Dual-Mode Multiple Ion Sensing via Analyte-Specific Modulation of Keto–Enol Tautomerization of an ESIPT Active Pyrene Derivative: Experimental Findings and Computational Rationalization

Abstract

A pyrene-based e xcited - state intramolecular proton transfer (ESIPT) active probe PMHMP was synthesized, characterized, and employed for the ppb-level, dual-mode, and high-fidelity detection of Cu2+ (LOD: 7.8 ppb) and Zn2+ ions (LOD: 4.2 ppb) in acetonitrile medium. The colorless solution of PMHMP turned yellow upon the addition of Cu2+, suggesting its ratiometric, naked-eye sensing. On the contrary, Zn2+ ions displayed concentration-dependent fluorescence rise till a 0.5 mole fraction and subsequent quenching. Mechanistic investigations indicated the formation of a 1:2 exciplex (Zn2+:PMHMP) at a lower concentration of Zn2+, which eventually turned into a more stable 1:1 (Zn2+:PMHMP) complex with an additional amount of Zn2+ ions. However, in both cases, it was observed that the hydroxyl group and the nitrogen atom of the azomethine unit were involved in the metal ion coordination, which eventually altered the ESIPT emission. Furthermore, a green-fluorescent 2:1 PMHMP–Zn2+ complex was developed and additionally employed for the fluorimetric analysis of both Cu2+ and H2PO4 – ions. The Cu2+ ion, owing to its higher binding affinity for PMHMP, could replace the Zn2+ ion from the preformed complex. On the other hand, H2PO4 – formed a tertiary adduct with the Zn2+–complex, leading to a distinguishable optical signal. Furthermore, extensive and organized density functional theory calculations were performed to explore the ESIPT behavior of PMHMP and the geometrical and electronic properties of the metal complexes.

Sequence‐Specific Relay Recognition of Multiple Anions: An Interplay between Proton Donors and Acceptors

“…In addition to the binding energy analysis, analysis of bond length variation has been established as an important parameter to explore such interaction [29] . The changes in the O−H bond distances of HSO 4 − and N−H bond distances for 1 , 1 – 2 HSO 4 − complex, 1 – 2 H + complex and 1 – 2 H + ‐2F − complex were computed theoretically in MeCN to understand the sensing mechanism and presented in Table S2, ESI.…”

“…In addition to the binding energy analysis, analysis of bond length variation has been established as an important parameter to explore such interaction. [29] The changes in the OÀ H bond distances of HSO 4…”

AIE active fluorescent organic nanoparticles based optical detection of Cu2+ ions in pure water: a case of aggregation–disaggregation reversibility

“…[1][2][3][4] Now, among common Cu 2+ ion detection techniques like inductively coupled plasma mass spectroscopy (ICP-MS), 6 atomic absorption spectrometry, 7 inductively coupled plasma atomic emission spectrometry (ICP-AES), 8 anodic stripping voltammetry (ASV), 9 and voltammetry, 10 uorescent detection has shown some additional benets like low-cost and reusable chemosensors, excellent selectivity, sufficient sensitivity, ease of operation, and biocompatible in vivo detection. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Naturally, uorescent detection of Cu 2+ ion in 100% aqueous medium is the need of the hour. Besides, copper plays dual-directional reverse roles with some positive and negative impacts.…”

“…58 Although 1-based FONs were explored earlier, [55][56][57] they were never employed in the selective and sensitive dual-mode detection of Cu 2+ ions in a 100% aqueous medium. As a part of a continuing effort to the develop pyrene-based uorescent chemosensors by our group, [59][60][61][62] herein, we report a pyrene-terpyridine integrated amphiphilic uorescent probe 1 that forms FONs in a pure aqueous medium where those FONs selectively recognized Cu 2+ ions by ratiometric absorption spectral changes and "turn-off" uorescent responses in a 100% aqueous medium. The sensing mechanism has been explored by a systematic DFT study.…”

Biogenic Polymer-Based Fluorescent Assemblies: Versatile Platforms for Ultrasensitive ATP Detection and Enzyme Assay

“…Polymer matrices can shield enclosed dyes from environmental factors like light, moisture, and oxygen, thereby enhancing the stability and shelf life of the sensors . The relatively hydrophobic microenvironment surrounding the dye molecules embedded within the polymer matrix fosters stronger intermolecular interactions with target analytes. , Additionally, the local concentration of dye molecules remains significantly higher than in the bulk solution phase, ensuring multipoint supramolecular interactions that result in enhanced sensitivity. , Furthermore, by reducing background fluorescence and minimizing signal interference, polymer–dye composites can boost the signal-to-noise ratio, leading to more accurate and reliable measurements. Moreover, due to the inherent competitive interactions, these composites can be tailored to respond exclusively to the presence of specific target molecules, thus improving selectivity in sensing applications. , The optical properties of polymer–dye composites, including fluorescence emission wavelengths and quantum yields, can be fine-tuned by selecting different dyes or polymers or by adjusting their relative ratios in the composite. , This adaptability allows for the customization of polymer–dye composite materials to be compatible with a wide range of analytes, making them versatile for various sensing applications.…”