title: Selective endo and exo binding of mono- and ditopic ligands to a rhomboidal diporphyrin prism.
abstract: Copper(I) can preferentially form heteroleptic complexes containing two phosphine and two nitrogen donors due to steric factors. This preference was employed to direct the self-assembly of a porphyrin-faced rhomboidal prism having two parallel tetrakis(4-iminopyridyl)porphyrinatozinc(II) faces linked by eight 1,4-bis(diphenylphosphino)benzene pillars. The coordination preferences of the Cu(I) ions and geometries of the ligands come together to generate a slipped-cofacial orientation of the porphyrinatozinc(II) faces. This orientation enables selective encapsulation of 3,3'-bipyridine (bipy), which bridges the Zn(II) ions of the parallel porphyrins, whereas 4,4'-bipy exhibits weaker external coordination to the porphyrin faces. Reaction with 2,2'-bipy, by contrast, results in the displacement of the tetratopic porphyrin ligand and formation of [{(2,2'-bipy)Cu(I) }2 (diphosphine)2 ]. The differing strengths of interactions of bipyridine isomers with the system allows for a hierarchy to be deciphered, whereby 4,4'-bipy may be displaced by 3,3'-bipy, which in turn is displaced by 2,2'-bipy.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (UK) http://www-jrn.ch.cam.ac.uk.
authors.forename: Govindasamy
authors.initials: G
authors.lastname: Jayamurugan
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (UK) http://www-jrn.ch.cam.ac.uk.
authors.forename: Derrick A
authors.initials: DA
authors.lastname: Roberts
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (UK) http://www-jrn.ch.cam.ac.uk.
authors.forename: Tanya K
authors.initials: TK
authors.lastname: Ronson
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (UK) http://www-jrn.ch.cam.ac.uk. jrn34@cam.ac.uk.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Nitschke
keywords: N ligands; heteroleptic complexes; host-guest systems; porphyrin assemblies; self-assembly