Using eugenol scaffold to explore the explosive sensing properties of Cd(II)-based coordination polymers: experimental studies and real sample analysis.

Eugenol, the major constituent of clove oil, has been explored as an essential natural ingredient for ages owing to its versatile pharmacological properties. However, to date, the coordination chemistry of eugenol derivatives has not been much explored. In the present work, an eugenol-based Schiff base ligand (HL) was synthesized and structurally confirmed through ESI-MS, NMR, and FT-IR spectroscopy studies. Consequently, the N,O-donor chelating ligand HL was coordinated with Cd2+, in the presence of bridging pseudohalides (thiocyanate, SCN-, and dicyanamide, N(CN)2-) to synthesize two luminescent coordination polymers (CPs 1 and 2): [Cd2(L)2(X)2]n (where HL = 4-allyl-2-(((2-(benzylamino)ethyl) imino)methyl)-6-methoxyphenol and Xs are bridging pseudohalides, i.e., SCN- and N(CN)2-) on a Cd-eugenol scaffold. The CPs depicted structural diversity, bulk-phase purity, thermal stability, and the presence of interlayer supramolecular C-H⋯π interactions together with C-H⋯S (for CP 1) and C-H⋯N (for CP 2) interactions. The CPs further exemplified themselves as selective and sensitive 'turn-off' probes towards trinitrophenol (TNP) (quenching efficiency: 82.02% and 83.86% for 1 and 2) among a pool of hazardous nitroaromatic compounds (NACs). Accordingly, 1 and 2 exhibited an ultralow limit of detection (LOD) of 0.29 and 0.15 µM, with high quenching constants (KSV) of 5.91 × 104 and 17.60 × 104 M-1, respectively. In addition, TNP sensing events were evidenced to be recyclable and exhibited fast response (∼31 s, 1, and ∼40 s, 2), which increased its real-world viability. Vapor phase TNP sensing was also accomplished upon drop-casted CP films. Experimental investigations and theoretical DFT study confirmed the cooperative occurrence of RET-IFE-PET-collisional quenching and non-covalent π⋯π stacking as key factors involved in the TNP sensing performance. The competency of 1 and 2 in the detection of TNP from several complex environmental matrices (CEMs), viz. matchstick powder, river and sewage water, and soil specimens, was also established with good recovery (∼66-86% and ∼68-93% for 1 and 2, respectively) and high KSV values (3.90-11.39 × 104 and 6.17-18.79 × 104 M-1 for 1 and 2, respectively).

Mixed N,O-donor Directed Blue Emissive Nano-dispersed Mesoporous Mn(II)-MOF: Dual Sensing Probe for Recyclable and Ultrasensitive ppb-Level Recognition of TNP and Cr(VI)-Oxoanions.

A new mesoporous Mn(II)-MOF [Mn2(phen)2(nia)2]∞ with 4-c uninodal net topology and reiterating rectangular channels in its cargo-net like extension was synthesized using π-conjugated phenanthroline (phen) and syn-syn bridging 5-nitroisopthalic acid (nia) linkers. The MOF (1) exhibited phase purity, uniform morphology, photo and thermal stability, and robustness; duly triggered by the exceptional framework rigidity via intermolecular H-bonding and interlayer π-π stacking interactions. The bright-blue luminescence of the MOF nano-dispersion was explored for sensitive, specific and ultrafast detection of trinitrophenol (TNP) with extremely low LOD (90.62 nM), high KSV (18.27×104 M-1) and Kq (4×1014 M-1s-1). The vapor-phase TNP sensing was also accomplished. Additionally, 1 served towards discriminatory, aqueous-phase monitoring of Cr(VI)-oxoanions, depicting LODs: 36.08 and 35.70 ppb; KSV: 3.46×104 and 4.87×104 M-1; Kq: 3.26×1013 M-1s-1 and 4.31×1013 M-1s-1; and response time: 32 and 40s for CrO4 2- and Cr2O7 2- respectively. The quenching mechanisms (i. e., RET, PET, IFE, weak interactions, collisional quenching and π⋅⋅⋅π stacking) was explained from several experimental investigations and theoretical DFT calculations. The recyclable sensing events and quantification from complex environmental matrices with admirable recovery rates and high KSV (13.02-22.44×104; ~6.31-10.98×104 and ~6.60-11.42×104 M-1 for TNP, CrO4 2- and Cr2O7 2-) undoubtedly advocated the consistency of the probe.

