Metathesis Depolymerization of a Fluorogenic Self-Immolative Polymer

We report a self-immolative polymer (SIP) that generates a fluorescent response upon metathesis depolymerization. Functionally distinct from other degradable polymers, SIPs offer the ability to release many subunits per one signal molecule, making them advantageous for a variety of applications such as molecular detection and signal amplification. Utilizing robust copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry to orthogonally functionalize alkynes, fluorophore coumarin and quencher 4-((4-(dimethylamino)phenyl)azo) (DABCYL) were efficiently installed as side chains on the SIP. The depolymerization mediated by Grubbs 3rd-generation (G3) organoruthenium initiator enabled a fluorescence turn-on response under nanomolar SIP concentrations. To demonstrate the utility of the fluorogenic SIP, we showed a temperature-dependent fluorescence turn-on of this metathesis-triggered SIP using a thermally responsive Grubbs 2nd-generation (G2) organoruthenium initiator.