A fluorescence turn-on mechanism to detect high explosives RDX and PETN.

A fluorescent chemosensor to detect satd. nitramine and nitrate ester explosives was devised based on a photochem. redn. reaction. 10-Methyl-9,10-dihydroacridine (AcrH2) was found to transfer a hydride ion equiv. to the high explosives RDX and PETN upon irradn. at 313 nm in degassed acetonitrile solns. Mechanistic photophys. studies indicate that the photoredn. of RDX proceeds via a two-step electron-hydrogen atom transfer reaction, whereas PETN photoredn. proceeds via a three-step electron-proton-electron transfer sequence. A zinc analog was synthesized and found to display an 80- or 25-fold increase in 480 nm emission intensity upon reaction with RDX or PETN, resp. Moreover, the Zn analog was found to be unresponsive to TNT and other common contaminants, in addn. to being photostable under ambient conditions. On the basis of these characteristics, a powerful chemosensor that displays a direct fluorescent response to either RDX or PETN is reported. [on SciFinder(R)]