vortrag, erice, 2004 polymorphism and pigments ii martin u. schmidt, frankfurt am main presentation...
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Vortrag, Erice, 2004
Polymorphism and Pigments II
Martin U. Schmidt, Frankfurt am Main
Presentation given in Erice, 2004
Quinacridone (Pigment Violet 19)
N
N
O
HO
H
diluted solution
N
N
O
HO
H
phase phase
Isolated molecule Crystal
phase
used for laquers, paints...
Colour of quinacridone
N
N
O
HO
H
N
N
O
HO
H
N
N
O
HO
H
MoleculeCrystal
N
N
O
HO
H
Weak conjugation between benzene rings
=> yellow
N
N
O
HO
H
H
ON
N
O
H
Colour shift from yellow to red because of:
1) Enhanced conjugation in the molecule=> Smaller HOMO-LUMO distances => Absorption bands shift from blue to green => Resulting colour shifts from yellow to red
2) Interaction of transition dipole moments (excitons)
Crystal structures of and quinacridone
phase phase
[E.F. Paulus et al., ECM-12, Moskow, 1989]
Polymorphism and crystal engineering
Polymorphism
Problems
"Polymorphism problem"
Using the advantages
"Crystal Engineering"
Properties depending on the polymorphic form
Selection of polymorphic form (and properties) using solid solutions
-Phase -Phase
NH
O
O
NH
H
H
NH
O
O
NH
Cl
NH
O
O
NH
H
O
NH
N
O
O
N
H
H
O
N
H
N
O
O
NH
H
N
O
O
N
Cl
H
H
Selection of polymorphic form (and properties) using solid solutions
-Phase -Phase
NH
O
O
NH
H
H
NH
O
O
NH
Cl
NH
O
O
NH
H
O
NH
N
O
O
N
H
H
O
N
H
N
O
O
NH
H
N
O
O
N
Cl
H
H
Cl
Cl
Selection of polymorphic form (and properties) using solid solutions
Pigment Red 207
(commercial)
Cl
Cl
Polymorphs of Pigment Orange 36
phase phase
N
Cl N
O
O
H
N
O
O
N
H
NH
NH
O
Pigment Orange 36 (Azo pigment)
Novoperm® Orange HL
SynthesisSolvent
(no use)
solvents
150°C, 2h
Polymorphs of Pigment Orange 72
with stirring
without stirring
phase(stable, but no use)
phase(stable, commercial)
phase(metastable)
Synthesis in water
N
H
N
O
CH3
O
N
H
N
N
O
H
H
N
N
H
CH3
O
N
O
ClCl
H
N
N
H
H
OPigment Orange 72
(a diaryl azo pigment)
How many polymorphic forms are known?
Number of known polymorphic forms
un
kno
wn
Nu
mb
er
of
pig
me
nts
Pigment Red 53
M2+
M2+ = Ca2+, Sr2+, Ba2+
Synthesis of Pigment Red 53:2
NNH
O
Cl
SO3
CH3
-
Ca2+
2
NH2
Cl
CH3
SO3HNaNO2
+ 2 HCl N+
N
Cl
CH3
SO3H
Cl-
NN
OH
Cl
SO3Na
CH3
+
OH
+ NaOH
+ CaCl2N
NH
O
Cl
SO3Na
CH3
+
Polymorphism of Pigment Red 53
Ba2+ salt, "Pigment Red 53:1"
- phase: bright red. Produced industrially (>> 10 000 tons / year) Used for printing inks (and plastics)
- phase: orange-red No longer commercially produced
Sr2+ salt, "Pigment Red 53:3"
- 6 polymorphic forms, orange - red
- Limited commercial use.
Compound invented 1902 [Deutsches Reichspatent Nr. 145908]
Ca2+ salt, "Pigment Red 53:2"
- Only 1 polymorphic form known until 1997. Then we started searching ...
Polymorphism of Pigment Red 53:2+ CaCl2
iso-butanole
(+ + Na salt)
(+ )
chlorobenzene
recryst. from DMAc / H2O
ethanole
1-butanole
aceto-phenone
(+)
(+)
DMSO
acetone
synthesis from K+ salt
glycole
glycolic acid butylester
NMF / H2O
Na+ salt
morpholene
DMSO
NMF / H2O
*
*
*
*
* Solvent containing
DMF
recryst. from
(Slurry)
M.U. Schmidt, H.J. Metz, EP 965616 (1999)M.U. Schmidt, H.J. Metz, EP 965617 (1999)M.U. Schmidt, EP 1010732 (1999)
(Na+ salt)
(K+ salt)
More than 200 experiments made
• 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
1-butanole
isobutanole / H2O
+ 2-ethylhexanole
=> Which is the thernodynamically stable phase at 100°C ??
Polymorphism of Pigment Red 53:2
Polymorphism of Pigment Red 53:2Practical Problems
• Most experiments give mixtures of phases.
• Some phases cannot be obtained in pure form (, , , )
• Several experiments could not be reproduced. E.g.
Exp. No. 99)Dissolution in
dimethylacetamide / H2OPrecipitation with H2O
Exp. No. 148)
Powder diagrams:
• Generally only 10-20 peaks.
