Remarkable Luminescence Properties Research Articles

A postsynthetically modified MOF-808 as a fluorescent sensor for the detection of nitrofurazone antibiotic

The excessive use of nitrofuran drugs in human healthcare as well as in animal husbandry are a major threat to both the environment and human health. As a result, there is an urgent requirement for extensive research to develop materials that can efficiently detect these residual pollutants. However, developing sensor materials with high sensitivity, selectivity, and recyclability is still a challenging task. Herein, we design and synthesize a stable photoluminescent metal–organic framework (MOFs) named MOF-808-AAA, where we have first time integrated a fluorescent organic molecule, 3-anthracen-9-yl-acrylic acid (AAA), via solvent-assisted ligand exchange (SALE) method. Comprehensive structural characterization employing various techniques including PXRD, FT-IR spectra, N2 adsorption, 1H NMR, UV–Vis, and fluorescence spectra, confirmed the successful integration of AAA into the MOF-808 framework. The synthesized MOF-808-AAA demonstrates remarkable luminescence properties and exhibits quick sensitivity towards nitrofurazone (NFZ) with quenching constant (Ksv) of 2.98 × 104 M−1 and low detection limit of 0.51 µM in acetonitrile medium, demonstrating the efficacy of MOF-808-AAA as a promising fluorescent chemical sensor for NFZ detection. In addition, we have proposed a plausible turn off sensing mechanism based on photophysical and electrochemical studies.

Near-Unity Green Luminescent Hybrid Manganese Halides as X-ray Scintillators.

The increasing demands in optoelectronic applications have driven the advancement of organic-inorganic hybrid metal halides (OIMHs), owing to their exceptional optical and scintillation properties. Among them, zero-dimensional (0D) low-toxic manganese-based scintillators have garnered significant interest due to their exceptional optical transparency and elevated photoluminescence quantum yields (PLQYs), making them promising for colorful light-emitting diodes and X-ray imaging applications. In this study, two OIMH single crystals of (Br-PrTPP)2MnBr4 (Br-PrTPP = (3-bromopropyl) triphenylphosphonium) and (Br-BuTPP)2MnBr4 (Br-BuTPP = (4-bromobutyl) triphenylphosphonium) were prepared via a facile saturated crystallization method. Benefiting from the tetrahedrally coordinated [MnBr4]2- polyhedron, both of them exhibited strong green emissions peaked at 517 nm owing to the d-d electron transition of Mn2+ with near-unity PLQYs of 99.33 and 86.85%, respectively. Moreover, benefiting from the high optical transparencies and remarkable luminescence properties, these manganese halides also exhibit excellent radioluminescent performance with the highest light yield of up to 68,000 photons MeV-1, negligible afterglow (0.4 ms), and linear response to X-ray dose rate with the lowest detection limit of 45 nGyair s-1. In X-ray imaging, the flexible film made by the composite of (Br-PrTPP)2MnBr4 and PDMS shows an ultrahigh spatial resolution of 12.78 lp mm-1, which provides a potential visualization tool for X-ray radiography.

Photo-induced luminescence mechanism and the correlated defects characteristics in the sol-gel derived samarium ion substituted tin oxide (Sn1-xSmxO2) nanoparticles

