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Two reported [26] and [28]hexaphyrins are analyzed via measured and computed geome
tries and NMR-shieldings as examples of respectively4
n + 2
![](/images/gifchars/pi.gif)
-elec
tron aromatic and 4
n ![](/images/gifchars/pi.gif)
-elec
tron antiaromatic double-twist M&
ouml;bius ring systems, adopting a lemniscular/figure-eight topologywith linking number
LK = 2
![](/images/gifchars/pi.gif)
. Values of local twist (
TW) and nonlocal writhe (
WR) derived from the relation
Lk =
Tw +
WR appear relativelyinsensitive to the aromatic/antiaromatic character. The [26]hexaphyrin may adopt differing solution and solid-state conformations.