The growth of supramolecular assembly on a surface is governed by the competition between intermolecular interactions and molecule-substrate interactions. Here, we investigated the formation of molecular networks on the passivated Si(111)-B semiconductor surface with scanning tunneling microscopy at low and room temperatures. For that purpose, we synthesized molecular species with a similar backbone but specific end-groups that allow to vary the balance between intermolecular interactions and molecule-substrate interactions. We find that the molecules self-assemble into molecular networks with different arrangements. When the terminal hydrogen atoms are substituted by halogen atoms, the compact network turns into an open framework, showing the strong contribution of the halogen atoms into the intermolecular interactions