Acetate ion augmented fluorescence sensing of Zn²⁺ by Salen‐based probe, AIE character, and application for picric acid detection

Abstract

Counter anion-triggered metal ion detection has been rarely reported by fluorimetric method. To address this challenging issue, a fluorescent probe (H 2 L) has been synthesized from bromo-salicylaldehyde and hydrazine hydrate, and structurally characterized by single crystal X-ray diffraction. The probe shows very weak fluorescence itself.However, its emission intensity increases in the presence of Zn 2+ over other metal ions. Surprisingly, the emission profile of this probe in presence of Zn 2+ is augmented only when acetate anion (OAcŕ) is present as counter anion, that allows for precise quantitative analysis by spectroscopic studies. The compositions and complexation among the probe, Zn 2+ ion, and OAcŕ are supported by ESI-MS, 1 H-NMR, and Job's plot. Based on these studies, it is confirmed that the binding ratio between probe: metal is 1:2 and the detection limit (LOD) for the Zn 2+ is 2.18 μM. The probe is capable of recognizing Zn 2+ ion in the wide range of pH∼6.5-9.5, and it could be efficiently recycled by EDTA. Furthermore, the combinatorial molecular logic gate and memory device have been constructed from the fluorescent behavior of H 2 L with Zn 2+ , OAcŕ, and EDTA input as based on NOT and AND gates. Interestingly, the aggregation-induced emission (AIEE) phenomenon is also perceived with greater than 50% water content in organic water mixtures, which are then useful for the detection of picric acid often used as explosive.

Role of Labile Methanol on the Bio‐inspired Catalytic Activity of a Zn(II)‐based Compound: An Experimental and Theoretical Investigation

“…For compounds 1 and 2 , the K sv value calculated to be 1.015×10 4 M −1 and 1.315×10 4 M −1 , respectively from Stern‐Volmer plot [25] . Figure 12 shows the comparable order for compounds 1; and TNP≫2, 4‐DNP>4 NP>NP>nitro anilines for compound 2 (Figure S19–S22) [23,24] …”

“…[25] Figure 12 shows the comparable order for compounds 1; and TNP @ 2, 4-DNP > 4 NP > NP > nitro anilines for compound 2 (Figure S19-S22). [23,24]…”

Multifunctional Logic Operations Based Upon Congruent Ion Sensing Appended with a Strategic Molecular Device: Spectroscopic Approach

“…Addition of Zn 2+ remarkably enhanced (about 50 times) the fluorescence intensity by maintaining the $${{\lambda }_{em}^{max}}$$ at 425 nm (Figure 1c). [26b] The complexation between TMBP and Zn 2+ was facilitated by the multidentate environment provided to Zn 2+ through the imine−N and methoxy−O donor sites of TMBP. The less twisted and more rigid structure generated through the complexation hindered the radiationless transitions (Scheme 2).…”

“…Previously, some Salen type fluorogenic probes were reported to form complex with Zn 2+ via acetate bridging, which brought greater rigidity and enhanced the emission efficiency (Scheme 2). [26b,29–30] …”

Hydrogen bond directed high-fidelity optical detection of picric acid: A single driver on diverse roads towards the same destiny

“…11) was efficiently involved in the 'turn-off' fluorescence detection of PA in aqueous-MeCN (7 : 3; v/v) medium. 99 Also, a paper-strip based portable kit was developed for the on-site instant recognition of PA.…”