Ultratrace Detection of Nitroaromatics: Picric Acid Responsive Aggregation/Disaggregation of Self-Assembled p-Terphenylbenzimidazolium-Based Molecular Baskets

Abstract

1-(p-Terphenyl)-benzimidazolium (TRIPOD-TP) molecules undergo self-assembly to form rodlike structures in aqueous medium, as shown by field-emission scanning electron microscopy, transmission electron microscopy, and dynamic light scattering studies. Upon gradual addition of picric acid (PA), these aggregates undergo an aggregation/disaggregation process to complex morphological structures (10(-12)-10(-10) M PA) and spherical aggregates (10(-9)-10(-8) M PA). These spherical aggregates undergo further dissolution to well-dispersed spheres between 10(-7)-10(-6) M PA. During fluorescence studies, these aggregates demonstrate superamplified fluorescence quenching (>97%) in the presence of 10(-5) to 0.2 equiv of the probe concentration, an unprecedented process with PA. The lowest detection limits by solution of TRIPOD-TP are 5 × 10(-13) PA, 50 × 10(-12) M 2,4-dinitrophenol, 200 × 10(-12) M 2,4,6-trinitrotoluene, and 1 nM 1-chloro-2,4-dinitrobenzene. Paper strips dipped in the solution of TRIPOD-TP demonstrate quantitative fluorescence quenching between 10(-17) and 10(-6) M PA using front-surface steady state studies and can measure as low as 2.29 × 10(-20) g/cm(2) PA.

Protonation- and electrostatic-interaction-based fluorescence probes for the selective detection of picric acid (2,4,6-trinitrophenol) – an explosive material

“…Further, the detection of vapor of picric acid by fluorescent probe can give advantage for the device formation. However, only in a couple of cases, thin films 108,109,111,120 of probe undergo fluorescence quenching with picric acid within couple of minutes and in other cases the probe deposited on TLC plate 53,89 or the solution of probe in THF-water 33 detect picric acid vapor.…”

“…The probe 109 coated paper strips detected 137 ag cm -2 PA in solution. The paper strips of 109 could also detect vapor of PA in 120s.Another tripod 111109 (chart 13) with extended hydrophobic pseudo-cavity due to the presence of triphenylene moiety in comparison to biphenyl in 108, could detect 5x10 -13 M PA in water (2% DMSO) and 2.29 × 10 −20 g/cm 2 PA by using 111 coated paper strips. The molecules of 111 self-assembled to form rod like morphology in aqueous medium, as observed through field-emission SEM, TEM and dynamic light scattering studies.…”

Triarylamine‐Cored Dendritic Molecular Gel for Efficient Colorometric, Fluorometric, and Impedometeric Detection of Picric Acid

“…Thus, it is very important to effectively monitor and detect PA for social and environmental safety. Recently, different substrates were developed in this regard, such as metal–organic frameworks, polymers, nanomaterials, quantum dots, and carbon dots, though the use of supramolecular gels or self‐assembled materials is still very limited …”

A Hydrogen‐Bond‐Assisted CHEF Approach for Colorimetric and Fluorescence Recognition of Picric Acid and Its Solid‐Phase Extraction by an Immobilized Probe

“…Available reports on selective sensors for PA generally suffer from several limitations, viz . quenching mechanism, low association constant and detection limit . Several PA selective probes function via Inter‐molecular charge transfer (ICT) process involving ”on‐off“ process .…”