A dozen years of N-confusion: From synthesis to supramolecular chemistry

Maeda, Hiromitsu; Furuta, Hiroyuki

doi:10.1351/pac200678010029

Pure Appl. Chem., 2006, Vol. 78, No. 1, pp. 29-44

http://dx.doi.org/10.1351/pac200678010029

A dozen years of N-confusion: From synthesis to supramolecular chemistry*

Hiromitsu Maeda^1,2,3 and Hiroyuki Furuta²

¹ Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
² Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan
³ Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan

Abstract: The chemistry of N-confused porphyrin (NCP) and its analogs started in 1994. Since then, considerable progress has been made in understanding the unique properties of NCP and its analogs, which confer characteristic reactivity and metal complex formation. The evolved isomers, multiply NCPs, and expanded N-confused derivatives, have opened up new realms of NCP chemistry. Cis- and trans-doubly N-confused porphyrin (N₂CP) stabilizes higher oxidation states such as Cu^III in square-planar fashion in the core. Confused isomers with five or more pyrrole rings can coordinate several cations owing to their larger cavities compared to tetrapyrrolic system. The peripheral nitrogen(s) of NCP and its analogs can serve as hydrogen-bonding donor and acceptor, and metal coordination site as well. For example, NCP forms versatile dimers with the assistance of metal ions. The square-planar divalent metal complexes of C₆F₅-substituted NCP act as efficient anion-binding receptors. Furthermore, Cu^III complexes of N₂CP, possessing both N and NH at the periphery, form self-assembled one-dimensional (1D) hydrogen-bonding networks, whose orientations differ in cis (zigzag) and trans (straight) isomers.

*Pure Appl. Chem. 78, 1-64 (2006). A collection of invited, peer-reviewed articles by the winners of the 2005 IUPAC Prize for Young Chemists.