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Polymorphisms, Cocrystals, and Salt Selection - differences?

  1. Jun 13, 2013 #1


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    *This is not homework, I'm a technical writer.

    I'm trying to understand how these terms are related and different. Here's what I have concluded so far:

    Wikipedia definition is that cocrystals “consist of two or more components that form a unique crystalline structure having unique properties."

    Wikipedia definition of Polymorphisms is the ability of a solid material to exist in more than one form or crystal structure.

    But then, there are polymorphisms in co-crystals too...

    Now salt selection would just mean selecting a particular polymorph or cocrystal?

    It's a little confusing to me, any help?

    Thanks, David
  2. jcsd
  3. Jun 23, 2013 #2
    Hi, the term co-crystal sounds a bit odd to me and I am a materials scientist. It looks it is used a lot in organic chemistry, although I can think of a number of inorganic crystalline materials that fit in the description given in Wikipedia. It is a just a new compound obtained by crystallizing together two (or why not more) other crystalline compounds. Polymorphism means that a substance can crystallize in more than one crystalline form, so that should apply to some co-crystals too. "Salt selection" is not any particular scientific term so you should give us more info about the context, to help us find the relationship with co-crystals. Just a guess, it seems there is a quest to develop new co-crystals and that is achieved by selecting appropriate materials to crystallize together. Probably salts can be also used for this purpose.
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