• No diagram could be indexed reliably => electron diffraction (Ute Kolb)
Polymorphism of Pigment Red 53:2Practical Problems
• The synthesis is incomplete:
+ CaCl2Na+ salt(slurry)
Ca2+ salt(slurry)H2O, 90°C, 2h
=> Contamination with the Na+ salt
• Na+ content ? (AAS). => Admixture or solid solution Na+ / Ca2+?
• H2O content ? (Karl-Fischer titration). E.g. phase: 2H2O
• Solvent content ? (NMR) E.g. 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 ??
Na+ salt(slurry)
+
Many questions still open.
Diaryl pigments
N
N
CH3
O
N
O
Cl
CH3 N
N
O
CH3
O
N
Cl
CH3
H
H
H
H
R
R
R1
R2
R1
R2
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
Important yellow pigments
Sales > 200 Mio Euro per year
Pigment Yellow 14: Structure solution by lattice energy minimization using CRYSCA
10 15 20 25 30 35 2 / °
ExperimentalX-ray powder
diagram(Lab data)
50 000
40 000
30 000
20 000
10 000
0
Intensity / Counts
Lattice energy minimizations
(prediction of possible crystal structures)
by CRYSCA
Indexing• Unit cell• Possible space groups (P 1 or P 1, Z = 1)–
60 000
Pigment Yellow 14: Molecular geometry
N
N
CH3
O
N
O
Cl
CH3 N
N
O
CH3
O
N
Cl
CH3
H
H
H
H
R
R
5 intramolecular degrees of freedom
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
Martin U. Schmidt, Ulli Englert: "Prediction of Crystal Structures", J. Chem. Soc., Dalton Trans. 1996, 2077-82.
• All space groups possible (even disorders etc.)
• User-selected intramolecular degrees of freedom (from the beginning)
• Lattice parameters either given or calculated by CRYSCA
CRYSCA: Prediction of possible crystal structures
Pigment Yellow 14: Structure solution by lattice energy minimization using CRYSCA
10 15 20 25 30 35 2 / °
ExperimentalX-ray powder
diagram(Lab data)
50 000
40 000
30 000
20 000
10 000
0
Intensity / Counts
Lattice energy minimizations
by CRYSCA (in P 1)• a, b, c, , , , fixed• Packing and 5 intramol. torsions optimized
Indexing• Unit cell• Possible space groups (P 1 or P 1, Z = 1)–
60 000
Pigment Yellow 14: Structure solution by lattice energy minimization using CRYSCA
10 15 20 25 30 35 2 / °
ExperimentalX-ray powder
diagram(Lab data)
Calculated Best minimum (P 1)
50 000
40 000
30 000
20 000
10 000
0
Intensity / Counts
Calculation of X-ray powder diagram
–
Indexing• Unit cell• Possible space groups (P 1 or P 1, Z = 1)–
60 000
Lattice energy minimizations
by CRYSCA (in P 1)• a, b, c, , , , fixed• Packing and 5 intramol. torsions optimized
Pigment Yellow 14: Synchrotron data and Rietveld refinement
Inte
nsi
tät
(Co
un
ts)
Dif
f.
experimentalcalculated
Rp = 8.53 %, Rwp = 12.87 %, RF2 =17.60%, 2 = 3.3
NSLS Brookhaven = 1.149 Å
Pigment Yellow 14
(R1 = CH3, R2 = H)
Pigment Yellow 12
(R1 = R2 = H)
Herringbone structure
Pigment Yellow 13
(R1 = R2 = CH3)
Pigment Yellow 12 / 13 / 14: Crystal structures
• Violet Pigment, high colour strength
• Insoluble in all solvents, even in: - DMSO or NMP at 200°C (detection limit about 10 g/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!
Polymorphism: A really hard case
O
N
N
O
Cl
Cl
NH
NNH
NOO
CH3
CH3
Methyl-dioxazine
phase phase
Salt kneading with solvents
"dilution" withconc. CH3COOH
1) + dichlorobenzene
2) evaporation
phase phase
phase
Synthesis in conc. H2SO4/MnO2
NMP18h 200°
Methyl-dioxazine: Polymorphic forms
evaporation
phase
[P. Kempter, M.U. Schmidt, R. Born, European Patent, 2002]
CF3COOH
Protonated form
O
N
N
O
Cl
Cl
NH
NNH
NOO
CH3
CH3
• FWHM about 0.5° in 2• Crystallite size about 20 nm • Indexing not possible-Phase (metastabile)
Measuring conditions:• STOE STADI-P• capillary• transmission• primary Ge [111] monochromator • Cu-K1
• linear PSD
Crystal structure determination from a non-indexable powder diagram
O
N
N
O
Cl
Cl
NH
NNH
NOO
CH3
CH3
Can the crystal structure be determined from such a X-ray powder diagram?
Only method:
Lattice energy minimizations, using the molecular geometry
Methyl-dioxazine: Structure solution
P 1Z = 2
P 21
Z = 2P 21/cZ = 4
C 2/cZ = 8
P 212121
Z = 4P 1
Z = 1P 21/cZ = 2
P b c aZ = 4
––
5 10 15 20 25 30 2 / °
Lattice energy minimizations (CRYSCA)
Calculated possible crystal structures
Calculation of powder diagrams
Calculated structure(energy rank no. 5)
Intensity
Experimental X-ray powder diagram
(P 1, Z = 1)–
...
Methyl-dioxazine: Crystal structure
Cl
N
O
Density: = 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.
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
Acknowledgements
and all the others
...