Monolayers of 2-(3,4,5-(trisdodecyloxyl)phenyl)[1,3,4]oxadiazole based "tripod" dye, P2G, has been studied at the air/water interface with in situ X-ray reflectivity. Compression of the disordered Langmuir-Blodgett monolayer film induces a transition to a unique ordered phase, representing a supramolecular assembly with a unique spatial distribution and orientation of the molecules. At low pressure, the molecules having face-on orientation are interdigitated by the three arms. After first transition in the pi-A isotherm, the molecular conformation is turned into an edge-on orientation, where the molecules are self-assembled into supramolecular structures.