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Updated: Apr 11, 2026

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Disappearing polymorphs revisited
Dejan-Krešimir Bučar1, Robert W Lancaster2, Joel Bernstein3,4,5
1Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom). d.bucar@ucl.ac.uk.
Abstract:
Nearly twenty years ago, Dunitz and Bernstein described a selection of intriguing cases of polymorphs that disappear. The inability to obtain a crystal form that has previously been prepared is indeed a frustrating and potentially serious problem for solid-state scientists. This Review discusses recent occurrences and examples of disappearing polymorphs (as well as the emergence of elusive crystal forms) to demonstrate the enduring relevance of this troublesome, but always captivating, phenomenon in solid-state research. A number of these instances have been central issues in patent litigations. This Review, therefore, also highlights the complex relationship between crystal chemistry and the law.
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