Coumarin Dimer Is an Effective Photomechanochemical AND Gate for Small-Molecule Release

Area of Science:

• Materials Science
• Chemical Engineering
• Organic Chemistry

Background:

• Stimulus-responsive gating of chemical reactions is crucial for advanced applications.
• Existing methods like photocleavable groups and mechanophores offer single-stimulus control (light or force).
• Photomechanochemical gating, using sequential stimuli, has remained undemonstrated.

Purpose of the Study:

• To demonstrate photomechanochemical control of small-molecule release.
• To investigate coumarin dimers as suitable moieties for this dual-stimulus control.
• To explore the tunability of dissociation kinetics and force sensitivity.

Main Methods:

• Density Functional Theory (DFT) calculations to model dimer dissociation kinetics.
• Synthesis and characterization of coumarin dimer derivatives.
• Experimental validation of photomechanochemically controlled release and application in gelation.

Main Results:

• Coumarin dimers exhibit photochemically inert behavior above 300 nm but dissociate under tensile force.
• The resulting coumarins are stable until irradiated, leading to payload release.
• DFT calculations confirmed tunable dissociation rates and predictable force sensitivity via substitution and pulling axis.

Conclusions:

• Coumarin dimers are highly promising for photomechanochemical control of small-molecule release.
• This system allows for precise, sequential control using light and mechanical force.
• Proof-of-concept demonstrated controlled release of aniline and application in bulk gelation.