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A combined crystallographic and theoretical study of weak intermolecular interactions in crystalline squaric acid esters and amides

Abstract

We report the synthesis and X-ray solid state structures of five squaric acid derivatives, i.e. a zwitterionic compound namely 3-Hydroxy-4-(2-pyridin-2-yl-ethylamino)-cyclobut-3-ene-1,2-dione (1); a squaramide monoester, 3-Ethoxy-4-(2-pyridin-2-yl-ethylamino)-cyclobut-3-ene-1,2-dione (2); two differently solvated (EtOH and DMSO/water) disquaramides 3,4-bis((4-hydroxyphenethyl)amino)cyclobut-3-ene-1,2-dione (3 and 4, respectively); and a mixed hydrogen squarate and disquarate 2-(2-Amino-ethyl)-pyridinium salt (5). All compounds form interesting supramolecular assemblies in the solid state that have been analyzed using high level DFT calculations and the Bader's theory of “atoms-in-molecules”. An intricate combination of ion-pair and H-bonding interactions along with π–π stacking and anion–π contacts of the cyclobutenedione rings are crucial for the formation of the supramolecular assemblies in the solid state.

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Publication details

The article was received on 23 Mar 2017, accepted on 07 May 2017 and first published on 08 May 2017


Article type: Paper
DOI: 10.1039/C7CE00556C
Citation: CrystEngComm, 2017, Accepted Manuscript
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    A combined crystallographic and theoretical study of weak intermolecular interactions in crystalline squaric acid esters and amides

    R. Prohens, A. Frontera, A. Portell, M. Font-Bardia and A. Bauza, CrystEngComm, 2017, Accepted Manuscript , DOI: 10.1039/C7CE00556C

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