title: Controlling the crystallization of porous organic cages: molecular analogs of isoreticular frameworks using shape-specific directing solvents.
abstract: Small structural changes in organic molecules can have a large influence on solid-state crystal packing, and this often thwarts attempts to produce isostructural series of crystalline solids. For metal-organic frameworks and covalent organic frameworks, this has been addressed by using strong, directional intermolecular bonding to create families of isoreticular solids. Here, we show that an organic directing solvent, 1,4-dioxane, has a dominant effect on the lattice energy for a series of organic cage molecules. Inclusion of dioxane directs the crystal packing for these cages away from their lowest-energy polymorphs to form isostructural, 3-dimensional diamondoid pore channels. This is a unique function of the size, chemical function, and geometry of 1,4-dioxane, and hence, a noncovalent auxiliary interaction assumes the role of directional coordination bonding or covalent bonding in extended crystalline frameworks. For a new cage, CC13, a dual, interpenetrating pore structure is formed that doubles the gas uptake and the surface area in the resulting dioxane-directed crystals.
authors.affiliation: Department of Chemistry and Centre for Materials Discovery, University of Liverpool , Crown St., Liverpool L69 7ZD, United Kingdom.
authors.forename: Tom
authors.initials: T
authors.lastname: Hasell
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Culshaw
authors.forename: Samantha Y
authors.initials: SY
authors.lastname: Chong
authors.forename: Marc
authors.initials: M
authors.lastname: Schmidtmann
authors.forename: Marc A
authors.initials: MA
authors.lastname: Little
authors.forename: Kim E
authors.initials: KE
authors.lastname: Jelfs
authors.forename: Edward O
authors.initials: EO
authors.lastname: Pyzer-Knapp
authors.forename: Hilary
authors.initials: H
authors.lastname: Shepherd
authors.forename: Dave J
authors.initials: DJ
authors.lastname: Adams
authors.forename: Graeme M
authors.initials: GM
authors.lastname: Day
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Cooper