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Updated: Mar 31, 2026

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Hexaphyrin-Cyclodextrin Hybrids: A Nest for Switchable Aromaticity, Asymmetric Confinement, and Isomorphic
Mickaël Ménand1,2, Matthieu Sollogoub3,4, Bernard Boitrel5
1Sorbonne Universités, UPMC Univ Paris 06, Institut Parisien de Chimie Moléculaire (UMR CNRS 8232; France). mickael.menand@upmc.fr.
Abstract:
Conformational control over the highly flexible π-conjugated system of expanded porphyrins is a key step toward the fundamental understanding of aromaticity and for the development of molecular electronics. We have synthesized unprecedented hexaphyrin-cyclodextrin (HCD) capped hybrids in which the hexaphyrin part is constrained in a planar rectangular conformation in either a 26 or a 28 π-electron oxidation state ([26]/[28]HCD). These structures display strong aromaticity and antiaromaticity, respectively, exhibit markedly different chiroptical properties, and are interconvertible upon the addition of DDQ or NaBH(OAc)3, thus affording a rare switchable aromatic-antiaromatic system with a free-base expanded porphyrin. Conformational analysis revealed discrimination of the two coordination sites of the hexaphyrin, one of which was coupled to a confined asymmetric environment, and fluxional behavior consisting of apparent rotation of the hexaphyrin cap through a shape-shifting mechanism.
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