Time flies ……

I’m a bit over halfway through my summer research period, and I’m pretty impressed with how quickly the time has passed. I guess 10 weeks isn’t quite as long as I first thought!

The synthetic portion of my project has moved forward very quickly – and grown quite a bit since the start of the summer. The types of N-aromatic systems that are used in the organic cation have been extended to include larger pi systems than pyridine – these shown in the picture below. So far, this extension includes N-alkylated versions of quinoline, acridine, and 4, 4’ bipyridyl (which, IMHO, has the fun abbreviation 4, 4’ bpy), but the list is still growing. Additionally, I’m also trying to synthesize cations with electron withdrawing groups substituting the aromatic system – i.e, compounds like N- alkylated cyanopyridine. The rationale behind this extension is that by substituting the pi (aromatic) system – pyridine in the example above – with a electron withdrawing group, the cation as a whole will act as an even better electrophile, with a lower energy LUMO (lowest unoccupied molecular orbital). The hope is that the lower energy LUMO (or acceptor) orbital will decrease the energetic gap between our donor CuI cluster HOMO and the cation based LUMO, which will increase the conduciveness of our system to some type of intersystem (i.e, anion to cation) charge transfer.

N- Alkylated pi systems

The crystallographic portion of the project is also progressing quite quickly – I now have whole structures of about 10 [XY][CuI2] (Y = nitrogenous aromatic system) salts, with many, many more to crystallize. The preliminary results of this series of structures suggest that there is some structural diversity within the smaller cation salts. However, this diversity fades as the cation grows larger, to the point where over half of the structures characterized (so far) crystallize with the same [CuI2] anion. This is actually a pretty interesting (albeit preliminary) result – oftentimes, there is  a large amount of structural diversity within CuI clusters, even when cations and reaction conditions used to prepare said salts are similar. The constancy in the CuI anion’s structure provides something of a point of reference for the series of salts as a whole, and will be invaluable once there’s enough of a sample size of structures to (hopefully) draw some conclusions about the relationship between the salt series’s structure and luminescence.

On a more personal note, the part of this  research experience that has had the greatest impact on me so far is that I am continually struck by how much more there is to learn about, well, pretty much everything. At the risk of angering all English majors with the following play on a cliché, I learn something new every day. Sometimes it’s as practical as seeing a better way to perform a technique, sometimes it’s hearing an interesting fact about the reactivity of a compound I’m working with,  and sometimes it’s simply stumbling upon a concept that I never knew existed. Oftentimes its all the above. Even with a good portion of the research period to go, I already know that one of the lessons that I will take away from it is a new understanding of the advice to “never stop learning”.

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