Dual-Ligand Strategy Employing Rigid 2,5-Thiophenedicarboxylate and 1,10-Phenanthroline as Coligands for Solvothermal Synthesis of Eight Lanthanide(III) Coordination Polymers: Structural Diversity, DFT Study, and Exploration of the Luminescent Tb(III) Coordination Polymer as an Efficient Chemical Sensor for Nitroaromatic Compounds

Lanthanide coordination polymers (Ln-CPs) are potential chemosensors when fabricated to depict a detectable change in optical properties on interaction with target analytes. This work investigates the interaction of nitroaromatic compounds with Ln-CPs leading to induced changes in fluorescence emission intensity, a crucial strategy to develop a selective and sensitive system for the sensing of nitroaromatics. Approaching toward this objective, solvothermal reactions of 2,5-thiophenedicarboxylic (2,5-TDC) acid, 1,10-phenanthroline (1,10-Phen), and Ln(NO₃)₃·xH₂O are carried out to assemble eight Ln(III) coordination polymers [Ln₂(2,5-TDC)₃(1,10-Phen)₂(H₂O)₂] [Ln = Pr (1), Nd (2)], {[Tb(2,5-TDC)_1.5(1,10-Phen)(H₂O)]·DMF} (3), and [Ln(2,5-TDC)_1.5(1,10-Phen)]·xH₂O (Ln = Tb (4), Dy (5), Ho (6), Er (7), and Yb (8)); x = 0 for CP 4, 5, 6, and 8 and x = 1 for CP 7 with two different space groups and dimensions. The as-synthesized polymers 1-8 are characterized by powder X-ray crystallography, infrared spectroscopy, and thermogravimetric analysis. The structure-corroborated density functional theory (DFT) studies are done on the selected CPs to investigate the interactions between different structural motifs of the assembled CPs. The luminescence properties of CP 4 are explored in detail and are found to be highly sensitive for the detection of p-nitrotoluene as indicated by the most intensive fluorescence quenching with the lowest limit of detection (0.88 ppm) and high quenching constant (4.3 × 10⁴ M^-1). Other nitro compounds (viz., o-nitrobenzaldehyde, m-nitroaniline, picric acid, m-dinitrobenzene, p-nitrophenol, and p-nitroaniline) are also screened for potential sensing by CP 4.

Application of palladium nanoparticles supported organo-kaolinite for 4-chloro-2-nitroaniline catalytic reduction and electrochemical detection

Palladium nanoparticles (PdNPs) supported organo-kaolinite was used as a solid catalyst for the reduction and electrochemical detection of 4-chloro-2-nitroaniline (CNA). During the catalytic reduction in presence of NaBH4, the effects...

PEI functionalized NaCeF4:Tb3+/Eu3+ for photoluminescence sensing of heavy metal ions and explosive aromatic nitro compounds

This work reports an eco-friendly hydrothermal approach for the synthesis of hexagonal NaCeF4:Tb3+/Eu3+ 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 Eu3+ 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 Fe3+ 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 × 105 M-1 for PA and 3.8 × 104 M-1 for Fe3+ ions. The high K SV value and low LOD suggest high selectivity and sensitivity of the nanosensor towards PA and Fe3+ 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.

Synthesis of Cerium Tetrafluoride and Cerium Trifluoride Nanoscale Polycrystals from Ammonium Hydrogen Difluoride

This paper reported a dry synthesis and characterization of cerium tetrafluoride (CeF₄) and cerium trifluoride (CeF₃) nanoscale polycrystals (NPs). The CeF₄ NPs were spherical or flaky and approximately 10 ± 2 nm in diameter. The CeF₃ NPs were rod-shaped nanorods with a length of about 150 ± 5 nm and a diameter of about 20 ± 2 nm. The first step was to synthesize the intermediate product-(NH₄)₄CeF₈ by mixing CeO₂ and NH₄HF₂ at a molar ratio of 1:6 at 390 K. The structural characterization was analyzed by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Then, (NH₄)₄CeF₈ was heated in an argon gas flow to synthesize the CeF₃ and CeF₄ NPs. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The properties of CeF₃ and CeF₄ NPs were further evaluated by transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED), and high-resolution transmission electron microscopy (HRTEM). The findings provided an alternative strategy for the synthesis of nanometer fluorides, which could be a reference for high-performance research on other nanometer fluorides.