Synthesis of Dithienylcycloalkene Molecular Switches Enabled by a Bench-Stable Ti-Complex

Area of Science:

• Organic Chemistry
• Materials Science
• Photochemistry

Background:

• Dithienylethenes (DTEs) are photochromic molecular switches.
• Cycloalkene-bridged DTEs offer tunable properties.
• Previous synthetic methods for DTEs can be challenging.

Purpose of the Study:

• To synthesize a series of cycloalkene-bridged DTEs with varying ring sizes.
• To evaluate the impact of ring strain on DTE photoswitching performance.
• To develop a more practical synthetic route for DTE analogs.

Main Methods:

• Synthesis of 4- to 7-membered ring cycloalkene-bridged DTEs via McMurry coupling.
• Utilized a bench-stable Ti(IV)-complex reagent for improved synthesis.
• Alternative strategy for synthesizing 3-membered cyclopropene-bridged DTEs.

Main Results:

• McMurry coupling efficiency varied with ring size, with lower yields for larger rings.
• Cyclopropene-bridged DTEs were synthesized via an alternative method.
• DTEs with cyclobutene bridges exhibited enhanced reversibility and fatigue resistance.

Conclusions:

• The developed synthetic method offers improved practicality and reproducibility.
• Cyclobutene-bridged DTEs represent a promising class of molecular switches.
• Ring strain significantly influences the photoswitching performance of DTEs.