Post 1: Grinding Studies

For the few days I worked with Polyacrylonitrile as a potential substrate for work with CuI. The most promising results came from stirring the suspended PAN in a 5M KI solution with CuI dissolved within. AA results from this study gave a maximum coordination of active sites by copper at around 2%. These numbers were so meager that we decided to discontinue our efforts on that portion of the project.

For the majority of the rest of first of half of the summer, I made a variety of CuI substrate complexes by physically grinding equimolar amounts of CuI and my substrate in a mortar and pestle.

Then, the same grinding experiment was repeated but rather than dry grinding, the substituents were ground under a couple drops of acetonitrile. Powders were run on most of these samples before and after the acetonitrile treatment. This helped determine the degree to which they had reacted without the aid of acetonitrile and then with the aid of the acetonitrile. A representative sample of these “average” powder results are shown below:

number 1

As can be seen by the increased size of non-CuI peaks and diminishing of CuI peaks, grinding in acetonitrile often resulted in a greater degree of coordination between the CuI and the ligand. Once all the compounds had been ground in acetonitrile, photos were taken of each compound under blacklight. The grand overview of these results is depicted in following figure:

number 2

Several general trends can be parsed from these results. Firstly, it seems that having a functional group be in 2-position of the pyridine tends to result in lower emission intensity, which can be seen in compounds like the 2ClPy, 2BrPy, 2MeOPy, and 2MeCOPy compounds. Second, it seems that aliphatic amines also have a lower emission then their pyridine derivative counterparts.

Using this overview as a guide, several compounds were picked to be further studied and have their authentic compounds synthesized. These compounds were the 2ClPy, 2MeCOPy, HMTA, NPh3, 3HOPy, 4HOPy, and 4COOHPy. For some of the water-soluble ligands good results were achieved simply by the KI method which involves making a 5mL aqueous solution of 5M KI then dissolving 1.5mmol CuI(315mg) then slowly adding in 1mL of an aqueous solution with 2mmol of the ligand dissolved.

For less water-soluble ligand, the 2mmol of ligand was first dissolved in 1mL of ethanol. Then into a 5mL aqueous solution of 5M KI was dissolved 1.5mmol CuI(315mg). Finally, the ethanol ligand solution was slowly added to the a 5mL KI solution.
Some compounds had difficulties because they would dissolve quite readily when washed in ethanol and acetone. For those, a 2.5mmol of the ligand was dissolved in 5mL of 95% ethanol and 2mmol of solid CuI was added and stirred for several days. The results of this last method is questionable but still holds promise for some ligands. Depicted below is a powder pattern from this unconventional EtOH methods which clearly shows that very little unreacted CuI remains from this method.

number 3

Ligand/Method AA result AA theoretical Promise(1-5)
Ph3N/KI NA   2
HMTA/KI 23.56 19.2 2
HMTA/KI 2nd attempt NA 19.2 3
3HOPy/KI 9.559 22.2 1
4COOHPy/KI 22.85 20.3 4
2MeOCPy/KI 22.94 20.4 4
2ClPy/KI 36.33 20.9 1
2ClPy/KI EtOH NA 20.9 2
3HO Py/ EtOH NA 22.2 2

 

This summarizes the AA results of my attempts to make authentic compounds and their promise with scores 1-5 having an ascending amount of promise