Solving molecular crystal structures from laboratory X-ray powder diffraction data with DASH:: the state of the art and challenges

被引:74
作者
Florence, AJ
Shankland, N
Shankland, K
David, WIF
Pidcock, E
Xu, XL
Johnston, A
Kennedy, AR
Cox, PJ
Evans, JSO
Steele, G
Cosgrove, SD
Frampton, CS
机构
[1] Univ Strathclyde, Dept Pharmaceut Sci, Glasgow G4 0NR, Lanark, Scotland
[2] CrystallografX Ltd, Glasgow G1 3DX, Lanark, Scotland
[3] Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England
[4] Cambridge Crystallog Data Ctr, Cambridge CB2 1EZ, England
[5] Univ Strathclyde, Dept Pure & Appl Chem, Glasgow G1 1XL, Lanark, Scotland
[6] Robert Gordon Univ, Sch Pharm, Aberdeen AB10 1FR, Scotland
[7] Univ Durham, Dept Chem, Univ Sci Labs, Durham DH1 3LE, England
[8] AstraZeneca R&D, Loughborough LE11 5RH, Leics, England
[9] Pharmorphix Ltd, Cambridge CB4 0WE, England
关键词
D O I
10.1107/S0021889804032662
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The crystal structures of 35 molecular compounds have been redetermined from laboratory monochromatic capillary transmission X-ray powder diffraction data using the simulated-annealing approach embodied within the DASH structure solution package. The compounds represent industrially relevant areas ( pharmaceuticals; metal coordination compounds; nonlinear optical materials; dyes) in which the research groups in this multi-centre study are active. The molecules were specifically selected to form a series within which the degree of structural complexity (i.e. degrees of freedom in the global optimization) increased systematically, the degrees of freedom increasing with increasing number of optimizable torsion angles in the structural model and with the inclusion of positional disorder or multiple fragments ( counterions; crystallization solvent; Z' > 1). At the lower end of the complexity scale, the structure was solved with excellent reproducibility and high accuracy. At the opposite end of the scale, the more complex search space offered a significant challenge to the global optimization procedure and it was demonstrated that the inclusion of modal torsional constraints, derived from the Cambridge Structural Database, offered significant benefits in terms of increasing the frequency of successful structure solution by restricting the magnitude of the search space in the global optimization.
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页码:249 / 259
页数:11
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