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Template-directed polymerization is an effective approach used to afford regular 2D covalent organic frameworks (COFs), thus the regularity of the template is crucial for the quality of the resulting 2D COFs. For the Ullmann reactions on Cu(111), aryl iodides and bromides are activated at low temperature to form organometallic C–Cu–C structures, which lead to kinetic trapping and irregular organometallic networks. Therefore, the subsequent annealing step can only afford irregular 2D COFs. In this manuscript, the molecule 4,4′′-dibromo-5′-(4-chlorophenyl)-1,1′:3′,1′′-terphenyl incorporated two Br terminals and one Cl terminal has been used to demonstrate different reactivities of a C–Cl bond and a C–Br bond via the hierarchical activation of the C–Br bond and the C–Cl bond on Cu(111). At room temperature, zigzag, armchair, and ring-like organometallic chains formed due to the activation of the C–Br bond to generate a C–Cu–C structure while C–Cl remained intact, illustrating that the C–Cl bond is more stable than C–Br. Further annealing at 433 K activated the C–Cl bond to produce regular organometallic networks as the thermodynamic product. Using the simpler molecule 1,3,5-tris(4-chlorophenyl)benzene as the precursor, the self-assembly of the intact molecules was observed on Cu(111) at 300 K without activation of the C–Cl bond. After annealing at 433 K, similar thermodynamically stable organometallic networks formed directly, which were used as a template to generate regular 2D COFs upon further annealing at 510 K. [ABSTRACT FROM AUTHOR]

Diverse self-assembled structures were obtained on Cu(111) and Ag(111) surfaces by using a simple and small 4,4′′-dichloro-1,1′:4′,1′′-terphenyl molecule. Surprisingly, a complicated supramolecular self-assembled vortex structure, composed of 15 molecules in a large unit, was realized through the collaboration of hydrogen bonding and halogen bonding. [ABSTRACT FROM AUTHOR]

The efficiency of Ullmann reaction of aryl chlorides on an Au(111) surface has been substantially increased by using dosed Cu as a catalyst. The different reactivity of aryl bromides and aryl chlorides has been exploited to design a programmed, on-surface synthesis to form 2D covalent organic frameworks. [ABSTRACT FROM AUTHOR]

The reaction of aryl chloride and porphyrin macrocycles, which are merged into a single precursor, has been achieved on Cu(111). Scanning tunneling microscopy analysis of the oligomer products showed that the adjacent porphyrin moieties linked mainly by the phenyl group with the porphyrin macrocycle.