Chalcone-based Turn-Off Chemosensor for Selective and Susceptible Detection of Fe2+ Ions: Spectroscopic and DFT Investigations.

Herein, in this report we are introducing newly synthesized chalcone derivative, "(E)-1-phenyl-3-(4-((5-(((Z)-thiophen-2-ylmethylene)amino)-1,3,4-thiadiazol-2-yl)thio)phenyl)prop-2-en-1-one" (5), as a chemosensor to detect Fe2+ metal ions in HEPES buffer solution of pH 7.5. Spectroscopic techniques were used to confirm the synthesized sensor. To determine the chemical reactivity and molecular stability of the probe, a frontier molecular orbitals investigation was carried out. A molecular electrostatic potential map was investigated to know the binding site of 5 for metal ion coordination. The theoretical absorption and fluorescence emission properties were estimated and correlated with the experimental observations. The sensor showed excellent selectivity for Fe2+ compared to all other studied metal ions. The fluorescence binding studies were carried out by adding different amounts of Fe2+ ions for a fixed concentration of probe 5. The inclusion of Fe2+ ions resulted in a decrease in fluorescence intensity with a bathochromic shift of emission wavelength of 5 due to the 5-Fe2+ complexation. The binding affinity value for the probe was found to be 576.2 M-1 with the help of the Stern-Volmer plot. The Job's plot and mass spectra supported the 2:1 (5: Fe2+) stoichiometry of complex formation. The detection limit and limit of quantification of 5 for Fe2+ were calculated to be 4.79 × 10-5 M and 14.54 × 10-5 M. Further, in addition to this, the photophysical parameters such as fluorescence lifetime of 5 and 5-Fe2+ complex measured to be 0.1439 and 0.1574 ns. The quantum yield of 5 and 5-Fe2+ was found to be 0.0398 and 0.0376. All these experimental findings revealed that probe 5 has excellent selectivity and sensitivity for Fe2+ ions.

Barium Lanthanum Oxide Nanosheets in Photocatalytic and Forensic Applications: One-Pot Synthesis and Characterization.

The present work elucidates the fabrication of Barium Lanthanum Oxide nanosheets (BaLa2O4 NSs) via a simple one-pot precipitation method. The acquired results show an orthorhombic crystal system with an average crystallite size of 27 nm. The morphological studies revealed irregular-shaped sheets stacked together in a layered structure, with the confirmation of the precursor elements. The diffused reflectance studies revealed a strong absorption between 200 nm and 350 nm, from which the band-gap energy was evaluated to be 4.03 eV. Furthermore, the fluorescence spectrum was recorded for the prepared samples; the excitation spectrum shows a strong peak at 397 nm, attributed to the 4F7/2→4G11/2 transition, while the emission shows two prominent peaks at 420 nm (4G7/2→4F7/2) and 440 nm (4G5/2→4F7/2). The acquired emission results were utilized to confirm the color emission using a chromaticity plot, which found the coordinates to be at (0.1529 0.1040), and the calculated temperature was 3171 K. The as-prepared nanosheets were utilized in detecting latent fingerprints (LFPs) on various non-porous surfaces. The powder-dusting method was used to develop latent fingerprints on various non-porous surfaces, which resulted in detecting all the three ridge patterns. Furthermore, the as-synthesized nanosheets were used to degrade methyl red (MR) dye, the results of which show more than 60% degradation at the 70th minute. It was also found that there was no further degradation after 70 min. All the acquired results suggest the clear potential of the prepared BaLa2O4 NSs for use in advanced forensic and photocatalytic applications.

Nano-catalytic behavior of CeO2 nanoparticles in dye adsorption: Synthesis through bio-combustion and assessment of UV-light-driven photo-adsorption of indigo carmine dye.

