Search Results (7)

Thorium is a notable candidate for resolving uranium shortage caused by the global application of nuclear power generation. Uranium extraction from seawater is another attempt to handle its source deficiency, however, vanadium is one of the main competitive elements in that process. Exploration of probes which can discriminatively detect thorium and vanadium from uranium has primary significance for their further separation and for environmental protection. Herein, N′-(2,4-dihydroxybenzylidene)-4-hydroxylphenylhydrazide, AOH, is used as sensor for Th⁴⁺ and vanadyl (VO²⁺) determination. AOH demonstrates a specific “turn-on” fluorescence selectivity towards Th⁴⁺ over f-block and other foreign metal ions, with a detection limit (LOD) of 7.19 nM in acidic solution and a binding constant of 9.97 × 10⁹ M⁻². Meanwhile, it shows a “turn-off” fluorescence response towards VO²⁺ over other metal ions at the coexistence of Th⁴⁺, with a LOD of 0.386 μM in the same media and a binding constant of 4.54 × 10⁴ M⁻¹. The recognition mechanism, based on HRMS, ¹H NMR, and FT-IR results, demonstrates that VO²⁺ causes the fluorescence quenching by replacing Th⁴⁺ to coordinate with AOH. In real water detection tests, Th⁴⁺ and VO²⁺ exhibited satisfying recoveries. These findings expand the application of sensors in nuclide pollution control. Full article

Halogenated metal phthalocyanines are promising materials for the manufacture of active layers of chemiresistive sensors for the detection of various gases. Despite the high interest in such sensors, there are few systematic studies of the position of halogen substituents in phthalocyanine macroring on the chemiresistive response of their films to gases. In this work, we prepared and studied films of novel tetrachlorosubstituted vanadyl phthalocyanine derivatives with Cl substituents in the peripheral (VOPcCl₄-p) and nonperipheral (VOPcCl₄-np) positions of the phthalocyanine ring as active layers of chemiresistive sensors to reveal the effect of the position of substituents on their structure and sensor response to low concentrations of NH₃. It was shown that the films of VOPcCl₄-p exhibited a noticeably higher sensor response to NH₃ than the VOPcCl₄-np ones. The limit of detection of NH₃ was 0.7 ppm. The sensing layers demonstrated a reversible sensor response at room temperature with fairly low response/recovery times. It was also demonstrated that NH₃ can be detected in the presence of various interfering gases (CO₂ and H₂) and some volatile organic vapors, as well as in a mixture of gases with a composition close to exhaled air. Full article

Metalloporphyrin-containing mesoporous materials, named VTPP@SBA, were prepared via a simple anchoring of vanadyl porphyrin (5,10,15,20-Tetraphenyl-21H,23H-porphine vanadium(IV) oxide) through a SBA-15-type mesoporous material. For comparison, vanadyl porphyrin was also impregnated on SiO₂ (VTPP/SiO₂). The characterization results of catalysts by XRD, FTIR, DR-UV-vis, and EPR confirm the incorporation of vanadyl porphyrin within the mesoporous SBA-15. These catalysts have also been studied using electrochemical and photoelectrochemical methods. Impedance measurements confirmed that supporting the porphyrin in silica improved the electrical conductivity of samples. In fact, when using mesoporous silica, current densities associated with oxidation/reduction processes appreciably increased, implying an enhancement in charge transfer processes and, therefore, in electrochemical performance. All samples presented n-type semiconductivity and provided an interesting photoelectrocatalytic response upon illumination, especially silica-supported porphyrins. This is the first time that V-porphyrin-derived materials have been tested for photoelectrochemical applications, showing good potential for this use. Full article

In this work, we presented experimental observation on solution-processed bulk heterojunction organic photodiode using vanadyl 2,11,20,29-tetra tert-butyl 2,3 naphthalocyanine (VTTBNc) as a p-type material. VTTBNc is blended with two different acceptors, which are PC₆₁BM and PC₇₁BM, to offer further understanding in evaluating the performance in organic photodiode (OPD). The blend film of VTTBNc:PC₇₁BM with a volumetric ratio of 1:1 exhibits optimized performance in the VTTBNc blend structure with 2.31 × 10⁹ Jones detectivity and 26.11 mA/W responsivity at a −1 V bias. The response and recovery time of VTTBNc:PC₇₁BM were recorded as 241 ms and 310 ms, respectively. The light absorption measurement demonstrated that VTTBNc could extend the light absorption to the near-infrared (NIR) region. The detail of the enhancement of the performance by adding VTTBNc to the blend was further explained in the discussion section. Full article

