Aggregation Induced Emission Enhancement in Ionic Self-Assembled Aggregates of Benzimidazolium Based Cyclophane and Sodium Dodecylbenzenesulfonate

Cyclophane <b>BIMCP-1</b> undergoes ionic self-assembly with surfactant sodium dodecylbenzenesulfonate (SDBS) at a concentration far below its CMC value to form aggregates with spherical morphology. The rotational restriction of rings in these aggregates facilitates 32-fold enhancement in emission intensity (AIEE) to allow fluorescence based determination of SDBS with 4 μM (1.4 ppm) as the lowest detection limit. Sodium salts of fatty acids and inorganic anions halides, CN^–, HSO₄^–, SO₄^2–, H₂PO₄^–, SCN^–, and NO₃^– do not interfere in the estimation of SDBS

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

1-(<i>p</i>-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/cm² PA