Rare earth complexes have gained attention in recent years for their remarkable luminescence properties, especially their long lifetimes, clear emission bands, and significant luminous quantum efficiency. In the ultraviolet area, the lanthanide ions exhibit relatively tiny absorption. The current investigation systematically portrays the tailoring of the micro-structural, opto-electonic and defect related features of the sol-gel derived pristine and rare earth element-samarium (Sm3+) substituted tin oxide (SnO2) i.e., Sn1-xSmxO2 (x = 0.0, 0.1, 0.2 & 0.3) nanoparticles (NPs). The structural, optical, electronic, morphological, photo-induced luminescence and defects related characteristics of the NPs were explored as a function of samarium (Sm3+) substitution level. In-depth analysis of the structure-property correlation of the Sn1-xSmxO2 NPs is the goal of this study, focusing especially on the properties related to vacancy evolution and luminescence. The elemental mapping results revealed through energy dispersive X-ray spectroscopic (EDS) technique confirmed that the Sm-substitution is distributed uniformly throughout the NPs. The X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) studies corroborate that the Sm3+ substitution in the SnO2 matrix causes the decrease in crystallite size of the NPs and increase in the dislocation density. A monotonic increase in lattice strain has been observed using the Williamson – Hall (W – H) approach, which is in line with the NPs' increased dislocation density and decreased crystallite size with the Sm3+ substitution level. The presence of vacancy-type defects inside the NPs was demonstrated by positron annihilation lifetime (PAL) spectroscopic measurements, and a decrease in defects was noticed as the level of Sm3+ substitution increased. To explore the optical characteristics and the evolution of the energy band gap with Sm3+ substitution level, the optical absorption (OA) spectroscopic measurement was carried out. As the Sm-substitution level rises, the optical energy band gap of the substituted SnO2 NPs widens relative to that of pure SnO2 NPs. The existence of various absorbance bands corresponding to the atomic vibrations within the NPs were investigated by the Fourier-transform infrared (FT-IR) spectroscopic technique. The photo-induced fluorescence (FL) emission spectroscopic analysis evidenced that the defect density decreased as the Sm-substitution level increased, which is in accordance with the PAL spectroscopic studies. The FL spectra showed the two typical near band edge (NBE) and deep level emission (DLE) peaks of the NPs. The proportion of different defects and vacancies associated with the FL emission transitions are portrayed as Pie-chart diagrams. The tailored NPs can establish to be effective candidates for possible spintronic and optoelectronic applications including magneto-optical devices.

Synthesis and Optical Properties of Anion‐Responsive X‐shaped π‐Electronic System

AbstractThe properties of donor‐π‐acceptor molecules are strongly influenced by the electron density and configuration of both donor and acceptor moieties. In particular, X‐shaped molecules, where two linear π‐conjugation systems ended by donors and/or acceptors are crossed in their middle, are well‐known to separate frontier molecular orbitals, and the donor and acceptor strongly influence the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), respectively. A novel X‐shaped molecule, containing a diphenylamino group as the donor and a dimesitylboryl group as the acceptor, was synthesized to modulate the optical properties via anion complex formation. The X‐shaped molecule formed [1+1]‐ and [1+2]‐type anion complexes in solution, and a negative cooperative effect for the formation of the [1+2]‐type anion complex was observed. UV‐vis and fluorescence spectroscopy reveled the changes in the optical properties by the formation of anion complexes, with the spectral changes upon anion addition were consistent with the theoretical spectra obtained from time‐dependent density functional theory calculations. Furthermore, the X‐shaped molecule, which exhibits remarkable luminescence properties even in the solid state, demonstrated electroluminescent behavior.

Thiele's Fluorocarbons: Stable Diradicaloids with Efficient Visible-to-Near-Infrared Fluorescence from a Zwitterionic Excited State.

Thiele's hydrocarbon was the first synthesized diradicaloid in the search for stable open-shell structures, but it remains sensitive to oxygen and light. We here report the synthesis of Thiele's fluorocarbon (TFC) and its derivatives exhibiting exceptional thermal, oxidative, and photostability. TFCs have remarkable luminescent properties with yellow to NIR fluorescence and up to 100% quantum yields. X-ray crystallography and ESR spectroscopy confirm their closed-shell quinoidal ground state. As expected from their symmetric nonpolar structure, the TFCs' absorption spectra show no solvent effect, but their emission reveals an extraordinarily large Stokes shift which increases with solvent polarity (from 0.9 eV in cyclohexane to 1.5 eV in acetonitrile). We show that this behavior is a result of sudden polarization, leading to a zwitterionic excited state.

Pyrene-Fused Poly-Aromatic Regioisomers: Synthesis, Columnar Mesomorphism, and Optical Properties.

