Carbon allotropes comprising sp-hybridized carbon atoms have been investigated for decades for their molecular structure. One of the unsolved mysteries is whether they should take a linear or cyclic configuration in condensed phases due to the lack of atomistic characterizations. Herein, we designed a molecule with a C6 skeleton as a model system to address this issue, which was achieved by eliminating Br atoms from hexabromobenzene (C6Br6) molecule on the Ag(111) substrate via thermal treatment. It is found that the C6 ring intermediate resulting from complete debromination is energetically unstable at room temperature based on theoretical calculations. It subsequently transforms into the C6 polyynic chain via a ring-opening process and ultimately polymerizes into the organometallic polyyne, whose triyne structural unit is revealed by bond-resolved noncontact atomic force microscopy. Theoretical calculations demonstrated an energetically favorable pathway in which the ring-opening process occurs after complete debromination of C6Br6. Our study provides a platform for the synthesis of elusive carbon-rich materials.

This study focuses on investigating interfacial interactions and the adhesion mechanism of polymer‐metal interfaces in nano‐molding. Polyphenylene sulfide (PPS), polyamide 6 (PA6), and isotactic polypropylene (iPP) were chosen as candidate polymers, and aluminum (Al), and copper (Cu) were used as metal substrates. By establishing the metal matrix composed of a rectangular pit with length, width, and depth of 4.5, 4.5, and 2.0 nm, respectively, six paired polymer‐metal interfacial systems in a cuboid of 7.5 × 7.5 × 11.5 nm, consisting of metal, polymer, and vacuum layer (from bottom to top) were constructed. Molecular dynamics simulations were performed to calculate interfacial interactions and bonding processes. Results showed that wall‐slip behavior was pronounced in nano‐molding. Viscoelasticity and polarity of the polymers played a crucial role in interfacial interactions, which guided the wall‐slip behavior and greatly affected the bolt performance. PA6 and PPS were more suitable for molding than iPP on both Al and Cu substrates. PA6 showed the best filling and bonding performances, followed by PPS, while iPP revealed the poorest performances. The Cu substrate exhibited better anchor strength and filling rate than Al substrates with the same polymer.

Carbon, as an indispensable chemical element on Earth, has diverse covalent bonding ability, which enables construction of extensive pivotal carbon-based structures in multiple scientific fields. The extraordinary physicochemical properties presented by pioneering synthetic carbon allotropes, typically including fullerenes, carbon nanotubes, and graphene, have stimulated broad interest in fabrication of carbon-based nanostructures and nanomaterials. Accurate regulation of topology, size, and shape, as well as controllably embedding target spn-hybridized carbons in molecular skeletons, is significant for tailoring their structures and consequent properties and requires atomic precision in their preparation. Scanning probe microscopy (SPM), combined with on-surface synthesis strategy, has demonstrated its capabilities in fabrication of various carbon-based nanostructures and nanomaterials with atomic precision, which has long been elusive for conventional solution-phase synthesis due to realistic obstacles in solubility, isolation, purification, etc. More intriguingly, atom manipulation via an SPM tip allows unique access to local production of highly reactive carbon-based nanostructures. In addition, SPM provides topographic information of carbon-based nanostructures as well as their characteristic electronic structures with unprecedented submolecular resolution in real space. In this review, we overview recent exciting progress in the delicate application of SPM in probing low-dimensional carbon-based nanostructures and nanomaterials, which will open an avenue for the exploration and development of elusive and undiscovered carbon-based nanomaterials.

Metal–organic nanostructures are attractive in a variety of scientific fields, such as biomedicine, energy harvesting, and catalysis. Alkali-based metal–organic nanostructures have been extensively fabricated on surfaces based on pure alkali metals and alkali metal salts. However, their differences in the construction of alkali-based metal–organic nanostructures have been less discussed, and the influence on structural diversity remains elusive. In this work, from the interplay of scanning tunneling microscopy imaging and density functional theory calculations, we constructed Na-based metal–organic nanostructures by applying Na and NaCl as sources of alkali metals and visualized the structural transformations in real space. Moreover, a reverse structural transformation was achieved by dosing iodine into the Na-based metal–organic nanostructures, revealing the connections and differences between NaCl and Na in the structural evolutions, which provided fundamental insights into the evolution of electrostatic ionic interactions and the precise fabrication of alkali-based metal–organic nanostructures.

Metallo-porphyrins with different metal centers display unique properties and are essential in various biological and chemical processes. Enormous efforts have been devoted to enriching the family of metallo-porphyrins on surfaces mainly through metalation processes within porphyrins and exogenous pure metals or intrinsic surface adatoms, which have focused on transition elements. However, less attention has been paid to the synthesis of alkali-metal-based porphyrins on a surface. Herein, by a combination of scanning tunneling microscopy (STM) imaging/manipulations and density functional theory (DFT) calculations, we report the fabrication of Na-porphyrins on Au(111) by introducing NaCl, i.e., two double-layered Na-centered porphyrins. Moreover, the interconversion between them was realized by precise STM manipulations. Our results demonstrate the feasibility of metalation by applying inorganic salt, which would serve as a promising strategy to embed intramolecular metal components into porphyrins for further functionalization and modification.