title: Chiral-Selective Formation of 1D Polymers Based on Ullmann-Type Coupling: The Role of the Metallic Substrate.
abstract: The chiral-selective formation of 1D polymers from a prochiral molecule, namely, 6,12-dibromochrysene in dependence of the type of metal surface is demonstrated by a combined scanning tunneling microscopy and density functional theory study. Deposition of the chosen molecule on Au(111) held at room temperature leads to the formation of a 2D porous molecular network. Upon annealing at 200 °C, an achiral covalently linked polymer is formed on Au(111). On the other hand, a chiral Cu-coordinated polymer is spontaneously formed upon deposition of the molecules on Cu(111) held at room temperature. Importantly, it is found that the chiral-selectivity determines the possibility of obtaining graphene nanoribbons (GNRs). On Au(111), upon annealing at 350 °C or higher cyclo-dehydrogenation occurs transforming the achiral polymer into a GNR. In contrast, the chiral coordination polymer on Cu(111) cannot be converted into a GNR.
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands.
authors.forename: Tuan Anh
authors.initials: TA
authors.lastname: Pham
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands.
authors.forename: Bay V
authors.initials: BV
authors.lastname: Tran
authors.affiliation: Center for Computational Physics, Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan St., Hanoi, Vietnam.
authors.forename: Manh-Thuong
authors.initials: MT
authors.lastname: Nguyen
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands.
authors.forename: Meike
authors.initials: M
authors.lastname: Stöhr
keywords: 1D polymers; Ullmann coupling; chiral selective formation; graphene nanoribbons; on-surface polymerization