Doubly N-Confused Hexaphyrin:  A Novel Aromatic Expanded Porphyrin that Complexes Bis-metals in the Core

Abstract

Meso-hexakis(pentafluorophenyl)-substituted doubly N-confused hexaphyrins and their metal complexes were synthesized for the first time, and the structures were elucidated by X-ray single-crystal analyses. The free base form of oxidized hexaphyrin (5) had two preorganized N3O pockets in the macrocyclic core, where a hydrogen-bonding network was formed to keep the molecule planar (the mean plane deviation is 0.054 A). The formation of a planar bis-Cu(II) complex was confirmed by UV/vis, magnetic susceptibility measurements, and X-ray crystallography. The bis-Ni(II) complex (7), on the other hand, was distored from planarity, but it changed to the planar structure upon solvent (acetonitrile) coordination as judged by the observation of a sharp Soret-like band in absorption spectra and the X-ray structures of the complexes.

Figure‐Eight‐Strukturen, Möbius‐Bänder und mehr: Konformation und Aromatizität von Porphyrinoiden

“…[115] Im Folgenden konzentrieren wir uns hauptsächlich auf die reinen Azasysteme und einige ihrer Heteroanaloga. Auslassen werden wir dagegen die Makrocyclen mit N-invertierten Pyrrolen, [233,234] [238] das antiaromatisch ist und die Figure-Eight-Konformation (T2 0 ) annimmt. Ein analoges Redoxpaar wurde später für die meso-trifluormethylierten Derivate gefunden.…”

N‐Confused and N‐Fused meso‐Aryl Sapphyrins

“…[7] In contrast, in the hexaphyrin system, the doubly N-confused dioxohexaphyrins are rather stable and can even be derived from standard hexaphyrins, [8] while the corresponding fused species have not yet been found. Here the question arises as to the relationship between the fate of the confused pyrrole ring and the size of the macrocycles, especially in the sapphyrin system, an intermediate compound between porphyrins and pentaphyrins, and perhaps the oldest member of the expanded porphyrin family.…”

“…The formation of 2 during the synthesis of 1 clearly shows that the ring fusion is a usual phenomenon among N-confused pentapyrrolic macrocycles. [7,8] Our synthetic studies show that 2 can be formed only as a side product when 1 is synthesized by a [5+0] route (path a). We found that 2 can also be made directly from 1 by following a similar strategy as used for the synthesis of NFP [6] (path c).…”

“…On the other hand, in some cases the inverted confused pyrrole ring could stabilize the system by intramolecular hydrogen bonding, as seen in 1 À and doubly Nconfused dioxohexaphyrins. [8] Thus, the repeated introduction of confused rings in the macrocycles would eventually lead to the stable confused porphyrinoids, whose properties are useful. Thus, we believe our confusion approach method will become a powerful strategy to access these novel functional molecules in the near future.…”

Inverted Sapphyrin: A New Family of Doubly N-Confused Expanded Porphyrins

“…on silica gel and treatment with aqueous NH 4 Cl, the inverted sapphyrin 3 was obtained in 8 −9% yield (Scheme 1).…”