Visible-Light Responsive Sucrose-Containing Macrocyclic Host for Cations

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Photochemistry

Background:

• Development of photoresponsive host molecules is crucial for advanced materials.
• Chiral macrocycles offer unique binding properties.
• Azobenzene-containing hosts enable light-controlled molecular recognition.

Purpose of the Study:

• To synthesize a novel chiral photoresponsive host molecule (1).
• To investigate the photoisomerization behavior of host 1.
• To explore the alkali metal cation binding properties of both isomers.

Main Methods:

• High-yield Cs2CO3-templated macrocyclization for synthesis.
• Green and blue light irradiation for photoisomerization studies.
• 1H NMR titration and density functional theory (DFT) for binding analysis.

Main Results:

• Host 1 was successfully synthesized via macrocyclization.
• Trans-1 isomerized to a long-lived cis-1 isomer (25-day half-life) upon green light irradiation.
• Both isomers showed preference for potassium (K+) cations, with cis-1 exhibiting stronger binding.
• DFT studies and NMR titrations identified sucrose oxygens and azobenzene nitrogens as key coordination sites.

Conclusions:

• A novel chiral photoresponsive host molecule (1) was synthesized and characterized.
• The host exhibits reversible photoisomerization between trans and cis forms.
• The cis isomer demonstrates enhanced binding affinity for potassium cations, suggesting potential in selective ion sensing or transport.