In recent years, much attention has been focused on the efficient detection of chemical pollutants, especially volatile organic compounds (VOCs) and hazardous gases (HGs), using various e-sensors. Such toxic molecules emitted in urban environments are threatening the quality of our daily life. In particular, the detection of relatively small volatile molecules at room temperature, is difficult at low concentration levels, and therefore highly sensitive sensors, preferably produced at low cost, are needed. Our laboratory has recently developed a series of iron coordination complexes that were tested as detectors of toxic industrial chemicals. For example, the mononuclear complex Fe(Hbta)2(H2O)2·2H2O (1) (Hbta = bis(1H-tetrazol-5-yl)amine), was shown to be able to detect in less than 10 min, with a high selectivity and ultra-sensitivity, 32 different VOCs and HGs 1. The detection is accompanied by significant and fast colour changes detectable by simple standard chemometric means using a handful smartphone-based analytical method. The crystal lattice of this material reconstructs after adsorbing VOCs vapours, reconstruction which is accompanied by a spin state and a colour change, which was tracked by several physical methods. 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 to use this material and others 2-3, for in-field detection and food safety control in environmental conditions.
Garcia et al. (Wed,) studied this question.