title: Synthesis and characterization of amphiphilic phenylene ethynylene oligomers and their Langmuir-Blodgett films.
abstract: 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.
authors.affiliation: PCAS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Zhexiong
authors.initials: Z
authors.lastname: Tang
authors.forename: Raea K
authors.initials: RK
authors.lastname: Hicks
authors.forename: Rudolph J
authors.initials: RJ
authors.lastname: Magyar
authors.forename: Sergei
authors.initials: S
authors.lastname: Tretiak
authors.forename: Yuan
authors.initials: Y
authors.lastname: Gao
authors.forename: Hsing-Lin
authors.initials: HL
authors.lastname: Wang