Fabrication of on-surface molecular electronic devices remains one of the most fascinating goals in the field of nanotechnology.Key challenges lie in controllable construction of nanostructures with molecular precision,efficient electron transportability and high stability.Thus,synthesis of covalently interlinked nanostructures through various kinds of chemical reactions(e.g.,Ullmann reaction,imine coupling,alkyne homo-coupling and dehydrogenation reaction)on surfaces has become one of the most exciting and prosperous subjects in the recent years.Here,from the interplay of scanning tunneling microscopy imaging and density functional theory calculations,(i)we have formed one-dimensional polyphenylene chains through Bergman cyclization followed by radical polymerization on Cu(110);(ii)we have demonstrated the formation of the polyphenylene structure through an unprecedented selective aryl-aryl coupling via direct C-H bond activation of quaterphenyl molecules on Cu(110).