Headshot of Robin Eluvathingal
Author: Robin Eluvathingal | Major: Biochemistry | Semester: Fall 2024
My name is Robin Eluvathingal, a biochemistry major in the Chemistry & Biochemistry department; over the past Fall semester of 2024 I have been working in Dr. He’s Organic chemistry lab. The overall goal of the lab is to develop new materials that have interesting physical, electronic, optical, and adaptive properties. My project’s focus is to create a new compound containing long carbon chains, which can then be used to add those chains to carbon nanotubes (CNTs); we hope to improve their dispersibility & solubility, as this would greatly improve CNT utility & manufacturing processes.
My previous Spring 2024 semester ended with me successfully synthesizing and isolating the iodonium salt with 12-carbon (dodecyl) chains as a substituent, but still needing to synthesize and isolate the 8 (octadecyl) and 16-carbon (hexadecyl) chain salts. The reason I needed the varying lengths is to be able to determine if varying chain lengths have an effect on the dispersibility, solubility, or other properties of the CNTs that might be interesting to know.
During the summer, I worked on obtaining these salts and characterizing them. Using the same synthesis method as the 12-carbon chain iodonium salt, I successfully synthesized and isolated the 8 and 16-carbon chain salts. I was able to take NMR (nuclear magnetic resonance) spectrums for the isolated compounds, but the spectra showed some impurities. Due to the varying chain lengths, the salts themselves had different solubilities. While the 12-carbon iodonium salt was able to be isolated with a second column in ethyl acetate, dichloromethane, and methanol, the other salts required more testing. The hexadecyl salt showed some success at first using the same column system as the dodecyl iodonium salt, but rechecking with NMR showed meta-Chloroperoxybenzoic acid remained (mCPBA). I then tested the solubility of the compound I had and mCPBA against a variety of solvents, finally narrowing it down to diethyl ether and ethyl acetate. Precipitation of the salt in diethyl ether finally yielded pure product and I was able to obtain an NMR spectra of publication quality.
In between all of these, I was using the isolated dodecyloxy iodonium salt compound to test the functionalization procedure for the CNTs. The procedure was based on an earlier paper from Dr. He in which she proposed the use of iodonium salts as a way to functionalize carbon nanotubes. With the help of Dr. Gupta, the postdoc, who assisted in utilizing the sodium metal for the sodium naphthalide reducing solution, I used my newly synthesized salt, sodium naphthalide, and carbon nanotubes to perform the functionalization procedure in the minimal oxygen environment of the glovebox. This was a very cool, though somewhat nervewracking, experience, as it made me feel like I had metaphorically graduated from the undergraduate organic chemistry labs to the more serious “research labs”.
After some preliminary tests I left the lab for the remainder of the summer, and when I returned for the fall semester, continued where I left off. I continued to refine the CNT functionalization process and tested the other salts, including the 8 and 16 carbon chain salts; I isolated the octadecyloxy iodonium salt, which, due to its shorter alkyl chains, was not solid like the other salts, but rather a thick, viscous, golden liquid.
Functionalization of the carbon nanotubes was successful; I was able to characterize the addition of all 3 salts to the CNTs, but wanted to see if the percentage of the CNTs that were functionalized could be improved (this could yield better dispersibility). Though my project is not finished with the cessation of the Honors College Research grant, I hope to finish early in the spring semester. In addition to increasing the percentage functionalized, I would like to test the dispersibility in many more common organic solvents in order to provide practical applications of my discoveries. I am already registered to present my research at the ACS conference in San Diego in March of 2025, and am excited to publish my results in an academic journal soon!