title: Detection of nitroaromatic explosives based on photoluminescent polymers containing metalloles.
abstract: The synthesis, spectroscopic characterization, and fluorescence quenching efficiency of polymers and copolymers containing tetraphenylsilole or tetraphenylgermole with Si-Si, Ge-Ge, and Si-Ge backbones are reported. Poly(tetraphenyl)germole, 2, was synthesized from the reduction of dichloro(tetraphenyl)germole with 2 equivs of Li. Silole-germole alternating copolymer 3 was synthesized by coupling dilithium salts of tetraphenylsilole dianion with dichloro(tetraphenyl)germole. Other tetraphenylmetallole-silane copolymers, 4-12, were synthesized through the Wurtz-type coupling of the dilithium salts of the tetraphenylmetallole dianion and corresponding dichloro(dialkyl)silanes. The molecular weights (M(w)) of these metallole-silane copolymers are in the range of 4000 approximately 6000. Detection of nitroaromatic molecules, such as nitrobenzene (NB), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and picric acid (PA), has been explored. A linear Stern-Volmer relationship was observed for the first three analytes, but not for picric acid. Fluorescence spectra of polymetalloles or metallole-silane copolymers obtained in either toluene solutions or thin polymer films displayed no shift in the maximum of the emission wavelength. This suggests that the polymetalloles or metallole-silanes exhibit neither pi-stacking of polymer chains nor excimer formation. Fluorescence lifetimes of polymetalloles and metallole-silanes were measured both in the presence and absence of TNT, and tau(o)/tau is invariant. This requires that photoluminescence quenching occurs by a static mechanism.
authors.affiliation: Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, 92093-0358, USA.
authors.forename: Honglae
authors.initials: H
authors.lastname: Sohn
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sailor
authors.forename: Douglas
authors.initials: D
authors.lastname: Magde
authors.forename: William C
authors.initials: WC
authors.lastname: Trogler