Honors Capstone Project
Date of Submission
Dr. Michael B. Sponsler
Dr. Mathew Maye
Arts and Science
Capstone Prize Winner
Won Capstone Funding
Sciences and Engineering
Chemistry | Organic Chemistry | Other Chemistry
There have been great advances in electronics and technology within the last few years. The field of nanotechnology can further improve electronics in terms of efficiency, size and costs. There exist nanowires and nanotransistors that could accomplish this, however there exists no good method of connecting the two components together. Using the bottom-up approach and chemical synthesis, the goal is to synthesize molecular jumper cables and connectable molecular components (CMCs).
The template of the CMC will have two ruthenium (Ru) metal centers connected by a conjugated, organic bridge. Coordinated to the ruthenium metal centers will be different ligands that affect the properties of the complex. Many methods of synthesis exist to allow design of the given template. The reactions and methods studied were olefin metathesis for metal incorporation (OMMI) using Grubbs catalysts, metal hydride reactions, and organic reactions such as radical and substitution reactions. The ligands studied were aurophilic and pincer ligands. These ligands contain outward-directed lone pairs that will aid in single molecule conductivity studies. The ligands were methylthio-1,4-diphenyl-1H-1,2,4-triazolylidene, bipyridine, pyrazine, 2,6-bis(chloromethyl)pyrazine, 2,6-bis(diphenylphosphinomethyl)pyrazine, and 2,6-bis((diphenylphosphino)methyl)pyridine.
Complexes were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), ultraviolet-visible spectroscopy (UV-Vis), infrared spectroscopy (IR), cyclic voltammetry (CV), atomic force microscopy (AFM), and ab-initio calculations using Gaussian 03W were also conducted. If successful, the last study to be conducted is single molecule conductivity studies in collaboration with a research group from Arizona State University. 1H NMR was used to monitor reaction progress and along with IR spectroscopy, we were able to identify the complexes synthesized. UV-Vis spectroscopy provided information on the electronic structure of the complexes while CV provided information on redox stability and redox potentials. AFM provided information on topography and Gaussian allowed us to compare effects of different ligands, such as stability, upon coordination to the complexes.
The complexes synthesized using Grubbs catalysts and OMMI were unsuccessfully isolated. The greatest obstacle was stability, with many of the complexes decomposing over time. The complexes of the metal hydride insertion reactions were plagued with solubility and purification problems. However, a diruthenium complex was discovered to show potential as a CMC. In addition to the above obstacles, another problem was synthesis of the desired ligands that restricted the range and progress of the project. However, the project has yet to exhaust all the options and there are many other approaches and methods that will be investigated.
Ling, George, "SYNTHESIS OF DIRUTHENIUM COMPLEXES AS CONNECTABLE MOLECULAR COMPONENTS" (2009). Honors Capstone Projects - All. 454.
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