On Monday, I started my day by checking on a calculation I did on a molecule called acetyl acetone. I got to design this molecule before sending it off for calculation in a pretty slick program called ECCE:
(excuse the low-res photo; Blogger does things which I do not understand)
Working with this program is, admittedly, the most fun I've had on this project thus far. You basically have the ability to craft any molecule you could possibly think of and run it through a supercomputer in order to determine its bond angles, bond lengths, interactivity with other molecules, and so fourth. I've probably mentioned it before, but I will again: it allows you to play God.
While that sounds fun and all, there is still work to be done. Long story short, the form of acetyl acetone (acac) that I input into the supercomputer is unfortunately not in its most energetically stable state. The most stable state of acac (at room temperature, anyway) is in a form that involves a hydrogen bond that mimics a five-member ring. In other words, instead of putting in the thing on the right, I put in the thing on the left, depicted in the picture below:
The configuration on the right is what actually happens in real life at room temperature. I didn't figure this out until I compared the output of my earlier calculation with actual X-ray crystallography data. That being said, I now have to figure out how to represent the structure on the right in a form that computers can understand. It isn't as easy as simply entering it into the program due to a couple phenomena, namely electron delocalization and electron pushing, so I'll need to find another way. A good portion of the remainder of my week will be spent doing exactly that.
Now, onto the lab work. A lot has happened here since Monday as well. We arrived in the lab to find that Eu(Tta)3(H20)2, the other molecule I was working on, had not recrystallized at all since we last left it in the lab. When we took it out of the freezer, it appeared to be a honey-like thing that wasn't terribly useful. Nonetheless, we moved forward with reacting it with TPTZ, a final ingredient to the concoction that increases the quantum yield (efficiency) of the luminescence of the compounds. We let it react for a little over two days to get a final product, which we've split into two portions for two different recrystallization methods. One method involves placing a tissue over the ampule that contains the compound and allowing it to evaporate slowly. The other involves concentrating the solution by letting evaporate quickly to half its volume, then allowing for it to finish its recrystallization in a refrigerator. Seeing as how we've been having so much difficulty obtaining pure product from our reactions in general, having two reaction vessels has allowed us to have a "Plan A" and "Plan B" for recrystallization. This is a good thing.
As far as Eu(DBM)3TPTZ is concerned, after letting its solvent evaporate, we obtained an oily yellow substance that didn't really yield any crystals. (Remember: obtaining crystals is important because crystals are much more likely to be free of impurities from side-reactions than are anything else.) So, we've decided to dissolve it in acetonitrile (which is like acetone, except one-half of it is a triple-bonded nitrogen instead of a methyl group) and layered it with ethanol as an antisolvent. Ethanol doesn't really dissolve the Eu(DBM)3TPTZ compound, which is a good thing -- by forcing Eu(DBM)3TPTZ into a solid form, it wouldn't be difficult to filter it out and from there separate it using a filtration method. After all, that's the compound we want.
I think that's everything. Of course, I'll probably remember something I didn't mention a couple hours from now. But either way, I'm beginning work on writing my eventual lab report. There's a TONNN of theory in comparison to procedural matters, but what with the fantastic preparation I've had with Mr. Mathews and Mr. Lee in writing lab reports, I'm not worried at all.
All the best,
--Dany.
Now, onto the lab work. A lot has happened here since Monday as well. We arrived in the lab to find that Eu(Tta)3(H20)2, the other molecule I was working on, had not recrystallized at all since we last left it in the lab. When we took it out of the freezer, it appeared to be a honey-like thing that wasn't terribly useful. Nonetheless, we moved forward with reacting it with TPTZ, a final ingredient to the concoction that increases the quantum yield (efficiency) of the luminescence of the compounds. We let it react for a little over two days to get a final product, which we've split into two portions for two different recrystallization methods. One method involves placing a tissue over the ampule that contains the compound and allowing it to evaporate slowly. The other involves concentrating the solution by letting evaporate quickly to half its volume, then allowing for it to finish its recrystallization in a refrigerator. Seeing as how we've been having so much difficulty obtaining pure product from our reactions in general, having two reaction vessels has allowed us to have a "Plan A" and "Plan B" for recrystallization. This is a good thing.
As far as Eu(DBM)3TPTZ is concerned, after letting its solvent evaporate, we obtained an oily yellow substance that didn't really yield any crystals. (Remember: obtaining crystals is important because crystals are much more likely to be free of impurities from side-reactions than are anything else.) So, we've decided to dissolve it in acetonitrile (which is like acetone, except one-half of it is a triple-bonded nitrogen instead of a methyl group) and layered it with ethanol as an antisolvent. Ethanol doesn't really dissolve the Eu(DBM)3TPTZ compound, which is a good thing -- by forcing Eu(DBM)3TPTZ into a solid form, it wouldn't be difficult to filter it out and from there separate it using a filtration method. After all, that's the compound we want.
I think that's everything. Of course, I'll probably remember something I didn't mention a couple hours from now. But either way, I'm beginning work on writing my eventual lab report. There's a TONNN of theory in comparison to procedural matters, but what with the fantastic preparation I've had with Mr. Mathews and Mr. Lee in writing lab reports, I'm not worried at all.
All the best,
--Dany.
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