Suppression of isotopic polymorphism. Issue 4 (6th January 2021)

• Record Type: Journal Article
• Authors: Funnell, Nicholas P.; Allan, David R.; Maloney, Andrew G. P.; Smith, Ronald I.; Wilson, Cameron J. G.; Parsons, Simon
• Is Part Of: CrystEngComm. Volume 23:Issue 4(2021)
• Page Start: 769
• Page End: 776
• Publication Date: 2021-01-06
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/d0ce01636e
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : Crystallisation at pressure overcomes the effect of isotopic polymorphism in the methylpyridine pentachlorophenol co-crystal. Though the hydrogenated Cc polymorph can only be obtained at pressure, it is stable on recovery to ambient conditions. Abstract : The 4-methylpyridine pentachlorophenol co-crystal is known to exhibit the unusual phenomenon of isotopic polymorphism—the hydrogenated form crystallises with triclinic symmetry whereas deuteration of the phenol leads to growth of a monoclinic form instead. We report the use of pressure to overcome the zero point energy difference that leads to the two forms, instead engineering the formation of a hydrogenated, monoclinic co-crystal. This form cannot be obtained via direct compression of the triclinic form, but can be recovered from a diamond anvil cell following pressure-induced growth from solution. Furthermore, with Density Functional Theory calculations, we outline the conditions under which the remaining triclinic–deuterated form might be obtained.