Monodisperse Poly(triacetylene) Rods: Synthesis of a 11.9 nm Long Molecular Wire and Direct Determination of the Effective Conjugation Length by UV/Vis and Raman Spectroscopies

With 16 C-C double and 32 C-C triple bonds and a length of 11.9 nm, the hexadecameric poly(triacetylene) (PTA) of type 1 is currently the longest linear fully π-conjugated molecular wire that does not contain aromatic repeat units. A series of PTA oligomers 1 extending from monomer to hexadecamer was prepared by a rapid and efficient statistical deprotection-oligomerization sequence; the effective conjugation length at which saturation of molecular properties occurs was determined as n=10 (n=number of monomeric units) by both UV/Vis and Raman spectroscopies.