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Many common explosives are mostly composed of nitro-compounds. Picric acid (PA) has emerged as a potential alternative due to its great explosive capability. Moreover, PA is also a serious groundwater contaminant due to its high-water solubility. As a result, the development of advanced sensors and catalysts to enable the precise detection and elimination of PA in water and food samples is critical for public health and the environment. In the present investigation, we developed NaxLiyPr(MoO4)2:Tb3+@Arg and NaxLiyPr(WO4)2:Tb3+@Arg (x = 10 mmol and y = 5 mmol) via a hydrothermal process and established their potency for photoluminescence (PL) detection and photocatalytic degradation of PA. The characterization of the produced nanoparticles was done by various techniques. The PL characteristics of NaxLiyPr(MoO4)2:Tb3+@Arg show that it is highly sensitive and selectively detects PA in an aqueous medium. The predominant emission band at 545 nm exhibited a distinguished quenching with the introduction of PA solution in the colloidal solution of the prepared nanomaterials. The NaxLiyPr(MoO4)2:Tb3+@Arg demonstrated exceptional selectivity and sensitivity against PA, with a limit of detection (LOD) of 0.44 ppm and a quenching constant (KSV) of 2.74 × 104 M−1. Alternatively, the NaxLiyPr(WO4)2:Tb3+@Arg showed remarkable photocatalytic activity for PA degradation. The UV-Vis spectroscopy findings specify that NaxLiyPr(WO4)2:Tb3+@Arg (Eg = 2.95 eV) might operate as a superior photocatalyst compared to NaxLiyPr(MoO4)2:Tb3+@Arg (Eg = 3.38 eV) nanoparticles. The degradation efficacy of NaxLiyPr(WO4)2:Tb3+@Arg towards PA is around 96.7% within 60 minutes of UV irradiation and the photocatalyst's reusability was monitored to ensure good stability. This remarkable photocatalytic activity of NaxLiyPr(WO4)2:Tb3+@Arg was ascribed to increased migration efficiency of photo-generated electrons and holes. [ABSTRACT FROM AUTHOR]

The existence of industrial pollutants, especially metal ions and organic dyes, in water bodies has put at risk human health and the global environment, which makes it necessary to design dual-functional nanoparticles that not only have excellent luminescence sensing ability but also possess simultaneous photodegradation activity against harmful pollutants. Herein, we have synthesized NaTb(MoO4)2:Dy3+@Phen and NaTb(WO4)2:Dy3+@Phen (Phen = 1,10-phenanthroline) nanoparticles using a hydrothermal synthetic method and evaluated their functional activity for the photoluminescent sensing of Fe2+ ions and photocatalytic degradation of rhodamine B (RhB) in an aqueous medium. The physicochemical characterization of the synthesized nanoparticles was undertaken using various techniques. A photoluminescent study of NaTb(MoO4)2:Dy3+@Phen showed that it is extremely sensitive and displays selective chemical sensing towards Fe2+ ions in an aqueous medium. The PL emission band at 545 nm displayed notable quenching on adding different concentrations of Fe2+ ions to a colloidal solution of the prepared nanoparticles. Moreover, NaTb(MoO4)2:Dy3+@Phen possessed a limit of detection (LOD) of 0.56 ppm and a Stern–Volmer (KSV) constant of 6.35 × 103 M−1 for Fe2+ ions, which establish the high selectivity and sensitivity of the synthesized nanoparticles for Fe2+ ions. Additionally, the NaTb(WO4)2:Dy3+@Phen nanoparticles showed noteworthy photocatalytic activity toward the degradation of RhB in an aqueous medium. The results obtained from UV-Vis spectroscopy clearly indicate that NaTb(WO4)2:Dy3+@Phen (Eg = 3.10 eV) nanoparticles could act as a better photocatalyst than NaTb(MoO4)2:Dy3+@Phen (Eg = 3.72 eV) nanoparticles. The degradation efficiency of NaTb(WO4)2:Dy3+@Phen toward RhB is observed to be about 97.2% within 50 min under UV light and it also shows excellent stability even after four repeated catalytic runs. In general, this work provides a practicable approach for the instantaneous detection of Fe2+ ions and the photocatalytic degradation of RhB in an aqueous medium using NaTb(MoO4)2:Dy3+@Phen and NaTb(WO4)2:Dy3+@Phen as potential dual-functional nanomaterials. [ABSTRACT FROM AUTHOR]

