Journal of Fluorescence最新文献

This study reveals the solvent dependent third-order nonlinear optical (NLO) features of malachite green (MG) dye using Z-scan technique. MG dye is dissolved in polar solvents, including DMF, DMSO, ethanol, acetone, methanol, and 1-propanol. The study employs the Z-scan instrument, using a continuous wave (CW) laser as the excitation source, operating at a wavelength of 650 nm. The closed aperture (CA) and open aperture (OA) Z-scan techniques are used to assess the nonlinear indices of refraction (n₂) and nonlinear coefficient of absorption (β) of MG dye. MG dye demonstrates both saturable absorption (SA) and reverse saturable absorption (RSA) in the OA Z-scan results, due to negative and positive NLO absorption coefficients. MG dye proves a self-defocusing NLO refractive index while operating under low-power conditions. The third-order NLO susceptibility (χ³) of MG dye in various liquids are calculated to be the order of 10^-6 esu. Multilinear regression fit is applied here to investigate the various intermolecular interactions between the solute and solvent. MG dye exhibited large thermo-optic coefficient of the order of 10^- 3 K^- 1 is observed. The results give important new information about the characteristics of MG dye and indicate potential sources of material for NLO applications in future.

Fluorescent probes to detect biologically important acetate ion (AcO^-) are essential for regulating substance metabolism, alleviating inflammatory symptoms, reducing cancer incidence, and diagnosing early diseases. However, the relatively small charge-to-atomic radius ratio in AcO^- and its triangular spatial structure pose challenges in recognition and often lead to interference from other anions in detection methods. Herein, we introduce a quinoxaline fluorescent probe, o-(4-(2-(3-oxo-3,4 -dihydroqui-noxalin-2-yl)vinyl)phenyl) dimethylaminothiophene ester (QPDMT), specifically design and synthetic for the accurate detection of AcO^-. This probe leverages molecular nucleophilicity and electron transfer to undergo a reaction that releases the fluorophore upon cleavage of the thioformyl ether bond, exhibiting a turn-on fluorescence response at 530 nm. QPDMT exhibits an impressively low detection limit of 30 nM, a rapid response time of 20 min, a robust linear response in the 1-9 µM range and excellent fluorescence quantum yield, 0.32. Importantly, this probe demonstrates low cytotoxicity, making it an ideal candidate for endogenous AcO^- detection in living cells and organisms.

The capability of conventional fluorescence spectroscopy and right-angled synchronous fluorescence spectroscopy (SFS) was evaluated to quantify the antibacterial potential of chemically synthesized Tryptophan coordinated silver nanoparticles (Ag-TrpNPs). Silver nanoparticles have gained significant importance as a material of interest due to their diverse assemblies in the nanoscale range and their potent antibacterial activity. But due to toxicity of silver nanoparticles there is a dire need to coordinate these materials with some biocompatible and biodegradable molecules. The study has been focused on chemical synthesis of functional fluorescence nanomaterials based on Tryptophan molecules coordinated with silver nanoparticles (Ag-TrpNPs). The antibacterial activity of Ag-TrpNPs was assessed in bacteria due to their functional characteristics such as tuneability, biocompatibility, and bioavailability. We employed optical characterization techniques such as Ultraviolet-visible spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), fluorescence spectroscopy, and confocal microscopy to ensure the particles formation in aqueous suspension. DLS analysis confirmed the hydrodynamic size of the nanoparticles of approximately 100 nm. SEM images revealed the spherical morphology and size distribution of the Ag-TrpNPs. Escherichia coli bacterial strains were used to assess the antibacterial efficacy of the Ag-TrpNPs using fluorescence spectroscopy and imaging. Initially, the agar well plate method was employed to evaluate the antimicrobial activity of the Ag-TrpNPs. The significant zones of inhibition of size 37 mm at 500 µg/mL and 27 mm at 15.5 µg/mL were reported which indicated the efficiency of Ag-TrpNPs from higher to lower concentration. Conventional and synchronous fluorescence spectra provided evidence of bacterial cell death in aqueous suspensions to ensure the interaction of Ag-TrpNPs with E. coli bacteria at different times and concentrations. SEM was employed to investigate the interaction mechanism between Ag-TrpNPs and bacterial cells. The images revealed cell wall disintegration, leading to the leakage of cellular contents, and eventually cell death occurred.

