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Welcome!
This site is dedicated to my research. My name is Patrick Gasda, and I'm a senior at Ursinus College. Below you will see the most up-to-date poster and powerpoint presentations that I use (beware! they're big ppt files). They explain all the work that I've done so far. There is some more detailed information if you follow the links to the left. The following news posts are a weekly (for the most part) updates about what research I've done. Included in them are the raw data that I have collected as well as some interpretation of my results. Scroll down to the bottom to see what's been happening as early as the beginning of the summer. If you have any questions, email me here (no spam, thanks!)
News | 10/20/06 | It’s been awhile… …But its okay since not much work has been done on the research front. Once classes got really underway in September, I haven’t had time to think about my longer-term projects. I think that once my graduate school applications are sent out, I can reorganize my schedule to give myself enough time to do stuff in the lab. In case you are wondering, I’m looking at the following schools (in no particular order): University of Maryland College Park, University of North Carolina Chapel Hill, University of California Berkeley, Cornell University, and Northwestern University. They all have some things in common: large schools, plenty of resources, and strong chemistry departments. I’m very interested in studying material science, physical chemistry, and solid-state chemistry, among other things. Hopefully, all five have at least one lab with some mix of my interests that is willing to pick me up. The thing is, I’ve been working and worrying about all this stuff for about two months now, and it’s really driving me insane. I’m aiming to have my recommendation stuff squared away (it’ll be in my professor’s hands then) by the end of the week. But enough about that for a moment, if all goes according to plan, the following goals will be reached by the end of November. I will finish the reaction so that DNA is bonded through the cross-linker to nanotubes. This step will be characterized using fluoremetry (the DNA has a fluorescing group). Also, I want to try a different approach to functionalize the nanotubes. We will order some p‑aminoanaline to skip the whole nitro group reduction altogether. Maybe it will work by itself or maybe I will protect one of the amino groups before the reaction. I’ll inform you of any developments as they occur. | | 7/24/06 | I've been forgetful I know, it has been a month since I really updated this site. I would be surprised if anyone actually reads this thing anymore. Well, the month of July has been particularly slow. We have mostly been waiting for supplies to come in for our experiments with quantum dots (nanoparticles) and DNA. After that, we spent about two weeks fiddling with a reaction where we coat cadmium selenide particles with zinc sulfide. The DNA we ordered has a sulfur group attached to it, so are hope is that it will form an ionic bond with the zinc. Unfortunately, our DNA order only came in a few days ago and there's almost no point in starting that reaction right now. There's only one week left and I have to prepare my poster, paper, and presentation for Friday. Wish me luck! | | 6/28/06 | Summer Fellows Week 6 Summer Fellows is about halfway done and so far I think I’ve been fairly successful with my work. Yesterday I did a reaction that attached the cross-linker to the nanotubes. If that was done right then the next step would be to attach the DNA. For the reaction we did yesterday, I used the nanotubes that we electrochemically reduced (electricity was ran through our product from step two). I’m still interested in finding a way to reduce them chemically, or even covalently bonding 1,4-benzenediamine to the nanotubes and skipping the reducing step altogether. The thing is, the electrochemical reduction has been done before [PDF], and the point of this study was to figure out chemical pathways to the DNA functionalization that were less solvent intensive or had a higher yield. In that respect, we have not been as successful. So this is something I want to work on as we wait for the DNA to come in. In other news, I finally configured the IR spectrometers in the other room to work on the network. So now I can upload some spectra to show everyone what I’ve completed so far. Here’s the spectrum of the second step product [PDF]. Note that it is zoomed in to the relevant part of the spectrum. The peaks that I marked in red and the ones that we believe are from the NO2 bond stretches. They are where Dyke et al. predicted them to be. If you compare them to the spectrum of our starting material (4-nitroaniline) [PDF], you’ll see the same peaks (marked in red). The peaks marked in green are due to benzene and NH2 stretches. Over the past week or two, we’ve attempted to chemically reduce the NO2 group on our step 2 product to a NH2 group. These spectra show what we made so far. All four of these compounds were made using the same batch of our second step product which was reacted using slightly different reagents and reaction conditions. The top left spectrum is the most promising because we think we put carboxylic acid groups onto the nanotubes. We’re not quite sure how that happened and although it is worth looking into it, it was not the product that we expected to find. With the other three, either the reaction was not successful, or we just don’t know what to look for in the spectrum. We know that aniline has a strong doublet around 3500 cm-1, but as you can see, they are not present. It might be because the nanotubes are so large that they drown out the peaks that we are looking for. The fact that the spectra have a sloping baseline is indicative of the nanotube’s presence (nanotubes basically absorb at all frequencies). For now, we are assuming that the reactions did not work and we are looking into a different way to achieve that product. More on that next week. | | 6/15/06 | Computer Problems My computer suffered from a spy ware attack over the weekend and was out of commission for a while. While it was getting fixed I analyzed the data from the second attempt of the NO2 reduction reaction. The spectra indicated that the nanotubes now have carboxylic acid groups on them, which is not the product we expected. We think that the HCl reacted with the water in the system to oxidize the nanotubes walls rather than reduce the NO2 group. So we thought up a new reaction that would minimize water in the system. Yesterday we ran the reaction of acetic acid (vinegar’s main ingredient), tin, and nanotubes in DMF (our solvent). Since acetic acid is a weak acid, it should react slowly, so