Chromogenesis-based Resonance Raman molecular sensor for reactive oxygen species

•Resonance Raman sensor responsive to reactive oxygen species is reported.•The non-resonant hydrazo sensor undergoes a colored azo form by hypochlorite.•The chromogenic process turns on resonance-enhanced Raman scattering.

Here we report a novel design concept for a molecular sensing platform that specifically generates under non-toxic visible laser excitation, resonance Raman signatures of nitrile (∼2200 cm−1) in response to reactive oxygen species (ROS). The sensing principle employs a ROS-triggered oxidative chromogenic reaction that activates resonance Raman enhancement through chemical transformation of a non-resonant hydrazo molecule into a resonant azo dye with extended π-conjugation. Experimental studies as well as DFT calculation demonstrate that such a design strategy for activatable resonance Raman sensor is valid for selective detection of highly oxidative ROS, hypochlorite ions in the present case, down to 100 ppm.

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