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Issue 22, 2017
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A combined crystallographic and theoretical study of weak intermolecular interactions in crystalline squaric acid esters and amides

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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-aminoethyl)pyridinium salt (5). All compounds form interesting supramolecular assemblies in the solid state that have been analyzed using high level DFT calculations and 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 is crucial for the formation of the supramolecular assemblies in the solid state.

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

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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, 2017,19, 3071-3077
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    A combined crystallographic and theoretical study of weak intermolecular interactions in crystalline squaric acid esters and amides

    R. Prohens, A. Portell, M. Font-Bardia, A. Bauzá and A. Frontera, CrystEngComm, 2017, 19, 3071
    DOI: 10.1039/C7CE00556C

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