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Alkali Metal Salts of 10,12-Pentacosadiynoic Acid and Their Dosimetry Applications

Hall, Amy V. and Musa, Osama M. and Hood, David K. and Apperley, David C. and Yufit, Dmitry S. and Steed, Jonathan W. (2021) 'Alkali Metal Salts of 10,12-Pentacosadiynoic Acid and Their Dosimetry Applications.', Crystal growth & design., 21 (4). pp. 2416-2422.


Wide-dose-range 2D radiochromic films for radiotherapy, such as GAFchromic EBT, are based on the lithium salt of 10,12-pentacosadiynoic acid (Li-PCDA) as the photosensitive component. We show that there are two solid forms of Li-PCDA—a monohydrated form A and an anhydrous form B. The form used in commercial GAFchromic films is form A due to its short needle-shaped crystals, which provide favorable coating properties. Form B provides an enhanced photoresponse compared to that of form A, but adopts a long needle crystal morphology, which is difficult to process. The two forms were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, CP-MAS 13C solid-state NMR spectroscopy, and thermogravimetric analysis. In sum, these data suggest a chelating bridging bidentate coordination mode for the lithium ions. The sodium salt of PCDA (Na-PCDA) is also reported, which is an ionic cocrystal with a formula of Na+PCDA–·3PCDA. The PCDA and PCDA– ligands display monodentate and bridging bidentate coordination to the sodium ion in contrast to the coordination sphere of the Li-PCDA forms. In contrast to its lithium analogues, Na-PCDA is photostable.

Item Type:Article
Full text:(AM) Accepted Manuscript
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Publisher statement:This document is the Accepted Manuscript version of a Published Work that appeared in final form in Crystal Growth and Design, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see
Date accepted:No date available
Date deposited:27 October 2021
Date of first online publication:25 March 2021
Date first made open access:25 March 2022

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