UV Vis Absorption Research Articles

Colorimetric detection of pyrophosphate using gold nanorods and Fe3+ based on anti-etching mechanism

Pyrophosphate (PPi), as a derivative of inorganic phosphate, has important applications in the fields of food and environment, it also plays an important role in biological metabolism and serves as a biomarker for clinical diagnosis of certain diseases. Thus, the development of a simple and convenient method to quantify PPi is of great significance for environmental protection, food safety and disease diagnosis. In this study, visual colorimetric detection of PPi was achieved by inhibiting the morphological change of gold nanorods (Au NRs). In the presence of SCN-, Fe3+ with low concentration can oxidatively etch Au NRs due to the potential difference, leading to significant color change of Au NRs solutions and blue shift in longitudinal local surface plasmon resonance (LSPR) absorption peak of Au NRs solutions. Due to the strong complexation between PPi and Fe3+, the etching of Au NRs by Fe3+ was restrained, while the morphology of Au NRs, the color and UV–vis absorption spectrum of Au NRs solution remained uninfluenced. Under optimal conditions, this colorimetric detection method exhibited exceptional selectivity, anti-interference, and sensitivity towards PPi, with a linear detection range of 0.8–24 μM. Moreover, practical application results suggest that this colorimetric method holds significant potential for swiftly detecting PPi in intricate samples.

Exploring the therapeutic potential of microwave-assisted biosynthesized silver nanoparticles using Erica manipuliflora Salisb.: A comprehensive study on anticancer and antibacterial potentials

Silver nanoparticles (AgNPs) continue to attract interest due to their potential applications in biomedicine, especially in relation to their antibacterial and anticancer properties. In this respect, it is important to develop biosynthesis techniques that are environmentally friendly and include new sources. This is the first report on microwave-assisted green synthesis of silver nanoparticles using Erica manipuliflora Salisb. (E.m AgNPs). In this study, the anti-cancer and antibacterial activity of E.m AgNPs and E. manipuliflora extracts were evaluated. Characterization of E.m AgNPs were performed using UV–Vis spectroscopy FT-IR, XRD, SEM and TEM analyses. The UV–Vis absorption spectrum showed the characteristic peak of E.m AgNPs at λmax = 425 nm. The SEM and TEM results indicated that the nanoparticles were spherical and ranged in size from 2.45 to 9.95 nm. The antibacterial results, it was determined that E.m AgNPs (50 mg mL−1) (8.4–21.1 mm ZOI) caused more effective inhibition on both gram positive (Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis) and gram negative (Escherichia coli) bacteria compared to all plant extracts (50 mg mL−1) (8.13–17.16 mm ZOI). Among the cancer (MCF-7 and HT-29) and healthy (HaCaT and HEK-293) cell lines, E.m AgNPs exhibited the highest cytotoxicity against MCF-7 cells (IC50: 87.22 μg mL−1). The hexane extract was the most effective inhibitory extract on cell proliferation of all cell lines and showed the highest cell inhibition in MCF-7 cells (IC50: 43.06 μg mL−1). The results revealed that both E.m AgNPs and E. manipuliflora extracts showed promising antibacterial activity against pathogenic bacterial strains and had potential anticancer activity.

Novel Eu3+-Doped Glasses in the MoO3-WO3-La2O3-B2O3 System: Preparation, Structure and Photoluminescent Properties.

Novel multicomponent glasses with nominal compositions of (50-x)MoO3:xWO3:25La2O3:25B2O3, x = 0, 10, 20, 30, 40, 50 mol% doped with 3 mol % Eu2O3 were prepared using a conventional melt-quenching method. Their structure, thermal behavior and luminescent properties were investigated by Raman spectroscopy, differential thermal analysis and photoluminescence spectroscopy. The optical properties of the glasses were investigated by UV-vis absorption spectroscopy and a determination of the refractive index. Physical parameters such as density, molar volume, oxygen molar volume and oxygen packing density were determined. The glasses are characterized by a high glass transition temperature. Raman analysis revealed that the glass structure is built up mainly from tetrahedral (MoO4)2- and (WO4)2- units providing Raman bands of around 317 cm-1, 341-352 cm-1, 832-820 cm-1 and 928-935 cm-1. At the same time, with the replacement of MoO3 with WO3 some fraction of WO6 octahedra are produced, the number of which increases with the increasing WO3 content. A strong red emission from the 5D0 level of Eu3+ ions was registered under near-UV (397 nm) excitation using the 7F0 → 5L6 transition of Eu3+. Photoluminescence (PL) emission gradually increases with increasing WO3 content, evidencing that WO3 is a more appropriate component than MoO3. The integrated fluorescence intensity ratio R (5D0 → 7F2/5D0 → 7F1) was calculated to estimate the degree of asymmetry around the active ion, suggesting a location of Eu3+ in non-centrosymmetric sites. All findings suggest that the investigated glasses are potential candidates for red light-emitting phosphors.

