Preparation of monolayer-assembled fluorescent film and its sensing performances to hidden nitroaromatic explosives

Pyrene was chemically assembled on a glass plate surface in a monolayer manner via spacers containing triethylenetetramine （TETA） subunits. It has been demonstrated that the fluorescence emission of the film is sensitive to the presence of trace amount of nitroaromatic compound （NAC） vapors. As discovered in the present work, the response selectivity of the pyrene-functionalized film depends on the length of the spacer, the vapor pressure of a given NAC, and the quencher size. The film shows faster response to those quenchers which have higher vapor pressure and smaller size. Compared to the film with shorter spacers, the present film with longer flexible spacers shows a slower response to the NACs, but higher selectivity to the quencher size. Additionally, the detection limits to common ex- plosives in vapor phase, 2,4,6-trinitrotoluene （TNT） and 2,4-dinitrotoluene （DNT）, are 7.14×10^-12 and 5.49×10^-11 g·mL^-1, respectively. Further examinations indicated that the sensing process is fully reversible, and the vapors of those common interference such as benzene, toluene, ethanol, and perfume have little effect upon the sensing performances of the film.