Visible Absorption Spectra Research Articles

Rational design of an AIEgen for imaging lipid droplets polarity change during ferroptosis

Ferroptosis can regulate cell death by accumulating lipid peroxides, affecting the structure and polarity of lipid droplets (LDs), but clear evidence is still lacking. Fluorescence imaging is the most powerful technique for studying LDs’ function. However, developing AIE fluorescent probes with high selectivity and sensitivity for targeting LDs remains challenging. In this study, we rationally designed an AIEgen, as a novel fluorescent probe TPE-BD, by constructing a push-pull electron structure. The probe has benzo[b]thiophene-3(2H)-one 1,1-dioxide as the electron acceptor, tetraphenylethylene (AIE skeleton) as the electron donor, and thiophene as the bridging group. The optical performance of probe TPE-BD indicated that the UV–visible absorption spectrum of the probe was minimally affected by solvent polarity (except for glycerol and PBS solvents), but the fluorescence of probe is very sensitive to changes in polarity, achieving the goal of polarity detection in LDs. CCK-8 assay and cell imaging experiments demonstrated that probe TPE-BD exhibited good cell compatibility and effectively targeted LDs, enabling the monitoring of LDs’ polarity and quantity during ferroptosis.

A novel algorithm to extrapolate ultraviolet absorption of chromophoric dissolved organic matter from remote sensing ocean color

Accurate estimation of the absorption of chromophoric dissolved organic matter (CDOM) in ultraviolet (UV) wavelength range is crucial for understanding photochemical and biochemical processes in the global ocean. Here, we propose a novel UV absorption extrapolation (UVAE) algorithm. It extrapolates the absorption coefficients (ag(λ) where λ is the wavelength in nm) of CDOM in the UV wavelength range from ocean color data in the visible wavelength range observed by satellite remote sensing. The extrapolation is based on the assumption that three characteristic Gaussian bands describe the CDOM UV–visible absorption spectra (275–443 nm). The UVAE algorithm retrieves the ag(275), ag(295), ag(330), and ag(380) using the characteristics of the spectral slope (S) of the absorbance spectra of CDOM at specific wavelength intervals, namely 275–295, 295–330, 330–380, and 380–443 nm. With the UVAE algorithm, the spatial variability of CDOM spectral features can be captured on a global scale using data from the Moderate-resolution Imaging Spectroradiometer (MODIS) Aqua mission. The retrieved ag(275), ag(295), ag(330), and ag(380) values match well with in-situ observed values, with mean absolute percent differences (MAPDs) of 19.2 %, 26.1 %, 36.9 %, and 46.6 %, respectively. The performance of the UVAE algorithm demonstrates a significant improvement compared to that of existing algorithms, especially for ag(λ) at lower wavelengths.

Synthesis of hollow urchin-like TiO2/N-GQDs composites and efficient photocatalytic degradation research on waste organic dyes

In order to enhance the visible light catalytic activity of TiO2 by broadening its photoresponse range, the TiO2/N-GQDs (TGs) composite catalysts with a three-dimensional hollow urchin-like structure were prepared by one-step hydrothermal method. The microstructure and photoelectric properties of the synthesized TGs composites were analyzed through a series of characterizations, and the performance in degrading organic dyes under visible light was investigated. The results demonstrated that the prepared composites effectively enhanced the visible light absorption spectrum of TiO2 by forming heterojunction. The degradation efficiency of organic dyes could reach 95.71% under visible light irradiation for 1 h, which further increased to 99.39% after 2 h. Additionally, the photocatalytic degradation process could be effectively accelerated under acid conditions. After 5 cycles of testing, the degradation efficiency of TGs composites on organic dyes was hardly reduced, indicating that they had great visible light catalytic activity and significant reusability.

