A novel strategy for the synthesis of samarium/europium-metal organic frameworks, and their utilization for detection of Cr3+, Pb2+, and acetone as a luminescent sensor with superior selectivity and sensitivity properties

With outstanding detection selectivity and sensitivity characteristics, samarium/europium-metal organic frameworks (Sm/Eu-MOF) is capable of functioning as a versatile light-emitting sensor particularly for detecting acetone, Cr3+, and Pb2+ in aqueous environment. While considering maximum detectable concentrations of 0.85 μM, 0.46 μM, and 1.04 μM, respectively, competitive energy interactions for acetone, absorption of energy for Cr3+, and substitution of ions for Pb2+ are the elucidated mechanisms of detecting these substances by Sm/Eu-MOF. Successful formulation and synthesis of a core-shell structured Sm/Eu-MOF, which has endurance to acid/alkali conditions and hydration/heat-stability, can be accomplished by utilizing Samarium and Europium nitrate ions, terephthalic acid, and 2, 5-furandicarboxylic acid. The recovery rate of acetone, Cr3+, and Pb2+ detection from real samples were 95.0-101.0 %, 99.8-101.0 %, and 99.9-104.0 %, respectively.

Acridino-Diaza-20-Crown-6 Ethers: New Macrocyclic Hosts for Optochemical Metal Ion Sensing

Acridino-diaza-20-crown-6 ether derivatives as new turn-on type fluorescent chemosensors with an excellent functionality and photophysical properties have been designed and synthesized for metal ion-selective optochemical sensing applications. Spectroscopic studies revealed that in an acetonitrile-based semi-aqueous medium, the sensor molecules exhibited a remarkable fluorescence enhancement with high sensitivity only toward Zn2+, Al3+ and Bi3+, among 23 different metal ions. Studies on complexation showed a great coordinating ability of logK > 4.7 with a 1:1 complex stoichiometry in each case. The detection limits were found to be from 59 nM to micromoles. The new ionophores enabled an optical response without being affected either by the pH in the range of 5.5-7.5, or the presence of various anions or competing metal ions. Varying the N-substituents of the new host-backbone provides diverse opportunities in both immobilization and practical applications without influencing the molecular recognition abilities.

Ultratrace Detection of Nickel(II) Ions in Water Samples Using Dimethylglyoxime-Doped GQDs as the Induced Metal Complex Nanoparticles by a Resonance Light Scattering Sensor

This study aimed to synthesize dimethylglyoxime (DMG) (N-source)-doped graphene quantum dots (N-GQDs) via simultaneous pyrolysis of citric acid and 1.0% (w/v) DMG. The maximum excitation wavelength (λmax, ex = 380 nm) of the N-GQD solution (49% quantum yield (QY)) was a red shift with respect to that of bare GQDs (λmax, ex = 365 nm) (46% QY); at the same maximum emission wavelength (λmax, em = 460 nm), their resonance light scattering (RLS) intensity peak was observed at λmax, ex/em = 530/533 nm. FTIR, X-ray photoelectron spectroscopy, XRD, energy-dispersive X-ray spectroscopy, and transmission electron microscopy analyses were performed to examine the synthesized materials. The selective and sensitive detection of Ni2+ using the RLS intensity was performed at 533 nm under the optimum conditions consisting of both 25 mg L-1 N-GQDs and 2.5 mg L-1 DMG in the ammonium buffer solution of pH 9.0. The linearity of Ni2+ was 50.0-200.0 μg L-1 with a regression line, y = 5.031x - 190.4 (r 2 = 0.9948). The limit of detection (LOD) and the limit of quantitation (LOQ) were determined to be 20.0 and 60.0 μg L-1, respectively. The method precision expressed as % RSDs was 4.90 for intraday (n = 3 × 3) and 7.65 for interday (n = 5 × 3). This developed method afforded good recoveries of Ni2+ in a range of 85-108% when spiked with real water samples. Overall, this innovative method illustrated the identification and detection of Ni2+ as a DMG complex with N-GQDs, and the detection was highly sensitive and selective.

Fluorescence Sensors for Bismuth (III) Ion from Pyreno[4,5-d]imidazole Derivatives

Three pyreno[4,5-d]imidazole derivatives are synthesized and evaluated as fluorescent sensors for bismuth (III) ion. The target compounds are prepared in 55-86% yields from a condensation reaction between pyrene-4,5-dione and aromatic aldehydes. The compound bearing a phenolic group can selectively detect bismuth (III) ion via fluorescence enhancement with a detection limit of 1.20 μm in CH₃ CN-DMSO mixture and 3.40 μm in 10% pH5 aqueous in CH₃ CN-DMSO mixture. The sensing mechanism involving a formation of coordination complex is investigated by UV-VIS and fluorescence titrations, ¹ H-NMR and the decomplexation of the bismuth complex by sulfide ion. The application of this sensor for quantitative analysis of spiked bismuth (III) ion in real water samples from two different sources is demonstrated.

