Re: [sdpd] Bethanechol chloride : new single crystal results
Easy to find a lot of published restrained refinements. Easy to restrain, thus easy to find - nobody doubts. Sorry to destroy your unrestrained future. Don't worry: even Armel Le Bail can't destroy the future. Unrestrained refinement is possible yet for such ugly data: http://sites.google.com/site/ddmsuite/home/dithianon_I-DDM.cif http://sites.google.com/site/ddmsuite/home/dithianon_I-DDM.png The precision here is much lower than in the previous example, but it might have been improved if the authors of that nice paper had spent more time for data collection and/or sample preparation. *** Leonid A. Solovyov Institute of Chemistry and Chemical Technology 660049, K. Marx 42, Krasnoyarsk, Russia http://sites.google.com/site/solovyovleonid *** From: Armel Le Bail armel.le_b...@univ-lemans.fr To: s...@yahoogroups.com Sent: Wednesday, September 4, 2013 8:01 PM Subject: Re: [sdpd] Bethanechol chloride : new single crystal results Unrestrained future can't be destroyed. Being restrained, however, it destroys itself. Easy to find a lot of published restrained refinements. Four examples in that nice 2012 paper : http://scripts.iucr.org/cgi-bin/paper?S0108768112036191 Data available. No. of parameters 106 129 260 177 No. of restraints 65 65 204 139 Sorry to destroy your unrestrained future. Best, Armel++ Please do NOT attach files to the whole list alan.he...@neutronoptics.com Send commands to lists...@ill.fr eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
Re: [sdpd] Bethanechol chloride : new single crystal results
Dear Armel, From the comparison of your distances and angles with the single-crystal ones, two obvious conclusions can be drawn: 1) Applying a simplified refinement model one can't expect accurate results 2) Uncertainty estimations in Rietveld programs are inadequately optimistic Here you may see unrestrained DDM results for this structure: http://sites.google.com/site/ddmsuite/tutorials/bethcl-DDM.cif http://sites.google.com/site/ddmsuite/tutorials/bethcl-DDM.png I used synchrotron data (10-years old) from: http://sdpd.univ-lemans.fr/uppw/bethanechol.zip The main problem was in a complex anisotropic and asymmetric peak broadening that you mentioned in your publication. I modeled it by including two pseudo-phases with variable lattice parameters. The resulted distances and angles agree with the single-crystal ones within 3 e.s.u.: Single-crystal DDM C2 O4 1.359(4) 1.356(9) O4 C5 1.454(4) 1.473(7) O1 C2 1.217(4) 1.200(11) C2 N3 1.338(5) 1.331(10) C5 C6 1.521(5) 1.518(7) C5 C7 1.522(5) 1.530(8) C7 N8 1.516(4) 1.534(7) N8 C9 1.501(5) 1.512(7) N8 C10 1.496(4) 1.495(8) N8 C11 1.499(5) 1.491(8) C2 O4 C5 116.6(3) 116.5(5) O1 C2 O4 123.4(3) 123.5(7) O1 C2 N3 125.4(3) 127.2(7) N3 C2 O4 111.1(3) 109.3(7) O4 C5 C6 108.1(3) 107.2(5) O4 C5 C7 110.2(3) 109.3(5) C6 C5 C7 109.3(3) 108.0(4) N8 C7 C5 117.6(3) 117.1(4) C9 N8 C7 107.3(3) 107.6(4) C10 N8 C7 111.8(3) 110.8(5) C11 N8 C7 112.1(3) 112.6(4) C10 N8 C9 108.1(3) 107.8(4) C11 N8 C9 107.3(3) 108.9(4) C10 N8 C11 110.0(3) 109.0(4) The C-C precision is 0.0075 A, reasonably comparable to the single-crystal 0.005 A. The results can be further improved if the available XRD pattern is not interrupted at 26.8 degrees and/or if the sample is better prepared. So, the unrestrained SDPD future exists and it is much more interesting. Best regards, Leonid *** Leonid A. Solovyov Institute of Chemistry and Chemical Technology 660049, K. Marx 42, Krasnoyarsk, Russia http://sites.google.com/site/solovyovleonid *** From: Armel Le Bail armel.le_b...@univ-lemans.fr To: s...@yahoogroups.com Sent: Tuesday, September 3, 2013 3:53 PM Subject: [sdpd] Bethanechol chloride : new single crystal results Hi, For those especially interested in comparing unrestrained SDPD results with single crystal ones a new example is available, BC (bethanechol chloride) which was one of the 2003 UPPWs Unindexed Powder Pattern of the Week : http://sdpd.univ-lemans.fr/uppw/index.html UPPW-11 : http://sdpd.univ-lemans.fr/uppw/uppw11.html It was extensively used for testing various indexing sofware and proposed for benchmarking (2004) : http://www.degruyter.com/view/j/zkri.2004.219.issue-12-2004/zkri.219.12.783.55862/zkri.219.12.783.55862.xml;jsessionid=5297B32E4713E27A7B5A9DAB82D2ACE6 http://sdpd.univ-lemans.fr/uppw/benchmarks/ SDPD published in 2010, restraints on H only, 298 K : http://journals.cambridge.org/action/displayAbstract?fromPage=onlineaid=8481214 Single crystals finally synthesized, structure published in 2013 (123 K) : http://pubs.rsc.org/en/Content/ArticleLanding/2013/CE/c3ce40707a Results said to be in agreement. Best, Armel Le Bail __._,_.___ Reply via web post Reply to sender Reply to group Start a New Topic Messages in this topic (1) Recent Activity: Visit Your Group Switch to: Text-Only, Daily Digest • Unsubscribe • Terms of Use • Send us Feedback . __,_._,___ ++ Please do NOT attach files to the whole list alan.he...@neutronoptics.com Send commands to lists...@ill.fr eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
Re: [sdpd] Bethanechol chloride : new single crystal results
A good chemist is able to destroy any SDPD future. Unrestrained future can't be destroyed. Being restrained, however, it destroys itself. The low-temperature single-crystal refinement doesn't eliminate the necessity for accurate room-temperature structural data that may be required for QPA, e. g. *** Leonid A. Solovyov Institute of Chemistry and Chemical Technology 660049, K. Marx 42, Krasnoyarsk, Russia http://sites.google.com/site/solovyovleonid *** From: Armel Le Bail armel.le_b...@univ-lemans.fr To: s...@yahoogroups.com Sent: Wednesday, September 4, 2013 4:55 PM Subject: Re: [sdpd] Bethanechol chloride : new single crystal results So, the unrestrained SDPD future exists and it is much more interesting. OK, your synchrotron results are more in agreement with the single crystal ones than my laboratory data refinement (unrestrained also...) which is only in agreement. Anyway, the unique authority is that of the single crystal result... The logical benefit of non-overlapping three-dimensionnal data. A good chemist is able to destroy any SDPD future. That 2013 good chemist was long awaited in the bethanechol chloride case. Note that he was not able to obtain the orthorhombic phase, though. so that all is not solved yet. There is another polymorph clearly shown in the 2010 paper. Finally, maybe I should try to solve it in spite of the fact that it is always mixed with the monoclinic phase ? Or you should try. But the data are only routine powder patterns... Best, Armel __._,_.___ Reply via web post Reply to sender Reply to group Start a New Topic Messages in this topic (3) Recent Activity: Visit Your Group Switch to: Text-Only, Daily Digest • Unsubscribe • Terms of Use • Send us Feedback . __,_._,___ ++ Please do NOT attach files to the whole list alan.he...@neutronoptics.com Send commands to lists...@ill.fr eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
