Polymorphism in an oligo(aryl ether ketone)

✍ Scribed by Daniel R. Rueda; Mikhail G. Zolotukhin; Isabel André; Martin Martinez Ripoll; Javier de Abajo; Julio C. Alvarez

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 919 KB
• Volume: 198
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1997.021980707

✦ Synopsis

Abstract

1,3‐Bis(4‐phenoxybenzoyl)benzene (1) shows a single melting peak at T~1~ = 120°C when rapidly crystallized from a methanol/benzene mixture (10:1 v/v) (sample A) and a double melting peak at T~1~ = 120°C and T~2~ = 130°C when crystallized slowly (overnight) (sample B). Slow recrystallization of 1 using ethanol instead of methanol induces the formation of large single crystals which only show a single melting peak at T~2~ = 130°C (sample C). Analysis of powder X‐ray diffractograms obtained for A, B and C samples clearly point out the coexistence of two crystalline phases in sample B: phase 1 (observed for sample A) and phase 2 (sample C). From optical microscopy and thermal (DSC) observations, it can be concluded that, upon heating, phase 1 melts at T~1~ and the molten material converts itself into phase 2 if some crystals of phase 2 are present. Single crystal structure determination of, both, phase 1 and 2 reveal conformational differences of the molecule in both phases which pack in an orthorhombic and a monoclinic unit cell, respectively.