1 research outputs found
Diffusion-Controlled Detection of Trinitrotoluene: Interior Nanoporous Structure and Low Highest Occupied Molecular Orbital Level of Building Blocks Enhance Selectivity and Sensitivity
Development of simple, cost-effective, and sensitive
fluorescence-based
sensors for explosives implies broad applications in homeland security,
military operations, and environmental and industrial safety control.
However, the reported fluorescence sensory materials (e.g., polymers)
usually respond to a class of analytes (e.g., nitroaromatics), rather
than a single specific target. Hence, the selective detection of trace
amounts of trinitrotoluene (TNT) still remains a big challenge for
fluorescence-based sensors. Here we report the selective detection
of TNT vapor using the nanoporous fibers fabricated by self-assembly
of carbazole-based macrocyclic molecules. The nanoporosity allows
for time-dependent diffusion of TNT molecules inside the material,
resulting in further fluorescence quenching of the material after
removal from the TNT vapor
source. Under the same testing conditions, other common nitroaromatic
explosives and oxidizing reagents did not demonstrate this postexposure
fluorescence quenching; rather, a recovery of fluorescence was observed.
The postexposure fluorescence quenching as well as the sensitivity
is further enhanced by lowering the highest occupied molecular orbital
(HOMO) level of the nanofiber building blocks. This in turn reduces
the affinity for oxygen, thus allocating more interaction sites for
TNT. Our results present a simple and novel way to achieve detection
selectivity for TNT by creating nanoporosity and tuning molecular
electronic structure, which when combined may be applied to other
fluorescence sensor materials for selective detection of vapor analytes