Detection and Distinction
of DNT and TNT with a Fluorescent
Conjugated Polymer Using the Microwave Conductivity Technique
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Abstract
We report the detection and distinction of dinitrotoluene
(DNT)
and trinitrotoluene (TNT) by the microwave conductivity technique
using a cyclopentadithiophene–bithiazole-based polymer (CPDT-BT)
as sensor. Although the conventional fluorescence quenching experiments
showed just “turn OFF” of the polymer fluorescence for
both DNT and TNT, time-resolved microwave conductivity (TRMC) revealed
that the photoconductivity of the polymer, which is “turned
OFF” in the pristine state became “ON” in the
presence of DNT but remained “OFF” with TNT, allowing
easy distinction between them. Moreover, the decay rate of the transient
kinetics was found to be sensitive to the DNT concentration, implementing
a unique method for the determination of unknown DNT concentration.
The observations are discussed in viewpoint of charge separation (CS)
and formation of charge transfer (CT) complex by considering deeper
LUMO of TNT than DNT calculated from the DFT method. This study brings
out a novel technique of speedy detection and distinction of environmentally
important analytes, an alternative to the fluorescence quenching