Synthesis and photoluminescence of liquid crystalline poly(1-alkynes)

Liquid crystalline poly(1-alkynes) with different functional bridges and lengths of alkyl spacer {-[HC=C(CH₂)₃O-Biph-OCO(CH₂)₁₀CH ₃]_n- [1(3); Biph=4,4′-biphenyl] and -[HC=C(CH₂)_mOCO-Biph-OCO(CH₂)₁₀CH ₃]_n-[2(m); m=3, 4]} are synthesized in high yields (up to 84%) by WCl₆-Ph₄Sn catalyst in dioxane at 60 °C. Polymer 1(3) shows atypical SmA texture. Focal-conic textures of SmA phase are, however, observed in 2(m). Whereas 1(3) emits weakly at 367 nm, intense blue emissions (λ_max∼350 nm) are observed in 2(m), whose intensity increases with the spacer length.