A fluorescence-based cyclodextrin sensor to detect nitroaromatic explosives

We report the use of a cyclodextrin inclusion complex (CIC) in fluorescence sensing to provide a method to classify energetic nitroaromatic compounds. A CIC was prepared by the inclusion of 9,10-bis(phenylethynyl)anthracene (BPEA) with γ-cyclodextrin (CD) (BPEA/CD) in water with 5% tetrahydrofuran by volume. The inclusion behaviour of BPEA with γ-CD was studied by fluorescence spectroscopy. The effect of α- and β-CD with BPEA was also studied. In this system, the inclusion complex BPEA/CD acted as the host and the guests were the explosives 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrophenyl-N-ethylnitramine (Tetryl), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX) and pentaerythritoltetranitrate (PETN). The binding of TNT, RDX, Tetryl, HMX and PETN with CD/BPEA was studied for the potential use of BPEA/CD in a sensing application. Experiments were also conducted with explosives and BPEA in the absence of CD. The optical response found for the explosives TNT, RDX, Tetryl, HMX and PETN with BPEA/CD was modelled with a modified Stern–Volmer relationship. This investigation showed successful classification of aromatic and non-aromatic explosives. The approach using a CD-based fluorescence sensor has the potential to be a sensing technology for the detection of nitroaromatic explosives.