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

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 (Ksv: 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.

Strategic optimization of phase-selective thermochemically amended terra-firma originating from excavation-squander for geogenic fluoride adsorption: a combined experimental and in silico approach.

An inimitable adsorbent "FI-TM-BWCC," emanated from meta-phase-selective thermochemical modulation of excavation-squander (mine waste)-derived terra-firma (blackish white china clay, i.e., BWCC), is explored in the present work for fluoride (F-) adsorption purpose. FI-TM-BWCC portrayed an excellent adsorption efficiency (95% removal capacity and Qe: 99 mg/g, at initial adsorbate dose: 10 mg/L, pH: 7±0.5, adsorbent dosage: ~600 mg, exposure time: 60 min). At identical experimental conditions, the F- scavenging phenomenon was superior than two analogous adsorbents: (i) biopolymer chitosan and glutaraldehyde cross-linked BWCC (CG@BWCC, wherein F- removal efficiency: 74%) and (ii) meta-phase-selective thermally moduled BWCC (TM-BWCC, removal efficiency: 75%). BWCC predominantly comprises kaolinite and a trace amount of anatase along with prime elemental compositions: 41.71% Al2O3, 49.80 % SiO2, 4.25% Fe2O3, and 3.93% TiO2, as revealed by PXRD and XRF analyses. The thermochemical modulation pathway significantly escalated the BET surface area of BWCC (~11.92 m2/g, avg. pore radius: 23.64 Å, i.e., mesoporous in nature) to FI-TM-BWCC (216.95 m2/g, avg. pore radius: 31.41 Å). The fluoride-adsorbed F-•••FI-TM-BWCC species revealed a reduced surface area of 21.5 m2/g, which was explained in the light of ion exchange pathway on FI-TM-BWCC's non-uniform surface (surface roughness/SA of 1597 nm, reduced to 1179 nm after F- uptake). The spontaneous F-•••FI-TM-BWCC interaction (ΔG0 = -6.25 kJ) occurred following chemisorption-controlled ion exchange (CCIE) pathway as appearance of a F1s band at 685.5 eV was rationalized for Si-F bond formation; corroborating pseudo second-order (PSO) kinetics and resembling Freundlich isotherm. The usefulness of FI-TM-BWCC was diversified through field validation with natural groundwater specimens and proposition of a gravity-fed defluoridation unit. The flow rate was documented to be ~11 liters per hour (LPH) by implementing viscous turbulence fluent model. The experimental findings certainly followed the premise conventions of sustainability metrics upholding socio-economic equipoise.

Unveiling of a smartphone-mediated ratiometric chemosensor towards the nanomolar level detection of lethal CN-: combined experimental and theoretical validation with the proposition of a molecular logic circuitry.