An efficient new dual fluorescent pyrene based chemosensor for the detection of bismuth (III) and aluminium (III) ions and its applications in bio-imaging

A new simple pyrene based schiff base chemosensor 1 (nicotinic acid pyren-1-ylmethylene-hydrazide) has been constructed and is prepared from 1-pyrenecarboxaldehyde and nicotinic hydrazide. Notably, the chemosensor 1 exhibited remarkable colour changes while in the presence of trivalent metal ions like Bi³⁺ & Al³⁺ ion in DMSO-H₂O, (1:1 v/v, HEPES = 50 mM, pH = 7.4). The UV-Vis spectral investigation of chemosensor 1 showed that the maximum absorption peak appeared at 378 nm. In emission studies, chemosensor 1 develops weak fluorescence, while upon the addition of Bi³⁺ and Al³⁺ ions, it exhibits an enhancement of fluorescence intensity. Nevertheless, rest of metal ions have no changes in the emission spectra. The association constant of chemosensor 1 for binding to Bi³⁺ & Al³⁺ system had a value of 1.27 × 10⁴ M^-1 and 1.53 × 10⁴ M^-1. The detection limits were 0.12 µM for Bi³⁺ and 0.17 µM for Al³⁺ respectively. The overall results reveal that chemosensor 1 can act as a dual-channel, highly selective, and sensitive probe for Bi³⁺ and Al³⁺ ions. Moreover, the fluorescence imaging of chemosensor 1 was applied in RAW 264.7 cell line and cytotoxicity assay prove that this chemosensor 1 is non-toxic as well as highly biocompatible.

Resonance light scattering sensor of the metal complex nanoparticles using diethyl dithiocarbamate doped graphene quantum dots for highly Pb(II)-sensitive detection in water sample

This study was aimed to detect Pb²⁺ using diethyl dithiocarbamate-doped graphene quantum dots (DDTC-GQDs) based pyrolysis of citric acid. The excitation maximum wavelength (λ_max, ex = 337 nm) of the DDTC-GQDs solution was blue shift from bare GQDs (λ_max, ex = 365 nm), with the same emission maximum wavelength (λ_max, em = 459 nm) indicating differences in the desired N, S matrices decorating in the nanoparticles. Their resonance light scattering intensities were peaked at the same λ_max, ex/em = 551/553 nm without any background effect of both ionic strength and masking agent. Under optimal conditions, the linear range was 1.0-10.0 μg L^-1 (R² = 0.9899), limit of detection was 0.8 μg L^-1 and limit of quantification was 1.5 μg L^-1. The precision, expressed as the relative standard deviations, for intra-day and inter-day analyses was 0.87% and 4.47%, respectively. The recovery study of Pb²⁺ for real water samples was ranged between 80.8% and 109.5%. The proposed method was also proved with certified water sample containing 60 μg L^-1 Pb²⁺ giving an excellent accuracy and was then implied satisfactorily for ultra-trace determination of Pb²⁺ in drinking water and tap water samples.

Hydride generation-resonance Rayleigh scattering and SERS spectral determination of trace Bi

In acidic solutions, Bi(III) was reduced by NaBH4 to form BiH3 gas. Using I3(-)graphene oxide (GO) as absorption solution, the BiH3 gas reacted with I3(-) to form I(-) that resulted in the I3(-) concentration decreasing. In the absence of BiH3, the I3(-) concentration was high, and as receptors it was closed to the surfaces of GO which was as donors. Then the surface plasmon resonance Rayleigh scattering (RRS) energy of GO transfers to I3(-) heavily, and results in the RRS quenching severely. With the increase of the Bi(III) concentration, the receptors and the RRS energy transfer (RRS-ET) decreased, so the RRS intensity enhanced linearly at 370nm. The RRS intensity was linear to the Bi(III) concentration in 0.05-5.5μmol/L, with a detection limit of 4ng/mL Bi. A new RRS-ET spectral method was developed for the determination of trace Bi(III). Using I3(-) as the absorption solution, silver nanorod (AgNR) as sol substrate and Vitoria blue B (VBB) as molecular probe, a SERS method was developed for detection of Bi.