Decarboxylative Polymerization of 2,6-Naphthalenedicarboxylic Acid at Surfaces

Gao HY, P. Held PA, Knor M, Mück-Lichtenfeld C, Neugebauer J, Studer A, Fuchs H

Abstract

Metal catalyzed polymerization of 2,6-naphthalenedicarboxylic acid (NDCA) to form poly-2,6-naphthalenes at various surfaces is reported. Polymeriza-tions occur via initial formal dehydrogenation of self-assembled diacids to give polymeric bisnaphthyl-Cu-species at elevated temperature as intermediate structures (<160 °C). Further temperature increase eventually leads to poly-naphthalenes via decarboxylative C-C coupling. It is demonstrated that the Cu(111) surface works most efficiently to conduct such polymerizations as compared to the Au(111), Ag(111), Cu(100) and Cu(110) surfaces. Poly-2,6-naphthalene with a chain length of over 50 nm is obtained by using this approach. The decarboxylative coupling of aromatic diacids is a very promising tool which further enlarges the portfolio of reactions allowing for on-surface polymerizations and novel organometallic systems preparations.