Synthesis, structure and binding properties of a series of dissymmetric resorcin[4]arene-based cavitands

The synthesis of four new dissymmetric cavitands is reported. These deep-walled receptors are constructed from a resorcin[4]arene scaffold bearing anti-disposed quinoxaline substituents, with either N-haloalkyl-diazaphthalimide (1), dinitrophenyl (2) or diaminophenyl (3) moieties as the other wall components. The structure and inclusion properties of 1 and 2 have been probed in solution by NMR spectroscopy and notably in the solid-state by X-ray crystallography. The diazaphthalimide-based compounds 1 crystallise as 1:1 host-guest complexes with chloroform, with the resorcin[4]arene scaffolds adopting pinched cone conformations. Conversely, the dinitrophenyl-variant 2 features a more open, symmetric structure in the solid-state and co-crystallises with two acetone molecules within the central cavity. Preliminary binding experiments in mesitylene-d12 at 303 K demonstrate 1 (Kapp = 5 × 102 M−1) and 2 (Kapp = 2 × 102 M−1) are effective hosts for cyclohexane guest molecules in the absence of competitive solvent inclusion.

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