title: A New Solution to an Old Problem: Synthesis of Unsubstituted Poly(para-phenylene).
abstract: Unsubstituted and structurally well-defined poly(para-phenylene) (PPP) has been long-desired as an organic semiconductor prototype of conjugated polymers. To date, several attempts to synthesize unsubstituted, pristine, high-molecular-weight PPP have failed. Here we solved this synthetic problem by a versatile precursor route. Suzuki polymerization of kinked disubstituted 1,4-dimethoxycyclohexadienylene monomers yielded a well-soluble, nonaromatic precursor polymer. Its solubility allowed processing by spin-coating into nanometer-thick films. Subsequent additive-free thermal treatment induced aromatization and led to exclusively para-connected, highly fluorescent PPP with a length of about 75 phenylene units.
authors.affiliation: InnovationLab , Speyererstr. 4, 69115 Heidelberg, Germany.|Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany.|Max Planck Institute for Polymer Research , Ackermannweg 10, 5128 Mainz, Germany.
authors.forename: Ali
authors.initials: A
authors.lastname: Abdulkarim
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany.|Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Hinkel
authors.affiliation: InnovationLab , Speyererstr. 4, 69115 Heidelberg, Germany.|Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Jänsch
authors.affiliation: InnovationLab , Speyererstr. 4, 69115 Heidelberg, Germany.|Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Freudenberg
authors.affiliation: InnovationLab , Speyererstr. 4, 69115 Heidelberg, Germany.|Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg , 69120 Heidelberg, Germany.|Max Planck Institute for Polymer Research , Ackermannweg 10, 5128 Mainz, Germany.
authors.forename: Florian E
authors.initials: FE
authors.lastname: Golling
authors.affiliation: Max Planck Institute for Polymer Research , Ackermannweg 10, 5128 Mainz, Germany.
authors.forename: Klaus
authors.identifier: 0000-0001-6630-8786
authors.initials: K
authors.lastname: Müllen