Remarkable Luminescence Properties Research Articles

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.

Comparative life cycle assessment of bottom-up synthesis routes for carbon dots derived from citric acid and urea

Carbon dots (CDs) are carbon-based nanoparticles with remarkable luminescent properties, which have made them exciting and suitable alternatives to more traditional fluorophores and even to more recent luminescent nanomaterials (such as metal-based quantum dots). However, despite this high interest on CDs, there has been no focus on their sustainable development and fabrication, and so, there is lacking concrete data on their environmental impacts. A life cycle assessment (LCA) approach was used here to compare and understand the environmental impacts of carbon dots (CDs) obtained via six representative bottom-up synthetic strategies (cradle-to-gate). These routes consist on hydrothermal and microwave-assisted synthesis of CDs derived of citric acid (with the occasional addition of urea), which represent current trends in the synthesis of CDs. Results show that for hydrothermal synthesis the use of electricity is dominant for almost all environmental categories, while citric acid produces most impacts for microwave-assisted synthesis. A performance-based comparison was also made by rescaling results with the fluorescence quantum yield of the CDs. This approach changed the rank order of preference in all categories by a significant margin. While previous analysis indicated microwave-assisted synthesis of citric acid-derived CDs to be the most benign in environmental terms, now the option is the synthesis (either by hydrothermal or microwave-assisted treatment) of urea and citric acid-derived CDs.

Anaerobic reduction of europium by a Clostridium strain as a strategy for rare earth biorecovery

The biorecovery of europium (Eu) from primary (mineral deposits) and secondary (mining wastes) resources is of interest due to its remarkable luminescence properties, important for modern technological applications. In this study, we explored the tolerance levels, reduction and intracellular bioaccumulation of Eu by a site-specific bacterium, Clostridium sp. 2611 isolated from Phalaborwa carbonatite complex. Clostridium sp. 2611 was able to grow in minimal medium containing 0.5 mM Eu3+. SEM-EDX analysis confirmed an association between Eu precipitates and the bacterium, while TEM-EDX analysis indicated intracellular accumulation of Eu. According to the HR-XPS analysis, the bacterium was able to reduce Eu3+ to Eu2+ under growth and non-growth conditions. Preliminary protein characterization seems to indicate that a cytoplasmic pyruvate oxidoreductase is responsible for Eu bioreduction. These findings suggest the bioreduction of Eu3+ by Clostridium sp. as a resistance mechanism, can be exploited for the biorecovery of this metal.

Structural and Luminescence Properties of Anthracene- and Biphenyl-Based Lanthanide Bisphosphonate Ester Coordination Polymers.

Coordinative networks containing lanthanide ions attached via phosphonate ester functionalities provide remarkable luminescence properties. On the basis of ditopic phosphonic ester ligands with biphenylene and 9,10-anthracenylene bridges, a series of compounds with formal composition {[M(NO3)3]L} n or {[M(NO3)3]2(L1)3} n (L = C28H40O6P2; L1 = C26H40O6P2) with M = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y have been synthesized, structurally characterized, and the luminescence behavior was explored in the visible and NIR spectral regions, where applicable. In contrast to closely related networks based on biphenyl bisphosphonate esters from previous work, no evidence for ligand-to-metal energy transfer could be observed, despite strong near-infrared emission in some cases. Unique behavior is found for the Eu derivative with the 9,10-anthracenylene bridge, which is nonemissive, showing neither ligand- nor metal-based emission.

Origin of the bright photoluminescence of few-atom silver clusters confined in LTA zeolites.

Silver (Ag) clusters confined in matrices possess remarkable luminescence properties, but little is known about their structural and electronic properties. We characterized the bright green luminescence of Ag clusters confined in partially exchanged Ag-Linde Type A (LTA) zeolites by means of a combination of x-ray excited optical luminescence-extended x-ray absorption fine structure, time-dependent-density functional theory calculations, and time-resolved spectroscopy. A mixture of tetrahedral Ag4(H2O) x2+ (x = 2 and x = 4) clusters occupies the center of a fraction of the sodalite cages. Their optical properties originate from a confined two-electron superatom quantum system with hybridized Ag and water O orbitals delocalized over the cluster. Upon excitation, one electron of the s-type highest occupied molecular orbital is promoted to the p-type lowest unoccupied molecular orbitals and relaxes through enhanced intersystem crossing into long-lived triplet states.

