Organic microcrystals ranging from several tens nm to µm in size of several chromophores were successfully prepared by simply dispersing ethanol solutions of compounds into stirred water, i.e. by a reprecipitation method. The size of microcrystals was found to depend on concentration of ethanol solutions, dispersing conditions, temperature and so on.

We have presented a simple technique for the fabrication of nanocrystals of organic molecules and polymers and have shown that it is possible, using the liquid‐phase technique, to fabricate organic nanocrystals ranging in size from 10 nm to 1 μm by manipulating the preparative conditions. In particular, nanocrystals of poly(4‐BCMU) ranging from 20 nm to 350 nm were prepared by controlling the preparation conditions. The main advantages of the liquid‐phase technique are the practicality and suitability of the technique for a wide range of materials. The fabrication of organic nanocrystals, though at a very early stage, seems a promising approach for producing low‐dimensional organic materials and, like inorganic nanocrystals, another important objective for future study would be to incorporate organic nanocrystals into a variety of inorganic and organic media. It is hoped that extensive work will be done on organic nanocrystals to evaluate their potential for electronics and photonics.

Highly oriented polyacetylene was synthesized using nematic liquid crystals as polymerization solvent

The third-order nonlinear optical susceptibility χ(3)(−3ω;ω,ω,ω) of propylmethylpolyazine thin films as measured by the third harmonic generation is reported. The χ(3)(−3ω;ω,ω,ω) values of propylmethylpolyazine that possess statistically alternating methyl and propyl substituents on the carbon atoms along the conjugated chain were found to be 8.0×10−12 esu off resonance at 1.5 μm fundamental radiation. The interesting third-order nonlinear properties presumably originate from the unique periodicity of the main π-electron-conjugated polyazine backbone.

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