The 2009 Annual Meeting of The American Crystallographic Association

Abstract

The American Crystallographic Association held its 2009 annual meeting 24–30 July in Toronto, Ontario, Canada. It was the third largest meeting ever, with 898 attendees from 29 countries; 59% of the attendees were from the US and 23% from Canada. Despite the perception that this is a macromolecular crystallography conference, there were at least two and most of the time 3 parallel materials/ small-molecule sessions throughout the meeting. There were 226 oral presentations and 362 posters. A highlight of the meeting for me was the unusual 2-day workshop on solving using charge flipping and refining incommensurate crystal structures using Jana2006. Vacav Pet i ek, Michal Dusek, Manual Perez-Mato, and Olivier Gourdon lectured, but most of the time was spent hands-on, refining 3d, simple and complex 3+1 d structures using both single crystal and powder data. About 40 of us worked hard and learned a lot! Another 1-day workshop on Handling Twinning in Macromolecular Crystallography led by George Sheldrick was very popular. As always, there was too much science for any one person to cover, so this summary is highly idiosyncratic. Sessions on General Interest and Energy-Related Materials ran simultaneously. In the first, Andreas Lemmerer Ben Gurion University of the Negev showed how careful use of the hot stage microscope yielded single crystals of polymorphs of pyrithyldion and isopropylphenazone, crystals which could be used to determine the structures. A thin layer of grease on the microscope facilitated isolation of the crystals. In the second, Haiyan Chen New Jersey Institute of Technology and NSLS carried out a time-resolved in situ study of the formation of the modulated thermoelectric phase Ca3Co4O9. The phase transitions and kinetics were characterized at beamline X14A. An important session for readers of this journal was that on Accuracy and Standards in Powder Diffraction, organized by Pam Whitfield. Jim Cline NIST described in detail the three factors in the preparation of a NIST SRM: the artifact, the instrumentation, and theory and data analysis. Silicon 640d is now available, as well as the set 674b, alumina powder 676a, and the alumina plate 1976a, and LaB6 660b should be available in 6 months. The amorphous content in a crystalline solid can be characterized by varying the concentration of the impurity systematically say, by varying the particle size and extrapolating. Lutz Brugemann Bruker AXS summarized the engineering that goes into a diffractometer, as well as systematic errors. Oladipo Omotoso Natural resources Canada, and a past winner of the Reynolds Cup showed how clays minerals represent a real challenge and opportunity of quantitative phase analysis. He described a new technique for producing randomly-oriented specimens, and showed that, starting with good structural models, both full-pattern fitting methods