π-Extended pyrene compounds possess remarkable luminescent and semiconducting properties and are being intensively investigated as electroluminescent materials for potential uses in organic light-emitting diodes, transistors, and solar cells. Here, the synthesis of two sets of pyrene-containing π-conjugated polyaromatic regioisomers, namely 2,3,10,11,14,15,20,21-octaalkyloxypentabenzo[a,c,m,o,rst]pentaphene (BBPn) and 2,3,6,7,13,14,17,18-octaalkyloxydibenzo[j,tuv]phenanthro [9,10-b]picene (DBPn), is reported. They were obtained using the Suzuki-Miyaura cross-coupling in tandem with Scholl oxidative cyclodehydrogenation reactions from the easily accessible precursors 1,8- and 1,6-dibromopyrene, respectively. Both sets of compounds, equipped with eight peripheral aliphatic chains, self-assemble into a single hexagonal columnar mesophase, with one short-chain BBPn homolog also exhibiting another columnar mesophase at a lower temperature, with a rectangular symmetry; BBPn isomers also possess wider mesophase ranges and higher mesophases' stability than their DBPn homologs. These polycyclic aromatic hydrocarbons all show a strong tendency of face-on orientation on the substrate and could be controlled to edge-on alignment through mechanical shearing of interest for their implementation in photoelectronic devices. In addition, both series BBPn and DBPn display green-yellow luminescence, with high fluorescence quantum yields, around 30%. In particular, BBPn exhibit a blue shift phenomenon in both absorption and emission with respect to their DBPn isomers. DFT results were in good agreement with the optical properties and with the stability ranges of the mesophases by confirming the higher divergence from the flatness of DBPn compared with BBPn. Based on these interesting properties, these isomers could be potentially applied not only in the field of fluorescent dyes but also in the field of organic photoelectric semiconductor materials as electron transport materials.

Using a diphenyl-bi-(1,2,4-triazole) tricarbonylrhenium(I) complex with intramolecular π-π stacking interaction for efficient solid-state luminescence enhancement.

Since intramolecular π-π stacking interactions can modify the geometry, crystal packing mode, or even the electronic properties of transition metal complexes, they are also likely to influence the solid-state luminescence properties. Following this concept, a new tricarbonylrhenium(I) complex (Re-BPTA) was designed, based on a simple symmetrical 5,5'-dimethyl-4,4'-diphenyl-3,3'-bi-(1,2,4-triazole) organic ligand. The complex was prepared in good yield using a three-step procedure. The crystallographic study revealed that both phenyl rings are located on the same side of the molecule, and twisted by 71° and 62°, respectively, with respect to the bi-(1,2,4-triazole) unit. They overlap significantly, although they are slipped parallel to each other to minimize the intramolecular interaction energy. The π-π stacking interaction was also revealed by 1H NMR spectroscopy, in good agreement with the results of theoretical calculations. In organic solutions, a peculiar electrochemical signature was observed compared to closely-related pyridyl-triazole (pyta)-based complexes. With regard to the optical properties, the stiffness of the Re-BPTA complex led to the stabilization of the 3MLCT state, and thus to an enhancement of the red phosphorescence emission compared to the more flexible pyta complexes. However, an increased sensitivity to quenching by oxygen appeared. In the microcrystalline phase, the Re-BPTA complex showed strong photoluminescence (PL) emission in the green-yellow wavelength range (λPL = 548 nm, ΦPL = 0.52, 〈τPL〉 = 713 ns), and thus a dramatic solid-state luminescence enhancement (SLE) effect. These attractive emission properties can be attributed to the fact that the molecule undergoes little distortion between the ground state and the triplet excited state, as well as to a favorable intermolecular arrangement that minimizes detrimental interactions in the crystal lattice. The aggregation-induced phosphorescence emission (AIPE) effect was clear, with a 7-fold increase in emission intensity at 546 nm, although the aggregates formed in aqueous medium were much less emissive than the native microcrystalline powder. In this work, the rigidity of the Re-BPTA complex is reinforced by the intramolecular π-π stacking interaction of the phenyl rings. This original concept provides a rhenium tricarbonyl compound with very good SLE properties, and could be used more widely to successfully develop this area of research.

