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Methods, Problems and Solutions

Powder Diffraction Structure Solution Pathways

Solving an Organic Structure (Cimetidine - C 10 H 16 N6 S) from Powder Diffraction Data

Solve the structure of Cimetidine using Dirdif fragment searching

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[Back to: Problems and Solutions] | [Back to: Tutorials]
[Back to: Powder Diffraction Structure Solution Pathways Index]
[Back to: Solving an Organic Structure (Cimetidine) from Powder Diffraction Data]

[Back to: Initial Connectivity Searching of the Cambridge database for Cimetidine like molecules using CORINA, Platon and Quest/CSD]
[Back to: Peak Profiling of Cimetidine using XFIT]
[Back to: Powder Indexing and Spacegroup Assignment of Cimetidine using the Crysfire and Chekcell combination of programs]
[Back to: CELL Searching the Cambridge database via Platon and Quest]
[Back to: Le Bail fitting and generating an EXPO starting file using LHPM-Rietica]
[Back to: Solve the structure of Cimetidine using the Sireware EXPO direct methods software]
[Back to: Finding possibly missing Symmetry in cimetidine using the Platon ADDSYM option]
[Back to: Searching the Cambridge database via Platon and Quest for related strutures]
[Back to: Generating a 2D to 3D fragement for fragment searching using the web based CORINA; then getting into a Shelx format using Ortep-3]
[Back to: Solve the structure of Cimetidine using Sir97 Single Crystal Direct Methods Software]
[Back to: Solve the structure of Cimetidine using Dirdif fragment searching]
[Back to: Solve the structure of Cimetidine using ESPOIR with no restraints]
[Back to: Solve the structure of Cimetidine using ESPOIR with bond restraints]
[Back to: Solve the structure of Cimetidine using ESPOIR with a combination of rigid bodies freely moving atoms]

[To: Xfit-Koalariet Peak Profiling Software] | [To: Crysfire Powder Indexing Suite] | [To: Chekcell Powder Indexing Helper Tool] | [To: Platon/System S Crystallographic Toolset] | [To: LHPM-Rietica Rietveld for Win95/NT] | [To: EXPO Directory Methods Structure Solution from Powder Data] | [To: Sir97 Single Crystal Structure Solution Software] | [To: WinGX Single Crystal Suite] | [To: Espoir Monte Carlo Structure Solution Software]

This example uses example Cimetidine data from the EXPO software


Another option to try and solve the structure is to use a fragment search technique as offered by Dirdif (and Patsee software).

Normally the main problem is to get a fragment is a format that is DIRDIF happy. Using the combination of Ortep-3, WinGX and (the soon to be released) SXGRAPH by Louis Farrugia of Glasgow University, this is quite trivial. It is important that the fragment being used in this case have the Sulphur as part of it or the Patterson fragment search could get quite confused if the heavy atom (being the Sulphur) is not part of the fragment.

The ability of Dirdif to solve on the fragment is dependent on how representative on the accuracy of fragment to be in the same conformation as it is in the structure.

Obtain a structure file that includes the bit of fragment that you wish to use. This can either be from the Cambridge database, a prior refined structure, or generating the fragment in CORINA from a 2D representation. Ortep-3 can then be used to import a variety of structure file formats and output a Shelx file.


Run WinGX, go into the directory with the HKL data and fragment (this assumes autostart has already been run and WinGX has the basic information on the sample) and select Refine, SXGRAPH.

SXGRAPH will have no structure in it as there is no solved structure for it to view. Now do File, Open SHELX File and select the Shelx file with the fragment.

SXGRAPH


Then select Delete, All Type, H atoms.

Deleting all the H atoms in the fragment


Use the Box Selection option to click and drag to select the flexible part of the fragment (not including the sulphur)

Selecting the flexible part of the fragment

Use the Delete, Selected Atoms to delete these atoms.

Deleting the flexible part of the fragment


Now save the Fragment into a Dirdif happy format using File, Save ATMOD.

Saving the fragment into a Dirdif happy format

DIRDIF ATMOD File

ATMOD
ATOM  C0       0.14787   1.88725   1.17975
ATOM  N0       1.68988  -0.10675   0.67875
ATOM  C0       0.53988   0.60925   0.48375
ATOM  C0       1.63888  -1.17575  -0.14325
ATOM  S0      -2.83212  -0.38475   0.03675
ATOM  C0      -0.17812  -0.05175  -0.44425
ATOM  N0       0.51888  -1.13675  -0.81225
ATOM  C0      -1.52513   0.35925  -0.97925
END

Now run Dirdif in fragment searching mode by selecting, Solve, DIRDIF, Orient (or enter the interactive mode).

Solving in Dirdif fragment searching mode


[Back to: Problems and Solutions] | [Back to: Tutorials]
[Back to: Powder Diffraction Structure Solution Pathways Index]
[Back to: Solving an Organic Structure (Cimetidine) from Powder Diffraction Data]

[Back to: Initial Connectivity Searching of the Cambridge database for Cimetidine like molecules using CORINA, Platon and Quest/CSD]
[Back to: Peak Profiling of Cimetidine using XFIT]
[Back to: Powder Indexing and Spacegroup Assignment of Cimetidine using the Crysfire and Chekcell combination of programs]
[Back to: CELL Searching the Cambridge database via Platon and Quest]
[Back to: Le Bail fitting and generating an EXPO starting file using LHPM-Rietica]
[Back to: Solve the structure of Cimetidine using the Sireware EXPO direct methods software]
[Back to: Finding possibly missing Symmetry in cimetidine using the Platon ADDSYM option]
[Back to: Searching the Cambridge database via Platon and Quest for related strutures]
[Back to: Generating a 2D to 3D fragement for fragment searching using the web based CORINA; then getting into a Shelx format using Ortep-3]
[Back to: Solve the structure of Cimetidine using Sir97 Single Crystal Direct Methods Software]
[Back to: Solve the structure of Cimetidine using Dirdif fragment searching]
[Back to: Solve the structure of Cimetidine using ESPOIR with no restraints]
[Back to: Solve the structure of Cimetidine using ESPOIR with bond restraints]
[Back to: Solve the structure of Cimetidine using ESPOIR with a combination of rigid bodies freely moving atoms]

[To: Xfit-Koalariet Peak Profiling Software] | [To: Crysfire Powder Indexing Suite] | [To: Chekcell Powder Indexing Helper Tool] | [To: Platon/System S Crystallographic Toolset] | [To: LHPM-Rietica Rietveld for Win95/NT] | [To: EXPO Directory Methods Structure Solution from Powder Data] | [To: Sir97 Single Crystal Structure Solution Software] | [To: WinGX Single Crystal Suite] | [To: Espoir Monte Carlo Structure Solution Software]

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