Charge Density Studies of Weak Interactions in Dipicrylamine

Abstract

A low-temperature high-resolution X-ray and neutron diffraction study of charge distribution in the superacid dipicrylamine (DPA) has been carried out. This structure exhibits interesting weak interactions including bifurcated N-H‚‚‚O and C-H‚‚‚O H-bonds which consolidate it. The corresponding interaction lines appear to be modified in the vicinity of the critical points of the covalent bonds of the hydrogen atoms. The presence of six nitro groups generates some short N‚‚‚O contacts. On the basis of the experimental interaction paths, an attractive interaction is found, in agreement with the prediction of such an effect from earlier model ab initio calculations performed for simple dimers. For these weak interactions, a linear relationship is found between the charge density at the interaction critical points and the N-O distance. † Dedicated to Prof. T. M. Krygowski on his 65th birthday.

σ‐Hole and π‐Hole Synthon Mimicry in Third‐Generation Crystal Engineering: Design of Elastic Crystals

“…in a comparison with the σ‐hole on halogens and it explains the orthogonal geometry. Charge density analysis showed the presence of interaction lines and bond critical points (bcp) for such interactions, even at distances longer than the sum of van der Waals (vdW) contacts . Both types (σ‐ and π‐hole) are very similar in nature and the importance of the latter has been highlighted by Frontera and co‐workers .…”

“…Both types (σ‐ and π‐hole) are very similar in nature and the importance of the latter has been highlighted by Frontera and co‐workers . Carbonyl⋅⋅⋅ carbonyl contacts, studied by Diederich and co‐workers, and nitro⋅⋅⋅nitro orthogonal interactions, studied by Wozniak and co‐workers, are typical examples of such π‐hole‐based synthons. Carbonyl⋅⋅⋅carbonyl contacts in crystalline aldehydes are even more exciting as they are less studied from a crystal engineering perspective and certainly not in any property engineering of solids.…”

Selective Precipitation of Alkaline Earth Metal Cations with Dipicrylamine Anion: Structure–Selectivity Correlation

“…Recently, crystal structures of DPA and a computational study on the intermolecular interactions observed in the crystal structure have been reported. [1] The crystal structures of some of its organic salts have also been reported.…”

Influence of Urea N–H Acidity on Receptor–Anionic and Neutral Analyte Binding in a Ruthenium(II)–Polypyridyl‐Based Colorimetric Sensor

“…Similar non-bonded attractive interactions have been reported. [23] Binding Studies with DMSO and DMF In our attempt to resolve the 1 H NMR spectroscopic signals for the urea protons in receptors 2 and 3, the spectra for the respective receptors were recorded in [D 6 ]DMSO and [D 7 ]DMF. In both cases, broad and apparently downfield-shifted bands were observed.…”