Pure and doped vanadia (VO₂, V_0.98Zr_0.02O₂, V_0.98Ce_0.02O₂) samples were prepared by wet chemistry synthesis from vanadyl glycolate intermediate phase and tape casted into films. Combining in-operando grazing incidence synchrotron X-ray diffraction and Raman spectroscopy, we studied the structural evolution of the films under isothermal conditions. The setup allowed assessment of the thermochromic functionality with continuous monitoring of the monoclinic to tetragonal transition in pure and doped vanadia phases, responsible for the transmission and reflection of light in the infrared part of the solar spectrum. The materials characterisation by X-ray diffraction beamline (MCX) goniometer demonstrated ideal performance, combining flexible geometry, high resolution, and the potential to accommodate the multi-channel equipment for in-operando characterisation. This method proved viable for evaluating the relevant structural and physical, and thereof functional properties of these systems. We revealed that dopants reduce the transition temperature by 5 °C on average. The synthetic route of the films was held responsible for the observed phase separation. The more favourable behaviour of cerium-doped sample was attributed to cerium alkoxide behaviour. In addition, structural, microstructural, thermal, and spectroscopic characterisation on powder samples was performed to gain more insight into the development of the phases that are responsible for thermochromic features in a broader range of doping ratios. The influence of the dopants on the extent of the thermochromic transition (transmission to reflection hysteresis) was also evaluated using (micro) structural, thermal and spectroscopic methods of powder samples. Characterisations showed that zirconium doping in 2, 4, and 6 mol% significantly influenced the phase composition and morphology of the precursor. Vanadium oxides other than VO₂ can easily crystallise; however, a thermal treatment regime that allowed crystallisation of VO₂ as a single phase was established. Full article

In this work, thin films of vanadyl phthalocyanines (VOPc and VOPcF₄) are studied as active layers for the detection of gaseous ammonia and hydrogen. The effect of F-substituents on the structural features of vanadyl phthalocyanine films and their sensor response toward ammonia (10–50 ppm) and hydrogen (100–500 ppm) is investigated by X-ray diffraction (XRD) and chemiresistive methods, respectively. It is shown that the sensor response of VOPcF₄ films to ammonia is 2–3 times higher than that of VOPc films. By contrast, the sensor response to hydrogen is higher in the case of VOPc films. Apart from this, the hybrid structures of vanadyl phthalocyanine films with Pd nanoparticles deposited on their surface by a chemical vapor deposition method are also tested to reveal the effect of Pd nanoparticles on the sensitivity of VOPc films to hydrogen. Deposition of Pd nanoparticles on the surface of VOPc films leads to the noticeable increase of their sensitivity to hydrogen. Full article

Jeju ground water, containing vanadium compounds, was shown to increase glutathione (GSH) levels as determined by a colorimetric assay and confocal microscopy. To investigate whether the effects of Jeju ground water on GSH were specifically mediated by vanadium compounds, human Chang liver cells were incubated for 10 passages in media containing deionized distilled water (DDW), Jeju ground water (S1 and S3), and vanadyl sulfate (VOSO₄). Vanadyl sulfate scavenged superoxide anion, hydroxyl radical and intracellular reactive oxygen species. Vanadyl sulfate effectively increased cellular GSH level and up-regulated mRNA and protein expression of a catalytic subunit of glutamate cysteine ligase (GCLC), which is involved in GSH synthesis. The induction of GCLC expression by vanadyl sulfate was found to be mediated by transcription factor erythroid transcription factor NF-E2 (Nrf2), which critically regulates GCLC by binding to the antioxidant response elements (AREs). Vanadyl sulfate treatment increased the nuclear translocation of Nrf2 and the accumulation of phosphorylated Nrf2. Extracellular regulated kinase (ERK) contributed to ARE-driven GCLC expression via Nrf2 activation. Vanadyl sulfate induced the expression of the active phospho form of ERK. Taken together, these results suggest that the increase in GSH level by Jeju ground water is, at least in part, due to the effects of vanadyl sulfate via the Nrf2-mediated induction of GCLC. Full article