When most people think of chemistry, the traditional image of the white lab coat, gloves, and goggles hunched over an erlenmeyer flask, surrounded by a slew bottles marked “DANGER,” may come to mind. However, this visual is more fitting for a synthetic or organic chemist. The research I am doing is in the concentration of physical chemistry, and while I still work with chemicals and follow standard safety procedures, one aspect of the Wustholz lab differs from the stereotypical chemistry lab: we work with lasers.
At the beginning of the summer I developed a series of steps that I need to complete in order to have a successful summer researching auto paints. The first step was stabilizing the colloidal silver nanoparticles that my lab uses; we call them colloids for simplicity. Colloids are a suspension of silver nanoparticles in a sodium citrate and water solution. Stable colloids can be applied to auto paint samples, amongst other substances, for surface-enhanced Raman spectroscopy analysis. The trick is getting them to remain stabilized. Over the past semester, our colloids were only stable for a max of two days. The lifespan of colloids should be upwards of two weeks. After reviewing the procedure that we had been using all semester, we found some flaws. We discovered that our sodium citrate was expired by three years and that we were not boiling the silver nitrate enough before adding the sodium citrate. We corrected these two details and now we have colloids that last for three weeks! With stabilized colloids, I am able to move on to step two, reproducibility of auto paint standards.
So, I finally had my Photobase Generator, but lots of questions.
First, why did it seem to release acid upon irradiation? Upon reviewing the paper in which this molecule was synthesized, I discovered that they had published no actual pH data, only that the product had decomposed upon irradiation into two products, one of which was cyclohexylamine, the basic compound. Because cyclohexylamine was released, it had been classified as a photobase generating solution, which made sense. However, 6-nitrocoumarin was another product, and I couldn’t find any record of it’s acidic properties. My assumption was that perhaps the nitrocoumarin was actually more acidic than the cylclohexylamine was basic. Perhaps that would account for the drop of pH. However, quick tests proved that the nitrocoumarin was relatively basic, so that couldn’t be the solution.
I apologize for not posting as much as I probably should, but up to this point, despite a large number of trials and theories, very little overall progress has been made, due to a number of extenuating conditions. Let’s talk.
My name is Aaron Bayles, and I’m a sophomore at the College, currently studying abroad in Sevilla, Spain. Before I left for the semester, I was working in Dr. Harbron’s chemistry lab, investigating a particular set of fluorescent polymer nanoparticles that can both provide information about the acidity of a solution via the fluorescence of the molecules, as well as modify the pH through exposure to UV radiation. And I’ll be coming back to continue this research this summer!