Date of Award
Ph.D. in Chemistry
Chemistry and Biochemistry
The size, shape and structure of the materials determines its properties in any scale. When the size of the material reaches nanometer scale, it shows a strikingly different property from the bulk. Monodisperse metal nanoparticles are highly desired due to its unique properties which can be explored for targeted applications. The nanoparticles with size less than 3 nm, atomically precise metal nanoparticles can be achieved, whereas nanoparticles in 3-100 nm range are monodisperse in size but not atomically monodisperse. Thiolate protected gold nanoparticles size less than 3 nm forms highly stable atomically precise compounds with distinct number of gold atoms and thiolate ligands, represented by Aun(SR)m, which are referred as gold nanomolecules (Au NMs). Au NMs have unique physical and chemical properties which are dependent on “n” and “m”. The overall composition and resulting properties of Au NMs are dictated by the type of capping ligand. Currently based on the type of capping ligand, Au NMs are classified into three main categories, aliphatic, aromatic, and bulky thiolate Au NMs. These distinct categories form unique series of Au NMs represented as aliphatic, aromatic, and bulky Au NMs series. However, recent discoveries on various aromatic thiol protected Au NMs reveals that these Au NMs deviate from aromatic series when size become large. Meanwhile, core size conversion brought a unique synthesis route of inter-converting between these three series with comparable sizes. This dissertation focuses on studying the ligand effects on Au NM using core size conversion on new Au NMs with previously studied thiols and previously studied Au NMs with new thiols, and by closely comparing the structures with same structural arrangements.
Chapter 2 of this dissertation focuses on the first core size conversion of plasmonic Au NMs and its reaction pathway using MALDI-MS, ESI-MS, and UV-visible spectroscopy.
Chapter 3 of this dissertation details the process in which digestive ripening synthesis method yields atomically precise Au NMs. In this work, the unique series achieved using Brust synthesis method is also achieved through digestive ripening method which was confirmed using MALDI-MS, ESI-MS, and UV-visible spectroscopy.
Chapter 4 of this dissertation introduces the crystallographic structure determination of p-methyl benzene thiolated Au36(PMBT)24 nanomolecule and details the ligand effects on Au36(SR)24 structure using all four reported crystal structures.
In Chapter 5, we took a turn and explored a different metal, Palladium. In this chapter, the dissertation focuses on discovery and synthetic protocol development of atomically precise palladium nanoclusters using phenyl ethane thiol.
Chapter 6 of this dissertation explains the vital nature of size exclusion chromatography (SEC) in our works and focuses on the effect of column length in SEC using tert-Butyl thiol protected Au NMs.
Chapter 7 of this dissertation details original research proposal and investigation into the ligand effect by employing core size conversion of Au144(SR)60 with three aromatic thiols, where the para position is substituted with methyl, ethyl, and iso-propyl groups respectively.
Eswaramoorthy, Senthilkumar, "Core Size Conversion and Ligand Effects on Gold Nanomolecules Structure and Properties." (2022). Electronic Theses and Dissertations. 2213.
Available for download on Thursday, August 15, 2024