New iron sensors for detection of food containing protein freshness

In recent years, more attention has been focused on the efficient detection of chemical pollutants, especially volatile organic compounds (VOCs) and hazardous gases (HGs), using various electronic sensors. This area is really growing given the current challenges in highly toxic molecules detection in our daily life, due to pollution and health domestic issues. In particular, the detection of relatively small volatile molecules at room temperature, is challenging at low concentration levels, and there is therefore a need to develop new sensitive sensors at lower costs. In this frame, we have recently initiated a new research project based on our long term experience in the construction of iron based coordination polymers with azole based ligands,1 for which intriguing spin crossover properties were disclosed.2 We have recently identified a new family of colorimetric chemosensors,3 for which Fe(Hbta)2(H2O)2·2H2O (1) (Hbta = bis(1H-tetrazol-5-yl)amine), able to detect at real time, and with a high selectivity and ultra-sensitivity, 32 different VOCs and HGs, was identified.4 In particular amines, which are detected rather quickly (< 10 min) and with a very high sensitivity. The detection is accompanied by significant and fast colour changes detectable by the naked-eye at ambient conditions. But not only, since the detection can be achieved using simple and intuitive standard chemometric means with a handful smartphone-based analytical method. The crystal lattice of 1 reconstructs after adsorbing VOCs vapours, reconstruction which is accompanied by a spin state and a colour change. In addition to its high thermal stability (up to 175 °C), the colorimetric sensor showed excellent reusability by consecutive cycles of adsorption–desorption. This sensor is low-cost, environmentally friendly, easy to use, and shows excellent and fast detection performances. Such features offer attractive prospects for 1 which could be used for in-field detection and food safety control in environmental conditions. We recently extended this material to new materials showing improved performances,4-6 which I will review in this talk