Polymorphs Influence of stirring

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Polymorphs Influence of stirring Powered By Docstoc
					Polymorphism and Pigments II

Martin U. Schmidt, Frankfurt am Main

Presentation given in Erice, 2004




                       Vortrag, Erice, 2004
        Quinacridone (Pigment Violet 19)
    H         O                H         O
    N                          N


              N                          N
    O         H                O         H

Isolated molecule                  Crystal




  diluted solution   a phase   b phase         g phase

                               used for laquers, paints...
                   Colour of quinacridone
                                                                       H
      H        O                H         O                            O
      N                         N                            N


               N                          N                            N
      O        H                O         H                  O
                                                                       H
                                          O                  H
                                H                                      O
      H        O                N                            N
      N
                                          N                            N
               N                O         H                  O
      O        H                                             H
                                                Crystal
       Molecule
                        Colour shift from yellow to red because of:
Weak conjugation        1) Enhanced conjugation in the molecule
between benzene rings       => Smaller HOMO-LUMO distances
=> yellow                      => Absorption bands shift from blue to green
                                  => Resulting colour shifts from yellow to red
                        2) Interaction of transition dipole moments (excitons)
Crystal structures of b and g quinacridone




       b phase                                           g phase
                 [E.F. Paulus et al., ECM-12, Moskow, 1989]
Polymorphism and crystal engineering


                    Polymorphism



     Properties depending on the polymorphic form



       Problems                 Using the advantages



 "Polymorphism problem"         "Crystal Engineering"
   Selection of polymorphic form
(and properties) using solid solutions
                          H       O
              O
    H                     N
    N

                                  N
              N
              H           O       H
    O             H
              O   H       H       O
    H                         H
    N                     N   N


              N                   N
              H
    O             H       O   O   H
              O   Cl                    Cl
    H                     H       O
    N                     N

              N                   N
              H
    O                     O       H


    b-Phase                   g-Phase
   Selection of polymorphic form
(and properties) using solid solutions
                             H       O
              O
    H                        N
    N

                                     N
              N
              H              O       H
    O             H
              O   H          H       O
    H                            H
    N                        N   N


              N                      N
              H
    O             H          O   O   H
              O   Cl    Cl                 Cl
    H                        H       O
    N                        N

              N                      N
              H
    O                        O       H     Cl


    b-Phase                      g-Phase
   Selection of polymorphic form
                    N
              O     H
(and properties) using solid solutions
              H     O
                      H
                  N   N


                          N
                  O   O   H
            Cl    H       O     Cl
                  N


                          N
                  O       H     Cl




             Pigment Red 207
                 (commercial)
       Polymorphs of Pigment Orange 36
                     O
                         H
                                 H
                         N       N
             N
                                        O
             N       O           N
                 H               H
                 O
     Cl      N               Pigment Orange 36
             O                 (Azo pigment)


                             Solvent
Synthesis    a phase                        b phase

              (no use)                 Novoperm® Orange HL
    Polymorphs of Pigment Orange 72
                         CH3                                  CH3
                     O                                              O
                 H         N                              N             H
                     N         N                      N             N
                         O H                              H O
     H                                                                               H
         N                         Cl            Cl                              N

     O       N                                                               N       O
             H
                                    Pigment Orange 72                       H
                                   (a diaryl azo pigment)

Synthesis in water
                                                       with                      g phase
                                                      stirring              (stable, but no use)
                           solvents
   a phase
   (metastable)            150°C, 2h

                                                      without
                                                                                 b phase
                                                      stirring              (stable, commercial)
How many polymorphic forms are known?
                         Anzahl der bekannten Kristallmodifikationen

                          70
                                                                         62
                          60
   Number of Pigmente
   Anzahl der pigments


                          50
                          40
                          30
                          20
                          10        9   8
                                6           5
                                                1   1    1         1
                           0
                               1

                                    2

                                        3

                                            4

                                                5

                                                    6



                                                        10



                                                               15



                                                                       unbekannt
                                                                        unknown
                               NumberAnzahl der Modifikationen
                                      of known polymorphic forms
Pigment Red 53

           Cl
  CH3
                    O
                        O
                    S
           N        O
       N        H
                                  2+
                O               M2+
                                Ca



