An AAAA–DDDD quadruple hydrogen-bond array

Abstract

Secondary electrostatic interactions between adjacent hydrogen bonds can have a significant effect on the stability of a supramolecular complex. In theory, the binding strength should be maximized if all the hydrogen-bond donors (D) are on one component and all the hydrogen-bond acceptors (A) are on the other. Here, we describe a readily accessible AAAA–DDDD quadruple hydrogen-bonding array that exhibits exceptionally strong binding for a small-molecule hydrogen-bonded complex in a range of different solvents (Ka > 3 × 1012 M–1 in CH2Cl2, 1.5 × 106 M–1 in CH3CN and 3.4 × 105 M–1 in 10% v/v DMSO/CHCl3). The association constant in CH2Cl2 corresponds to a binding free energy (ΔG) in excess of –71 kJ mol–1 (more than 20% of the thermodynamic stability of a carbon–carbon covalent bond), which is remarkable for a supramolecular complex held together by just four intercomponent hydrogen bonds. The stability of multiply hydrogen-bonded complexes can be influenced significantly by secondary electrostatic interactions between the pairs of atoms in adjacent hydrogen bonds. Now, a quadruple hydrogen-bonding array in which all of the donors are located in one component and all of the acceptors in the other has been shown to form complexes that are exceptionally stable.

Cite this article

Blight, B., Hunter, C., Leigh, D. et al. An AAAA–DDDD quadruple hydrogen-bond array. Nature Chem 3, 244–248 (2011). https://doi.org/10.1038/nchem.987

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