Structural and functional impacts of neonicotinoids analogues on Apis mellifera's chemosensory protein: Insights from spectroscopic and molecular modeling investigations

In the intricate web of ecological relationships, pollinators such as the Italian honeybee (Apis mellifera) play a crucial role in maintaining biodiversity and agricultural productivity. This study focuses on the interactions between three neonicotinoid compounds and the honeybee's chemosensory protein 3 (CSP3), a key player in their olfactory system. Employing advanced spectroscopic techniques and molecular modeling, we explore the binding dynamics and conformational changes in CSP3 upon exposure to these pesticides. The research reveals that all three neonicotinoids considerably quench CSP3's fluorescence through a dynamic and static mixing mechanism, indicating a strong binding affinity, predominantly driven by hydrophobic interactions. UV–visible absorption, synchronous fluorescence, and 3D fluorescence spectra support slight changes in the microenvironment around the aromatic amino acids of CSP3. Circular dichroism spectra indicate a reduction in CSP3's α-helix content, suggesting structural alterations. Molecular docking and dynamics simulations further elucidate the binding modes and stability of these interactions, highlighting the role of specific amino acids in CSP3's binding cavity. Findings provide critical insights into molecular mechanisms by which neonicotinoids may impair honeybee chemosensory function, offering implications for designing safer pesticides and understanding the broader ecological impact of these chemicals on pollinator health.

Enhanced triboelectricity through visible-light-induced surface charges in BTO-polymer hybrid for coexistence solar-mechanical energy harvesting

The exploration of hybrid composites holds great promise in the pursuit of synergistic energy-harvesting solutions, providing an efficient approach to tap into multiple energy sources. One striking example is the BTO (BaTiO3)-polymer hybrid where its high dielectric constant and the piezo-/ferroelectricity are leveraged to improve the triboelectricity of the polymer-based triboelectric nanogenerator (TENG). Beyond this, the BTO also exhibits a photoactive nature, which, until now, has not been exploited to enhance triboelectricity. In this study, a facile method to exploit BTO’s photoresponses in a BTO-polymer hybrid is reported, where surface states present in BTO nanoparticles enable visible spectrum absorption, and the interfaces are designed to facilitate charge spatial separation. Upon visible light illumination, surface charges are generated on the BTO-polymer hybrid, significantly enhancing the photo-induced charge electrification, which in turn boosts the TENG output. These findings demonstrate the possibility of simultaneously harvesting solar and mechanical energies in TENGs using ceramic-polymer hybrids. Additionally, the study employs multiple advanced Scanning Probe Microscopy (SPM) techniques to elucidate the roles of each component and interface in energy harvesting, shedding light on the functional material design. This work not only broadens the variety of energy sources for TENGs but also addresses the growing demand for sustainable and adaptable methods of power generation.

Comparative study of eriochrome black T (EBT) dye adsorption utilizing direct growth of cost-effective efficient materials: S-doped ZnO nanoparticles, ultrathin nanoflakes, and nanowalls

In the present studies, zinc oxide (ZnO) nanoparticles were synthesized by the non-aqueous sol-gel route and incorporated with diverse amounts of the nonmetal element like sulfur with different concentration (1, 2, 4, and 6 wt%). Furthermore, the physicochemical properties of all synthesized nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), N2 adsorption/desorption isotherms, and ultra violate visible (UV-Vis) absorption spectra. Powder XRD analysis shows the formation of hexagonal wurtzite phase of ZnO and the incorporation of S atom in ZnO lattice was confirmed by the XPS analysis. FESEM results reveal that the synthesised S-doped (2, 6 wt%) ZnO samples possess the growth of 1D ultra-thin nanoflakes with sharp edge and vertically aligned 1D thin nanowalls morphology. Moreover, UV-Visible transmission spectral studies showed that the optical energy band gap of ZnO NPs were reduced by S doping. After that, pure ZnO, 1, 4, and 6 wt% S-containing ZnO samples were examined as for adsorption study of eriochrome black T (EBT) dye. Among the S-containing samples, 50 mg of the adsorbent, doped with 4 wt% S (4 wt% S-ZnO) could adsorb up to 95.13 % of EBT dye (15 ppm) in 90 min. Therefore, such a sulfure doped ZnO samples in the form of nanoparticles (NPs), nanoflakes (nanosheets) as well as nanowalls could be used as a promising material for the application in industrial wastewater treatment processes.