Synthesis, Structures and Recognition Properties of Two Cadmium(II) Phosphonates for Highly Selective Sensing of Cr2O72− and CrO42− Anions

AbstractTwo cadmium (II) phosphonates, [Cd(MPBP)(2, 2′−bipy)(H2O)]⋅H2O (1) and [Cd(H2BPDP)(2,2′−bipy)2(H2O)]⋅H2O (2) [H2MPBP=4,4−Bis(monoethylphosphonomethyl)biphenyl, H4BPDP=biphenyl−4,4′−diylbis(methylene)diphosphonic acid, 2,2′−bipy=2,2′−bipyridine], had been successfully synthesized under hydrothermal conditions with different reaction temperatures by using H2MPBP as the phosphonate ligand and 2,2′−bipyridine as the second organic ligand. The compound 1 exhibited a 3D supramolecular structure, in which {CdN2O4} polyhedra and {CPO3} tetrahedra were interconnected by MPBP anions to form a 1D double chain via corner–sharing. Neighboring chains were linked into a 2D supramolecular sheet in the ac–plane by hydrogen bonding interactions, which were further assembled through π−π stacking interactions to form a 3D supramolecular structure. Compound 2 was assembled through π−π stacking and hydrogen bonding interactions to form a 1D supramolecular structure. Furthermore, both compounds exhibited remarkable luminescent properties, and could be applied as the high selective and sensitive luminescent sensors in the sensing of Cr2O72− and CrO42− anions through the luminescence quenching effect with a low–detection limit of 3.5 × 10−7 M and 4.6 × 10−7 M (for 1) and 6.1 × 10−7 M and 4.3 × 10−7 M (for 2), respectively. Additionally, the probable mechanisms for the quenching behaviour for the two compounds had also been investigated in detail.

A highly sensitive luminescent metal–organic framework thermometer for physiological temperature sensing

Thermal sensing and imaging in the physiological temperature range are of great importance for studying physiological processes and treating diseases. Metal–organic frameworks (MOFs) exhibit great promise for developing luminescent thermometers due to their remarkable structural diversities and tunable luminescence properties. Here, we synthesized a series of luminescent mixed-lanthanide MOFs, EuxTb1-xBPT (x = 0.019, 0.058, 0.106; H3BPT = biphenyl-3,4′,5-tricarboxylate acid) and adopted powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) to characterize the resulting products. The temperature-dependent photoluminescence emission spectra were recorded to investigate their potential applications in physiological temperature readout. It is found that the intensity ratio of Tb3+ to Eu3+ is linearly correlated with temperature and the relative sensitivity is higher than 1.5%/°C over the entire physiological temperature range. Furthermore, the temperature-dependent luminescence color emission allows for visual colorimetric temperature measurements. Luminescence lifetime testing and triplet energy level measurement were further conducted to study the mechanism.

Photo-Induced Assembly of a Luminescent Tetraruthenium Square.

Self-assembly is a powerful synthetic tool that has led to the development of one-, two- and three-dimensional architectures. From MOFs to molecular flasks, self-assembled materials have proven to be of great interest to the scientific community. Here we describe a strategy for the construction and de-construction of a supramolecular structure through unprecedented photo-induced assembly and dis-assembly. The combination of two approaches, a [n×1]-directional bonding strategy and a ligand photo-dissociation strategy, allows the photo-induced assembly of a polypyridyl RuII precursor into a discrete molecular square. Diffusion-ordered NMR spectroscopy confirmed the synthesis of a higher volume species, while the identity of the species was established by high-resolution mass spectrometry and single-crystal X-ray diffraction studies. The self-assembled square is not obtained by classical thermal techniques in similar conditions, but is obtained only by light-irradiation. The tetraruthenium square has an excited-state lifetime (135 ns), 40 times that of its mononuclear precursor and its luminescence quantum yield (1.0 %) is three orders of magnitude higher. These remarkable luminescence properties are closely related to the relatively rigid square structure of the tetraruthenium assembly, as suggested by slow radiationless decay and transient absorption spectroscopy. The results described herein are a rare example of photo-induced assembly and dis-assembly processes, and can open the way to a new avenue in supramolecular chemistry, leading to the preparation of structurally organized supermolecules by photochemical techniques.

