Crystal Engineering on Organic Pigments
Crystal Engineering on Organic Pigments
Crystal Engineering on Organic Pigments
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Example 4: Diaryl <strong>Pigments</strong><br />
CH 3<br />
O<br />
Cl<br />
H N<br />
H O<br />
R2 N N<br />
N N R2<br />
O H<br />
Cl �<br />
N<br />
H C 3<br />
H<br />
O<br />
R4 R5<br />
QM calculati<strong>on</strong>s (single molecules):<br />
R = H / CH 3: no influence <strong>on</strong> �<br />
Hypothesis:<br />
�� = 0°: good c<strong>on</strong>jugati<strong>on</strong> of � systems => high �<br />
�� = 40°: hindered c<strong>on</strong>jugati<strong>on</strong> => low �<br />
R5<br />
R4<br />
Are the colour strengths differences<br />
caused by the crystal structures?<br />
=> Structure determinati<strong>on</strong> from powder data<br />
CSD:<br />
� 50 %<br />
� 50 %
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