A Ni-MOF as Fluorescent/Electrochemical Dual Probe for Ultrasensitive Detection of Picric Acid from Aqueous Media

Abstract

A water-stable, microporous, luminescent Ni(II)-based metal–organic framework (MOF) (Ni-OBA-Bpy-18) with a 4-c uninodal sql topology was solvothermally synthesized using mixed N-, O-donor-directed π-conjugated co-ligands. The extraordinary performance of this MOF toward rapid monitoring of mutagenic explosive trinitrophenol (TNP) in aqueous and vapor phases by the fluorescence “Turn-off” technique with an ultralow detection limit of 66.43 ppb (K sv: 3.45 × 105 M–1) was governed by a synchronous occurrence of photoinduced electron transfer–resonance energy transfer–intermolecular charge transfer (PET-RET-ICT) and non-covalent π···π weak interactions, as revealed from density functional theory studies. The recyclable nature of the MOF, detection from complex environmental matrices, and fabrication of a handy MOF@cotton-swab detection kit certainly escalated the on-field viability of the probe. Interestingly, the presence of electron-withdrawing TNP decisively facilitated the redox events of the reversible NiIII/II and NiIV/III couples under an applied voltage based on which electrochemical recognition of TNP was realized by the Ni-OBA-Bpy-18 MOF/glassy carbon electrode, with an excellent detection limit of ∼0.6 ppm. Such detection of a specific analyte by MOF-based probe via two divergent yet coherent techniques is unprecedented and yet to be explored in relevant literature.

A Halogen‐Bonded Organic Framework (XOF) Emissive Cocrystal for Acid Vapor and Explosive Sensing, and Iodine Capture

“…Stern–Volmer plot of relative luminescent intensity versus picric acid concentration until 15 µ m afforded a quenching constant ( Ksv ) of 1.33 × 10 5 m −1 and limit of detection (LoD) of 12 n m (Figure S64, Supporting Information), which is on par with the best MOF and COF materials (Table S10, Supporting Information). [ 61,78–82 ] We attribute this remarkable feature to the fluorescent quenching caused by photo induced electron transfer, which is a common mechanism for AIEgen‐based sensors to detect picric acid (Figure S67, Supporting Information). Moreover, TIEPE‐DABCO is available for reversible picric acid sensing upon washing off with ethanol (Figure S65, Supporting Information).…”

Detection of Nitroaromatic and Peroxide-Based Explosives with Amine- and Phosphine-Functionalized Diketopyrrolopyrroles

“…In a world of rapidly evolving global threats and uncertainties, defined by diverse and sophisticated enemy activity and terrorist attacks, innovative approaches to enable the identification of hidden ordnance, improvised explosive devices (IEDs), and landmines command significant importance. − Military-grade nitroaromatic explosives, such as 2,4,6-trinitrotoluene (TNT), and volatile impurities, such as 2,4-dinitrotoluene (DNT), endure as key detection challenges, often present in decommissioned landmines, representing both a homeland security issue and environmental concern. − These materials, and peroxide-based explosives, such as triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), are also widely deployed in IEDs, gaining prominence in recent years because of their emergence as energetic components in a number of high-profile public bombings . Because of their varied chemical and physical properties, broad-class detection of explosives remains a complex problem.…”

“…Fluorescence emission spectra were corrected for the photomultiplier response using the manufacturer's correction method. Fluorescence quantum yields for DPPs (1)−( 5) and (9) were experimentally determined following a previously described method, 40 utilizing an integrating sphere (Labsphere, 6″ inner diameter). Samples were irradiated employing a Xe lamp (λ exc = 469 nm), and the signals were collected by an optical fiber coupled to a Maya2000ProUV-NIR spectrometer.…”

Portable and non-invasive fluorescent thin films from photocatalytically active carbon dots for selective and trace-level detection of picric acid

“…26 Until now, many fluorescent systems have been employed for detecting NACs. The most successful demonstrations of FL detection of PA were focused mainly on graphene QDs, 27 semiconductor QDs, 28 perovskite QDs, 29 fluorescent polymers, 30 metal–organic frameworks, 31,32 chemosensors, 33,34 supramolecular assembly, 35 etc. A very few reports are available with CDs as FL probes for detecting PA, and even they are in the solution phase.…”