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Highly Selective Photocatalytic Reduction of o-Dinitrobenzene to o-Phenylenediamine over Non-Metal-Doped TiO2 under Simulated Solar Light Irradiation
摘要： Photocatalytic reduction and hydrogenation reaction of o-dinitrobenzene in the presence of oxalic acid over anatase-brookite biphasic TiO2 and non-metal-doped anatase-brookite biphasic TiO2 photocatalysts under solar simulated light was investigated. Compared with commercial P25 TiO2, the prepared un-doped and doped anatase-brookite biphasic TiO2 exhibited a high selectivity towards the formation of o-nitroaniline (85.5%) and o-phenylenediamine ~97%, respectively. The doped anatase-brookite biphasic TiO2 has promoted photocatalytic reduction of the two-nitro groups of o-dinitrobenzene to the corresponding o-phenylenediamine with very high yield ~97%. Electron paramagnetic resonance analysis, Transient Absorption Spectroscopy (TAS) and Photoluminescence analysis (PL) were performed to determine the distribution of defects and the fluorescence lifetime of the charge carriers for un-doped and doped photocatalysts. The superiority of the doped TiO2 photocatalysts is accredited to the creation of new dopants (C, N, and S) as hole traps, the formation of long-lived Ti3+ defects which leads to an increase in the fluorescence lifetime of the formed charge carriers. The schematic diagram of the photocatalytic reduction of o-dinitrobenzene using the doped TiO2 under solar light was also illustrated in detail.
关键词： selectivity,photocatalysis,non-metal-doped TiO2,nitroaromatic compounds,reduction
更新于2025-09-23 15:22:29
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Synthesis of eight isostructural 2D lanthanide coordination polymers assembled by rigid furan-2,5-dicarboxylic acid and flexible adipic acid as linkers and exploration of luminescent Eu/Tb polymers as efficient and sensitive sensors for nitroaromatic compounds
摘要： Detection of hazardous chemicals is crucial for a healthy and safe environment as well as for the well-being of humans. A confluence of chemistry and engineering continues to improve the sensitivity and selectivity for several classes of harmful chemicals with the promise of cheap and portable sensing. Herein, following the function-oriented research strategy, eight novel lanthanide coordination polymers (Ln-CPs) have been successfully assembled with the framework composition [Ln(2,5-FDC)0.5(Adip)(H2O)2] (Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), 2,5-FDC2? = furan-2,5-dicarboxylate, Adip2? = Adipate) under solvothermal synthesis conditions. The structural analysis indicates that all the eight CPs have the same structural features. All compounds crystallize in the orthorhombic crystal system (space group Pnma) with point symbol {33·44·53} and consist of 2D cem topological type. The linkers 2,5-FDC2? and Adip2? exhibit μ2-κ4,Z1:Z1:Z1:Z1 and μ3-κ5,Z2:Z1:Z1:Z1 coordination modes respectively. The as-synthesized polymers were characterized by powder X-ray crystallography, infrared spectroscopy, thermogravimetric analysis, and photoluminescence studies. CP-3 and CP-5 are promising luminescent lanthanide coordination polymers (Ln-CPs) and function as efficient sensors for the detection of nitroaromatic compounds at the ppm level in mix N,N′-dimethyl formamide-aqueous medium via the luminescence quenching mechanism.
关键词： furan-2,5-dicarboxylic acid,lanthanide coordination polymers,adipic acid,luminescent sensors,nitroaromatic compounds
更新于2025-09-23 15:21:01
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8-Hydroxyquinolinate-Based Metal–Organic Frameworks: Synthesis, Tunable Luminescent Properties, and Highly Sensitive Detection of Small Molecules and Metal Ions
摘要： Five new metal?organic frameworks, [Zn2L2]·2DMF·2MeOH (1), [Zn2L2(py)2] (2), [Cd2L2]·Diox·MeOH·6H2O (3), [Mn2L2]·2DMF·2MeOH (4), and [Co2L2]·2DMF·4H2O (5), were assembled by using a novel 8-hydroxyquinolinate derivative H2L with different metal ions. Complex 1 features a 3D porous network consisting of meso-helical chains (P + M) built from metal?ligand coordination bonds. The adjacent dinuclear ZnII building blocks in 2 are connected together to generate a 2D grid network. In complex 3, each binuclear motif is bound to four ZnII ions to produce a 2D layer structure that stacks into a 3D porous structure. The framework of complex 4 is isostructural to 5, featuring a 21 helical chain built from [M2L2] units (M = Mn or Co). The adjacent meso-helices associated in parallel are interconnected by the phenolate μ2-O atoms of H2L to give rise to a 2D network. Distinct solid-state luminescence properties of 1?3 were observed, arising from their different metal nodes and frameworks. In particular, complex 1 exhibited excellent stability in both common organic solvents and H2O, thus facilitating its utility as a chemical sensor. Remarkably, luminescent 1 showed highly sensitive detection for nitroaromatic molecules in methanol and Fe3+ ion in H2O even in the presence of other interfering metal cations.
关键词： metal-organic frameworks,nitroaromatic compounds,Fe3+ ion,sensing,water stability,luminescence
更新于2025-09-19 17:15:36
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Water-dispersed fluorescent silicon nanodots as probes for fluorometric determination of picric acid via energy transfer
摘要： Water-dispersed fluorescent silicon nanodots (SiNDs) were synthesized by a one-pot hydrothermal method starting from tetraethyl orthosilicate (TEOS) as silicon source and trisodium citrate as reducing reagent. The method is simple and convenient. The SiNDs, with excitation/emission peaks at 347/440 nm and with fluorescence quantum yield of 18% are shown to be viable fluorescent probes for picric acid (PA). The SiNDs strongly bind PA, and their blue fluorescence is quenched. The distance between the donor and acceptor (R0 value) is calculated from fluorescence data to be 2.1 nm. A fluorometric method was worked out that has a linear response in the 8 nM to 50 μM PA concentration range and a 0.92 nM limit of detection. The method has a fast response (2 min) and is well selective over other nitroaromatic compounds and metal ions. The average recoveries from spiked lake water samples ranged between 98.4 and 100.8%.
关键词： Nitroaromatic compounds,Picric acid (PA),Fluorometric determination,Tetraethyl orthosilicate (TEOS),Hydrothermal strategy
更新于2025-09-04 15:30:14