posted on 2022-01-12, 17:04authored byYunyan Sun, William J. Neary, Zachary P. Burke, Hai Qian, Lingyang Zhu, Jeffrey S. Moore
Polymers that release functional
small molecules under mechanical
stress potentially serve as next-generation materials for catalysis,
sensing, and mechanochemical dynamic therapy. To further expand the
function of mechanoresponsive materials, the discovery of chemistries
capable of small molecule release are highly desirable. In this report,
we detail a nonscissile bifunctional mechanophore (i.e., dual mechano-activated
properties) based on a unique mechanochemical reaction involving norborn-2-en-7-one
(NEO). One property is the release of carbon monoxide (CO) upon pulsed
solution ultrasonication. A release efficiency of 58% is observed
at high molecular weights (Mn = 158.8
kDa), equating to ∼154 molecules of CO released per chain.
The second property is the bright cyan emission from the macromolecular
product in its aggregated state, resulting in a turn-on fluorescence
readout coincident with CO release. This report not only demonstrates
a unique strategy for the release of small molecules in a nonscissile
way but also guides future designs of force-responsive aggregation-induced
emission (AIE) luminogens.