This study explores the adsorption of indigo carmine dye using bio-combusted cerium oxide nanoparticles (CeO2 NPs). CeO2 NPs were synthesized using a bio-combustion method, and then subjected to structural, morphological, and optical characterization for thorough investigation. Structural investigation was carried out using X-ray diffraction (XRD), which revealed a cubic structure with evaluated average crystallite size of 11.55 nm. Later, the same was verified by employing W-H plot (13.57 nm). UV-Vis spectroscopy revealed an effective band gap of 3 eV suited for photocatalytic applications. The metal-oxygen phonon band at 986.32 cm-1 and 871.96 cm-1 is confirmed using Infrared Spectroscopy (FTIR). The morphological analysis was done using Transmission and Scanning Electron Microscopy (TEM and SEM), which revealed well-dispersed, aggregated structure enclosing spherical nanoparticles with an average size of ∼14 nm. The early precursors were validated using EDAX analysis and SEM. Optical characteristics were investigated using photoluminescence (PL), which revealed a large charge transfer band between 360 nm and 435 nm. The dye removal efficiency of CeO2 NPs was evaluated against Indigo Carmine dye using UV light. The results showed that the significantly adsorption, with more than 70 % removed after 150 min. Kinetic experiments revealed that the depreciation occurred via a pseudo-first-order reaction process. Furthermore, the impacts of certain factors such as dye dosage, pH, reusability, and scavenger on adsorption rate were explored and shown to be effective values for the adsorption process. This study emphasizes the potential of CeO2 NPs as excellent photocatalysts for environmental remediation, especially in dye removal applications.

Investigations of adsorption and photoluminescence properties of encapsulated Al-ZnO nanostructures: Synthesis, morphology and dye degradation studies.

This study focuses on the solution combustion approach to examine the nanostructures of undoped and doped ZnO with different concentrations of Al (0.1 % and 0.2 %). Various physical techniques were utilized to characterize the synthesized nanoparticles. X-ray diffraction (XRD) revealed the crystalline materials, while scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) findings confirmed the products with particle size and the insertion of Al into the ZnO lattice. Fourier-transform infrared spectra (FTIR) confirmed the presence of different functional groups in the obtained material. The results indicate that Al-doped ZnO (Al-ZnO) nanoparticles show promising properties for optoelectronics and photoluminescence. Photoluminescence analysis indicated that an increase in Al3+ (0.2 %) concentration resulted in a decrease in peak intensity and an increase in the full width at half maximum. The band gap was calculated using the Taucs plot. The study also highlights the effectiveness of Zn1-xAlxO nanostructures in degrading organic pollutants, particularly in adsorbing Malachite Green (MG) dye. Among the samples, the 0.2 % Al-doped ZnO exhibited superior dye degradation efficiency due to its enhanced adsorption capacity and smaller particle size, as evidenced by multilayer adsorption capacity and chemisorption during the degradation process. This study provides valuable insights into the potential applications of Al-doped ZnO nanoparticles in various environmental and technological fields, emphasizing their significance in the degradation of organic pollutants.

Pectin/PVA and pectin-MgO/PVA films: Preparation, characterization and biodegradation studies.

There is a great demand to replace non-renewable materials with eco-friendly renewable materials for many applications in recent times. In the present study, such an attempt was made to substitute synthetic polymer-based films used for food packaging applications with films prepared out of renewable materials derived from waste. The pectin/polyvinyl alcohol (PP) and pectin-MgO/polyvinyl alcohol (PMP) films were prepared and characterized to ascertain their suitability for packaging applications. To improve the mechanical strength and thermal stability of films, MgO nanoparticles were incorporated in situ into the polymer matrix. The pectin used in the study was extracted from citrus fruit peel. The prepared nanocomposite films were evaluated for physico-mechanical properties, water contact angle, thermal stability, crystallinity, morphology, compositional purity and biodegradability. The elongation at break for PP film was 42.24% and for PMP film it was 39.18%. Also, the ultimate modulus in terms of MPa for PP film was 6.8 and for PMP it was 7.9. So, it was found that PMP films have better ductility and modulus than PP films due to the presence of MgO nanoparticles. The spectral studies confirmed the compositional purity of the prepared films. The biodegradation studies revealed that both films could be degraded at ambient conditions at appreciable time span, suggesting them to be a better choice as an environmentally friendly food packaging material.