Simple and Versatile Preparation of Luminescent Amphiphilic Platinum(II)-containing Polystyrene Complexes With Transformable Nanostructures Assisted by Pt⋅⋅⋅Pt and π-π Interactions.

Platinum(II)-containing polystyrene (PS) complexes have been synthesized by dehydrohalogenation of α-alkyne-PS and chloroplatinum(II) precursors with different functionalities on the terpyridine ligands. Through modulation of the hydrophilicity/hydrophobicity of the terpyridine ligands and hence the overall amphiphilicity of the complexes, the complexes can undergo self-assembly into various superstructures with remarkable luminescence properties in different solution mixtures, as revealed by electron microscopy, UV/Vis absorption and emission spectroscopy. Pt⋅⋅⋅Pt and/or π-π interactions among the platinum(II) terpyridine moieties are found to play substantial roles in the stabilization of the superstructures and the turn-on/off of the triplet metal-metal-to-ligand charge transfer (3 MMLCT) emission of the complexes.

Preparation and optical properties of a novel double-perovskite phosphor, Ba2GdNbO6:Mn4+, for light-emitting diodes

Red phosphors serve an important function as red components of warm white light-emitting diodes (WLEDs). Given their remarkable luminescent properties and low cost, Mn4+-doped phosphors are attracting significant attention. In this study, the novel red phosphor Ba2GdNbO6:Mn4+ was synthesized through high-temperature solid-state reaction. The host Ba2GdNbO6 with a double-perovskite structure was investigated. Scanning electron microscopy and thermogravimetric analysis were performed to evaluate the structure and thermal stability of the phosphor, respectively. PLE and photoluminescence spectra were further used to study the luminescence properties of the phosphor. Moreover, crystal field strength and Racah parameters were calculated to estimate the nephelauxetic effect of Mn4+ on the Ba2GdNbO6 host lattice. Thermal quenching characteristics were also analyzed. The fabricated red-emitting LED revealed its potential application in WLEDs.

A Highly Stable 3D Luminescent Indium-Polycarboxylic Framework for the Turn-off Detection of UO22+, Ru3+, and Biomolecule Thiamines.

Hydrothermal reaction of the multidentate organic ligand (H6TTHA) with indium chloride (InCl3) produced a highly stable 3D luminescent indium-organic framework [In2(OH)2(H2TTHA)(H2O)2]n (1). Complex 1 exhibits remarkable luminescent properties, especially the multifunction sensitivity and selectivity for detecting Ru3+, UO22+; as well as small biomolecules thiamines (TPP, TMP, and TCl) based on a "turn-off" manner. In particular, the pyrophosphate groups of TPP and the phosphate groups of TMP could further affect the quenching rate, leading to different luminescent responds. In addition, we also discussed and proved the luminescence quenching mechanism in detail through comparative test and PXRD characterization. Therefore, complex 1 could be used as a kind of excellent luminescence sensor to detect Ru3+, UO22+, and thiamines (TPP, TMP, and TCl).

