Liquid crystalline light-emitting thermally stable readily processable substituted polyacetylenes

Mesomorphic and luminescent poly(propiolates) with different skeleton structures (-{(R)CequalsC[CO<SUB>2</SUB>(CH<SUB>2</SUB>)<SUB>6</SUB>OCO-Biph- OC<SUB>7</SUB>H<SUB>15</SUB>]}<SUB>n</SUB>-; R equals H (1), CH<SUB>3</SUB> (2), C<SUB>6</SUB>H<SUB>5</SUB> (3), Biph equals biphenylyl} are synthesized. The backbone absorption in 2 and 3 are weak but upon photoexcitation, the polymers emit strong violet light of 369 nm, whose intensities are higher than that from poly(l-phenyl-l-octyne), a well-known highly-fluorescent polyacetylene. The main chain of 3 absorbs strongly at 380 nm, and the polymer is completely nonluminescent. All the polymers are thermally stable and form enantiotropic monolayer SmA phase, with 1 adopting well-ordered packing arrangements.