Probing the Closed Association of Oligoquinoline Foldamers by Time-Resolved Fluorescence Anisotropy.

The metal-mediated dimerization of oligoquinoline foldamers terminated at one end with an oligo(phenylenevinylene) and at the other with a carboxylic acid (OPV-QnA, where n = 4, 8, 17, and 33), and the complexation of OPV-Q8A and Q16A was promoted in chloroform by the addition of a concentrated 16 M aqueous sodium hydroxide solution. UV-vis absorption and time-resolved fluorescence anisotropy (TRFA) experiments were conducted to determine, respectively, the concentration and the average rotational time ⟨ϕ⟩ of the mixture of unassociated and associated foldamers across a range of foldamer concentrations spanning 5 orders of magnitude. Plots of ⟨ϕ⟩ as a function of acid group concentration revealed that ⟨ϕ⟩ increased with increasing foldamer concentration only when the foldamer solution in chloroform was vigorously mixed with the 16 M sodium hydroxide aqueous solution. Furthermore, all plots showed that ⟨ϕ⟩ reached a plateau at high foldamer concentration. The increase in ⟨ϕ⟩ reflected the association of foldamers into larger objects through metal ion coordination with the carboxylate anions generated by deprotonation of the carboxylic acid of OPV-QnA with NaOH, while the plateau obtained at high foldamer concentration indicated that these interactions led to the dimerization of the foldamers via a closed association mechanism. Analysis of the ⟨ϕ⟩ trends yielded the equilibrium constants (K) describing the foldamer dimerization, whose value equaled 1.0 (±0.2) × 106 M-1 for the three longer OPV-QnA foldamers, but was about 10 times smaller for the shortest one (n = 4). Association of OPV-Q8A and Q16A yielded a complex with a ⟨ϕ⟩ matching that of OPV-Q24A, and K for this complexation was similar to that for dimerization. These experiments illustrate the robust nature of TRFA as an experimental method to probe the size of rigid, self-assembled foldamers in solution.

Effect of ANSA as an additive on electrodeposited Sn-Ag-Cu alloy coatings in deep eutectic solvent

This study investigates the electrodeposition of Sn-Ag-Cu ternary solder coating in a choline chloride-ethylene glycol DES using 1-amino-2-naphthol-4-sulfonic acid (ANSA) as an additive. The mechanism of ANSA was evaluated through UV–visible absorption spectroscopy, infrared spectroscopy, and CV. The results demonstrate that ANSA, as a multifunctional organic compound, influences the electrodeposition process through its sulfonic acid, amino, and naphthyl groups. When the ANSA concentration is below 600 ppm, its primary action is through an interfacial adsorption mechanism, where lone pairs of electrons on nitrogen and oxygen atoms adsorb onto the electrode surface, and the bulky naphthyl ring inhibits the formation of large deposits. As the ANSA concentration exceeds 600 ppm, complexation becomes the dominant mechanism, competing with the complexation of chloride ions (Cl−) in the choline chloride electrolyte. SEM analysis indicates that as the ANSA concentration increases, the deposited coatings become smoother, denser, and exhibit finer grain sizes. The Scharifker-Hills model was employed to analyze the CA curves before and after the addition of ANSA, revealing that the nucleation mechanism of Sn-Ag-Cu alloy deposition gradually transitions from instantaneous nucleation to progressive nucleation with increasing ANSA concentration.

DFT and TD-DFT studies to elucidate the configurational isomers of ferric aerobactin, ferric petrobactin, and their ferric photoproducts.

