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Topic: crystallography q's  (Read 4732 times)

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crystallography q's
« on: November 13, 2005, 04:00:03 AM »
does a substance have to be 100% crystalline in order to perform an X-ray crystal structure determination?  What if there are two compounds in your crystal? and lastly, does anyone know of any single crystalline polymers?

Offline sdekivit

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Re:crystallography q's
« Reply #1 on: November 13, 2005, 03:06:33 PM »
2 compunds can be analyzed with X-ray diffraction, think about the interaction between an enzyme bound it's ligand. The interaction between these two molecules can be examined with this technique.


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Re:crystallography q's
« Reply #2 on: November 13, 2005, 03:20:02 PM »
an interesting point sdekivit and not one that I had originally aniticipated.  You are correct, of course, but I was talking more along the lines of an impurity. So, two compounds which crystallize together to form a lattice.

Offline AWK

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Re:crystallography q's
« Reply #3 on: November 14, 2005, 02:00:34 AM »
Substance that can be examined by X-ray should be crystalline, but it does mean 100 %. There are many substances that are disordered, and its structure can be solved. At the moment I am doinh with substancet that show 25 % of disorder (measured as scattering power for X-ray) and they be solved without any trouble
(but their refinemet is horrible).
Crystalline polymers are always disordered in some extent

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