Enhancing color brilliance and fastness of polyester dyeing with antipyrine-derived disperse dyes

Disperse azo dyes are important colorants for dyeing polyester fabrics, but developing optimized disperse azo dyes remains a challenge. This work details the synthesis of seven new disperse azo dyes 3a-g derived from the coupling reaction of 4-aminoantipyrine diazonium salt with various phenolic precursors including phenol (3a), salicylic acid (3b), salicylaldehyde (3c), cresols (3d-f), and resorcinol (3g). The dyes were characterized by spectroscopic techniques. Their UV–visible absorption spectra were studied, revealing bathochromic shifts for 3d-g containing electron-donating methyl and hydroxyl substituents compared to parent dye 3a while dyes 3b-c showed hypsochromic shifts. The impact of acid and base on the absorption spectra indicates azo-hydrazone tautomerism for 3f-g but predominant azo form for 3a-e. The dyes showed excellent dyeing on polyester fabrics with up to 97.86 % dye exhaustion. High wash, light and perspiration fastness was exhibited while fastness to respiration varied. The strongest color yield on polyester was achieved with 3g derived from resorcinol coupler. Density functional theory calculations were performed to elucidate relationships between substituent effects and spectral attributes. Lower energy gaps were computed for 3f-g, consistent with enhanced reactivity. This work expands disperse azo dye precursors while offering fundamental structure-performance insight to guide future design. The potent polyester coloration and good fastness properties warrant ongoing investigation of these dyes.

Fabrication of Bi0.90Sm0.1Fe0.97Cr0.03O3@PANI core-shell and improvement of its photocatalyst properties

Bi0.90Sm0.1Fe0.97Cr0.03O3@PANI core-shell structures were made by a two-step method, first, bismuth ferrite nanoparticles by hydrothermal method and then, aniline core-shell by co-precipitation method. The bismuth ferrite (BFO) XRD pattern showed no impurities of Sm, Cr, or their compounds in the samples, indicating that Sm+3 and Cr+3 had been replaced in the BFO structure. The XRD pattern of the Bi0.90Sm0.1Fe0.97Cr0.03O3@PANI core-shell shows all peaks of Bi0.90Sm0.1Fe0.97Cr0.03O3 composition with lower intensity, as a result, the Bi0.90Sm0.1Fe0.97Cr0.03O3 composition is phase single. This lower intensity is attributed to the presence of amorphous polyaniline in the core-shell structure. Since there is in the FT-IR spectrum of the Bi0.90Sm0.1Fe0.97Cr0.03O3@PANI core-shell, characteristic peaks of both polyaniline and bismuth ferrite simultaneously so, the FT-IR spectrum of the Bi0.90Sm0.1Fe0.97Cr0.03O3@PANI core-shell is a perovskite structure. The synthesized samples exhibit weak magnetic properties and behave as a paramagnetic material. The absorption capability of core-shell compared to core nanoparticles has increased in the visible region, and this enhancement is attributed to the influence of the presence of polyaniline. All the peaks in the UV–visible absorption spectrum characterize the nano-sized bismuth ferrite and polyaniline in the UV–visible spectrum of the core-shell. The intensity of the photoluminescence spectrum in the doped sample is significantly higher compared to the core-shell sample. This indicates a much faster recombination rate in the doped nanoparticles compared to the core-shell nanocomposite. The doping of the core with Cr and Sm elements, as well as the coating of the core with a polymeric shell, has led to an increase in the degradation rate of the red dye. We also found that shell thickness plays a vital role in dye degradation efficiency and photocatalytic performance. The Bi0.90Sm0.1Fe0.97Cr0.03O3@PANI core-shell exhibits significant photocatalytic activity under visible light. The photocatalytic studies show that the best sample is Bi0.9Sm0.1Fe0.97Cr0.03O3@PANI core-shell with aniline concentration of 0.2 mL and a pH = 2 which was able to destroy 100 % of Congo red dye molecules.

