Jul 312010

CRYSTALS v14.11 is available as a beta-test.

Many small changes in Regularise Replace thanks to a CRYSTALS workshop in Toulouse organised by Carine Duhayon and Laure Vendier.

Cif generator now properly includes esds on refined hydrogen bonds, has incrreased figure-fields for cell parameters, and appends constraint and restraint information as _iucr_ data items at end of cif.

Improved scaling of difference Pattersons – see forthcoming paper by Flack, Sadki, Thompson & Watkin.

Absolute configuration routine (based on PLATON with Ton Spek’s permission) extended to provide more diagnostics and additional data to be re-input as absolute-structure strengthening restraints (see paper by Flack et al. above).

Error tracking for “USE” files has been improved.

Collaboration with Ernesto Mesto (Dipartimento Geomineralogico – Università degli Studi di Bari) uncovered over-sights in the original 1979 code, which lost contributions when a twin component fell onto a centring absence. Difference maps with twinned data now seem to reveal hydrogen atoms very reliably.

Jul 292010

The ACA was held at the Sheraton Hotel in Chicago, IL.  Contributions from Chem. Cryst. include:

James Haestier, Amber L. Thompson, David J. Watkin, George C. Feast, Jeremy Robertson & Lee Page
Why is P21/n a Standard Non-Standard Space Group? (Poster)

Amber L. Thompson & David J. Watkin
Unpublishable” Data:  Does My R-factor Look Big in This? (Poster)

Amber L. Thompson
Absolute Structure Determination – Interpreting the Flack Parameter  (Presentation)

Jul 132010

Cryst. Rev. (2010), 16(3), 197-230.    [ doi:10.1080/08893110903483246 ]

X-ray single crystal structure analysis has become a gold standard for the determination of molecular geometry. The reliability of the technique is a triumph for science and technology working together. The uniqueness of well-crystalline material intrigued early natural philosophers, and their examinations, followed by the discovery of the diffraction of X-rays by crystals, led to the powerful technology that we now enjoy. For about three quarters of a century molecular structure determination has been a driving force for crystallographic research, but now that the science has matured into a technology, interest is returning in trying to understand the nature of crystals themselves.

Jul 012010

There is some really cool chemistry done in Oxford and some even cooler structures.  In order to encourage everyone to take an interest in what other people are doing with our instruments, we have instigated a “Structure of the Month”.  The idea is that users submit a single-crystal structure that they have done (either here or at Diamond/ISIS).  This is done by filling in a form including a short explanation of why it is cool and we will choose the best submission and stick it up in the lab in an obvious place.

The rules are as follows:

In order to keep it current, the structure must have been collected in the previous two months, i.e. the structure for October must have been collected in August or September (or where the work is particularly sensitive, “accepted for publication” in the previous month).

  • The competition is only open to affiliates of Oxford Chemistry
  • We must receive it by email before the end of the previous month, i.e. submissions for October must be received by the end of September.
  • You must include a colour picture.
  • The description must be 100 words or less (we are very strict about this).
  • It must be cool to you, but it can be cool for any reason (see below).
  • The Judges’ decision is final.

You should include a covering comment explaining why it is cool to you.  We will accept most reasons, but examples include:

  • “It’s taken me three years to make it, 200 attempts to crystallise it and 10 days of data collection time, but we got it in the end.”
  • “We crystallised Vac Grease!”
  • “It has an R1 < 1%” (or even “it has an R1 > 35%”).
  • “How on earth did we make that???”
  • “We got an invitation to Stockholm to collect an award because of it…”
  • “I’ve collected 300 datasets and done structures for everyone else in my group, but this was the first one for me.”
  • “It is the first/longest/largest/… example of…”
  • “It’s just a cool molecule”.

If we have no submissions for one month, we will look back over submissions for the previous month and earlier until we find something suitable.

The decision will be based on “coolness”, but we will endeavour to ensure that there is plenty of variety too.  The Judges’ decision is final.  In time, there will be a small trophy that the winner can look after for a month while they are the holder.  For confidentiality reasons, the winning entry will be displayed at the entrance to Chem. Cryst. and will only be reported on the website once it has been published.

Please stick to the template and keep it to a single full page as in the example.  Email submissions to Dr. Amber L. Thompson by the end of the month; late submissions will be entered for the following month.