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Updated: Nov 19, 2025

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Crystal structure and halogen-hydrogen bonding of a Delépine reaction inter-mediate
David Z T Mulrooney1, Helge Müller-Bunz1, Tony D Keene1
1School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
Abstract:
The reaction of 1,5-di-bromo-pentane with urotropine results in crystals of the title mol-ecular salt, 5-bromo-urotropinium bromide [systematic name: 1-(5-bro-mo-pent-yl)-3,5,7-tri-aza-1-azoniatri-cyclo-[3.3.1.13,7]decane bromide], C11H22BrN4 +·Br- (1), crystallizing in space group P21/n. The packing in compound 1 is directed mainly by H⋯H van der Waals inter-actions and C-H⋯Br hydrogen bonds, as revealed by Hirshfeld surface analysis. Comparison with literature examples of alkyl-urotropinium halides shows that the inter-actions in 1 are consistent with those in other bromides and simple chloride and iodide species.
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