Self-Assembly of Flexible One-Dimensional Coordination Polymers on Metal Surfaces

Abstract

We employed a de novo synthesized porphyrin module to construct one-dimensional (1D) Cu-coordinated polymers on Cu(111) and Ag(111) surfaces. The programmed geometry and functionality of the molecular module together with its conformational flexibility and substrate interaction yields sinuous metal-organic polymeric assemblies, based on an unusual two-fold Cu-pyridyl coordination motif. An analysis of scanning tunneling microscopy (STM) data reveals the occurrence of two enantiomers, resulting from the surface confinement that deconvolutes the module in 2D-chiral conformational isomers. The stereoisomers exhibit site-specific surface anchoring, from whence three discrete orientations are possible for each species. Their sequence and mutual arrangement determine direction and curvature of the metal-organic chains. The Cu-coordinated polymers are very similar on both Cu(111) and Ag(111), where their formation is induced by intrinsic and coevaporated adatoms, respectively, which indicates that the lateral bonding motif is predominantly independent of the substrate. In addition, molecular manipulation experiments show the collective motion of entire segments of the Cu-coordinated multi-porphyrin polymers.

Temperature-dependent self-assembly of NC–Ph5–CN molecules on Cu(111)

“…An interaction driven by a charge transfer from/to the substrate can be the origin of the repulsion between the chains, as already reported for other one dimensional molecular systems. 25,[48][49][50] A surface state mediated interaction, observed for different adatoms on Cu(111) 51,52 or for pentacene molecules on Cu(110), 53 seems not to be pertinent here, since we find a coverage-dependent average distance between the chains.…”

“…The adatom concentration results from an equilibrium between detachment and attachment processes from kink sites, and depends on the temperature, on the energy barrier for detachment and diffusion, and on the step and kink density. Formation of Cu-coordinated bonds for deposition 12,15,18,25,43 or annealing 17,28 at room temperature has been reported for several kinds of molecules on Cu(111).…”

“…14,22,23 At sufficiently high temperature, however, copper substrates can spontaneously supply adatoms for coordination, as reported for molecules containing pyridyl groups on Cu(100) 13,24 and on Cu(111). 15,[25][26][27] On Cu(111), Cu coordination or hydrogen bond formation occurs depending on deposition temperature for a N-substituted derivative of pyrene, 28,29 for molecules containing pyridyl groups, 26 and for a carbonitrile-modified anthracene species. 17 The question whether the molecules may play an active role in the atom detachment from steps has emerged.…”

Manipulating the Conformation of Single Organometallic Chains on Au(111)

“…[14][15][16][17] This is mainly due to the difficulties in depositing such large molecules on surfaces in a clean and intact fashion, 18 and hence alternative strategies such as the on-surface formation of organometallic [19][20][21] or covalently bonded structures 22 are utilized. Although the adsorption geometry of monomers within a Cucoordinated polymer has been studied, 23 no details of the manipulation of the conformational structure of a molecular chain or the interaction between the conformation of the chain and its overall shape has been reported upon. Here we investigate the structure and conformations of a flexible self-assembled molecular chain formed from metal organic linkages between gold atoms and precursor monomer units.…”

Recent Progress in the Fabrication of Low Dimensional Nanostructures via Surface-Assisted Transforming and Coupling

“…Likewise, the defined -conjugated two-dimensional network was realized after the optimization of the 2D Glaser coupling [28], while the precursor with more than 3 terminal alkynes is a determined factor. Actually, polymerization reaction is not limited in the C-H bond, and it also occurs in other types of bonds like N-H bond [29,30]. The greatest advantage of dehydrogenation reaction is that the byproduct H atom obtained during the C-H bond dissociation is easy to get rid of as H 2 gas, so the quality of ordered nanostructure is hardly affected by H atom.…”