Biogenic synthesis of copper oxide nanoparticles using Clausena anisata leaf and Euphorbia abyssinica bark extracts and its comparative study of antibacterial activities

Green synthesis of metallic oxide nanoparticles has been used and preferred over physical and chemical methods of synthesis since it is a simple, inexpensive, and environmentally friendly method. This study aims to synthesize copper oxide nanoparticles that were successfully synthesized using Clausena anisata leaf and Euphorbia abyssinica bark by using copper sulphate pentahydrate (CuSO4·5H2O) as a precursor. The copper oxide nanoparticles were synthesized by using 2.5 mL of Clausena anisata leaf and the same amount of Euphorbia abyssinica bark extracts in 10 mL of a 15 mM CuSO4·5H2O solution using the green method. The synthesized copper oxide nanoparticles have been characterized by ultraviolet–visible (UV–Vis) absorption spectra, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The formation of copper oxide nanoparticles was confirmed by the UV–visible absorption spectrum in an intense surface plasmon resonance between 330 and 370 nm, which revealed the formation of copper oxide nanoparticles (CuO NPs). X-ray diffraction (XRD) spectra indicated the crystalline nature of CuO NPs. The average crystalline size of CuO NPs synthesized from Clausena anisata and Euphorbia abyssinica is 47.15 and 19.34 nm, respectively. The FT-IR results showed the existence of bioactive functional groups required for the reduction of copper ions, whereas the results of SEM confirm the green synthesized CuO NPs are spherical in shape. For antibacterial activity studies, the agar disk diffusion method was used. Anti-bacterial activities were studied against three different bacteria: Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli and Enterobacter cloacae) using CuO NPs (100–12.5 mg/mL). Ciprofloxacin and dimethyl sulphoxide, were used as positive and negative controls, respectively. Ciprofloxacin (60 µg/mL) inhibited Escherichia coli, Staphylococcus aureus, and Enterobacter cloacae with inhibition zones of 18, 20, and 25 mm, respectively. The CuO NPs synthesized from Euphorbia abyssinica bark showed higher anti-bacterial activity. Euphorbia abyssinica bark-mediated CuO NPs exhibited inhibition zones of 7, 11, and 13 mm against Escherichia coli, Enterobacter cloacae, and Staphylococcus aureus, respectively. Conversely, Clausena anisata leaf-mediated CuO NPs demonstrated inhibition zones of 8, 14, and 15 mm against the same microorganisms.

Determination of N-centered stereochemistry in N22-methylated chlorophyll-a derivatives and their epimer-dependent optical spectra.

An N-centered epimeric mixture of chlorophyll-a derivatives methylated at the inner nitrogen atom was separated by reverse-phase high-performance liquid chromatography. Circular dichroism (CD) spectroscopic analyses of the epimerically pure N22-methyl-chlorins revealed that the minor first-eluted and major second-eluted stereoisomers were (22S)- and (22R)-configurations, respectively. Their visible absorption and CD spectra in solution were dependent on the N22-stereochemistry. The epimer-dependent spectral changes were independent of the substituents at the peripheral 3-position of the core chlorin chromophore.

The investigation of the interaction determination between carbendazim and elastase, using both in vitro and in silico methods

