> I have a problem with the structural data for Ranitidine Hydrochloride
> (C13H23N4O3S-Cl), a pharmaceutical drug material. It is well known that it
> appears in two polymorphous: Form 1 and Form 2. Only the former one has
> therapeutic features. The only sructural data that I found in Cambridge
> Database are for Form 2 (Ishida & Inoue, Acta Cryst.-C, 1990, 46, 1893. It
> is monoclinic, P21/n. Does someone know any structural data for Form 1? I
> indexed the pattern with VBTreor (PowderX, Dong, 98) and it seems that Form
> 1 is also minoclinic, P-type. I am afraid that it will be quite difficult to
> solve the structure of Form 1 from X-ray powder data only, but if I have not
> any other choice, I can try. Any advise?
>
> Srebri
>
> /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
>
> Dr. Sr. Petrov/PXRD Analyses,
> Dept. of Chemistry, U of T,
> 80 St.George Str., R.417
> Toronto ON M5S 3H6, Canada
> Tel/Fax: (416)-978-1389.
> e-mail: [EMAIL PROTECTED]
>
Not sure if the following opinion is unfair and corrections appreciated :
But at least up until the above mentioned workshop at Glasgow, trying
to solve structures from powder at the press of a button is pretty much
a one dog trick in terms of freely available software for
academics - Direct Methods/Pattersons(?)
However, has the above been tried?
Available direct methods software optimised for
powders, EXPO (sequel to EXTRA and Sirpow) for Windows,
UNIX and VAX from the Sirware group could be a goer and
is freely available for academic users
(after you sign the registration forms and mail/fax).
http://www.ba.cnr.it/IRMEC/SirWare_main.html
http://www.ccp14.ac.uk/ccp/web-mirrors/sirware/IRMEC/SirWare_main.html
---
The example given with EXPO is that of synchrotron data on
cimetidine.
cont s 4 c 40 n 24 h 64
wave 1.52904
cell 10.6986 18.8181 6.8246 90.000 111.284 90.000
space p 21/n
Runthrough of how easy this can/possibly be done with EXPO is
viewable via:
http://www.ccp14.ac.uk/tutorial/expo/index.html
----
The Tetracycline hydrochloride in previous mentioned
messages was also solved by one participant doing a Patterson;
manually finding the Chlorine which was enough to
build up the rest of the structure with difference maps.
Might this be a possibility - try a patterson
on the Heavy atoms? Dirdif can be quite excellent both
performing and interpreting a Patterson and then
trying to expand the structure - though again it is a
single crystal program.
http://www-xtal.sci.kun.nl/xtal/documents/software/dirdif.html
http://www.ccp14.ac.uk/ccp/web-mirrors/dirdif/xtal/documents/software/dirdif.html
ftp://ftp.minerals.csiro.au/pub/xtallography/ccp14/ccp/web-mirrors/dirdif/xtal/documents/software/dirdif.html
A Windows version of Dirdif is also on the below mentioned
WinGX site.
----
Also there is Armel's tutorial for solving structures to
go through some of the tricks:
http://fluo.univ-lemans.fr:8001/iniref/tutorial/indexa.html
http://www.cristal.org/iniref/tutorial/indexa.html
http://www.ccp14.ac.uk/ccp/web-mirrors/armel/iniref/tutorial/indexa.html
ftp://ftp.minerals.csiro.au/pub/xtallography/ccp14/ccp/web-mirrors/armel/iniref/tutorial/indexa.html
Plus for the Patterson as well as the direct methods route,
WinGX can be quite good as an interface
for plugging the extracted intensity data
into various single crystal solution programs - Shelxs,
Dirdif, Sir92/Sir97.
http://www.ccp14.ac.uk/tutorial/wingx/powder/index.html
Lachlan.
--
Lachlan M. D. Cranswick
4th Jan - 16th March 1999 Visiting Scientist
CSIRO Division of Minerals, Melbourne, Australia
Tel: (613) 9545 8500 (switch)
Fax: (613) 9562 8919 [EMAIL PROTECTED]
Collaborative Computational Project No 14 (CCP14)
for Single Crystal and Powder Diffraction
Daresbury Laboratory, Warrington, WA4 4AD U.K
Tel: +44-1925-603703 Fax: +44-1925-603124
E-mail: [EMAIL PROTECTED] Ext: 3703 Room C14
NEW CCP14 Web Domain (Under heavy construction):
http://www.ccp14.ac.uk
