A subtle interplay of C-H hydrogen bonds in complexation of anions of varied dimensionality by a nitro functionalized tripodal podand

The structural aspects of binding of halides (1 and 2), nitrate (3), perchlorate (4), trifluoroacetate (5) and hexafluorosilicate (6) with the protonated tripodal podand L are examined crystallographically. Anion binding with multiple receptor units is attributable entirely to the (NH)(+)center dot center dot center dot anion and multiple C-H center dot center dot center dot anion hydrogen bonding interactions in all six complexes. Protonation at the apical nitrogen and presence of nitro functionality renders the methylene and aryl hydrogen sufficiently acidic for their active participation in moderate to weak CH center dot center dot center dot anion interactions are noteworthy. All supramolecular networks of complexes 1-6 are guided by various non-convalent interactions, especially directional CH center dot center dot center dot O-nitro hydrogen bonds and pi-stacking interactions.