                            2
 M2+ = Ca2+, Sr2+, Ba2+
           Synthesis of Pigment Red 53:2
      Cl                                                     Cl
                                                                                             Cl
H3C                                             H3C                                 CH3
                               + NaNO2                                                                O
            SO3H                                                                                          O
                                                                    SO3H                              S
                               + 2 HCl                        +
      NH2                                                    N                               N        O
                                                                                         N        H
                                                                  Cl-                                                   2+
                                                             N                                    O                Ca

                                           OH
                      +                                                                                       2


                          + NaOH


                     Cl                            Cl                                     Cl
           H3C                           H3C                                  H3C

                           SO3Na                            SO3Na                                    -
                                                                                                   SO3
                     N                             NH                                     NH
                 N                             N                    + CaCl2          N                        2+
                                                                                                          Ca
                          OH                            O                                      O
                                                                                                            2
        Polymorphism of Pigment Red 53
Compound invented 1902 [Deutsches Reichspatent Nr. 145908]

                     Ba2+ salt, "Pigment Red 53:1"
- a phase: bright red.
           Produced industrially (>> 10 000 tons / year)
           Used for printing inks (and plastics)
- b phase: orange-red
           No longer commercially produced


                      Sr2+ salt, "Pigment Red 53:3"
- 6 polymorphic forms, orange - red
- Limited commercial use.

                     Ca2+ salt, "Pigment Red 53:2"
- Only 1 polymorphic form known until 1997. Then we started searching ...
                 Polymorphism of Pigment Red 53:2
                                  + CaCl2              DMSO
      Na+ salt                                                           p          *
                                            DMSO       morpholene
                      b (Na+ salt)                                              i               *
                                 iso-butanole                recryst. from
                  g                                          NMF / H2O              k (+q)
                           chlorobenzene                      acetone
             d                                                                          l (+a)
                          recryst. from                           synthesis
         e                DMAc / H2O               a             from K+ salt           m (K+ salt)
                               ethanole                          glycole
             z                                                                              n             *
                                     1-butanole           glycolic acid
          h (+ z + Na salt)                                butylester                   x             *
                                       aceto-            NMF / H2O
                       q (+ z)        phenone                 (Slurry)          o
                                                       DMF
M.U. Schmidt, H.J. Metz, EP 965616 (1999)          r                         * Solvent containing
M.U. Schmidt, H.J. Metz, EP 965617 (1999)
M.U. Schmidt, EP 1010732 (1999)                    More than 200 experiments made
      Polymorphism of Pigment Red 53:2
• All 15 phases are concomitant.
• All phases are stable from room temperatur to at least 250-300°C.
• Some phases transform on heating to 250-300°C.
• All reactions are kinetically controlled.
    e.g. Slurry conversion experiments at about 100°C:

                chlorobenzene / H2O
                                              d
                  isobutanole / H2O                    1-butanole
          a                                   g                     h+z
                                                  2-ethylhexanole
                                                                    z+q

     => Which is the thernodynamically stable phase at 100°C ??
      Polymorphism of Pigment Red 53:2
             Practical Problems
Powder diagrams:
• Generally only 10-20 peaks.
• No diagram could be indexed reliably
  => electron diffraction (Ute Kolb)


• Most experiments give mixtures of phases.
• Some phases cannot be obtained in pure form (k, l, h, q)
• Several experiments could not be reproduced. E.g.

                                                        e    (Exp. No. 99)
            Dissolution in            Precipitation
     a
            dimethylacetamide / H2O   with H2O
                                                       a+q   (Exp. No. 148)
      Polymorphism of Pigment Red 53:2
             Practical Problems

• The synthesis is incomplete:

         Na+ salt        + CaCl2          Ca2+ salt            Na+ salt
                                                       +
         (slurry)     H2O, 90°C, 2h       (slurry)             (slurry)

 => Contamination with the Na+ salt
• Na+ content ? (AAS).
     => Admixture or solid solution Na+ / Ca2+?
• H2O content ? (Karl-Fischer titration). E.g. g phase: 2H2O
• Solvent content ? (NMR)
    E.g. x phase: pigment / solvent (glycolic acid butyl ester) = 1 / 7
        => Solvent probably not in the crystal lattice, but on the surface
            But how to remove the solvent ??
Many questions still open.
                            Diaryl pigments
          R2
          R
                                                                H3C
                                     Cl                                 O
                         O H                                    N           H
          C
        H3R1         N           N                          N           N       CH
                                                                                R1 3
                 H           N                                  H O
                     O                                 Cl
                         CH3
                                      Important yellow pigments                  R
                                                                                 R2
                                      Sales > 200 Mio Euro per year

