Fluorescent Gelators for Detection of Explosives

Abstract

Abstract Carbazole-, quinoline-, benzothiazole-, and stilbene-containing fluorescent gelators are synthesized by connecting gelation-driving segments, and their gelation abilities are studied with 13 solvents. Fibrous thin-layer films are prepared on quartz plates from the solutions or gels, and they are studied as chemosensors for explosives. Fluorescence quenching of the films upon exposure to saturated TNT or RDX vapor is used to evaluate the abilities of the films to detect explosives. The relationship between the thickness of the thin-layer film and the quenching efficiency upon exposure to TNT is studied. The morphologies of the thin-layer films are observed by dynamic force mode scanning probe microscopy and discussed with regard to their fluorescence quenching. The interactions among chromophores in the gels, thin-layer films, and solutions are studied by variable-temperature spectroscopy. The mechanism of TNT detection is discussed from the viewpoint of the HOMO and LUMO energy levels.