PLATON TUTORIAL A.L.Spek, National Single Crystal Service Facility, Utrecht, The Netherlands.
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Transcript of PLATON TUTORIAL A.L.Spek, National Single Crystal Service Facility, Utrecht, The Netherlands.
PLATON TUTORIAL
A.L.Spek,
National Single Crystal Service Facility,
Utrecht, The Netherlands.
Who Are We ?
• We, a small group of 3 to 4 people run a National Single Crystal Service in the Netherlands since 1971 (Utrecht University).
• (Bruker)Nonius KappaCCD on Rotating Anode + Oxford LNT + UNIX/LINUX Computers.
• Over 3000 structures studied so far, about 1800 published in over 1100 papers.
• Mainly organometallic and coordination chemistry• Main Software: P.D. SHELX + PLATON• Co-Editor Acta Cryst. C (> 850 papers handled)
Tutorial Program
• 1 PLATON Overview Presentation
• 2 Life PLATON Demonstration (Linux)
• 3 Hands-on Exercises (MS-WINDOWS)
• 4 Lecture on Structure Validation
What is PLATON
• A Multipurpose Crystallographic Tool.• Developed in a Single Xtal Service Environment.• Compatible with and Complementary to the
Public Domain SHELX & Bruker-AXS SHELXTL Software.
• ‘Public domain’ (I.e. free-of-charge for academics, License Fee for For Profit Organizations).
• Available on UNIX/LINUX, MS-Windows & MAC-OSX Platforms.
Multipurpose Crystallographic Tool
• Automatic Geometry Analysis & Listing.• Molecular Graphics (PLUTON, ORTEP, Contour)• Absorption Correction Tools(MULABS,TOMPA)• ADDSYM - Check for Missed Symmetry.• SQUEEZE – Disordered Solvent Handling.• Generation of Powder Patterns.• Structure Validation (part of IUCr CHECKCIF).• Analysis of Fo/Fc data including Bijvoet Pairs.• System-S, Automated Structure Determination.• Etc…….
EXAMPLE
• Input Shelx Style: sucrose.res• (Alternatively: .cif,.pdb,.fdat,.spf style)• Invoke PLATON (UNIX: platon sucrose.res)• Opening Menu (4 areas)• Automatic ORTEP style PLOT• Automatic PLUTON style PLOT• Automatic NEWMAN PLOTS• Simulated Powder Pattern• H-Bond Table
EXAMPLE
• Input Shelx Style: sucrose.res• (Alternatively: .cif,.pdb,.dat,.spf style)• Invoke PLATON (UNIX: Platon sucrose.res)• Opening Menu (4 areas)• Automatic ORTEP style PLOT• Automatic PLUTON style PLOT• NEWMAN PLOTS• Simulated Powder Pattern• H-Bond Table
EXAMPLE
• Input Shelx Style: sucrose.res• (Alternatively: .cif,.pdb,.dat,.spf style)• Invoke PLATON (UNIX: Platon sucrose.res)• Opening Menu (4 areas)• Automatic ORTEP style PLOT• Automatic PLUTON style PLOT• NEWMAN Plots• Simulated Powder Pattern• H-Bond Table
EXAMPLE
• Input Shelx Style: sucrose.res• (Alternatively: .cif,.pdb,.dat,.spf style)• Invoke PLATON (UNIX: Platon sucrose.res)• Opening Menu (4 areas)• Automatic ORTEP style PLOT• Automatic PLUTON style PLOT• NEWMAN Plots• Simulated Powder Pattern• H-Bond Table
EXAMPLE
• Input Shelx Style: sucrose.res• (Alternatively: .cif,.pdb,.dat,.spf style)• Invoke PLATON (UNIX: Platon sucrose.res)• Opening Menu (4 areas)• Automatic ORTEP style PLOT• Automatic PLUTON style PLOT• NEWMAN Plots• Simulated Powder Pattern• H-Bond Table
EXAMPLE
• Input Shelx Style: sucrose.res• (Alternatively: .cif,.pdb,.dat,.spf style)• Invoke PLATON (UNIX: Platon sucrose.res)• Opening Menu (4 areas)• Automatic ORTEP style PLOT• Automatic PLUTON style PLOT• NEWMAN Plots• Simulated Powder Pattern• H-Bond Table
CALC ALL GEOMETRY LISTING
• With CALC ALL an exhaustive listing of derived intra-, inter- and coordination geometry etc. is produced.
• Two ‘identical’ files are produced. ‘.lis’ and ‘lps’. The first is lineprinter style, the latter is suitable for either a postscript printer or inspection with ghostview.
• We routinely provide this listing to the client along with an ORTEP.
PLATON/ADDSYM ANALYSIS
• Example run on 9163 Z’ = 2 Organic structures present in the in CSD.
• ADDSYM 466 Hits (Missed or Pseudo Symmetry Cases)
• Some Missed Symmetry Cases already corrected by Dick Marsh et al.
• Recent Example of Missed Symmetry in J.A.C.S (2002) 124,11846-11847
ADDSYM REPORT 2003/1
>
>
(25 out of 466)
J.A.C.S. 124 (2002) 9052
Communications
IUCR CHECKCIF ALERTSData From Supplementary Material
NEWSYM
• Companion to ADDSYM Analysis
• Structure factors calculated from current cell, symmetry and coordinate info.
• Determination of the Space Group from the systematic absences in F(calc)
• Extinctions in F(calc) may differ from those in F(obs) due to poor data.
