Steering Effect of Bromine on Intermolecular Dehydrogenation Coupling of Poly(p-phenylene) on Cu(111)

Abstract

Among the multitudinous methodologies to steer on-surface reactions, less attention has been paid to the effect of externally introduced halogen atoms. Herein, highly selective trans-dehydrogenation coupling at the specific meta-C−H site of two poly(p-phenylene) molecules, p-quaterphenyl (Ph 4 ) and p-quinquephenyl (Ph 5 ), is achieved on Cu(111) by externally introduced bromine atoms. Scanning tunneling microscopy/ spectroscopy experiments reveal that the formed molecular assembly structure at a stoichiometric ratio of 4:1 for Br to Ph 4 or 5:1 for Br to Ph 5 can efficiently promote the reactive collision probability to trigger the trans-coupling reaction at the meta-C−H site between two neighboring Ph 4 or Ph 5 molecules, leading to an increase in the coupling selectivity. Such Br atoms can also affect the electronic structure and adsorption stability of the reacting molecules. It is conceptually demonstrated that externally introduced halogen atoms, which can provide an adjustable halogen-to-precursor stoichiometry, can be employed to efficiently steer on-surface reactions.

Spatially resolved and quantitatively revealed charge transfer between single atoms and catalyst supports

“…Lin et al 119 reported that the introduced Br atoms on Cu(111) promoted the selectivity toward the coupling reaction of pquaterphenyl (Ph 4 ) and p-quinquephenyl (Ph 5 ). The coassembly of the Br atoms and Ph 4 /Ph 5 with a specic ratio can efficiently increase their collision probability between two neighbouring Ph4 or Ph5 molecules (Fig.…”

“…(f) dI/ dV spectra sampled at the sites highlighted by the coloured dots in (e). Reproduced with permission (d-f) 119. Copyright 2020, American Chemical Society.…”

Anchoring and Reacting On-Surface to Achieve Programmability

“… 34 Nevertheless, the role of the on-surface residue could be much more complicated as demonstrated in some recent works which present enhanced chemical selectivity with the assistance of leaving groups such as halogens. 35 , 36 …”

Vapor-solid interfacial reaction and polymerization for wafer-scale uniform and ultrathin two-dimensional organic films

“…Various methods, including physical vapor deposition and solution-or interface-based methods, have been employed in fabricating low-dimensional organic materials such as individual crystals at nanometer or micrometer length scale [10][11][12][13][14], or two-dimensional (2D) organic thin films, which are important for many applications, including organic field-effect-transistors [5,8] and organic light-emitting diodes [9]. Generally, these methods can be grouped into two in terms of the interactions involved in the process.…”