquioxanes (R60- and S60-PSQs) bearing chiral and ammonium side-chain groups (compositional ratio = ca. 60:40) to the anionic pyrene derivative, 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt (PTSNa4), was investigated. The circular dichroism (CD) spectra of PTSNa4/(R60- and S60-PSQs) mixtures in methanol exhibited reverse peaks at 230-250, 280-290, and 310-370 nm, which were assigned to PTSNa4 and indicated that the achiral PTSNa4 molecule had chirality induced from the chiral PSQs. In addition, it was found that an eximer of PTSNa4 was formed by hybridization with the chiral PSQs, i.e., the emission peaks not only due to a monomer state at 385 and 408 nm but also due to an eximer at 460-520 nm were observed in the fluorescence spectrum excited at 377 nm. This result suggests that the negatively charged PTSNa4 formed an eximer along the positively charged side-chain ammonium groups of PSQs. To investigate the influence of the structures of the pyrene derivatives on chiral induction behavior, the CD measurements of the mixtures of R60- and S60-PSQs in methanol with different pyrene derivative, 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (pyranine), were also performed. It was found that the intensities of the absorptions for the pyanine solutions were lower than those for PTSNa4 solutions. These results suggest that the point-symmetry of the pyrene derivatives influences the level of chiral induction. Therefore, the point-symmetry of pyrene derivatives is an important factor for determining the behavior of chiral induction from chiral PSQs to these compounds.