title: Supramolecular engineering of intrinsic and extrinsic porosity in covalent organic cages.
abstract: Control over pore size, shape, and connectivity in synthetic porous materials is important in applications such as separation, storage, and catalysis. Crystalline organic cage molecules can exhibit permanent porosity, but there are few synthetic methods to control the crystal packing and hence the pore connectivity. Typically, porosity is either 'intrinsic' (within the molecules) or 'extrinsic' (between the molecules)--but not both. We report a supramolecular approach to the assembly of porous organic cages which involves bulky directing groups that frustrate the crystal packing. This generates, in a synthetically designed fashion, additional 'extrinsic' porosity between the intrinsically porous cage units. One of the molecular crystals exhibits an apparent Brunauer-Emmett-Teller surface area of 854 m(2) g(-1), which is higher than that of unfunctionalized cages of the same dimensions. Moreover, connectivity between pores, and hence guest uptakes, can be modulated by the introduction of halogen bonding motifs in the cage modules. This suggests a broader approach to the supramolecular engineering of porosity in molecular organic crystals.
authors: Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
authors: Michael J
authors: MJ
authors: Bojdys
authors: Michael E
authors: ME
authors: Briggs
authors: James T A
authors: JT
authors: Jones
authors: Dave J
authors: DJ
authors: Adams
authors: Samantha Y
authors: SY
authors: Chong
authors: Marc
authors: M
authors: Schmidtmann
authors: Andrew I
authors: AI
authors: Cooper
mesh_terms: D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008958:Models, Molecular; D009930:Organic Chemicals / Q000138:chemical synthesis / Q000737:chemistry*; D010316:Particle Size; D016062:Porosity; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D009930:Organic Chemicals