Journal of Fluorescence最新文献

Novel luminescent N₃O₃-donor Sm(III) macrocyclic complex i.e., [Sm(C₁₇H₂₅N₃O₅)].3NO₃; [(2Z,17Z)-7,10,13-trioxa-3,17-diaza-1(2,6)-pyridinacycloocta-decaphane-2,17-diene-2,18-diol] has been synthesized through the template synthetic route by using 1,13-diamino-4,7,10-trioxatridacane and pyridine-2,6-dicarboxylic acid ligand precursors in the presence of Sm(NO₃)₃.6H₂O in (1:1:1) molar ratios. Elemental analysis, ¹H NMR, ¹³C NMR, UV-Vis, FTIR, XRD, and mass spectrometry techniques have been utilized for the characterization of the synthesized complex. The crystalline nature of the complex is confirmed by the existence of sharp narrow peaks in the X-ray diffractogram. Optical property (Photoluminescence) is analyzed by PL-spectroscopy and results manifested that under 272 nm excitation wavelength, the complex exhibited three characteristic emission peaks at 563 nm, 602 nm, and 644 nm corresponded to the ⁴G_5/2→⁶H_5/2, ⁴G_5/2→⁶H_7/2, and ⁴G_5/2→⁶H_9/2 transitions respectively. This property leads the use of this reported complex as an optical active material which could be used as sensor for analysis and detection purpose such as cell or tissue imaging, solar cell, luminescent probe etc. Antimicrobial screening of the complex against E. coli, & S. aureus bacterial strains and Alternaria alternate & Fusarium solani fungal strains has also been performed to investigate their antimicrobial potential and revealed satisfactory results. Antioxidant potential of the complex has been checked by applying a DPPH free radical scavenging assay and the complex appeared with notable result. Cyclic voltammetry results indicated the electrochemical nature of the complex as prominent redox material for redox reactions.

A high-performance ratiometric fluorescence pH sensor based on HPTS-IP/TiO₂@THHM pH sensing film which contains a pH sensing layer and a scattering layer was developed. The pH sensing layer and scattering layer were fabricated by embedding HPTS-IP hydrophobic ion pairs and TiO₂ in TEOS-HTES organic/inorganic hybrid matrix (THHM), respectively. The HPTS-IP hydrophobic ion pairs were excited using pulsed signals from two LEDs with emission peaks of 404 nm and 454 nm, respectively. The fluorescence intensity ratio ([Formula: see text]) was significantly correlated with pH and exhibited excellent performance within the pH range of 6.0 ~ 9.0. Based on fluorescence intensity, peak position, peak width and spectral shape characteristics, a support vector regression (SVR) model was established for predicting the pH value. The root mean square error (RMSE) of the validation dataset in leave-one-out cross-validation (LOOCV) method was 0.180 and the correlation coefficient (R) of the predicted pH versus experimental pH reached as high as 0.999. The sensor exhibited fast response with a response time of 27 s, excellent reproducibility, reversibility and stability.

In healthcare, bacterial infections always remain a critical challenge. In this study, pristine and Ag-TiO₂ nanofibers (NFs) with varying silver (Ag) concentration (2wt.%, 4wt.%, 6wt.% and 8wt.%) were prepared by electrospinning, followed by calcination at 500 °C for 3 h. Morphological characterization revealed the formation of one-dimensional NFs with mean diameter 83.06 to 25.80 nm, depending on the Ag loading. The antibacterial activities were investigated using conventional methods (well diffusion, colony forming units counting) and advanced techniques (Confocal laser scanning fluorescence microscopy, Scanning electron microscopy and Fluorescence spectroscopy). The results from antibacterial studies have revealed that sample with 8wt.% Ag-TiO₂ exhibited the most significant antibacterial effect as evidenced by marked reduction in CFUs, almost complete quenching of fluorescence emission intensity and perforated bacterial membranes and cellular debris.

