Disappearing polymorphs

 [[{“value”:”Here’s a wild phenomena I wasn’t previously aware of: In crystallography and materials science, a polymorph is a solid material that can exist in more than one crystal structure while maintaining the same chemical composition. Diamond and graphite are two polymorphs of carbon. Diamond is carbon crystalized with an isometric structure and graphite is carbon
The post Disappearing polymorphs appeared first on Marginal REVOLUTION.”}]] 

Here’s a wild phenomena I wasn’t previously aware of: In crystallography and materials science, a polymorph is a solid material that can exist in more than one crystal structure while maintaining the same chemical composition. Diamond and graphite are two polymorphs of carbon. Diamond is carbon crystalized with an isometric structure and graphite is carbon crystalized with a hexagonal structure. Now imagine that one day your wife’s diamond ring turns to graphite! That’s unlikely with carbon but it happens with other polymorphs when a metastable (locally) stable version becomes seeded with a stable version.

The drug ritonavir originally used for AIDS (and also a component of the COVID medication Paxlovid), for example, was created in 1996 but in 1998 it couldn’t be produced any longer. Despite the best efforts of the manufacturer, Abbott, every time they tried to create the old ritonavir a new crystalized version (form II) was produced which was not medically effective. The problem was that once form II exists it’s almost impossible to get rid of it and microscopic particles of form II ritonavir seeded any attempt to create form I.

Form II was of sufficiently lower energy that it became impossible to produce Form I in any laboratory where Form II was introduced, even indirectly. Scientists who had been exposed to Form II in the past seemingly contaminated entire manufacturing plants by their presence, probably because they carried over microscopic seed crystals of the new polymorph.

Wikipedia continues:

In the 1963 novel Cat’s Cradle, by Kurt Vonnegut, the narrator learns about Ice-nine, an alternative structure of water that is solid at room temperature and acts as a seed crystal upon contact with ordinary liquid water, causing that liquid water to instantly freeze and transform into more Ice-nine. Later in the book, a character frozen in Ice-nine falls into the sea. Instantly, all the water in the world’s seas, rivers, and groundwater transforms into solid Ice-nine, leading to a climactic doomsday scenario.

Given the last point you will perhaps not be surprised to learn that the hat tip goes to Eliezer Yudkowsky who worries about such things.

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 Medicine, Science