Pseudo-Tetrahedral Copper(I) Symmetrical Formamidine Dithiocarbamate-Phosphine Complexes: Antibacterial, Antioxidant and Pharmacokinetics Studies

Three copper(I) dithiocarbamate–phosphine complexes of the general formula Cu(PPh3)2L were synthesized by metathesis reactions of the potassium salt of the dithiocarbamate ligand L and the precursor complex Cu(PPh3)2NO3 in an equimolar ratio. L represents N,N′-bis(2,6-dimethylphenyl)formamidine dithiocarbamate L1 in complex 1, N,N′-bis(2,6-disopropylphenyl) formamidine dithiocarbamate L2 in complex 2, and N,N′-dimesitylformamidine dithiocarbamate L3 in complex 3. The single-crystal X-ray structure revealed the coordination of the copper atom to two sulfur atoms of the dithiocarbamates, as well as two phosphorus atoms of the PPh3 units, which resulted in distorted tetrahedral geometries. The calculated τ4 (tau factor) values for 1, 2 and 3 were 0.82, 0.81 and 0.85, respectively, confirming the pseudo-tetrahedral geometry proposed. Complexes 1–3 showed remarkable luminescent properties in CH2Cl2 at room temperature. All three complexes showed moderate-to-low antibacterial potential against Gram-negative bacteria, while none of the complexes were active against Gram-positive bacteria. The DPPH assay studies showed that complex 2 had the lowest IC50 (4.99 × 10−3 mM),and had higher DPPH free radical scavenging ability than 1 and 3. The pharmacological estimations of 1–3 showed that all of the complexes showed minimal violation of Lipinski’s rule.

Optical Properties of Transparent Rare-Earth Doped Sol-Gel Derived Nano-Glass Ceramics.

Rare-earth doped oxyfluoride glass ceramics represent a new generation of tailorable optical materials with high potential for optical-related applications such as optical amplifiers, optical waveguides, and white LEDs. Their key features are related to the high transparency and remarkable luminescence properties, while keeping the thermal and chemical advantages of oxide glasses. Sol-gel chemistry offers a flexible synthesis approach with several advantages, such as lower processing temperature, the ability to control the purity and homogeneity of the final materials on a molecular level, and the large compositional flexibility. The review will be focused on optical properties of sol-gel derived nano-glass ceramics related to the RE-doped luminescent nanocrystals (fluorides, chlorides, oxychlorides, etc.) such as photoluminescence, up-conversion luminescence, thermoluminescence and how these properties are influenced by their specific processing, mostly focusing on the findings from our group and similar ones in the literature, along with a discussion of perspectives, potential challenges, and future development directions.

2,7-Carbazole Derived Organoboron Compounds: Synthesis and Molecular Fluorescence.

Triarylboranes have drawn much attention in OLEDs owing to their remarkable solid-state luminescence properties. Here two new A-D-A type compounds, 2,7-bis(dimesitylboryl)-N-ethyl-carbazole (BCz) using triarylborane as electron acceptor and carbazole as electron donor while 2,7-bis((4-(dimesitylboryl)phenyl)ethynyl)-9-ethyl-carbazole (BPACz) using phenylacetylene as extra conjugated bridge, have been synthesized and their photoluminescence related properties in various states have been investigated both experimentally and theoretically. Both compounds show blue emission with high quantum yields, being potential candidates for blue OLED materials.

Cover Feature: Mechanochromic Luminescence (MCL) of Purely Organic Two‐Component Dyes: Wide‐Range MCL over 300 nm and Two‐Step MCL by Charge‐Transfer Complexation (Chem. Eur. J. 56/2021)

The creation of two-component dyes has proven to be an effective strategy to achieve remarkable mechanochromic luminescence (MCL) properties. The shift of the maximum emission wavelength (Δλem) range of a bis(1-pyrenylmethyl)diamine derivative has been significantly improved by mixing it with typical organic dyes that do not exhibit MCL behavior. Most notably, a wide-range MCL (Δλem=340 nm) has been achieved for a mixture with 3,4,9,10-perylenetetracarboxylic diimide. Furthermore, a two-step MCL has been realized by mixing with 9,10-anthraquinone. More information can be found in the Full Paper by S. Ito, T. Tachikawa, et al. (DOI: 10.1002/chem.202102700).

