Author: Robin Eluvathingal | Major: Biochemistry | Semester: Spring 2024

My name is Robin Eluvathingal, a biochemistry major in the Chemistry & Biochemistry department; over the past spring semester of 2024 I have been working in Dr. He’s Organic chemistry lab.  I originally joined Dr. He’s chemistry lab after an assignment in Dr. Coridan’s chemistry class where I reviewed and presented University of Arkansas chemistry faculty research.  My presentation covered Dr. He’s paper that used a novel method of functionalizing carbon nanotubes using iodonium salts.  I had already known about nanomaterials and their promise as the material of the future, so Dr. He’s paper on functionalize carbon nanotubes to modify their behavior was especially interesting to me.

Carbon nanomaterials such as graphene and carbon nanotubes have been the subject of great research interest due to their unique electrical and physical properties.  However, they tend to aggregate and have poor solubility in common organic solvents due to their pi-pi interactions.  One way this could be overcome is by adding long alkyl chains to these compounds in order to add attractive-dispersion forces and improve their solubility, though this has only been done in liquid crystal design.  My project seeks to translate this idea to carbon nanotubes by synthesizing a novel iodonium salt and then functionalize carbon nanotubes with this salt before characterizing the behavior of both the salt and the carbon nanotubes.

Since this salt has never been formed before, this past semester was one of much difficulty and repetition. The original synthesis scheme had multiple steps, with the yield for later steps being unknown; most likely outcome would be a low overall yield and long synthesis time.  Dr. He instead recommended reading a new paper that showed a potential one pot method of synthesizing the iodonium salt.  The drawback however, was that the paper showed the synthesis of much shorter alkyl chains and without alkoxides; how this would affect the synthesis was unknown.  I tried the procedure with 1-bromododecane and pyrogallol, once, twice, thrice, and still no product.  I tried adding iodine and doing an asymmetric synthesis, still no luck.  I switched to catechol, thinking maybe the number of hydroxyl groups was affecting it, still no luck.  After months of experiments I still had nothing to show for it.  Finally, I tried phenol, with only one hydroxyl group.  It seemed the product had formed!  I confirmed by taking an crude NMR of the reaction mixture, and product was present.  I then carefully did a column, isolating what I believed was the compound, before taking an NMR to see: it was not.

At first, this made no sense.  The product was present in the original reaction mixture, but after filtering through the column it wasn’t there?  After discussing the issue with Dr. He and Ravindra, a postdoctoral researcher in the lab, I realized this issue.  The compound had long alkyl chains, so I thought it would exhibit more polar behavior.  However, I had failed to account for the fact that though this was a “greasy” compound, it was still a salt, and thus, was much polar than the original starting material with the alkoxy side chains.  After redoing the experiment and isolating the proper compound, I took an NMR, it was the product!  I later confirmed by MALDI (Matrix Assisted Laser Desorption) and was overjoyed to finally obtain the compound after months of work.

Now that I have successfully created the salt with a 12-carbon side chain, I still need to synthesize 8 and 16 carbon side chain salts as well in order to observe how varying side chains affect the salts properties as well as functionalizing the carbon nanotubes themselves.  I plan to continue this project through the next semester as part of my honors thesis and hopefully publish my work.  The past semester has been one of much difficulty, but it has solidified my interest in conducting research as part of my career.  The process of coming up with an new idea, devising and testing an experiment to collect my data, and contributing new knowledge to the scientific body is immensely rewarding.