Dear Patrick,
I see no problem for SAD phasing of your mixed I3C/SeMet crystals with
shelxc/d/e (i.e.using hkl2map or the new ccp4i2 gui). Just to the high
energy side of the Se edge at about 0.98A, f" for Se is about 3.8 and
for I about 3.2, so you would see both. On the low energy side of the
edge f" for I will still be about 3.2 but for Se it is much lower (about
0.5) so you might only see iodine. So if you collect data at these two
wavelengths and analyse both as SAD you get some useful extra
information. In practice the Se/I ratio could be higher if the I3C is
not fully occupied or the Se is partly oxidized and you hit a 'white line'.
Taking the different elements into account rigorously with
multi-wavelength data is more complicated, but should give even better
phases. This is usually performed using the program SHARP.
Best wishes, George
On 02/05/2016 10:27 AM, Patrick Pausch wrote:
> Hey folks,
>
> I’m currently working on a complex which shows increased crystallization and diffraction when co-crystallized with I3C (Iodine ligand). This is also true for the Se-methionine labeled variant. The iodine signal is usually accesible using CuKa radiation. I’m wondering if the anomalous signal of iodine (peak should be around 20 keV) will impede data processing after measuring selenium peak at synchrotron radiation source.
>
> Many thanks in advance!
>
> Patrick Pausch
--
Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-33021 or -33068
Fax. +49-551-39-22582
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