Iron-chelating siderophores such as aerobactin and petrobactin are produced by marine bacteria to sequester iron under low iron stress. Those that contain a citrate moiety undergo light-catalyzed ligand-to-metal charge transfer, inducing decarboxylation and formation of photoproducts. In this work, we employed density functional theory to obtain the optimized geometries and determine the relative energies and geometric parameters of different configurations of Fe(III)-coordinated aerobactin, petrobactin, and their photoproducts. Time-dependent density functional theory was then used to compute the UV-Vis absorption spectra of these species, and the comparison against experimental spectra further elucidated the structural configurations most likely to be adopted by these compounds. Frequency calculations provided Fe-O force constants on the same order as other siderophores. The relative energies and predicted spectra support the cis-cis C-fac configuration for ferric aerobactin and the cis-trans C-mer configuration for its photoproduct, while only mild support is found for specific configurations of the ferric petrobactin structures (meta-mer and meta-fac for the precursor, cis-cis para-fac for the photoproduct). The predicted ferric petrobactin spectra are found to be fairly insensitive to the configuration of the ferric complex.

DNA and hemoglobin binding activities: Investigation of coumarin-thiosemicarbazone hybrids

Coumarin and coumarin-thiosemicarbazone hybrids were synthesized and characterized by various techniques such as FT-IR, 1H NMR, 13C NMR, MALDI-TOF-MS spectroscopy, and single crystal X-Ray diffractometer (XRD). The photochemical and photophysical properties of the compounds, such as solvatochromism, solubility, and chemical reactivity, were analyzed using UV–vis spectroscopy in different solvents. Due to the potential biological activities of the synthesized compounds, their binding affinity and mechanisms with calf thymus DNA (ct-DNA) and bovine hemoglobin (BHb) were determined using several useful spectrophotometric and theoretical approaches such as UV–vis absorption and fluorescence spectroscopy, molecular docking, and density functional theory (DFT). The experimental results showed that the compounds exhibited strong binding interactions with DNA and BHb. Additionally, the compounds demonstrated predominantly binding modes, such as intercalation and groove binding with DNA and π–π stacking interactions with BHb.To better understand the thermodynamics of these interactions, quenching constants, binding constants, and Gibbs free energy changes (ΔG°) were calculated. Molecular docking and DFT results supported the experimental data regarding the binding affinity and mechanisms of the compounds to DNA and BHb. Overall, this comprehensive study on coumarin and coumarin-thiosemicarbazone hybrids provides valuable insights into their interaction mechanisms with critical biomolecules, highlighting their potential in therapeutic applications as multifunctional agents.

A crude, cold-pressed oil from elderberry (Sambucus nigra L.) seeds: Comprehensive approach to properties and characterization using HPLC, DSC, and multispectroscopic methods

The physicochemical characterization of fresh, undiluted, cold-pressed oil from elderberry seeds (EO) is presented. The results showed EO's uniqueness for the 93 % presence of essential fatty acids, including linoleic n-6 (41 %), α-linolenic n-3 (38 %), and oleic n-9 (13 %) acids with favorable ratios for human nutrition, n-3/n-6 = 0.93. A γ-tocopherol is the dominant tocopherol (96 %), with a concentration of 20.62 mg/100 g, indicating low oil oxidative stability. DSC heating and cooling traces determined the thermal properties. These results also revealed the presence of metastable triacylglycerol (TAG) structures composed of polyunsaturated fatty acids. The presence of characteristic groups for fatty acids and TAGs in EO was confirmed by FTIR-ATR spectra. For the first time, Langmuir monolayer studies on EO revealed its low compressibility, indicating its low emulsifiability, and the presence of minor components of EO, including tocopherols, phenolic acids, polyphenols, flavonoids, and carotenoids, was determined using UV–Vis absorption and fluorescence excitation-emission matrix (EEM) along with the chemometric method.

MoS2-CZTS: a 2D-3D nanocomposite to enhance the photocatalytic performance in degradation of methylene blue dye

Cu2ZnSnS4 nanocrystals (CZTS NCs), MoS2 nanosheet (NS) and MoS2-CZTS nanocomposite (NC) have been synthesized using solvothermal route. Structural characterization of samples have been done by XRD, Raman spectroscopy, HR-TEM. Samples have optically characterized by UV-Vis absorption, photoluminescence (PL) and time co-related single photon counting (TCSPC) study. The XRD, HR-TEM and Raman spectroscopy established tetragonal kesterite phase for both CZTS NCs and MoS2-CZTS NC. Enhancement of efficiency of CZTS NCs to degrade methylene blue (MB) dye, illuminated by visible light, have been observed by loading 1 wt.% MoS2 NS and found to be ~100% in only 15 minutes. This is due to efficent transfer of charge carriers at p-CZTS and n-MoS2 heterojunction interface, confirmed by quenching of PL intensity and decrease in average lifetime of carriers.

