Diphenanthrioctaphyrin(1.1.1.0.1.1.1.0): Conformational Switching Controls the Stereochemical Dynamics of the Topologically Chiral System

The
analogue of octaphyrin(1.1.1.0.1.1.1.0) bearing two dimethoxyphenanthrene
units was synthesized and characterized in solution and solid state.
The macrocycle was demonstrated to exist as two locked conformers
that can be easily separated and handled individually. The conversion
of conformers was proven to be facilitated by the presence of hydrogen-bond
acceptors, such as amines. The bis-boron­(III) complex of diphenanthrioctaphyrin
has been obtained, proving that the metalloid center acts as the topology
selector stabilizing only one conformation of the macrocycle, irrespective
of the stereoisomer used for the insertion. Both conformers of diphenanthrioctaphyrin,
as well as the boron complex formed from them, have been separated
into enantiomers using HPLC with a chiral stationary phase. All of
these systems have shown strikingly different stereodynamic behavior.