Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real‐Time Sensing

Ali, M. A.; Shoaee, Safa; Fan, Sheng-Qiang; Burn, Paul L.; Gentle, Ian R.; Meredith, Paul; Shaw, Paul E.

doi:10.1002/cphc.201600767

Cited by 18 publications

(17 citation statements)

References 25 publications

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“…Alongside this, diffusion of the nerve agent analyte in the sensing films is another critical factor influencing the detection performance. Studies on the fluorescence quenching–based detection of nitro‐containing explosive vapors using organic fluorophores have shown that analyte diffusion is a first order parameter . The diffusion of nerve agents or simulants into sensing films has not been reported.…”

Section: Analyte Diffusion In Solid‐state Sensing Filmsmentioning

confidence: 99%

“…However, whether the success of the approach is due to favorable analyte diffusion and/or fast reaction between the sensing material and the analyte is as yet unclear. To clarify this question, further investigation on the analyte diffusion using specific measurements is necessary, e.g., by quartz crystal microbalance measurements …”

Section: Analyte Diffusion In Solid‐state Sensing Filmsmentioning

confidence: 99%

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Challenges in Fluorescence Detection of Chemical Warfare Agent Vapors Using Solid‐State Films

et al. 2019

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Organophosphorus (OP)‐based nerve agents are extremely toxic and potent acetylcholinesterase inhibitors and recent attacks involving nerve agents highlight the need for fast detection and intervention. Fluorescence‐based detection, where the sensing material undergoes a chemical reaction with the agent causing a measurable change in the luminescence, is one method for sensing and identifying nerve agents. Most studies use the simulants diethylchlorophosphate and di‐iso‐propylfluorophosphate to evaluate the performance of sensors due to their reduced toxicity relative to OP nerve agents. While detection of nerve agent simulants in solution is relatively widely reported, there are fewer reports on vapor detection using solid‐state sensors. Herein, progress in organic semiconductor sensing materials developed for solid‐state detection of OP‐based nerve agent vapors is reviewed. The effect of acid impurities arising from the hydrolysis of simulants and nerve agents on the efficacy and selectivity of the reported sensing materials is also discussed. Indeed, in some cases it is unclear whether it is the simulant that is detected or the acid hydrolysis products. Finally, it is highlighted that while analyte diffusion into the sensing film is critical in the design of fast, responsive sensing systems, it is an area that is currently not well studied.

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Section: Analyte Diffusion In Solid‐state Sensing Filmsmentioning

confidence: 99%

Section: Analyte Diffusion In Solid‐state Sensing Filmsmentioning

confidence: 99%

Challenges in Fluorescence Detection of Chemical Warfare Agent Vapors Using Solid‐State Films

et al. 2019

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“…A large panel of analytical techniques going from expensive and sophisticated instrumentations to low-cost portable detectors is currently available for this purpose. Of particular interest, fluorescent vapor-phase sensors have been extensively developed [1][2][3][4][5][6] in concomitance with the emergence of a huge variety of fluorescent sensing materials such as conjugated organic/inorganic polymers 2,7 , dendrimers [8][9][10] , molecular imprinted polymers 11 , supramolecular 3D-architectures 12 . Small fluorescent molecules 1 are also attractive since they constitute relevant building block motifs for self-assembly thin-film sensors.…”

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confidence: 99%

Porosity-driven large amplitude dynamics for nitroaromatic sensing with fluorescent films of alternating D–π–A molecules

et al. 2019

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“…Recent studies have indicated that long range exciton diffusion is not occurring in these materials and that the magnitude of the fluorescence quenching response is primarily determined by the analyte diffusion process. 19 PPVs are also prone to aggregation-induced quenching in the solid state, 6 hence similar methods have been employed to prevent losses to the PLQY. Shown in Figure 1.8 are three PPVs, two of which incorporate bulky phenyl substituents to prevent self-quenching by π-stacking interactions.…”

Section: Linear Conjugated Polymersmentioning

confidence: 99%

“…In particular, it was shown that the high sensitivity of so-called amplifying fluorescent polymers is not due to long range exciton diffusion, but the relatively high analyte concentration in the diffusion front that moves through the sensing film as the analyte is sorbed. 19 To quantify the amount of analyte the poly(dendrimer) films can accommodate and the distribution of the analyte within the film, neutron reflectometry was performed. This technique has been successful in showing that:…”

Section: Quantifying Analyte Vapour Uptake and Distribution In Thin Fmentioning

confidence: 99%

Poly(dendrimer)s for explosives sensing

Hutchinson¹

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Trace detection of explosives and explosive related compounds is crucial to countering terrorism and providing homeland security. There are a variety of technologies for this purpose, including ion mobility spectrometry (IMS), mass spectrometry, colourimetric detectors, electrochemical sensing, and surface acoustic wave (SAW) devices. However, the best way to detect explosives is to use a stand-off detection method. One method of achieving this goal is to use a luminescence quenching based system to detect explosive vapours. An example of this type of system is FIDO ® , a small, lightweight handheld device. FIDO ® uses luminescent conjugated polymers but the detection materials used are not very selective and can give rise to false positives. More recently Arborescent2 Ltd has developed Arbsense, which is similar to FIDO ® , but utilises dendrimers as the sensing material. Arbsense sensing elements that contain triarylamine units have been shown to have good selectivity for nitro-containing explosives and taggants. This thesis investigates poly(dendrimer)s and their corresponding monomers, as new materials for the detection of trace quantities of explosives. The poly(dendrimer) structures consist of conjugated triphenylamine based chromophores linked together by a non-conjugated backbone. The chromophores for these novel compounds are based on the material used in the Arbsense device. Such a structural motif combines the versatile processability of polymeric materials as well as an alternative route to controlling the packing of the luminescent chromophores and thus reducing intermolecular π-π interactions that can cause quenching of the luminescence. Furthermore, the poly(dendrimer) can in principle give rise to a less dense film structure, which would facilitate diffusion of analytes into the sensing film. The synthesis and characterization of the monomers and poly(dendrimer)s is described. The chromophores of the materials have variations in conjugation and surface groups to explore the effects of varying the chromophore structure on sensing performance. Solution-based Stern-Volmer measurements were conducted on the materials to investigate the quenching responses to the nitro-aliphatic taggant DMNB and the nitroaromatic analyte DNT. The steady-state measurements indicated the overall quenching response and it was discovered that there was a general trend for an increase in the solution quenching response observed (for both analytes) when going from the monomer to the poly(dendrimer). Time resolved Stern-Volmer measurements allowed for discrimination between dynamic and static components of the quenching and revealed that for most materials the predominant quenching mechanism was dynamic. The exception to this was the M1/P1 monomer-poly(dendrimer) pair, which had the smallest chromophore. The materials were cast into thin films and solid state quenching measurements were also performed in sub-saturated environments of DMNB and DNT vapours. The solid state measurements were not in direct accordance with solutio...

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Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real‐Time Sensing

Cited by 18 publications

References 25 publications

Challenges in Fluorescence Detection of Chemical Warfare Agent Vapors Using Solid‐State Films

Challenges in Fluorescence Detection of Chemical Warfare Agent Vapors Using Solid‐State Films

Porosity-driven large amplitude dynamics for nitroaromatic sensing with fluorescent films of alternating D–π–A molecules

Poly(dendrimer)s for explosives sensing

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