Sensing mechanisms of supramolecular porphyrin aggregates: a teamwork task for the detection of gaseous analytes

5,10,15,20-Tetrakis(3,5-dihydroxyphenyl)porphyrin metal derivatives have been exploited as porous sensing layers to functionalize nanogravimetric chemical sensors. Their sensing performances have been tested by exposing the devices to different concentration of volatile compounds. While the peripheral substitution of porphyrin from one side allowed the formation of porous thin films, the other significantly oriented the sensor selectivities towards analytes able to interact by hydrogen bonding. A more intriguing result was the unexpected sensitivity observed toward CO detection, which cannot be ascribed to the CO coordination to the metalloporphyrin sensing layer. In this case the sensing mechanism is due to the entrapment of CO inside the porous porphyrin network, confirming that supramolecular porphyrin aggregates offer a sensing mechanism not available to the single molecular unit.