Optically-active luminescent materials based on lanthanoid ions attract significant attention due to their unique spectroscopic properties and the possibility of application as chemical sensors. Five isostructural lanthanoid metal organic frameworks, namely {[Pr(3,4-PDA)(Glu)0.5(H2O)2]CH3CN}(1) and [Ln(3,4-PDA)(Glu)0.5(H2O)2]: Ln = Nd (2), Sm (3), Eu (4), and Tb (5) (where 3,4-PDA = pyridine-3,4-dicarboxylic acid, Glu = glutaric acid), synthesized via the solvothermal method are reported. These lanthanoid metal–organic frameworks were characterized by FTIR, single-crystal X-ray diffraction, powder X-ray diffraction, BET, Hirshfeld surface analysis, DFT calculations, electronic spectroscopy, and photoluminescence techniques. MOFs 1–5 show porous two-dimensional (2D) structures. The luminescence properties of MOFs 4 and 5 demonstrated the range of sensing capabilities for some toxic heavy metals. However, MOFs 4 and 5 are highly sensitive for the detection of Pb2+, exhibiting the most effective luminescence quenching with the lowest detectable change in the signal occurring at ∼0.014 and ∼0.013 ppm of Pb2+ with MOFs 4 and 5, respectively, at room temperature in minutes. The MOF-based luminescence sensors designed in this paper demonstrate a successful and feasible strategy to use pyridine-3,4-dicarboxylic acid-based ligand as an antenna, which can efficiently sensitize Eu3+ and Tb3+ emission. MOFs 4 and 5 show great potential in the application of environmental detection of Pb2+ in water. [ABSTRACT FROM AUTHOR]

The widespread use of antibiotic medication (nitrofurantoin; NFT) in pharmaceuticals poses serious risks to both human and animal health. In addition, NFT residues can be found in or released into nearby groundwater, rivers, lakes and other surfaces, posing grave threats to the health of living beings. Consequently, the synthesis of high-performance sensors and catalyst materials for the specific and ultrasensitive detection and removal of NFT from water and food samples is of significant importance for community health and environmental quality. In this study, we designed NaGd(MoO4)2:Dy3+/Eu3+ and NaGd(WO4)2:Dy3+/Eu3+ nanorods through a simple hydrothermal technique and assessed their functional activity for photoluminescence sensing and photocatalytic degradation of NFT. The physicochemical characterization of the prepared nanorods was explored by different analytical and spectroscopic techniques. The photoluminescent properties of NaGd(MoO4)2:Dy3+/Eu3+ showed that it is highly sensitive and exhibits selective sensing against NFT in aqueous solutions. In particular, the emission band at 558 nm showed a noteworthy quenching effect after adding NFT solution to a colloidal solution of the synthesized nanorod. Significantly, NaGd(MoO4)2:Dy3+/Eu3+ exhibited the limit of detection of 0.12 ppm and a quenching constant of 7.35 - 106 M-1 for NFT, which indicates the high selectivity and sensitivity of the prepared nanorod toward NFT. On the other hand, the NaGd(WO4)2:Dy3+/Eu3+ nanorods possessed exceptional photocatalytic activity against the photodegradation of NFT. The obtained UV-Vis spectroscopy results clearly envisage that NaGd(WO4)2:Dy3+/Eu3+ (Eg = 3.42 eV) nanorods could act as a superior photocatalyst than that of NaGd(MoO4)2:Dy3+/Eu3+ (Eg = 4.02 eV) nanorods. The degradation efficiency of NaGd(WO4)2:Dy3+/Eu3+ toward NFT was observed to be B96% within 45 min under UV irradiation, and it displayed good stability by monitoring the reusability of the photocatalyst. The improved photocatalytic activity was credited to the increased migration efficiency of the photo-generated electrons and holes. [ABSTRACT FROM AUTHOR]

In this work we report hydrothermal synthesis of citric acid-assisted [Ce2(MoO4)3]:Tb3+ nanophosphors. The phase, morphology and optical properties were systematically characterized by X-ray powder diffraction, energy dispersive spectroscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, thermo-gravimetric analysis and photoluminescence spectra. The citric acid-assisted [Ce2(MoO4)3]:Tb3+ nanophosphor was used for detection of heavy metal ions (viz., Pb2+, Zn2+, Fe3+, Cr3+, Mn2+ and Fe2+). It exhibits sharp emission peaks at 490, 545, 585 and 621 nm. Significantly, the peak at 545 nm shows enhancing effect upon addition of heavy metal ions. The luminescence intensity of fabricated nanophosphors was efficiently enhanced upon addition of Pb2+ ions and the degree of enhancement linearly increases with the increasing of Pb2+ ion concentration. The calculated limit of detection (LOD) of Pb2+ is found to be 0.44 ppm and Stern–Volmer enhancement constant (KSV) is 9.1 × 105 M− 1. The lower LOD and higher KSV for Pb2+ ion over the other heavy metal ions suggest the high sensitivity and selectivity of synthesized nanoparticles toward Pb2+ ions. [ABSTRACT FROM AUTHOR]