Synthesis, comprehensive characterization and investigation of biological properties of newly synthesized Pt(II)-aminothiazole complexes: Combining experimental and computational approach

The synthesis of new platinum(II) complexes with 2-amino-6-methyl-benzothiazole and 2-amino-6-chlorobenzothiazole as ligands were reported and the proposed structure of the complexes were determined using elemental microanalysis, infrared, 1H and 13C NMR spectroscopy. To verify the suggested structures a computational approach utilizing Density Functional Theory was implemented. The results showed a strong correlation with experimental data, confirming the hypothesized structures of investigated compounds.The interactions of novel platinum(II) complexes with human serum albumin and calf thymus DNA were studied by fluorescence spectroscopy and UV-Vis absorption. The predominantly elevated values of the binding constant, Kb, and the Stern-Volmer quenching constant, KSV, stem from the effective attachment of complexes to both HSA and CT-DNA. To establish the mode of interaction, viscosity measurements were conducted. The results showed that complexes are not performing intercalation between the DNA bases, and which probably bind to minor/major grooves.In vitro cytotoxic effect of ligands and platinum(II) complexes was evaluated in the panel of cancer cell lines (mouse mammary carcinoma and colon cancer, and on human mammary carcinoma and colon cancer), and on non-tumor cells, mouse mesenchymal stem cell line using MTT assay. Platinum(II) complex with 2-amino-6-methyl-benzothiazole showed a very good cytotoxic activity mainly by inducing apoptosis.In vitro antimicrobial assay of ligands and complexes was tested against 11 microorganisms using microdilution method and the minimum inhibitory concentration and minimum microbicidal concentration were identified. All tested compounds exhibited moderate antifungal activity and significantly better action on S. aureus ATCC 25923.

Luminescent Mannich bases: Synthesis, crystal structures, and photophysical properties

Three Mannich bases have been obtained starting from 5-bromo-salicylaldehyde: 5-bromo-3-(((2-(dimethylamino)ethyl)(methyl)amino)methyl)-2-hydroxybenzaldehyde (TMEN), 5-bromo-3-((benzyl(methyl)amino)methyl)-2-hydroxybenzal-dehyde (MBA), 5-bromo-3-(ethyl(methyl)amino)methyl)-2-hydroxybenzaldehyde (EMA). The crystal structure of MBA has been solved. The UV-Vis absorption and emission spectra were investigated in different solvents, revealing the presence of several species, the neutral forms, the zwitterionic, the anionic and the cationic (the protonated nitrogen) ones. In order to characterize the last two species, further experiments were performed in the presence of hydrogen extracting and hydrogen donating compounds, sodium fluoride (NaF) and tetra butyl ammonium hydroxide (TBOH) to evidence the anion, and trichloroacetic acid (TCA) for the protonated cation. The experimental results were rationalized by DFT calculations of the potential energy surfaces (PES) of the S0 and S1 states and of the absorption and emission maxima.

Modulating optical and electrical properties of chemically synthesized ZnMn2O4 nanoparticles through crystallinity: Integrating theoretical and experimental insights

Theoretical and experimental analyses of zinc manganite (ZnMn2O4) nanoparticles were carefully conducted for in-depth exploration of their electronic and optical properties. Nanosized particles, approximately 11–15 nm in size, were synthesized using a post-sintering assisted co-precipitation method. Theoretical calculations using Rietveld refinement were conducted to accurately predict crystal parameters and simulate XRD patterns consistent with experimental XRD observations. UV–visible absorption spectra and Tauc plot analysis indicated a bandgap ranging from 0.65 to 0.79 eV, while photoluminescence spectra revealed the most intense peak at 466 nm, possibly arising from exciton recombination processes or defect-related emissions. Density function theory (DFT) calculations were employed to compute the band structure and density of states of ZnMn2O4, resulting in a calculated bandgap of 0.73 eV, which aligned closely with the experimental findings. Moreover, DFT calculation identified atomic-level transitions responsible for absorption peaks in the material. Comprehensive evaluations of the mechanical and optical properties, integrating theoretical insights with experimental data, provided a holistic understanding of the intricate electronic and optical characteristics of ZnMn2O4. Furthermore, frequency and temperature-dependent dielectric properties demonstrated the MWS-type polarization effect. Besides, the activation energy of 0.582–0.553 eV, calculated using the Arrhenius plot, was good in accordance with our dielectric analysis, solidifying the potential of this nanomaterial for advanced optoelectronic applications.