Eu3+-β-diketone functionalized covalent organic framework hybrid material as a sensitive and rapid response fluorescent sensor for glutaraldehyde

A covalent organic framework (named as TpDq) linked by β-ketoamine was prepared by imine condensation reaction with 1,3,5-triformylphloroglucinol (TFP) and 2,6-diaminoanthraquinone (DAAQ) as building blocks. Via employing a functionalized modification strategy, a new lanthanide complex Eu3+-β-diketone functionalized covalent organic framework hybrid material, Eu-TTA@TpDq (TTA = 2-thenoyltrifluoroacetone), has been synthesized. After post-synthetic modification (PSM), the shape and structure of the parent framework is well preserved and the modified material shows remarkable luminescence properties. Based on this, we designed it as a fluorescent probe and tried to use it to sense common aldehydes. The results indicate that Eu-TTA@TpDq exhibits a turn-off response toward glutaraldehyde which can distinguish from other common aldehydes. The fluorescent probe has the advantages of reusability, pH stability (4.50–8.52), fast luminescence response (<1 min) and low detection limit. The linear range of this method was 0–100 μM; the detection limit was 4.55 μM; the relative standard deviation was 2.16%. Furthermore, it has broad application prospect in both practical sensing of glutaraldehyde in water environment and simple detection of glutaraldehyde vapor. In addition, we preliminarily discussed the possible sensing mechanism.

Temperature sensitive properties and preparation of europium complexes with double ligands

Temperature sensitive paints (TSPs) are a class of rising materials for non-contact temperature measurement technology. Efficient complexes with remarkable luminescent properties play the core role in TSPs. Rare earth organic complexes are often used as probe molecules for TSPs because of their long fluorescence lifetime, narrow fluorescence emission peaks, high fluorescence intensity, and large Stokes shift. Herein, two europium-based complexes, Eu(PCCA)3 phen and Eu (PMCA)3 phen, were synthesized under hydrothermal conditions, using europium(III) oxide (Eu2 O3 ), p-chlorocinnamic acid (PCCA), p-methoxy cinnamic acid (PMCA) and 1,10-phenanthroline (phen) as raw materials. Two temperature sensitive paints (Eu(PCCA)3 phen/PMMA and Eu(PMCA)3 phen/PMMA) were obtained by the polymerization of methyl methacrylate (MMA) with different europium complexes. The structure, morphology, luminescent properties of the europium complexes and temperature quenching properties of the TSPs were characterized by infrared (IR) spectroscopy, scanning electron microscopy (SEM), and fluorescence spectroscopy. The fluorescence results show that both of the two TSPs have good temperature quenching performance in the range 20-100°C with high sensitivity 50-60°C and 80-90°C, respectively. Furthermore, the highest sensitivity of Eu(PCCA)3 phen/PMMA is greater than that of Eu(PMCA)3 phen/PMMA. This work can provide a universal way for preparing efficient TSPs in practical applications.

A novel narrow band blue-emitting phosphor Rb2ZrSi3O9: Eu2+ with low thermal quenching and high quantum efficiency

