Metalloporphyrins as sensing elements for the rapid detection of trace TNT vapor

A series of porphyrin or metalloporphyrin-doped mesostructured silica films were successfully fabricated using small molecular (CTAB) or macromolecular (F127, P123) surfactants as structure-directing agents, and examined for chemosensor applications to detect trace vapors of explosives such as TNT and DNT. All prepared nanocomposite films show high fluorescence quenching sensitivity towards TNT and DNT vapors, but, their performances are strongly dependent on the formed mesostructure, the pore size and the type of sensing elements ( porphyrin units). The cadmium porphyrin film with bicontinuous worm-like mesostructure exhibits the highest quenching efficiency, close to 60% after 10 s of exposure. Besides the superior TNT detecting capability, these hybrid films offer several advantages over other fluorescence-based sensory materials, such as a simple preparation procedure, inexpensive materials as well as the stability of organic sensing elements in an inorganic matrix. These results suggest that these new kinds of mesostructured nanocomposites are potentially useful chemosensory materials for rapidly detecting trace explosives.