We reported here design syntheses of a series of amphiphilic molecular building blocks that can self-assembled at the air-water interface to form 2D and 3D nanostructures with tunable opto-electronic properties. Compression of these molecular building blocks with tunable π-π (hydrophobic) interactions using Langmuir-Blodgett method gives rise to monolayer thin films with different packing density and electronic coupling between chromophores. Depends on the noncovalent interaction between chromophores, we observe a transition of packing density with increasing sized of phenylene acetylene repeat unit. Furthermore, we use a series of spectroscopy tools such as neutron scattering to probe the nanoassembly structures at the molecular level. We also use simulation method to help determine the excited state electronic structure. Our results demonstrate that the interplay between dipole-dipole and π-π interactions dominate the formation of thin films with various packing density and their associated optical properties.