Pesticides, including fungicides, are one of the important groups of environmental toxins that affect human and animal health. Studies have shown that these compounds are considered chemical pollutants. Carbendazim is a systemic fungicide. Unfortunately, excessive use of carbendazim has caused environmental pollution all over the world. In this study, the effect of carbendazim on the enzyme elastase (secreted from the endocrine gland of the pancreas) has been investigated. In a study, the performance and reaction of carbendazim with elastase were investigated using spectroscopic techniques. The stability and structure of elastase enzymes were studied under the influence of carbendazim. The results of fluorescence emission and UV–visible absorption spectrum showed that in the presence of carbendazim, there is an increase in UV–Vis absorption and a decrease in the intensity of the intrinsic fluorescence emission in the protein spectrum. Additionally, a decrease in the thermal stability of elastase was observed in the presence of carbendazim. The stability and structure of elastase enzyme were investigated in the presence of carbendazim. The results revealed that the UV–Vis absorption increased due to the presence of carbendazim, as indicated by the hyperchromic spectrum at 220 and 280 nm peaks. Additionally, the intrinsic fluorescence emission in the protein spectrum decreased with increasing carbendazim concentration at three different temperatures (298, 303, and 313 K). Moreover, the study demonstrated that the TM decreased from 2.59 to 4.58 with the increase of carbendazim, suggesting a decrease in the stability of the elastase structure in response to the elevated carbendazim concentration. According to the results of the research, the interaction between elastase and carbendazim has occurred, and changes have been made in the enzyme under the influence of carbendazim. The formation of the complex between elastase and carbendazim was consistent with the results obtained from molecular simulation and confirmed the thermodynamic data.

Identification of novel flower anthocyanins of Delphinium grandiflorum cultivars

Flower color is one of the most important properties of ornamental flowers. Information on the kinds of pigments that flowers can biosynthesize is useful for breeding cultivars focused on flower colors. The flower colors of regular ornamental delphinium cultivars are blue, violet, purple, pink, and white. The pigments of these flowers are delphinidin-based anthocyanins. It has been reported that the typical modification in delphinium anthocyanins involves the transfer of glucose and p-hydroxybenzoic acid molecules to the 7-position of delphinidin one by one, and it was predicted that other unidentified anthocyanins are present in addition to the already reported ones. Recently, light pink flowers that accumulate pelargonidin-based anthocyanins were reported from cultivars derived from Delphinium grandiflorum. Converting delphinidin-based anthocyanins to pelargonidin-based ones is considered key to producing red flowers in delphinium. Hence, we investigated anthocyanins of blue, mauve, light pink, and white flowers of D. grandiflorum cultivars. We isolated anthocyanins and analyzed them using HPLC, TLC, UV–vis spectra, FABMS, and NMR. Using these methods, we identified two novel delphinidin-based anthocyanins and three novel pelargonidin-based anthocyanins: delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[6-O-(p-hydroxybenzoyl)-β-glucopyranoside] (2), pelargonidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (5, rubrodelphin), pelargonidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[3-O-(β-glucopyranosyl)-6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (6), delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[3-O-(3-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (7), and pelargonidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[3-O-(3-O-(6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranosyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (9, rosedelphin), along with four known anthocyanins. The flowers of five blue cultivars accumulated cyanodelphin (8) as the dominant pigment. The shapes of visible absorption spectra of these five blue flowers were similar, indicating that the color and the absorption spectra were the typical ones for delphinium blue color produced by 8. The mauve flower color was due to a mixture of delphinidin-based anthocyanins in various polyacylated levels at the 7-position. The light pink flowers accumulated pelargonidin-based anthocyanins 5, 6, and 9. These pigment structures showed that the pelargonidin-based anthocyanins modified in the same way as in the originally biosynthesized delphinidin-based anthocyanins even though aglycone was replaced by pelargonidin in these anthocyanins.

Synthesis of Bio-Base Fluorescence Carbon Dots for Selective Detection of Tartrazine and Sunset Yellow in Food Samples.

A green, economical and simple method for the preparation of water-soluble, high-fluorescent carbon quantum dots (CQDs) has been developed via hydrothermal process using pomelo peels as carbon source. The synthesized CQDs were characterized by transmission electron microscopy (TEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), UV - vis absorption spectra and fluorescence spectrophotometer. The results reveal that the as-prepared C-dots were spherical shape with an average diameter of 2.64nm and emit bright blue photoluminescence (PL) with a quantum yield of approximately 3.63%. The surface of the C-dots was rich in hydroxyl groups and presented various merits including excellent photostability, low toxicity, and satisfactory solubility. Additionally, we found that two widely used synthetic food colorants, tartrazine and sunset yellow, could result in a strong fluorescence quenching of the C-dots, The possible mechanisms are caused by different ratios of inner filter and static quenching effects. According to this property, This study attempts to establish an analytical method for the determination of tartrazine and sunset yellow using carbon quantum dots as fluorescent probe. A linear relationship was found in the range of 0-100 µM tartrazine and sunset yellow with the detection limit(3σ/k) of 0.65 nM and 1.7 nM. The relative standard deviation (RSD) was 3.5% (tartrazine) and 3.0% (sunset yellow).This observation was further successfully applied for the determination of tartrazine and sunset yellow in food samples collected from local markets, and the recovery rates of the two ranges from 79% to 117.8 and 81 -103.5%, respectively. suggesting its great potential toward food routine analysis.