The suggested study follows specific protocols to guarantee that the atomoxetine drug analysis approach is environmentally friendly and sustainable. A number of recently created methods were used as prospective evidence for environmental sustainability and applicability, which is an essential point to emphasize. The current study introduces a new and very unique technology using ultrasensitive spectrofluorimetry to identify the atomoxetine (AXT) medication. A one-step, one-pot, direct spectrofluorimetric technique was used in this study's methodology, which was determined to be effective and environmentally sustainable for the drug's evaluation and validation. When AXT and EY reagent were mixed in an acidic setting, a highly resonant Rayleigh scattering product was promptly generated. The application of fluorimetric analysis was built on a novel theory that the augmentation in dye response subsequent to the addition of AXT was directly correlated to the resultant complex's molecular mass, as determined at a wavelength of 365 nm. The complexation progression caused a considerable rise in the molecular mass, from 292.82 (AXT⁺) to 983.68 (AXT-EY) g mol^-1. The quantum yield for the coupled product was measured. The linearity was determined to be between 30 and 1500 ng mL^-1, while the sensitivity values were found to be between 9.2 and 28.1 ng mL^-1. Analyzing AXT-EY complexes allowed us to determine the best values for all of the system's adjustable parameters. The system showed adherence to International Council for Harmonization (ICH) criteria without difficulties. The recommended procedure was then evaluated for environmental friendliness using many current environmental safety metrics. Fortunately, the current analytical technique is also recognized as a white one by the WAC standards, which integrate functional and ecological features using the Green/Red/Blue (RGB 12) design. A novel instrument called BAGI was used to assess the feasibility of the proposed approach in the field of analytical chemistry.

Luminophors of α-Naphthol doped with varying concentrations of anthracene and perylene were prepared by conventional solid state reaction method to explore its fluorescence characteristics. The fluorescence spectra of bicomponent and tricomponent luminophors reveals the fluorescence excitation energy transfer (FRET) process. The prepared bi and tri component luminophors were excited at 290 nm which corresponds to host excitation wavelength. The weak violet fluorescence of host, α-Naphthol, gets quenched and give anthracene like emission in bicomponent luminophor systems. Further doping with second host, perylene, in anthracene containing α-Naphthol luminophors, red shifted emission was observed at 605 nm. The structural parameters, thermal stability and electrical properties of doped luminophors were studied by using X-ray diffraction, TGA-DSC and Cyclic Voltammetry respectively. The particle size of the prepared luminophors was confirmed by scanning electron microscopy (SEM).

The synthesis of rhodamine dyes (R6G and R1010) and their fluorescence characterization within polymer-based microfluidics, offers an exciting and novel approach in materials science and chemical analysis. This work investigates the emission of polycarbonate substrates (PC) by UV-visible. The ablation threshold (16mj.sec^-1) of PC at 193nm wavelength after that ablation process continued to produce microfluidic serpentine channels on PC by using G-Code. The fluorescence characteristics of Rhodamine 6G and Rhodamine 101 are investigated. Absorption and emission at peak wavelength were analyzed against R6G and R101 concentrations. Furthermore, the refractive indices of both R6G and R101 vis concentrations are examined. As a result at low concentrations, there was the highest overlapping, and at high concentrations, there was the smallest overlapping. R101 showed better photostability and a more consistent diffusion, whereas R6G had a faster diffusion and stronger fluorescence intensity. These differences were caused by the different molecular structures of the dyes and their interactions with the PC microchannel. Incorporating R6G and R101 dyes into a polycarbonate PC microfluidic chip would enhances both the resolution and sensitivity of fluorescence detection. The limited microfluidic setup facilitates ultra-high-resolution investigation and minimizing sample volumes, making it suitable for applications requiring precise measurements. The innovation relies on the utilization of the unique fluorescence characteristics of R6G (Rhodamine 6G) and R101 (Rhodamine 101) dyes to enhance the performance of polycarbonate microfluidic devices. R6G has high fluorescence quantum yield and stability, rendering it suitable for sensitive detection, while R101 offers superior brightness and improved resistance to photobleaching. Incorporation of these dyes into polymeric microfluidics improves sensitivity and facilitates real-time, dynamic sample analysis. This method offers a portable, economical solution with high-throughput capabilities, greatly enhancing both analytical and process accuracy across a variety of applications.

