A Chromo-Fluorogenic Synthetic “Canary” for CO Detection Based on a Pyrenylvinyl Ruthenium(II) Complex

The
chromo-fluorogenic detection of carbon monoxide in air has
been achieved using a simple, inexpensive system based on ruthenium­(II).
This probe shows exceptional sensitivity and selectivity in its sensing
behavior in the solid state. A color response visible to the naked
eye is observed at 5 ppb of CO, and a remarkably clear color change
occurs from orange to yellow at the onset of toxic CO concentrations
(100 ppm) in air. Even greater sensitivity (1 ppb) can be achieved
through a substantial increase in turn-on emission fluorescence in
the presence of carbon monoxide, both in air and in solution. No response
is observed with other gases including water vapor. Immobilization
of the probe on a cellulose strip allows the system to be applied
in its current form in a simple optoelectronic device to give a numerical
reading and/or alarm.