title: Monomeric Chiral and Achiral Basket-Handle Porphyrins: Synthesis, Structural Features, and Arrested Tautomerism.
abstract: Chiral and achiral basket-handle porphyrins (BHPs) with different p-xylene straps and peripheral solubilizing groups were synthesized using a previously established synthetic approach. Subsequent modification, functionalization, and metalation of the tetrapyrrolic macrocycle yielded more than 80 BHPs. The chiral representatives were resolved into their enantiomers, whose absolute configurations were determined by comparison of their ECD spectra with other experimental or quantum chemically calculated spectra. NMR studies and coupled-cluster calculations proved that the free base BHPs, although highly symmetric, exhibited the phenomenon of "arrested tautomerism". Comparison of the solid-state structures of three metalated BHPs offered detailed insight into their three-dimensional shape. Finally, directly linked dimeric porphyrins with a BHP subunit were synthesized from functionalized BHPs to prove their value as synthetic building blocks.
authors.affiliation: Institute of Organic Chemistry and ‡Institute of Inorganic Chemistry, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Andreas C
authors.initials: AC
authors.lastname: Gehrold
authors.affiliation: Institute of Organic Chemistry and ‡Institute of Inorganic Chemistry, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Bruhn
authors.affiliation: Institute of Organic Chemistry and ‡Institute of Inorganic Chemistry, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Heidi
authors.initials: H
authors.lastname: Schneider
authors.affiliation: Institute of Organic Chemistry and ‡Institute of Inorganic Chemistry, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Radius
authors.affiliation: Institute of Organic Chemistry and ‡Institute of Inorganic Chemistry, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bringmann