1,3,5-Tris-[N-(1,10-phenanthrolin-2-yl-carbonyl)aminomethyl]-2,4,6-triethylbenzene (1) was synthesized and its crystal structure was examined. X-ray structural analysis revealed the presence of hydrogen-bonded water molecules as well as hydrogen- and halogen-bonded chloroform molecules in the crystal structure of 1. The 1·H₂O·CHCl₃ associate is stabilized by N–H···O, O–H···N, O–H···O, C–H···O, and C–H···Cl hydrogen bonds as well as C–Cl···O, C–Cl···π, and C–Cl···Cl interactions. Particularly short C–H···O hydrogen bonds with H···O and C···O distances of 1.89 and 2.94 Å, respectively, are observed in the crystal structure. The H···O distance is approximately 30 % shorter than the sum of the van der Waals radii of involved atoms.

¹H NMR spectroscopic titrations in competitive and non-competitive media, as well as binding studies in two-phase systems, such as phase transfer of sugars from aqueous into organic solvents and dissolution of solid carbohydrates in apolar media revealed both highly effective recognition of neutral carbohydrates and interesting binding preferences of an acyclic phenanthroline-based receptor 1. Compared to the previously described acyclic receptors, compound 1 displays significantly higher binding affinities, the rare capability to extract sugars from water into non-polar organic solutions and α- versus β-anomer binding preference in the recognition of glycosides, which differs from those observed for other receptor systems. X-ray crystallographic investigations revealed the presence of water molecules in the binding pocket of 1 that are engaged in the formation of hydrogen-bonding motifs similar to those suggested by molecular modelling for the sugar OH groups in the receptor–sugar complexes. The molecular modelling calculations, synthesis, crystal structure and binding properties of 1 are described and compared with those of the previously described receptors.

Neutral imidazole/aminopyridine- and indole/aminopyridine-based receptors, 1 and 2, have been established as highly effective and selective carbohydrate receptors. These receptors effectively recognise neutral carbohydrates through multiple interactions, including neutral hydrogen bonds and CH⋅⋅⋅π interactions between the sugar CH groups and the aromatic rings of the receptors. The design of these receptors was inspired by the binding motifs observed in the crystal structures of protein–carbohydrate complexes. The formation of very strong complexes with β-glucopyranoside 5, β-maltoside 8, and α-maltoside 9 in organic media has been characterised by ¹H NMR spectroscopy and confirmed by a second, independent technique, namely fluorescence spectroscopy. The syntheses, molecular-modelling studies, binding properties of the receptors 1 and 2 toward selected mono- and disaccharides as well as comparative binding studies with receptors 3 and 4 are described.