Physical, optical, spectroscopic features of Li2B4O7-Bi2O3-Sb2O3 glass system reinforced with molybdenum ions

To comprehend the physical, optical and spectroscopic properties of a novel multicomponent glass system with compositional formula 60Li2B4O7-30Bi2O3-(10-x)Sb2O3-xMoO3 (x = 0, 2.5, 5, 7.5 and 10 mol%) has been synthesized by melt quench process. The lack of intense peaks in the XRD confirmed the glassy nature of the prepared samples. On Substitution of Sb2O3 with MoO3 in lithium tetraborate-bismuthate glasses, a linear decrease in the density and an increase in the molar volume has been noticed. Physical parameters like oxygen packing density, oxygen molar volume and packing density have been computed. Optical energy bandgap evaluated from UV–Visible absorption spectra, declined with increase of MoO3. Refractive indices exhibited opposite trend with optical energy bandgap and opens applications for non-linear optical devices. Vibrational modes in the as-prepared glasses have been identified by FTIR and Raman spectra. With increase in MoO3 content, Mo6+ ions transformed to Mo5+ units which in turn converted BO4 to BO3 units as confirmed by FTIR and Raman spectroscopies.

Flexible poly (ethylene-co-vinyl acetate)/copper oxide nanocomposites: A promising avenue for energy storage applications

The use of metal oxide nanoparticles in polymeric materials to improve optical properties, dielectric constant, mechanical strength, and electrical conductivity has generated significant interest in fabricating flexible optoelectronic and energy storage devices. Herein, copper oxide (CuO) nanoparticle-reinforced poly (ethylene-co-vinyl acetate) (EVA) nanocomposites were prepared using a solvent-free two roll mill mixing method. Fourier transform infrared (FTIR) analysis reveals the distinct absorption peaks of CuO in the EVA matrix. The addition of CuO nanoparticles improved the crystallinity of EVA, as confirmed by X-ray diffraction (XRD). The addition of CuO to EVA led to an increase in the refractive index and a decrease in bandgap energy, as well as a broadening and intensification of UV–visible absorption, indicating strong interactions between CuO nanoparticles and the EVA matrix. Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) revealed a homogeneous dispersion of CuO nanoparticles throughout the EVA matrix. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) demonstrated that the incorporation of CuO nanoparticles into EVA significantly enhanced its thermal properties. The electrical characteristics studies showed that the AC conductivity and dielectric constant of EVA increased significantly with increasing temperatures and CuO nanoparticle loading levels. EVA containing 5 wt% CuO exhibited the highest conductivity and the lowest activation energy. CuO nanoparticle reinforcement significantly enhanced the tensile, tear, and impact strength of EVA while reducing elongation at break up to a particular concentration. The nanocomposites containing 5 wt% CuO exhibited the highest tensile, tear resistance, and impact strengths, outperforming virgin EVA by 85 %, 103.6 %, and 83.16 %, respectively. These findings suggest that EVA/CuO nanocomposites are promising candidates for flexible dielectric materials.

Influences of hydrogen-bond promoting hydroxyl group on photophysical and catalytic properties of lanthanide pyridine dicarboxylate frameworks

