Crystallographic and Theoretical Evidence of Anion–π and Hydrogen-Bonding Interactions in a Squaramide–Nitrate Salt



Synthetic anionic receptors are fundamental to the understanding of the mechanism of recognition phenomena, which is the basis of many fundamental biological processes. Recognition studies and X-ray crystallography techniques provide accurate information on the structure of the molecular complexes and the nature of the interactions involved. Here, we present the first example of a squaramide–nitrate salt. X-ray crystallography and theoretical studies show the important roles of anion–π and hydrogen-bonding interactions in the crystal packing of this compound in relation to those found in the free squaramide solid structure.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)