Mechanistic Insight into Selective Sensing of Hazardous Hg²⁺ and Explosive Picric Acid by Using a Pyrene‐Azine‐Hydroxyquinoline Framework in Differential Media

Abstract

A pyrene-hydroxyquinoline tethered ingeniously designed and developed azine based Schiff base luminophoric system, 2-((Z)-((E)-(pyren-1-ylmethylene)hydrazono)methyl)quinolin-8-ol (PHQ) has been explored as a selective 'TURN ON' chromofluorogenic sensor for hazardous Hg 2 + ions in ethanol/H 2 O (9 : 1,v/v) medium with detection limit of 0.22 μM and binding constant of 1.09 x 10 3 M À 1. The detail scrutiny of mechanism of interaction between PHQ and Hg 2 + is rationalized through various techniques like 1 H NMR titration, FT-IR, mass spectral analysis, theoretical computations, Job's plot, dynamic light scattering (DLS), transmission electron microscopy (TEM), time resolved excited state decay dynamics and fluorescence reversibility studies, which concretely declare a synergistic effect of supramolecular aggregation induced enhanced emission and deactivation of photo-induced electron transfer (PET) processes. On the other hand, a 'TURN OFF' luminescence feature of highly fluorescent PHQ hydrosol is utilized for the selective screening of powerful explosive picric acid (PA) in aqueous medium and mechanism is deciphered by means of steady state, time-resolved emission as well as computational studies which altogether reflect a combined effect of PET and ground state complexation between probe and PA. The commendable detection limit of 55 nM and Stern-Volmer quenching constant of 1.48 x 10 4 M À 1 with high quenching efficiency of 84% increases the pertinency of the nano-probe.

Benzo‐γ‐pyrone‐based diorganotin (IV) chelates as fluorescent probes for the detection of picric acid from soil and aqueous samples

“…Most of these are turn‐off sensing probes [ 7,9,14,25,26,48 ] and have not been applied to analyze PA from environmental samples. [ 5,27 ] The probe 10 has been tested in water and soil samples but its limit of detection is almost double than the present method. Moreover, it is based upon the usage of gold nanoparticles, which is very expensive for day to day real applications.…”

Fusing rigid planar units to engineer twisting molecules as dual-state emitters

“…S15 (ESI †) show that the LUMO energy of PA (À3.9 eV) lies between the HOMO and LUMO energies of the probes, which gives access to the electron transfer from the LUMO of NIBBCZ or NIFBCZ in the excited state to that of PA, thereby quenching the luminescence. [54][55][56] Therefore, the PET process from the electron-rich probe to the electron-deficient PA is considered the primary reason for the emission quenching.…”

Mercury Toxicity and Detection Using Chromo-Fluorogenic Chemosensors

“…Sensor 63 showed LOD of 14.7 nM, and capable to quantify Hg 2+ concentration in real water samples. Tapashree et al [ 92 ] reported a pyrene-hydroxyquinoline conjugated azine based Schiff base 64 ( Figure 21 ) for the selective detection of Hg 2+ in ethanol-H 2 O (9:1 v / v ) medium. The absorption bands of 64 at 240 and 290 nm were enhanced with the appearance of a new band at 450 nm upon addition of Hg 2+ .…”