This summer, I had three or four big projects. The most stressful was certainly packing and moving (and unpacking) all the labs to the new building. I spent at least three weeks on that, full time, starting during spring final exams. I had a summer undergraduate researcher to mentor and supervise for ten weeks, in addition to coordinating both of the research programs as I usually do. I attended a conference and wrote a book chapter. It was not a relaxing break. I worked a lot, and feel productive, but the things I did were not always the things I wanted to prioritize.
For the first time since we hired the two newest faculty in my department (2012), I had the summer undergraduate research grant. My student, B, was pretty awesome. He just finished his first year at college, was recognized as a bright, motivated student which definitely came through during the application process. Although I only had three applicants this time, and that was disappointing, B was the only one who seemed genuinely interested in the project. Nevertheless, he is not planning to major in chemistry and is considering medical school. His academic advisor told me B was thinking of transferring to another college because he was feeling under-challenged here; hopefully the research experience helped him decide to stay.
Our project was to synthesize an ionic liquid crystal in the series I have previously worked with, this time containing samarium instead of a first-row transition metal. I vaguely thought the samarium might make the compound fluorescent, but that wasn't the main idea. I wanted something not too complicated (related to what I'd already done) but still new, and we had to have simple analyses both because of the scheduled move to the new building and B's relative inexperience. We planned to do melting points, maybe some polarized light microscopy at different temperatures if the heated microscope stage I had commissioned arrived and worked, atomic absorption spectroscopy to determine the samarium content, gravimetric analysis of chloride, and combustion analysis for carbon and hydrogen. B spent the first two or three weeks reading the literature and compiling an annotated bibliography, then we did attempt synthesis. The product was a boring white color, but very soapy or fatty in texture. It seemed to melt at room temperature so we struggled to get the methanol solvent out of it. We couldn't use vacuum filtration because the solid would not stay on the filter. Finally, I suggested "freezing" it in the refrigerator then pouring off the liquid methanol that formed a layer on top of the solid. B repeated this several times until he had a constant mass and then we pronounced it done, although it probably had methanol and possibly unreacted ligand mixed in.
The next step was to work on the elemental composition. B started with the gravimetric analysis, because the procedure was exactly the same as in his spring chemistry lab: react the dissolved chloride ions with silver nitrate and filter off the solid silver chloride product which is then weighed. We used the new house vacuum system, which is brilliant, but one of the three filtering crucibles took more than a week to complete the filtration. The results of the three trials had poor precision, so we started another set of three trials with a different set of filtering crucibles. The first two of these are still in progress after two weeks, so it seems unlikely that they'll be any better. I can't tell if I chose three "bad" crucibles from the supply (the movers mixed up our carefully segregated "good" and "bad" supplies), or if the sticky, fatty nature of the compound is gunking them up. Additionally, B added about four times as much water as he should have when making these solutions, so the volume of solution that needs to be filtered is almost ridiculous.
Originally, we had planned to use atomic absorption to determine the samarium, but the AA is still not operational because there is no exhaust system installed. This was noted on May 1 during a walk through with the lab designer, just before we took possession, and has still not been fixed. So, B and I fell back on complexometric titration using EDTA. I found a sketchy paper in an Indian journal from the 1980's and we used that as the base for our analysis. B had also done this type of titration in the spring, and it seemed to work but the results were a much lower percentage of samarium than expected. Could be the method, could be the analyst, and could also be the truth.
The combustion analysis haunted me all summer. I've never done one and while in theory it's simple, 19th century chemistry, actually performing it turned out to be difficult. First we had to figure out the apparatus. I had the U-tubes and borrowed a big glass tube for the reaction chamber. We connected the parts with short pieces of Tygon tubing. I spent about a week trying to figure out how to connect the compressed oxygen cylinder to the big tube, and finally gave up. Instead, we used the decomposition of potassium chlorate (with manganese dioxide catalyst) from an old general chemistry experiment to produce oxygen gas in situ. I had B scale this up slowly to be sure it wouldn't explode or anything before we added any of our product. At last, we did three trials with the compound and they were pretty spectacular to watch. About a minute of heating, during which nothing seemed to happen but oxygen bubbles were produced, then about ten seconds of intense fire as the compound burned, then it's over. Again, results were very low for both carbon and hydrogen. I think it's because the absorbents were solids and the combustion gases passed through them too quickly. As a back up, I sent a sample to a contract lab for instrumental combustion analysis, and those results were closer to our calculated amounts, though still low.
So I'm not sure if anything B did this summer is reportable. He's working on the poster and the final report now, and we'll present at the usual venues this coming year. I hope to attend CERM with him in May, but I can't point to a single experiment we did that was successful. I'm embarrassed by this and I feel guilty, as if I should have done more myself or maybe I should have taught B better. I don't want to present a "science fair" poster (as I've heard certain professional chemistry disparage some of the work that is presented at conferences) and be ridiculed. Also, B is only a sophomore now, and he has a 19-year-old's critical thinking skills, but he does have more than the usual level of self-confidence. This combination seems to make him say inappropriate things about his work. I keep telling myself that this is how he will learn, and he can't be much different from students I've worked with in the past who all turned out okay.
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