The self-assemblies of half-halogenated ͑ZnPcCl 8 and ZnPcF 8 ͒ and nonhalogenated zinc phthalocyanine ͑ZnPc͒ molecules on an Ag͑111͒ surface are studied by means of a combined experimental and theoretical study. The experiments involve scanning tunneling microscopy ͑STM͒ and the theoretical study is based on the topology of electron density obtained from density-functional ͑DFT͒ calculations. STM experiments reveal different structures due to the presence or not of halogen atoms at the periphery of the molecule, but the main differences are observed comparing ZnPcCl 8 and ZnPcF 8 deposits. In the case of ZnPcCl 8 , some faults are found periodically at the end of a ripening process that are not observed in the case of ZnPcF 8 . DFT calculations on the corresponding 2D molecular networks show differences in the nature of the H¯F and H¯Cl hydrogen bonds but also differences in the equilibrium molecular lattice parameter. We demonstrate that the intermolecular interaction can be tuned by chemical substitution and that the substrate-imposed stress can have a significant influence on the molecular self-assembly.

The adsorption and ordering of zinc phthalocyanine (ZnPc) and octachloro zinc phthalocyanine (ZnPcCl(8)) on an Ag(111) surface is studied in situ by scanning tunneling microscopy under ultrahigh vacuum. Two-dimensional self-assembled supramolecular domains are observed for these two molecules. We show how substituting chlorine atoms for half of the peripheral hydrogen atoms on ZnPc influences the self-assembly mechanisms. While intermolecular interactions are dominated by van der Waals forces in ZnPc molecular networks, ZnPcCl(8) molecular packing undergoes a sequential phase evolution driven by the creation of C-Cl...H-C hydrogen bonds between adjacent molecules. At the end of this evolution, the final molecular assembly involves all possible hydrogen bonds. Our study also reveals the influence of molecule-substrate interactions through the presence of fault lines generating a stripe structure in the molecular film.

On-surface synthesis of tetracyanobenzene molecules with Mn atoms is presented. From metal-organic coordination networks at room temperature, Mn-phthalocyanines and finally small domains of polymeric Mn-phthalocyanines are formed upon annealing on the Ag(111) surface. Step-by-step on-surface reaction is studied in situ by scanning tunnelling microscopy under ultra-high vacuum.