All Visible Light Photoswitch Based on the Dimethyldihydropyrene Unit Operating in Aqueous Solutions with High...

Area of Science:

• Materials Science
• Photochemistry
• Supramolecular Chemistry

Background:

• Photochromic compounds offer light-tunable properties for advanced materials and biological applications.
• Existing systems often require UV light, limiting their use in biological settings and necessitating aqueous compatibility.

Purpose of the Study:

• To design and synthesize a novel photochromic molecule activated by visible light.
• To ensure the molecule functions effectively in aqueous media, avoiding harmful UV radiation.
• To investigate its photoswitching capabilities and potential for electrocatalytic control.

Main Methods:

• Synthesis of a benzo[e]-fused dimethyldihydropyrene derivative with a methyl-pyridinium group.
• Photoisomerization studies using visible light (680 nm for opening, 470 nm for closing).
• Characterization via nuclear magnetic resonance (NMR) and absorption spectroscopy, supported by time-dependent density functional theory (TD-DFT) calculations.

Main Results:

• The synthesized compound reversibly isomerizes between closed and open (cyclophanediene) forms upon visible light irradiation.
• High quantum yields were observed for both photo-opening (14.5% at 680 nm) and photo-closing (quantitative at 470 nm) in water.
• The photoswitching mechanism was elucidated through spectroscopic and computational analyses.
• Electrocatalytic triggering of the isomerization from the open to the closed form was demonstrated.

Conclusions:

• A novel photochromic system operating in water with visible light has been developed.
• The system exhibits efficient and reversible photoswitching, suitable for biological applications.
• The compound's isomerization can be controlled by both light and electrocatalysis, offering versatile applications.