New cyclic conjugated oligomers were synthesized by polymerizing diphenyldiacetylene, phenylacetylene and diphenylacetylene under high pressure below  1Gpa, and their optical limiting properties were investigated. At a low input fluence, the transmittance of the toluene solution obeyed the Beer-Lambert law. Above the threshold of the input fluence, the transmittance decreased with the input fluence, and the oligomers showed optical limiting properties which were 20 - 40% of that of C₆₀, the material with the best optical limiting property.

Polystyrene-bound C₆₀ was synthesized high pressure polymerization of styrene in the presence of C₆₀. The optical limiting property of the solid product with polystyrene-bound C₆₀ showed the value about five times greater than that of C₆₀ solution.

A unique class of p electron conjugated compounds composed of diphenyldiacetylene oligomer and the derivative of condensed polycyclic aromatic compound with the phenyl group were synthesized with appearance of gas by annealing diphenyldiacetylene under elevated pressure. The dc conductivity of the compound increased from below 10^-15 to 10 Scm^-1 with increasing annealing pressure. The electrorheological effect of the suspension of the compound showed the high-temperature working limit up to 100° C.