title: A New Approach to Non-Coordinating Anions: Lewis Acid Enhancement of Porphyrin Metal Centers in a Zwitterionic Metal-Organic Framework.
abstract: We describe a new strategy to generate non-coordinating anions using zwitterionic metal-organic frameworks (MOFs). By assembly of anionic inorganic secondary building blocks (SBUs) ([In(CO2)4](-)) with cationic metalloporphyrin-based organic linkers, we prepared zwitterionic MOFs in which the complete internal charge separation effectively prevents the potential binding of the counteranion to the cationic metal center. We demonstrate the enhanced Lewis acidity of Mn(III)- and Fe(III)-porphyrins in the zwitterionic MOFs in three representative electrocyclization reactions: [2 + 1] cycloisomerization of enynes, [3 + 2] cycloaddition of aziridines and alkenes, and [4 + 2] hetero-Diels-Alder cycloaddition of aldehydes with dienes. This work paves a new way to design functional MOFs for tunable chemical catalysis.
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Johnson
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
authors.forename: Brenna M
authors.initials: BM
authors.lastname: Petersen
authors.affiliation: Chemical Biology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Magyar tudósok krt. 2, H-1117 Budapest, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Kormos
authors.affiliation: Department of Physics and Astronomy, Theodore Jorgensen Hall, 855 N 16th St., University of Nebraska , Lincoln, Nebraska 68588-0299, United States.
authors.forename: Elena
authors.initials: E
authors.lastname: Echeverría
authors.affiliation: ChemMatCARS, Center for Advanced Radiation Sources, The University of Chicago , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Yu-Sheng
authors.initials: YS
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang