Tang Zhexiong, Hicks Raea K, Magyar Rudolph J, Tretiak Sergei, Gao Yuan, Wang Hsing-Lin
PCAS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Langmuir. 2006 Oct 10;22(21):8813-20. doi: 10.1021/la060914k.
We report the synthesis of a series of amphiphilic molecular building blocks that can be self-assembled at the air-water interface to form two- and three-dimensional nanostructures with tunable optoelectronic properties. Compression of these molecular building blocks using the Langmuir-Blodgett method gives rise to monolayer and multilayer thin films with different packing densities and electronic properties that are tunable due to varying pi-pi (hydrophobic) interactions. Depending on the noncovalent interaction between chromophores, we observe a transition toward denser packing with increasing number of phenylene ethynylene repeat units. Additionally, we use quantum-chemical simulations to help determine the excited-state electronic structure, intermolecular interactions, and packing trends. Our results demonstrate that the interplay between dipole-dipole and pi-pi interactions dominates the formation of thin films with various packing densities and determines the associated optical properties.