Investigations of structural, photoluminescence, colorimetric, lifetime, and luminous efficiency of Tb3+ and Sm3+ co-doped calcium tungstate for WLEDs

Structure, photoluminescence, colorimetric, and thermoluminescence analysis of Ca1-x-yTb2x/3Sm2y/3WO4; x = 0.01; y = 0.01–0.05 ceramics are reported in this manuscript. The materials are made by the use of the solid-state method. Reitveld refinements of the obtained X-ray diffraction patterns are done by using the Fullprof Suite software. The obtained results denoted that the synthesized materials have a tetragonal structure and I41/a space group. Energy bandgaps are found in the UV–visible absorbance spectra. Photoluminescence investigations of the phosphors are done. The critical quenching concentrations of the phosphor are found to be x = 0.01; and y = 0.04. Moreover, the critical distance of energy shift with the adjacently presented ions is computed. Dexter’s theory is employed to elucidate that the dipole-dipole electronic interactions are the imperative reasons for the transfer of energy in the phosphor. The white color of emission is achieved for x = 0.01, y = 0.04 Tb, and Sm doped CaWO4 material. Moreover, great values in color purity, correlated color temperature, color rendering index as well as luminous efficiency of radiation are obtained from the CIE Chromaticity coordinates. Quantum yield efficiency of x = 0.01, y = 0.04 Tb & Sm codoped CaWO4 is measured. Photoluminescence decay analysis of all the samples is done to study the long-after glow properties and also the average lifetime values are evaluated. This is an indication of the suitable usage of the prepared materials in the white light-emitting diodes. Concentration as well as dose-dependent Thermoluminescence spectroscopy is investigated thoroughly. Kinetic parameters are calculated by deconvoluting the spectra of x = 0.01; y = 0.01 Tb & Sm codoped CaWO4 irradiated with 15 min of UV excitation dose. These results are denoted by high trap depth, second-order kinetics, and low UV dosimetry of the phosphor.

Rapid and complete prediction of alizarin in solution by combining experimental data with computational methods

In the field of cultural heritage, understanding the nature of pigments and dyes is of great importance for conservation issues. Among the many natural dyes used in paintings or textiles, madder was one of the most important sources of red color at the time and was present in a wide variety of objects. However, due to extraction challenges, impurities, and high costs, a lot of information are not easily available. In this publication we designed a computational protocol able to reproduce the spectroscopic properties of two dyes, alizarin and alizarin red S. This framework allows us to compute both Ultraviolet–Visible absorption spectra and Nuclear Magnetic Resonance (NMR) with good accuracy as well as reproduce with precision the CIELAB color. We have also explored different types of interactions that impact these properties, notably the solvation effect. We found that microsolvation is sufficient to reproduce the experimental measurements made in water. The high accuracy of the computation method makes this technique particularly promising for a non-destructive study of dyes on works of art and the preservation of cultural heritage.