Pure NaGdF4, NaGdF4:Dy3+, and Dy3+/Tb3+ co-doped NaGdF4 nanoparticles with different concentrations of Tb3+ (ranging from 3 to 20 mol%) were prepared via a hydrothermal method. The influence of the Tb3+ ion content on the phase, crystallite size, morphology, and spectroscopic properties of the NaGdF4:Dy3+/Tb3+ nanophosphors was explored with the help of PXRD, FE-SEM, TEM, HR-TEM, EDS, and photoluminescence studies. Moreover, the synthesized NaGdF4:Dy3+/Tb3+ (3% Tb3+) nanophosphor was functionalized with the asparagine amino acid to render water dispersibility and to sense the heavy metal ions such as Cu2+, Mn2+, Co2+, Zn2+, Ni2+, and Hg2+. Asparagine on the surface of nanomaterial not only prevents aggregation but also increases the stability and solubility of the nanophosphor in aqueous media. The asparagine-functionalized NaGdF4:Dy3+/Tb3+ nanophosphor (Asp-NP) shows sharp emission peaks at 493, 548, 588, and 625 nm. The presence of –NH2 and –COO− groups on the surface of the nanophosphor material helps to detect heavy metal ions via electrostatic interactions. Significantly, the peak at 548 nm displayed a notable quenching effect upon the addition of metal ion solutions to an aqueous solution of the prepared Asp-NP. Particularly, Cu2+ ion showed the lowest limit of detection (1.362 ppm) and highest quenching constant (2.578 × 105 M−1) compared to the other hazardous metal ions, which suggests the high sensitivity and selectivity of the synthesized nanophosphor toward Cu2+ ion. [ABSTRACT FROM AUTHOR]

In this study we demonstrate a Ser-CS (serine-functionalized NaYF4:Ce3+/Gd3+/Eu3+@NaGdF4:Tb3+ core shell) nanophosphor for the effective detection of nitroaromatic derivatives. The Ser-CS nanophosphors have a remarkable sensitivity towards electron deficient nitroaromatics. viz., ortho-nitrophenol (2-NP), para-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), picric acid (PA), 1,3-dinitrobenzene (1,3-DNB) and para-nitrotoulene (4-NT). The presence of serine amino acid residues on the core–shell surface inhibits aggregation and increases the stability and solubility of the probe in aqueous medium. The Ser-CS exhibits strong and sharp emission peaks around 493, 548, 594, 610 and 700 nm. Importantly, the peak centred at 610 nm exhibits a noticeable quenching effect on addition of nitro-compounds to the aqueous solution of the nanophosphor. The high quenching constant (KSV) (4.364 × 104 M−1) and low detection limit (1.67 ppm) for PA imply the high selectivity and sensitivity towards PA relative to other explosive nitroaromatics compounds. [ABSTRACT FROM AUTHOR]

This work reports an eco-friendly hydrothermal approach for the synthesis of hexagonal NaCeF 4 :Tb 3+ /Eu 3+ nanophosphors. The phase, morphology and optical properties were characterized by Powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and photoluminescence (PL) spectroscopy respectively. Herein, the as-synthesized nanophosphor was functionalized with amine rich polyethylenimine (PEI) resulting in development of a luminescent nanoprobe bearing dual sensing functions for hazardous nitroaromatics and heavy metal ions. The strong photoluminescence emission of Eu 3+ ions was selectively quenched upon addition of toxic analytes at concentrations from 10 to 100 ppm due to complex formation between the analytes and PEI functionalized nanostructure. The synthesized nanomaterial shows sharp emission peaks at 493, 594, 624, 657 and 700 nm. Significantly, the peak at 594 nm shows a noticeable quenching effect on addition of toxic analytes to the aqueous solution of the nanocrystals. The nanophosphors are sensitive and efficient for the PA and Fe 3+ ion detection with an LOD of 1.32 ppm and 1.39 ppm. The Stern-Volmer (SV) quenching constant ( K SV ) is found to be 2.25 × 10 5 M -1 for PA and 3.8 × 10 4 M -1 for Fe 3+ ions. The high K SV value and low LOD suggest high selectivity and sensitivity of the nanosensor towards PA and Fe 3+ ions over other analytes. Additionally, a reduced graphene oxide and nanophosphor based nanocomposite was also synthesized to investigate the role of energy transfer involving delocalized energy levels of reduced graphene oxide in regulating the luminescence properties of the nanophosphor. It was observed that PEI plays central role in inhibiting the quenching effect of reduced graphene oxide on the nanophosphor., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)