title: Cyclo[6]pyridine[6]pyrrole: a dynamic, twisted macrocycle with no meso bridges.
abstract: A large porphyrin analogue, cyclo[6]pyridine[6]pyrrole, containing no meso bridging atoms, has been synthesized through Suzuki coupling. In its neutral form, this macrocycle exists as a mixture of two figure-eight conformers that undergo fast exchange in less polar solvents. Upon protonation, the dynamic twist can be transformed into species that adopt a ruffled planar structure or a figure-eight shape depending on the extent of protonation and counteranions. Conversion to a bisboron difluoride complex via deprotonation with NaH and treatment with BF3 acts to lock the macrocycle into a figure-eight conformation. The various forms of cyclo[6]pyridine[6]pyrrole are characterized by distinct NMR, X-ray crystallographic, and spectroscopic features.
authors.affiliation: Department of Chemistry, The University of Texas at Austin , 105 East 24th Street, Stop A5300, Austin, Texas 78712-1224 United States.
authors.forename: Zhan
authors.initials: Z
authors.lastname: Zhang
authors.forename: Won-Young
authors.initials: WY
authors.lastname: Cha
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Williams
authors.forename: Elise L
authors.initials: EL
authors.lastname: Rush
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Ishida
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Lynch
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Sessler