This study presents a rapid, green, and highly sensitive fluorescence-based method for detecting urea in soil using nitrogen-doped carbon dots (CDs) synthesized via a microwave-assisted process. Citric acid and urea were used as carbon and nitrogen precursors, respectively, with optimal synthesis achieved at a 1:1 weight ratio and 9 min of microwave irradiation. The structural properties of nitrogen-doped carbon dots (CDs) were studied using X-ray Diffraction (XRD). Transmission Electron Microscopy (TEM) technique was used to observe the shape and size of the CDs, providing insight into their morphology. To understand the chemical composition, bonding states, and surface functionalities, X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) analyses were carried out. The performance of the nitrogen-doped-CDs in detecting urea, including their sensitivity and selectivity, was evaluated using fluorescence spectroscopy. The resulting CDs exhibited enhanced fluorescence properties and a limit of detection (LOD) as low as 143 mg/gm. The method demonstrated high selectivity toward urea even in the presence of interfering metal ions, and its effectiveness was validated in soil samples under varying pH conditions. This approach provides a cost-effective, scalable, and environmentally friendly solution for real-time monitoring of soil nutrients, supporting sustainable agricultural practices through improved nitrogen management.

The fluorescence and absorption characteristics of coumarin 1-(4-nitro-phenoxymethyl)-benzo[f]-chromen-3-one (4NPMB) at room temperature are examined in a mixture of acetonitrile (ACN) and tetrahydrofuran (THF) as well as in a few pure organic solvents. The influence of pure liquids on spectral characteristics is examined using various theories. Ground and excited state electric dipole moments were computed employing theoretical and Solvatochromic approaches. The redshift and excited electric dipole moment value of a molecule indicates that the molecule has gone through the intermolecular charge transfer (ICT). Kamlet-Taft suggests that the 4NPMB molecule integrates the solvent by its hydrogen bonding parameter rather than the dielectric parameter. From Catalan linear regression, we found that solvent acidity (SA) and the polarizability (SP) of a solvent have much more influence compared to solvent basicity (SB) and di-polarity (SdP) on a molecule. According to the preferential solvation investigation, tetrahydrofuran dominates the system up to the bulk molar fraction of 0.31. Acetonitrile thereafter takes over, as shown by the value of the preferential solvation constant ( $M_{12})$ . Fluorescence quenching of physiologically active fluorescent probe examined by using aniline as a quencher in various solvents. According to the fluorescence quenching investigation, the Stern-Volmer plot in solvents with varying dielectric constants exhibits a linear dependency, revealing that quenching responses are dynamic in nature. Different types of quenching associated with the reaction have been found, and their corresponding quenching parameters have been evaluated.

In this work, two Cu(II)-based coordination polymers, [Cu(oba)(bpta)]·(DMF)₂ (CP1) and [Cu(oba)(bpfb)]·(DMF)₂ (CP2), were synthesized via a mixed-ligand solvothermal method using 4,4'-oxybisbenzoic acid (H₂oba) and bis-pyridyl co-ligands. Both CPs exhibit strong solid-state fluorescence and excellent water stability. CP1 shows high selectivity for Fe³⁺ with a K_SV of 2.63 × 10⁵ M⁻¹ and LOD of 0.37 μmol·L⁻¹, while CP2 is highly sensitive to CrO₄²⁻ with a K_SV of 1.47 × 10⁵ M⁻¹ and LOD of 0.65 μmol·L⁻¹. Both materials demonstrate reversible fluorescence quenching over multiple cycles. These results indicate that CP1 and CP2 are promising luminescent probes for the sensitive and recyclable detection of environmentally hazardous ions, offering potential for real-time water quality monitoring.

Development of rapid and cost effective techniques for detecting metal ions is important to prevent water pollution and ensure public safety. Herein, we report the synthesis of fluorescent carbon dots (t-CDs) from waste egg tray paper pulp by one step hydrothermal treatment. The synthesized t-CDs have been characterized by various analytical techniques. The prepared t-CDs demonstrated excitation dependent emission and particle sizes ranges from 7 nm to 14 nm with mean diameter of 9 nm. Our study show that the fluorescence of the t-CDs is efficiently turn off upon addition of Fe³⁺ due to the formation of complex between Fe³⁺ and the surface functional groups of t-CDs which enables aggregation and electron transfer process, resulting in fluorescence quenching. There is a linear relationship between the fluorescence quenching of the t-CDs versus the concentration of the Fe³⁺ in the ranges, 0-40 µM with limit of detection of 1.418 µM. Further, the t-CDs is applied as sensor for detection of Fe³⁺ in real water samples, demonstrating its utility in environment monitoring.

