pH-Stable Zn(II) Coordination Polymer as a Multiresponsive Turn-On and Turn-Off Fluorescent Sensor for Aqueous Medium Detection of Al(III) and Cr(VI) Oxo-Anions

Abstract

Nowadays, coordination polymers (CPs) are promising candidates as sensory materials for their high sensitivity, improved selectivity, fast responsive nature, as well as good recyclability. However, poor chemical stability often makes their practical usage limited. Herein, employing a mixed ligand approach, we constructed a chemically robust CP, {[Zn2L2(DPA)2]·3H2O} n (IITKGP-70, IITKGP stands for the Indian Institute of Technology Kharagpur), which exhibited excellent framework robustness not only in water but also over a broad range of pH solutions (pH = 3–11). The developed framework displayed high selectivity and sensitivity for the detection of trivalent Al3+ ions and toxic hexavalent Cr(VI)-oxo anions in an aqueous medium. The developed framework exhibited an aqueous medium Al3+ turn-on phenomenon with a limit of detection (LOD) value of 1.29 μM, whereas a turn-off effect was observed for toxic oxo-anions (Cr2O7 2– and CrO4 2–) having LOD values of 0.27 and 0.71 μM, respectively. Both turn-on and turn-off mechanisms are speculated via spectroscopic methods coupled with several ex situ studies. Such a multiresponsive nature (both turn-on and turn-off) for aqueous medium detection of targeted cations and anions simultaneously in a single platform coupled with high robustness, ease of scalability, recyclability, and fast-responsive nature makes IITKGP-70 highly fascinating as a sensory material for real-world applications.

Flexible Hexacarboxylate-Based Cobalt Metal–Organic Framework for the Turn-On/Off Detection of Cr3+, Al3+, Fe3+, and Phenylglyoxylic Acid

“…On the other hand, trivalent metal ions, including Al 3+ , Cr 3+ , and Fe 3+ , are some of the serious environmental contaminants due to their high toxicity . An excessive intake of Al 3+ might cause Alzheimer’s disease, Parkinson’s disease, and even breast cancer; Cr 3+ imbalance could cause diabetes and even malignant cells; the imbalance of Fe 3+ in the body might induce the occurrence of anemia, declining immunity, and heart diseases. − Thus, the efficient detection of specific environmental contaminants is urgently required but also challenging. Fortunately, amidst various detection methods, − fluorescent sensors built with metal–organic framework (MOF) materials have distinguished themselves due to their exceptional efficiency, sensitivity, recyclability, and advantageous features. , …”

Selective Detection of Primary Aromatic Amines through Enhanced Luminescence of a 2D + 2D Inclined Polycatenated Microporous Nitro-Functionalized Metal–Organic Framework

“…In this era of polymers, not only that the uses of amines have been extensively increased in the domain of polymers and textile manufacturing, but also they have been significantly used in other growing industries like pharmaceutical, chemical and fertilizer, food processing, and military industries. − Specifically, primary aromatic amines (PAAs), such as aniline (AN) and p -phenylenediamine (PPD), are commonly used in manufacturing of rubber and soft polymers, hair dye, and textile dye and in fine chemical and agrochemical industries, all in a similar popularity. , Such a massive use of these aforesaid PAAs increases the risk of human exposure through food and water, which may cause damage to the respiratory and cardiovascular system, bring about intense incendiary granulomas in the living body, affect the central nervous system, and even trigger the growth of cancer cells. − Therefore, the presence of free PAAs with other amines needs to be critically monitored in industrial wastes as well as in agroproducts that needs an extremely selective and responsive identification of PAA contaminants. − A wide range of techniques for determination of PAAs in environmental samples, including spectrometry, GC, GC-MS, HPLC, capillary electrophoresis with amperometric detection, etc., are associated with elaborate and time-consuming pretreatments such as preconcentration and derivatization prior to detection. − In contrast to that, the application of a fluorescent chemosensor for the detection of PAAs is always a smarter option due to its high sensitivity, straightforward operation, and fast response, which are absolutely necessary for real-time monitoring. − In this context, metal–organic framework (MOF)-based chemosensors are studied extensively, but most of them exhibit fluorescence quenching of active materials by interaction with analytes. − Few fluorescent MOF sensors as active materials for fluorescence recognition of PAAs have been developed , so far, but an enhanced fluorescence emission − with different intensity maxima observed with different primary aromatic amines has not yet been reported. Strategically, it is quite difficult to design fluorescent materials for preferential recognition of primary aromatic amines through π electron transfer between the electron-rich conjugated MOF and π* of electron-rich amines.…”

Regulating water decontamination and food safety by a reusable, nano-sized MOF@cotton@chitosan composite through nanomolar detection of the drug nitroxinil and organoarsenic feed additive p-arsanilic acid

“…40,41 Electronic communications between the metal ions and organic ligand make MOFs potential fluorophores for sensing of various anions, metal ions, biomolecules, hazardous gas molecules, antibiotics, etc. 40,42–45 For sensing purposes, MOF materials have proved themselves as the most suitable sensing probes for different types of molecules due to their structural diversity and stability in aqueous medium, as well as in various solvents. 46 Hence, we synthesized a Hf-based nano-sized MOF using 2-formamido benzene-1,4-dicarboxylic acid (H 2 BDC-NH-CHO) ligand.…”