From: Lalor, Fergus (f.lalor$##$ucc.ie)
Date: Tue Nov 18 2003 - 09:17:09 EST
I seem to remember a conversation with our friendly local crystallographer
in which he mentioned that structure analysis via powder-pattern spectra was
a theoretical possibility but the impression that I got was that it will be
some time yet before it bcomes a practical alternative to single-crystal
work.
Regards -
Fergus
> ----------
> From: Jacob Zabicky
> Sent: Tuesday, November 18, 2003 13:25 PM
> To: Lalor, Fergus
> Subject: Re: ORGLIST:Sources of Helpful Hints for Growing X-ray
> Quality Crystals?
>
> Hello Lalor,
>
> Let's look at the problem from another point of view. Say, one cannot
> grow a good enough crystal for the single-crystal crystallographers.
> From the dayly experience of organic chemist, one can crystallize and
> then recrystallize to very high purity many compounds, but I surmise
> only few of them will be successfully grown to XRD quality.
>
> In principle, why cannot methods be developed for structural analysis,
> based on powder XRD, possibly aided by supplementary data from another
> technique. Getting high quality powder diffraction patterns with
> practically no instrumental broadening is no problem with some of the
> modern equipment in hand. I agree there are some problems like
> frequently having polymorphs in organic crystals, but that's also a
> problem with single crystals. Another problem may be anisotropy induced
> by some external factor, but that shouldn't be hard to overcome.
>
> All the best,
>
> Jacob
>
> On Saturday, Nov 15, 2003, at 15:33 Asia/Jerusalem, Lalor, Fergus wrote:
>
> > Over the course of my professional life X-ray crystallography has gone
> > from
> > being an exotic technique availed of by the priviliged few of my
> > colleagues
> > who had contacts in well-provided US or UK universities to being
> > almost as
> > routine as elemental analysis. Growing 'good' crystals for X-ray
> > analysis,
> > on the other hand still remains pretty much one of the Black Arts. I am
> > frequently approached by graduate students for advice on how best to go
> > about crystallising this or that new compound. I have a few favourite
> > tricks
> > of my own, of course, but I am at a loss to refer them to any published
> > compliation of techniques except for a brief article by P.G. Jones in
> > Chemistry in Britian, pp. 222-225 published in 1971 or later. (If
> > anyone
> > knows the full citation I'd be grateful to have it).
> >
> > With all that has been published on the techniques and results of X-ray
> > crystallography the scarcity of published information on techniques for
> > growing 'good' crystals - without which our crystallographer friends
> > would
> > have nothing to do - seems rather surprising. Am I mistaken - are there
> > sources of information of which I am unaware? Any advice on this topic
> > would
> > be most gratefully received.
> >
> > Regards -
> > Fergus
> >
> > P.S, My apologies if this message appears twice but - as of this
> > moment - it
> > looks as if the first posting got lost on its way to the list.
> >
> > Dr. Fergus John Lalor
> > Senior Lecturer
> > Department of Chemistry
> > University College
> > Cork
> > Ireland.
> > Telephone: 00353-21-4902317
> > Fax: 00353-21-4274097
> > _______________________________________________
> > ORGLIST - Organic Chemistry Mailing List
> > Website / Archive / FAQ: http://www.orglist.net
> > To post a message (TO EVERYBODY) send to everybody$##$orglist.net
> > To unsubscribe, send to everybody-request$##$orglist.net the message:
> > unsubscribe your_orglist_password your_address
> > List coordinator: Joao Aires de Sousa (coordinator$##$orglist.net)
> >
> ***************************************************
> Prof. Jacob Zabicky
> Institutes for Applied Research
> Ben-Gurion University of the Negev
> P. O. Box 653, Beer-Sheva, 84105, Israel
>
> Phone: +972-8-6461271; Fax: +972-8-6472969
> zabicky$##$bgumail.bgu.ac.il
> http://www.bgu.ac.il/IAR/Zabicky.htm
> -------------------------------------------------
> Private:
> P. O. Box 12366, Beer-Sheva, 84863, Israel
> Phone: +972-8-6496792
>
>
_______________________________________________
ORGLIST - Organic Chemistry Mailing List
Website / Archive / FAQ: http://www.orglist.net
To post a message (TO EVERYBODY) send to everybody$##$orglist.net
To unsubscribe, send to everybody-request$##$orglist.net the message: unsubscribe your_orglist_password your_address
List coordinator: Joao Aires de Sousa (coordinator$##$orglist.net)
This archive was generated by hypermail 2.1.4 : Wed Jan 14 2004 - 08:37:01 EST