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The crystal engineering of radiation-sensitive diacetylene cocrystals and salts

DOI: 10.1039/D0SC02540B DOI Help

Authors: Amy V. Hall (Durham University) , Dmitry S. Yufit (Durham University) , David C. Apperley (Durham University) , Larry Senak (Ashland LLC) , Osama M. Musa (Ashland LLC) , David K. Hood (Ashland LLC) , Jonathan W. Steed (Durham University)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Chemical Science , VOL 2

State: Published (Approved)
Published: July 2020
Diamond Proposal Number(s): 16117 , 222240

Open Access Open Access

Abstract: In this work we develop photoreactive cocrystals/salts of a commercially-important diacetylene, 10,12-pentacosadiynoic acid (PCDA, 1) and report the first X-ray crystal structures of PCDA based systems. The topochemical reactivity of the system is modified depending on the coformer used and correlates with the structural parameters. Crystallisation of 1 with 4,4′-azopyridine (2), 4,4′-bipyridyl (3), and trans-1,2-bis(4-pyridyl)ethylene (4) results in unreactive 2[thin space (1/6-em)]:[thin space (1/6-em)]1 cocrystals or a salt in the case of 4,4′-bipiperidine (5). However, salt formation with morpholine (6), diethylamine (7), and n-butylamine (8), results in highly photoreactive salts 12·7 and 1·8 whose reactivity can be explained using topochemical criteria. The salt 1·6 is also highly photoreactive and is compared to a model morpholinium butanoate salt. Resonance Raman spectroscopy reveals structural details of the photopolymer including its conformational disorder in comparison to less photoactive alkali metal salts and the extent of solid state conversion can be monitored by CP-MAS NMR spectroscopy. We also report an unusual catalysis in which amine evaporation from photopolymerised PCDA ammonium salts effectively acts as a catalyst for polymerisation of PCDA itself. The new photoreactive salts exhibit more reactivity but decreased conjugation compared to the commercial lithium salt and are of considerable practical potential in terms of tunable colours and greater range in UV, X-ray, and γ-ray dosimetry applications.

Subject Areas: Chemistry

Instruments: I19-Small Molecule Single Crystal Diffraction