A promising naphthalene-functionalized ratiometric chemosensor (E)-1-((naphthalen-5-yl) methylene)-2-(2,4-dinitrophenyl) hydrazine (DNMH) is unveiled in the present work. DNMH demonstrates brisk discernible colorimetric response from yellow to red in the presence of CN-, a lethal environmental contaminant, in a near-perfect aqueous medium with a LOD of 278 nM. The "key role marker" controlling the electrochemical and non-covalent H-bonding interaction between DNMH and CN- is through the commendable role of acidic -NH functionalities. Kinetic studies reveal a pseudo second order reaction rate and the formation of an unprecedented photostable adduct. The negative value of ΔG as evaluated from ITC substantiates the spontaneity of the DNMH⋯CN- interaction. The sensing mechanism was further reinforced with state-of-the-art theoretical investigations, namely DFT, TDDFT and Fukui indices (FIs). Moreover, the proposition of a reversible multi-component logic circuitry implementing Boolean functions in molecular electronics has also been triggered by the turn-over spectrophotometric response of the ditopic ions CN- and Cd2+. The cytotoxicity of DNMH towards Bacillus thuringiensis and Escherichia coli is successfully investigated via the MTT assay. Impressively, "dip stick" and "easy to prepare" test paper device and silica gel-based solid-phase CN- recognition validate the on-site analytical application of DNMH. Furthermore, the involvement of a synergistic approach between 'chemistry beyond the molecule' and 'engineering' via an exquisitely implemented smartphone-assisted colorimetric sensory prototype makes this work unprecedented among its congeners and introduces a new frontier in multitudinous material-based functional product development.

Amine-substituent induced highly selective and rapid "turn-on" detection of carcinogenic 1,4-dioxane from purely aqueous and vapour phase with novel post-synthetically modified d10-MOFs.

Herein, an amine decorated Cd(II) metal-organic framework (MOF) with a uninodal 6-c topology was synthesized as a suitable platform for facile post-synthetic modification (PSM). The as-synthesized parent d10-MOF (1) with free -NH2 centers, when functionalized with two different carbonyl substituents (1-naphthaldehyde and benzophenone) of varying conjugation, produces two novel luminescent MOFs (LMOFs) viz.PSM-1 and PSM-2. The judicious incorporation of carbonyl substituents into the skeleton of 1 was rationalized via ESI-MS, 1H-NMR, FT-IR and PXRD analyses. Interestingly, both PSM-1 and PSM-2 show 'turn-on' luminescent behaviour in the presence of 1,4-dioxane with the limit of detection (LOD) as 1.079 ppm and 2.487 ppm, respectively, with prompt response time (∼55 s & ∼58 s, respectively). The inhibition of PET is comprehended to be the prime reason for luminescence enhancement upon interaction with the targeted analyte which was further validated from DFT calculations. In continuation, the PSM-MOFs were equally responsive towards 1,4-dioxane in several complex environmental matrices and cosmetic products. Additionally, vapor phase detection of 1,4-dioxane using PSM-MOFs has also been demonstrated as an additional advantage ensuring propagation of future research endeavour.

Advancement in functionalized luminescent frameworks and their prospective applications as inkjet-printed sensors and anti-counterfeit materials.

Supramolecular luminescent frameworks with conjugated architectures exhibits interesting photophysical properties with phenomenal chemical and thermal stability. This has instigated global researchers towards its extensive application in toxic analyte detection and the formulation of anti-counterfeit materials. In correlation with this present scenario, luminescent metal-organic frameworks (LMOFs), possessing tailorable structural and functional properties and exceptional physicochemical features, have been categorized as emerging 'smart materials'. Interestingly, LMOFs have assisted in the rapid development of an effectual sensing platform and swift fabrication of anti-counterfeit materials on desirable substrates with the aid of 'Inkjet Printing', which is a viable, low-cost, and high-resolution technology. Inkjet printing is an excellent material deposition technique in the modern era owing to its easy settling over flexible substrates, simplistic emergence of large area image patterns with improved throughput, minimal cost, explicit resolution, and least waste generation. The present review provides state-of-the-art progress on LMOFs based (i) luminescent security ink fabrication with static and dynamic multinodal luminescent materials and (ii) sensory device formulation for the easy and instantaneous recognition of hazardous analytes through the 'Inkjet Printing' technology. This techno-chemical integration will be certainly beneficial to prevent the growth of counterfeit materials and monitor the bioaccumulation of hazardous analytes in our ecological system.