QUATERNION FIT
• In many cases, an automatic molecule fit can be performed
• A) Identical atom numbering
• B) Sufficient Unique Atoms
• C) Manual picking of a few atom pairs
QUATERNION FIT
Cg1 0.946 0.234 0.592
Cg2 0.441 0.253 0.581
STRUCTURE VALIDATION
Single crystal structure validation addresses three important questions:
1 – Is the reported information complete?
2 – What is the quality of the analysis?
3 – Is the Structure Correct?
IUCR-CHECKCIF
IUCR-TESTS:- MISSING DATA, PROPER PROCEDURE, QUALITY
PLATON TESTS:- SYMMETRY, GEOMETRY, DISPLACEMENT
PARAMETERS
ALERT LEVELS:- ALERT A - SERIOUS PROBLEM- ALERT B - POTENTIALLY SERIOUS PROBLEM- ALERT C - CHECK & EXPLAIN
Problems Addressed by PLATON
- Missed Higher Space Group Symmetry- Solvent Accessible Voids in the Structure- Unusual Displacement Parameters- Hirshfeld Rigid Bond test- Miss-assigned Atom Type - Population/Occupancy Parameters- Mono Coordinated/Bonded Metals- Isolated Atoms
Problems Addressed by PLATON
- Too Many Hydrogen Atoms on an Atom
- Missing Hydrogen Atoms
- Valence & Hybridization
- Short Intra/Inter-Molecular Contacts
- O-H without Acceptor
- Unusual Bond Length/Angle
- CH3 Moiety Geometry
Validation with PLATON
- Details: www.cryst.chem.uu.nl/platon- Driven by the file CHECK.DEF with criteria,
ALERT messages and advice.- Button VALIDATION on PLATON MAIN Menu- Use: platon –u structure.cif- Result on file: structure.chk- Applicable on CIF’s and CCDC-FDAT- FCF-Valid: platon –V structure.cif
Example of Misplaced Hydrogen Atom
Two ALERTS related to the misplaced Hydrogen Atom
Unsatisfactory Hydrogen Bond Network
Satisfactory Hydrogen Bond Network with new H-position
ARU-Definition
• Molecules (or unique asymmetric parts of a molecule) are assigned in PLATON an ARU value.
• npqr.s where n = symmetry number and
pqr translations and s the residue #
e.g. 2655.02
Used to address symmetry related molecules in packing diagrams and intermolecular contacts.
Solvent Accessible Voids
• A typical crystal structure has only 65% of the available space filled.
• The remainder volume is in voids in-between atoms (to small to accommodate an H-atom)
• Solvent accessible voids defined are regions in the structure that can accommodate at least a sphere with radius 1.2 Angstrom without intersecting with any of the van der Waals spheres assigned to each atom in the structure.
STEP #1 – EXCLUDE VOLUME INSIDE THE VAN DER WAALS SPHERE
DEFINE SOLVENT ACCESSIBLE VOID
DEFINE SOLVENT ACCESSIBLE VOID
STEP # 2 – EXCLUDE AN ACCESS RADIAL VOLUMETO FIND THE LOCATION OF ATOMS WITH THEIR
CENTRE AT LEAST 1.2 ANGSTROM AWAY
DEFINE SOLVENT ACCESSIBLE VOID
STEP # 3 – EXTEND INNER VOLUME WITH POINTS WITHIN1.2 ANGSTROM FROM ITS OUTER BOUNDS
SQUEEZE
• Takes the contribution of disordered solvents into account by back-Fourier transformation of density found in the ‘solvent accessible volume’ outside the ordered part of the structure.
• Filter: Input shelxl.res & shelxl.hkl
Output: ‘solvent free’ shelxl.hkl
SQUEEZE PROCEDURE
• Refine structure including H-atoms• Use .res and .hkl for the SQUEEZE calculation• Continue refinement using the reflection file
produced by SQUEEZE• Calculate a final .fcf using the latest .res and .hkl
(from SQUEEZE) using PLATON/FCF• Append the .fsq file to the final .cif for
publication.
Twinning
• Twinning results in overlap of reflections with different hkl
• Twinning can be detected during the data collection experiment
• Cases of (Pseudo) Merohedral twinning are generally detected during the structure determination
TWINNING - SYMPTOMS
• Spots that do not fit in the proposed lattice• Strange extinctions• Laue symmetry higher than consistent with the
systematic extinctions.• E-statistics• Unexpected high R-value• Ghost peaks in the difference map• A Significant # of reflections with Fobs >> Fcalc
TWIN DETECTION
• SOFTWARE: ROTAX & PLATON/TWINROTMAT
• ANALYSIS BASED ON (CIF &) FCF FILES
• PROPOSALS FOR TWIN-OPERATION
SYSTEM S
• Guided or Automatic Crystallographic Shell for Structure Determination from diffraction data to refined structure.
• INPUT: HKL, CELL & CONTENT data• Interface to SHELX(S/L), DIRDIF,SIR97,
SIR2002, POVRAY,RASTER3D etc.• Internal: PLATON Tools: Space Group Det,
Abs.Cor., Graphics, ADDSYM etc.
Input for an Exec of System S
• System S is available for LINUX only• KappaCCD/DENZO: platon –s import.cif• Comp.hkl + comp.ins (= title,cell,sfac,unit,hklf 4)
platon –s comp.ins• Comp.cif + comp.fcf (Acta): platon –s comp.cif• Default: suggestions for next step (can be
overruled by the user)• Automatic Mode: add ‘nqa’:
platon –s comp.ins nqa
Finally
• Other features:
• Renaming of atoms, cif2res, asym-view
• More Info:
• ‘www.cryst.chem.uu.nl/platon’
• Right mouse clicks > help on menu item
• DEMO