This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Journal of Physical Chemistry C, copyright c American Chemical Society after peer review. To access the final edited and published work see http://pubs.rsc.org/en/journals/journalissues/tc. Two-dimensional (2D) self-assembly of star-shaped 1,3,5-Tris(4-carboxyphenyl)benzene molecules is investigated. Scanning tunneling microscopy reveals that this molecule can form three hydrogen-bonded networks at the 1-phenyloctane/graphite interface. One of these structures is close-packed and the two other ones are porous structures, with hexagonal and rectangular cavities. The network with rectangular cavities appears to be the most stable structure.2