Synthesis of spherical and octahedral gold nanoparticle superlattices driven by aldol condensation reaction

Abstract

Nanoparticles superlattices are of a great current interest due to the wide range of applications, which arise due to the emergent and collective properties such as catalysis, drug delivery, and biomaterials. While, spherical nanoparticles assemble into lattice symmetries, which are determined by simple packing criteria and has been well studied, the assembly of anisotropic nanoparticles has also generated tremendous interest. This interest stems from their unique optical and chemical properties, which are related to their shape and size. Additionally, the directional properties of anisotropic nanoparticles in self-assembly process, coupled with covalent bonding might also lead to the emergence of new features and properties. In this thesis paper, we have studied the synthesis of spherical and octahedral gold nanoparticles superlattices driven by aldol condensation reaction, a kind of covalent bond. The gold nanoparticles superlattices synthesized by covalent bond are expected to be stable under a wide range of conditions, such as different solvents and temperatures, unlike the superlattices obtained by the DNA-mediated method or the slow solvent evaporation method. Spherical gold nanoparticles superlattices help to understand the aldol condensation reaction used in synthesis. Furthermore we also try to understand the self-assembly of anisotropic nanoparticles through the octahedral nanoparticles superlattices. The structure of spherical and octahedral gold nanoparticles superlattices are analyzed using scattering techniques such as the Small-angle X-rays. In addition, highly stability of superlattices under various solvents(DMF, Ethanol, Water, Toluene) and high temperature (170 $^\circ C$) conditions were also confirmed. Therefore, it is expected to open new possibilities that can be applied to sensing field as stable photonic crystals