Synthesis of Cyclic Oligomers of 4,4′′-Diethynyl-4′,5′-dioctyl-o-terphenyl Using Eglington Coupling Reaction: Formation of Large Cyclic Oligomers as Major Products under Standard Conditions

Dimer 2, trimer 3, hexamer 6, octamer 8, and decamer 10 of 4,4′′-diethynyl-4′,5′-dioctyl-o-terphenyl 1 were synthesized by using copper(II) acetate-mediated Eglington coupling reaction of 1 in pyridine or pyridine–methanol. Although dimer 2 and trimer 3 were formed as major products under high dilution conditions, large oligomers such as hexamer 6, octamer 8, and decamer 10 were obtained in moderate total yield under standard Eglington conditions. The MALDI-TOF MS and GPC behavior of large oligomers exhibit the formation of giant macrocycles 3 nm diameter and 2–4 nm long in one-pot procedure.