Unveiling the enhanced optical limiting of polyaniline – Fullerene composite investigated by z-scan

The reverse saturable absorption (RSA) and optical limiting (OL) mechanisms of polyaniline (PANI) and fullerene doped PANI (PANI-C60) solutions were investigated by open-aperture z-scan studies, using a nanosecond pulsed Nd:YAG laser operating at 532 nm wavelength as the excitation source. The nonlinear absorption coefficient (β), OL threshold, and imaginary part of nonlinear susceptibility (χi(3)) of PANI and PANI-C60 solutions were determined for three different laser input pulse energies and are found to be in the order of 10−9 cm/W, 106 W/cm2, and 10−10 esu respectively. The results showed enhanced OL efficiency for the PANI-C60 solution, making it a promising candidate for applications in optoelectronics and optical limiting. The transmission electron microscope (TEM) images revealed the uniform distribution of C60 of particle size in the range of 5–10 nm in the PANI matrix. The composite formation of PANI-C60 was confirmed by Fourier transform infrared spectroscopy (FTIR). The presence of C60 and its charge transfer complex (CTC) formation with PANI are responsible for the enhanced OL efficiency. The linear refractive index values were measured using UV–Visible absorption spectra and compared with the theoretical values. The investigation of the OL mechanism and the calculation of its associated NLO parameters for PANI and PANI-C60 solutions are reported for the first time.

Gold nanoparticles assisted colorimetric sensing of paroxetine, duloxetine, and olanzapine in aqueous and micellar systems with improved sensitivity

The present study explored a rapid and facile colorimetric identification of two antidepressants (paroxetine and duloxetine) and one antipsychotic drug (olanzapine) in aqueous and micellar systems using citrate-stabilized gold nanoparticles (Cit-AuNPs). The sensing approach involved hydrogen bonding and electrostatic interactions on the surface of Cit-AuNPs. The attributes of Cit-AuNPs and their interactions with the drugs were probed using characterization techniques like UV–Vis spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta potential measurement, and Fourier-transform infrared spectroscopy (FT-IR). Various factors including the volume of Cit-AuNPs, pH, reaction time, surfactant concentration, and the sequence of addition of reagents were optimized to inspect their impacts on sensing results. Under optimized conditions, the probe showed good linearity for the three drugs at the nanomolar (nM) range. Consequently, the color of the Cit-AuNP solution transformed from red to royal purple and blue, which was visible to the naked eye and monitored by visible absorption spectra. This label-free optical detection approach could recognize paroxetine (Prx), duloxetine (Dlx), and olanzapine (Olz) in aqueous system at concentrations ranging from 1 to 17 nM with a limit of detection (LOD) of 0.312, 0.258, and 0.418 nM (S/N = 3), respectively. Meanwhile, the sensitivity was improved in the Triton X-100 (TX-100) micellar system with LOD of 0.029, 0.030, and 0.029 nM for Prx, Dlx, and Olz, respectively accompanied by a shift in the absorption bands. The micellar system contributes stability to the Cit-AuNP-drug complex. The devised colorimetric approach was convenient and did not require any complex equipment. It was efficaciously used to detect three drugs in pharmaceutical products, spiked human urine, and blood serum samples with satisfactory recoveries of 99.83–103.45% and RSD < 3.5%. Notably, the sensing assay demonstrated good selectivity for three drugs in the existence of commonly encountered foreign species and certain common drugs with a relative error below 3%. The results of the present study were statistically compared with reference methodology. The results were validated with no significant difference between the devised and reported approaches considering precision and accuracy, respectively.

Constructing Te doped-CeO2/g-C3N4 heterojunction nanocomposite for visible-light-driven photodegradation of dye pollutant

Industrial wastewater is a particular threat to humans and the surrounding environment, therefore, the design of visible light photocatalysts is urgently required for wastewater treatment. Here, Te-doped CeO2 (CeTeO2) and its heterostructure composite with g-C3N4 (CeTeO2/g-C3N4) catalysts were synthesized via simple sol-gel and ultrasonication techniques. Several characterization tools were used to confirm the composition, morphology, structure, light absorption, and surface features of the CeTeO2 and CeTeO2/g-C3N4 samples. XRD and FTIR confirmed the structural features, BET analysis showed CeTeO2/g-C3N4 gains higher surface area, SEM analysis revealed the morphology, and EDX confirmed the elemental composition. Optical band gaps 2.85 eV and 2.67 eV for CeTeO2 and CeTeO2/g-C3N4 were calculated from UV–vis data. The synthesized catalysts were tested for photocatalytic application, and CeTeO2/g-C3N4 showed excellent results against methylene blue (MB), having 99.9 % degradation efficiency in 60 min. The excellent catalytic results were credited to the S-scheme CeTeO2/g-C3N4 heterojunction, which broadened the absorption in visible spectra and increased redox ability. A model of charge transfer was proposed based on the results that were attained.

