title: 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 (K(a) > 3 × 10(12) M(-1) in CH2Cl2, 1.5 × 10(6) M(-1) in CH3CN and 3.4 × 10(5) 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.
authors.affiliation: School of Chemistry, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh EH9 3JJ, UK.
authors.forename: Barry A
authors.initials: BA
authors.lastname: Blight
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Hunter
authors.forename: David A
authors.initials: DA
authors.lastname: Leigh
authors.forename: Hamish
authors.initials: H
authors.lastname: McNab
authors.forename: Patrick I T
authors.initials: PI
authors.lastname: Thomson
mesh_terms: D002244:Carbon / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D012997:Solvents; D002244:Carbon; D006859:Hydrogen