Mechanically Triggered Carbon Monoxide Release with Turn-On Aggregation-Induced Emission.

Area of Science:

• Polymer Chemistry
• Materials Science
• Mechanochemistry

Background:

• Mechanoresponsive polymers are crucial for developing advanced materials for catalysis, sensing, and dynamic therapy.
• Expanding the functional capabilities of these materials necessitates the discovery of new chemistries for small molecule release.
• Current mechanophores often rely on scissile bonds, limiting their application scope.

Purpose of the Study:

• To introduce a novel nonscissile bifunctional mechanophore based on norborn-2-en-7-one (NEO).
• To demonstrate dual mechano-activated properties: small molecule release and fluorescence emission.
• To explore a new strategy for force-responsive small molecule release and aggregation-induced emission (AIE) luminogens.

Main Methods:

• Synthesis of a bifunctional mechanophore incorporating the norborn-2-en-7-one (NEO) unit.
• Activation via pulsed solution ultrasonication to induce mechanochemical reactions.
• Characterization of carbon monoxide (CO) release and fluorescence properties of the polymer product.

Main Results:

• The mechanophore demonstrated nonscissile release of carbon monoxide (CO) upon ultrasonication.
• High molecular weight polymers (158.8 kDa) achieved a 58% CO release efficiency (~154 CO molecules per chain).
• The macromolecular product exhibited bright cyan fluorescence in aggregated states, acting as a turn-on sensor for CO release.

Conclusions:

• A unique nonscissile mechanophore strategy for controlled small molecule release has been successfully demonstrated.
• The developed system offers a dual-response capability, combining CO release with aggregation-induced emission (AIE).
• This work provides a foundation for designing advanced force-responsive materials with integrated sensing and release functionalities.