Prohens López, RafaelPortell Bueso, AnnaFont Bardia, Ma. MercedesBauzá, AntonioFrontera, Antonio2020-06-022020-06-022017-05-081466-8033https://hdl.handle.net/2445/163714We 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-bisIJ(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 ionpair 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.27 p.application/pdfeng(c) Prohens López, Rafael et al., 2017Cristal·lografiaÈstersAmidesCrystallographyEstersAmidesinfo:eu-repo/semantics/article6768472020-06-02info:eu-repo/semantics/openAccess