Diastereoselective cyclization in chiral diarylethene crystals: polymorphism and selectivity

Area of Science:

• Organic Chemistry
• Crystallography
• Photochemistry

Background:

• Photochromic diarylethenes are molecules that change color upon light exposure.
• Controlling the stereochemistry of photochromic reactions is crucial for advanced applications.
• Crystalline environments can influence molecular reactions.

Purpose of the Study:

• To synthesize an optically active photochromic diarylethene.
• To investigate the photochromic behavior of the diarylethene in solution and crystalline states.
• To determine if the crystalline phase influences the stereochemical outcome of the photochromic reaction.

Main Methods:

• Synthesis of optically active diarylethene (S)-1a.
• Characterization of crystalline phases (alpha and beta).
• Photochromic reaction studies in solution and single crystals.

Main Results:

• The diarylethene (S)-1a was successfully synthesized and formed alpha- and beta-crystalline phases.
• Photochromic reactions occurred in both solution and crystalline phases.
• Diastereoselective photochromism was observed exclusively in the beta-crystalline phase, yielding (S,R,R)-1b.
• No diastereoselection was observed in solution or the alpha-crystalline phase.

Conclusions:

• The crystalline environment, specifically the beta-phase, can induce high diastereoselectivity in the photochromic reaction of diarylethenes.
• This finding highlights the potential of solid-state control over molecular transformations.
• Optically active diarylethenes offer opportunities for developing stereoselective photochromic materials.