we added it all at once instead of slowly like we did with the HCl. We also did the reaction in a dry nitrogen atmosphere just to be safe. Today I’m going to analyze the data to confirm that the reaction happened as we planned. | | 6/09/06 | Step 3: NO2 Reduction Today I am reacting my product from step 2 with HCl and mossy tin to reduce the nitrobenzene functional group to aniline (refer to this PDF). This is the second time I am trying the reaction. I tried it on Friday, and after taking an IR, decided that it did not work. The spectrum is missing the characteristic NH2 peaks 3500 cm-1 and 3400 cm-1. Still present are the NO2 peaks at 1352 cm-1, 1337 cm-1, and 1326 cm-1 (the IR spectrum of our product from step two had peaks at 1350 cm-1, 1338 cm-1, 1327 cm-1). There are some strange peaks around 1985 cm-1 and 2075 cm-1, but I have not quite figured out what they are yet. We also haven’t quite figured out how to move files from the instrument, so it might be a while before I can upload spectra on this page. Until then, you will just have to look at the numbers. We are hoping that the mistake we made last time was in the post-reaction workup. Since I am adapting the reaction procedure from an older textbook to suit our needs, I am not sure how some of the steps would alter our product. Instead of neutralizing the leftover acid like last time, we are just going to filter the nanotubes immediately and wash them with water until the filtrate is neutralized. When we added base last week, a white precipitate formed which was probably from a side reaction of HCl and our solvent, DMF. It could have also been a tin chloride salt that is supposed to form (according to the original procedure). Dr. Ellison hypothesized that adding base makes a tin hydroxide (which is why it redissolved in acid), and is probably something that we don’t want to happen. Whatever it was, it was not the product we wished to form and we believe that adding the base (since it was very strong) was a mistake. Also, skipping the neutralization step will make product isolation and characterization easier. | | 6/01/06 | Fisher Fiasco Large chemical suppliers like Fisher Scientific or Sigma-Aldrich are real handy to researchers since they can send thousands of types of chemicals right to your lab for cheap. Thing is, when things go wrong, you get screwed. Here’s the story: last week we ordered 100mg of mossy tin for our experiment to reduce the NO2 group on our product to NH2 (see step 3 [PDF]). It’s this sort of critical reagent (that we can’t make on our own) that requires us to use Fisher as a supplier. According to their website, mossy tin is in stock (unfortunately, you have to be logged in to see their stock). For $45.20, we bought 100 grams of 99.8% pure mossy tin. After waiting almost two weeks, nothing arrived so we called them to see if they sent it yet. The representative said that the tin was on backorder and would not be shipped until June 20th! This afternoon we scoured the internet looking for any supplier that sold some chemical grade tin. There was no point looking up other large companies since I knew that they would take another week to send it. I ran across this company’s site, lo and behold, they sold mossy tin and they are based out of Exton, PA (which is about 30 mins from here, south of Phoenixville). After calling them up, they said we could buy some for $10/pound at 99.92% purity. A pound is about 450 grams, so we got about four times as much tin for a quarter of the cost (and with a better purity, who can argue with that deal?). Three cheers for a small business! Fisher’s main problem is that when we cancel our order tomorrow, they won’t notice. Our measly order was not important enough for them in the first place, or they would have contacted us about the backorder. It’s a shameful way to run a business. In other news, instead of twiddling our thumbs all week, we started purifying more nanotubes today. We want to start making more of the second step product now that we are more confident in what we are doing. That way we’ll have plenty sitting around in case something goes wrong. Tomorrow, I plan on doing the third step of the reaction, wish me luck! Also, I've added an Archives page to make this front page a little less cluttered. | | 5/29/06 | Results? It has been a full week of work, but we may have finally got something. We tried every kind of solvent to dissolve our nanotube product: DMF, toluene, cyclohexane, and diethyl ether. We wanted it to be in solution, or at least suspended, so that we could take a spectrum on our nice FT-IR instrument. Alas, none of them worked effectively. So we tried the OChem lab instruments again. I take back what I’ve said about them earlier. They are small, and they have their problems, but they got the job done! We managed to get a readable spectrum of the solid functionalized nanotubes from step 2 of our process that should confirm that the reaction was successful. We have yet to figure out how to move them form the spectrometer (maybe we can hook the machine up to the network somehow) so right now I’m just comparing the spectra of our reactants and products by hand. After I figure this out for sure, I can show everyone what I got. Hopefully, that will sometime this week if we all keep our fingers crossed. | | 5/22/06 | Summer Fellows Day 1 We had a productive first day of summer fellows where we attempted to take an IR of our product. Before the end of the year, we tried to do this with mixed results. There is this sweet new FT-IR (Fourier Transform Infrared, manufactured by Thermo) spectrometer in our lab, but the problem was that DMF dissolves the NaBr salt plates that we were using. We also tried an ATR (it uses diamond or some other kind of plates that don’t dissolve in IR) expansion accessory, but it didn’t fit into the machine. In fact, the accessory does not fit into any of the IR spectrometers in the building. Instead we used the small IR specs in our organic labs. With those spectrometers, one cannot move the data to a different computer, so what we ended up with was a small, unreadable spectrum that was so messy with background info that it was pointless to analyze. The good news of the day is that brand new CaF2 salt plates arrived that don’t dissolve in our solvent. So now we get to use the FT-IR in our lab. Since we got off to a slow start today, we decided to see what the solid spectrum looked like. We took a background scan with the plates and pure nanotubes and then got a spectrum of our product. The spectrum did not come out as we expected, so we are going to try taking a background of the plates by themselves tomorrow. As soon as I can, I will upload some analyzed spectra for you all to look at. |
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