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Three-dimensional periodic structures of synthetic opals and various inverse opals with interconnected regular array of nano-scale voids in which liquids and liquid crystals can be infiltrated have been prepared for the study of liquids and liquid crystals confined in nano-scale spaces. One-dimensional periodic structure containing a defect layer in which liquids and liquid crystals can be introduced have also been prepared by the multi-layered Si[O.sub.2] and Ti[O.sub.2] stacks. These three-dimensional and one-dimensional periodic structures containing liquids and liquid crystals exhibited novel properties as tunable photonic crystals. Utilizing these phenomena a simple apparatus to evaluate the refractive index of liquids precisely have been proposed, with which sorts of dielectric liquids can be distinguished. Kerr effect and non-linear optical effects of liquids contained in the defect layer of the one-dimensional systems have also been discussed. When the opals and inverse opals contain liquid crystals, the transmission dip and reflection peak wavelengths can be tuned by applied field. The response characteristics are different for opals and inverse opals, which can he interpreted by taking the interaction of liquid crystal molecules with the inner surface of the void into consideration. Utilizing one-dimensional systems containing liquid crystals in the defect layer a ultra-fast switching of a laser light and also in systems containing liquid crystals and fluorescent dyes a voltage tunable lasing in the wide spectral range have been demonstrated. Index Terms--Liquids, liquid crystals, periodic structures, carbon, electrooptic effects, nanostructures, photonic crystals.

Molecular modeling is demonstrated to seek a stable conformation of polydiacetylene (PDA) prepared from [G.sub.n]S in the gel state which is useful in predicting the effective conjugation length in PDA. These findings are useful in the design of PDA-based sensors for organic and biomolecular objectives.

We have studied the preparation of hybrid organic-inorganic polymers and the fabrication of distributed feedback grating using those hybrid polymers. The hybrid polymer precursors were prepared from ester-modified silicon alkoxide by using sol-gel technique. The gel precursor can be then polymerized into a solid film by photo-polymerization. The gratings were fabricated by interference laser technique by employing Lloyd's mirror configuration. The Atomic Force Microscopy (AFM) image shows the formation of corrugated grating structure. Although the grating depth is relatively shallow compared to the thickness of the layer, the photo-pumped lasing action has been observed in those structures. In a film without grating structure, only Amplified Spontaneous Emission (ASE) was observed. [ABSTRACT FROM AUTHOR]

8-quinolinol/copper(II)-, palladium(II)-, and platinum(II)-chelate-based organogelators (1 M) and their nongelling reference compounds (2 M) were synthesized. Complexes 1 M could gelate various organic solvents at very low concentrations. Electron microscope measurements gave visual images of well-developed fibrous structures characteristic of low-molecular-weight organogels. UV/Vis and FTIR spectroscopy revealed that the good gelation ability of 1 M arises from the pi-pi interactions of the chelate moieties and the hydrogen-bond interactions among the amide groups. Very interestingly, field emission performances of the nanofibers prepared from the 1 M gels are evidently different depending on the electronic states of the three kinds of central metals. In addition, the 1 Pt gel shows unique thermo- and solvatochromism of visible and phosphorescent color in response to a sol-gel phase transition. Furthermore, the 1 Pt gel possesses an attractive ability to inhibit dioxygen quenching of excited triplet states, which increases the phosphorescence quantum yield of this gel. This effect is attributed to the isolation effect of the phosphorescent chelate moiety from the dioxygen-containing solution phase.