Substituent interference on supramolecular assembly in urea gelators: synthesis, structure prediction and NMR

Piana, Francesca, Case, David H., Campos E Menezes Jorge Ramalhete, Susana, Pileio, Giuseppe, Facciotti, Marco, Day, Graeme M., Khimyak, Yaroslav, Angulo, Jesus, Brown, Richard C. D. and Gale, Philip A. (2016) Substituent interference on supramolecular assembly in urea gelators: synthesis, structure prediction and NMR. Soft Matter, 12 (17). pp. 4034-4043. ISSN 1744-683X

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Abstract

Eighteen N-aryl-N'-alkyl urea gelators were synthesised in order to understand the effect of head substituents on gelation performance. Minimum gelation concentration values obtained from gel formation studies were used to rank the compounds and revealed the remarkable performance of 4-methoxyphenyl urea gelator 15 in comparison to 4-nitrophenyl analogue 14, which could not be simply ascribed to substituent effects on the hydrogen bonding capabilities of the urea protons. Crystal structure prediction calculations indicated alternative low energy hydrogen bonding arrangements between the nitro group and urea protons in gelator 14, which were supported experimentally by NMR spectroscopy. As a consequence, it was possible to relate the observed differences to interference of the head substituents with the urea tape motif, disrupting the order of supramolecular packing. The combination of unbiased structure prediction calculations with NMR is proposed as a powerful approach to investigate the supramolecular arrangement in gel fibres and help understand the relationships between molecular structure and gel formation.

Item Type: Article
Additional Information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Faculty \ School: Faculty of Science > School of Pharmacy
Faculty of Science
Depositing User: Pure Connector
Date Deposited: 23 Mar 2016 15:01
Last Modified: 04 Nov 2020 00:44
URI: https://ueaeprints.uea.ac.uk/id/eprint/58010
DOI: 10.1039/C6SM00607H

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