Force/Acid-Activated and Radical-Regulated photochromic luminescence in a binuclear Zero-Dimensional complex for multi-level anti-counterfeiting

Traditional static optical anti-counterfeiting technology can only output a single emission signal, which is easy to replicate and difficult to meet the needs in current high-tech fields. Multi-level stimuli-responsive luminescent materials with internal logical relationship can improve the degree of anti-counterfeiting and resist against the flood of counterfeiting. In this work, we propose to use force and acid dual stimuli to restrict the dissipation path of photogenerated free radicals, which further lead to the radical-actuated photochromic luminescence (PCL) performance. Based on this strategy, a zero-dimensional (0D) dinuclear zinc complex Zn2(9-AC)4(IM)2 (1) with blue luminescent properties (450 nm) was designed and synthesized. The interaction between 9-AC and IM (as 9-AC/IM exciplex) can be cut off by force-induced rearrangement of structural units in the spatial dimensions or acid-induced protonation of 9-AC, achieving the luminescent transformation from 9-AC/IM exciplex (447 nm) to 9-AC/9-AC excimer (480 nm) or 9-HAC (485 nm). At the same time, the PCL performance was activated and the emission intensity quenching rate increased from 4.77 % to 93.86 % or 44.93 % under UV light irradiation, respectively. The solid-state ultraviolet–visible absorption spectra, electron paramagnetic resonance spectra and theoretical calculation confirmed that the activation of PCL performance is due to the fact that the 9-AC• radicals are more difficult to dissipate upon force- or acid-induced stimuli. Combining mechanochromic luminescence (MCL) and PCL, a dynamic anti-counterfeiting quick response (QR) code with multi-level and fast-responsive logic sequence have been designed, which are promising for the application in time-resolved information encryption. This work provides an effective strategy to construct multi-level stimuli-responsive luminescence as novel anti-counterfeiting materials by changing the photogenerated free radical dissipation pathway to activate PCL properties.

A high-efficiency clay mineral based organic photocatalyst towards photodegradation of butyl xanthate in mineral processing wastewater

The organic solar cell active layer, well known for excellent visible light response capability, is regarded as a potential candidate for photocatalytic degradation of organic wastewater. However, the poor dispersibility in water due to its hydrophobicity property severely limited the degrading efficiency. In this work, a novel composite photocatalyst PM6:IDT8CN-M/CK2 with a broad visible absorption spectrum and non-toxicity was first synthesized through the intercalation compounding method. A good dispersibility of PM6:IDT8CN-M in wastewater was achieved with the help of rich interlamellar porosity and good hydrophilicity of calcined kaolin. This composite photocatalyst was successfully applied to the SBX photocatalytic degradation in mineral processing wastewater, and the SBX pollutants can be completely degraded within 10 min under the condition of visible light irradiation. Compared with other reported photocatalysts, the photocatalytic degradation efficiency of SBX was dramatically improved by at least seven times. Moreover, PM6:IDT8CN-M/CK2 has remarkable stability, sustaining degradation efficiencies of over 90 % in 60 cycles. Notably, the organic solar cell active layer in PM6:IDT8CN-M/CK2 can achieve carrier rapid separation and transport, enhancing the generation of active oxides (∙O2–, and ∙OH, etc.). At the same time, the large surface area of PM6:IDT8CN-M/CK2 provides a suitable environment for the oxidation reaction of active radicals with SBX to achieve this efficient photocatalytic degradation. Overall, this work not only extends the application scope of organic solar cell active layer, but also develops a high-efficiency SBX removal technique for the treatment of mineral processing wastewater.