Aqueous phase selective detection of 2,4,6-trinitrophenol using a fluorescent metal–organic framework with a pendant recognition site

Abstract

Prompt and selective detection of nitro explosives in the aqueous phase is in high demand to meet homeland security and environmental concerns. Herein we report the chemically stable porous metal organic framework UiO-68@NH2 with a pendant recognition site for selective detection of the nitro-aromatic explosive TNP in the aqueous phase. The pendant Lewis basic amine moieties are expected to selectively interact with TNP via electrostatic interactions and act as recognition sites for TNP. The MOF can detect the presence of TNP in water at a concentration as low as 0.4 ppm with a response time of a few seconds. In addition, both excitation and emission wavelengths of the MOF are in the visible region. The high selectivity was observed even in the presence of competing nitro analytes in the aqueous phase. The quenching constant for TNP was found to be 5.8 × 10(4) M(-1) which is 23 times higher than that for TNT and for RDX, demonstrating superior and selective quenching ability. This unprecedented selectivity is ascribed to electron-transfer and energy-transfer mechanisms as well as electrostatic interactions between TNP and the MOF. An MOF-coated paper strip that we prepared demonstrated fast and selective response to TNP in water, which represents a first step towards a practical application.

Adenine‐Based Coordination Polymers: Synthesis, Structure, and Properties

“…In this context, it may be worthwhile to note that co‐crystals of TNP with adenine have been isolated, which lends credence to this postulate as the co‐crystals exhibit intermolecular hydrogen bonding (Figure S28). [16b] The energies of the other non‐nitro aromatic analytes such as benzene, toluene, and phenol lie much higher above the LUMO of the ligand, which appears to be in agreement with its non‐quenching behavior (Figure S21).…”

“…However, the energy criteria alone may not explain the high quenching efficiency observed with DNP and NP as their LUMO energies are higher than TNP and are comparable with the other nitro aromatic analytes. Another postulate for the enhanced quenching efficiency with respect to the nitrophenols could be to consider the favorable hydrogen‐bond interactions between the freely accessible amine group of the framework and the hydroxyl group of the nitrophenols . In this context, it may be worthwhile to note that co‐crystals of TNP with adenine have been isolated, which lends credence to this postulate as the co‐crystals exhibit intermolecular hydrogen bonding (Figure S28).…”

Exploitation of Guest Accessible Aliphatic Amine Functionality of a Metal–Organic Framework for Selective Detection of 2,4,6-Trinitrophenol (TNP) in Water

“…These features result in the rational design and study of MOF materials for the desired selective detection of cations, anions, small molecules, explosives and biomolecules. 13,48,80,[86][87][88][89][90][91][92][93][94][95][96][97][98][99] In view of the targeted selective TNP detection in water by MOFs with high sensitivity, regardless of the latest advances, the reports of fluorescent MOFs exhibiting selective and sensitive TNP detection in concurrent presence of other nitro analytes are only few, while most of the reported MOFs involve detection only in organic/ organic-water mixture phase. 86 Subsequent to the discovery of the key role of lewis basic pyridyl functionality behind selective aqueous-media TNP sensing; 88 as a first-of-its kind approach, very recently, our group had come up with two reports of aqueous phase selective TNP-sensing based on two different MOF compounds.…”

A Fluorescent 1,3‐Diaminonaphthalimide Conjugate of Calix[4]arene for Sensitive and Selective Detection of Trinitrophenol: Spectroscopy, Microscopy, and Computational Studies, and Its Applicability using Cellulose Strips

“…[27][28][29][30][31] Althought here are reportsf or the selectiver ecognition of TNP, the receptors with high selectivity and sensitivity are limited and certainly the supramolecular ones,s uch as the calixarenebasedo nes, are scarce. [32][33][34][35][36][37][38][39][40][41][42][43] Calixarenesc an be easily modified on its upper-or lower-rim to meet the requisiten eeds in providing complementary interactings ites with the analyte. [44][45][46][47][48][49][50][51] In addition, the arene cavity of calix platformi sa lso utilized for trapping the guests as reportedb yu sa sw ella so thers.…”