Cyclo[n]carbon allotropes built from sp-hybridized carbon atoms have aroused substantial interests, but until now even their structures (i.e., polyynic or cumulenic) and stabilities (i.e., cyclic or linear) are still under debate. Due to their high reactivity, it is rather difficult to synthesize in condensed phase, which hampers further real-space characterizations. Recently, isolated cyclo[18]carbon (C18) and cyclo[16]carbon (C16) molecules were generated on the surface by atom manipulation, which allowed to identify the polyynic structure of C18 and C16. More interestingly, for the smaller cyclo[n]carbon, questions arise: is it still stable in cyclic form? If so, what is the structure? Here, we successfully produce two aromatic cyclocarbons, that is, cyclo[10]carbon (C10) and cyclo[14]carbon (C14), via tip-induced dehalogenation and followed by retro-Bergman reaction of fully chlorinated naphthalene (C10Cl8) and anthracene (C14Cl10) molecules, on a bilayer NaCl/Au(111) surface at 4.7 kelvin. The cumulenic structure of C10 and Peierls-transition intermediate of C14, different from the polyynic structure of C18 and C16, are revealed by bond-resolved atomic force microscopy. Our results demonstrate a universal synthetic strategy to generate aromatic cyclo[n]carbons on the surface, opening an avenue for characterizing a series of annular carbon allotropes for the structure and stability.

Prefabricated construction is an emerging technology in the construction industry, which can effectively meet the construction scale requirements of construction projects. It can also shorten the construction time and reduce unnecessary consumption of construction resources. The introduction of BIM + VR technology into the prefabricated construction industry will improve and improve the construction of the relevant construction industry chain, architectural visualization design, architectural virtualization construction, project cost management, and production operations. In particular, the application of BIM + VR technology to the construction of prefabricated buildings can further refine the entire construction process and improve the overall quality of the project. The application advantages of these two technologies are analyzed, and the practical application of advanced technologies in building construction is discussed for reference.

No abstract