Supramolecular light-switchable triazole-hosts for photoresponsive anion binding

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Materials Science

Background:

• Development of responsive materials for molecular recognition.
• Photoswitchable molecules offer tunable binding properties.
• Anion binding studies are crucial for chemical sensing and drug delivery.

Purpose of the Study:

• To design and synthesize novel photoreversible anion binding hosts.
• To investigate the influence of photoswitch isomerization on anion binding affinity.
• To explore the impact of bound anions on the photophysical properties of the hosts.

Main Methods:

• Synthesis of azobenzene and arylazopyrazole based host molecules.
• Incorporation of tetrakis-triazole anion binding motifs.
• Spectroscopic techniques (UV-Vis, NMR) to study binding constants and isomerization.
• Kinetic studies to determine thermal and photoisomerization rates.

Main Results:

• Photoreversible anion binding hosts with azobenzene or arylazopyrazole photoswitches were successfully developed.
• Structural modifications maximized anion binding contrast between E and Z isomers, with Z isomer showing up to 16x higher binding constant.
• Anion binding significantly stabilized the Z-isomer against thermal isomerization, doubling its lifetime.
• Reduced photoisomerization rates and enhanced Z/E ratios in photostationary states correlated with Z-isomer anion binding constants.

Conclusions:

• The developed hosts demonstrate efficient photoreversible anion binding capabilities.
• Anion binding modulates the photophysical properties of the photoswitches, enabling control over isomerization.
• These findings pave the way for light-responsive anion recognition systems.