On-Surface Formation of One-Dimensional Polyphenylene through Bergman Cyclization

Abstract

On-surface fabrication of covalently interlinked conjugated nanostructures has attracted significant attention, mainly because of the high stability and efficient electron transport ability of these structures. Here, from the interplay of scanning tunneling microscopy imaging and density functional theory calculations, we report for the first time on-surface formation of one-dimensional polyphenylene chains through Bergman cyclization followed by radical polymerization on Cu(110). The formed surface nanostructures were further corroborated by the results for the ex situ-synthesized molecular product after Bergman cyclization. These findings are of particular interest and importance for the construction of molecular electronic nanodevices on surfaces.

Dehydrogenative Homocoupling of Terminal Alkenes on Copper Surfaces: A Route to Dienes

“…Theh igh-resolution submolecularly resolved STM image presented in Figure 2b clearly shows that the dimer structure consists of two bright protrusions which are assigned to the VBP monomers as compared with their STM appearances and dimensions (see Figure S1 in the Supporting Information). Also,inthe middle of the dimer structure asmooth connection (density of states) could be resolved, and should be attributed to the covalent coupling of the alkenyl groups because of the following reasons:1 )the smooth and seamless STM morphology implies the characteristic feature of covalent linkages between organic molecules; [4][5][6][7][8] 2) sincet he alkenyl group of the VBP molecule has al ower density of state,a sr eflected from the STM contrast, it is natural to speculate that the dark connection within the dimer structure should be ascribed to the coupling between alkenyl groups;3 )the covalent coupling between phenyl groups should be ruled out as that reaction would require higher temperatures at about 500 Kon Cu(110) as reported previously. [19] Moreover,acloser inspection of the dimer structure allows us to identify that the two bright protrusions (i.e.d iphenyl groups) are not coaxial and exhibit as taggered arrangement.…”

“…[1][2][3] Generally,t he reactants of these reactions are hydrocarbons functionalized with C À Ho rC À Xg roups (X stands for halogen), and two reactants couple by cleaving either the CÀHo rC À Xb onds and forming an ew carbon-carbon bond with the help of carefully selected catalysts.R ecently,o n-surface chemistry has attracted attention because various well-known chemical reactions have been successfully achieved on surfaces, [4][5][6][7][8][9][10][11][12][13] and more interestingly,some reactions that are hard to mediate by conventional chemistry have also been achieved on surfaces. [14][15][16][17][18][19][20] Specifically,d ehydrogenative coupling of hydrocarbons like alkynes (sp 1 ), [9,21,22] alkanes (sp 3 ), [17,18] and arenes (sp 2 ), [19,20,23] have very recently been introduced onto surfaces with the interest of fabricating novel carbon nanostructures/ nanomaterials or exploring new reaction pathways.T oo ur knowledge,h owever,o n-surface coupling of alkenes (sp 2 ), another important hydrocarbon, has not been reported so far.…”

Recent advances of the Bergman cyclization in polymer science

“…Attempting to resolve the fundamental principles in this field, we published the first report on the on-surface formation of one-dimensional polyphenylene chains through a Bergman cyclization on a Cu(110) surface [30].…”

On‐Surface Formation of Cumulene by Dehalogenative Homocoupling of Alkenyl gem‐Dibromides

“…[1][2][3][4][5][6] In general, most of the on-surface reactions follow pathways different from their counterparts in solution because of the effects of the surface: the reactions are confined in two dimensions and the possible catalytic surface activity. [7][8][9][10][11][12][13][14] Consequently, unexpected reactions have been surprisingly discovered in on-surface synthesis experiments, [15][16][17][18][19][20][21][22] and thus, this strategy has opened up a way for the fabrication of a plethora of novel surface nanostructures which may be hardly obtained by traditional solution methods.…”