A series of substituted poly (p-phenylenediyne) s (1a-f) was synthesized by the palladium- catalyzed cross-coupling condensation of terminal dialkynylalkanes with substituted diiodobenzenes. Polymerizations were conducted with 1, 4-diiodo-5-hexoxy-2- methoxybenzene or 1, 4-diiodo-5-hexyl-2-methylbenzene and with 1, 6-hexadiyne, 1, 7- heptadiyne, or 1, 8-octadiyne. Thus, six different poly (p-phenylenediyne) s (1a-f,[ArC⋮ C ( ...