R1 = R2 = H:             Pigment Yellow 12          3 polymorphs
R1 = R2 = CH3:           Pigment Yellow 13          1 polymorph       (... as far as I know)
R1 = CH3, R2 = H:        Pigment Yellow 14          1 polymorph       (... as far as I know)
       No single crystals => Structure solved from X-ray powder data
         Pigment Yellow 14: Structure solution by
        lattice energy minimization using CRYSCA
Intensity / Counts                                               Indexing
                                                       • Unit cell
60000
                                                       • Possible space groups
50000                                                              –
                                    Experimental         (P 1 or P 1, Z = 1)
40000                               X-ray powder
30000                                  diagram
                                     (Lab data)             Lattice energy
20000
                                                            minimizations
10000
                                                        (prediction of possible
    0
                                                          crystal structures)
              10     15   20   25   30   35   2q / °
                                                             by CRYSCA
Pigment Yellow 14: Molecular geometry


  R
                                              H3C
                         Cl                         O
              O H                             N         H
H3C       N          N                    N         N       CH3
      H          N                            H O
          O                          Cl
              CH3
                                                            R

              5 intramolecular degrees of freedom
CRYSCA: Prediction of possible crystal structures

                                                                              
                                    A  r 6 + B  e Crij + 1  qi  q j
                          
                      1                                                        +E
                E   
                      2                   ij
                                                               4pee 0 rij         intramol   .
                          i   j                                               

           A, B, C:       Force field parameters (C,H,B,N,O,F,Cl,Si,metals)
           q:             Atomic point charges
           Eintramol.:    Intramolecular energy, depending on the degrees of freedom,
                          e.g. for                       : 6-term cosine serie,
                                                           fitted to ab initio calculations


         • All space groups possible (even disorders etc.)
         • User-selected intramolecular degrees of freedom
           (from the beginning)
         • Lattice parameters either given or calculated by CRYSCA
 Martin U. Schmidt, Ulli Englert: "Prediction of Crystal Structures", J. Chem. Soc., Dalton Trans. 1996, 2077-82.
         Pigment Yellow 14: Structure solution by
        lattice energy minimization using CRYSCA
Intensity / Counts                                               Indexing
                                                       • Unit cell
60000
                                                       • Possible space groups
50000                                                              –
                                    Experimental         (P 1 or P 1, Z = 1)
40000                               X-ray powder
30000                                  diagram
                                     (Lab data)               Lattice energy
20000
                                                              minimizations
10000                                                      by CRYSCA (in P 1)
    0                                                  • a, b, c, a, b, g, fixed
              10     15   20   25   30   35   2q / °   • Packing and 5 intramol.
                                                         torsions optimized
         Pigment Yellow 14: Structure solution by
        lattice energy minimization using CRYSCA
Intensity / Counts                                                   Indexing
                                                           • Unit cell
60000
                                                           • Possible space groups
50000                                                                  –
                                    Experimental             (P 1 or P 1, Z = 1)
40000                               X-ray powder
30000                                  diagram
                                     (Lab data)                   Lattice energy
20000
                                                                  minimizations
10000                                                          by CRYSCA (in P 1)
    0                                                      • a, b, c, a, b, g, fixed
                                                           • Packing and 5 intramol.
                                                             torsions optimized


                                                                             –
                                         Calculated          Best minimum (P 1)


                                                             Calculation of X-ray
              10     15   20   25   30       35   2q / °      powder diagram
          Pigment Yellow 14:
Synchrotron data and Rietveld refinement
                                                            experimental
                                                            calculated
  Intensität (Counts)




                                                       NSLS Brookhaven
                                                       l = 1.149 Å
    Diff.