Designing of fluorescent materials in biomedical sciences is gaining attention due to unique characteristics like imaging driven by diagnosis and treatment. The exploration of fluorescent materials from green sources with highlights its application arena in cancer theranostic gained significant attention of oncology researchers. Outwards to the bioimaging techniques, fluorescent graphene quantum dots (fGQDs) grasp a potential place in biomedical research. Additionally, fGQDs have tuneable surface characteristics with high fluorescence, high loading and permeation capability. The present investigation explored the green synthesis of fGQDs using star anise fruit as precursor followed by surface decorated hyaluronic acid (HA) to form conjugated HA - GQD. The advance spectral characterization was used to confirm the synthesis of fGQDs and HA-GQD. The emission at 338 nm with excitation at 576 nm promise strong fluorescence with quantum yield of 16.52%. The conjugated HA-GQDs shows prominent bioimaging capability and lower cytotoxic potential at concentration less than 40 µg/ml. While cell inhibition against MCF-7 was dramatically increases at concentration above 100 µg/mL suitable to promote synergistic inhibition with other anticancer agents. This work demonstrates a sustainable route for developing multifunctional nanomaterials with promising application in cancer theranostics.

In the present study, we employed a comprehensive multi-step synthetic methodology to design and develop two novel organic dyes, TP-CLN and PT-CLN, using sydnone as a synthon. These compounds feature a donor-π-acceptor (D-π-A) architecture and are classified as chalcones. The resulting molecules were intricately attached to one-dimensional cadmium sulfide nanowires (1D CdS NWs), functioning as highly efficient light energy harvesters for dye-sensitized solar cells (DSSCs). The process of anchoring the dye onto the nano-network of CdS NWs was accomplished using simple solution chemistry, which proved to be both straightforward and efficient. We assessed the sensitizing capabilities of the synthesized materials through various methods, including optical and electrochemical investigations, density functional theory (DFT) simulations, and comprehensive photovoltaic assessments. A detailed analysis of the Dye-Sensitized Solar Cells containing PT-CLN revealed a photovoltaic efficiency 3.35 times higher (0.342%) than that of bare CdS NWs (0.102%) under standard light illumination. Similarly, the use of TP-CLN demonstrated a significant 3.08-fold improvement (0.314%) in photovoltaic efficiency. These results not only provide strong empirical support for the enhancement of external quantum efficiency (EQE) but also show a remarkable consistency with findings from optical examinations.

Carbon Quantum Dots (CQDs), a new class of 0D carbon-based nanomaterials, have garnered significant interest due to their exceptional physicochemical properties, including high photoluminescence, excellent biocompatibility, chemical stability, and low cytotoxicity. This review provides a comprehensive overview of recent advances in CQD synthesis strategies, ranging from top-down approaches such as arc discharge, electrochemical oxidation, and laser ablation to bottom-up techniques like hydrothermal, solvothermal, microwave-assisted, and thermal decomposition methods. Special emphasis is placed on green synthesis routes employing natural precursors, aligning with sustainable nanotechnology goals. The influence of heteroatom doping and surface functionalization on the electronic and optical properties of CQDs is systematically discussed. Furthermore, we elucidate the role of CQDs as efficient components in photocatalysis, photovoltaics, sensing, and drug delivery, highlighting their integration into perovskite and organic solar cells, as well as their applicability in advanced biosensors and targeted drug delivery systems. The review also explores various characterization techniques such as UV-Vis, PL, TEM, FTIR, XRD, and Raman spectroscopy, critical for understanding CQD structure property relationships. Overall, this work distills current insights and future prospects of CQDs, underscoring their transformative potential across environmental, energy, and biomedical domains.