Metalloporphyrins based artificial olfactory receptors

Metalloporphyrins offer almost unique opportunities to design artificial receptors for chemical sensors. These molecules can be tailored, at the synthetic level, changing in a almost controlled way the sensor selectivity that can be oriented toward desired analyte families. Optical and electrochemical properties of metalloporphyrins are known since several years and they have been adequately exploited as potentiometric sensors for ions in solutions. In gas sensing the optical characteristics were utilized to detect gases like O2 and NO2 for which metalloporphyrins have a good selectivity. In gas environment, beside these gases the interactions are very rich but rather unselective, nonetheless this feature is interesting for artificial olfaction where a certain degree of cross-selectivity is required. As a consequence, arrays of gas sensors based on metalloporphyrins and optical and mass transducers have been demonstrated in the last decade. In this paper the properties of such arrays are reviewed evidencing the high flexibility of such sensors and their wide spectrum of applications.