Developing phosphors with narrow band emission and excellent performance is the main goal of current leading research. In this study, a novel narrow band blue-emitting phosphor Rb2ZrSi3O9: Eu2+ was prepared that can be fully excited by near ultraviolet (NUV) light, emits a bright blue light peak at 470 nm, and has a full width at half maximum (FWHM) of 60 nm. The synthesized Rb2ZrSi3O9: Eu2+ had excellent photoluminescence properties that were reflected in its good thermal stability (up to 82%) and high internal quantum efficiency (up to 75%). These remarkable luminescence properties were mainly ascribed to the highly symmetric and dense crystal structure composed of [Si3O9]6- ring pairs. Multiple emission centers in the Rb2ZrSi3O9: Eu2+ phosphor were confirmed through the photoluminescence (PL) spectra and time-resolved (PL) spectra. A bright warm WLED device with a low correlated color temperature (3386 K) and high color-rendering index (CRI~89.3) was produced by combining the blue phosphor with (Sr, Ba)2SiO4: Eu2+ and CaAlSiN3: Eu2+ and NUV (380 nm). The results indicate that Rb2ZrSi3O9: Eu2+ could be a promising phosphor for use in WLEDs.

Lead confinement and fluorimetric detection using zeolites: towards a rapid and cost-effective detection of lead in water

Metal clusters stabilized in zeolites have emerged as promising candidates for optoelectronic applications due to their remarkable luminescent properties. These optical properties have been exploited to develop fast and highly sensitive methods for optical sensing in environmental monitoring. However, to date, these materials have not been proposed as a detection method based on their luminescent response for sensing toxic metal ions. In this report, we synthesized luminescent lead (Pb) clusters into the cavities of synthetic F9-NaX zeolites, which were used as scaffolds to confine and detect Pb2+ ions in water through a fluorimetric mode. These Pb-F9 samples display an intense cyan emission in dehydrated form. Also, a correlation between the luminescence intensity of the materials and the lead loadings was observed, obtaining a low limit of detection of 1.248 ppb and a limit of quantification of 3.782 ppb. The results clearly demonstrate the potential of luminescent lead-exchanged F9 zeolites as one-step method for lead monitoring in water using a rapid and low-cost strategy.

Aptamer-functionalized lipid-core micelles loaded with rhenium tricarbonyl complex

Due to its distinctive physicochemical properties, diimine rhenium(I) tricarbonyl complexes are one of the most common type of complexes used in cellular imaging. The reasonably simple synthesis and modification of rhenium complexes in addition to their stability and remarkable luminescent properties provide a robust method to perform this goal. In general, organometallic complexes must be biocompatible to development imaging agents. Consequently, modification and bio-functionalization of the transition complexes is crucial to enhance biocompatibility. Here, we synthesize and characterize the luminescent tricarbonyl rhenium complex, [(bpy)(H2O)Re(CO)3]+, and propose a reasonably simple preparation of an aptamer-functionalized lipid core micelle (LCM), loaded with this complex, to endow it with suitable properties to be used in cellular imaging. The [(bpy)(H2O)Re(CO)3]+ exhibit a broad emission band centered around 550 nm at room temperature after excitation at 360 nm. The luminescent intensity is higher in nonpolar solvents such as chloroform. The complex was loaded into LCMs and, at the same time, the carrier was functionalized in situ with the nucleolin aptamer, AS1411, to improve the complex delivery and uptake to target cells. After physicochemical and spectroscopic characterization of the aptamer-functionalized vehicle, cellular studies were performed to evaluate its toxicity and its efficiency as cellular imaging agent. The combined AS1411 aptamer-functionalized lipid core micelle system effectively encapsulated the [(bpy)(H2O)Re(CO)3]+ complex, maintained its luminescent properties, and showed potential features to be used in cellular imaging experiments.

Aptamer-Functionalized Lipid-Core Micelles Loaded with Rhenium Tricarbonyl Complex