Aromatic difluoroboron β-ketoiminate complexes (ketimBF₂) are structural nitrogen-containing analogues of aromatic difluoroboron β-diketonates (diketBF₂). Aggregation-induced emission (AIE) and polymorphic behavior allow ketimBF₂ to exhibit mechanofluorochromic (MFC) properties. A detailed comparative study of the luminescence of a wide range of ketimBF₂ with H- and CH₃-substituents of nitrogen atom and diketBF₂ with various substituents of the chelate ring (methyl, phenyl, toluoyl, anisoyl, biphenyl, naphthyl, anthracyl) in the solid state was carried out. As a result, regularities of the influence of substituents on the luminescent and MFC properties for 21 dyes have been established. Replacing one oxygen atom in diketBF₂ with nitrogen atom in the chelate ring (H-substituted ketimBF₂) changes the nature of the molecular stacking in crystals, which is manifested in different MFC properties. The introduction of a methyl group into the chelate ring (CH₃-substituted ketimBF₂) induces steric hindrance, which prevents the efficient formation of supramolecular structures and, consequently, leads to the shortest-wavelength monomeric emission in the solid state in comparison with oxygen and H-substituted nitrogen analogues. Methoxy derivative of H-substituted ketimBF₂ exhibits non-reversible fluorochromic switching after annealing and can be used as temperature indicator to control unauthorized heating of temperature-sensitive substances during transportation and storage.

This study presents the development of a sensitive and selective gold ion (Au³⁺) sensor utilizing layer-by-layer (LbL) assembled thin films composed of polyethylenimine (PEI) and poly (acrylic acid) (PAA) conjugated with rhodamine (Rho). The first study revealed that the polymeric sensors (PAA-Rho) demonstrated significant selectivity and sensitivity in their colorimetric and fluorescence responses to Au³⁺ compared to other metal ions. In their spirolactam form, the polymeric sensors were non-fluorescent but could selectively transform into the fluorescent ring-opened amide form upon interaction with Au³⁺ ions, resulting in fluorescence enhancement and observable color changes. Common co-existing metal ions showed negligible interference in the detection of Au³⁺. The LbL sensor exhibited a linear increase in absorbance with the addition of bilayers, confirming successful film deposition. Surface morphology analysis using SEM, along with structural confirmation via ATR-FTIR and XRD, further validated the sensor's capability to detect cation. Results demonstrated that the LbL sensor exhibited selectivity for Au³⁺ ions within the range 1 × 10^-6 to 1 × 10^-3 M. This approach offers an easily understandable and intrinsically sensitive means for detecting Au³⁺ ions in both environmental and biological applications.

Two novel Tb(III) ternary complexes, [Tb₂(Phen)₂(p-BrBA)₆] and [TbY(Phen)₂(p-BrBA)₆], have been synthesized with p-bromobenzoic acid(p-BrBA) as the primary ligand and 1,10-phenanthroline(Phen) as the secondary ligand. The structures of these complexes are characterized by elemental analysis, IR spectroscopy, UV-vis absorption spectroscopy, thermal analysis (TGA) and single-crystal X-ray diffraction. The crystal structures of the compounds are similar because of similar radii of Tb³⁺ ion and Y³⁺ ion. Both the homobimetallic single crystal and the heterobimetallic single crystal belong to the monoclinic system. The results show that both complexes have excellent luminescence properties, including luminescent intensity, luminescent lifetime and quantum yield. The two compounds have an excited state lifetime of milliseconds and the photoluminescence quantum efficiencies of the two terbium complexes can exceed 100% upon excitation to their 5d states in theory, which is attributed to luminescent lifetime and quantum cutting (QC). Furthermore, the luminescent properties of [TbY(Phen)₂(p-BrBA)₆] are actually superior to those of [Tb₂(Phen)₂(p-BrBA)₆].

A carbazole-based fluorescent probe YCN with AIE performance and a large Stokes shift (242 nm) shift was synthesized by attaching 4-acetonitrile pyridine to the 3-phenylaldehyde butylcarbazole. Its structure was characterized by ¹H NMR, ¹³C NMR and MS. Probe YCN has high selectivity and sensitivity toward ONOO^-. The addition of ONOO^- to the probe YCN solution results in a noticeable color change from pale yellow to colorless under natural light, and a fluorescent color change from bright orange-yellow to bright yellow-green under a 365 nm UV lamp, which can be distinguished by the naked eye. The research results on the reaction mechanism showed that when YCN reacted with ONOO^-, -C = C- was oxidized and broken into -CHO, and the ICT effect was significantly inhibited, resulting in changes in UV absorption and fluorescence emission phenomenon. The recognition mechanism was verified by ¹H NMR, mass spectrometry (MS) and density function theory (DFT) calculations. The experiments of live cells imaging suggested that compound YCN can be used as a fluorescent probe for the detection of ONOO^- in HeLa cells. This result indicates that YCN has potential application prospects in the biological aspects.