Encoding and Expressing the Handedness of a Möbius π System in a Totemic Architecture

Area of Science:

• Supramolecular Chemistry
• Organic Electronics
• Chiroptical Materials

Background:

• Controlling chirality in Möbius π systems is crucial for molecular information processing.
• Redox-driven control offers a novel pathway for manipulating molecular chirality.
• Möbius aromatic systems present unique electronic and structural properties.

Purpose of the Study:

• Investigate the redox behavior of Ni(II) and Pd(II) complexes with a Möbius aromatic [28]hexaphyrin linked to α-cyclodextrin.
• Explore the generation and manipulation of pseudoenantiomers with distinct chiroptical signatures.
• Demonstrate a reversible shape-shifting process exhibiting chiral memory and robust chiroptical switching.

Main Methods:

• Synthesis of Ni(II) and Pd(II) complexes of a Möbius aromatic [28]hexaphyrin doubly linked to α-cyclodextrin.
• Spectroelectrochemical studies to analyze redox-induced structural and electronic changes.
• Chiroptical spectroscopy to monitor changes in chirality and optical properties.

Main Results:

• Coordination with Ni(II) and Pd(II) generates pseudoenantiomeric pairs with opposite chiroptical signatures.
• Oxidation of Ni(II) complexes preserves Möbius conformation with interrupted π-systems.
• Oxidation of Pd(II) complexes converts Möbius systems to Hückel aromaticity, retaining chirality from the cyclodextrin scaffold.
• Reduction of oxidized Pd(II) complexes shows high stereoselectivity, demonstrating chiral memory.
• Both Ni(II) and Pd(II) complexes exhibit robust, reversible ON-OFF chiroptical switching.

Conclusions:

• Redox processes can effectively control the chirality of Möbius π systems.
• The investigated totemic architecture enables a chiral memory phenomenon through reversible shape-shifting.
• Robust ON-OFF chiroptical switches based on Möbius π systems have been achieved, opening avenues for molecular electronics.