Due to its distinctive physicochemical properties, diimine rhenium(I) tricarbonyl complexes are one of the most common type of complexes used in cellular imaging. The reasonably simple synthesis and modification of rhenium complexes in addition to their stability and remarkable luminescent properties provide a robust method to perform this goal. In general, organometallic complexes must be biocompatible to development imaging agents. Consequently, modification and bio-functionalization of the transition complexes is crucial to enhance biocompatibility. Here, we synthesize and characterize the luminescent tricarbonyl rhenium complex, [(bpy)(H 2 O)Re(CO) 3 ] + , and propose a reasonably simple preparation of an aptamer-functionalized lipid core micelle (LCM), loaded with this complex, to endow it with suitable properties to be used in cellular imaging. The [(bpy)(H 2 O)Re(CO) 3 ] + exhibit a broad emission band centered around 550 nm at room temperature after excitation at 360 nm. The luminescent intensity is higher in nonpolar solvents such as chloroform. The complex was loaded into LCMs and, at the same time, the carrier was functionalized in situ with the nucleolin aptamer, AS1411, to improve the complex delivery and uptake to target cells. After physicochemical and spectroscopic characterization of the aptamer-functionalized vehicle, cellular studies were performed to evaluate its toxicity and its efficiency as cellular imaging agent. The combined AS1411 aptamer-functionalized lipid core micelle system effectively encapsulated the [(bpy)(H 2 O)Re(CO) 3 ] + complex, maintained its luminescent properties, and showed potential features to be used in cellular imaging experiments.

Preparation of microporous MoS2@carbon nanospheres for the electrochemical detection of hydrogen peroxide

Molybdenum sulfide (MoS2) may be a promising material for biosensing applications due to their remarkable electronic, electrochemical attributes, and luminescence properties. Herein, thin layered MoS2 deposited on carbon nanospheres with microporosity (m-MoS2@CNS) was prepared through a simple dip-calcination method. The as-prepared m-MoS2@CNS exhibits the well-defined pore, high surface area, and good electrical conductivity, which lead to facilitated electron/ion transport during electrochemical reaction. Based on their outstanding electrochemical properties, the m-MoS2@CNS reveals the excellent performance as a non-enzymatic detection of hydrogen peroxide in a wide concentration range, from 0.1 mM to 20 mM, with high sensitivity (8.89 μA/mM·cm2) and low limit of detection (7.5 μM, S/N = 3). Moreover, the electrode has a favorable selectivity, reproducibility, and fast response time (~ 7 s). Thus, the m-MoS2@CNS has a great potential as an electrocatalyst for the efficient detection of hydrogen peroxide.

Nano-Micro Dimensional Structures of Fiber-Shaped Luminous Halide Perovskite Composites for Photonic and Optoelectronic Applications.

Perovskite nanomaterials have been revealed as highly luminescent structures regarding their dimensional confinement. In particular, their promising potential lies behind remarkable luminescent properties, including color tunability, high photoluminescence quantum yield, and the narrow emission band of halide perovskite (HP) nanostructures for optoelectronic and photonic applications such as lightning and displaying operations. However, HP nanomaterials possess such drawbacks, including oxygen, moisture, temperature, or UV lights, which limit their practical applications. Recently, HP-containing polymer composite fibers have gained much attention owing to the spatial distribution and alignment of HPs with high mechanical strength and ambient stability in addition to their remarkable optical properties comparable to that of nanocrystals. In this review, the fabrication methods for preparing nano-microdimensional HP composite fiber structures are described. Various advantages of the luminescent composite nanofibers are also described, followed by their applications for photonic and optoelectronic devices including sensors, polarizers, waveguides, lasers, light-down converters, light-emitting diode operations, etc. Finally, future directions and remaining challenges of HP-based nanofibers are presented.

Tunable white emission of silver-sulfur-zeolites as single-phase LED phosphors

Metal clusters confined inside zeolite materials display remarkable luminescent properties, making them very suitable as potential alternative phosphors in white LED applications. However, up to date, only single-color emitters have been reported for luminescent metal-exchanged zeolites. In this study, we synthesized and characterized white emitting silver-sulfur zeolites, which show a remarkable color tunability upon the incorporation of silver species in highly luminescent sulfur-zeolites. Via a combined steady-state and time-resolved photoluminescence spectroscopy characterization, we suggest that the observed luminescence and tunability arise from the presence of two different species. The first associated to an orange-red emitting silver cluster (Ag-CL), whereas the second is related to a blue-white emitting S-Ag-species. The relative contribution of both luminescent species depends on the synthesis procedure. It was shown that the formation of the blue-white emitting S-Ag-species is favored upon a heat-treatment of the samples.