To study the influences of hydrogen bonding interactions on photophysical properties and catalytic activities with insignificant interference from structural disparity, two new isostructural [LnIII2(OH-pda)(ox)2(H2O)4]∙4H2O coordination polymers (LnIII = EuIII (I) and NdIII (IIa), OH–H2pda = 4-hydroxypyridine-2,6-dicarboxylic acid, H2ox = oxalic acid) were synthesized and characterized. They are also isostructural to [NdIII2(pda)(ox)2(H2O)4]∙4H2O (IIb), H2pda = pyridine-2,6-dicarboxylic acid) containing pda2− instead of OH-pda2-. The identical framework structure of IIa and IIb with additional hydrogen bonding interactions in IIa due to –OH group of OH-pda2- has been presented. Based on IIa and IIb, the effects of the –OH group on photophysical properties and catalytic activities were then investigated without structural bias. With reference to the UV–vis absorption and phosphorescent emission spectroscopy, the singlet (S1) and triplet (T1) state energies of OH–H2pda (41,600 and 19,200 cm−1), H2pda (48,200 and 23,300 cm−1), OH-pda2- (IIa, 41,400 and 22,500 cm−1) and pda2− (IIb, 47,100 and 23,300 cm−1) were determined from which the influences of the –OH group have been revealed. Important roles of the –OH group as electron-donating group as well as hydrogen bond promoter have been proposed. Catalytic activities of IIa and IIb were comparatively examined using the solvent-free CO2 cycloaddition reaction at atmospheric pressure with epichlorohydrin in the presence of tetrabutylammonium bromide. The inferior performance of IIa (maximum yield of 62(±2)%) to IIb (maximum yield of 68(±2)%) was unexpectedly disclosed and the drawback of the substantial involvement of the catalytic sites in hydrogen bonding interactions has been demonstrated. Their reusability was additionally explored.

Integrating atmospheric water harvester with hydrovoltaics: Simultaneous freshwater production and power generation

Integration of an atmospheric water harvester (AWH) with hydrovoltaic (HV) technology poking a new technology and notification to the arid region people to harvest freshwater and electricity simultaneously from the humid atmosphere even in the non-water region. In this work, we have fabricated a composite material by attaching the sulfonic groups to the graphitic oxide substrate (SGhO) through a one-step reflux method. The material delivers an excellent water absorbing ability of 0.3 g g−1h−1and 2 g g−1in 19 h under a 40–60 % humid environment. The electrical experiments show during moisture absorption, a specific voltage and current are generated indicating the dissociation of sulfonic groups in the graphitic structure creates a drift movement of H+ions through the composite. Our device delivers a voltage of 0.25 V and a high current of 160 µA from a single device during moisture movements through the structure under the relative humidity of 60–65 %. The rapid enhancement of the interfacial temperature from 31 °C to 44 °C within a minute due to the presence of graphitic oxide shows excellent photothermal capacity for the light-induced evaporation mechanism and collecting the condensed water as freshwater. The composite can evaporate all absorbed water within 0.5 h in one sun illumination (1 kW/m2) under the ambient relative humidity (RH) of 40–60 %. Several trials of washing treatments were done to ensure the chemical bonding of sulfonic groups into the graphitic structure. Therefore, it was confirmed the excellent stability, and repeatability for repeatable practical applications. Furthermore, the purity of the collected water is conducted with various analyses such as pH, TDS, and UV–Vis absorption studies and confirmed the excellent purified water which highly meets the global drinking water standards. Therefore, this work demonstrates a single way to achieve dual goals such as water harvesting as well as power generation for a better tomorrow.

Facile Design of Bi2S3‐Doped CeO2/Dihydroxybenzoate Composite as Highly Efficient UV‐Shielding Agents

AbstractIn this study, bismuth sulfide (Bi2S3)‐doped cerium oxide (CeO2) was prepared via hydrothermal method, and by depositing ethyl 3,4‐dihydroxybenzoate (EDHB) on the surface of Bi2S3/CeO2 (Bi2S3/CeO2/EDHB and BCE). The samples were characterized by FTIR, XRD, TEM, and UV–vis absorption spectrum means. According to the characterizations, Bi2S3 was successfully incorporated into the CeO2 structure (Bi2S3/CeO2), and the prepared BCE/PVC composite films display excellent UV‐shielding property. Moreover, the result of thermogravimetric analysis (TGA) tests indicated that BCE also was barely catalytic thermal decomposition of PVC matrix. This work not only paves an attractive way for the design of the CeO2‐based UV‐shielding agent, but also provides valuable insights into the inspiration to construct high‐performance UV‐shielding composites.

