Enantiotropic conformational polymorphism in 2,2,4,4-bis-(2′,2′-dimethylpropane-1′,3′-dioxy)-6,6-dichlorocyclotriphosphazene
Hacıvelioğlu, F. and Montis, R. and Davies, David B. and Kiliç, A. and Hursthouse, Michael B. and Coles, Simon J. (2011) Enantiotropic conformational polymorphism in 2,2,4,4-bis-(2′,2′-dimethylpropane-1′,3′-dioxy)-6,6-dichlorocyclotriphosphazene. CrystEngComm 13 (12), pp. 4102-4109. ISSN 1466-8033.
Conformational polymorphism has previously been observed in 2,2-dichloro-4,4:6,6-bis(2,2′-dimethlypropane-1,3-dioxy)-cyclotriphosphazene and the crystal structures of two forms were reported. In that study the melting points of both forms (α and β) were reported as 211–212 °C and no investigation was made on the stability of, or the thermodynamic relationships between the polymorphs. In the present work the two forms were characterized by various analytical techniques, such as single-crystal X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomicroscopy (TM) and variable temperature single crystal and powder X-ray diffraction. Thermal analysis suggests that the polymorphs are enantiotropically related and it is found that the solid–solid transformation of the β to α form may start with defects of α form inside the β form followed by a nucleation and growth type mechanism involving at least three main molecular centred events; conformational change, rotation and tilting.
|School:||Birkbeck Schools and Departments > School of Science > Biological Sciences|
|Date Deposited:||17 Aug 2011 08:04|
|Last Modified:||17 Apr 2013 12:21|
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