title: Fluorescence and piezoresistive cantilever sensing of trinitrotoluene by an upper-rim tetrabenzimidazole conjugate of calix[4]arene and delineation of the features of the complex by molecular dynamics.
abstract: A new benzimidazole-functionalized calix[4]arene receptor (R) was synthesized and characterized. The receptor R shows better selectivity toward trinitrotoluene (TNT) compared to the other nitro explosives in solution, which also retains its effectiveness for solid-phase detection. The chemical interactions of the molecule with different nitro explosive analytes were studied by fluorescence spectroscopy and by a molecular dynamics approach. The molecular dynamics studies show a 1:3 complex between R and TNT, and hence high sensitivity was imparted by fluorescence studies. The detection of explosive vapors in ambient conditions was tested by using a sensitive coating layer of R on an SU-8/CB-based piezoresistive cantilever surface. The developed device showed large sensitivity toward TNT compared to cyclotrimethylenetrinitramine (RDX) and pentaerythritol tetranitrate (PETN) in the solid state at their respective vapor pressures at room temperature. The detection sensitivity of the device was estimated to be 35 mV for TNT at ambient conditions. Moreover, the sensor does not show a response when exposed to humidity. These results demonstrate that R can be used as one of the coating materials for a cantilever for the detection of TNT using piezoresistivity measurement. R can also detect the explosives in solution with high sensitivity and selectivity by fluorescence spectroscopy.
authors: Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, §Bioinorganic Laboratory, Department of Chemistry, and ⊥Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay , Powai, Mumbai 400076, India.
authors: Manoj
authors: M
authors: Kandpal
authors: Anil Kumar
authors: AK
authors: Bandela
authors: Vijaya Kumar
authors: VK
authors: Hinge
authors: V Ramgopal
authors: VR
authors: Rao
authors: Chebrolu Pulla
authors: CP
authors: Rao
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D047250:Calixarenes / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry; D053834:Explosive Agents / Q000032:analysis*; D056004:Molecular Dynamics Simulation; D049329:Nanostructures / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013499:Surface Properties; D013696:Temperature; D014303:Trinitrotoluene / Q000032:analysis*
chemical_list: D001562:Benzimidazoles; D004852:Epoxy Compounds; D053834:Explosive Agents; D010636:Phenols; D011108:Polymers; C520895:SU-8 compound; C121325:calix(4)arene; D014303:Trinitrotoluene; D047250:Calixarenes; C031000:benzimidazole