                        Rp = 8.53 %, Rwp = 12.87 %, RF2 =17.60%, c2 = 3.3
Pigment Yellow 12 / 13 / 14: Crystal structures

                                  Pigment Yellow 14
                                  (R1 = CH3, R2 = H)

                                  Pigment Yellow 13
                                  (R1 = R2 = CH3)




                                  Pigment Yellow 12
                                  (R1 = R2 = H)
                                  Herringbone structure
           Polymorphism: A really hard case
                                           Cl              CH3
                             H       N          O
                             N                             N
                       O                                         O
                             N       O          N          N
                                                           H
                           H3C             Cl
                                    Methyl-dioxazine
• Violet Pigment, high colour strength
• Insoluble in all solvents, even in:
  - DMSO or NMP at 200°C (detection limit about 10 mg/l)
  - molten benzoic acid (about 200°C)
  - phthalic acid esters at 300°C
• Melting point > 400 °C (decomposition)
• Sublimation at 350°C, 10-3 mbar
  leads to poor crystallinity
• Bad powder diagrams
• No single crystals
• Nevertheless: 6 polymorphic forms!
    Methyl-dioxazine: Polymorphic forms
                Synthesis in conc. H2SO4/MnO2


    NMP                          Cl             CH3
                      H
    18h 200°          N      N          O       N
                O                                     O   Salt kneading
                      N                         N
                                                          with solvents           h phase
a phase
                             O          N       H
                    H3C          Cl
                             d phase

                                      CF3COOH                 1) + dichlorobenzene
    "dilution" with
    conc. CH3COOH                                             2) evaporation
                          Protonated form

                                      evaporation
b phase                                                                   e phase
                             z phase
                                                            [P. Kempter, M.U. Schmidt, R. Born,
                                                            European Patent, 2002]
   Crystal structure determination from
    a non-indexable powder diagram
Can the crystal structure be determined
 from such a X-ray powder diagram?              • FWHM about 0.5° in 2q
                                                • Crystallite size about 20 nm
             b-Phase (metastabile)              • Indexing not possible

                                                 Measuring conditions:
                                                 • STOE STADI-P
                                                 • capillary
                                                 • transmission
                                                 • primary Ge [111] monochromator
                                                 • Cu-Ka1
                                                 • linear PSD
                    Cl               CH3
         H      N        O
         N                           N
                                                        Only method:
   O                                       O
         N      O        N           N         Lattice energy minimizations,
                                     H
       H3C          Cl                         using the molecular geometry
    Methyl-dioxazine: Structure solution
  –                                                             –
P1          P 21          P 21/c    C 2/c    P 212121         P1         P 21/c    Pbca
                                                        ...
Z=2         Z=2           Z=4       Z=8       Z=4             Z=1        Z=2       Z=4

                        Lattice energy minimizations (CRYSCA)

                        Calculated possible crystal structures

                            Calculation of powder diagrams

Intensity


                                                                   Experimental X-ray
                                                                    powder diagram


                                                                   Calculated structure
                                                                   (energy rank no. 5)
                                                                               –
                                                                            (P 1, Z = 1)
      5            10          15       20        25          30        2q / °
Methyl-dioxazine: Crystal structure




                                Cl
                    O
                        N




          Density: r = 1.71 g/cm3
      Some remarks on the method
Crystal structures of organic and organometallic
compounds may be solved from X-ray powder data
by lattice energy minimizations
• even if the powder data are of low quality
• and even if indexing fails.

Limitations:
• Compounds of unknown composition
• Amorphous compounds
• Less than 10-15 peaks in the X-ray powder diagram
• Unexpected crystal symmetries (if indexing fails)
• Unsuitable or missing force field parameters

           Warning: It's not a black box method.
                     Acknowledgements
Coworkers (Hoechst / Clariant GmbH):
• Dr. H. Kalkhof, F. Becker, T. Simon, H.-J. Remsperger

Coworkers (Frankfurt University):
• J. Djanhan, Dr. L. Fink, E. Alig, Dr. D.W.M. Hofmann, C. Buchsbaum

X-ray powder diagrams:
• Prof. E. F. Paulus, U. Conrad (former Hoechst AG)
• Dr. M. Ermrich (X-ray lab, Reinheim)

Synchrotron measurements:
• Prof. P.W. Stephens (NSLS Brookhaven)

Rietveld refinements:
• Dr. R. E. Dinnebier (MPI Solid State Research, Stuttgart)

Electron diffraction:
• Dr. U. Kolb, Univ. Mainz

Financial support:
Acknowledgements
Acknowledgements
  and all
the others
    ...

				
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