Photodimerization-Triggered Photopolymerization of Triene Coordination Polymers Enables Macroscopic Photomechanical...

Area of Science:

• Materials Science
• Polymer Chemistry
• Photochemistry

Background:

• Controlling molecular packing in crystals is crucial for solid-state [2 + 2] photocycloaddition reactions.
• This control is essential for synthesizing photocontrolled smart materials.
• Coordination polymers (CPs) offer a platform for precise molecular arrangement.

Purpose of the Study:

• To report the stepwise photodimerization-triggered photopolymerization of two triene coordination polymers (CPs).
• To investigate the synthesis of novel organic polymers using olefinic CP platforms.
• To explore the development of photocontrolled smart materials based on light-induced transformations.

Main Methods:

• Synthesis and characterization of two triene coordination polymers (CPs): {[Zn(2-BBA)₂(tpeb)]·0.5CH₃CN} (1) and {[Zn(3-BBA)₂(tpeb)]·CH₃CN)} (2).
• Single-crystal to single-crystal (SCSC) transformations triggered by specific light irradiation (420 nm and UV light).
• Photomechanical motion studies on single crystals and composite films (1-PVA).

Main Results:

• Stepwise [2 + 2] photocycloaddition reactions observed in CPs 1 and 2 upon light irradiation, leading to photodimerization and subsequent photopolymerization.
• SCSC transformations resulted in the formation of ladder-like coordination chains and extended polymer networks.
• Photomechanical motions (bending, cracking, jumping) and photodriven swimming were observed in CP crystals and films.

Conclusions:

• The study successfully demonstrates a method to enable photodimerization of photoinactive olefin pairs within CPs.
• A new route for synthesizing organic polymers is established using olefinic CP platforms.
• The findings open avenues for designing advanced photocontrolled smart materials with tunable photomechanical responses.