Bi-Directional Synthesis of a Series of 2,5-Dodecanoxyphenyleneethynylene Oligomers

A family of rigid rod like 2,5-dodecanoxy-phenyleneethynylene oligomers having 3, 5, 7, and 9 repeating units was selectively synthesized by a bidirectional iterative divergent-convergent approach. Starting from a central 1,4-bis(dodecanoxy)-2,5-diiodobenzene monomer, only two repetitive reactions were involved with each cycle of oligomerization: a Pd/Cu crosscoupling with the bifunctional monomer 1-(3,3-diethyltriazene)-2,5bis(dodecanoxy)-4-(ethynyl)benzene, generating oligomers with terminal triazene groups, followed by a further nucleophilic substitution with iodine.