On how far and how fast things go

I fell prey to the dictum I preach in my classes… I often say something along the lines of: “Chemistry is more or less about how far a system can go and how fast it can do it. In our craft we ought to control both”. Of course, I refer to the thermodynamic / kinetic control. I wonder how many students have heard me say it over the years and got fed up hearing it…

ddd

The image above is not an exoplanet or our Earth’s moon viewed from some haystack. It is a photo of an exciting macrocycle which has, as you can see, crystallized. The crystals emerged as a result of a painful process that involved me setting up 1056 experiments.  What you see is an expanded view of our typical 3mm-in-diameter well. The most frustrating thing is that these crystals, albeit needle-like and imperfect, vanished within 24 hours. It is interesting that the crystals formed fast (kinetics were favorable), but eventually disappeared due to their instability. Fortunately, we do have the Le Chatelier principle in our disposal and my next steps will be to repeat the experiment and preclude the reverse from happening. Since this is a vapour diffusion-type method (with water ruling the gas phase), I will need to carefully play tricks with the other reservoir. This is a very precious molecule, though. All 0.02mgs of it. Stay tuned.

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