Fluorescence and colorimetric dual-mode sensing of copper ions and fingerprint visualization by benzimidazole derivatives

In this paper, the molecular fluorescence probe H containing an imidazole structure was designed and synthesized by forming a ring between two amino groups and one aldehyde group. The synthesized probe H exhibits a Stokes shift of 144 nm with fluorescence emission at 555 nm and excitation at 411 nm. The fluorescence of probe H was quenched by the addition of Cu2+ and accompanied a red-shift of ultraviolet–visible (UV–Vis) absorption spectrum. Probe H reveals good selectivity and high sensitivity to Cu2+ in the fluorescence and UV–Vis absorption spectrum. And the limit of detection (LOD) for Cu2+ by fluorescence and UV–Vis spectrum methods were 0.14 nmol L−1 and 1.34 μmol L−1, respectively. The binding ratio of probe H and Cu2+ is 1:1 according to the Job’s plot equation. High resolution mass spectrometry (HRMS) and density function theory (DFT) calculations proved that the solvent acetonitrile and anionic chloride ion participated in the formation of H-Cu2+ complex. Furthermore, the established fluorescence analytical method was successfully applied for the detection of Cu2+ and spiked recovery experiments in tap water and mineral water. In addition, the probe exhibited outstanding solid-state fluorescence because of its excellently planar structure, and displayed a secondary fingerprint structure in the application of fingerprint detection.

A pH visual sensing platform based on dual-emission chiral carbon dots for discrimination of normal/cancer cells and monitoring food freshness

Accurate detection of pH is important in pathological processes and food freshness. Developing sensors of sensitive response and visualization for pH is highly demanded. In this work, Chiral carbon dots(CCDs) was synthesized via one-pot hydrothermal process using o-phenylenediamine and L-Tryptophan, which displayed circular dichroism (CD) signals at 200–255 nm and 255–300 nm. The CCDs exhibited dual-emission peaks with blue and red emission bands when excited at 360 nm. The ratiometric signals of UV–vis absorption and fluorescence intensity of L-CDs were responsive over the pH range of 2.0 to 11.0 with significant color changes in solution. Fluorescence imaging of live cells displayed different signals related to pH in both the blue and red channels, allowing accurate measurement of the pH of the cellular environment. Furthermore, the pH test paper based on L-CDs enabled monitoring the freshness of shrimp and pork under 365 nm UV light. Therefore, L-CDs provided a multifunctional visual pH sensing platform for environmental monitoring and biosensing.

Effect of replacing B2O3 with CuO on the structural, optical absorption, thermal, mechanical, and gamma-ray shielding properties of B2O3–Bi2O3–K2O glass

This paper delves into the effect of replacing B2O3 with CuO on the structural, optical absorption, thermal, mechanical, and gamma(γ)-ray shielding properties of four CKB glasses formulated as (65-y)B2O3–15Bi2O3–20K2O-yCuO (where y = 0, 0.3, 0.6, and 1.2 mol%). The glasses were created using the melt-quenching technique, and their non-crystalline structure was verified by X-ray diffraction (XRD) analysis. Fourier-transform infrared (FTIR) spectroscopy identified several structural groups, predominantly consisting of BO3, BO4 units, and B–O–B linkages. Thermal properties, assessed via Differential Scanning Calorimetry (DSC), indicated that the glass transition temperature was highest for the 0.3 mol% CuO sample (CKB0.3), demonstrating enhanced thermal stability in comparison to other compositions. Density measurements correlated positively with CuO concentration, peaking at 1.2 mol%, while molar volume, boron molar volume, oxygen packing density, and boron-boron separation distances showed a decreasing trend with increased CuO concentration. UV–Vis absorption spectroscopy indicated a decline in the optical energy gap and an increase in Urbach energy, attributed to the conversion of BO3 into BO4 units in the glass matrix. Mechanical properties, evaluated using the Makishima-Mackenzie model, demonstrated enhancements in elastic moduli and micro-hardness with rising CuO concentration. The γ-ray shielding properties (γ-RPs) were examined at energies of 0.662, 1.173, and 1.333 MeV, revealing that both the linear attenuation coefficient and effective atomic number reached their maximum values at 1.2 mol% CuO (CKB1.2). While CKB1.2 exhibited excellent mechanical and γ-ray shielding performance, CKB0.3 excelled in thermal stability and demonstrated γ-ray shielding efficiency comparable to CKB1.2. This suggests that CKB0.3 is a promising candidate for radiation shielding applications requiring a balanced combination of thermal stability and effective γ-ray attenuation properties, particularly at 0.662 MeV.