Controllable synthesis of Sc2Mo3O12microcrystals with exposed {001} facets and their remarkable tunable luminescence properties by doping lanthanides

Novel chocolate-like scandium molybdate precursors with exposed {001} facets were hydrothermally synthesized in the presence of PVP, which were transformed into morphology-preserved Sc2Mo3O12 crystals by calcination at 800 °C for 2 h. The as-synthesized samples were characterized by XRD, FT-IR SEM, TEM, HRTEM, and PL analysis. Four different types of precursors including prismatic structures, octahedra, truncated octahedra and compressed decahedra could be obtained by varying the amount of MoO42−. Moreover, in the presence of H+, the percentage of high-energy {001} facets could be enhanced. The Mo sources, PVP consumption, reaction time and hydrothermal temperature had significant influences on the morphology of the precursors. As good matrix materials, the tunable down/upconversion (DC/UC) luminescence properties of Sc2Mo3O12:Ln3+ (Ln = Tb, Eu, Tb/Eu, Yb/Er, Yb/Ho, Yb/Tm) were comprehensively investigated. It is found that the materials showed strong morphology-dependent luminescence properties. Particularly, the energy transfer (ET) of MoO42− → Tb3+ → Eu3+ resulted in multicolor emissions from green to red in Sc2Mo3O12:5%Tb3+,x%Eu3+. The Sc2Mo3O12:Ln3+ (Ln = Tb, Eu, Tb/Eu, Yb/Er, Yb/Ho, Yb/Tm) microcrystals show great potential applications in the areas of fluorescent lamps and color displays.

Divalent Tetra- and Penta-phenylcyclopentadienyl Europium and Samarium Sandwich and Half-Sandwich Complexes: Synthesis, Characterization, and Remarkable Luminescence Properties

The synthesis of the bulky divalent (polyphenylcyclopentadienyl)lanthanoid sandwich complexes [Ln(C5Ph5)2] (Ln = Sm, Eu) and [Ln(C5Ph4H)2(solv)] (Ln = Sm, solv = thf; Ln = Eu, solv = dme)], from redox-transmetalation/protolysis (RTP) reactions, has been achieved. An analogous reaction with Yb afforded the solvent-separated ion pair [Yb(dme)4][C5Ph4H]2. In addition, rare divalent samarium halide complexes [Sm(C5Ph5)(μ-Br)(thf)2]2 and [Sm(C5Ph4H)I(thf)3], were also prepared, either by RTP or ligand rearrangement. X-ray studies showed that the [Ln(C5Ph5)2] complexes adopt highly symmetrical sandwich structures, whereas the [Ln(C5Ph4H)2(solv)] complexes have open sandwich structures. The unexpected, but limited, solubility of the [Ln(C5Ph5)2] complexes allowed for variable-temperature NMR spectra of [Sm(C5Ph5)2] to be obtained. Detailed 1D and 2D NMR studies were conducted on [Sm(C5Ph4H)2(thf)] to ascertain its structure in donor and nondonor solvents. During the course of these studies, the mixed tetraarylcy...

Targeting Wnt Canonical Signaling by Recombinant sFRP1 Bound Luminescent Au-Nanocluster Embedded Nanoparticles in Cancer Theranostics.

Secreted frizzled-related protein 1 (SFRP1) is a natural blocker of the Wnt signaling pathway in normal adult cells but is epigenetically silenced in cancer cells leading to aberrant proliferation. In this study, we have reported novel composite nanoparticles fabricated with gold nanocluster embedded chitosan and alginate, bound to bacterially expressed human recombinant sFRP1. The Wnt pathway, which is upregulated in cancer, has been specifically targeted with the nanoparticles to achieve an antiproliferative effect on cancer cells, as evident from reduced levels of downstream molecules, namely, β-catenin, cyclin D1, and survivin. The nanoparticles enabled sustained release of sFRP1 outside the cells, where it is functional. Moreover, remarkable luminescence properties of gold nanoclusters were exploited for binding, imaging, and tracking studies. Co-therapy of sFRP1-loaded nanoparticles with the drug cisplatin targeted two independent pathways to induce apoptosis, as documented by flow cytometry based assays. Overall, this nanosystem is promising for tracking, imaging, and targeting cancer signaling with therapeutic protein.

ChemInform Abstract: Metal—Organic Frameworks for Luminescence Thermometry

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